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Abstract(30) HTML(8) PDF 1574KB(5)
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Pyrolysis char was prepared from high sulfur and iron content textile dyeing sludge. The combined states of S and Fe in the samples before and after pyrolysis and the removal characteristics of Hg0 by pyrolysis char were studied. The performance of Hg0 removal was improved by air oxidation and ZnCl2 impregnation. The results showed that S in sludge was divided into sulfate, sulfide, and organic sulfur. Fe existed as Fe3+ and Fe2+ compounds. After pyrolysis, inorganic sulfur was transferred to organic sulfur and Fe3+ was transferred to Fe2+. Most S and Fe were retained in pyrolysis char and some formed pyrrhotite (Fe1−xS). The specific surface area of raw char was small and had a certain Hg0 removal capacity, dominated by chemical adsorption. When the air oxidation time was controlled within 12 h, the Hg0 adsorption capacity of pyrolysis char at high temperature (≥600 ℃) was increased by more than 46%. During pyrolysis of ZnCl2 impregnated sludge, more S was fixed in pyrolysis char to generate ZnS. The Hg0 adsorption capacity of ZnCl2 modified char pyrolyzed at 600 ℃ reached 28.71 μg/g in 30 min. With air oxidation, the Hg0 removal efficiency was further improved. After oxidation for 12 h, the Hg0 adsorption capacity was 43.75 μg/g.
Abstract(12) HTML(6) PDF 1659KB(3)
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Aromatics, as the important industrial basic chemicals, can be prepared by direct or indirect conversion of syngas. Co Mpared with the indirect conversion method, the direct syngas to aromatics route (STA) has the advantages of high feedstock conversion, short process, and easy product separation. In this paper, we mainly introduce the progress of research on the direct syngas to aromatics by Fischer-Tropsch route, and focus on the effects of the metal oxide coupled molecular sieve bifunctional catalysts on the catalytic reaction performance, such as the selection of Fischer-Tropsch active components and additives, molecular sieve acidity modulation and pore structure regulation; Then we summarize the influence of reaction temperature, pressure, air velocity, hydrogen to carbon ratio and other parameters on the reaction performance. At last, based on the mechanisms of STA reaction and catalyst deactivation, the method for improving the activity and stability of STA catalysts is discussed.
Abstract(36) HTML(13) PDF 33324KB(3)
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The catalytic conversion of syngas to value-added hydrocarbons is an important path for the clean utilization of biomass or coal sources. Zeolites as supports or solid acidity catalysts are commonly used for the C–C formation/cleavage in syngas conversion, owing to their unique microporous structure, accurately tunable active sites and high hydrothermal stability. The research progress of direct conversion of syngas to hydrocarbon using metal loaded zeolites, bifunctional oxide-zeolite (OX-ZEO) catalysts, and core-shell structured catalysts was reviewed. The effects of zeolite structure and acidity on the reaction pathway and mechanism as well as the product distribution are highlighted. An outlook was given on the perspective of zeolite catalysis in syngas conversion.
Abstract(40) HTML(7) PDF 6552KB(6)
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The light olefins, mainly ethylene, propylene and butene, are basic building blocks in chemical industry. The direct conversion of syngas to lower olefins considered as a new significant and attractive process for producing lower olefins from non-petroleum resources, owing to its process simplicity and low energy consumption. The light olefins can be directly produced from syngas via two routes, namely, the Fischer-Tropsch to olefins (FTO) reaction and oxide-zeolite (OX-ZEO) bifunctional catalysis strategy (SDTO). This paper mainly reviews recent developments of SDTO, with emphasis on the effects of catalyst design, catalyst preparation and interphase renovation on reactivity. The targeting control of operating parameters such as H2/CO ratio, temperature, pressure and contact for higher production of light olefins has also been clarified. Applications of new in situ, in real-time techniques to identify the structure-function relationship and the reaction mechanism are summarized. The recent progress including the applications of new in situ, real-time techniques to identify the structure-function relationship and the reaction mechanism are reviewed in detail. With this, the authors put forward insights into significant promising tendencies and confronting challenges in the strategy of OX-ZEO.
Abstract(21) HTML(10) PDF 11564KB(7)
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Tar deposition is one of the obstructions which limits the large -scale use of biomass gasification. Catalytic reforming is the most available and efficient technology for which the investigation of a high and stable catalyst is of great significance. Great attention has been paid to the char supported metal catalysts for their simple preparation, low cost and easy recovery of active metals. In this work, based on the origin and preparation of char-supported metal catalysts, we firstly reviewed its performance for the steam reforming of tar model compound, especially for the high activity and stability of highly-dispersed metal under low temperature. Additionally, we also reviewed biomass tar reforming over the char supported metal catalyst, compared their performance with traditionally tar reforming catalysts, and summarized the relevant catalytic reaction mechanism. It can be concluded that the catalysts have good application advantages and prospects. At first, char supports are favor to disperse active metal sites, thus the prepared nano catalysts are active for tar reforming into H2-rich syngas at mild conditions. Furthermore, energy and metal oxides can be obtained by burning spent catalysts. However, more researches are necessary to deeply reveal the mechanism for tar reforming and improve the stability of char supported metal catalysts.
Abstract(6) HTML(5) PDF 4161KB(0)
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Because there were much more oxygen-containing functional groups for low-rank coal, a large amount of CO and CO2 were produced during the pyrolysis process. Catalytic hydrogenation of CO or CO2 to light aromatics could be realized by supplying active hydrogen from methanol. Density functional theory (DFT) was used to investigate the mechanism of CO hydrogenation to aromatics via olefins intermediates over Fe/HZSM-5 catalyst under methanol atmosphere. The results showed that light olefins were formed by CO hydrogenation on Fe5C2 (510) surface. C−C bond coupling and chain propagation were achieved through multiple processes such as methylation and deprotonation. Methylation required a high activation energy among these processes. The aromatization of ${\rm{C}}^+_6$ to benzene was carried out by reactions of hydrogen transfer, deprotonation and cyclization. Hydrogen transfer was the most difficult to happen. In the whole process of CO hydrogenation to aromatics, the energy barrier of methylation was the highest, which was the rate-determining step.
Abstract(26) HTML(8) PDF 5853KB(7)
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One-step synthesis of light olefin and liquid fuel using syngas as platform compound is an important way to effectively utilize carbon resources. It has the characteristics of short process, low energy consumption, and is of good industrial application prospects. The one-step direct conversion of syngas to prepare light olefins and liquid fuels consists of two process routes: the Fischer-Tropsch (F-T) route and the bifunctional catalytic route. In this paper, the reaction mechanisms of both routes are briefly described. The optimal design of Fe-based and Co-based catalysts by inert supports, the effect of F-T metal particle size, reaction conditions, and catalyst structure on the catalytic performance and reaction process have been elaborated. In the bifunctional catalytic route, the influences of the CO activation components, zeolite type, the proportion and particle size of the metal oxide elements, the acidity and pore size of zeolites and the methods for coupling the CO activation components and zeolite on the performance of the catalysts were analyzed in detail. The advantages and challenges of the two routes are summarized. The development trends of efficient catalysts in the future have also been prospected.
Abstract(13) HTML(8) PDF 954KB(5)
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Carbon dioxide capture and utilization (CCU) is the best way to solve the problem of reducing concentration of carbon dioxide in the atmosphere, and it has a good prospect for development. On this basis, chemical researchers have explored the methods of synthesizing valuable organic compounds with CO2 as carbon source. The oxazolidinones are commonly used to synthesize drugs, and they are significant in organic synthesis as chiral molecules and intermediates. The synthetic methods of oxazolidinones have emerged in recent years. Furthermore, the methods of using carbon dioxide as a carbon source have attracted many researchers. In earlier years, people explored cycloaddition reactions of carbon dioxide and aziridines to synthesize oxazolidinones, and they took alkali metals, Cr, Al or other metals as catalysts to improve the efficiency of the reactions. Because of the cost and the principle of green synthesis, it is more suitable for large-scale reaction to select cheap and easily available ionic liquids or no catalysts. In addition, carbon dioxide and compounds such as β-amino alcohols, unsaturated amines and 1, 2-dihalohydrogenated compounds can obtain moderate or even excellent yields under different reaction conditions. In this paper, we summarized the synthetic methods of oxazolidinones using CO2 with different raw materials in recent years.
Abstract(6) HTML(8) PDF 14532KB(0)
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In this paper, ordered mesoporous HZSM-5 zeolite with different particle sizes (20, 30 and 40 nm) and the Si/Al ratio of 40 was successfully prepared by the hydrothermal methods. The structure, morphology and surface acidity of the synthesized samples were characterized by XRD, SEM, TEM, N2 isothermal adsorption/desorption and Py-IR, and their catalytic activities were tested in the methanol to aromatics process on a fixed-bed reactor. The experimental results showed that the catalytic performance of ordered mesoporous HZSM-5 zeolite with different particle sizes was different for the methanol to aromatics reaction. The ordered mesoporous HZSM-5 zeolite of 20 nm exhibited excellent catalytic performance with the selectivity of light aromatics up to 60% and no significant deactivation of the catalyst after 51 h of continuous operation.
Abstract(6) HTML(1) PDF 6536KB(1)
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Long-chain linear α-olefins (LAOs) are important industrial chemicals, which are mainly obtained from petrochemical process. As influence of the global temperature rise aggravates, research on CO2 control and valorization has been receiving attention. Fischer-Tropsch synthesis (FTS) reaction produces a certain proportion of LAOs, providing an alternative technical route to obtain LAOs. In this paper, research progress of iron-based catalysts, including the roles of promoters and supports was analyzed for the process of CO2 hydrogenation to LAOs. Key factors affecting the selectivity of LAOs were expounded. Challenges and possible solutions of the reaction were summarized, and an outlook for designing high-efficient iron-based catalysts was presented.
Abstract(1) HTML(0) PDF 3227KB(0)
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The direct coal hydrogenation is a clean and efficient utilization of low rank coal for preparing high quality liquid fuels and chemicals. The isotope tracer technology has been widely used in the mechanism of direct coal hydrogenation. The isotope tracer technology is briefly introduced and the progress of its application in the reaction mechanism of coal hydrogenation liquefaction, coal hydropyrolysis and other direct coal hydrogenation is reviewed in this paper.
Abstract(87) HTML(50) PDF 3123KB(15)
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The Cu/Zn/Al precursor by coprecipitation was treated with formic acid and then calcined in N2 to obtain Cu-ZnO-Al2O3 catalyst (CZA) for the CO2 hydrogenation to methanol. XRD, BET, TG-DSC, SEM, H2-TPR, N2O titration, XPS-AES and CO2-TPD characterization techniques were used to analyze the phase composition, structural properties of the catalyst, and the Cu specific surface area, the dispersion and valence of the Cu species. The results showed that the formic acid treatment tuned the ratio of Cu+ and Cu0, increased the number of medium-strong base sites in the catalyst, and raised in selectivity of methanol. Under reaction conditions of W/F(H2/CO2: 70/23) = 10 g∙h/mol, t = 200 ℃ and p = 3 MPa, using Cu-ZnO-Al2O3 treated under HCOOH/Cu = 0.8 (molar ratio), the CO2 conversion and the methanol selectivity were 6.7% and 76.3%, respectively.
Abstract(69) HTML(9) PDF 22123KB(17)
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g-C3N4, ZIF-8 and ZIF-8/g-C3N4 composite photocatalysts with different mass ratios were prepared by thermal polymerization method and in-situ deposition method, respectively. The structural properties of prepared samples were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS), etc. The above results showed that the ZIF-8/g-C3N4 composite did not destroy the original crystal structure and morphology of ZIF-8 and g-C3N4, and ZIF-8 formed a heterojunction with g-C3N4. The BET specific surface area of ZIF-8/g-C3N4 was improved more than 30 times compared with g-C3N4. The results of photocatalytic oxidation of NO showed that 12.5%-ZIF-8/g- C3N4 exhibited the best removal efficiency of NO, and no toxic intermediate NO2 production, and it had the most excellent photocatalytic activity, the removal efficiency of nitric oxide reached to 55.1%. The mechanism study showed that the formed heterostructure not only inhibited the recombination of photogenerated charge carriers, but also promoted the absorption of visible light and the adsorption of reactant molecular NO due to the synergy between ZIF-8 and g-C3N4, thus improving the photocatalytic oxidation performance of NO.
Abstract(5) HTML(6) PDF 10483KB(0)
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Sorption-enhanced steam methane reforming achieves one-step production of high purity hydrogen by in-situ removal of CO2. However, However, the volume change of the adsorption component CaO in the composite catalyst during the adsorption and desorption of CO2 generally caused the structure collapse of the composite catalyst. At the same time, the active component Ni would also be embedded by the generated CaCO3, resulting in the decline of catalytic and adsorption performance and seriously affecting the purity of hydrogen production. How to prepare bifunctional composite catalyst with high stability is one of the key problems to be solved in the industrial application of this technology. In this work, CaO-Ca3Al2O6@Ni-SiO2 composite catalyst was prepared by the self-template approach using the cationic surfactant-assisted etching mechanism. In the experiment of hydrogen production by adsorption enhanced CH4 / H2O reforming, the hydrogen production concentration over the composite catalyst reached 99.6%, and it still remained 97.3% after 10 cycles, which was closely related to the special structure of the prepared CaO-Ca3Al2O6@Ni-SiO2 composite catalyst. When the reaction was proceeded, the repeated expansion and contraction of CaO-Ca3Al2O6 volume in the composite catalyst was performed in the SiO2 cavity and would not cause the structure collapse of the composite catalyst. At the same time, the SiO2 coating on catalytic component Ni could prevent its agglomeration and deactivation during the decarburization and regeneration process. However, it was found that only part of the catalytic component Ni possessed a core-shell structure with Ni as the core and SiO2 as the shell, and there were some Ni directly loaded on the shell SiO2, leading to CH4 conversion dropping from 99.5% to 91.8% in 10 cycles.
Abstract(28) HTML(14) PDF 10821KB(8)
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The control of copper species on the surface of CuY catalyst is the key to improve the performance of methanol oxidation carbonylation to dimethyl carbonate. In this work, a series of CuY catalysts with different copper loads were prepared by solution ion exchange method, and the N2-physisorption, XRD, TEM, H2-TPR, XPS, NH3-TPD and CH3OH-TPD were used to characterize the microstructure of the catalyst. The effects of Cu-ammonia solution concentration and activation temperature for structure and properties of CuY surface copper were investigated. The results indicated that although the porosity of the catalyst was reduced by increasing the concentration of solution, the amount of copper was significantly increased from 2.21% to 9.95%, and the high dispersion of copper species was maintained, with the particle size less than 4 nm. The high concentration of solution exchange reduced the weak acid sites on the surface and inhibited side reactions to improve the selectivity of DMC. The copper species of low loading catalysts were mainly ionic copper. Increasing the content of copper increased the content of ionic copper, but also significantly increases the amount of CuOx, which could rapidly improve the catalytic performance, methanol conversion and DMC yield reached 9.07% and 396.27 mg/(g·h), respectively. The activation at suitable temperature promoted the diffusion of copper species from the external surface to the internal pores, increasing the exchange of Cu species with NaY and weakening the adsorption strength of methanol, which was conducive to the improvement of catalytic performance. Compared with low loading catalysts, high loading catalysts could be activated to obtain more Cu+ and CuOx at low temperature, thus showing higher catalytic performance. The results of this work provided a theoretical basis for the design and preparation of high-performance CuY catalysts.
Abstract(50) HTML(49) PDF 1789KB(7)
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Asphaltenes including asphaltene and preasphaltene (PAA) are the important products of the direct coal liquefaction process, whose structure and property are essential for the high-efficiency liquefaction and the subsequent utilization. The structure and property of PAA are closely related to the liquefaction conditions. Therefore, in this work, the effects of liquefaction temperature, residence time, pressure, and the ratio of solvent to coal on the structure and property of PAA obtained from mild liquefaction of Hami coal (named as HMPAA), were investigated in a batch autoclave with tetrahydronaphthalene as solvent. The structure features of HMPAA obtained under different conditions were characterized by elemental analysis, infrared spectroscopy and solid-state 13C-NMR. Thermal reactivity of HMPAA and the evolution curves of gas product during pyrolysis were analyzed by TG-MS. The results showed that the yield of HMPAA increased with decreasing reaction temperature, increasing pressure, decreasing residence time and increasing the ratio of solvent to coal. The highest HMPAA yield was 35.0% at 340 ℃, 3 MPa, residence time of 1 h, and the ratio of solvent to coal of 2∶1. The carbon structure of HMPAA consisted of aliphatic carbon and aromatic carbon, while the latter accounted for about 80%. Increasing liquefaction temperature was favorable to the formation of HMPAA with higher aromaticity. The aromatic condensation degree of HMPAA increased with extended residence time. The aromaticity and aromatic condensation degree of HMPAA decreased with the increase of the ratio of solvent to coal. The liquefaction pressures examined in this work had little effect on the structure and property of HMPAA. The pyrolysis of HMPAA started at about 250 ℃ and the peak temperature of maximum weight loss was between 400 ℃ and 500 ℃, and the final weight loss was over 40%. The thermal reactivity of HMPAA increased with decreasing liquefaction temperature and increasing the ratio of solvent to coal, and the change of pressure had little effect on the thermal reactivity of HMPAA.
Abstract(14) HTML(18) PDF 4711KB(2)
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The steam cracking of Fischer-Tropsch refined wax from the coal-to-oil process for producing linear α-olefin was carried out on a fixed bed reactor. The effects of feed composition, cracking temperature, residence time, water to wax ratio and recycling process on the feed conversion and products distribution were investigated and optimized. The factors such as cracking temperature and residence time have significant influence on conversion and LAO yield, and recycling can further improve the LAO yield. However, excess high cracking temperature and longer residence time result in the second reactions of produced LAO, which do not facilitate the reaction. Under the suitable process conditions over 50% of LAO yield are obtained.
Abstract(6) HTML(6) PDF 10138KB(4)
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Hydrogen energy is recognized as the most potential energy carrier in the 21st century. Reversible solid oxide cells (RSOCs) have attracted more and more attention due to their efficient use of hydrogen for power generation and efficient hydrogen production from water electrolysis. Numerous studies have shown that the polarization loss and decay of oxygen electrodes are the technical bottlenecks hindering RSOCs development. In this work, a 10% mol Sc-doped La0.6Ca0.4Fe0.7Sc0.1Ni0.2O3−δ (LCFSN) material was prepared, and the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) of this material were studied in detail by half cell. It was found that ORR catalytic activity of LCFSN was better than the OER. Ni-YSZ/YSZ/GDC/LCFSN full cells were assembled and their electrochemical performances in fuel cell mode (SOFC) and electrolysis cell mode (SOEC) were investigated in detail. The maximum power density can reach 1.471 W/cm2 at 800 ℃ with H2 as fuel. And the hydrogen production rate is as high as 627 mL/(cm2·h) at 750 ℃, 50%H2O and 1.3 V. In addition, the cell has no obvious degradation in the 100-h stability test and has good stability. These results are proved that LCFSN is a promising oxygen electrode material.
Abstract(1) HTML(0) PDF 17067KB(0)
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A series of Zn−Al oxides with different Zn/Al atomic ratios were prepared by the microwave-assisted evaporation-induced self-assembly (M-EISA) method, using industrial pseudo-boehmite as aluminum source. The prepared Zn−Al oxides were physically mixed with SAPO-18 zeolite and applied in tandem reaction for direct conversion of syngas to light olefins (${\rm{C}}_2^= -{\rm{C}}_4^=$). X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption, CO and H2 temperature-programmed desorption (CO-TPD, H2-TPD) and X-ray photoelectron spectroscopy (XPS) were selected for characterization. As the increase of Zn/Al ratio, the specific surface area and pore volume of Zn−Al oxides gradually decreased, while the average pore diameter firstly increased and then decreased. Compared with the ZnAl−IP prepared by the impregnation (IP) method, the ZnAl2Ox with the Zn/Al ratio of 1:2 had a high dispersion of Zn and formed the ZnAl2O4 spinel structure that produced more oxygen vacancies. The catalytic results show that the activity of Zn−Al samples prepared by M-EISA method firstly increased and then decreased as the Zn/Al ratio rose, while the ${\rm{C}}_2^= -{\rm{C}}_4^=$ selectivity gradually decreased. ZnAl2Ox sample exhibits the highest CO conversion of 34.8% and almost no obvious deactivation after 50 h’s reaction, furthermore, the catalytic performance is much better than that of ZnAl−IP sample.
Abstract(60) HTML(40) PDF 4634KB(11)
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ZSM-5@Beta core-shell molecular sieve was prepared by dynamic hydrothermal synthesis method using ZSM-5 adhered Beta seed crystals as the core phase, and polydiallyl dimethyl ammonium chloride (PDDA) was used as a coupling agent to adhere Beta seed crystals on the surface of ZSM-5. The structure and physical properties of composite molecular sieves were characterized by XRD, N2 adsorption-desorption, SEM, TEM, ICP, NH3-TPD and Py-FTIR. The catalytic performance of composite molecular sieves for alkylation of 2-methylnaphthalene (2-MN) with methanol was investigated. The results showed that ZSM-5@Beta composite molecular sieve prepared by this method had a core-shell structure, and the particle size was about 500 nm. Compared with mechanically mixed binary molecular sieve, core-shell molecular sieve had higher specific surface area and external surface area, lower acid strength and stronger acid center density. Through the construction of core-shell interface and hierarchical porous, the catalytic activity was improved by shell phase Beta molecular sieve with 12-membered ring channel, and the catalytic selectivity was improved by core phase ZSM-5 molecular sieve with 10-membered ring channel in the alkylation reaction of 2-MN with methanol. The 2,6-/2,7-DMN ratio in the products reached 1.35, and the yield of 2,6-DMN reached 4.29%.
Abstract(86) HTML(41) PDF 6158KB(13)
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Abstract(91) HTML(24) PDF 1552KB(17)
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A series of iron sulfide catalysts were prepared by pre-sulfidation at different temperatures and different hydrogen partial pressures, and their catalytic naphthalene hydrogenation activities were studied under 5 MPa 1% H2S-H2 atmosphere at 360 ℃. By means of XRD, MES, SEM-EDS, ICP and GC-MS, the effect of hydrogen on the pre-sulfidation process at different temperatures is studied. The results show that the introduction of hydrogen during the pre-sulfidation process facilitates the transfer of sulfur, thereby promoting the sulfidation. Different temperatures are favorable for the formation of Fe1−xS, but the effect of hydrogen is different at different pre-sulfidation temperatures. When pre-sulfidation at 50 ℃, the introduction of hydrogen can be beneficial to the transfer of sulfur, which increases the catalytic activity, a lot of elemental Fe and elemental S can be observed at this temperature; when pre-sulfidation at 150 ℃, the catalytic activity is the best. The content of elemental Fe decreases and no elemental S is observed. With the increase of hydrogen partial pressure, the hydrogenation conversion rate of naphthalene increases from 60.6% to 69.1%. When pre-sulfidation at 300 ℃, the catalytic activity decreased to varying degrees. Hydrogen reduces the sulfur on the catalyst surface to a low valence state and crystalline Fe3O4 is observed inside the catalyst particles, which is not conducive to the transfer of sulfur.
Abstract(64) HTML(37) PDF 1107KB(9)
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In this paper, the variation of pore structure of three typical coal char with gasification temperature and its effect on subsequent gasification reaction were studied by means of Drop Tube Furnace (DTF) and thermogravimetric analyzer (TG). The results show that the pore structure parameter of coal char increases with the increase of temperature, which characterizes the shrinkage and closure of pores at high temperature. the local decrease of pore structure parameter near the ash melting point indicates the blockage and cover of pore structure caused by ash melting at high temperature. The growth ratio is defined as the ratio of the difference between the maximum gasification reaction rate and the initial reaction rate to the initial reaction rate. when the pore structure parameter is greater than 2, there is a linear relationship between the growth ratio and the pore structure parameter, and the growth ratio increases with the increase of the pore structure parameter. When the pore structure parameter is less than 2, the relationship between the growth ratio and the pore structure parameter is not obvious. The experimental results also show that the high content of alkali metals will have a great effect on the gasification rate, which makes it difficult to accurately fit the experimental data curve with the existing model, and the value of the growth ratio will not be affected by it. It is feasible to couple the growth ratio to the gasification model to improve the robustness of the model.
Abstract(85) HTML(20) PDF 11127KB(26)
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The capture and utilization of carbon dioxide (CO2) have attracted much attention in recent years; in particular, the direct hydrogenation of CO2 to light aromatics has been considered as a potential route to produce high value-added chemicals. However, it is still a big challenge to adjust the aromatic distribution and achieve a high selectivity to the targeted products. In this work, a bifunctional catalyst that combines the Cu-modified Fe3O4 and the chain-like ZSM-5 zeolite is used for the hydrogenation of CO2 to light aromatics. The catalyst components were characterized by XRD, SEM, TEM, ICP-AES, Py-IR and N2 adsorption-desorption; the effect of acid density and length-to-diameter ratio (b-axis/ a-axis) of zeolite moiety on the selectivity and distribution of aromatic products was then investigated. The results indicate that the chain-like ZSM-5 zeolite moiety with high acid density and appropriate length-to-diameter ratio can promote the C–C coupling for CO2 hydrogenation and inhibit the formation of CH4, which can improve the selectivity to aromatics and the space time yield (STY) of toluene.
Abstract(52) HTML(29) PDF 15595KB(4)
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Microwave-assisted heating method was used to rapidly prepare three-dimensional hollow nickel-cobalt hydroxide (Ni-Co LDH) by using zeolite dimethyl imidazolium cobalt (ZIF-67) as template and cobalt source. The effect of microwave reaction time on the morphology and electrochemical properties of the materials was investigated. X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and specific surface and aperture analyzer (BET) were used to investigate the effect of microwave reaction time on the structure and morphology of the samples. The electrochemical properties of Ni-Co LDH electrode materials were analyzed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results showed that the electrochemical properties of Ni-Co LDH-15 min electrode were the best. The specific capacitance was 2371.0 F/g at 0.5 A /g. The Ni-Co LDH-15 min also possessed excellent capacity retention of 78.5% when the current density increased by 20 times. An asymmetric supercapacitor (Ni-Co LDH//AC) was assembled by using Ni-Co LDH as the positive electrode and AC as the negative electrode. The Ni-Co LDH//AC device delivered a high energy density of 19.71 Wh/kg at the power density of 448.05 W/kg. Furthermore, the capacitance retention rate still maintained 88.7% after 5000 cycles. These results showed that Ni-Co LDH was a kind of electrode material for supercapacitor with excellent electrochemical performance and practical application potential.
Abstract(47) HTML(76) PDF 747KB(11)
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C5 and C7 asphaltene were separated from paraffin base Yumen atmospheric residue and naphthene base Merey atmospheric residue by n-pentane and n-heptane respectively using the method of SARA. The structure parameters and functional groups analyzed and characterized systematically by VPO, 1H-NMR, FT-IR and elemental analysis, in order to comparative studied the differences in asphaltene structure of different residues and asphaltene obtained by different precipitants. The results showed that there was consistent in the functional groups of different asphaltenes basically, but there was some differences in the unit structure of different asphaltene. There were significantly higher molecular weight, smaller HAU/CA value and higher condensation degree of Yumen paraffinic asphaltenes than that of Merey naphthenic asphaltenes. With the increased of carbon chain of precipitants, the yield (the yield of n-heptane asphaltene is about 80% of n-pentane for the some feedstook) and the H/C of asphaltene decreased, the molecular weight of asphaltene increased. C7 asphaltenes have higher aromatic carbon ratio ($f$A) and more structure units than that of C5 asphaltene. More saturated structure is exist in various asphaltenes and the saturate carbon fraction is about 0.5.
Abstract(57) HTML(34) PDF 1088KB(8)
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The NO emission characteristics of bituminous coal/semi-coke blends were investigated in an electrical-heating circulating fluidized bed experimental rig. Meanwhile, the distribution and occurrence forms of N element in fuels were also analyzed in order to enhance the understanding of NO emission characteristics. The results indicated that the volatile-N and char-N in Shenhua bituminous coal (BC) accounted for 53.85% and 46.15%, respectively, and the majority of N in semi-coke (SC) was char-N. During the combustion, the volatile-N released quickly and was easy to be reduced in the dense-phase zone, whilst the char-N released relatively slowly. Hence, the NO emission concentration of SC was obviously higher than that of BC. After blending SC with BC, the NO emission decreased with the SC blending ratio and the interactions between component fuels could suppress the NO emission as well. The NO emission of SC and BC showed the opposite variation tendencies with the combustion temperature, and it increased with the temperature for blends with 40% and 80% BC. Besides, the NO emission of BC, SC and their blends all increased with the excessive air coefficient and primary air ratio.
Abstract(86) HTML(39) PDF 12262KB(19)
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Developing the oxygen carriers with large oxygen carrying capacity, high reactivity, and strong cycle stability is one of the research focuses in the chemical looping combustion technology. In this study, the effect of spinel-structured K3FeO4 on the reactivity of Fe-based oxygen carrier was investigated based on the density functional theory involving the electronic structural properties such as the density of states, adsorption energy, and activation energy. The results show that when the K3FeO4 is loaded on the α-Fe2O3(001) surface, the microscopic electronic structure of α-Fe2O3(001) surface is changed, the Fe–O bond on the surface is elongated, the O-p orbital electrons transition to a higher energy level, and the electron activity of oxygen atom is improved. The energy barriers of CO reaction with the surface lattice oxygen show a decreasing trend at the three lattice oxygen sites after the loading of K3FeO4 which can improve the activity of surface oxygen atoms and make the breakage of Fe–O bond via elongation easier with less energy required . In addition, CO can bond with the more active oxygen atom in K3FeO4, and also can combine with the O2 atom to form a new C–O bond, by which CO is adsorbed on the surface in the form of bidentate carbonate that would be decomposed and released as CO2.
Abstract(60) HTML(7) PDF 11182KB(5)
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A series of nFe(III)Ox/ZnO photocatalysts with different Fe contents was prepared by impregnation method, and the samples were characterized by XRD, N2 physisorption, TEM, XPS, UV-vis and PL. It was found that by changing the concentration of Fe species in the impregnation solution, the Fe content in the final sample could be properly adjusted. Within the scope of this work, the loading of Fe does not cause significant changes in the phase, morphology, and porous structure of the ZnO support. However, the electronic state of the catalyst surface was altered considerably, with more O-vacancies were introduced. Fe species enhanced the separation of photo-induced electron-hole pairs, which was responsible to improve the performance of photocatalytic CH4 conversion. Through the optimization of solvent volume, H2O2 concentration and reaction time, the 0.1Fe(III)Ox/ZnO sample showed the best performance over which the yield and selectivity of liquid oxidation products (CH3OH, CH3OOH, HCHO) was 5443 μmol/(gcat·h) and 99%, respectively. Based on radical quenching experiments, it was found that the ·${{\rm{O}}_2^-}$radicals derived from H2O2 played a major role for the activation of CH4 to ·CH3.
Abstract(30) HTML(8) PDF 1711KB(10)
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Char gasification reactivity plays a vital role in the design of a gasifier. In this paper, a series of char were prepared by pyrolysis at 900−1100 ℃ in a fluidized bed and a drop tube reactor with a lignite as the sample, and the physico-chemical structure and CO2 gasification reactivity of chars were studied by X-ray diffractometer (XRD), Raman spectrometer, static physical adsorption instrument and fixed-bed reactor. The results showed that the gasification reactivity of char in the fluidized bed and drop tube reactors mainly depended on its chemical structure. In the two reactors, as pyrolysis temperature increased, the polycondensation reactions of char were deepened, resulting in the increasing crystalline size (aromatic sheet stacking height Lc, average diameter La) and larger ring to smaller ring ratio ${I_{\rm{D}}}/{I_{({{\rm{G}}_{\rm{r}}}{\rm{ + }}{{\rm{V}}_{\rm{r}}}{\rm{ + }}{{\rm{V}}_{\rm{1}}})}}$ of char. Therefore, the gasification reactivity of char was decreased with increasing pyrolysis temperature. The crystalline size and larger ring to smaller ring ratio ${I_{\rm{D}}}/{I_{({{\rm{G}}_{\rm{r}}}{\rm{ + }}{{\rm{V}}_{\rm{r}}}{\rm{ + }}{{\rm{V}}_{\rm{1}}})}}$ of char in the fluidized bed reactor were lower at the same pyrolysis temperature, and their variations with increasing pyrolysis temperature were smaller compared those in the drop tube reactor, resulting in the lower gasification reactivity of char and the smaller change of gasification reactivity of char with increasing pyrolysis temperature. Those were mainly due to the long residence time of char and strong interactions of char and volatiles in the fluidized bed reactor, deepening the degree of polycondensation reaction of char.
Abstract(50) HTML(58) PDF 1168KB(12)
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A series of TiO2-supported V-W bimetallic catalysts were prepared by incipient wetness impregnation method. The effects of V/W ratios on the catalytic combustion performance for chlorobenzene were investigated. The results showed that proper W doping (5V5W-Ti and 3V7W-Ti) improved the catalytic combustion activity of chlorobenzene and the selectivity of HCl. In combination with BET, XRD, XPS, H2-TPR, NH3-TPD and Py-FTIR characterizations, it indicated that higher activity for chlorobenzene oxidation was attributed to the high dispersion of the active species and the abundant surface adsorbed oxygen. In addition, moderate doping of W significantly enhanced the surface acidity of catalysts, especially strong acids and Brønsted acids, and thus improved the selectivity to HCl in the products.
Abstract(69) HTML(45) PDF 1172KB(7)
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CO2 electrocatalytic reduction to synthesize highly value-added fuels provides a sustainable path for CO2 conversion and utilization. Nevertheless, the development of electrocatalysts with high catalytic activity and product selectivity remains a major challenge. In this work, copper-doped FeS2 catalysts (CuxFe1−xS2) were prepared for CO2 electrochemical reduction. The physicochemical properties of the catalysts were studied by XRD, XPS, SEM and other characterization analysis methods. Experimental results show that Cu doping can control the size of the catalyst nanosheets and inhibit the oxidation of FeS2 in the air. Cu0.33Fe0.67S2 shows better catalytic activity for CO2 electrocatalytic reduction than FeS2. In the potential range of (−1.5) − (−1.6) V vs. RHE, the total efficiency of carbon-containing products of CO2 electrocatalytic reduction is 50.8% and its current density is 23.8 mA/cm2, which increases by 71.2% compared with FeS2 catalyst. The Faradaic efficiency of Cu0.09Fe0.91S2 to produce C3H6 at −1.3 V vs. RHE is 21.8%, which is significantly higher than the value reported in the current literature. Thus, CuxFe1−xS2 is regarded as an excellent electrocatalyst for CO2 reduction.
Abstract(17) HTML(24) PDF 8761KB(4)
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A series of Co-doped Mn oxide catalysts with different Co/Mn molar ratios were prepared by co-precipitation method, which was systematically characterized by XRD, SEM, H2-TPR and NH3-TPD etc. Co-doped Mn oxide catalysts are evaluated for NH3-SCR activity and resistance to SO2 and/or H2O, and the Co(1)-MnOx catalyst with Mn/Co molar ratio of 1:1 performs the best catalytic performance, which achieved higher than 90% NOx conversion in the temperature range of 100−275 °C and possessed better SO2 and H2O resistance. The Co(1)-MnOx catalyst presented a sphere-like structure possessing a relatively large surface area. Doping of cobalt greatly improved the high-valent metal ions and chemisorbed oxygen content of Co(1)-MnOx catalyst surface, and the catalyst possessed abundant active species and acid sites and apparent activation energy of the catalyst was reduced, which makes Co(1)-MnOx a highly effective NH3-SCR catalyst.
Abstract(18) HTML(12) PDF 7778KB(5)
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Oct@PMMA microcapsules phase change materials were synthesized by the emulsion polymerization method, and the energy storage performance and thermal stability was improved by selecting PVP as dispersing agent and PETRA as cross-liking agent; The chemical and physical properties of the microcapsules were characterized by FT-IR, XRD, DSC and TG. The results showed that the thermal performance and yield were improved by PVP, increasing the stability and dispersibility of emulsion droplets, the enthalpy in phase transition was 105.6 J/g and the yield reached 98.01%, the thermal stability was enhanced by PETRA and the decomposition temperature is up to 175 ℃.
Abstract(57) HTML(10) PDF 19957KB(15)
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N-doped core-shell nanorods (N-MoP/NC-8) hydrogen evolution catalyst was synthesized by gas-solid reaction in-situ phosphorization of molybdenum trioxide-ethylenediamine organic-inorganic hybrid materials (MoO3/EDA). Through the characterization of the materials by various analytical techniques, it is found that N-MoP/NC-8 is composed of N-doped molybdenum phosphide (MoP) coated by N-doped carbon layer. The introduction of electronegative atoms regulates the electronic structure of the active phase and combination between carbon layer and MoP limits the internal agglomeration of MoP, produces larger pore volume and surface area. With dual regulation, it showed the better hydrogen evolution performance (in 0.5 M H2SO4 solution, overpotential of 92 mV and Tafel slope of 68 mV/dec at 10 mA/cm2 current density), good charge transfer ability and durability of at least 20 h.
Abstract(55) HTML(48) PDF 29073KB(20)
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SSZ-13 zeolites were synthesized by conventional hydrothermal method and the Cu-SSZ-13 zeolite catalysts were then prepared by Cu ion-exchange and used in the selective catalytic reduction of NOx with NH3 (NH3-SCR); the effect of various preparation parameters including the organic template agent (OSDA) dosage, silicon source, aluminum source, H2O/Si ratio, Si/Al ratio and aging time on the morphology, crystal size, acidity, state of Cu2+ sites and the catalytic performance of Cu-SSZ-13 in NH3-SCR were investigated. The results indicate that silica sol (JN25) and Al2(SO4)3 are appropriate as the silicon and aluminum sources, respectively, to prepare SSZ-13 zeolites with small crystals, high crystallinity and high activity in NH3-SCR. With the increase of Si/Al ratio, the crystal size of SSZ-13 increases and the copper content loaded on Cu-SSZ-13 decreases, leading to the degradation of NH3-SCR activity. A high H2O/Si ratio of 88 is conducive to forming larger SSZ-13 crystals, whilst increasing the OSDA dosage is beneficial to improving the crystallinity, reducing the crystal size, and accordingly enhancing the catalytic activity of Cu-SSZ-13 in NH3-SCR. In addition, a relatively longer aging time can also reduce the crystal size and raise the catalytic activity of Cu-SSZ-13. In particular, the Cu-SZ13-A10 zeolite catalyst synthesized with a Si/Al ratio of 10 (with the gel composition of 1SiO2 : 0.01Al2(SO4)3 : 0.3NaOH : 0.4SDA : 88H2O; JN25 as silicon source and aging for 2 h) exhibits high activity in NH3-SCR; under a high GHSV of 240000 h−1, the NO conversion reaches 60% at 200 ℃ and keeps at 100% in the moderate-high temperature range. These results should be useful for the regulation of SSZ-13 zeolite morphology and the preparation of high efficient Cu-SSZ-13 catalysts for NH3-SCR.
Abstract(58) HTML(42) PDF 3384KB(9)
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In this study, a small-sized CoNi bimetallic co-catalyst was synthesized in situ on g-C3N4 nanosheets using a simple chemical reduction method. The physicochemical properties of the prepared CoNi/g-C3N4 were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV–Vis DRS), x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and electrochemical impedance spectroscopy(EIS). The photocatalytic degradation of RhB showed that the CoNi bimetallic co-catalyst could effectively improve the separation efficiency of photogenerated carriers in g-C3N4, thus enhancing the photocatalytic activity. The highest catalytic activity of CoNi/ g-C3N4 was achieved when the molar ratio of CoNi was 1∶1, with a degradation rate of 0.01633 min−1, which was 3.9 times higher than that of normal g-C3N4 under visible light irradiation. The photocatalyst maintained good photocatalytic activity after five cycles. The main active species of the reaction is the superoxide radical (·O2).
Abstract(53) HTML(117) PDF 15526KB(9)
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The hydrolysis process of silicon source tetraethyl orthosilicate(TEOS) was tracked by FT-IR analysis, and the effect of hydrolysis time on the distribution of titanium species in TS-1 zeolites was discussed through XRF and UV-Vis. The catalytic oxidation performance of TS-1 zeolite was tested by 1-hexene epoxidation as a model reaction. The results showed that moderate hydrolysis of tetraethyl orthosilicate can effectively inhibit the formation of extraframework Ti and increase the content of framework Ti. However, shorter or longer hydrolysis time is not conducive to the entry of titanium into the skeleton and reduce the catalytic performance of TS-1 zeolites. TS-1 prepared with 2 hours TEOS hydrolysis time has the best catalytic performance for epoxidation of 1-hexene. Under the reaction conditions of atmospheric pressure and 60 ℃, the conversion of 1-hexene can reach 37.5% and the selectivity of 1,2-epoxy hexane can be maintained at about 85%, and the results had a guiding role for the development of olefin epoxidation catalyst.
Abstract(71) HTML(15) PDF 3649KB(11)
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In this study, the Co-WOx catalyst was successfully prepared by directly introducing Co2+ dopant in a dynamic solvothermal synthesis process, and the obtained Co-WOx was used for the catalytic epoxidation of 1-hexene. The structures of WOx before and after the doping were analyzed by XRD, SEM, TEM, Raman, XPS as well as in-situ NH3-IR. The results show that the doping of Co2+ has not obvious effect on the crystal phase and main growth direction of WOx, but can effectively reduce the content of Brönsted acid (B acid) site on the surface of WOx catalyst and increase the content of oxygen vacancy at the same time. In the epoxidation reaction, the obtained Co-WOx catalyst (Co/W = 0.1) can increase the selectivity of 1,2–epoxyhexane from 26.9% of pure WOx to 55.7% with a 5.3% decrease in 1–hexene conversion. The improvement of Co-WOx performance is mainly attributed to two aspects: (1) the reduction of B acid site on the surface of WOx inhibits the ring opening hydrolysis of 1,2-epoxyhexane; (2) The increase of oxygen vacancies on the surface of WOx promotes the activation of H2O2, ensuring that the conversion rate of 1–hexene does not decrease significantly, and an increase in the utilization of oxidant H2O2 by 13.5%. Combined with the characterization results and reaction data, the epoxidation mechanism of 1–hexene with W-O-OH as active intermediate is proposed.
Abstract(45) HTML(29) PDF 6062KB(19)
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Abstract(29) HTML(11) PDF 1558KB(8)
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In this paper, four kinds of LaFeO3 perovskite catalytic materials with different ball milling time were prepared by solid phase milling method and used to catalyze the wet air oxidation of phenol. The effect of milling time on the performance of LaFeO3 perovskite catalyst for wet air oxidation of phenol aqueous solution was investigated. LaFeO3 perovskite catalytic materials were characterized by XRD, H2-TPR, TG-DTA, FT-IR, N2 physical adsorption and XPS. The results show that when the reaction temperature is 200 ℃, the air pressure is 5 MPa and the initial concentration of phenol is 4000 mg/L, the final COD removal rate of LaFeO3-6 catalytic material is 94.5% after catalytic oxidation of 240 min.
Abstract(16) HTML(31) PDF 10609KB(1)
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Based on the complicated preparation of current mainstream diesel vehicle exhaust gas denitration catalysts, we designed an in-situ deposited composite oxide catalyst. The CeO2-WO3 mixed oxide catalysts loaded on the titanium mesh was prepared by electrodeposition and hydrothermal methods and applied to the Selective Catalytic Reduction denitration of diesel vehicle exhaust. Denitration performance of the catalysts were tested by a fixed bed reactor, and the influence of different electrodeposition time of CeO2 was investigated. The denitration test results demonstrated that 20 min was the best electrodeposition time of CeO2 (100% NOx conversion at 250−350 ℃). The high dispersion of active CeO2 on WO3 promoted the synergistic effects among different components. The as-prepared catalysts were characterized by SEM, XRD, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. It is evidenced that the loading of Ce3+ was successfully introduced via loading of CeO2, which enhanced chemisorption of oxygen. Meanwhile, increased acidity of CeO2-WO3 composite catalyst was observed, including both weak acid and medium-strong acid sites, which improved the co-adsorption of NH3 on Lewis acid and Brønsted acid simultaneously and facilitated the denitration process. Through the characterization of in situ DRIFTS, it is elucidated that the NH3-SCR reactions are mainly carried out following Eley—Rideal (E—R) pathway in the medium-temperature range (250−350 ℃).
Abstract(51) HTML(26) PDF 7534KB(8)
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Nitrogen-doped carbons (Nano-NC) are often employed as functional supports for boosting oxygen reduction reaction (ORR) over Pt-based catalysts, however, the mechanism of N doping on the adsorption and activation of molecular oxygen on Pt active sites is still not clear. Herein, Nano-NCs as the supports were prepared by a facile NH3 antipyretic method, which allowed to tune the kinds of nitrogen species in carbon matrix and their contents by adjusting the NH3 antipyretic temperatures.With such an exquisite control, the Pt nanoparticles loaded on the as-obtained Nano-NC showed an optimal Pt particle size (2.10 nm), a higher content of Pt0, a large electrochemically active surface area, and fast electron transport ability. As a consequence, the Pt/Nano-NC-800 catalyst with the optimal N-doping showed an outstanding ORR performance with half-wave potential of 0.80 V vs. RHE, limit diffusion current of 5.37 mA/cm2 and improved methanol/CO anti-poisoning, which is superior to the commercial Pt/C catalyst (20%, JM), and most of previously reported Pt-based catalysts. This work may pave a way for the design of the advanced supports for Pt-based catalysts for the ORR applications.
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Two industrial wastes, spent FCC catalyst (sFCCc) and blast furnace ash (BFA), were used as catalysts in the fast pyrolysis of sawdust, and the catalytic pyrolysis reaction characteristics of sawdust in the temperature range of 400−700 ℃ were explored. The results showed that both catalysts promoted the conversion from liquid products to gas products, and the highest gas yield was 52.60% at 700 ℃ catalyzed by BFA. The sFCCc had stronger deoxygenation activity at 500−600 ℃, and higher CO and CO2 production in gas products, while BFA had higher polycondensation and dehydrogenation activity at 600−700 ℃, and promoted the formation of polycyclic aromatic compounds and H2. Pyrolysis oil was mainly composed of phenols. sFCCc promoted the conversion of methoxyphenol to benzenediol. FT-IR analysis of pyrolysis oil showed that sFCCc promoted the removal of C−O and C=O, resulting in the decrease of acid and ester compounds and the increase of CO2 yield.
Abstract(64) HTML(29) PDF 21266KB(20)
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Interface regulation is an effective strategy to improve the interaction between carrier and active metal center, which can improve the catalytic activity and oxygen storage capacity of catalysts. In this paper, Ni/CeO2 catalysts with four kinds of CeO2 morphologies (nanorods, nanocubes, nanoctahedrons and nanopolyhedrons) have been successfully synthesized, and the structure dependence of the catalysts for the low temperature chemical looping dry reforming of methane (CL-DRM) was investigated. The material characterization showed that Ni species were highly dispersed on the surface of CeO2 carrier, and some Ni ions entered CeO2 lattice, resulting in the increase of oxygen vacancy. The results of the chemical looping dry reforming (CL-DRM) showed that the Ni/ceria-rods catalyst had the highest reducibility, the most oxygen vacancies and the highest oxygen storage capacity. The structure of Ni/ceria-polyhedra catalyst was irregular CeO2 nano single crystal of about 10.3 nm. The Ni/ceria-polyhedra had high specific surface area and high reducibility, showed low-temperature methane reaction activity, and showed the highest redox activity and redox stability in low-temperature chemical looping dry reforming of methane at 550 ℃. This study provides a new strategy for the design of efficient metal/CeO2 Catalysts, which is expected to promote the application of cerium-based catalysts in chemical looping technology.
Abstract(39) HTML(26) PDF 17140KB(4)
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Co/HZSM-5 catalyst was fabricated for catalytic dehydrogenation of propane to propylene, which was pretreated to allow the reaction to react at low temperatures. A response surface approach was employed to examine the effect of process conditions on the reaction. The morphological and oxidative performance of Co/HZSM-5 was characterized by XRD, XPS, SEM, NH3-TPD, H2-TPR, and nitrogen physical absorption-desorption. Besides, the in-situ catalyst performance was evaluated by a fixed-bed reactor. Combining the actual experimental conditions, the optimal process conditions parameters obtained by the response surface method were as follows: a reaction temperature of 461 °C, a Co loading of 2.4%, and a GHSV of 4300 h−1. At this point, the propylene yield reached 27.7% and the corresponding propylene selectivity was up to 93.8 %.
Abstract(73) HTML(32) PDF 14054KB(13)
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High-temperature solid oxide electrolysis of CO2 is an efficient, green and flexible method of CO2 conversion and utilization, which can realize CO2emission reduction and renewable energy power conversion and storage at the same time. It has great applied prospects in the fields of CO2 resource utilization and manned deep space exploration. And with the increasingly severe greenhouse effect and energy crisis, high-temperature solid oxide electrolysis of CO2 is gradually becoming a research hotspot in the field of international environment and energy. This review analyzes and summarizes the basic principles, key materials, performance degradation, stacks, application fields, efficiency, economy and emission reduction potential of high-temperature solid oxide electrolysis of CO2. Moreover, in view of the current problems and constraints that limit the industrial application of solid oxide electrolysis of CO2, multifaceted suggestions and strategies are put forward. This review aims to attract extensive attention in many fields and departments in China, and to promote industrial application of CO2 electrolysis in solid oxide electrolysis cell.
Abstract(57) HTML(43) PDF 2893KB(3)
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Herein, SiO2 supported metallic Ni (Ni/SiO2) and bimetallic Ni-Zn (NixZn/SiO2) (x represents the Ni/Zn atomic ratio) catalysts were prepared by the incipient wetness impregnation method and their activities were tested in vapor phase hydrodeoxygenation (HDO) of anisole under 0.1 MPa. It has been found The characterization results show that the Ni-Zn alloy forms in NixZn/SiO2 after reduction at 550 °C, and the a suitable Ni/Zn atomic ratio (30) leads to smaller metal crystallites alloy particle size and consequently more H2 adsorption amount than others. In the HDO reaction, the formation of Ni-Zn alloy facilitates the direct deoxygenation pathway and suppresses CO methanation and C−C bond hydrogenolysis, which is ascribed to the isolation effect of the Ni atoms by the oxophilic Zn ones. Ni30Zn/SiO2 gives not only higher anisole conversion but also higher selectivity to benzene than Ni/SiO2. Therefore, the introduction of a suitable amount of oxophilic Zn in Ni/SiO2 promotes the HDO of anisole to benzene. Finally, we suggest propose that the Ni30Zn/SiO2 deactivation is related to the surface oxidation of Ni-Zn alloy and carbonaceous deposit carbon deposition on the catalyst surface.
Abstract(29) HTML(23) PDF 21708KB(6)
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Oxidation treated carbon materials for exploiting highly efficient and stable loaded catalysts have been proven to be valid. In this work, the surfaces of carbon aerogels (CA) were functionalized with different oxidizing agents, i.e., H2O2 and HNO3. A series of Ru-supported catalysts on carbon aerogels (CA) with/without functionalized were prepared by the impregnation strategy. The impact of oxidation treatment on the texture features of carbon aerogels, the types and contents of formed surface oxygen-containing functional groups, the metal-support interactions and the Fischer-Tropsch synthesis reaction performances of i the catalysts were systematically investigated. Our results showed that Ru/CA catalyst without oxidation treatment displayed the highest initial activity but the poor stability, while the Ru/CA−H2O2 catalyst exhibited excellent activity and C5+ selectivity. The oxidation treatment increased the carbon aerogels defects, thereby broadening the specific surface area. The increased content of oxygen-containing functional groups on the surface enhanced the interaction between the support and Ru nanoparticles and improved the stability of the catalyst. Nevertheless, the excessive oxygen-containing functional groups on the surface decreased the activity and the C5+ selectivity of carbon aerogels-loaded Ru catalysts.
Abstract(28) HTML(12) PDF 868KB(4)
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Direct methanol fuel cell (DMFC) is a potential commercial fuel cell technology that is presently hindered by the expensive noble metal materials of the anode. Developing a method to obtain a uniformly dispersed metal phosphide catalyst with narrow size distribution is still a challenge. In this work, cobalt oxide was deposited on carbon cloth (CC) through atomic layer deposition (ALD), then cobalt phosphide was obtained after the phosphorization process. By changing the number of ALD-based ozone pulses (ALD-O3) for CC, the nucleation and growth modes of cobalt oxide (ALD-CoOx) on the CC were regulated, and CoPx nanoparticles with small particle size and uniform distribution were obtained. The optimized CoPx-based catalyst with 40 cycles of ALD-O3 treatment (CoPx/40-CC) exhibits excellent activity (153 mA/cm2) toward methanol electrocatalytic oxidation reaction in the alkaline solution, which is higher than the catalyst prepared by impregnation (Imp-CoPx/CC), although the CoPx loading of CoPx/40-CC is lower than that of Imp-CoPx/CC. The results indicate that the enhanced activity benefits from the small particle size and the uniform CoPx distribution, which promote the electron-transfer and mass transport kinetics of the methanol electro-oxidation process.
Abstract(79) HTML(50) PDF 36639KB(16)
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In this work, a 3D ordered mesoporous structure MoS2/C composite with few-layered MoS2 was synthesized by liquid phase nanocasting method, using SBA-15 as hard template, sucrose as carbon source and ammonium molybdate tetrahydrate (ATTM) as MoS2 precursor. The limiting effect of amorphous carbon makes thin MoS2 slices evenly dispersed, and avoids occurrence of MoS2 agglomeration, resulting in the exposure of a large number of MoS2 edges as active sites. The 3D ordered mesoporous structure of the catalyst provides high specific surface areas and ensures transport channels for material and electron for electrochemical HER. As a result, the composite demonstrates efficient HER activity with an overpotential of 165 mV at current density of 10 mA/cm2 and a Tafel slope of 91 mV under acidic conditions. This study provides a basis for constructing 3D HER catalyst with high specific surface area and few-layered MoS2 uniformly dispersed.
Abstract(130) HTML(30) PDF 5068KB(13)
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Developing highly active and non-noble-metal electrocatalyst for oxygen evolution reaction (OER) is expected to accomplish efficient water splitting hydrogen production and promote the commercial utilization of hydrogen energy. We in-situ fabricated bimetallic NiC2O4-Co electrocatalyst on nickel foam (NF) by a facile one-step solvothermal method in this work. With an optimized molar ratio, NiC2O4-Co1 self-supported electrocatalyst presents superb OER performance with a low overpotential of 278 mV at 10 mA/cm2 and a Tafel slope of 65 mV/dec, accompanied by excellent stability in 1 M KOH electrolyte. The superior catalytic activity of bimetallic NiC2O4-Co electrocatalyst is attributed to optimized electronic structure, high specific surface area, rapid interfacial charge transfer and the synergistic effect between Ni sites and Co sites during OER process.
Abstract(33) HTML(36) PDF 2980KB(16)
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Naphthalene is an important component of high temperature coal tar, and its content can reach more than 10%. Catalytic polycondensation of naphthalene was an effective way to prepare mesophase pitch and functional carbon materials. In this work, anhydrous AlCl3 was used as a catalyst to systematically study the polymerization process of naphthalene under atmospheric pressure below 170 ℃. At 110 ℃, the polymer was mainly composed of tricyclic compounds and there was only 29.5% of the heavy products. At 150 ℃, four to five peri-condensed aromatic compounds were the main components, and the content of medium components remained about 50%. There was a large number of six-ring aromatic core at 170 ℃, and the conversion rate of naphthalene was up to 90.7%. The products had good flow properties, which could facilitate the high-temperature thermal polycondensation and subsequent graphitization process. When the molar mass ratio of AlCl3 to naphthalene was 1∶100, it was found that the second to seventh order naphthalene oligomers could be obtained by the simulation of the short chain oligomerization of naphthalene. Moreover, acetylene and methylnaphthalene can be produced by catalytic pyrolysis of naphthalene when the molar mass ratio increased to 10∶100. The mechanism of “Oligomerization–Pyrolysis–Aromatization” was proposed to explain the molecular transformation from naphthalene to pitch, which provided experimental basis for the production of mesophase pitch precursor.
Abstract(47) HTML(20) PDF 1368KB(7)
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A series of Cu-Ce/SAPO-34 Bimetallic Zeolite catalysts were prepared by impregnation method. The performance of the different quality Cu/Ce ratios zeolite catalysts for selective catalytic reduction of NO was investigated in a catalyst evaluation device. XRD, SEM, NH3-TPD, XPS, in-situ DRIFTS were used to characterize and analyze the catalysts. The results show that the modified Cu-Ce/SAPO-34 catalyst has good denitration performance and wide activity temperature window. When the content of Cu and Ce is 4%, the zeolite catalyst has the best denitration efficiency, the denitration efficiency is 80% at 325-500℃, and the NO conversion rate is more than 99% at 400-500℃. The bimetallic oxide species were highly dispersed on the surface of the catalyst, and the crystal structure of SAPO-34 was not affected, and the interaction between the active substance and the support was good. 4Cu-4Ce/SAPO-34 has an appropriate amount of acidic sites, and this mixture has positive effects on the denitrification performance and stability of the catalyst, and follows the e-r mechanism in the NH3-SCR reaction process.
Abstract(50) HTML(27) PDF 1790KB(4)
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A class of TiO2 modified VPO catalysts were prepared by organic solvent-heating method in the present work. The catalysts were characterized by TEM, XRD, XPS, NH3-TPD and CO2-TPD techniques. The catalytic performances were evaluated in the aldol condensation of acetate acid and formaldehyde to acrylic acid in fixed-bed reactor. The results showed that the addition of TiO2 significantly changed the proportion of V content forming V5+ and V4+ ion pair to total V with the unmodified VPO catalyst. As the precursor of TiO2 is rutile phase and Ti/V molar ratio is 2.0, the proportion of V content forming V5+ and V4+ ion pair to total V reaches the maximum, resulting in the best acrylic acid yield (18.0%) and acrylic acid space-time yield (6.61 mmol/(g·h)). It indicates that for the VPO catalyst modified by TiO2, the redox cycle of V5+ and V4+ ion pair plays a major role in the catalytic reaction of formaldehyde and acetate acid to acrylic acid.
Abstract(42) HTML(24) PDF 8492KB(1)
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TiO2/GO with different graphene oxide (GO) composite ratios were prepared by hydrothermal method and characterized by SEM, TEM, XRD, UV-VIS, XPS, FTIR, Raman and photocurrent. The results show that both TiO2 and GO/TiO2 crystal are anatase type. When GO is prepared by hydrothermal reaction with butyl titanate, part of GO is reduced to reduced graphene oxide (RGO), which is closer to graphene, which is conducive to photoelectron transfer. Compared with pure TiO2, the composite catalyst TiO2/GO has a smaller grain size and a higher ratio of adsorbed oxygen/lattice oxygen, which is beneficial to the oxidation of NO, the band gap is reduced, the ability to absorb visible light is stronger, and the photoelectron response ability is improved and has more excellent photocatalytic performance. The photocatalytic denitration performance of the composites was evaluated under visible light. When the GO composite ratio is 1.5wt% (wt, mass fraction), the photocatalytic denitration performance of the obtain catalyst was the best. When the ammonia nitrogen ratio is 1∶1, the denitration efficiency is 88.6%, which is 30% higher than that of self-made hydrothermal TiO2 and 40% higher than that of V-Ti-W catalyst The anti-interference ability is significantly better than that of commercial V-Ti-W catalysts. The mechanism analysis also shows that the oxidation rate of NO plays a key role in the process of photocatalytic denitration, and the presence of ammonia can accelerate the reduction of NO2.
Abstract(26) HTML(26) PDF 3875KB(7)
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: ZnxCd1−xS solid solution photocatalysts with high photocatalytic activity were prepared by the coprecipitation method at room temperature. The optimum process conditions of ZnxCd1−xS photocatalyst for degradation of landfill leachate (LFL) under simulated light, the hydrogen production activity for decomposition of degraded LFL and the Zn atom content, the amount of photocatalyst and illumination time on COD removal efficiency and hydrogen production activity were investigated. Results showed that ZnxCd1−xS exhibits the highest photocatalytic activity when Zn∶Cd = 1∶1. Moreover, when the concentration of Zn0.5Cd0.5S was 1.0 g·L−1, and reaction time was 180 min, the COD removal efficiency of LFL could be up to 30.8% at room temperature. At the same time, Zn0.5Cd0.5S was applied to decompose degraded LFL to produce hydrogen. When the input amount of Zn0.5Cd0.5S was 0.6 g·L−1 and illuminated for 3 h, the maximum hydrogen production is 1533 µmol, and the H2 production rate is 8312 µmol·g−1·h−1. The hydrogen production obtained in this process is much higher than that of photocatalytic decomposition of pure water. After three recycles, the hydrogen production can still remain above 83% of the initial hydrogen production.
Abstract(34) HTML(26) PDF 2043KB(2)
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Amine CO2 capture is an effective post-combustion carbon capture (PCC) technology, while CO2 mineral carbonation is a safe and stable method for CO2 storage. In this paper, these two methods were combined, and the CO2 absorption-mineralization performance of mixed amine solution coupled with CaO under different ratios of mixed amine solution, temperature, reaction time and CaO addition ratio were studied by using MEA/MDEA mixed amine solution as CO2 absorbent and CaO as CO2 mineralizing raw material. The results showed that CaO could effectively mineralize CO2 absorbed in MEA/MDEA solution to realize the regeneration of MEA/MDEA solution simultaneously under normal temperature and pressure. Meanwhile, the MEA/MDEA solution can still maintain a high CO2 conversion rate (77.4%) and CO2 cycle loading (1.03 mol/L) after five cycles of absorption-mineralization experiments. FT-IR and XRD analyses revealed that the addition of CaO provided a large amount of Ca2+ and OH into MEA/MDEA solution, which could react with CO$_3^{2{\rm{ - }}}$/HCO$_3^{\rm{ - }}$ and protonated amine in the solution to form calcium carbonate precipitate and free amine respectively, thus realizing the mineralization of CO2 and the regeneration of MEA/MDEA solution. The main component of solid products obtained was calcium
Abstract(49) HTML(36) PDF 1648KB(2)
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In this work, the effects of O2 and SO2 on gaseous As2O3 adsorption over W-Cu/γ-Al2O3 catalyst were investigated through adsorption experiment and density functional theory (DFT) method. Experimental results show that the As2O3 adsorption is facilitated by O2, and intensified with the increasing concentrations of SO2. However, it is slightly weakened with the SO2 concentration of 2000 ppm. The As2O3 adsorption on W-Cu/γ-Al2O3 surface with adsorbed gas constituents was calculated by DFT simulation to reveal the effect mechanism. The promoting effect of O2 on arsenic adsorption is attributed to the formation of adsorbed oxygen. The pre-adsorbed O atom significantly enhances the adsorption activities of adjacent atoms, and the pre-adsorbed O2 molecule provides the active sites for As2O3 adsorption. When SO2 is introduced, the ${{\rm{SO}}^{2-} _4}$ and ${\rm{HSO}}^-_4$ are formed, which change the potential field of substrate surface, and further enhance the As2O3 adsorption. However, the competitive adsorption between SO2 with As2O3 is strengthened with increasing SO2 concentration, and it is the reason for the decreasing trend of As2O3 adsorption with high concentrations of SO2.
Abstract(50) HTML(46) PDF 4764KB(7)
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Based on the circulating fluidized bed (CFB), Xinjiang Zhundong coal (ZDC) gasification ash (FA: fly ash; BA: bottom slag) was analyzed by industrial analysis, ultimate analysis and Fourier infrared spectroscopy to determine the basic properties and functional group species. The results showed that BA contained up to 99.30% in ash, while FA showed high fixed carbon and C content of 69.3% and 73.78% respectively. Furthermore, the carbonaceous forms and surface morphology of ZDC and FA were characterized by Raman, XRPES and SEM, and the pyrolysis, combustion and gasification characteristics of ZDC and FA were studied with TG-DTG methods. XRPES showed that the C content of the FA surface was 89.42%, and existed primarily as >C−C< and >C−H, while the O was in the form of >C=O. Alkaline earth metals Ca bound to the above-mentioned carbon-involved functional groups caused high disorder in FA. SEM observed that the rough and porous FA surface occurs due to spherical particles of molten mineral attached and embedded surface and pore channels. The thermal conversion characteristics show that the maximum weight loss rate peak temperature of pyrolysis and combustion of FA is significantly higher than that of ZDC, indicating that the pyrolysis and combustion performance of FA is reduced. However, the 100% carbon conversion of FA uses about half the time compared with ZDC and the gasification performance has improved significantly since it has well-developed pore structures, more amorphous carbon and abundant active sites, which enhance the diffusion of CO2 from gasifiers. Briefly, FA has the potential and ability to be recycled for direct utilization in CFB as the gasification feed.
Abstract(36) HTML(22) PDF 809KB(11)
Abstract:
PbCl2 emitted from coal-fired power plants is of great concern due to its extreme toxicity and global migration and accumulation. Unburned carbon is considered as a promising adsorbent for effective PbCl2 removal. However, existing models of unburned carbon do not reflect the structure of carbon defects on the surface of actual unburned carbon. Therefore, it is of great practical importance to develop a defective unburned carbon model. In addition, the carbon model is not deep enough for the adsorption of PbCl2, and the reaction mechanism is not clear. This greatly hinders the development of efficient adsorbents. In order to reveal the adsorption mechanism of PbCl2 on the surface of defective unburned carbon, the adsorption process of PbCl2 on different defective unburned carbon surfaces was systematically investigated by using density functional theory (DFT). The results show that the defective adsorption sites are the best sites for PbCl2 adsorption.
2022, 50(8): 1-8.
Abstract(45) HTML(13) PDF 48771KB(29)
Abstract:
2022, 50(8): 927-936.   doi: 10.1016/S1872-5813(22)60005-7
Abstract(164) HTML(47) PDF 3569KB(38)
Abstract:
A fixed bed reactor and atomic absorption spectroscopy were used to investigate potassium recovery efficiency of Yulin coal loaded with potassium carbonate (ZA-K), Yulin demineralized coal loaded with potassium carbonate (ZA-THK) and synthetic ash (Configurations of four oxides: SiO2, Al2O3, CaO, Fe2O3) loaded with potassium carbonate after reaction. Fourier infrared spectroscopy and Raman spectroscopy were used to study influence of structural evolution of ZA-K and ZA-THK on migration of potassium during pyrolysis. The results show that the yield of water-soluble potassium decreases with increasing temperature. Three times water washing could recover 94.06%−98.80% of the total water-soluble potassium. Formation of insoluble potassium is due to the phase of potassium aluminosilicate formed by potassium, silicon and aluminum in the coal ash. Potassium is easier to volatilize from ZA-THK than that from ZA-K. At 700−850 ℃ potassium in ZA-THK is volatilized 10.28%−44.92% higher than that of ZA-K, resulting from that the ash in ZA-K would fix the loaded potassium in coal ash. Another reason may be caused by decrease in the degree of aromatic polymerization of ZA-THK through demineralization process, leading to more small-ring aromatic structures (2−8 rings) appearing in the coal.
2022, 50(8): 937-953.   doi: 10.1016/S1872-5813(22)60002-1
Abstract(114) HTML(23) PDF 1897KB(33)
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The co-combustion of the low-rank coal with coal derived semi-coke is of great significance to solve the urgent problem of excessively produced semi-coke in China. In this research, the oxy-fuel co-combustion characteristics of Zhundong sub-bituminous coal with bituminous coal derived semi-coke are systematically investigated using thermogravimetric analysis. Compared with air combustion, oxy-fuel atmosphere increased the ignition and burnout temperature by 10 and 40 °C, respectively. Increasing the oxygen concentration to 30% strongly compensated for the slight reduction of the combustion parameters under oxy-fuel condition and much better co-combustion performance was obtained. Three iso-conversional methods, namely, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink, were applied to estimate the activation energy, which can be divided into two stages during the co-combustion process. The average activation energy of sub-bituminous coal, the blend and semi-coke were 49.31, 50.82 and 59.00 kg/mol, respectively. Further, the pre-exponential factor and thermodynamic parameters of the enthalpy change, Gibbs free energy change and entropy change were calculated. Interaction indices were innovatively used for both kinetic-thermodynamic parameters and DTG values. An obvious interaction can be observed during the co-combustion process. The kinetic and thermodynamic results demonstrated that the 30% semi-coke ratio was beneficial to co-combustion. Meanwhile, X-ray fluorescence (XRF) and ash fusion analyses proved that the slagging tendency of sub-bituminous coal ash reduced by blending of semi-coke.
2022, 50(8): 954-965.   doi: 10.1016/S1872-5813(22)60007-0
Abstract(120) HTML(66) PDF 21688KB(48)
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Efficient separation and high-valued utilization of coal gasification ash or slag limit the clean and green development of coal chemical industry. In this paper, a coal-water slurry gasification fine slag (CWSFS) was studied by wet screening and classification. The relationship between the particle composition with different sizes and the structural characteristics was investigated by means of proximate analysis, XRF, XRD, BET and SEM. A classification method of CWSFS was proposed to guide the high-valued utilization of coal gasification slag. Then, dry separation of a coal-water slurry gasification fine slag was carried out using a combined treatment method of crushing and dissociation and airflow classification. The results show that the CWSFS particles of different sizes have obvious differences in fixed carbon content, ash composition and mineral types. For the CWSFS with the particle size above 74 μm, the fixed carbon content is more than 60%, the calorific value is more than 20 MJ/kg, the specific surface area is relatively high and the main component is the residual carbon that contains magnetite and brookite. For the CWSFS with particle sizes between 13−74 μm, the fixed carbon content is between 20%−60%, the calorific value is between 11−19 MJ/kg, the specific surface area is small and the main mineral types are pyroxene, marcasite and hematite, etc. For the CWSFS with a particle size between 0−13 μm, the fixed carbon content is less than 20% and the calorific value is less than 10 MJ/kg, which mainly includes the amorphous glass phase that was rich in aluminum, iron and calcium, quartz and a small amount of fayalite, muscovite and other minerals. According to the fixed carbon content of CWSFS with different particle sizes, the above three components with varying particle size ranges are defined as high-carbon component, medium-carbon component and low-carbon component, respectively. The dry separation test shows that the air flow crushing and classification process can achieve a higher product yield of 29.60% and a high ignition loss of 93.76%, compared to the traditional disc crushing-classification process. Airflow crushing was proved to be able to effectively increase the dissociation degree of residual carbon and greatly improve the separation and enrichment rate of residual carbon.
2022, 50(8): 966-973.   doi: 10.19906/j.cnki.JFCT.2022017
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The pore structure of coal gasification fine slag in Ningxia was characterized and analyzed by low temperature nitrogen adsorption, scanning electron microscope and low field NMR. The pore morphology is mainly fracture shape, and the BET specific surface area of each particle size is large, which is 125.78−589.78 m2/g. The SEM analysis shows that the BJH pore diameter is quite different from the actual situation, and the analysis of pore structure only by low-temperature nitrogen adsorption method has certain limitations. The low field NMR method shows that the products pore sizes of all particle sizes contain micropores, transition pores, mesopores and macropores, and the total porosity is about 27%, mainly mesopores and macropores, followed by micropores and transition pores. The pore structure shows that the products of different particle sizes of coal gasification fine slag have certain adsorption properties, but the medium and large pores are the main storage space of water, resulting in difficulty in dehydration.
2022, 50(8): 974-983.   doi: 10.1016/S1872-5813(22)60001-X
Abstract(131) HTML(48) PDF 46383KB(36)
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The clean and efficient utilization of carbon resources is becoming more and more important, in energy, material, and chemical engineering field, but the mechanism of coke oxidation, especially that of the CO2/CO desorption is not fully studied yet. In this paper, density functional theory was used to study the oxidation mechanism of Zigzag char structure with high coverage of O2, which is related to an oxidation under lower temperature or high pressure. Based on the corresponding quantum chemistry calculation, it is shown that there are several possible pathways for the CO2 desorption process, which may need rearrange to form the structure containing O−C−O clusters. And successively, multiple intermediate reaction steps are required to complete the desorption of CO2. Other than in the literature that the COO–O–C functional group formed first, with then the C–O bond broken and CO2 desorbed respectively, a novel pathway with two C–O bonds broken simultaneously to generate CO2 was found. It results from a functional group of COO–char formed, and certain alternative pathways via C–C bonds breaking were also dealt with, as well as related CO desorptions. The reaction model built was validated by theoretical and experimental results from literature satisfactorily.
2022, 50(8): 984-992.   doi: 10.1016/S1872-5813(22)60004-5
Abstract(81) HTML(38) PDF 14152KB(28)
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The catalytic performance of three LaBO3 perovskites including LaCoO3, LaFeO3 and LaNiO3 in the liquefaction of lignin was investigate through a series of experimental characterization methods such as GC-MS, FT-IR and elemental analysis as well as DFT calculation. The effects of reaction time, temperature, catalyst amount and B cation on the lignin conversion, bio-oil yield and products distribution were considered. The results indicate that all three perovskite catalysts can promote the liquefaction of lignin to produce aromatic compounds; among them, LaCoO3 shows the highest catalytic performance, following by LaNiO3 and LaFeO3. In particular, by using 5% LaCoO3, the bio-oil yield achieves 67.20% after reaction at 180 °C for 60 min, whilst the relative content of mono-aromatic compounds reaches 89.59%. The adsorption of oxygen atoms on the LaBO3 crystal surface conduces to the decrease of bond dissociation energy for lignin (LaCoO3 shows the moderate redox capacity and greatest adsorption energy), whilst the loose and porous morphology can effectively promote the fracture of C−C and CAr−OCH3 of lignin. All these contribute to the macromolecular depolymerization and demethoxylation reaction, producing high value-added compounds such as phenol.
2022, 50(8): 993-1003.   doi: 10.19906/j.cnki.JFCT.2022014
Abstract(110) HTML(26) PDF 4967KB(30)
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Light aromatics are extremely important building blocks in the chemical industry which can be produced from the co-catalytic fast pyrolysis (Co-CFP) of biomass and waste plastics. In this work, torrefaction pretreatment was first employed to remove the oxygen element from bamboo for improving the the quality of bamboo. Then, the hierarchical HZSM-5 was prepared by alkali pretreatment of HZSM-5 using Na2CO3 solution. At last, the optimal operation condition was investigated during Co-CFP of bamboo and high-density polyethylene (HDPE). Results showed that during torrefaction pretreatment process, the carbon content of bamboo gradually increased with the increase of torrefaction temperature, while the oxygen content decreased. The oxygen removal rate and HHV reached their maximum value of 40.3% and 25.64 MJ/kg at 300 ℃, respectively. The specific surface area, pore volume of mesopore, and average pore size of HZSM-5 increased after alkali pretreatment, indicating the development of the micro-mesoporous hierarchical structure in HZSM-5. The Diels-Alder reaction between the furans from pyrolysis of bamboo and the light olefins from pyrolysis of HDPE was the most important synergistic catalytic reaction which could highly promote the formation of light aromatics. The maximum yield of BTX (benzene, toluene, and xylene) was 3.05×108 p.a./mg when the torrefaction temperature, the concentration of Na2CO3, the mass ratio of torrefied bamboo and HDPE, and the pyrolysis temperature were 250 ℃, 0.6 mol/L, 1∶2, and 800 ℃, respectively.
2022, 50(8): 1004-1013.   doi: 10.1016/S1872-5813(22)60015-X
Abstract(126) HTML(90) PDF 15864KB(54)
Abstract:
A series of non-sulfurized K-Ni-Mo-based catalysts with close contact between Ni and K2MoO4 were prepared by hydrothermal reduction for higher alcohol synthesis from syngas. The as-prepared catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR, HR-TEM, SEM-EDS, XPS, H2-TPD, CO-TPD and CO2-TPD techniques. The results indicate that the introduction of K facilitates the formation of the K2MoO4 phase while brings about a decrease of NiMoO4. It can significantly assist the non-dissociative activation of CO for insertion and subsequently alcohol formation. Moreover, the addition of K increases the surface basicity, which leads to more amount of basic hydroxy groups on the catalytic surface. The catalytic basicity ameliorates the production of alcohols. In particular, the K0.4-Ni-Mo catalyst shows the best catalytic behavior with CO conversion of 19.6%, total alcohol selectivity of 57.8% and C2+ alcohol selectivity in the total alcohols of 66.5% at GHSV of 5000 h−1, 240 °C, and 5 MPa.
2022, 50(8): 1014-1022.   doi: 10.1016/S1872-5813(22)60011-2
Abstract(109) HTML(58) PDF 15993KB(27)
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Methyl glycolate (MG) is a high value-added chemical intermediate and widely used in the fields of medicine, chemical industry, fodder and dyes. A series of CuAg/SiO2 catalysts were prepared by sol-gel method for hydrogenation of dimethyl oxalate to MG. The structure of catalysts was characterized by XRD, N2-physical adsorption, FT-IR, TEM, H2-TPR, and XPS, and the influence of Ag loading on catalytic performance was investigated. The 5Ag-Cu/SiO2 catalyst with Ag loading of 5% exhibited the best catalytic performance with DMO conversion of 83.7% and MG selectivity of 72.2%. The characterization results showed that introducing appropriate amount of Ag not only improved the dispersion of copper species, but also increased the content of Cu+, thereby improving the catalytic activity of CuAg/SiO2 catalysts. In addition, the electron transfer between Ag and Cu could effectively stabilize Cu+, and eventually improved the stability of the catalyst.
2016, 44(7): 777-783.
[Abstract](268) [FullText HTML](156) [PDF 2169KB](31)

2016, 44(4): 385-393.
[Abstract](250) [FullText HTML](197) [PDF 1138KB](32)

2016, 44(3): 263-272.
[Abstract](158) [FullText HTML](148) [PDF 1275KB](21)

2016, 44(7): 801-814.
[Abstract](449) [FullText HTML](288) [PDF 8665KB](42)

2016, 44(3): 279-286.
[Abstract](235) [FullText HTML](184) [PDF 12189KB](21)

2016, 44(11): 1388-1393.
[Abstract](235) [FullText HTML](170) [PDF 780KB](22)

2018, 46(2): 179-188.
[Abstract](165) [FullText HTML](93) [PDF 7028KB](21)

2016, 44(9): 1034-1042.
[Abstract](271) [FullText HTML](165) [PDF 809KB](32)

2016, 44(6): 732-737.
[Abstract](215) [FullText HTML](137) [PDF 2776KB](22)

2017, 45(1): 113-122.
[Abstract](243) [FullText HTML](146) [PDF 1085KB](19)

2013, 41(08): 1003-1009.
[Abstract](2169) [PDF 13334KB](30)
Abstract:
A core-shell catalyst CuO-ZnO-Al2O3@Al2O3 for one-step synthesis of dimethyl ether from synthesis gas was prepared using glucose, sucrose or starch as template, and characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The thickness of the Al2O3 shell in the catalyst was altered by controlling the synthesis condition, such as temperature and time. The catalytic performance of dimethyl ether (DME) synthesized from CO hydrogenation on the catalysts were investigated. The conversion of CO and the selectivity of DME on CuO-ZnO-Al2O3@Al2O3 achieved 35.2% and 61.1% at 260 ℃, 5.0 MPa and 1 500 mL/(h·gcat), respectively.
2009, 37(04): 501-505.
[Abstract](1605) [PDF 1335KB](30)
Abstract:
The properties of pyrolysis and combustion for five different sewage sludges are studied by thermal gravimetric analysis at a heating rate of 10℃/min in the atomosphere of nitrogen and oxygen, respectively. The results show that both of the “anaerobic” wastewater treatment and the sludge anaerobic digestion make the organic compounds in sludge so complicated that the organic compounds decomposition and release temperature becomes higher during pyrolyzing, and the “aerobic + anaerobic” process makes the organic compounds in sludge more complicated than the “anaerobic +aerobic” process. There is no influence on the combustion process and the burnout point, but can make the combustion temperature of sludge higher. The thermal reaction mechanisms have been studied with šatava-šesták equation. It shows that the pyrolysis mechanism of these sludges is a process of volatile diffusion at first and then the chemical reaction function, while the combustion mechanism of them is a process of chemical reaction and diffusion function.