Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Abstract(48) HTML(24) PDF 1413KB(5)
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With the rapid development of modern society, the demand for energy is increasing with time. Currently, fossil fuel is still the dominant source of energy in developing countries. The greenhouse effect and environmental problems lead by excessive emission of carbon dioxide causing by the combustion of fossil resources has arouse worldwide concern. Therefore, to achieve carbon emission reduction and carbon neutralization through the capture, storage, conversion and utilization process of carbon dioxide has become the focus of research. Among the utilization of carbon dioxide, the preparation of polymer with carbon dioxide could not only realize the resource utilization of carbon dioxide, but also provide a new approach for the green production of polymer. This paper summarizes the current resource utilization of carbon dioxide in polyurethane, mainly focusing on its physical and chemical applications in materials and introducing its preparation technologies in the process of utilization in detail.
Abstract(47) HTML(11) PDF 1383KB(9)
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The carbonylation reaction of dimethyl ether is an important carbon addition reaction with directed insertion of carbon monoxide into dimethyl ether molecule, which is of great significance in industrial production. In recent years, it has been found that inexpensive mordenite has higher activity and very excellent carbonylation product selectivity for catalyzing the carbonylation reaction of dimethyl ether, hence widely studied. This review has surveyed researches on mordenite catalyzed carbonylation of dimethyl ether, which introduces the mechanism of carbonylation reaction, and summarizes the various methods of controlling the acidic sites inside mordenite and their effects on the carbonylation reaction.
Abstract(20) HTML(6) PDF 2159KB(4)
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In our previous work, high tar yield was achieved by coal pyrolysis coupled with steam reforming of methane (CP-SRM), but the tar has high content of heavy fractions. In order to improve the tar quality by decreasing the heavy tar content and ensuring high tar yield, in-situ catalytic upgrading of tar from the integrated process of coal pyrolysis coupled with steam reforming of methane was conducted over carbon (KD-9) based Ni catalyst. The results showed that at 650 oC, the tar yield of CP-SRM over 5Ni/KD-9 is 24.4%, which is a little lower than that of without catalyst, while the light tar yield (i.e.,18.9%) is 1.4 times higher than that of without catalyst, and the content of C2, C3 and C4 alkyl used as a substitute for benzene significantly increases tar yields by 0.5, 0.6 and 4.0 times, respectively. The content of phenols and naphthalenes in tar also increased dramatically after upgrading. Isotope tracer approach combined with the mass spectra of typical components was employed in exploring the mechanism of the upgrading process. The results showed that 5Ni/KD-9 catalyzes coal tar cracking and SRM at the same time. Small free radicals such as ·CHx, ·H and ·OH generated by SRM can combine with free radicals from tar cracking, thus avoiding excessive cracking of tar.
Abstract(57) HTML(23) PDF 1424KB(2)
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MnOx/ZrO2-Cr2O3 catalysts were prepared by cocurrent coprecipitation and impregnation. The structure and surface properties of the catalyst were characterized by X-ray diffraction (XRD), N2 physical adsorption (BET), hydrogen temperature programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). These results showed that the addition of Cr led to the transformation of ZrO2 crystal form from m-ZrO2 to t-ZrO2. With the increase of Cr content, the BET of the composite oxide ZrO2-Cr2O3 increased gradually, the average pore size decreased and the pore structure also changed. The impregnation of Mn caused the migration of Cr in the ZrO2-Cr2O3 composite oxide, and promoted the transformation of the ZrO2 crystal form from m-ZrO2 to t-ZrO2, the BET and pore structure of the catalyst changed also. The conversion and selectivity of MnOx/ZrO2-Cr2O3 catalysts containing 4% Mn and 2.5% Cr for methyl benzoate hydrogenation were 93.86% and 86.05%, respectively.
Abstract(115) HTML(22) PDF 905KB(33)
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Accompanying with the rapid consumption of fossil fuel resources, a huge amount of CO2 has being released into the atmosphere, which brings serious environmental concerns. However, CO2 can also be considered as a clean and non-toxic carbon resource; the utilization of CO2 by converting it into various hydrocarbons can not only alleviate the greenhouse effect, but also provide a new sustainable route to produce clean fuel and chemical products. In this paper, we attempt to make a review on the recent research progresses in the hydrogenation of CO2 to certain hydrocarbons (including methane, olefins and aromatics) in recent years; in particular, the advance in the development of efficient catalysts for the hydrogenation of CO2 to methane, light olefins and aromatics as well as in the exploration of catalytic reaction mechanisms were retrospectively summarized. Lastly, we would like to have an outlook on the possible trends in the utilization of CO2 as a carbon resource through hydrogenation.
Abstract(53) HTML(32) PDF 1127KB(2)
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By changing the simulation conditions of municipal solid waste incineration experiment (nickel catalyst, water), analysing the reaction temperature, incineration exhaust gas flow, concentration of exhaust gas composition, the dioxin concentrations, the toxicity of dioxin equivalent of absorbing liquid, and the change of the absorption liquid organic matter concentration, the effect of different combustion conditions on dioxins from simulated municipal solid waste incineration was explored. The results showed that the addition of nickel catalyst and water could promote the conversion of macromolecule organic matter to small molecule organic matter during the incineration process, and effectively inhibited the precursor synthesis of dioxins, while the suppression ratio of dioxins were 80.7% and the total equivalent toxicity of dioxins were decreased by 98%.
Abstract(27) HTML(12) PDF 1168KB(5)
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During the coal pyrolysis with the coal ash as heat carrier, the interactions of coal ash and volatile matters could occur in the secondary reactions, which would affect the final sulfur-containing product yields of volatile matter. The objective of this paper was to reveal the effects of coal ash on the sulfur transformation during the secondary reactions. The results showed that the presence of XLT ash during secondary reactions inhibited H2S and COS release at low temperatures due to the sulfur fixation of Fe2O3 existed in the ash. However, it enhanced H2S and COS release at high temperatures, which was mainly caused by the formation of sulfur-containing gases through the reactions between CaSO4 and reducing gas (i.e. H2, CO, and CH4). The influences of Fe2O3 and CaSO4 were also investigated to reveal the mechanism of the influence of coal ash, and it was found that H2S and COS yields were reduced with the addition of Fe2O3, but those two gases were slightly increased by the presence of CaSO4 at 800 ℃, indicating that Fe2O3 and CaSO4 played important roles in the interactions between the coal ash and sulfur-containing gases.
Abstract(34) HTML(10) PDF 918KB(2)
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The batch distillation experiments of bio-oil model compounds were carried out in a pilot rectification column. The distilled fractions of bio-oil model compounds at atmospheric pressure and vacuum distillation were compared by changing the vacuum degree in the system, and the variations of each component in the fractions were analyzed and summarized. The results showed that the total distillate rate of bio-oil model compounds increased and the coking rate decreased, the water was more likely to be evaporated, the initial distillation temperature of organics in the fraction decreased and the distillation rate increased with the decrease of vacuum degree in the system. Therefore, increasing the vacuum degrees can effectively separate the components of the bio-oil model compounds and reduce the energy loss. When the vacuum degree is −0.08 MPa, the distillation effect of the bio-oil model compounds are optimum. The distillation rates of acetic acid and furfural can reach 99.50% and 65.88%, and the distillation rates of phenol and guaiacol both exceed 25%.
Abstract(22) HTML(3) PDF 1054KB(2)
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The oxy-fuel co-combustion and pollutants emission characteristics of coal gangue and semicoke were studied by thermogravimetric analyzer and tube furnace experiments. The effects of semicoke blending ratios, O2 concentration and temperature were investigated. The results show that the combustion performance of blended fuel can be improved with the addition of semicoke and the increases of O2 concentration. The maximum ignition and burnout index are obtained when semicoke blending ratio is 75 %. The CO and SO2 conversion gradually decreases with the increase of semicoke blending ratios. As the increase of temperature, the CO conversion decreases, SO2 conversion increases while NO conversion firstly increases then decreases or slowly grows. The NO emission can be reduced with the addition of semicoke when the temperature is 900°C. However, it will aggravate NO emission at other temperatures. With the increase of O2 concentration, the CO conversion decreases, NO conversion increases while SO2 conversion firstly decreases and then increases. The minimum SO2 conversion is obtained when O2 concentration is 20 %.
Abstract(66) HTML(19) PDF 1037KB(11)
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After the fuel undergoes pyrolysis and combustion in a biomass boiler, the fly ash contains some unburned carbon with abundant pores. However, their low porosities and specific surface areas cannot meet the requirements of the activated carbon for commercial supercapacitors, and the activation method to improve their pore structures is the key to enhance their applicability. After the one-step KOH activation treatment of the unburned carbon with the particle sizes > 0.2 mm, the results showed that the activated carbon has the largest specific area (1982 m2 g−1) at an impregnation ratio of 3.5:1, and the specific capacitance reached 207 F g−1 at the current density of 1 A g−1. The above results indicate that unburned carbon-based activated carbon has a good double layer capacitance performance, providing a reference for the high value-added utilization of biomass fly ash.
Abstract(64) HTML(57) PDF 2197KB(12)
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Furfuryl alcohol is a kind of biomass furan platform compound that cannot be obtained from fossil resources, through which many fine chemicals and fuel additives can be developed. Among them, tetrahydrofurfuryl alcohol (THFA) is a common solvent and an important raw material, and 1,2-pentanediol (1,2-PeD) is an important intermediate for the synthesis of the fungicide propiconazole. In this paper, Ru/solid base catalysts were employed to realize the direct hydrogenolysis of furfuryl alcohol into tetrahydrofurfuryl alcohol and 1,2-pentanediol. Moreover, the catalyst preparation, activation and reaction conditions were screened. It was found that the yield and selectivity of 1, 2-pentanediol were improved by the preparation of Ru based catalyst with basic metal oxides as support. The total yield of tetrahydrofurfuryl alcohol (53%) and 1, 2-pentanediol (32%) was 85% under the optimal reaction conditions over Ru/MnO2. Subsequently, N2 adsorption-desorption, XRD and XPS were employed to reveal the catalytic mechanism which suggested that the synergistic between the surface basic groups and active metals might account for the better catalytic performance.
Abstract(47) HTML(12) PDF 7103KB(3)
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Sorbitol is an important biomass resource, but its fast pyrolysis characteristics and reaction mechanism are not well-studied. In the present study, the fast pyrolysis characteristics of sorbitol were deeply explored and the formation mechanism of the main products was revealed using fast pyrolysis experiments and density functional theory (DFT) calculations. The results show that the fast pyrolysis of sorbitol mainly produces low molecular weight products such as hydroxyacetaldehyde (HAA) and hydroxyacetone (HA), furan-based products such as furfural (FF) and 1-(2-furanyl)-ethanone (2-FE), and anhydrosugar product (isosorbitol (IS)). The yield of HA and HAA products is the highest, due to their lower overall energy barriers. Notably, the generation of HA and HAA are simultaneous. The formation of furan-based products 2-FE and FF needs to overcome relatively higher overall energy barriers, despite that some intermediates also appear in the formation of HA and HAA. Hence, the yields of furan-based products are lower than those of low molecular weight products. The reaction intermediates for formation of anhydrosugar IS are different from those of HA/HAA and 2-FE/FF. The overall energy barrier is high that leads to a very low yield of IS. This study provides a theoretical insight into the mechanism research and technique development for selective pyrolysis of sorbitol.
Abstract(26) HTML(16) PDF 691KB(3)
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β–O–4 is the most abundant linkage in the lignin structure. It is of great significance to convert lignin into monophenols by breaking the β−O−4 linkage. Therefore, β−O−4 dimer model compound is used as raw materials in this paper. The effects of metal catalysts, temperature, time and hydrogen pressure on the conversion of dimer and yield of monophenols were investigated, analyzing by GC-MS, GC-FID, HSQC NMR characterization. The results show that: NaOH and carbon-supported metal catalysts have a synergistic effect, which can enhance the breakage of β−O−4 linkage. The best promotion effect was obtained over Pd/C and NaOH, monomer yield increased from 44.1% to 83.4%. Studies have shown that: NaOH and Pd/C can inhibit the removal of Cα−OH of the dimer and enhance the breakage of β−O−4 linkage effectively, leading to the increment in monomers. And the catalytic system of NaOH and Pd/C have showed excellent performance during the breakage of α−O−4. To the best, alkali lignin was converted into monophenols over NaOH and Pd/C with the yield of 37.5%. The selectivity of benzyl alcohol is as high as 48%.
Abstract(67) HTML(20) PDF 1285KB(12)
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The pyrolysis and gasification characteristics of pelletized cyanobacteria during chemical looping process with red mud oxygen carrier were investigated. The objective is to evaluate influence of red mud oxygen carrier on the pyrolysis and gasification behavior. In a fluidized bed reactor effects of reaction temperature (750−900 ℃) and oxygen carrier to fuel ratio (0.1−0.7) on syngas distribution, carbon conversion and its conversion rate, syngas content and ratio of H2/CO in syngas were investigated. The results indicate that the presence of oxygen carrier has remarkably positive effect on the pyrolysis and gasification processes. It improves pressure gradient caused by devolatilization of the sample. Consequently, the volatiles could be released gradually through the relatively developed channels. During chemical looping gasification H2 content in the syngas has the highest concentration of higher than 45%, followed by CO2, CH4 and CO. The increase of reaction temperature or oxygen carrier to fuel ratio leads to increase in carbon conversion. When reaction temperature increases from 750 to 950 ℃, ratio of H2/CO in the syngas decreases from 7.26 to 4.83. Meanwhile, with increasing oxygen carrier to fuel ratio, ratio of H2/CO first increases and then decreases, and the peak is 5.6 as oxygen carrier to fuel ratio is 0.5.
Abstract(59) HTML(12) PDF 2184KB(8)
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In this work, the impacts of ChCl/carboxylic acids, molar ratios of hydrogen bond acceptors to donors, pretreatment temperature and time on the delignification of poplar were investigated. Characteristic methods including XRD, FT-IR, GPC, and HSQC were used to analyze the solid residue and extracted lignin for the study of the structural evolution of the three components. The results showed that under low temperature of 90 ºC, the delignification of poplar wood was 91% with ChCl/FA pretreatment. About 63% of lignin was collected and the purity of lignin was 90%. Over 98% cellulose remained intact with Iβ type crystal form, and the crystallinity was 70%. The β−O−4 bond content of extracted lignin was 84.8% (71% of the original β−O−4 bond), and M n of the lignin was 1400 g/mol, suggesting the extracted lignin to be an ideal raw material for monophenlics production.
Abstract(108) HTML(80) PDF 1220KB(23)
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In recent years, the conversion of biomass-derived platform compounds into a variety of high value fuel and chemical products has attracted increasing attention from researchers. 5-Hydroxymethylfurfural (HMF) and furfural (FFR) belong to a class of important biomass-derived platform chemicals. The molecular structure of HMF and FFR is consisted of aldehyde group, furan ring and other functional groups, which endow them with unique chemical properties. In this paper, the research advances on the catalytic hydrogenation of HMF and FFR in various hydrogen sources, such as hydrogen, alcohol, silanes and formic acid, have been reviewed in detail. In addition, the main influencing factors like catalyst type and reaction conditions on the hydrogenation process as well as the reaction mechanism are discussed in depth. Meanwhile, research foreground in the catalytic hydrogenation of HMF/FFR has been prospected.
Abstract(125) HTML(16) PDF 1108KB(20)
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Pyrolysis technology has a great application prospect in the future. The essential properties of cellulose, pyrolysis mechanism, research tools, catalyst type and other important factors affecting the products distribution are discussed in detail. Particularly, the addition of a variety of catalysts and the optimum design of reaction device can significantly accelerate the cellulose pyrolysis, improve the product distribution and increase the selectivity of some high-value chemicals, thus effectively enhancing the resource and energy utilization value of pyrolysis products. Last but not the least, the future research orientation of cellulose pyrolysis technology is put forward based on some key questions to be solved.
Abstract(36) HTML(21) PDF 8528KB(7)
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The selective oxidation of primary alcohols represents a premier route for the synthesis of aldehydes as intermediates of multiple commercial fine chemicals such as drugs and perfumes. In particular, catalytically selective oxidation of primary alcohol in use of oxygen is of great interest, owning to its high efficiency, solvent-free, and easy separation. As such, choosing this route to pursue desired atomic economy has been an essential topic of common concern in both academic and industrial circles in recent years. Boron nitride with graphite like structure is a new catalyst developed in recent years, which has the characteristics of stability and good thermal conductivity. In this contribution, three kinds of boron nitride (BN) with different structural characteristics were used as carriers to support Au nano metal for selective oxidation of benzyl alcohol. It was found that the crystallinity and specific surface area of the carriers had a great influence on the size of active phase Au. The specific surface area of ​​Au/BN500 is four times higher than that of the Au/BN600 and Au/BN700. Compared with Au/BN700, Au/BN500 catalyst has better dispersion and smaller particle size (13 vs. 3.2 nm). And the catalytic activity of Au/BN500 is about as twice much as that of the other two, except the activity loss by ca. 30% within 5 hours. The results in this paper provide enriched experimental and theoretical references for rational design and development of novel high-performance boron nitride-based oxidative dehydrogenation catalysts.
Abstract(61) HTML(14) PDF 1854KB(3)
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Xylose is the predominant component of hemicellulose, and converting xylose to valuable compounds is essential to achieve biomass utilization. Herein, N-doped carbon nanotubes encapsulated metal catalysts (Co@NC) with hydrogenation and isomerization capacities were synthesized via bottom-up method for catalyzing xylose hydrogenolysis into 1,2-diols. The physicochemical properties of Co@NC prepared with different calcination temperature were determined by XRD, TEM, XPS and so on. The Co@NC prepared at 600 oC exhibited the optimal catalytic activity, and the yield of diols reached 70.1% with ethylene glycol, 1,2-propylene glycol and 1,2-pentanediol being 17.6%, 25.1% and 27.4%, respectively. The doping N species served as the basic sites which benefited the isomerization of xylose to xylulose. Xylulose was subsequently converted to glycolaldehyde and acetol through Retro-aldol reaction, followed by hydrogenation to produce ethylene glycol and 1,2-propylene glycol. 1,2-Pentanediol derived from the selective hydrodeoxygenation of xylose, the yield of which surpassed the results that had been reported. The Co@NC catalysts with high robustness under harsh hydrothermal conditions provided new insights into the effective conversion of lignocellulosic biomass to 1,2-diols.
Abstract(67) HTML(24) PDF 1202KB(13)
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In order to reduce N-/O-compounds content and improve the quality of microalgae bio-oil, the co-pyrolysis /catalytic of Nannochloropsis sp. (NS) and polyethylene (LDPE) were studied in a fixed bed, and discussed the distribution of N and O, as well as the interaction between microalgae and LDPE and the influence of the addition of catalyst. It is found that co-pyrolysis could effectively inhibit the transformation of O and N to oil, promote O releasing as H2O and N conversion to gas products. In addition, plastic adding significantly reduced the content of O-/N-compounds in oil, such as carboxylic acid, amide and N-heterocyclic, and increased the aliphatics content. Besides, it effectively promoted the formation of hydrocarbon gas, and showed a certain synergistic effect on CO and H2, and the interaction reached the maximum at 25%LDPE. Furthermore, ZSM-5 could promote the formation of hydrocarbon gas, increase the LHV of gas products (35.6 MJ/Nm3), and further reduce the nitrogen compounds in the oil, while the N in microalgae transferred to gas, and O converted to gas and H2O, which resulted in the further reduction of the O and N contents in the oil. Moreover, catalytic co–pyrolysis could inhibit the formation of aromatic hydrocarbons to a certain extent and improve the selectivity of aliphatic hydrocarbons.
Abstract(39) HTML(7) PDF 1621KB(11)
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Catalytic cracking of triglycerides and their derivatives (e.g., fatty acid methyl esters, FAMEs) by HZSM-5 zeolite offers a promising route to produce renewable aromatics and olefins, but it is primarily hindered by the rapid catalyst deactivation caused by coke. In this work, the co-cracking of FAMEs and methanol over HZSM-5/Al2O3 composites was developed to regulate the product distribution and slower the catalyst deactivation. Co-feeding methanol with FAMEs enhanced the olefin selectivity at the expense of aromatics, and the total selectivities of aromatics and olefins added up to 70.9% with an optimized methanol content of 60%. The co-feeding of methanol not only promoted the olefin yield but also retarded the consecutive H-elimination of aromatics to polycyclic aromatics, thus reducing the coke formation and prolonging the catalyst lifespan. Under the conditions of 450 °C, 0.16 MPa and a space velocity of FAMEs at 4 h−1, increasing the methanol blending ratio in FAMEs from zero to 50% reduced coke from 17.8% to 10.1% after reaction for 12 h. Besides, the spent catalyst for the co-cracking reaction could be easily regenerated by coke combustion, yielding similar structure, acidity and activity to those of the fresh one.
Abstract(18) HTML(5) PDF 1197KB(2)
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Catalytic lignin depolymerization (CCLD) for liquid fuels and phenolic monomers was investigated over various supports including clays (e.g., sepiolite (SEP), attapulgite (ATP), and montmorillonite (MTM)), and oxides (e.g., Al2O3 and SiO2) as well as their supported Mo-based catalysts under supercritical ethanol. The characterization results demonstrated that different supports with diverse structural properties could affect the textural structures, surface Mo5+ content, and acid sites distribution. Clay-based supports had more strong acid sites as compared with Al2O3 and SiO2, which went against the production of lignin oil (LO) and led to form more solid products during CLD experiments. Meanwhile, the obtained petroleum ether-soluble product (PEsp) in LO catalyzed by sole supports was mainly alkyl/alkoxy substituted phenols. Additionally, Mo species (especially Mo5+) significantly increased the yields of LO and PEsp. Mo/SiO2 had the highest surface Mo5+ species, showing the highest LO yield of 85.2%, in which the produced alkyl/alkoxy substituted phenols reached 450.3 mg/glignin. Among the clay-supported Mo catalysts, Mo/SEP presented superior LO (82.3%) and PEsp (70.8%) yields and the generated substituted phenols reached 398.8 mg/glignin. This paper systematically reported the application of green and environmentally friendly clay-based materials in lignin conversion, which provides some key information for the development of clay catalysts for biomass conversion.
Abstract(158) HTML(26) PDF 1104KB(51)
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The goal of “carbon peak and carbon neutrality” provides a powerful engine for the transformation of energy structure in China. As response to the sustainable development and energy structure transformation, the development of biomass high-density fuels is necessary, which can provide renewable alternatives for traditional petroleum-based high-density fuels. Herein, the properties and applications of typical petroleum-based high-density fuels including RJ-4 and JP-10 are reviewed. We also introduce the routes for synthesizing RJ-4, JP-10 and other polycyclic fuels from terpenoids and lignocellulose platform compounds, showing the feasibility of converting biomass to high-density fuels. Finally, we emphasize the current bottlenecks and development trends in the synthesis and application of biomass high-density fuels.
Abstract(31) HTML(12) PDF 869KB(2)
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Lemon peel, as a typical carbon solid waste in fruit processing industry, of which efficient recycling and resource utilization contribute to the development of renewable liquid fuel and economic benefits. Citric acid contained in lemon peel has been proved to be a weak acid that can effectively promote the hydrothermal conversion of biomass and its derivatives to produce high value-added furan products. Therefore, sulfuric acid is used to catalyze the hydrolysis of lemon peel to produce precursor of important liquid fuel, such as levulinic acid (LA) and furfural (FF). The promotion effect of common metal salt on catalysis of sulfuric acid to the hydrolysis process of lemon peel is explored. The citric acid contained in lemon peel promotes the hydrolysis process. Combined with catalysis of sulfuric acid, the LA yield as 22.6% can be obtained under the mild hydrolysis conditions of 170 ℃ and 90 min, and the addition of the KCl can effectively inhibit the secondary reaction of the hydrolysis process of the lemon peel and enhance the interaction of the sulfuric acid and the lemon peel. Compared with AlCl3 and FeCl3, the LA yield is increased to 27.9% by the addition of KCl. Preparing conditions of glucose and FF are milder than that of LA. Enhancement of temperature and acidic concentration, and prolonging reaction time all lead to significant decrease in glucose and FF yield.
Abstract(55) HTML(18) PDF 2059KB(10)
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Ru/HZSM-5 was prepared and used to upgrade bio-oil online and the changes of bio-oil yield and physicochemical properties were analyzed through the total quality index ( TQI ). The changes of the chemical compositions of the bio-oils were compared; simultaneously, the coking situation of the catalyst was characterized. The results showed that the yield and physicochemical properties of bio-oil obtained by using fresh catalyst were high, and the TQI increased from 0.15 to 6.45; with the increase of using times, the TQI first increased slightly to 6.68, then decreased rapidly to 1.25, and reduced to only 0.27 after the fourth usage. In the initial stage, a small amount of coking reactions made the strong acid sites partially passivated, which improved the aromatization performance. When the catalyst was used twice, the relative content of hydrocarbons in the bio-oil reached 53.79%, of which the relative content of light aliphatic hydrocarbons was 16.87%, and the relative content of monocyclic aromatic hydrocarbons was 32.65%. After the fourth usage, the relative content of hydrocarbons in the bio-oil was only 9.32%, and the catalyst layer basically lost the upgrading effect, and had adverse effects on pyrolysis vapors such as secondary cracking or polymerization. Before the third usage, the low-temperature pyrolytic coke attached to the catalyst surface was dominant. After the third usage, the low-temperature pyrolytic coke and high-temperature catalytic coke increased significantly, and the catalyst activity decreased sharply. Continuous usage of catalyst slightly increased coke, of which the pyrolytic coke increased mainly.
Abstract(27) HTML(16) PDF 1691KB(1)
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To investigate the catalytic properties of β zeolite for catalytic alkylation of C9 aromatics with propylene, β zeolites modified with phosphorus were prepared by using impregnation method. The modified β catalysts with different loading amount of phosphorus were characterized by XRD, SEM, EDX, MAS NMR, Py-IR, N2 adsorption-desorption, and NH3-TPD. The results showed that the morphology and crystal structure of the β zeolite catalysts did not change obviously after modification with phosphorus. However, the specific surface area and the surface Si/Al mass ratio of the β zeolite decreased with the increase of amount of phosphorus. It was proved that the interaction between the phosphorus and β zeolite would affect the acid strength distribution of β zeolite and the catalytic performance of alkylation of C9 aromatics. In comparison with β zeolite, the β zeolite modified with 0.5 wt.% phosphorus (β-0.5P) has good catalytic performance in alkylation reaction of C9 aromatics. The ratio of ${\rm{C}}_{12}^+$ aromatics in the alkylation products was up to 17%, and the value of m1,3,5-TMB/mC9 was increased by 5.3%. The β-0.5P catalytic activity showed stable after reaction for 10 h. However, when the loading amount of phosphorus on β zeolite was too high, the alkylation activity of the catalyst decreased and the isomerization and disproportionation performance of the catalyst increased.
Abstract(42) HTML(21) PDF 1529KB(5)
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With coal gangue (CG) as the carbon-containing carrier, starch as supplementary C source and nickel nitrate as Ni source, Ni/C/CG composite microwave absorbing materials were prepared by a solution impregnation and then a carbothermal reduction process. The influence of the carbothermal reduction temperature on the composition, microstructure and performance of materials was carefully studied. It was found that, the carbothermal reduction temperature had a great effect on the crystalline state of carbon and Ni, as well as the size of Ni particles, further greatly affected the electromagnetic properties, especially the dielectric properties of the materials. Due to the combination of good impedance match and strong microwave attenuation ability, the Ni/C/CG composites prepared under a wide temperature range of 600−800 ℃ all displayed excellent microwave absorption performance. For the sample heat-treated at 800 ℃, the minimum reflection loss could reach −20.9 dB at 12.9 GHz and the corresponding effective absorption band was 3.7 GHz with a coating thickness of only 2 mm. In addition, the dielectric loss was the dominant microwave absorption mechanism, which mainly originated from the conductive loss caused by the graphite carbon and Ni particles, and the interfacial polarization loss due to the existence of interface between Ni, C and CG.
Abstract(60) HTML(25) PDF 2569KB(3)
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In order to obtain the NO formation mechanism during the coal combustion, the heterogeneous oxidation of nitrogen-containing char by CO2 were investigated based on density functional theory. Simplified char models containing pyrrole nitrogen or pyridine nitrogen were selected as the carbonaceous surfaces. Geometric optimizations were carried out at the B3LYP–D3/6–31G(d) level. Energies of optimized geometries were calculated at the B3LYP–D3/def2–TZVP level. The results show that CO2 oxidation of nitrogen-containing char is composed of three stages: namely CO2 adsorption, CO desorption and NO desorption. In the reaction of CO2 heterogeneous oxidation of pyrrole nitrogen-containing char, CO2 molecules tend to absorb in the C−O−down mode (C−C bonding, N−O bonding) to form a five-membered heterocyclic structure containing nitrogen and oxygen atoms. Then, the surface carbonyl groups and N(O) could form when the C−O bonds of the original CO2 molecules in the five-membered ring broken, and the CO and NO are desorbed, respectively. The reaction is 401.2 kJ/mol endothermic, and the highest energy barrier is 197.6 kJ/mol. In the reaction of CO2 heterogeneous oxidation of pyridine nitrogen-containing char, CO2 molecules tend to form six-membered heterocyclic ring containing nitrogen and oxygen atoms after adsorption in the C−O−down and C−C bonding and C−O bonding mode. And then CO and NO molecules are desorbed. The reaction is 598.6 kJ/mol endothermic, and the energy barrier of rate–determining step is 292.0 kJ/mol.
Abstract(18) HTML(8) PDF 1460KB(2)
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Versatile and environmentally benign dimethyl carbonate (DMC) synthesized by propylene carbonate (PC) and methanol via transesterification is green and energy efficient. A series of solid base catalysts derived from F-Ca-Mg-Al layered double hydroxides (LDHs) with different NaF amount were prepared, characterized and tested for the transesterification reaction. The properties of the catalysts modified by fluorine have improved obviously. The catalytic activity increases in the order of: FCMA-0.8 > FCMA-0.4 > FCMA-1.2 > FCMA-1.6 > FCMA-0, which is consistent with the total basic sites amount and the strong basic sites amount. FCMA-0.8 has the best catalytic activity as pure CaO catalyst, and the PC conversion, DMC selectivity and DMC yield are 66.8%, 97.4% and 65.1%, respectively. Furthermore, the DMC yield for FCMA-0.8 just decreased 3.9% (33.2% for CaO catalyst) after 10 recycles. FCMA-0.8 has good prospects in the transesterification of PC with methanol to DMC for industrial application.
Abstract(92) HTML(26) PDF 1053KB(5)
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Acetic acid, phenol, guaiacol and 4-methylguaiacol in bio-oil aqueous fraction were extracted and separated experimentally with the choice of hydrophobic ionic liquid [Bmim][NTf2] as extractant. The effects of extraction time and extractant dosage on the extraction efficiency were explored. With the help of density functional theory (DFT) calculations, the interaction mechanism between [Bmim][NTf2] and phenol was also clarified. The results showed that under the optimal extraction condition (mIL/mW = 0.4, extraction time = 5 min), the extraction efficiencies of acetic acid, phenol, guaiacol and 4-methylguaiacol in the aqueous fraction were 2.71%, 95.41%, 92.04%, and 97.98%, respectively. It was indicated that [Bmim][NTf2] had better selectivity and superior extraction efficiency for phenols in bio-oil aqueous fraction. The results of DFT calculation demonstrated that the strong hydrogen bonding interaction as well as weak vdW interaction between [Bmim][NTf2] and phenols played an important role in extraction and dephenolization of bio-oil aqueous fraction. The phenols in [Bmim][NTf2] can be effectively removed by alkali washing treatment to achieve recovery of [Bmim][NTf2] and next high efficiency extraction.
Abstract(77) HTML(8) PDF 1042KB(18)
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Deposition or slagging problem caused by the alkali metal species is one of the major obstacles to utilize biomass fuel in combustion and gasification plant. The paper mainly studies the effect of water leaching on alkali-induced slagging properties of corn straw and rice straw. The original mineral form of alkali elements in biomass straw was studied with comparison of low temperature ash of biomass before and after water leaching. The release and transformation of alkali compounds in biomass straw at different temperatures during heating were analyzed with combination of the XRD result of the heated biomass and the chemical composition of the digested samples. The result shows that the potassium in corn and rice straw mainly exists in the form of KNO3, KClO4, K2SO4 and KAlSi3O8, in which KNO3, K2SO4 and KClO4 is mostly removed in water leaching. The fusion temperatures increased after water leaching, especially for rice straw ash, which is a typical sample that the basic compounds are mainly potassium-containing compounds. The decrease of potassium content with temperature in the original corn and rice was because the potassium-containing minerals decomposed and escaped at 25−1000 °C. The release of potassium in the range of 400−800 °C significantly reduced for corn and rice straw after water leaching, but the potassium content will still decrease above 800 °C. The decrease of magnesium content in corn with increasing temperature may be due to the volatilization of magnesium oxide under the action of carbon reduction. For fuels with high alkali metal content after water leaching, the residual alkali metal will still escape and cause deposition or slagging in the furnace, especially in the temperature range above 800 °C.
Abstract(39) HTML(30) PDF 1830KB(5)
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Torrefaction atmosphere is one of the key problems in industrial application of torrefaction technology. In this paper, the effects of oxygen concentration and torrefaction temperature on the physicochemical properties of rice straw during oxidative torrefaction were investigated by simulating the atmosphere of oxy-fuel combustion flue gas. The results show that the effect of temperature on oxidative torrefaction is more significant compared with oxygen concentration. At low temperature (< 250 ℃), oxygen concentration has little effect on the mass and energy yield of torrefied rice straw, but it has obvious effect at high temperature (> 250 ℃). With an increase of temperature (> 250 ℃), the mass and energy yield of torrefied rice straw decreased significantly. When the temperature and oxygen concentration are 250 ℃ and 6%, respectively, it is a suitable oxidative torrefaction condition. Under this condition, the mass and energy yield of torrefied rice straw can be maintained above 70% and 80%, respectively. Increasing the temperature mainly enhances the torrefaction reaction, and the oxidation reaction has an obvious effect when the oxygen concentration exceeds 6%. The retention ratio of chlorine and potassium showed an downward trend with the increase of temperature and oxygen concentration, but the effect of increasing temperature was more significant.
Abstract(115) HTML(35) PDF 820KB(7)
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With the booming of biodiesel industry, it is urgent to high-valued to recycle glycerol as the main by-product. The condensation of glycerol (GLY) with acetone to produce acetone glycidol (2, 2-dimethyl-1, 3-dioxolane-4-methanol, Solketal) is promising direction for GLY utilization, because Solketal can function as fuel additive to modify the fuel viscosity and low-temperature performance of oil significantly, due to the function of Solketal as fuel additive to modify the fuel viscosity and low-temperature performance of oil significantly, and reducing the emission of carbon monoxide, small solid particles and other environmentally unfriendly substances further. However, the reaction needs to be accelerated by the catalyst with acid nature, thus the design and modification over the structure and acid properties of catalysts are dominating the process of glycerol ketonization reaction. So, this paper systematically reviews the progress of homogeneous and heterogeneous acid catalysts in this reaction and the reaction mechanism, taking into account the relevant literature in recent years. It is first classified based on the perspective of structural properties, followed by representations in advantages and characteristics of different catalysts, and highlighted in terms of the influence of their structural properties on catalytic activity. Finally, some future directions for this research field are pointed out.
Abstract(50) HTML(20) PDF 764KB(6)
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The process of directional alcoholysis of cellulose and hemicellulose in bamboo was investigated using solid acid as catalyst and dialkoxymethane/lower alcohol as co-solvent. By adjusting the reaction conditions (composition and ratio of the co-solvent, the type and amount of solid acid catalyst, reaction temperature and time), the optimal reaction conditions are obtained (dimethoxymethane/methanol with a mass ratio of 5 g/15 g, the solid acid catalyst silicotungstic acid 0.002 mol, reaction time 120 min, and reaction temperature 200 ℃), the conversion of bamboo was 81.53 wt%, and the yield of methyl levulinate was 28.39 wt%. At the same time, the conversion process of a variety of biomass model compounds (xylose, glucose, furfural, 5-hydroxymethyl furfural, pentosan and microcrystalline cellulose) was studied in detail, then the fundamental mechanism of directional alcoholysis conversion of cellulose and hemicellulose to produce methyl levulinate was put forward according to the detection results of intermediate products in the reaction process.
Abstract(79) HTML(30) PDF 628KB(15)
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Direct, nonoxidative conversion of methane towards olefins/aromatics is a hot topic in the background of “carbon peak, carbon neutrality”, owing to zero CO2 emissions, high carbon atom utilization efficiency and hydrogen production. In the present paper, the advances of methane dehydroaromatization (MDA) and direct nonoxidative conversion of methane to olefins, aromatics, and hydrogen (MTOAH) are reviewed, based on our research works and the publications from 2018 to 2021. The determination of active sites, reaction intermediates, reaction mechanism, catalyst modification and improvement were considered. Finally, the future prospect was given for the direct nonoxidative conversion of methane to olefins/aromatics.
Abstract(46) HTML(11) PDF 977KB(8)
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Synthesis of low-cost, high-activity and high-stability Pt-based catalysts is of great importance to the large commercialization of proton exchange membrane fuel cell (PEMFC). Doping non-precious metals such as cobalt (Co) with Pt is attractive due to the reduced depletion of Pt and, more importantly, the enhanced activity on the oxygen reduction reaction (ORR) compared with pure Pt. In this work, carbon-supported platinum-cobalt nanoparticles(NPs) were prepared by the impregnation reduction method for the ORR catalyst. By changing the heat treatment temperature, the structure, the crystal phase and the size of the Pt3Co nanoparticles could be controlled. TEM and XRD characterizations show that larger size NPs with higher alloying degree are obtained at higher temperature. The electrochemical results demonstrate that the Pt3Co NPs at 800 ℃ have the highest mass activity (0.41 A/mgPt) and the best stability among all the samples due to their lower particle size and higher alloying degree. Further Density functional theory(DFT) calculation shows that the surface of the Pt3Co structure with high alloying degree can reduce the rate-determining step barrier and improve the ORR activity.
Abstract(44) HTML(14) PDF 1245KB(6)
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A series of iron sulfide catalysts were prepared in 5% H2S/H2 atmosphere at different pre-sulfidation temperature, and their catalytic activity for naphthalene hydrogenation was studied at 360°C in 1% H2S/H2 atmosphere of 5MPa. Assisted with MES, XRD and XPS, the component transformation of the catalyst under varied pre-sulfidation temperature and reaction conditions was researched. Data showed that the sulfidation process was of sulfurizing from surface to interior in the order of FeS2→FeS、Fe1–xS→Fe3S4→Fe2O3, during which the rise of temperature benefited sulfur transferring to the body phase; after contacting 1% H2S/H2 gas, particles rapidly transformed to Fe1–xS from outside to inside. By adjusting sulfidation conditions, the content of Fe1–xS was high while the particle size was small, making it possible to obtain the highest activity of the catalyst.
Abstract(46) HTML(35) PDF 5219KB(2)
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The morphological structure of six samples including the rapid pyrolysis soot of solid fuels (coal, biomass), the soot from non-catalytic partial oxidation(NC-POX) of natural gas in a laboratory pilot plant and an industrial plant, the commercial carbon black in natural gas furnace /coal tar furnace, were characterized by using a high-resolution transmission electron microscope. Based on atmospheric thermogravimetric analyzer, the non-isothermal method (50 °C−800 °C) was adopted to study the ignition point and the oxidation reaction rate of soot, and the oxidation reaction kinetic parameters of soot was obtained. Studies showed that the physical and chemical properties of varied soot were quite different. The soot from the rapid pyrolysis of coal and biomass presented a higher sphericity and a larger particle size. The soot from NC-POX of natural gas in a laboratory pilot plant was formed at a lower temperature which caused the particle being wrapped by a carbon capsule. The soot from NC-POX of natural gas in an industrial plant had a hollow structure and a small particle size. The reactivity of the soot from NC-POX of natural gas in a laboratory pilot plant is close to that of the industrial plant, which is 3.1 times that of the commercial natural gas furnace carbon black and 3.2 times that of the commercial coal tar furnace carbon black; the reactivity of NC-POX soot is 9.0 times of the rapid pyrolysis soot of coal, and 26.6 times of the rapid pyrolysis soot of biomass. The activation energy of 2 kinds of NC-POX soot and 2 kinds of commercial carbon blacks present staged forms with increasing temperature. The activation energy of the 2 rapid pyrolysis soot was basically unchanged with increasing the temperature.
Abstract(50) HTML(19) PDF 1312KB(9)
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In this paper, two kinds of coal (Baiyinhua lignite and coal from Ezhou Power Plant) were selected to study the occurrence of heavy metal arsenic, selenium, and lead in coal and their release during the ashing process; combined with the changes of minerals in coal, the influence of ashing conditions on mineral conversion were also studied. The burn-out temperature of the coal was determined from the thermal weight loss curve by extrapolation method, and then the coal sample was ashed separately in combination with the national standard method. The obtained ash samples were characterized by XRD, XRF, and TG-DTG to analyze the change characteristics of coal minerals at different ashing temperatures. The content and occurrence of arsenic, selenium, and lead in coal samples were extracted by sequential chemical extraction method. The heavy metals in the ash sample were extracted by HNO3 + HF, and the heavy metal content in the extract was detected by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The results show that the heavy metals in BYH coal are mainly As in the form of sulfide bound state, making the volatility of arsenic increase with temperature easily; the heavy metals in EZ are mainly sulfide-bound Pb, which is also easy to varies with temperature; selenium in coal mainly exists in the form of organic binding state and sulfide binding state. The main mineral changes occuring during coal ashing are that kaolin is gradually dehydroxylated into metakaolin and finally converted into mullite; pyrite is oxidized to form hematite; gypsum is dehydrated to form anhydrite. The release rate of heavy metals during coal ashing is affected by the content and occurrence of heavy metals in coal and the temperature. The release rate of each heavy metal is greatly affected by the combustion temperature in the ashing process. The higher the content of the sulfide bound state, the larger the release rate increases with the temperature.
Abstract(47) HTML(8) PDF 1101KB(2)
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TiO2 nanobelts were prepared by hydrothermal synthesis and acid treatment, then calcination at different temperatures. And subsequently Pt nanoparticles were deposited on the TiO2 nanobelts. Pt/TiO2 catalytic properties were investigated in the oxidation of formaldehyde. These catalysts were characterized by various techniques and the characterization results showed that the applied thermal treatment temperature greatly influenced the phase composition and surface structure of TiO2 nanobelts, as well as the number of oxygen vacancies and hydroxyl groups on the surface. The Pt/TiO2 nanobelts thermally treated at 600 °C had more oxygen vacancies, which were conducive to the activation of adsorbed oxygen, formed more Ti-(OH)x-Pt species, and showed higher catalytic activity. At 25 °C and relative humidity of 55%, the conversion of formaldehyde reach 91.6%.
Abstract(101) HTML(21) PDF 1675KB(13)
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The size distribution of aromatic nuclei in coal influences the composition of tar and char during pyrolysis. Pyrolytic experiments of Naomaohu (NMH) coal from Xinjiang in China were carried out in a fixed-bed reactor at different temperatures to study the size distribution of aromatic nuclei during coal pyrolysis. With the increase of pyrolysis temperature, the aromaticity of char, the graphitization degree, and the order degree of aromatic layers increase. The tar is mainly composed of aromatic clusters with 1−2 rings and contains a small amount of aromatic clusters with 3 or more rings. The tar yield increases first and then decreases with increasing temperature (maximum at 550 ℃). However, the changes in the Synchronous fluorescence spectra of the tars with increasing temperature are not significant, indicating that the size distribution of aromatic nuclei in tar changes little with no significant condensation polymerization, and also indicating that the number of bridged bonds and the cracking activity distribution of these bridge chains in different size aromatic rings are relatively uniform. With the increase of pyrolysis temperature, the content of 1 × 1 aromatic layers in the pyrolysis products (char and tar) decreases gradually. When the pyrolysis temperature is at between 500 and 600 ℃, the 1 × 1 aromatic layers are mainly transformed into 2 × 2 and 3 × 3 aromatic layers. When the temperature is higher than 650 ℃, the formation of aromatic layers with the size of 4 × 4 and above takes the main part of condensation polymerization.
Abstract(73) HTML(24) PDF 3318KB(11)
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Alkylbenzenes are important bulky chemicals. The production of alkylbenzenes through benzene and syngas alkylation technology of coal chemical industry can reduce the domestic dependence on petroleum. In this study, mechanical mixture of ZnAlOx and ZSM-5 were used to catalyze the alkylation reaction of benzene and syngas. The results showed that the best performance catalyst was obtained with the 1∶1 mass ratio of the two components and the 2∶1 molar ratio of zinc to aluminum. It was suggested that the main reaction intermediates of methanol and dimethyl are produced on the O vacancy of ZnO and L acidic center of Al2O3 in ZnAlOx. And the alkylated benzenes are formed by the reaction of benzene with the intermediates over ZSM-5. Due to the high temperature property of ZnAlOx for methanol synthesis which can accommodate to the reaction of ZSM-5 for benzene alkylation, the high catalytic activity and selectivity was obtained.
Abstract(57) HTML(22) PDF 1161KB(9)
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Using TPAOH as the template, TEOS as the silicon source and TBOT as the titanium source, the as-prepared samples utilizing a dynamic crystallizating kettle have possessed regular morphology and the average particle size of 600 nm. By modulating the dosage of TBOT, and then changing the molar ratio of titanium to silicon in the initial synthesis solution, the effect of silicon to titanium ratio on TS-1 molecular sieve has been investigated. TS-1 zeolite properties were characterized by means of SEM, TEM, XRD, FT-IR, UV-vis, XPS, N2 adsorption and desorption technology. Finally, using a simulated system of thiophene n-octane dissolved in octane, the catalytic oxidative desulfurization performance of TS-1 zeolite has been investigated.
Abstract(70) HTML(19) PDF 1383KB(11)
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Previous works demonstrated that the Fe-Ag/Al2O3 catalyst could efficiently reduce NO into N2 by propene with a good resistance towards H2O and SO2. In this work, the effect of preparation method on the performance of Fe-Ag/Al2O3 catalyst in the selective catalytic reduction (SCR) of NO with propene was investigated. Three typical methods, viz., physical grinding (PG), direct impregnation (DI) and sol-gel-impregnation (SGI), were comparatively used to load the active components on the supports. The results indicate that all the catalysts prepared by these three methods display good tolerance towards water vapor and SO2. However, they are rather different in the denitration efficiency; the maximum NO removal efficiency of the catalysts prepared by three methods follows the order of SGI (100%) > PG (62%) > DI (58%). Various characterization results reveal that the catalytic performance of Fe-Ag/Al2O3/CM was mainly related to the porous surface and Fe–Ag interaction. By using the SGI approach, the primary support of cordierite and the secondary support of Al2O3 work together to achieve a large surface area and an intense interaction between Fe and Ag on the resultant DP-Fe/Ag/Al2O3/CM catalyst, forming the bimetal AgFeO2 oxide and displaying the best reducibility. In terms of the PG method, the prepared GR-Fe/Ag/Al2O3 catalyst is powdery and shows the largest surface area; however, without cordierite serving as the monolithic support, Ag2O and Fe3O4 exist as separate oxides together with a hint of elemental Ag. As a result, the GR-Fe/Ag/Al2O3 catalyst shows poor reducibility due to the lack of porous surface to facilitate the Fe–Ag interaction. In contrast, the DP-Fe/Ag/CM catalyst prepared using the DI method shows rather poor dispersion of Fe and Ag due to the absence of the secondary support of Al2O3; in fact, individual Ag2O and Fe3O4 agglomerate on the catalyst surface and no AgFeO2 species is detected. Therefore, the DP-Fe/Ag/CM catalyst, with the surface area of only 1/4 of that for Fe-Ag/Al2O3/CM-SGI, exhibits the poorest activity in the SCR of NO by propene.
Abstract(62) HTML(13) PDF 1070KB(9)
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Using cheap coal pitch as raw material and adding pore-forming agent, the carbon material with three-dimensional skeleton structure was obtained by mixing process, air oxidation stabilization process and carbonization process successively, and then the porous carbon material with high specific surface area was obtained by water vapor activation. Thermogravimetric and elemental analysis were used to study the thermal reaction characteristics and structural changes of the samples after oxidation stabilization and carbonization. The surface morphology, pore structure and electrochemical properties of the activated samples were characterized by scanning electron microscope, BET method and electrochemical workstation. After water vapor activation, BET of porous carbon can reach 1638 m2/g. The water-based double layer capacitors prepared with this porous carbon as the electrode material of supercapacitors have good cyclic performance, and the specific capacitance can reach 252 F/g at 1 A/g current density. After 10000 cycles, the specific capacity can still maintain 97.3%. Therefore, the porous carbon materials prepared by this method have low cost and good chemical stability, and can be used as an ideal electrode material for supercapacitors.
Abstract(44) HTML(9) PDF 2099KB(7)
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Limited by the steric hindrance, hydrogenation of the final unsaturated ring in polycyclic aromatic hydrocarbons remains a challenge. In this work, we prepared a series of Pt-Ni/NiAlOx catalysts by impregnation method to improve the adsorption of aromatics, and phenanthrene was served as the model compound. The effects of Pt content on the structure and saturation performance of Pt-Ni/NiAlOx catalysts were investigated systematically. When the saturation reaction was performed at 300 ℃, 5 MPa and a weight hourly space velocity of 52 h−1, the selectivity of perhydrophenanthrene could be improved from 40% over Ni/NiAlOx catalysts to 67% over 0.5Pt-Ni/NiAlOx catalysts with 0.5 wt% Pt loading. Meanwhile, the obvious reaction rate and turnover frequency were also improved from 1.53 × 10−3 mol/kg/s and 14.64 × 10−3 s−1 to 1.81 × 10−3 mol/kg/s and 22.16 × 10−3 s−1 respectively. This is related to the modified stability of metallic electron−deficient structure of Ni by Pt introduction in phenanthrene hydrogenation, which can promote the adsorption of aromatic hydrocarbons as well as the hydrogenation activity.
Abstract(49) HTML(19) PDF 1351KB(5)
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The Mo1Sn2 catalyst with a Mo/Sn molar ratio of 1∶2 was prepared by hydrothermal method, and the structure of molybdenum-tin catalysts was regulated by changing the calcination temperature (400−700 ℃), the effect of catalyst structure changes on the performance of selective oxidation of dimethyl ether (DME) to methyl formate (MF) was studied. The Mo1Sn2 catalyst calcinated at 400 ℃ was found to have good performance in the catalytic oxidation of DME to methyl formate, with the conversion of DME of 9.2% and the selectivity of MF up to 86.9% at 110 ℃ under atmospheric pressure, and no COx was generated. The structure and surface properties of the catalysts were systematically investigated by XRD, Raman, XPS, TPD, H2-TPR and in-situ IR. The results showed that low-temperature calcination was more favorable for the formation of more MoOx structures and Mo5+ species on the surface of the molybdenum-tin catalysts, and the resulting enhanced acidity, redox properties and increase of medium to strong basic sites of the catalysts could significantly promote the enhancement of the catalyst activity and methyl formate production.
Abstract(37) HTML(6) PDF 1270KB(5)
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The characteristics of the catalytic hydrogasification of activated carbon/bituminous char/anthracite char with the different catalysts were studied in a pressurized thermogravimetry analysis (PTGA). The GC, BET were used to characterize the physical structure and chemical reaction process of carbon, and the function principle of Co to the carbon-hydrogen reaction was preliminarily obtained. The results show that the catalytic activity of transition metals (Fe, Co, Ni) is significantly higher than that of alkali metals and alkaline earth metals in CCHG process. Transition metal CCHG process exists in low temperature (600−750 ℃) and high temperature (> 800 ℃), the emergence of the low temperature catalytic zone can be attributed to the interaction between the transition metal oxide and carbon, then part of carbon structure is activated. The transition metal is embedded in carbon layer structure, the effects of breaking C-C bond and proving the active hydrogen are more effective. Under the conditions of Co catalyst above 850 ℃ and 1 MPa hydrogen pressure, the hydrogen supply of the catalyst can reach saturation, and the catalytic hydrogasification process of carbon is mainly the catalytic bond breaking reaction induced by temperature. The model carbon with high specific surface area and low density has high CCHG activity with the low catalyst load.
Abstract(39) HTML(7) PDF 1367KB(2)
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Regioselective effects of electron and steric hindrance of catalytically active intermediate HCO(CO)2L by phosphine ligands on α-hexene hydroformylation were studied based on density functional theory. Strongly electron-attractive phosphine ligands raise the stability of HCo(CO)2L. PPh3 with large steric hindrance suppresses the adsorptive coordination of α-hexene to HCo(CO)2L, and the addition reaction of the C=C with the Co–H via the branched chain pathway. The difference in the energy barrier (ΔΔE) between B-TS1 for the branched chain alkyl Co intermediate transition state and L-TS1 for the linear chain one is 2.73 kcal/mol, indicating that the addition via the branched chain path is relatively difficult whereas that via the linear chain path advantage. The electron and steric hindrance of phosphine ligands both affect pathway of the addition reaction and are favor in the linear chain addition, with the linear chain aldehydes as main products.
Abstract(33) HTML(31) PDF 1136KB(7)
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BiOCl, BiOBr and BiOI were prepared by hydrothermal and solvothermal methods. XRD, SEM, photocurrent density curve and UV-vis were used to characterize the crystal structure, surface morphology and photoelectric properties. The band structure and density of states of BiOX were calculated by DFT, with the atomic number of halogen increased, the dispersion of the fermi level near the semiconductor conduction band decreased, the band gap becomes smaller. The photocatalytic activity of BiOCl, BiOBr and BiOI was evaluated by photocatalytic degradation of RhB, the degradation rate of RhB in 60 min for BiOI could reach 100%. Meanwhile, the main active groups in the process of photocatalytic degradation of Rhodamine B were explored by radical trapping experiment.
Abstract(28) HTML(35) PDF 1214KB(1)
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Uranium is a kind of radionuclide and also an important strategic resource. In some areas of China, the content of U in coal is extremely enriched. After high temperature transformation, U in coal would be enriched in solid products, which may cause radioactivity risk. In order to control the release of U and transform U in coal products into resource, it is necessary to investigate the migration law of uranium during thermal utilization of coal. Based on the thermodynamic equilibrium principle, this paper calculated and analyzed the morphology distribution of uranium in the pyrolysis, gasification and combustion processes of Ganhe coal, Xiao Longtan coal and Shengli coal. Also the influence of calcium based additives on U migration was analyzed, to provide theoretical guidance for subsequent experimental studies. The results show that: uranium has different forms under different thermal techniques; UO3(g) is the only gas phase product produced under different working conditions, and higher temperature, lower pressure and stronger oxidation environment will increase the amount of UO3(g); volatilization of uranium has been significantly week, since the fixation of uranium in calcium uranate. Especially, the amount of calcium uranate in Ganhe coal during combustion is increased obviously after the use of calcium based additives and the effect of CaO is the most significant.
Abstract(37) HTML(11) PDF 33390KB(4)
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In order to reveal the pyrolysis and coking characteristics of different components in coal, the macerals in Huangling coal were enriched by centrifugation, and the pyrolysis characteristics of macerals were studied. The transformation characteristics of macerals during pyrolysis were observed in-situ by heating stage microscope. The purities of vitrinite and inertinite are more than 90% and 80%, respectively, while the purity of liptinite is nearly 70%. The initial pyrolysis temperature of liptinite is about 385 ℃, and those of the other macerals are all about 410 ℃. The maximum pyrolysis temperatures are between 470−480 ℃ for all macerals studied. The maximum weight loss rate and the total weight loss rate decrease in the order of liptinite, vitrinite, semi-vitrinite and inertinite. The softening temperature of the liptinite (including sapropelic groundmass) is 350−370 ℃, while that of vitrinite is about 410−420 ℃ as shown by the in-situ pyrolysis in a heating stage microscope. The pyrolysis process of vitrinite goes through the stages of edge shrinking, pore formation, surface softening, the formation of liquid phase, and solidification. Only slight morphological changes are observed in semi-vitrinite, while no changes are observed in inertinite. The active components in Huangling coal are vitrinite and liptinite, and the liptinite can promote the softening and melting characteristics of the adjacent vitrinite.
Abstract(43) HTML(15) PDF 845KB(8)
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In this paper, the influence of NiO support on the synthesis of methanol from CO2 hydrogenation on In2O3(110) defect surface was studied with density functional theory (DFT). Two methanol synthesis pathways, namely HCOO pathway and reverse water gas (RWGS) pathway, were analyzed. The reaction energy and activation energy barrier of each elementary reaction involved in the HCOO and RWGS pathways were calculated. The results show that the NiO support can enhance the adsorption performance of In2O3 catalyst for CO2 and promote the generation of methanol through the HCOO reaction path. In the HCOO path, the hydrogenation of HCOO to H2COO is the rate-determining step for the HCOO reaction path, and the activation energy barrier is 1.66 eV. The NiO-supported In2O3(110) defect surface has a promoting effect on the hydrogenation of CO2, which is conducive to the synthesis of methanol from CO2 along the HCOO pathway, thus improving the efficiency of methanol synthesis from CO2 hydrogenation.
Abstract(25) HTML(6) PDF 976KB(3)
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Conductive carbon film has a wide range of application prospects, especially in the fields of electric heating devices, energy storage devices, and solar cells. Coal tar is an ideal precursor for preparing carbon film. In order to improve the performance of coal tar-based carbon film, it is necessary to study the influence of tar composition on the structure and performance of carbon film. In this paper, a carbon film is prepared using aromatic compounds, heteroatom compounds and tar as carbon sources. It is found that the carrier concentration of aromatic hydrocarbon-based carbon films is higher than 1022/cm3, but the mobility of the carrier is lower than 1 cm2/Vs. The resistivity and sheet resistance of the aromatic hydrocarbon-based carbon film are lower than that of the coal tar-based carbon film. Naphthalene-based carbon film has the best electrical and thermal properties. The maximum heating temperature of naphthalene-based carbon film at 30 V exceeds 300 °C. The thickness of the carbon film has a decisive influence on the sheet resistance of the carbon film. The performance of the heteroatom compound-based carbon film is significantly lower than that of aromatic compound-based film.
Abstract(26) HTML(3) PDF 465KB(4)
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The effects of pretreatment methods (DR, R, ROR) on the microstructure of Co/SiO2 catalysts and the activity for Fischer-Tropsch synthesis (FTS) were investigated. The pretreated catalysts were characterized by TEM, HRTEM, XRD, XPS, H2-TPD, TG and TPR. The results showed that after the pretreatments, specific morphological of the Co species changed, forming new Co active surface species. The Co particles redispersed and the Co species was facile to be re-reduced. The Co/SiO2 catalysts pretreated by different method showed different catalytic performance. The catalyst treated by the reduction-passivation had higher activity and ${\rm{C}}_{5}^ {+}$ selectivity for FTS.
Abstract(72) HTML(12) PDF 1561KB(12)
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Abstract(57) HTML(10) PDF 1175KB(4)
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In this work, the separation of phenol from oil mixtures was proposed by using mildronate (THP), Girard's Reagent T, and Girard's Reagent P. The results showed that the mentioned separation agents could form deep eutectic solvent (DES) with phenol and then separate phenol. The highest separation efficiency of phenol was 96.5% by THP, and the residual phenol content in oil was as low as 1.3 g/L; it was enough to finish separation in 10 min; the initial phenol content had no effect on the minimum residual phenol content (about 8.8 g/L) in oil after separation. An n-hexane washing method was used to remove the neutral oil entrained in DES. The results showed that the neutral oil to phenol mass ratio in DES was reduced to 0.04, which indicated that the purity of phenol product was greatly improved. THP was renewable and reused for 5 times, and its properties remained unchanged. Finally, FT-IR spectra showed that there was hydrogen bonds formed between THP and phenol.
Abstract(53) HTML(20) PDF 1457KB(6)
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In this study, the structure and combustion performance of pyrolysis chars from Daliuta raw coal, vitrinite-rich sample, inertinite-rich sample and demineralized coal sample were studied by Raman spectroscopy. The results showed that under the same pyrolysis conditions, compared with the pyrolysis char from Daliuta raw coal sample, the pyrolysis char from the demineralized coal sample has more large aromatic ring systems (≥ 6 rings), higher ignition temperature and much low combustion performance. The combustion performance of pyrolysis char from inertinite-rich sample is lower than that from vitrinite-rich sample, and the burnout capacity of pyrolysis char from inertinite-rich sample is far lower than that from vitrinite-rich sample. The ignition temperature (ti), the combustion reactivity index (tindex) and the wavenumber of D band (WD) in the Raman spectrum of Daliuta coal char has a good correlation, the correlation coefficients R2 obtained by the quadratic curve fitting are 0.9159 and 0.7133, respectively. There is no obvious correlation between burn-out temperature and WD of Daliuta coal char, indicating that the carbon structure of Daliuta coal char has a significant impact on the ignition temperature and combustion reactivity index of the char, but is no regular effect on the burn-out ability of the char.
Abstract(50) HTML(14) PDF 1399KB(5)
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Tanning sludge, chrome tanned buffing dust and chrome shavings were selected as experimental materials. The non-isothermal distributed activation energy model (DAEM) was used to study the pyrolysis kinetic parameters. The effects of particle size and temperature on the distribution of co-pyrolysis products of various tanning wastes were investigated in a fixed-bed pyrolysis reactor, which provided a new approach for comprehensive thermal treatment of various tannery wastes. The results showed that the total activation energy required for the co-pyrolysis decreased and then increased in the range of conversion rate of 0.1 to 0.8. The tar yield decreased with raising particle size, while the yields of gas and char increased. With the increase of pyrolysis temperature, the tar yield increased rapidly to a peak value of 17% at 600 ℃, and then decreased, correspondingly the char yield decreased while the gas yield increased. When the pyrolysis temperature was 600 ℃ and the particle size of the material was 1.6–2.5 mm, the specific surface area of char was larger, and the light fractions in tar was higher. Thus the co-pyrolysis was conducive to the clean treatment of tannery wastes.
2021, 49(10): 1-8.
Abstract(31) HTML(15) PDF 8395KB(11)
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2021, 49(10): 1389-1401.   doi: 10.1016/S1872-5813(21)60117-2
Abstract(101) HTML(24) PDF 1458KB(34)
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Carbon disulfide (CDS), methanol, acetone and isometric carbon disulfide/acetone mixture (IMCDSAM) were used as solvents to sequentially extract Naomaohu lignite (NL) via ultrasonic-assisted extraction to obtain extracts (E1−E4) and final extraction residue (ER). Composition and structure of E1−E4 were analyzed by GC-MS. It is found that the main compounds in E1 are alkanes, aromatics, alcohols and esters. Alkanes, alcohols and esters are the main compounds in E2. Alcohols, phenolics and esters are the main components in E3, and esters are mainly phthalic diester compounds. Affected by synergistic effect of the two solvents CDS and acetone, the relative content of alkenes in E4 is relatively high. FT-IR was used to characterize functional groups in NL, E1−E4 and ER. The results show that the ultrasonic extraction process only extracts free small compounds from macromolecular skeleton of the NL and some other molecules, which connect the macromolecular skeleton by weak covalent bonds, and the process does not destroy the macromolecular skeleton structure. In addition, peak fitting results from FT-IR show that types of infrared absorption peaks in ER do not change after ultrasonic extraction, while intensity of the peaks varies. TG-DTG profiles of NL and ER indicate that after ultrasonic extraction weight loss of NL increases from 47.09% to 51.04%, and peak of the maximum weight loss rate is advanced from 450 to 430 ℃. Pyrolysis kinetic analyses of NL and ER based on Coats-Redfern model show that after ultrasonic extraction activation energy of ER in rapid pyrolysis stage is lower than that of NL, and the pyrolysis process is easier to proceed.
2021, 49(10): 1402-1411.   doi: 10.1016/S1872-5813(21)60156-1
Abstract(62) HTML(6) PDF 1170KB(9)
Abstract:
A novel and highly active nitrogen-doped porous carbon-supported nickel catalyst Ni@N-PC was successfully developed by a thermolysis of nickel-based zeolitic imidazolate frameworks growing on both sides of graphitic carbon nitride and used for catalyzing hydroconversion of isopropanol soluble portion from ultrasonic extraction of high-temperature coal tar (ISPHTCT). The active nickel nanoparticles were mainly encapsulated on the top of carbon nanotubes and partially dispersed on the surface of carbon nanosheets. Naphthalen-1-ol was used as a model compound to investigate the catalytic hydroconversion activity under different reaction conditions and reveal the mechanism for catalytic hydroconversion. The ISPHTCT and catalytic hydroconversion products of ISPHTCT (ISPCHCP) were analyzed with gas chromatograph/mass spectrometer. The results show that 70% of naphthalen-1-ol was converted at 160 °C and completely converted at 200 °C for 120 min, and the ISPHTCT was greatly upgraded. A total of 180 organic compounds including 33 nitrogen-containing organic compounds, 11 sulfur-containing organic compounds and 39 oxygenates were identified in ISPHTCT, while no obvious nitrogen-containing organic compounds, sulfur-containing organic compounds and oxygenates were detected in ISPCHCP, indicating the excellent performance of Ni@N-PC for heteroatom removal. All the alkenes, cyclenes and alkynes were saturated and the majority of arenes were converted to cyclanes by catalytic hydroconversion over Ni@N-PC, which exhibited high catalytic hydrogenation activity.
2021, 49(10): 1412-1420.   doi: 10.19906/j.cnki.JFCT.2021057
Abstract(96) HTML(38) PDF 1399KB(27)
Abstract:
Mosaic coke is a kind of special artificial carbon material, which is usually used as the raw material to produce high-quality nuclear graphite. The quality of graphite has been usually focused on the properties of mosaic cokes. In order to investigate the influence of the quinoline insoluble (QI) content of heavy-phase pitch on the micro-structure and properties of mosaic coke, 9 kinds of heavy-phase pitches with varied QI contents were used as the raw materials to produce series of mosaic cokes in this study. Optical micro-scope, scanning electronic micro-scope, X-ray diffraction, Raman spectrum and curve-fitted methods were used to judge the micro-structure of 9 kinds of mosaic cokes. Also, the micro-strength of mosaic cokes was determined. The results show that the higher content of QI in heavy-phase pitch has the mosaic structure easier to be produced during the liquid-phase carbonization process. What’s more, with the increase of QI content, the content of regular carbon microcrystals decreases, but the content of amorphous carbon and micro-strength are improved. When the QI contents in the heavy-phase are higher than 7%, the derived mosaic cokes have the total contents of mosaic structure (the sum of fine mosaic structure, medium mosaic and coarse mosaic) higher than 82% and the micro-strength higher than 85%. In other words, the heavy-phase pitch with the content of QI higher than 7% is a promised raw material to produce high-quality mosaic coke.
2021, 49(10): 1421-1434.   doi: 10.1016/S1872-5813(21)60127-5
Abstract(174) HTML(46) PDF 1861KB(13)
Abstract:
Recently, the disposal of waste by beneficial and environmentally friendly methods has attracted great attention. In this work, we have studied the production of high-value carbon nanotubes (CNTs) which have remarkable applications by catalytic pyrolysis of sugarcane bagasse (SCB) as an agricultural waste using a two-stage process. Various reaction factors including the effects of zeolite types (HZSM-5, HMOR, and HY), pyrolysis temperatures (450−700 °C), and SCB/ZSM-5 ratios (3−12) on SCB pyrolysis were investigated to generate CNTs from pyrolysis products. A Co-Mo/MgO catalyst was used for growing CNTs via the decomposition of pyrolysis products. The morphological structure and quality of CNTs were characterized using TEM and Raman spectroscopy, while the fresh Co-Mo/MgO catalyst was characterized by XRD and TPR analyses. The results showed that zeolite type, pyrolysis temperature, and SCB/ZSM-5 ratio had significant effects on the CNTs yield. The optimum carbon yield (24.9%) was achieved using the HZSM-5 catalyst at the pyrolysis temperature of 500 °C and with the SCB/ZSM-5 ratio of 6. TEM observations confirmed the growth of bamboo-like carbon nanotubes (BCNTs) and carbon nano-onions (CNOs) in different proportions according to the reaction parameters. Also, CNTs with the largest diameter distribution range (7−76 nm) were produced using the SCB/ZSM-5 ratio of 6. Raman spectra demonstrated the production of high-quality CNTs under all studied conditions.
2021, 49(10): 1435-1443.   doi: 10.1016/S1872-5813(21)60092-0
Abstract(118) HTML(19) PDF 1240KB(31)
Abstract:
A molecular modeling based on the density functional theory (DFT) and the transition state theory (TST) was performed to investigate the influence of biomass gas CO on the N2O decomposition catalyzed by CaO during reburning in the circulating fluidized bed boiler. The model for N2O adsorption onto the CaO(100) surfaces were constructed; and the processes of the N2O decomposition on the CaO(100) surface and the surface recovery of CaO(100) were investigated. The results illustrate that the energy barrier of N2O decomposition on the CaO(100) surface is much lower than that in homogeneous case, and CaO is therefore able to catalyze the N2O decomposition. The atomic O from N2O decomposition can poison the active sites O atom on the CaO(100) surface, while biomass gas CO can promote the regeneration of the active sites on the surface of CaO(100), which is beneficial for CaO to catalyze the N2O removal.
2021, 49(10): 1444-1457.   doi: 10.1016/S1872-5813(21)60097-X
Abstract(136) HTML(50) PDF 1829KB(36)
Abstract:
The dramatic increase in atmospheric CO2 concentrations has attracted people's attention, and many strategies have been developed to convert CO2 into high-value chemicals. Metal-organic frameworks (MOFs), as a class of versatile materials, can be used in the CO2 capture and conversion because of their unique porosity, large specific surface area, rich pore structure, multiple active centers, good stability and recyclability. Various functional nanomaterials have been designed and synthesized based on metal organic framework (MOF) of crystalline porous materials to meet these challenges. Herein, in this review, the latest processes of MOFs in field the of CO2 hydrogenation to carbon monoxide, methane, formic acid, methanol and olefins are summarized, and the synthesis methods of catalysts based on MOFs and the reasons for their high catalytic activity are analyzed. Besides, a brief introduction to improve the catalytic activity of the new MOF material and explore the feasible strategies for CO2 conversion are advised. Finally, the paper discusses the main challenges and opportunities of MOF-type catalysts in CO2 chemical conversion, and presents a brief outlook on further developments in this research area.
2021, 49(10): 1458-1467.   doi: 10.1016/S1872-5813(21)60100-7
Abstract(105) HTML(27) PDF 1377KB(18)
Abstract:
Zn-doped and Zn-Al co-doped La2O3 catalysts were prepared by citric acid sol-gel method and characterized by a series of in situ technologies, to investigate the structure-activity relationship of La2O3-based catalysts in the oxidative coupling of methane (OCM). The in situ XRD results reveal a thermal expansion of the La2O3 crystal along the c-axis at high temperature. The H2-TPR results show two types of oxygen species on the La2O3-based catalysts, viz., the strong-binding oxygen species and weak-binding oxygen species; in addition, the XPS results indicate that the strong-binding oxygen species is probably attributed to anion radical O. The doping with Zn can significantly increase the number of oxygen vacancies in the Zn-doped La2O3 catalysts, which can promote the activation of oxygen and generate more strong-binding oxygen species; as a result, the Zn-doped La2O3 catalyst shows better performance in OCM in comparison with the unmodified La2O3 catalyst. Moreover, the co-doping with Al can promote the dispersion of Zn in La2O3 and further raise the number of strong-binding oxygen species in the Zn-Al co-doped La2O3 catalysts, which is beneficial to enhance the selectivity to C2+ hydrocarbons in the OCM reaction
2021, 49(10): 1468-1486.   doi: 10.1016/S1872-5813(21)60130-5
Abstract(56) HTML(10) PDF 1104KB(6)
Abstract:
Effects of calcium content on the performance of HZSM-5 nanoparticles of 150 nm with Si/Al ratio = 230 in the methanol to olefin conversion were investigated. The parent and modified catalysts showed their largest yields of ethylene and propylene at 490 °C and lower WHSV (= 3.3 h−1). The selectivity for propylene over HZSM-5 was 0.45 at 490 °C whereas it was promoted to 0.51 over Ca27-HZSM-5 (Ca/Al = 27). With decreasing temperature from 490 to 440, and 390 °C, the yield of propylene and ethylene remained nearly constant at 0.13−0.14 and 0.10−0.11 over Ca27-HZSM-5, respectively; more narrow than the corresponding range of yields for HZSM-5 (0.10−0.14 and 0.08−0.12). FT-IR results confirmed the formation of oxygenated and poly alkyl aromatic species in the carbon deposits. TG results indicated that oxygenate coke was formed and converted to heavier poly aromatic coke species with time. Increasing Ca in the porous structure of HZSM-5 may lead to heavier aromatic carbonaceous deposits. In general, Ca content positively affected activity through modification of the density, strength, and accessibility of Brønsted and Lewis acid sites. Long-term MTO activity test of HZSM-5 with Ca/Al = 27 showed stable performance over 100 h, although with an oscillatory feature.
2021, 49(10): 1487-1494.   doi: 10.1016/S1872-5813(21)60094-4
Abstract(154) HTML(16) PDF 1250KB(26)
Abstract:
A new Mo-Sn catalyst prepared by hydrothermal method was used for the synthesis of dimethoxymethane (DMM) from methanol oxidation. The catalyst with low Mo content can achieve low-temperature oxidation of methanol to DMM with high selectivity. The influence of Mo content on the structure and the catalytic performance of the catalyst was investigated. It was found that Mo1Sn10 catalyst showed the best catalytic performance under the conditions of 140 °C and atmospheric pressure, the methanol conversion was 14.2%, and the selectivity of DMM reached 88.9% without the formation of COx during the reaction process. The catalysts were characterized by XRD, Raman, FT-IR, XPS, NH3-TPD and H2-TPR. The results showed that the catalysts with different Mo content had obvious differences in structure and performance. Lower Mo content was more conducive to the formation of Mo5+ and MoOx, and the resulting changes in acidity and redox properties were the important reasons for the excellent performance of the catalysts.
2016, 44(4): 385-393.
[Abstract](120) [FullText HTML](83) [PDF 1138KB](9)

2016, 44(7): 777-783.
[Abstract](133) [FullText HTML](53) [PDF 2169KB](4)

2016, 44(3): 263-272.
[Abstract](56) [FullText HTML](61) [PDF 1275KB](4)

2016, 44(7): 801-814.
[Abstract](148) [FullText HTML](75) [PDF 8665KB](19)

2016, 44(11): 1388-1393.
[Abstract](94) [FullText HTML](59) [PDF 780KB](4)

2016, 44(3): 279-286.
[Abstract](95) [FullText HTML](55) [PDF 12189KB](4)

2016, 44(6): 732-737.
[Abstract](77) [FullText HTML](39) [PDF 2776KB](3)

2016, 44(9): 1034-1042.
[Abstract](106) [FullText HTML](49) [PDF 809KB](2)

2018, 46(2): 179-188.
[Abstract](72) [FullText HTML](33) [PDF 7028KB](5)

2017, 45(1): 113-122.
[Abstract](76) [FullText HTML](43) [PDF 1085KB](4)

2013, 41(08): 1003-1009.
[Abstract](2054) [PDF 13334KB](2)
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](1518) [PDF 0KB](8)
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.