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Abstract(107) HTML(18) PDF 4476KB(9)
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Carboxylic ionic liquid 1-propionic acid-3-methylimidazolium chloride (CFIL) was one-pot immobilized into a metal-organic framework material NH2-MIL-101 by in-situ assembly method. Heterogeneous catalyst with multiple active sites was thus prepared for the cycloaddition reaction of CO2 and epichlorohydrin (ECH) to synthesize chloropropylene carbonate (CPC). Fourier transform infrared spectroscopy (FT-IR) and elemental analysis proved the successful introduction of CFIL, and powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and N2 adsorption-desorption (BET) demonstrated CFIL did not damage the crystal structure and block the pore of NH2-MIL-101, while induce the formation of mesopores. Under the synergistic effect of imidazole N and Cl on CFIL and Cr3+ and amino group on MOF, induced catalyst under mild conditions (0.1 MPa CO2, T=25−70 ℃, 24h, without solvent and the addition of a cocatalyst), efficient catalytic conversion of CO2 to chloropropylene carbonate (yield and selectivity can reach 99%). The catalyst can still maintain high activity and stable crystal structure after 5 recycles.
Abstract(35) HTML(13) PDF 0KB(4)
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The Ni and Ce transition metal catalyst supported by modified activated coke prepared by constant volume impregnation method can realize the simultaneous removal of NO and CO at low temperature and oxygen enrichment. Ni-Ce/AC-N can achieve efficient conversion of NO and CO at 175–250 ℃, and the conversion of NO and CO is higher than 95% at this temperature range. After modified by nitric acid, the active coke carrier has stronger interaction with metal components, which is conducive to better dispersion of active components on the catalyst surface, and improve the specific surface area and redox capacity of the catalyst. The synergistic effect between Ni and Ce resulted in more Ni2+ and Ce3+ on the catalyst surface, which was conducive to the improvement of catalytic activity.
Abstract(35) HTML(24) PDF 0KB(9)
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Medium temperature coal tar pitch (ZCTP) was separated by Soxhlet extraction using toluene-pyridine and n-heptane-tetrahydrofuran as solvents to obtain the group components. Then, their composition and structure were analyzed. The results showed that, in comparison with ZCTP, toluene-insoluble pyridine soluble (TI-PS) and n-heptane-insoluble tetrahydrofuran soluble (HI-THFS) are more thermally stable, exhibiting a decrease weight loss of 41.51% and 28.85% and an increase residual carbon rate of 56.95% and 47.63%, respectively. In addition, the C=C content of TI-PS and HI-THFS was 6.69% and 3.26% higher than that of ZTCP, reaching 75.57% and 73.14%, and the pyridine nitrogen content of TI-PS and HI-THFS increases about 16 and 8 percentage points. Both TI-PS and HI-THFS were used to prepare mesophase pitch. It is found that M-HI-THFS is mainly consisted of small and medium area type with some fine mosaic structure and low optical anisotropy content. While M-TI-PS has about 80% optical anisotropy content and displays a wide range of optical weave. However, it is difficult for ZCTP to form a stable regional optical fabric structure, just exhibiting a mosaic optical fabric.
Abstract(40) HTML(21) PDF 0KB(5)
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Transition metal oxide is a kind of catalyst with high catalytic activity for electrocatalytic oxygen evolution reaction. However, the catalytic activity is limited by the low electronic conductivity. The effective way to construct high performance electrode material or electrochemical catalyst is combining the nano material with conductive matrix material. The polymerized porphyrins supported on C3N4 were prepared by solvothermal method. The Co3O4/NC catalyst was prepared by Co modification and heat treatment of BDA-PY/C3N4. The physicochemical properties of the catalyst were characterized by XRD, SEM, TEM, XPS and FT-IR, and so on. The results indicated that Co3O4/NC-600 possesses a super-small nano-Co3O4 structure and high nitrogen content. The strong chemical bond between pyridine N of the nitrogen-doped carbon and Co is formed, resulting in a synergistic effect, which makes the catalyst show good catalytic performance in OER reaction. Its Tafel slope is only 66.4 mV/dec and the minimum overpotential is 343.3 mV when the current density reaches 10 mA/cm2.
Abstract(65) HTML(49) PDF 1133KB(7)
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Interactions of potassium-based catalysts with Shenfu (SF) char during catalytic gasification was observed by an in-situ heating stage microscope. The effects of the gasification temperature (800−900 °C) and the catalyst loading (4.4%, 10%) on the reactivity of coal char were investigated. The heating stage microscopy was used to visualize the catalytic gasification process of coal char particles and the fractal theory was introduced to analyze the surface structure of coal char particles to reveal the gasification reactivity. The experimental results show that the fractal dimension of coal char particles is positively correlated with the carbon conversion rate, and the fractal dimension increases by increasing the gasification temperature and the catalyst loading. The relationship between the initial gasification reaction rate and the fractal dimension of coal char particles is consistent with that between the carbon conversion rate and the fractal dimension of coal char particles. There is an exponential relation between the fractal dimension of coal char and the char angle; the fractal dimension increases with the increase of coal char particle angle; and the fractal dimension of coal char particles can be used in the study of coal char catalytic gasification process.
Abstract(96) HTML(62) PDF 2390KB(16)
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As the most abundant and renewable aromatic source on the Earth, lignin is a good alternative to fossil fuel on producing versatile petrochemicals and biofuel. However, current techniques for lignin conversion generally suffer from some key problems of harsh reaction condition and low selectivity of products. In this study, an efficient process was provided for selective depolymerization of herbaceous lignin to a fine chemical of methyl p-coumarate (MPC) by using cost-effective catalysts of metal oxides. The influences of different metal oxides, reaction temperature, time and solvent on the yield and selectivity of MPC were systematically investigated. The results showed that ZnO exhibited the best catalytic activity, where the yield and selectivity of MPC reached 9.80% and 61.6%, respectively, at the optimized reaction conditions. Furthermore, the results of products distribution and comparative investigation on the raw and unreacted lignin using FT-IR and 2D HSQC NMR spectra demonstrated that the efficient cleavage of the ester linkage in lignin was responsible for this good MPC yield and selectivity. Therefore, this work provides a new insight on producing fine chemicals from the renewable lignin.
Abstract(47) HTML(12) PDF 1559KB(12)
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Cellulose is one of the most abundant renewable organic carbon resources in the world. Levoglucosenone (LGO) is a high value-added platform chemical derived from cellulose pyrolysis. In this study, the influence of ionic liquid catalyst on the production of LGO by catalytic pyrolysis of cellulose is revealed. The results showed that 1-butyl-2,3-dimethylimidazolium triflate performed best for the LGO formation, the reason is that the decrease in the length of the side chain weakens the interaction between the cation and anion of the ionic liquid, which increases the diffusion of the ionic liquid. LGO reached a yield of 15.6 %-C at pyrolysis temperature of 300 ℃, and the recovery rate of ionic liquid attained to 95.9%. Besides, LGO yield only slightly decreased after three times re-utilization of the ionic liquid. The formation path of LGO was calculated by density functional theory, and the result showed the lowest activation energy was 176.2 kJ/mol. Moreover, this method is also effective to obtain porous char at the same time, and the highest specific surface area and pore volume are 389.4 m2/g and 0.689 cm3/g, respectively.
Abstract(44) HTML(8) PDF 8415KB(4)
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In this paper, ZhunDong coal was selected as the precursor of carbon material and activated by hydrothermal coupling with trace K element. Through experiments, the influence of K concentration on carbon adsorption performance was explored, and the NOx low temperature adsorption performance of the material was systematically studied. The experimental results show that when the concentration of K2CO3 in the activation solution is 0.01 g/mL, the prepared sample has a good NOx adsorption performance, and the saturated NOx adsorption time is 3200 s. By N2 physical adsorption at low temperature, it was found that the pore structure of the sample developed well at this concentration, and the specific surface area reached 708.6 m2/g. In addition, the article by XPS, SEM and other means to different concentrations of K2CO3 activated carbon material has carried on the physical and chemical characterization, and the different concentration of K2CO3 activate the preparation of the surface properties of samples analysis, and through the FT-IR study of adsorption process on the surface of the sample, founding ZhunDong coal carbon material excellent adsorption properties and surface structure, In this study, DFT method was used to verify the reaction mechanism. The results showed that K could promote the formation of C–O bond, and the active C–O structure was the key factor promoting NOx adsorption. Through a series of experiments, the best method and optimal process parameters of preparing ZhunDong coal-based carbon materials by hydrothermal coupling trace K were obtained.
Abstract(26) HTML(8) PDF 2523KB(5)
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Pyrolysis behavior and kinetics of typical agroforestry biomass such as apricot shell, wheat straw and poplar sawdust were investigated by thermogravimetric mass spectrometry (TG–MS). The results showed that the differences of the main components made the three biomasses exhibited different characteristics in the main reaction range (200–450 ℃). It was found that the average activation energy of apricot shell, straw and sawdust was 188.22 kJ/mol, 220.77 kJ/mol, and 175.87 kJ/mol, respectively by using the typical isoconversional methods. The average activation energy of each component in biomass was calculated by the distributed activation energy model (DAEM) method, and it was found that there was a fourth component with high average activation energy in biomass (apricot shell being 297.44 kJ/mol, straw being 284.35 kJ/mol and sawdust being 309.96 kJ/mol). The activation energy of hemicellulose and cellulose showed the relationship of straw < apricot shell < sawdust. The two kinds of kinetics methods are complementary to each other. The overall calculation results of the isoconversional method are close to those of the single-component distributed activation energy model method, and the method is simpler. The distributed activation energy model method can obtain the kinetic parameters of different components of raw materials, which makes up for the deficiency of the isoconversional method. Comprehensive use can form a more comprehensive understanding of the pyrolysis reaction.
Abstract(60) HTML(39) PDF 3470KB(8)
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Corn straw was torrefied under atmospheric pressure (AP) and gas pressured (GP) at different temperature and gas pressure in order to verify the influence of gas pressure on the torrefaction of biofuel. The proximate analysis, ultimate analysis, FT-IR, TGA and pyrolysis experiments were conducted to explore the characteristics of torrefaction products under different conditions. The results show that the deoxidation efficiency and energy density of samples torrefied under both AP and GP conditions increased with the increase of torrefaction temperature. The temperature required for GP torrefaction is almost 40 ℃ lower than that of AP torrefaction when the same mass yield is obtained. The energy yield, carbon yield, deoxidation efficiency and the energy density of GP torrefaction products are 1.125, 1.142, 1.539 and 1.131 times higher than those of AP torrefaction products respectively. GP torrefied samples show better hydrophobicity and are easier to dehydrate. The volume fractions of CH4 and H2 in the product gas of corn straw pyrolysis after GP torrefaction are significantly higher than those after AP torrefaction. The concentration of CH4 and H2 in the pyrolysis gas of GP torrefied samples at 250 ℃ are 2.135 and 1.439 times higher than those of AP torrefied samples at 250 ℃, respectively. The relative contents of phenols in the liquid pyrolysis products of GP torrefied samples increase up to 51.11%, while the contents of furans and acids decrease significantly. The results indicate that GP torrefaction performs better in biofuel upgrading than AP torrefaction under the same temperature.
Abstract(34) HTML(27) PDF 1001KB(6)
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In this paper, a low-volatile bituminous coal C1 and a high-volatile bituminous coal C2 were selected as research objectives, a lignite L1 and two semi-cokes produced from pyrolysis of C2 at two temperatures were used as the control. The permeability tests of single coal, binary coal or semi-coke and separated combination were conducted. The influence of volatiles release behaviors on the evolution of permeability of plastic layer was revealed by thermogravimetric and fluidity analyses. The main results are as follows. There was a low permeability plateau stage of plastic layer of C1, while the permeability of plastic layer of C2 was rapidly improved after reaching the lowest. That result was related to the difference on the mass transfer conditions of volatiles from two coals. C2 could enhance the mass transfer driving force of volatiles and bring both inert components (semi-coke after pyrolysis) and transferable hydrogen, thus the permeability of plastic layer could be improved without destroying the stability of plastic layer. The hydrogen-rich volatiles released from C2 before its initial softening temperature helped the low permeability of the plastic layer of C1 be formed and reach the maximum. The volatiles released during the plastic stage of C2 helped maintain the low permeability plateau of plastic layer of C1. It was plausible to further improve the permeability of plastic layer of C1 by consuming part of hydrogen-rich volatiles from C2 when prolonging the volatiles’ reaction.
Abstract(48) HTML(7) PDF 1788KB(13)
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To address the slagging problem during coal entrained-flow bed (EFB) gasification, the influences of textile dyeing sludge (TDS) addition on the fusing characteristics of high ash fusion temperature (AFT) coal were explored under a reducing atmosphere. And the change mechanisms were investigated by X-ray diffraction, Fourier Transform Infrared Spectroscopy (FT-IR) and FactSage calculation. The results showed that the flow temperature of high ash fusion temperature (AFT) coal decreased below 1380 °C when the TDS addition reached 20%−25%, which met the requirements of liquid-slag removal for EFB gasification. With the content of TDS increasing, the formations of low-melting minerals (e.g., hercyniye, anorthite, and albite) decreased AFT. The bridging oxygen bonds of the network structure were destroyed by metal ions (e.g., Fe2+, Ca2+, Na+), formation of much non-bridged oxygen (NBO) bonds relaxed the silicate network, thus decreasing the AFT. The formations of NBO bonds were confirmed by gradual decreases in the peak strengths of Si−O−Si and Si−O−Al bonds and intensified the vibration of Fe−O and Si−O−M ( M: Ca2+ or Na+) bonds. FactSage calculation results were in good agreement with the experimental ash fusion behavior.
Abstract(46) HTML(45) PDF 1311KB(4)
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The pyrolysis desulfurization experiments of two kinds of Shanxi high-sulfur anthracite coal under hydrogen atmosphere were carried out using a micro fluidized bed reaction analyzer (MFBRA) integrated with a rapid online gas analyzer. The dynamic release characteristics of sulfur-containing gas and the transformation between sulfur-containing components in the resultant char during the pyrolysis process were analyzed based on the results of morphological and XPS characterizations. The results showed that the dynamic release curves of two anthracite coals during pyrolysis at hydrogen atmosphere were characterized by two intensity peaks at 530 ℃-560 ℃ and 812 ℃-830 ℃, respectively, indicating that the sulfur release completed by two subsequent processes. Analysis of the experimental results determined that the first process was resulted from the reduction reaction of pyrite, and the second was due to organic sulfur decomposition. It was revealed that the migration from inorganic to organic sulfur occurred predominately at lower temperatures, while transformation between different forms of organic sulfur components was dominant at higher temperatures. The research results provide the essential data supporting the development of highly efficient pyrolysis desulfurization technology for clean and efficient utilization of high sulfur anthracite coal resources.
Abstract(93) HTML(17) PDF 978KB(16)
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A bifunctional catalyst of Ru5/ASA-TiO2 was prepared by using a novel silicon-aluminum (ASA)-TiO2 amorphous composite, which was synthesized by a steam-assisted method, as the support. X-ray diffraction (XRD), pyridine adsorption infrared (Py-FTIR), ammonia-temperature-programmed desorption (NH3-TPD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and other methods were used to characterize the structure and the acidity of the prepared catalyst. Using diphenyl ether as the lignite-related model compound, the reaction activity of the Ru5/ASA-TiO2 for the catalytic hydrogenolysis of 4–O–5 type ether bonds was investigated under a mild condition. The results show that the weak acid and/or the Lewis acid rather than the strong Brønsted acid mainly contribute to improve the conversion rate and the benzene yield of the catalytic hydrogenolysis of diphenyl ether. The reaction temperature can influence the relative content of various types of acids to significantly affect the selectivity of the hydrogenolysis products of diphenyl ether. The conversion rate of diphenyl ether is greater than 98% while the benzene yield is 67.1%.
Abstract(81) HTML(75) PDF 770KB(11)
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As a typical saturated bicyclic compound, decalin is normally used as a probe molecule of saturated cycloalkanes for the mechanism study of selective ring-opening reaction during the hydrogenation of light cycle oil. In this review, the molecular structure and reaction characteristics of cis-decalin and trans-decalin are introduced. The mechanism of the selective ring-opening reaction of decalin based on different catalytic systems is systematically analyzed, including the carbocation mechanism on monofunctional acid catalysts, the hydrogenolysis reaction mechanism on monofunctional metal catalysts, and the bifunctional ring-opening reaction mechanism on acid-metal bifunctional catalysts. In addition, the effect of the process conditions, such as reaction temperature, support acidity and zeolite pore size, on the performance of selective ring-opening reaction of decalin are summarized. Finally, the shortcomings of current research are put forward, and the urgent and deserved research topics are proposed.
Abstract(159) HTML(55) PDF 1621KB(16)
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In the industrial circumstances, sulfur-containing species are frequently present in the exhaust gas, such as methane, ethane and volatile organic compounds (VOCs). These species may occupy the active sites on the catalyst surface during the oxidation reaction, causing temporary physical deactivation of the catalyst. Moreover, permanent deactivation might occur when sulfur-containing species react with the active sites, which thereby causes the poisoning and invalidation of the catalysts. This paper reviewed the anti-toxicity properties of precious metals, metal oxides composites and perovskite-type catalysts adopted in the catalytic combustion of exhaust, the detailed poisoning mechanism of the catalysts was discussed, basing upon which the way to improve the anti-toxicity of the catalyst was also proposed, This review may provide some insight into the development of catalysts with high resistance to sulfur poisoning.
Abstract(37) HTML(32) PDF 1719KB(3)
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A serial of Fe modified Zr-based montmorillonites were prepared by mechanical ball milling and their characteristics were depicted by X-ray diffractometer (XRD), N2 adsorption-desorption instrument (BET), temperature-programmed desorption of ammonia (NH3-TPD, H2-TPD), X-ray photoelectron spectrometer (XPS). The results show that compared with 24ZrAM, when FeCl3·6H2O and FeCl2·4H2O are used as iron sources, Fe–O–Zr structure appears on the 3Cl-24ZrAM and 2Cl-24ZrAM catalysts. In the presence of Fe sulfate, the specific surface area of the catalysts decrease markedly. With the introducing of Fe, the total acid content of catalysts reduces. Wherein, 3Cl-24ZrAM has the highest acid content and strongest acid strength. H2-TPR shows that the temperature for Fe2O3 being reduced to Fe3O4 in 3Cl-24ZrAM, 2Cl-24ZrAM and $3{\rm{NO}}_3^ -$-24ZrAM is lower than 500 ℃. Then, the effect of catalysts on the pyrolysis behavior of Xinjiang Hefeng coal and the bridge bond cleavage mechanism of different model compounds were investigated in a fixed bed reactor. It is noted that compared with 24ZrAM, the fraction of coal tar pitch all declines under the action of Fe species. Among them, 3Cl-24ZrAM has the highest cracking activity with the light tar fraction of 63%, which is 18.9% higher than that of 24ZrAM. Meanwhile, the content of light oil and phenol oil are 1.3 times and 1.4 times than that of 24ZrAM, respectively. As for long-chain hydrocarbons, a further decline by 0.7% is observed. In addition, the conversion rates of Benzyl phenyl ether (BPE), dibenzyl and biphenyl increase by 5%, 1.6% and 43.9%, respectively.
Abstract(60) HTML(12) PDF 1632KB(5)
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The distribution of Hongshaquan coal's alkaline (earth) metals and their influence on coal char gasification reaction activity under different gasification conditions were investigated in a high-temperature gasification fixed-bed experimental system. The results showed that the Na discretely distributed on the char surface at low temperature, while it showed a slight aggregation phenomenon when the gasification temperature was higher than ash fusion temperature. During the gasification process, the K was evenly distributed on the char surface. The enrichment of Ca and Mg elements on the surface of coal char was relatively obvious. The migration clusters of calcium-containing and magnesium-containing minerals formed large-sized ash sphere in the depressions on the surface of coal char. There was a certain dependence on the distribution of the above two elements. As the carbon conversion increased, the apparent activation energy and pre-exponential factor all increased, the reactivity of coal char became worse.
Abstract(41) HTML(14) PDF 915KB(5)
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With consumption of high quality coal resources, clean and efficient conversion of high sulfur coal has attracted much attention, and especially the regulation of organic sulfur in high sulfur coking coal is very important. During pyrolysis transformation of organic sulfur in coal begins with cleavage of C-S bonds in the macromolecular structure of coal and stabilization of sulfur-containing free radicals, and active hydrogen/oxygen is an important factor affecting the transformation behavior of organic sulfur. It is found that, during coal pyrolysis under hydrogen-enriched or oxygen-enriched atmosphere or co-pyrolysis with biomass or oxygen-containing organic matter, the active hydrogen/oxygen in the system can weaken C-S bonds of organic sulfur, and promote their cleavage, timely combination with the generated sulfur-containing free radicals. This can promote sulfur in coal transform to the gas phase and reduce the secondary reaction of sulfur-containing free radicals with coal matrix. At the same time, during co-pyrolysis of high volatile and high sulfur coals, the relatively abundant active hydrogen/oxygen in volatile will also affect the organic sulfur transformation behavior in high sulfur coal, and reduce the sulfur content in coke, which provides a theoretical basis for directional regulation of sulfur in coal.
Abstract(50) HTML(29) PDF 621KB(1)
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Co-gasification of agroforestry waste biomass and coal realizes energy-saving, low-carbon, clean and efficient raw material conversion by taking advantage of their similarities and complementarities. The physicochemical properties of ash slag for raw materials are one of the key factors affecting the stable operation of co-gasification. It is the focus of co-gasification research. This paper reviews the research status about of physicochemical properties of ash slag from co-gasification of agroforestry waste biomass and coal. It mainly includes the similarity and difference between agroforestry waste biomass ash and coal ash, the fusion and viscosity-temperature characteristics of mixed ash, the effect of alkali/alkaline earth metals in mixed ash on co-gasification reactivity and sintering behavior during slagging process. The influence mechanism of adding agroforestry waste biomass on the melting flow and sintering behavior of mixed ash was discussed. The prediction models and methods of melting characteristics, viscosity temperature and slagging characteristics of mixed ash are also summarized. Finally, the paper puts forward the future research directions of ash slag from co-gasification of agroforestry waste biomass and coal.
Abstract(71) HTML(35) PDF 1289KB(14)
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The co-thermochemical conversion of coal and biomass can contribute to the low carbonization of current fossil energy system. In this work, the bituminous and lignocellulosic biomass were selected to study the co-pyrolysis and co-gasification of coal and biomass, with the consideration of different hydrothermal carbonization (HTC) temperature and biomass blending ratio. The synergistic effect of co-pyrolysis and co-gasification was analyzed by using the thermogravimetric analyzer, and the H2 release property was investigated by the online mass spectrometer. The model-fitting method was adopted to analyze the overall kinetics during pyrolysis and gasification stage, respectively. The results showed that the synergistic effect of coal and biomass in co-gasification stage was much stronger than that in co-pyrolysis stage. The gasification synergy was enhanced with the biomass blending ratio, while the HTC pretreatment would weaken the synergy. The H2 production was inhibited during co-pyrolysis. The first-order reaction model can well describe the co-gasification process, while the n-order reaction model was suitable for the co-pyrolysis process. For the blends of raw or the slight HTC biomass and coal, the overall pyrolysis activation energy (Ea) was greater than that calculated by the weighted average, whereas the overall gasification Ea showed the opposite trend. For the blends of the severe HTC biomass and coal, the Ea of co-pyrolysis and co-gasification were both close to the weighted average value.
Abstract(74) HTML(11) PDF 2312KB(4)
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Composition and structure characteristics of fine slag (FS) and coarse slag (CS) discharged by Texaco gasifier with Zhundong coal as raw material were analyzed, and their thermochemical conversion properties were analyzed. Proximate and ultimate analyses showed that the contents of fixed carbon in coarse slag are 42.31% respectively, indicating that coarse slag can be used as raw material to realize its high-added utilization. Analysis with Fourier transform infare spectrometer (FT-IR) suggest that the absorption peak of Si-O in coarse slag and fine slag is stronger, and there is a small amount of aromatic structure in fine slag. Thermal decomposition behaviors in inert atmosphere showed that the maximum weight loss rate peak of coarse slag is located around 600 ℃, while the maximum weight loss rate peak of fine slag is transferred to about 620 ℃. Results of thermal decomposition in oxidization atmosphere showed that there are obvious weight loss rate peaks derived from the combustion of fixed carbon in the temperature range of 500−700 ℃. The weight loss profiles of fine slag and coarse slag in inert and oxidization atmosphere were fitted by Coast-Redfern method, and the kinetic parameters, including pyrolysis/combustion activation energy and correlation coefficient, were calculated. Results showed that the fitting effect is better as the reaction order selected as 3 at the intense pyrolysis section (560−640 ℃) for coarse slag in inert atmosphere, with correlation coefficient R2 of 0.99 and activation energy E of 38.85 kJ/mol. Similarly, in the intense pyrolysis stage (590−650 ℃) of fine slag, the fitting effect is better as the reaction order selected 3, with the correlation coefficient R2 of 0.97 and the activation energy E of 79.09 kJ/mol. In oxidization atmosphere, at the intense combustion stage of coarse slag (540−605 ℃) and fine slag (530−605 ℃), the fitting effect is better as n=1 for the both slags, with the activation energy E of 226.46 kJ/mol and 154.73 kJ/mol respectively.
Abstract(49) HTML(33) PDF 3325KB(5)
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In order to analyze the distribution and occurrence of lithium (Li) and gallium (Ga) in coal separately, the No.11 coal seam from the Antaibao mining district was collected as research object. The distribution of Li and Ga in different ash fractions, sulfur fractions, and coal column benches was discussed. The relationship between Li and Ga with other major elements in the micro-area was investigated by time-of-flight secondary ion mass spectrometer (TOF-SIMS) and scanning electron microscope with energy spectrum (SEM-EDS). The difference in the occurrence of Li and Ga, and the influencing factors were discussed. The results show that Li is enriched in high-ash coal, while Ga does not change significantly in coal samples in various ash and sulfur fractions. In the longitudinal seam, Li is enriched in the coal bench with sufficient supply of terrestrial source material, while Ga is more evenly distributed in the coal seam. In the in-situ regions, Li occurs only in aluminosilicates, while Ga can occur in kaolinite, boehmite, pyrite, chloride, and sylvite. The correlation coefficient between Li and stable element zirconium (Zr) for all samples is 0.894. Both are mainly derived from acidic magmatic rocks in the source area. Gallium is abundant in both high-ash coal and high-sulfur coal due to its transitional property as a lithophile and sulphophile element. Its mobility makes it tend to be uniformly distributed in the coal seam.
Abstract(29) HTML(24) PDF 2883KB(2)
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The effects of extra-aluminum species (Al(OH)2+and Al3+) on the properties of Brønsted acid sites (BAS) were studied using thiophene as the model probe and HFAU as model zeolite by using a periodic DFT study. It is found that the Lewis acid strength of Al3+ species is higher than that of Al(OH)2+ species, and the hydroxyl species Al(OH)2+ in both directions have similar charge properties, that is, similar acid strength. The results of electronic properties combined with deprotonation energies (DPE) showed that the BAS in 1-HFAU/Al(OH)2+, 2-HFAU/Al(OH)2+and HFAU/Al3+ zeolites have similar acid strength (1045 ± 11 kJ/mol). It can be concluded that the difference of hydroxyl direction and Lewis acid strength of Al(OH)2+and Al3+ species hardly affect the acid strength of BAS. By simulating the adsorption of thiophene, the adsorption energies and the changes of electronic properties and geometric structure during the adsorption process were obtained. The results show that thiophene in HFAU/Al3+ zeolite is easy to be adsorbed on Al3+ site, which is due to the strong Lewis acid strength of Al3+ adsorption site. The thiophene in HFAU/Al(OH)2+ zeolite would be preferentially adsorbed on the BAS rather than the Al(OH)2+ adsorption site. In addition, Al(OH)2+ species can exert a weak interaction (dispersion interaction) on thiophene adsorbed on BAS to promote the adsorption of thiophene. The adsorption modes depend on the structure of Al(OH)2+ species and the direction of hydroxyl groups. This work explored the intrinsic properties of host-HFAU zeolite (containing extra-framework aluminum species) and guest-thiophene molecule from an electronic-level, and revealed the synergistic mechanism between acid sites.
Abstract(45) HTML(28) PDF 11608KB(10)
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In consideration of the inferior performance of ZIF-67 derived Co3O4 catalyst in the low-temperature formaldehyde oxidation, manganese was utilized to modify Co3O4 catalyst. The results showed that the Mn-Co3O4 catalyst exhibited the superior HCHO oxidation activity and achieved 90% HCHO conversion at a WHSV of 60000 mL gcat−1 h−1 and inlet HCHO concentration of 98.16 mg/m3 at 118 ℃. XRD, Raman and BET results demonstrated that the Mn-Co3O4 catalyst possessed lower crystallinity, more defects and specific surface area, which was conducive to the adsorption of reactants and exposure of more active sites. XPS, H2-TPR and O2-TPD results indicated that the strong interaction between Mn and Co species prominently improved the low temperature reducibility and O2 activation performance of Mn-Co3O4 catalyst, which endowed it with more abundant Co3+ and surface-adsorbed oxygen species. Therefore, the Mn-Co3O4 catalyst exhibited superior HCHO oxidation performance. Based on in-situ DRIFTS results, dioxymethylene and formate species were recognized as the main reaction intermediates of HCHO oxidation over the Mn-Co3O4 catalyst.
Abstract(10) HTML(3) PDF 1348KB(0)
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A series of LaCoO3/MO2 catalysts were prepared by support different carriers (M = Zr, Ti, Ce) through the citric acid sol-gel method, and the catalytic oxidation performance of toluene and NO and critical mechanism were investigated. The results found that the LaCoO3/CeO2 catalyst with CeO2 as the carrier exhibited the best catalytic oxidation performance, the conversion rate of NO can reach 68% at 300 ℃ and t90 of toluene is 245 ℃.The physical and chemical properties and microstructure of the supported perovskite catalysts were characterized by BET, XRD, H2-TPR, XPS technologies. The results showed that the supported perovskite has a larger specific surface area, Meanwhile, the supported perovskite catalyst has more active lattice oxygen and better redox performance. Moreover, the interaction between Co and Ce ions existed in the contact interface of LaCoO3 and the carrier CeO2, which was conducive to the formation of oxygen vacancies, thus providing more active sites for the reaction. The reaction mechanism was further explored by in-situ DRIFTs. NO oxidation on LaCoO3/CeO2 catalyst followed the Langmuir-Hinshelwood mechanism, and toluene oxidation followed the Mars-van Krevelen mechanism.
Abstract(19) HTML(33) PDF 2733KB(3)
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The dehydrogenation of propane was carried out with propane containing different proportions of propylene, and the carbon deposition behavior of Pt-based catalyst under propene-rich condition was investigated. The results show that the presence of propylene in the raw material accelerates the rate of carbon deposition, shortening the time of dynamic equilibrium of carbon deposition on the support, and promoting the formation of carbon on the surface area of the active phase and the graphitization of carbon deposition. At the same time, the rich propylene in the raw material increased the amount of unsaturated aliphatic compounds, thus promoting the generation of aromatic carbon and graphitized carbon, but the catalyst structure was not destroyed. In the process of propane dehydrogenation, When the propylene content increased to 1.5 mol%, the carbon “peak I” appeared on the surface of the active phase, and the "peak II" moves to the high temperature region. When the alkene content increases by 3.0 mol%, peak I and peak II merge together, and the area of the entire peak increases significantly. When the carbon deposition exceeds 10.26 wt%, the degree of carbon deposition and graphitization of the catalyst becomes higher and higher. The increase of the propylene content accelerates the saturation process of the carbon holding capacity of the carrier. Under the same reaction time, the amount of carbon deposit increases.
Abstract(90) HTML(14) PDF 1260KB(16)
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The technology of alkylation of toluene with methanol to p-xylene has attracted much attention due to the high selectivity of p-xylene and low energy consumption in product separation unit. Twin HZSM-5 molecular sieve has the characteristics of large coverage proportion of zigzag channels on the surface and less aluminum distribution on the outer surface. It shows high selectivity for p-xylene in the alkylation of toluene and methanol. In this paper, Silicalite-1(S-1) was grown epitaxially on the surface of twin HZSM-5 molecular sieve by hydrothermal crystallization, and twin HZSM-5@Silicalite-1 core-shell catalyst was obtain. Compared with twin HZSM-5, HZSM-5@40Silicalite-1 core-shell catalyst showed excellent catalytic performance in toluene methanol alkylation. Under the reaction conditions of 470 ℃, 0.1 MPa and hydrogen atmosphere, the conversion of toluene is 8.5% and the selectivity of p-xylene is 98.4%. Then, the effect of solid-liquid mass ratio of nuclear HZSM-5 and silicalite-1 shell precursors on the growth of silicalite-1 crystal was further studied, and the effect of silicalite-1 on the catalytic performance of twin HZSM-5 was investigated. The pore structure and acid properties of core-shell materials were studied in detail by SEM, XRD, XRF, liquid static adsorption, N2 adsorption desorption, NH3-TPD and Py-FTIR.
Abstract(81) HTML(53) PDF 1246KB(19)
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In the process of gasification for different size of coal particles, there are remarkable differences in the cracking mode, behavior of volatile removal and coke-slag interaction. These differences lead to the discrepancies in structural characteristics and reaction behavior for fine slag. Therefore, it is considered that the study on relationship between structure, properties and size distribution of fine slag from entrained flow gasification could provide vital guidance for analyzing the formation mechanism of fine slag and optimizing the size of coal particles for gasification. For this purpose, the fine slag from Ningdong typical GSP technology in Ningxia Province was selected as a raw material. After drying, crushing and sieving, three kinds of samples with size of ＜0.125, 0.125–0.250 and ＞0.250 mm were prepared, they are called small, medium and large size samples respectively. The Nitrogen adsorption, XRD, Raman spectroscopy and TGA were applied to clarify the physicochemical structure and combustion reactivity of fine slag. It is found that there are huge differences whether in the composition, structure or reactivity of the fine slag in different size. Precisely, the three types of samples account for 22%, 46%, and 32% respectively. And all the fine slag contains a large number of spherical particles and irregular particles. The slag in the middle size, which has most content of residual carbon (19%) and lowest graphitization degree (30%), shows the slightest gasification degree. And it also present the largest specific surface area (87.8 m2/g). In addition, the slag in middle size always presented the optimal combustibility index regardless of the heating rate, while the above properties of large size particles was completely opposite. Apparently, coal gasified sufficiently tends to form fine slag in large particle size, while coal gasified insufficiently is more likely to form slag in middle particle size. To some degree, all these findings mentioned above could supply a certain basis to the study of gasification process. Meanwhile, the medium-sized fine slag has the most content in fine slag, and it with low gasification degree and large content of carbon and large specific surface area and porosity so it still has a certain potential utilization value, which provides ideas for the treatment and disposal of the fine slag.
Abstract(67) HTML(15) PDF 415KB(4)
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As ammonia slip becomes more serious with the traditional deNOx application, ammonia-free technologies have received more and more attention recently. Cu-K bimetal loaded activated carbon catalysts were prepared by equivalent-volume impregnation method for the direct reduction of NO and showed good NO reduction performance in a wide temperature range under temperature-programmed surface reactions (TPSRs) conditions in aerobic and anaerobic environments. The catalysts were characterized by BET, SEM, XRD, XPS, H2-TPR, Raman and FT-IR techniques and the NO reduction mechanism was analyzed. Experimental results show that the active functional groups formed on the surface of activated carbon are the important intermediate products and play a key role in the reduction reaction. The presence of O2 greatly promotes the formation of the intermediate, C(O) (Oxygen-containing functional groups on the carbon surface), leading to the increase reduction rate of NO. The bimetallic oxides catalysts are obviously effective to directly reduce NO. When the ratio of copper: potassium is 2∶1, the NO reduction efficiency is about 90% at 300 °C. The catalytic activity mainly depends on the redox cycle of CuO/Cu2O, and the potassium inhibits the agglomeration of copper on the surface of carbon materials and enhances the catalytic reactivity of Cu.
Abstract(44) HTML(15) PDF 1288KB(1)
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The activation of C−H bonds of CH4 is a key step for the conversion of methane to chemical commodities. Loading Ni onto ZrO2 is regarded as a relatively efficient way to harness the beneficial electronic property and the fine dispersion of the Ni catalyst for CH4 dissociation. Herein we demonstrate the crucial role of Ni13 catalyst supported on ZrO2 for the dissociation of CH4. The density functional theory (DFT) results show that the ZrO2 supported Ni13 stabilizes all species better and facilitates CH4 activation. The stepwise dehydrogenations of CH4 on Ni13-ZrO2(111) exhibits longer C−H bond lengths of ISs , lower Ea, and smaller displacements between the detaching H and the remaining CHx fragment in TSs . In addition, they are also thermodynamically more feasible. However, without the ZrO2 support on Ni13, the opposite results are obtained. Consequently, the ZrO2 modified Ni13 is more superior to the original Ni13 in CH4 dehydrogenation. The electronic analysis combining DFT calculations confirmed that the larger overlap between C 2p and Ni 3d, and the electron transfer of Ni→C cause the weaker C 2p−H 1s hybridization. In addition, the reduction of electron transfer of H→C leads to a stronger interaction between Ni and C along with a weak C−H bond. Hence, the ZrO2 support serves as the d-band electron reservoir at Ni13 and it is benefit to the activation of C−H bonds in CH4 dehydrogenation.
Abstract(98) HTML(39) PDF 19992KB(14)
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Titanium subgroup nanometallic oxides (TiO2, ZrO2 and HfO2), prepared via supercritical method, were combined with ZSM-5 and quartz to obtain bifunctional catalysts (Ti/HZ, Zr/HZ, Hf/HZ) and metal oxide catalysts (Ti/Si, Zr/Si, Hf/Si) respectively. The effect of crystal structure, surface oxygen vacancy and syngas adsorption of metal oxides on the catalytic CO hydrogenation was investigated. The results show that the bifunctional catalysts could directly catalyze the syngas to aromatics. The oxygen vacancy concentration, oxygen electron properties and the H/C ratios (the adsorption ratio of CO to H2) of the metal oxides synergistically determine the type of intermediates on the metal oxide surface. The CHxO* species generated on the surface of ZrO2 is beneficial for Zr/HZ catalyst to obtain higher aromatic selectivity (71.15%), while CH3* on TiO2 and HfO2 leads to higher CH4 selectivity for Ti/HZ and Hf/HZ catalysts. The results of this research could provide a valuable reference for design of syngas aromatization catalyst.
Abstract(68) HTML(44) PDF 2440KB(16)
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The conversion of CO2, an abundant carbon resource, into high value-added chemicals or liquid fuels is an attractive way to mitigate carbon emissions, which is also a sustainable approach for the cyclic utilization of carbon resources. However, the selective activation and controllable conversion of CO2 is challenging because of the inertness of CO2 and high C–C coupling barrier. In recent years, some obvious breakthroughs on CO2 hydrogenation to high value-added chemicals or liquid fuels have been made by construction of a tandem catalytic system. For the tandem catalysis, the matching of Fe-based catalyst or metal oxides and zeolites, the assembly between the two active sites, the pore structure and acidity of the zeolites, as well as the reaction conditions and atmosphere all have important effects on the product distribution. Herein, the critical factors affecting the CO2 activation and conversion and the formation of the target products, as well as the stability over the tandem catalysts are summarized. Finally, an outlook are provided.
Abstract(63) HTML(48) PDF 1128KB(5)
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High-temperature coal tar foaming phenolic resins and phenolic foams were prepared by partially displacing petroleum-based phenol. High-temperature coal tar and the phenolic foams were analyzed with gas chromatograph/mass spectrometer and infrared spectroscopy. Morphology and performance of the phenolic foams including compression strength, slag rate, thermal stability, flame resistance, and thermal insulation were characterized with optical microscope, thermogravimeter, limited oxygen index instrument, and thermal conductometer. The results show that compression strength of the phenolic foams slightly decreased, while slag rate reduced, indicating the enhancement of toughness. Moreover, the phenolic foams possess good thermal stability, flame resistance, and thermal insulation with maximum limited oxygen index of 36.1% and minimum thermal conductivity of 0.034 W/(m·K) when the substitution rate is 10%−15%. The aforementioned results suggest that high-temperature coal tar can be used to partially substitute phenol to prepare phenolic foams with good performance, which could provide a new route for high value-added utilization of high temperature coal tar.
Abstract(53) HTML(15) PDF 1315KB(5)
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The way of CO dissociation, as a crucial step in the Fischer-Tropsch (F-T) synthesis process, has been a subject of intense debate in literature. In order to understand the F-T synthesis reaction behavior of cobalt catalysts with different crystal planes, the CO dissociation behavior over three cobalt catalysts with different crystal facets during F-T reaction was investigated by excluding the influence of support, promoter and particle size. The catalysts were characterized by temperature programmed desorption (TPD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), in-situ Raman and Chemical Transient Kinetics (CTK). The results show that CO on the Co(10-11) is activated by direct dissociation, among which small amount of carbonaceous species generated by CO dissociation forms carbon depositing on the catalyst surface under F-T reaction condition, and a large amount of carbonaceous species are hydrogenated to CHx species. The CO on the Co(0001) crystal surface is activated predominantly by hydrogen-assisted dissociation, a large fraction of CO is dissociated into carbon deposition and a tiny fraction of CO is hydrogenated into CHx. CO is directly dissociated on the Co(11-20) plane. The weak dissociation of CO on this catalyst results in a trace amount of carbon deposition, and a trace amount of CHx intermediate in the presence of hydrogen.
Abstract(32) HTML(24) PDF 4260KB(5)
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Gasification fine slag is a kind of solid waste with high carbon content produced in coal gasification process. The residual carbon obtained by carbon ash separation is a potential carbon source for preparing high quality carbon materials. In this study, the carbon residue after flotation of fine gasification slag was used as the precursor to prepare N-doped carbon-based electrocatalysts through high temperature activation. Combined with the characterization of Raman spectroscopy, XPS and SEM, the influence of activator ratio and nitrogen source on the physical and chemical structure of the catalyst was explored. The intrinsic relationship between activation formula and oxygen reduction performance of catalyst was revealed. The feasibility of preparing carbon-based electrocatalysts with gasification fine slag as raw material was verified. The results demonstrate that the oxygen reduction catalytic performance of carbon materials increases first and then decreases with the increase of the proportion of KOH. The optimal catalytic performance was achieved when the mass ratio of carbon residue to KOH was 1:4. In addition, melamine has stronger nitrogen doping effect as a nitrogen source than NH4Cl, making the initial potential of CKN6-143 up to 0.87 V (vs. RHE), the limiting current density is 4.95 mA/cm2, and the average electron transfer number is 3.82, indicating that CKN6-143 has good electrocatalytic performance. The results provide a possibility for preparing oxygen reduction catalyst with gasification fine slag.
Abstract(57) HTML(76) PDF 1370KB(5)
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In order to study the pyrolysis and combustion characteristics of different fibers, the kinetics of six kinds of plant fibers (coniferous, broadleaf, bamboo, flax, grass and cotton) in N2 and air atmosphere were studied by non-isothermal thermogravimetric (TG) method using Friedman method. The results showed that the fiber has different pyrolysis and combustion characteristic parameters, which are related to its own structural composition. In the process of pyrolysis and combustion of fibers, the initial volatilization temperature (Ts), terminal decomposition temperature (Th), DTG peak temperature (Tmax), fixed carbon combustion peak temperature, maximum mass loss rate, pyrolysis character index (P) and combustion character index (S) increased with the increase of heating rates; In N2 atmosphere, Tmax of the flax fiber and bamboo fiber was shown to be the highest and lowest among all fibers, respectively, and Ts of cotton fiber was the largest; Grass fiber had the smallest maximum pyrolysis mass loss rate (−(dm/dt)max), pyrolysis index (P), combustion index (S); Between the conversion of 0.05−0.85, the average apparent activation energy (E) of broadleaf fiber and bamboo fiber was the smallest (173.30 kJ/mol) and highest (201.10 kJ/mol), respectively. In air atmosphere, Tmax of all fibers in the pyrolysis process was lower than that in N2. The apparent activation energy (Ea) of fiber pyrolysis in air atmosphere was shown to be lower than that in N2 when the conversion was between 5% and 65%.
Abstract(36) HTML(8) PDF 1059KB(3)
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Carbon assisted water electrolysis for hydrogen production usually add carbon sources(such as coal and biomass) into anode cell directly to form carbon slurry. This route always suffer from low current density due to the high mass transfer resistance between carbon particles and anode. The Coal-based formcoke sacrificial anode was preparaed by co-forming and co-pyrolysis of coal, alkali-activated biomass and conductive graphite, and formcoke sacrificial anode was used in carbon assisted hydrogen production by water electrolysis. The efficiency of carbon assisted hydrogen production could be significantly improved at high current density (50mA/cm2). The water electrolysis performance of formcoke sacrificial anode and its microstructure evolution were studied. Results showed the current density of formcoke sacrificial anode were 87 times higher than that of Pt anode at 1.23(V vs. RHE), and the Tafel slopes also reduced by 41% compaired to that of Pt anode. The H2 formation rate of formcoke sacrificial anode was 2.75 times than that of Pt anode at 50 mA/cm2, while the potential of formcoke sacrificial anode was about 85% of Pt anode. The SEM、TGA、BET、FT-IR and XPS results showed that the sacrificial anode itself were oxidized during water electrolysis. Specifically the carboxyl C=O bond was oxidized to CO2, and the content of C–O bond increased significantly. This research provide a new insight and reference for carbon assisted water electrolysis for hydrogen production.
Abstract(45) HTML(46) PDF 1567KB(14)
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With the residual carbon in coal hydrogasification semicoke as both reducing agent and dielectric component, Ni/carbon-based composite materials for microwave absorption were prepared. The synthesis process mainly involved loading of Ni species via an impregnation of nickel nitrate solution and then an in-situ carbothermic reduction. The effects of Ni load on the microstructure and properties as well as the related mechanism were studied. The experimental results showed that the electromagnetic parameters could be readily regulated by changing the Ni load, which occurred as a result of the accompanied changes in carbon content, graphitization degree, as well as the number of interfaces and defects. Hence, a good impedance matching can be easily achieved. At a carbothermal reduction temperature of 700 ℃, the composite with 20 wt.% Ni load showed the best microwave absorption performance. For a coating thickness of 2.5 mm, the minimum reflection loss was −42.6 dB and the corresponding effective bandwidth was 4.1 GHz; while the effective bandwidth could be up to 5.6 GHz under 2 mm coating thickness. The dominant microwave absorption mechanism was the dielectric loss, which mainly derived from the conduction loss due to graphite carbon and the polarization relaxation losses because of the existence of interfaces and defects.
Abstract(40) HTML(8) PDF 1435KB(6)
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Using cerium nitrate as the source material and urea as the precipitant, nanometer CeO2 carrier was prepared by hydrothermal method, and the microstructure of CeO2 carrier was controlled by changing the hydrothermal reaction temperature. Then the CuO/CeO2 catalytic material was prepared by loading CuO on the CeO2 carrier and evaluated in methanol steam reforming for hydrogen production. Based on the characterization data of low temperature Nitrogen adsorption, XRD, H2-TPR and XPS, the effects of hydrothermal reaction temperature on the microstructure of CeO2, the structure of CuO/CeO2 catalytic material and the performance of methanol steam reforming were investigated. The results showed that the nanometer CeO2 support prepared at 180 ℃ has a cubic fluorite structure. After loading CuO onto the CeO2, the obtained CuO/CeO2 catalyst exhibited better catalytic activity due to its stronger Cu-Ce interaction, lower reduction temperature of Cu species in the surface, and more oxygen vacancies on the surface of the catalyst. When the reaction temperature is 280 ℃, the molar ratio of water to alcohol (W/M) is 1.2, and the space velocity of methanol vapor gas (GHSV) is 800 h− 1, the methanol conversion rate can reach 91%.
Abstract(43) HTML(32) PDF 1182KB(2)
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Raw coals and washery products were collected from two coal washing plants of Ningwu coal field, Shanxi, China. The migration behaviors of sulfur (S) and arsenic (As) during coal washing process were investigated by the microwave digestion method together with hydride generation - atomic fluorescence spectrometry. Based on the checked mass balance of As, a sequential-chemical-extraction method was used to explore the dependence of speciation transformation and release characteristics between S and As during the combustion process of raw coal, cleaned coal, coal gangue, middling coal, or coal slime. The results show that 20%−28% of S and As in raw coal are migrated to cleaned coal, and 46%−61% of them to gangue. Pearson correlation coefficient identifies that the inorganic minerals in samples control the migration behavior of S and As. Compared with the elements in raw coal, the proportions of organic S and As in cleaned coal is increased to 30%−50%, while the inorganic S and As in coal gangue account for more than 90%, which indicates that the dependence between the species of S and As in raw coal and its washery products. The relatively large amount of organic S and As in cleaned coal can be obviously released together with water and volatile matters below 500 ℃, while inorganic bonded As and S in gangue is mainly released during the decomposition process of pyrite, sulfate and other inorganic minerals between 500 ℃ and 1000 ℃, which shows the consistency of S and As release characteristics during combustion of raw coal or washery product. The release rates of S and As from cleaned coal are the fastest among all samples and the corresponding maximum release ratios are 80%−95% at 300 s and 60%−75% at 200 s, respectively, whilst their release rates from gangue are the slowest and As reaches the maximum release ratio of 40%−45% at 300 s but S doesn’t get to the maximum release ratio even at 600 s. The release rates of S and As from middling coal or raw coal are between them from cleaned coal and gangue. The different release rates of S and As during sample combustion are mainly depended on their speciation distributions in nature.
2022, 50(4): 1-6.
Abstract(36) HTML(9) PDF 2717KB(7)
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2022, 50(4): 385-395.   doi: 10.1016/S1872-5813(21)60164-0
Abstract(165) HTML(40) PDF 1112KB(35)
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Pyrolysis atmosphere has significant effect on yield and composition of coal tar. A pyrolysis and gasification integrated reactor in laboratory was used to investigate effects of gasification syngas on yield and composition of coal tar. The results show that tar yield of Naomaohu coal reaches the maximum at 600 ℃, and gasification syngas (G-gas) is more beneficial to improve the tar yield at low temperature (550–600 ℃). Especially, 550 ℃ tar yield increases by 4.4% compared with that under N2. With the introduction of G-gas, the yield of tar obtained at high temperature (650–800 ℃) decreases, but the quality of tar obtained at 650–700 ℃ is improved obviously due to the increase of light components. The cracking reaction of aliphatic hydrocarbons and oxygen-containing compounds in volatiles from pyrolysis at 550 and 600 ℃ is intensified by G-gas, thus substituted benzene and naphthalene compounds in coal tar increase. For the volatiles obtained above 650 ℃, the secondary cracking reaction of phenolic compounds is enhanced with the introduction of G-gas, which results in a decrease of phenolic compounds in tar. G-gas is also favorable for the secondary cracking reaction of polycyclic aromatic hydrocarbons in volatiles from pyrolysis at 800 ℃, but more favorable for generation of which in the tar obtained below 700 ℃.
2022, 50(4): 396-407.   doi: 10.1016/S1872-5813(21)60178-0
Abstract(96) HTML(37) PDF 1418KB(24)
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Ultrasonic assisted extraction residue (ER) from Naomaohu lignite (NL) was taken as the research object. ER was subjected to methanolysis at 300 ℃, and the effect of KOH was investigated. Composition of the two alcoholysis products, MP (without KOH) and MPKOH (with KOH) was analyzed by chromatograph/mass spectrometer (GC-MS). Benzyl benzoate (BB) and phenyl acetate (PA) were selected as model compounds (MER) for ER, and the alcoholysis products (BBP, BBPKOH, PAP and PAPKOH) were obtained. Results showed that the yield of MPKOH was 93.39%, while that of MP was only 5.25%, indicating that the addition of KOH greatly improved the yield of alcoholysis product. MP consisted of phenols, esters and alkanes with the relative contents of 17.92%, 34.83% and 5.98%, respectively, while the contents of the above three compounds in MPKOH were 34.8%, 10.17% and 8.71% respectively, indicating that transesterification or ester reduction reaction occurred in the alcoholysis process with the addition of KOH accompanied by alkylation reaction. Analysis of alcoholysis products of model compounds showed that methyl benzoate and benzyl alcohol were predominant in BBP, while methyl benzoate disappeared in BBPKOH, and the relative content of benzyl alcohol accounted for 91.85%; phenols were only detected in PAP, and the relative content of phenol was 87.97%. Whereas, the content of methyl substituted anisole and phenol accounted for the largest share in PAPKOH with the contents of 85.64%. Alcoholysis process of the two model compounds showed that, without KOH, transesterification or ester reduction reaction was occurred in the alcoholysis process. And the addition of KOH not only accelerated the above reaction, but also strengthened the alkylation reaction between the subsequent products and methanol.
2022, 50(4): 408-417.   doi: 10.19906/j.cnki.JFCT.2021084
Abstract(67) HTML(25) PDF 1506KB(5)
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In this paper, three-dimensional hierarchical porous carbons (HPCs) were prepared using coal tar pitch as raw material and α-Fe2O3 as template combined with KOH activation. The as-prepared HPC-3 showed large specific surface area (2003 m2/g), which was due to the synergistic effect of the occupation of α-Fe2O3 (certain mesopores and macropores) and KOH activation (abundant micropores). And the assembled electric double layer capacitor by HPC-3 exhibited the largest specific capacitance (295 F/g) and superior cycling stability (specific capacitance retention of 97.8% after 10000 cycles) in 6 mol/L KOH electrolyte. Meanwhile, the high working voltage (3.6 V) and energy density (60.0 (W·h)/kg) were obtained when it was applied to EMIMBF4 electrolyte.
2022, 50(4): 418-427.   doi: 10.1016/S1872-5813(21)60176-7
Abstract(104) HTML(24) PDF 899KB(6)
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To synthesize simple and efficient catalysts and their application in catalytic conversion of biomass platform compounds to prepare high value-added chemicals has always been the focus of researchers. In this paper, a catalyst composed of iron, manganese, copper and Schiff base ligand derived from amantadine salicylaldehyde was in-situ constructed to catalyze the selective oxidation of 5-hydroxymethylfurfural (HMF) to prepare 5-formyl-2-furancarboxylic acid (FFCA). The ligands and complexes were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and single crystal diffraction, and the reaction conditions such as oxidation reaction time, reaction temperature, molar ratio of MnCl2·4H2O to ligand, oxidant and catalyst dosage, etc, were optimized. Under the optimized conditions, 100% conversion of HMF and the FFCA with a yield of 52.1% can be obtained. Finally, on the basis of the reaction results, the HMF oxidation reaction process catalyzed by Mn metal complexes was analyzed.
2022, 50(4): 428-435.   doi: 10.19906/j.cnki.JFCT.2021087
Abstract(134) HTML(57) PDF 1164KB(26)
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Four typical lignins: alkali lignin, lignosulfonate, hydrolyzed lignin and G-type lignin, were selected to study their gasification weight loss characteristics, kinetic mechanism and product characteristics on a thermogravimetric analyzer (TGA) and fixed bed experiments, in order to reveal the influence of lignin sources on their gasification characteristics. The results showed that the homogeneous model fit the gasification reaction process well. Alkali lignin had the highest pyrolytic activity, reacted at lower temperature, and had the lowest activation energy. However, the structure of pyrolytic coke was dense and the gasification reactivity was poor. G-lignin had similar gasification characteristics with alkali lignin. Lignosulfonate and hydrolyzed lignin had two pyrolysis stages, and their coke gasification reactivities were high. For products characteristics, H2 and CO were the main gas products. Alkali lignin had the H2 yield as high as 55 mmol/g, the highest carbon conversion rate (87%), and the minimum residual coke. However, hydrolyzed lignin and G-lignin had lower gas production, but tar and solid residue were relatively more, which was mainly related to the inorganic mineral content and composition.
2022, 50(4): 436-445.   doi: 10.19906/j.cnki.JFCT.2021091
Abstract(97) HTML(9) PDF 908KB(23)
Abstract:

Fischer-Tropsch synthesis (FTS) is a promising route to produce various olefins and fine chemicals from non-petroleum carbon sources that can be used to produce synthesis gas, such as coal, natural gas and biomass. Cobalt-based catalysts have gained more attention in FTS for the academic research and industrial applications, owing to their excellent catalytic properties such as low water-gas-shift activity, great Fischer-Tropsch reaction activity and high chain growth probability. The structure of the microscopic active site and the surface adsorption of the cobalt-based catalyst during the Fischer-Tropsch progress have an effect on the product distribution and catalytic performance. In this review, we summarized some advancements in the development of cobalt-based F-T catalysts focusing on the effects of particle size, crystal phase, crystal plane and microscopic active site, with emphasis on the research from the types, surface adsorption behavior and characterization techniques of microscopic active site. Some suggestions for the development of cobalt-based F-T catalysts in the future are also given.

2022, 50(4): 446-455.   doi: 10.1016/S1872-5813(21)60174-3
Abstract(103) HTML(25) PDF 2466KB(21)
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Z-scheme photocatalyst holds great promise in photocatalytic H2 evolution. In this work, a ternary Au-OVs-BiOBr-P25 Z-scheme photocatalyst with oxygen vacancies was successfully prepared, in which Au nanoparticles were used as the electron mediators to introduce into BiOBr and P25. The photocatalytic activity of this ternary photocatalyst was evaluated by overall water splitting. The H2 evolution rate of Au-OVs-BiOBr-P25 achieves an amazing value of 384 μmol/(g·h) under UV-vis irradiation. UV-vis DRS and transient photocurrent spectra revealed that the enhanced photocatalytic activity of Au-OVs-BiOBr-P25 was mainly attributed to its widened photo-response range and effective carrier separation. Furthermore, the photocatalytic mechanism was systematically studied by EPR and Photoelectrochemical measurements, which indicated that the overall water splitting occurred through the two-electron pathway. This result will provide us new ideas for developing more efficient photocatalysts for photocatalytic H2 evolution.
2022, 50(4): 456-463.   doi: 10.1016/S1872-5813(21)60170-6
Abstract(171) HTML(69) PDF 1299KB(9)
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Solvothermal synthesis technique is an effective method to create composite materials. In this paper, a series of TiO2@MIL-101(Cr) were prepared by the solvothermal method for photocatalytic denitrification of pyridine in fuel under visible light irradiation. The products were characterized by XRD, FT-IR, SEM, TEM, BET, DRS and ESR. The result shows that 20%TiO2@MIL-101(Cr) has high catalytic activity, the pyridine removal efficiency reaches values as high as 70% after irradiation for 240 min. Finally, we obtained the possible mechanism of photocatalytic denitrification according to the HPLC-MS spectrometry results analysis.
2022, 50(4): 464-473.   doi: 10.19906/j.cnki.JFCT.2021086
Abstract(149) HTML(55) PDF 1429KB(15)
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Direct and selective conversion of methane to methanol under mild conditions still faces grand challenges. In this study, Co3O4/WO3 nanocomposite catalysts were synthesized by facile hydrothermal method, combining with surface impregnation process. The structural composition and micro morphology of Co3O4/WO3 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-visible absorption spectrum. The catalytic performance of Co3O4/WO3 on the conversion of methane to methanol was investigated under visible light illumination at room temperature. The results show that incorporating Co3O4 can remarkably improve the photocatalytic performance of methane conversion. The optimal catalyst 3.0% Co3O4/WO3 exhibits a methane conversion of 2041 μmol/g after visible light irradiation for 2 h, and the according methanol productivity and selectivity reach 1194 μmol/g and 58.5%, which are 4.03 and 2.39 times of single WO3 respectively. This performance is superior to most reported heterogeneous photocatalysts for methane conversion, meanwhile possessing excellent cyclic stability. Combining the results of transient photocurrent and electron paramagnetic resonance (EPR) with the catalytic activity, the intrinsic mechanism of enhanced methane conversion via introducing Co3O4 is revealed, which is of theoretical significance to design light-driven catalysts for methane conversion to methanol.
2016, 44(7): 777-783.
[Abstract](230) [FullText HTML](115) [PDF 2169KB](6)

2016, 44(4): 385-393.
[Abstract](203) [FullText HTML](143) [PDF 1138KB](11)

2016, 44(3): 263-272.
[Abstract](122) [FullText HTML](111) [PDF 1275KB](6)

2016, 44(7): 801-814.
[Abstract](288) [FullText HTML](201) [PDF 8665KB](23)

2016, 44(3): 279-286.
[Abstract](186) [FullText HTML](130) [PDF 12189KB](4)

2016, 44(11): 1388-1393.
[Abstract](191) [FullText HTML](128) [PDF 780KB](4)

2018, 46(2): 179-188.
[Abstract](127) [FullText HTML](69) [PDF 7028KB](7)

2016, 44(6): 732-737.
[Abstract](152) [FullText HTML](89) [PDF 2776KB](5)

2016, 44(9): 1034-1042.
[Abstract](217) [FullText HTML](123) [PDF 809KB](2)

2017, 45(1): 113-122.
[Abstract](179) [FullText HTML](114) [PDF 1085KB](4)

2013, 41(08): 1003-1009.
[Abstract](2118) [PDF 13334KB](13)
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](1563) [PDF 1335KB](15)
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.