Abstract: In order to clarify the effect of microwave field combined with peracetic acid (PAA) on the removal of organic sulfur in coal, four demineralized coals including Shanxi Linfeng (LF), Ningxia Ningdong (ND), Shanxi Lingshi (LS) and Henan Luoyang (LY) coal were selected, and three sulfur-containing model compounds including benzyl mercaptan (BM), benzo(b) thiophene (BT) and diphenyl sulfoxide (DS) were used as well. Each test, the microwave with the power of 100 W irradiated coal for 1-5 min combined with PAA. The change of sulfur form in the solid phase was analyzed by X-ray photoelectron spectroscopy (XPS). The concentration of SO42- in the liquid phase after desulfurization was analyzed by ion chromatography (IC), and the change of sulfur form in the extract was analyzed by gas chromatography/mass spectrometry (GC/MS). The results show that the higher the organic sulfur content, the greater the desulfurization rate. The maximum desulfurization rates of LY and LS are as high as 55.06% and 45.78%, respectively, and the maximum desulfurization rates of ND and LF are 31.24% and 28.21%, respectively. It is found that the organic sulfur as mercaptan in coal is easier to remove than that as thiophene and sulfoxide, and the sulfur form gradually transforms to a high valence state during desulfurization. The sulfur-containing bond is broken in the microwave field and the sulfur can be oxidized to SO42- by PAA finally.
Abstract: The influence of H2O on the adsorption of SO2 on CaO (001) surface was investigated by density functional theory (DFT). The results indicate that H2O can have an effect on the adsorption geometries for SO2 on the CaO (001) surface. When SO2 is adsorbed to the CaO surface near a water group of different forms (viz., -H2O, -H, -OH and -H & -OH), the H group makes the adsorption energy 90 kJ/mol higher with the sulfur p-orbital shifting downward, whereas other groups have little effect on the adsorption energy. When SO2 is adsorbs to the -OH surface and -H & -OH surface, bisulfite-like structures are formed, with lower adsorption energies and tending to form more stable structures as intermediates. When SO2 adsorbs to the -H2O surface, bisulfite-like structure is formed and the H2O group decomposes to Ca(OH)2 like-structure on the CaO surface; the new H groups mainly bond the bisulfite and make adsorption energy 45 kJ/mol higher.
Abstract: The effect of carbonization degree on pore structure and microstructure of walnut shell chars was studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The combustion characteristics of raw material and walnut shell chars were analyzed using a thermogravimetry coupled with differential scanning calorimeter (TG-DSC). The results show that the appropriate degree of carbonization (volatile content is 6%-15%) leads to the disorderly crystallization of turbostratic and the increase of defects in the carbonaceous microcrystalline structure, which causes a relatively flourishing pore structure and an increase of specific surface. Pyrolysis char at temperature of 500℃ has the maximum specific surface area of 374.60 m2/g, while walnut shell char prepared at 600℃ has the optimal combustion characteristics with the combustion characteristics index of 7.16×106, which indicate that the appropriate carbonization degree of char could reduce the volatile content and increase the higher calorific value of char during combustion process. Moreover, the developed pore structure can increase the contact area between char and air, leading to the accelerated combustion rate of char.
Abstract: The characteristics of high temperature rapid pyrolysis of oil slurry were studied by using a rapid pyrolysis device of high-frequency furnace. The effects of pyrolysis temperature and nitrogen flow rate on the compositions and yields of gas and solid phase products were investigated. The results show that the temperature is the key factor to affect the yields of gas phase products. The gas phase products are mainly methane, hydrogen and ethylene. Higher temperature can increase the yields of hydrogen and methane, while the yield of ethylene is affected by the secondary reaction at high temperature and decreased gradually after reaching the maximum at 800℃. The yields of ethane and propylene are lower, and gradually decrease after reaching the maximum at 700℃ due to the secondary reaction. A small amount of acetylene is formed when the temperature is higher than 800℃ and the yield of acetylene will be increased by increasing the temperature. Meanwhile, increasing the nitrogen flow rate can reduce the partial pressure of methane and hydrogen and shorten the residence time of ethylene and propylene in the high temperature area, leading to an increase in the yield of gas phase products. The yield of carbon deposition increases rapidly with the increase of temperature, while the increase of nitrogen flow rate could weaken the secondary reaction and reduce the yield of carbon deposition.
Abstract: A C9H10O2-0.5ZnCl2/Al2O3 catalyst was successfully prepared by immobilizing phenylpropionic acid-zinc chloride(C9H10O2-0.5ZnCl2) double acid deep eutectic solvent on Al2O3, and analyzed by XRD, FT-IR, SEM, EDS and N2 adsorption-desorption. The removal activity for aromatic sulfides in model oil using C9H10O2-0.5ZnCl2/Al2O3 as catalysis and H2O2 as oxidant and the effect of some reaction parameters such as temperature, catalyst dosage, O/S molar ratio and different sulfide types on the desulfurization activity of catalyst were investigated. The experimental results show that with the model oil of 5 mL, the catalyst dosage of 0.2 g and the O/S molar ratio of 8, at temperature of 60℃and reaction time of 180 min, the removal rate of DBT can reach to 99.2%. In addition, the catalyst can be recycled up to 6 times with a little decrease in catalytic activity for the ODS process. The catalysis-oxidation desulfurization mechanism of C9H10O2-0.5ZnCl2/Al2O3 was also explored.
Abstract: The mesoporous MCM-41 molecular sieve and heteroatom (Zn, Ba, and Ce) containing mesoporous MCM-41 molecular sieves were synthesized and characterized by X-ray diffraction (XRD), FT-infrared spectroscopy (FT-IR) and N2 sorption; their performance in the adsorption denitrification of quinoline in model diesel oil was investigated. The results indicate that all the synthesized molecular sieves take typical mesoporous structure and heteroatoms are successfully incorporated into the molecular sieves framework. An 8T cluster model for the MCM-41 molecular sieves was built by using the Materials Studio software; the simulated XRD spectrum is basically consistent with the experimental spectrum, proving the accuracy of cluster model. The adsorption of quinoline on the heteroatom-containing mesoporous MCM-41 molecular sieves were then simulated and the adsorption energy and the distance between the adsorbed molecule and the adsorption center (d(N-M)) were calculated. The results suggest that the adsorption denitrification performance of various molecular sieves follows the order of Zn-MCM-41 > Ce-MCM-41 > Ba-MCM-41 > MCM-41; that is, Zn-MCM-41 exhibits the best adsorption denitrification performance, with the highest adsorption energy and shortest distance between the adsorption molecule and the adsorption center. Moreover, the adsorption time has a significant influence on the denitrification efficiency, whereas the effect of adsorption temperature is relatively minor; the optimal adsorption times for Zn-MCM-41, Ba-MCM-41 and Ce-MCM-41 are 40, 10 and 30 min, respectively, whereas the optimal adsorption temperatures for three molecular sieves are 40, 30 and 40℃, respectively.
Abstract: The Ni-P amorphous alloy was synthesized by chemical reduction, modified by adding element Co, and characterized by XRD, SEM, XPS and DSC. The hydrodeoxygenation (HDO) performance of the amorphous alloy was investigated by hydrodeoxygenation of vanillin to 2-methoxy-4-methylphenol (MMP). It is shown that the synergy between Ni and Co not only contributes to the reduction of Ni, increases the number of active centers of the catalyst, but also improves the dispersion, disorder and thermal stability of the amorphous alloy. Under the optimized reaction conditions:nCo/(nCo + nNi)=0.08 (molar ratio), H2 partial pressure of 2.0 MPa, reaction temperature of 150℃, reaction time of 180 min, catalyst dosage of 0.05 g, vanillin conversion and the MMP selectivity can reach 100% and 82.7%, respectively. After 5 cycles of the catalyst, the conversion of vanillin remains 100% and the selectivity of MMP decreases to 68.7%.
Abstract: Three kinds of porous catalysts CuO-ZnO/SBA-15 (CZ/SBA-15), CuO-ZnO-MnO2/SBA-15 (CZM/SBA-15) and CuO-ZnO-ZrO2/SBA-15 (CZZ/SBA-15) were synthesized by impregnation method with a siliceous framework mesoporous molecular sieve SBA-15. The performance of all catalysts for catalytic hydrogenation of CO2 to methanol was evaluated on a fixed bed reactor, combined with N2 adsorption-desorption (BET), X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), temperature programmed desorption (H2-TPD, CO2-TPD), N2O titration, X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM). The results show that the introduction of metal oxide in the catalyst changes the pore size and specific surface area of the SBA-15 molecular sieve support. The CuO-ZnO-MnO2/SBA-15 and CuO-ZnO-ZrO2/SBA-15 have high copper dispersion (DCu%), large specific surface area (SCu), small surface CuO particle size, and easy to be reduced. Compared with the Mn-O cluster, the Zr-O cluster enhances the basic site and improves the methanol selectivity. In addition, CuO-ZnO-ZrO2/SBA-15 has the highest oxygen vacancy concentration and better catalytic activity among three catalysts. The methanol selectivity of CuO-ZnO-ZrO2/SBA-15 is 25.02%, which is 28% and 136.9% higher than those of CuO-ZnO/SBA-15 and CuO-ZnO-MnO2/SBA-15, respectively.
Abstract: A series of ZSM-5 zeolites were prepared by changing the NaOH content, and their catalytic performance on the vapor-phase carbonylation of dimethoxymethane (DMM) to synthesize methyl methoxyacetate (MMAc) was investigated detailedly. The results indicate that the ZSM-5 zeolite prepared under the 0.81% NaOH content shows the best catalytic performance. Various characterization results, including BET, 27Al NMR, NH3-TPD and Py-FTIR, illustrate that medium-strong Brønsted acid sites and mesoporous volume are the chief factors in promoting carbonylation of DMM over ZSM-5 zeolite, which can be effectively regulated by changing NaOH content. The increase of medium-strong Brønsted acid sites can improve DMM conversion by providing more active acid sites; the introduction of mesoporous can increase MMAc selectivity by shortening the product diffusion path, weakening steric constraint of pore walls and suppressing parts of side reactions. Density functional theory was further carried out to study the interaction between DMM and ZSM-5 zeolite. The calculated results find that intermediate species ZOCH2OCH3 is formed firstly during DMM decomposition. Based on this, a possible formation mechanism of MMAc was then proposed.
Abstract: Pd/Al2O3 catalysts modified by different amount of magnesium were fabricated for catalytic combustion of methane (CCM). After the introduction of different amount of magnesium, Al2O3, MgAl2O4-like mixed oxide and Mg(Al)Ox solid solution were formed. Owing to the formation of distinguished supports, the supported Pd species, i.e. metallic Pd, PdOx and support-Pd oxide complex were formed, and they were quite different in relative content and Pd↔PdO transformation ability. It was found that PdOx was active at low temperature, while metallic Pd particles and support-Pd oxide complex were active at high reaction temperature. The one with Mg/Al mole ratio of 1:3 was the most easily in Pd↔PdO transformation, demonstrating the best catalytic activity towards CCM reaction.
Abstract: Three boron nitride (BN) supported iron catalysts were prepared by the incipient-wetness impregnation method and characterized by XRD, TEM, FT-IR, and H2-TPR; their phase structure, morphology, reduction behavior and performance in the F-T synthesis were investigated. The results indicate that the addition of Cu promoter has little influence on the phase structure of BN support, whereas the addition of sodium borate can improve the crystallinity of BN support. Although the change in the catalyst morphology by introducing Cu and sodium borate is very small, the addition of Cu and sodium borate can decrease the reduction temperature of the BN-supported iron-based catalysts. For F-T synthesis under 340℃, 2 MPa, GHSV=1500 h-1 and n(H2)/n(CO)=2, the conversions of CO over Fe/BN, Fe/BNM and Fe-Cu/BN are 12.3%, 36.2% and 31.6%, respectively and the corresponding selectivities to CH4 are 57.9%, 26.8% and 44.7%, respectively. Fe-Cu/BN and Fe/BNM exhibit higher activity than Fe/BN, suggesting that adding promoter and improving the interaction between support and active component can both enhance the activity of boron nitride supported iron catalysts in F-T synthesis, which may give a clue to the design of highly active BN-supported iron catalysts.
Abstract: M/CuO/CeO2 (M=Cr, Zn, Y, La) catalyst was prepared by sequential impregnation method. The catalysts were characterized by XRF, XRD, BET, H2-TPR and XPS. The effects of different promoters on the structure and properties of CuO/CeO2 catalysts were investigated.The results show that the doping of promoters mainly affects the dispersion of CuO, the reduction properties of the catalyst, the interaction between CuO and CeO2, and the oxygen hole content on the surface of the catalyst. After doping additives Cr and Zn, improving the dispersion of CuO on catalysts, and the interaction between CuO and CeO2 strengthens, the surface oxygen holes increase, which in turn increases the catalytic activity. After doping the additives Y and La, decreasing the dispersion of CuO on catalysts, the interaction between CuO and CeO2 is weakened, and the surface oxygen holes are reduced, thus the catalytic activity is reduced. Among them, the catalyst doped with promoter Cr has better catalytic activity. When the reaction conditions are 260℃, n(CH3OH):n(H2O)=1:1.2 and the space velocity of methanol vapor gas is 1760 h-1, the final conversion can reach 100%, the CO content in reforming tail gas is 0.15%. Compared with CuO/CeO2 catalyst, the conversion rate is increased by 10%, and the CO content in reforming tail gas is reduced by 0.34%.
Abstract: A series of manganese-zirconium composite oxides were prepared by citric acid complexing method and characterized by XRD, H2-TPR, XPS and SEM; their performance in the catalytic reduction of NO by CO was investigated. The results show that Mn3O4 is the main phase for MnOx in the Mn-Zr composite oxide; an increase in the Zr content can promote the dispersion of Mn3O4 and reduce the average grain size of Mn3O4. Mn may exist in the form of Mn2+, Mn3+ and Mn4+ ions; the content of (Mn3+ + Mn4+) and the quantity of surface adsorbed oxygen (OA) increase after the addition of Cu and Ce, which is beneficial to enhancing the catalytic activity. The pristine Mn-Zr-O composite shows a relatively low activity in the catalytic reduction of NO by CO; after adding Cu, the Mn-Cu-Zr-O composite exhibits much higher activity than Mn-Zr-O; moreover, the activity of Mn-Cu-Ce-Zr-O composite is even enhanced by adding Ce. For the catalytic reduction of NO by CO over the Mn-Cu-Ce-Zr-O composite at 350℃ and with a space velocity of 18000 h-1, the CO conversion and NO conversion are 89.17% and 91.70%, respectively.
Abstract: A series of Y-Ce-Mn/ZSM-5 catalysts (Y=Co, Cr, Cu, La, Zr) were prepared by impregnation method. Combined with the results of the NH3-SCR activity test, the optimal activity temperature window and maximum denitration efficiency of various catalysts were obtained. The catalysts were characterized by XRD, TEM, H2-TPR, NH3-TPD and in situ DRIFTS. Through the characterization and denitration test, it was shown that the maximum denitration efficiency of all modified catalysts except Cr modified one was higher than 98%, and Cu-Ce-Mn/ZSM-5 showed the best performance among the catalysts, whose catalytic conversion at 375℃ was 99.22%. This is attributed to the highly dispersed surface metal oxide species, more surface sites with weak acidity and more species with high reducibility.
Abstract: In the solvothermal process of ZrO(NO3)2·2H2O-CO(NH2)2-CH3OH system, methanol can act as both solvent and a reactant. Due to the lack of water, methanol is directly involved in the hydrolysis-condensation reaction of zirconium salt, through the nucleophilic substitution between its methoxy groups and Zr4+ as well as the coordination as a molecular state, to form inorganic polymers with[ZrOz(OH)p(OCH3)q·rCH3OH]n structure. At the same time, the low solubility of methanol to the polymers strongly inhibits the Ostwald ripening process, thus hindering the crystallization of solvothermal products and also reducing the probability of the thermodynamically supported structural rearrangement. Urea competes with zirconium salt for water in the system and the hydroxyl groups on the skeleton of zirconium species by its hydrolysis reaction, which not only leads to an increase in the amount of Zr-O-Zr bonds in polymers and then a further decrease in the probability of structural rearrangement of the solvothermal products, but also an increase in the content of methoxy group in solvothermal products. When calcined at 400℃, the solvothermal products containing a large amount of methoxy groups transformed into C-doped zirconia. Carbon doping, together with the solvent effect, stabilized the tetragonal phase of zirconia. The tetragonal phase in C-doped zirconia showed comparatively high thermal stability during calcination in air and at the medium temperature range of 500-600℃. Increasing the calcination temperature to 700℃, the free carbon species on the surface of particles was completely removed by oxidation, and the C dissolved in the lattice was also partially removed, resulting in some tetragonal phases lost stability and turned into monoclinic phases.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
