Abstract: In order to study effect of CaO content on the ash fusibility of high sodium coal, high sodium synthetic coal ash samples with different CaO content were prepared and ash fusion temperatures (AFTs) were measured. Thermodynamic database FactSage 7.0 was applied to simulate the ash melting process, and the mineral conversion was analyzed. The minerals' composition and surface morphology of synthetic coal ash samples were investigated by X-ray diffraction (XRD) and scanning electronic microscope (SEM). The results show that the AFTs drop first and rise later with the increase of CaO content. CaO addition influences the existence form and relative mass of both calcium-containing and sodium-containing minerals. At 1 000℃, the calcium-containing minerals transform from anorthite to andradite, wollastonite, gehlenite, rankinite and larnite in turn. The sodium-containing minerals transform from albite to nepheline. The results of binary phase diagram and analogous ternary phase diagram indicate that variation of liquidus temperature is consistent with the AFTs with increasing CaO content. When the CaO content is higher than 40%, the AFTs could be improved efficiently for the coal sample.
Abstract: To investigate the effect of water content in flue gas and moisture in coal on the greenhouse gas CO2 storage and coal spontaneous combustion when injecting power plant flue gas into goaf, the dry and wet coal structural models were established. The adsorption behavior of flue gas mixtures of CO2/O2/N2/H2O with different water contents by dry coal and wet coal with various moisture contents was simulated using Grand Canonical Monte Carlo method. The result shows that the competitive adsorption ability and capacity of CO2 in flue gas are the strongest, while the physical adsorption amount of O2 is the least. The H2O content in flue gas has little effect on the adsorption amount of CO2, N2 and O2. So the power plant flue gas can be directly injected into the goaf without drying. As the water content in the coal increases, the pore space is occupied by water, the Van der Waals force decreases, and the hydrogen bonding between H2O-H2O increases to provide additional adsorption sites. However, because the isosteric heat of H2O increases and the adsorption sites move toward a lower interaction region where the adsorption is stronger, a large amounts of water is adsorbed to form water clusters and compete the adsorption sites and space with CO2, O2, N2, leading to a decrease in gas adsorption amount by more than 50%. Therefore, the water content in goaf coal should be fully taken into account when the flue gas is injected.
Abstract: The reaction mechanism of homogeneous and char-catalyzed heterogeneous NO reduction with HCN were investigated by density functional theory (DFT) of quantum chemistry; the reaction kinetic parameters were determined according to classical transition state theory (TST). The results indicate that the activation energy of homogeneous NO reduction is 306 kJ/mol, much higher than that of heterogeneously catalytic reduction of NO; the later can be as low as 136 kJ/mol. Under the typical reburning temperature (1 400 K), the reaction rate of heterogeneous reduction of NO with HCN is slightly lower than that of heterogeneous reduction catalyzed by char; in comparison with the heterogeneous NO reduction by CO, the heterogeneous NO reduction by HCN over char is more likely to occur. The adsorption sequence of various components has a significant effect on the heterogeneous NO reduction by HCN; the reaction rate coefficient of NO adsorbed on char surface with HCN is 5.28×1010, which is an order larger than that of the surface adsorbed HCN with NO. Char exhibits a significant catalytic effect on the NO reduction with HCN; char provides surface reaction sites for NO reduction which can effectively activate the reaction gas.
Abstract: 12-tungstophosphoric acid (H3PW12O40, HPW) intercalated layered double hydroxides (LDHs) with various Mg/Al molar ratios were synthesized by an ion-exchange method. The samples were characterized by XRD, FT-IR, Raman, ICP-AES and TG-DSC. The acid strength and amount of acidic sites of catalysts were measured by Hammett indicator and n-butylamine titration technique. Furthermore, HPW intercalated LDHs were used as esterification catalysts for deacidification of crude oil and compared with their nitrate LDHs precursors. The relationship between the catalytic activity and the property of HPW intercalated LDHs was investigated. It is found that the catalytic activity of LDHs mainly depends on the acidity and the specific surface area. HPW intercalated LDHs exhibit a much higher catalytic activity than nitrate LDHs owing to the increased acidity and specific surface area. Due to the poorer acidity, the activity of nitrate LDHs is proportional to their specific surface area. The nitrate LDH with Mg/Al molar ratio of 4 exhibits the highest specific surface area and deacidification ratio. However, for highly acidic HPW intercalated LDHs, the amount of acidic sites dominates the catalytic activity and the HPW intercalated LDH with Mg/Al molar ratio of 2 has the highest acidity and esterification activity.
Abstract: A mild hydrogenation of simulated bio-oil was carried out in a fixed-bed reactor. Based on the experimental results, 300℃/4 MPa was chosen as an optimum condition for the mild hydrogenation, the simulated bio-oil was nearly completely converted. Besides, the liquid product selectivity achieved 85.0% and its (H/C)eff was significantly promoted from 1.266 to 1.554. The liquid composition was greatly improved and a notable decrease of phenols and acids contents was observed. In this case, the product activity was significantly enhanced and then the subsequent catalytic cracking was favored.
Abstract: With 1, 1-diphenylethene (DPE) as the polymerization inhibitor, the effects of DPE concentration (dosage) and reaction temperature on the active fragments transforming to liquefaction products during cellulose liquefaction in supercritical ethanol were investigated using an autoclave. As the DPE concentration increases, the yield of volatile compounds decreases by 25.4%, while the yield of bio-oil increases to 39.8%, and the cellulose conversion rate decreases gradually. With the increasing of reaction temperature, the cellulose conversion rate reaches to 85.5% sharply and the volatile compounds also increases fastly, but the maximum bio-oil yield drops to 34.6%. GC-MS analysis shows that ketones, esters, alkanes, alcohols, acids and the DPE derivatives are dominant platform chemicals in the bio-oil. A lot of active fragments (such as CH3CH2-, HO-, H-, CH3-, etc.) produced from cellulose pyrolysis in supercritical ethanol are trapped by a higher concentration of DPE to form DPE derivatives, which has a strong steric effect on the fragments transforming to platform chemicals. With the increasing of temperature, the enhanced pyrolysis of cellulose by ethanol radicals is more significant in comparison with the inhibition of DPE, resulting in an improvement in the content of platform chemicals.
Abstract: A novel hierarchically porous IM-5-H zeolite material was prepared through one-step crystallization route by means of adjusting the synthesis parameters without introducing any secondary template.The hierarchical IM-5-H zeolite is quite different from the conventional IM-5-C in morphology, textural and acidic properties.After loading Mo, the Mo-IM-5-H catalyst exhibits high activity and stability in non-oxidative aromatization of methane, with a methane conversion of 13.1% and aromatics yield of 7.5%, owing to the mesopores in the IM-5-H zeolite crystals.This work provides a simple way to synthesize hierarchical IM-5 zeolite and expands the application of micro-mesoporous composite material in methane dehydroaromatization.
Abstract: CoFe2O4 nanoarray catalysts were fabricated on iron foam by a controlled process involving the hydrothermal growth and calcinations of iron-doped cobalt carbonate hydroxide hydrate (CoFe-CHH) nanowires precursors.The crystalline phase, microstructure and component of CoFe2O4 nanoarrays were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES).The produced catalysts were used for Fischer-Tropsch synthesis and the nanoarray catalysts displayed a high CO conversion rate of 69% at 5L/(g·h) and a better performance than powder catalysts.
Abstract: The HZSM-5 synthesized with modifying by different contents of hemicellulose.The morphology, texture and acidity were characterized with XRD, SEM, N2 adsorption-desorption, NH3-TPD and Py-FTIR. Butene oligomerization over the modified HZSM-5 was tested. The results indicate that the HZSM-5 with the 1.6% hemicellulose exhibits the best activity and stability on the butene oligomerization reaction, the conversion can maintain about 80% after 140 h on stream, with the highest selectivities of the trimer, tetramer and diesel component in the products. These may be related with its high BET surface and mesoporous volume, and the strongest acidity.
Abstract: The effect of the number of crystal seeds on the physical and chemical properties and catalytic performance of the mordenite (MOR) zeolite was investigated using the transalkylation of toluene and trimethylbenzene as the probe reaction. The results show that the addition of seed crystals in the synthesis process will significantly affect the acidity, specific surface area and pore volume of the catalyst, thus affect the activity and stability of the catalyst. When the addition amount of crystal seeds is 8%, the MOR has the most B acid content, the maximum specific surface area and the pore volume, and the activity and stability of the catalyst are also the best. In addition, the mechanism of the transalkylation reaction of toluene and trimethylbenzene has been studied in detail. The results show that the transalkylation reaction in the MOR molecular sieve channels is carried out by the mechanism of bimolecular intermediates, and the intermediates, confirming the rationality of the mechanism of the bimolecular intermediates and deducing the possible reaction route.
Abstract: Cu-Fe-MgO/AlPO4-5 catalysts were prepared by impregnation method using AlPO4-5 molecular sieve as support to produce hydrogen through steam reforming of methanol. The catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR, CO2-TPD and NH3-TPD. The reaction results indicated that the addition of Fe could significantly increase the conversion of methanol, but the selectivity of dimethyl ether was also increased. The addition of MgO had obvious effects on the reduction of dimethyl ether formation, but the conversion of methanol could not be improved. The catalyst with Cu, Fe and MgO loadings of 15%, 6% and 1%, respectively showed a higher catalytic activity. Under the reaction conditions of 300℃, 1.1:1 of molar ratio of water to alcohol and 2.51 h-1 of mass space velocity, the conversion of methanol was 93.08%, the selectivity of carbon dioxide and hydrogen were 95.80% and 96.93% respectively and the selectivity of by-products of carbon monoxide and dimethyl ether were 1.70% and 2.51% respectively. According to the characterization results, Cu-Fe-MgO/AlPO4-5 contains weak acid and base sites, strong acid and base sites. It can be concluded that appropriate amount of MgO increases the amount of strong basic sites, reduces the strength of weak acidic sites, but had little effects on strong acidic sites.
Abstract: A series of SO42-/AC bifunctional catalysts, in which SO42- and AC acted as the acid sites and redox sites, respectively, are prepared by impregnation with H2SO4 and (NH4)2SO4 as precursors and active carbon as support; their catalytic performance in the direct oxidation of dimethyl ether (DME) to polyoxymethylene dimethyl ethers (DMMx) was investigated. The results show that the catalytic performance of SO42-/AC catalysts is significantly related to the precursor used. Over the 40%H2SO4/AC catalyst, the selectivity to DMM1-2 reaches 59.7%, with a DME conversion of 8.4%; in addition, there is no COx observed in the products. However, a large amount of COx by-product is formed over the 40%(NH4)2SO4/AC catalyst; meanwhile, the selectivity to DMM is only 2.7% and no DMM2 is formed. The XRD, N2 sorption, NH3-TPD and O2-TPD-MS characterization results illustrate that the suitable amount of weak acid sites and redox sites of the H2SO4/AC catalyst is beneficial to the formation of long chain DMMx from DME oxidation. The modification of AC with SO42- promotes the activation of O2 over the surface of AC support, whereas the introduction of H2SO4 improves the weak acid sites of the catalyst. On the contrary, the number of medium-strong acid sites of the catalyst is increased by modifying AC with (NH4)2SO4.
Abstract: The Cu/ZnO catalyst was prepared by the coprecipitation method, and the H-β zeolite was prepared by the hydrothermal synthesis method, and the bifunctional catalyst Cu/ZnO@H-β-P with core shell structure was prepared by the physical envelope method. The catalysts were used in the reactions of LPG preparation from syngas. The catalysts were characterized by the means of XRD, BET, NH3-TPD and SEM-EDS. The activity of the catalysts was evaluated by a continuous flow fixed bed reactor. The results show that the Cu/ZnO@H-β-P catalyst was the mesoporous material with core shell structure, and the acid intensity of H-β zeolite was changed, and the cascade reactions from methanol to dimethyl ether to LPG were promoted by core-shell synergy in the Cu/ZnO@H-β-P catalyst. The CO conversion and LPG selectivity were higher on the Cu/ZnO@H-β-P catalyst with core shell structure than those on the Mix-Cu/ZnO-H-β catalyst. The catalyst activity was affected by the reaction conditions of space velocity and reaction temperature. The best space velocity and reaction temperature were 2 400 h-1 and 350℃. The CO conversion and LPG selectivity achieved respectively 57.22% and 60.52% in the reaction of LPG preparation from syngas at the best reaction conditions using the Cu/ZnO@H-β-P catalyst.
Abstract: The nature and effect of coke formation on PtSn dehydrogenation catalyst were investigated by various technologies, such as HRTEM, XRD, FT-IR, Raman, 13C NMR, NH3-TPD, DTG and ultimate analysis. The deactivation process of the catalyst was also discussed. The results showed that the catalyst deactivation was mainly caused by deposited carbon, which covered active sites and blocked the pores of the catalyst. The diffraction peaks of the amorphous graphite carbon were observed in the XRD patterns of the fully deactivated catalyst. Furthermore, the degree of aromatization and graphitization of coke formed in the catalyst were enhanced. It was difficult to regenerate the deactivated catalyst through coke elimination. It is proposed that the carbon deposit proceeded on the Pt active site by propane deep dehydrogenation and the deposited carbon could transfer to the surface of the support. The coke precursor is probably C24H12 when the coke content was accumulated to a certain degree.
Abstract: ZrO2 doped with various concentrations of yttrium(0-5%) was prepared by a hydrothermal homogeneous co-precipitation method and CuO was then deposited on ZrO2 by a deposition-precipitation method to get the yttrium promoted CuO/ZrO2 catalyst; its performance in the water-gas shift reaction for producing hydrogen was then investigated. The results indicate that the catalytic activity of CuO/ZrO2 can be effectively improved by yttrium modification; over the yttrium promoted CuO/ZrO2 catalyst with an yttrium concentration of 2%, the CO conversion reaches 91.4% at 270℃, much higher than those over the conventional CuO/ZnO and CuO/CeO2 catalysts. The XRD, N2-physisorption, N2O titration, SEM and CO-TPR characterization results reveal that Y3+ is successfully incorporated into the lattice of ZrO2, which has a great influence on the structure and reducibility of the CuO/ZrO2 catalysts. Y3+ doping into ZrO2 introduces oxygen vacancies, improving the dispersion of CuO and increasing the proportion of catalytically active Cu-[O]-Zr species. In addition, the introduction of yttrium improves the monodispersity and modifies the texture properties of the CuO/ZrO2 catalysts. As a result, the superior activity of 2% yttrium promoted CuO/ZrO2 catalyst is probably attributed to the abundance of Cu-[O]-Zr species, high reducibility of Cu-[O]-Zr species and surface hydroxyl groups, high monodispersity and proper textural properties.
Abstract: A microbial fuel cell (MFC) was built with corn stalk hydrolysis solution as the anode substrate and activated sludge source bacteria as the anode microbes. The anode carbon felt (blank CC) was modified by various methods such as HNO3 acid treatment (HNO3/CC), chitosan modification (chitosan/CC) and layer-by-layer self-assembly (PDADMAC/α-Fe2O3/CC); the effect of anode modification on the performance of MFC in electricity generation was investigated. The results indicate that with blank CC, HNO3/CC, chitosan/CC and PDADMAC/α-Fe2O3/CC as the anode materials, the maximum electricity outputs of MFC are 248, 315, 452 and 522 mV, respectively, the maximum power densities are 54.6, 92.7, 203.8 and 248.1 mW/m2, respectively, and the COD removal rates are 82.21%, 81.46%, 82.53% and 86.44%, respectively. Moreover, PDADMAC/α-Fe2O3/CC exhibits the highest redox potential according to the CV curves and minimum polarization resistance (7 Ω) as determined by the EIS curves. As a result, the performance of MFC with four anodes follows the order of PDADMAC/α-Fe2O3/CC > chitosan/CC > HNO3/CC > blank CC.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
