Abstract: The effect of humic acid, an important component of lignite, on the water content in Shengli lignite was studied. The content of oxygen containing functional groups of humic acid in Shengli lignite was determined. The isothermal adsorption and desorption curves of the lignite, brown humic acid and the residual coal were analyzed. Further the primary and secondary site adsorption of the lignite, brown humic acid and the residual coal were studied. The results show that 2/5 carboxyl and 1/5 hydroxyl in Shengli lignite are provided by humic acid. The pore size and pore volume of brown humic acid are smaller than those of the lignite. So brown humic acid is unfavorable for the formation of water clusters. The humic acid is adverse to equilibrium adsorption of water for Shengli lignite.
Abstract: The effects of K2CO3 and atmospheres on sulfur distribution and forms during pressurized coal pyrolysis were investigated in a lab-scale reactor. The results show that K2CO3 increases the sulfur remained in char by capturing H2S during coal pyrolysis. The surface of the coal char is activated in the presence of K2CO3, and then the nascent sulfur releasing from the pyrite is captured by the organic matrix in coal to form new organic sulfur. Hydrogen shows positive effects on removal of pyrite and organic sulfur, and the released H2S is partly fixed in char in the form of K2S when K2CO3 was added. The decomposition of pyrite is enhanced in H2O atmosphere. Meanwhile, K2S in char can not exist due to effect of water vapour, so the sulfur remained in char is notably reduced. The catalytic property of K2CO3 on char gasification is not changed after pyrolysis in two-stage catalytic coal gasifier.
Abstract: The catalytic effect of calcium component on steam gasification of Shengli lignite char was studied. Demineralized coal samples were loaded with calcium oxide and pyrolyzed at 1 100℃ (Ca-J). Ca-J+ was prepared from Ca-J treated by hydrochloric acid. The char samples were characterized by BET, SEM-EDS, XRD, FT-IR and XPS. The steam gasification of the char samples was performed in a micro fixed bed reactor. The possible catalytic active micro structure was discussed and proposed. The results show that carbon conversion and reactivity index of Ca-J and Ca-J+ samples during steam gasification were substantially similar, but much higher than those of demineralized char samples (SL+-J). Ca (CH3COO)2 and Ca-OOR, two calcium species are present in Ca-J+ sample determined by XPS. Chemical analysis and SEM-EDS prove that calcium content of Ca-J+ decreases by more than 97% than that of Ca-J sample. XRD analysis indicates free inorganic mineral (CaS, CaO) is removed by hydrochloric acid. FT-IR spectra show C=O, C-O peaks present in Ca-J and Ca-J+ samples. So it is postulated that "R-O-Ca-O-R'" (R and R' are aliphatic and aromatic structures, respectively) is the catalyst active microstructure during char steam gasification.
Abstract: Co-firing of municipal RDF and coal gangue in existing coal gangue power station is a potential treatment way of municipal solid waste and coal gangue. The co-combustion characteristic of municipal solid waste (MSW) and coal gangue was investigated by thermogravimetric analyzer. The HCl emission in co-combustion of coal gangue with PVC, NaCl and MSW were also studied using a high-temperature tube furnace combustion system. The results show that the combustion characteristic of coal gangue can be improved obviously with blending of MSW, especially for devolatilization and ignition characteristics. In consideration of combustion characteristics, the MSW blending ratio of 20% is suggested. When the blending ratio of PVC or NaCl is low, the existence of coal gangue can inhibit the release of HCl in PVC while promote the release of HCl in NaCl. As the increase of blending ratio, the effect decreases gradually. In co-combustion of MSW and coal gangue, the release ratio and concentration of HCl is increased. When the MSW blending ratio is 10%, the HCl emission concentration is 56.22 mg/m3 which exceeds the national standard. Hence, the dechlorination measurement should be considered.
Abstract: The variation of chemical composition of thermal bitumen during Huadian oil shale pyrolysis was studied. Spent shale samples obtained by retorting oil shale at 300-550℃ were subjected to sequential Soxhlet extraction-acid pickling-Soxhlet extraction procedures to obtain free bitumen (FB), bitumen bound with carbonates (BB-1) and bitumen bound with silicates (BB-2). The bitumen samples were characterized by liquid chromatography fractionation, FT-IR and GC-MS. The results show that the total bitumen yield first increases and then decreases with increasing temperature from 300 to 550℃, and reached the maximum value of 4.63% at 400℃. Especially, the intense vaporization and decomposition of bitumen occurring at 400-450℃ causes a dramatic decrease in bitumen yield from 4.63% to 0.98%. Decarboxylation of aliphatic acids, decomposition of esters and cracking of long-chain alkanes take place at 350-450℃, which decreases the contents of acids and esters in FB and shortens the chain length of alkanes. The carboxylic acids derived from kerogen pyrolysis can react with carbonates to form carboxylates, leading to a high amount of aliphatic acids in 400℃ BB-1 (78.82%). The contents of oxygenated compounds (acids, esters and phenols) and alkanes of 400℃ BB-2 are 80.79% and 19.21%, respectively, due to the combination between oxygenated compounds and clay minerals, and the insertion of alkanes into the interlayer space of montmorillonite.
Abstract: The asphaltene was obtained from the low temperature coal tar heavy fraction by solvent precipitation with three kinds of solvents; n-pentane, n-pentane with 5% ethanol and n-pentane with 5% isopropanol. The properties such as structure parameters and hetero atom distribution were analyzed by 1H-NMR, 13C-NMR, FT-ICR MS, elemental analysis and average molecular weight determination (GPC). Some possible average molecular structures containing hetero atoms were constructed and discussed. The results show that after adding polar solvent, the yield of C5-asphaltene is significantly reduced, while the aromaticity and average molecule weight are enhanced. The average molecular structure of the C5-asphaltene exhibits shorter side-chains and higher condensation degree. Though the type of heteroatom compounds in the asphaltene is barely changed by the addition of polar solvents, the relative abundance of O3-O6 class species is increased. Meanwhile, some O1-O2 class species with low condensation degree are transferred into maltene, indicating that the mixed solvent has a larger solubility with these compounds.
Abstract: A series of NiWF (x)/γ-Al2O3 catalysts were prepared by adding different amounts of ammonium fluoride, and the effects of fluoride amount on the structure and physicochemical properties were investigated with X-ray diffraction, X-ray photoelectron spectroscopy, NH3-TPD and high resolution transmission electron mcroscopy (HRTEM) techniques and N2 sorption experiment. Their hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) catalytic performances were evaluated in a fix-bed reactor with low and middle-temperature coal tar obtained from Inner Mongolia as feedstock. Although fluoride amount has little effect on the pore diameter and pore volume of the catalysts, increase of the fluoride amount decreases the specific surface area. In addition, the sulfidation degree of the catalyst decreases with the fluoride amount when it is sulfided at 643 K for 6 h. Also, the numbers of strong acid sites and total amount acid sites change with increasing fluoride amount. They slightly increase at first, but then obviously decrease. HRTEM shows that WS2 slabs have a typical layered structure. The catalytic activity of NiWF (x)/γ-Al2O3 for HDN and HDS of coal tar shows a volcanic trend with the fluoride amount.
Abstract: A series of Li/MgO catalysts with different Li loadings were prepared by incipient wetness impregnation method and characterized by TG-DTA, N2 sorption and XRD; two modes for propane adsorption on Li/MgO were considered by calculation with Material Studio and the influence of Li loading on the catalytic performance of Li/MgO in the oxidative dehydrogenation of propane to olefins was investigated. The result indicated that with the increase of Li loading, the conversion of propane and the selectivity to C2H4, C2H6, CH4, COx increases at first, reaches the highest values at a Li loading of 3% and then decreases with further increasing the Li loading, whereas the selectivity to propene changes in an opposite trend. The adsorption and dehydrogenation of propane on Li/MgO surface are controlled by both thermodynamic and kinetic factors, whilst the dispersion of the active Li+O- sites is related to the loading of Li. Over the highly-dispersed active Li+O- sites, the dehydrogenation is thermodynamically controlled, which favors the formation of propene, whereas over the poorly-dispersed Li+O- sites, the reaction is dominated by the kinetic factor, leading to a high selectivity to ethene and other by-products.
Abstract: Sulfonated carbons with hierarchically ordered pores (SCHOP) were prepared by means of dual template self-assembly, carbonization, HF etching, and sulfonation. The effect of carbonization temperature on microstructure of the prepared carbons as well as the SCHOPs were surveyed at 500-700℃. Using fructose dehydration to 5-hydroxymethylfurfural as a probe reaction, catalytic performance of SCHOPs was examined. The results show that SCHOP-500 carbonized at 500℃ exhibits the highest catalytic activity. SEM and TEM characterization as well as N2 adsorption desorption show that all of the SCHOPs possess hierarchically ordered macropores and mesopores, but high carbonization temperature damages the regularity of carbon materials slightly. FT-IR, EDS and -SO3H determination confirm that sulfonic acid group could be successfully introduced to carbon materials by sulfonation. However, high carbonization temperature lowers aromaticity of the carbon materials, and as a result leading to low sulfonation degree. Under the catalysis of SCHOP-500, as high as 93.4% of 5-HMF yield with 96.1% fructose conversion rate is achieved after reacting at 130℃ for 20 min, indicating that SCHOP-500 is a highly effective and efficient solid acid catalyst.
Abstract: A series of Cu/ZnO catalysts were prepared by using co-precipitation method and their performance for the furfural gas phase hydrogenation to 2-methylfuran was investigated in a fixed bed reactor. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption desorption, H2 temperature programmed reduction (H2-TPR), scanning electron microscope (SEM) and NH3-temperature programmed desorption (NH3-TPD) techniques to analyze the roles of Cu0 and ZnO. The results showed that Cu0 was the active center for the furfural hydrogenation and the addition of ZnO in Cu catalysts can reduce the crystal size, enhance the surface area, improve the reduction and increase the surface acidity of the catalysts. When the molar ratio of Cu/Zn molar ratio is 1:2, Cu1Zn2 catalyst showed the highest selectivity to 2-methylfuran due to its suitable numbers of redox active centers and weak acidic sites. Under the atmospheric pressure, reaction temperature of 200℃, 4:1 molar ratio of hydrogen to furfural and furfural volume space velocity of 0.3 h-1, the conversion of furfural reached almost 100.0% with 93.6% selectivity to 2-methylfuran over Cu1Zn2 catalyst.
Abstract: The palm oil biodiesels with different ester alkyls were prepared through transesterification of palm oil with methanol, ethanol, isopropanol and isobutanol. The crystallization behavior and cold flow properties of the palm oil biodiesels were characterized by differential scanning calorimeter (DSC) and stress controlled rheometer; the effect of ester alkyl on certain important properties such as the oxidation stability, kinematic viscosity (40℃) and density (20℃) was then investigated. The results suggested that the palm oil biodiesels with larger ester alkyls exhibit lower crystal precipitation temperature and gelation point than those biodiesels with ester methyl; especially, the crystal precipitation temperature and gelation point for the palm oil biodiesel derived from isobutanol reach -2.57 and -8.09℃, respectively. An increase in the length of ester alkyl chain in alcohol moiety can significantly improve the cold flow properties of the palm oil biodiesels, by slightly prolonging the oxidation induction period and enhancing the oxidative stability. The palm oil biodiesels with different ester alkyls are also different in their kinematic viscosity and density; however, all these values can meet the requirement from the biodiesel standard of China.
Abstract: Generally, the process for synthesis of hierarchical-structured ZSM-5 zeolite is complex. Here, the polygonal three-dimensional ZSM-5 zeolite with hierarchical structure was hydrothermally synthesized by one-step synthesis method with dual templates. The effects of crystallization conditions and synthesis gel compositions, including crystallization temperature, crystallization time, Si/Al molar ratio, on the products were investigated for optimizing synthesis conditions. The X-ray diffraction (XRD), N2 adsorption-desorption experiment, Pyridine adsorption FT-IR (Py-FTIR), scanning electron microscopy (SEM) and transmission electron microscope (TEM) were used to characterize the crystalline structure, pore structure, surface acidity and crystal morphology of products. It was shown that the hierarchical-structured ZSM-5 zeolite can be synthesized under the following conditions: crystallization temperature of 160-180℃, crystallization time of 24-96 h, the SiO2/Al2O3/Na2O/CTAB/TPABr/H2O ratio of 1/x/0.4/0.05/0.12/280, (x: 50-240). The sample crystallized at 160℃ for 48 h with a synthesis gel having a Si/Al molar ratio of 50 had uniform cylindrical crystal morphology, high crystallinity and ordered mesoporous structure with a pore diameter of 3.60 nm. It contains both strong Brønsted and Lewis acid sites at 300℃, which contribute to its catalytic properties.
Abstract: HZSM-5 zeolites with different molar ratios of SiO2/Al2O3 were treated by different concentrations of tetrapropylammonium hydroxide (TPAOH) solution. HZSM-5 zeolites with micro-meso pores were synthesized. The results show that the treatment of HZSM-5 zeolite with different molar ratios of SiO2/Al2O3 by different concentrations of TPAOH could cause desilication. The pore diameter of mesopores increases with the increase of TPAOH concentration and SiO2/Al2O3 molar ratios. Meanwhile, the acidic properties were adjusted. HZSM-5 zeolites were treated by different concentrations of TPAOH solution, whose SiO2/Al2O3 molar ratios are 50, 80 and 150. HZSM-5 with SiO2/Al2O3 molar ratio of 50 is obviously better than others in the content of relative acid, L-acid, B-acid and the strength of weak acid. HZSM-5 (SiO2/Al2O3 molar ratios is 50) by the treatment of TPAOH in different contents is most preferable for thiophene alkylation.
Abstract: A novel hierarchical porous IM-5 (IM-5-K) was synthesized by using mesoporous silica KIT-6 as the silica sources. The physical properties and acidities of the samples were characterized by XRD, SEM, TEM, BET and NH3-TPD. Moreover, Mo-modified catalyst, Mo-IM-5-K was prepared for non-oxidative aromatization of methane. Compared with Mo-IM-5-C, the Mo-IM-5-K catalyst showed higher conversion of methane and yields of aromatics. In addition, Mo-IM-5-K exhibited better stability than Mo-IM-5-C. Different activities and stabilities of the catalysts may be due to their different structure properties and acidities. The existence of secondary mesoporous systems may influence the location and state of the active Mo species, simultaneously lead to easier access to the active sites for reactants and better diffusion of aromatic products, thus improvs the activities of the catalysts.
Abstract: With various zeolites such as β, ZSM-5 and USY as the support, a series of Mn-Ce catalysts were prepared by impregnation method and characterized by XRD, BET, NH3-TPD, H2-TPR and XPS; their catalytic performance in the NH3-SCR of NOx at low temperature was investigated. The results show that all these catalysts are highly active in the NH3-SCR reaction at low temperature; especially, over the Mn-Ce/USY catalyst, the conversion of NOx reaches 90% at 107℃. After loaded of manganese and cerium, the specific surface area and pore volume of supported catalysts are decreased. Amorphous MnOx as the active component and crystalline CeO2 are detected on the surface of ZSM-5 zeolite. The weak acid sites on the catalyst surface probably play an important role in the NH3-SCR at low temperature. Meanwhile, a high atomic ratio of Mn4+/Mn3+ and concentration of adsorbed oxygen may also promote the NH3-SCR reaction at low temperature.
Abstract: The promotion effect of Ce modification on V2O5-WO3/TiO2 for the selective catalytic reduction (SCR) of NOx with NH3 and the SO2 deactivation mechanism were investigated. Compared with V1W5Ti catalyst, the advantage of V1W5Ce6Ti catalyst shows a good catalytic activity. These catalysts were investigated by means of XRD, BET, FT-IR, TG-DSC and XPS. The results demonstrate that the active components of V and W are well-dispersed, while a small cluster of cubic CeO2 appears over the V1W5Ce8Ti catalyst. The sulfation of V1W5Ti under reactive conditions can generate NH4HSO4 and (NH4)2SO4 at 250℃. The Ce additive to V1W5Ti could provide stronger Brønsted acid sites and more chemisorbed oxygen. The deposited ammonium sulfate on V1W5Ce6Ti catalyst is much smaller than that on V1W5Ti because the cerium sulfates species on the surface of V1W5Ce6Ti is formed and the deposition of ammonium sulfate is inhibited, which can disrupt the redox cycle between Ce3+ and Ce4+ and break the V-O-Ce structure, causing the deactivation of V1W5Ce6Ti catalyst.
Abstract: A series of V2O5 doped Ti-Ce-pillared clays (V2O5/Ti-Ce-PILC) were prepared and characterized by XRD, nitrogen physisorption, FT-IR, XPS, H2-TPR, TG and NH3-TPD. The catalytic performance of V2O5/Ti-Ce-PILC in the selective oxidation of H2S was investigated in a fixed bed reactor. The results illustrated that 5%V2O5 doped Ti-Ce-pillared clays performs well at 180℃ in the selective oxidation of H2S, which can be ascribed to the interaction among V2O5, TiO2 and CeO2. CeO2 can enhance the catalyst thermostability and supply more lattice oxygen, which is of benefits to the redox of V2O5 and the decrease of reaction temperature. Meanwhile, the addition of TiO2 may promote the reoxidation of VOx and CeOx and reduce the sulfate coverage, which can then postpone the catalyst deactivation.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
