Abstract: Eleven coking coals were used in this study and FT-IR and the caking index tests were carried out. The peak separation and quantitative calculation of FT-IR spectra were performed by using Peakfit Software and the relationship between caking property and typical functional groups of coal was investigated. The results showed that there was a close relationship between caking property and FT-IR spectra of coal, especially in the regions of 3 000-2 800 cm-1 and 3 700-3 000 cm-1. The component with aliphatic structure was a major determinant of coal caking property. Usually the shorter chain length or the higher branching degree of coal aliphatic structure was, the higher caking property will be. The caking property was codetermined by aliphatic structure and hydrogen bond (including-OH or-NH) and there was a synergic relationship between them. When the condensed degree of structural unit was low and the amount of bridge bonds was higher, the plastic mass based on structural unit with moderate molecular weight can be generated regardless of the coal molecule size. The most dominant sort of binding forces in coal was hydrogen bond. An associative structure even supermolecular structure, which was broken and changed into plastic mass during the state of metaplast, was formed when a number of hydrogen bonds were associated together. The existence of plastic mass was beneficial to the transformation of metaplast into semi-coke and further acquisition of well caking property.
Abstract: The Mn-SC and Mn/Ce-SC adsorbents were prepared by modification of semi-coke(SC) with manganese nitrate and cerium nitrate, and their mercury removal performance in simulated syngas was investigated in a lab-scale fix-bed reactor. Effect of cerium and manganese on the surface physical and chemical properties of semi-coke was characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that BET surface area, average pore size and total pore volume of Mn-SC are higher than those of SC, while Mn/Ce doping modification has adverse effect on the pore structure; MnxOy and CexOy exist in highly dispersive amorphous form on the surface of semi-coke. The mercury removal efficiency of Mn/Ce-SC is higher than that of Mn-SC and SC, and decreases with increase in adsorption temperature. Generally, the Mn/Ce-SC exhibits good mercury removal performance at elevated temperatures. With the presence of 1% of O2, oxidation and reduction reaction cycle could occur on the surface of Mn/Ce-SC, and oxygen in syngas is converted into lattice oxygen with high oxidation activity. Based on the Mars-Maessen mechanism, Hg0 could be oxidized to Hg2+ by lattice oxygen and then adsorbed. The mercury removal efficiency of Mn/Ce-SC maintains over 95% at 260 ℃.
Abstract: The charge performance of ash generated from co-combustion of different types of coals and biomass fuel (corn stalk) was studied using faraday-cup detector and electrical low pressure impactor (ELPI). The results show that the charge capacity of co-combustion ash rises a little with the increase of biomass in fuel mixture. The reason is that different types of co-combustion ash have different chemical compositions and structural features. This improves the relative dielectric constant, specific resistance and surface adsorptive ability, and thus promotes the charge performance of co-combustion ash. Although the addition of biomass in fuel mixture raises the charge capacity of co-combustion ash, particle size is still the main influence factor on its charge performance.
Abstract: The biomass coal-water slurries (BCWS) were prepared using Guizhou anthracite and distillers' grain with different proportions. The influence on slurry ability of BCWS with different type and addition of additives and distillers' grains blend proportion was studied. The results show that among naphthalene sulfonic additives (MF, NNO) and calcium lignosulphonate (LS) the dispersion effect of MF, exhibiting the best viscosity reduction effect when the addition is 0.5%, is better than that of NNO and LS. The anthracite slurry concentration is 70%, but the concentration of BCWS is 65.8% with stability of over 3 d when the distillers' grains blend proportion is 3%. BCWS belongs to Bingham plastic fluid. The bundle and vein structure of distillers' grains with vast hydrophilic oxygen-containing groups are the main reason of the increasing apparent viscosity, but could improve the stability of BCWS.
Abstract: With salicylic acid as hydroxyl radical (HO·) trap and carbon tetrachloride as hydrogen radical (H·) trap, the effects of HO· and H· radicals on the liquefaction of cornstalk cellulose in sub/supercritical ethanol was investigated in an autoclave. The results indicated that the concentration of HO· radical increases with the increase of salicylic acid amount added in the feed from 0 to 4 mL; meanwhile, the bio-oil yield is increased from 29.3% to 47.9%, whereas the residue yield is decreased from 26.7% to 24.3%. The activity of HO· increases with the increase of reaction temperature from 250 to 320 ℃; meanwhile, the bio-oil yield is increased from 35.9% to 58.2%, whereas the residue yield is reduced from 51.8% to 20.4%. On the other hand, the concentration of H· radical decreases with the increase of carbon tetrachloride from 0 to 2 mL; meanwhile, the bio-oil yield is decreased from 24.7% to 20.7%, whereas the residue yield is increased from 54.1% to 59.1%. The liquefaction of cellulose is enhanced within 30 min due to the increase of H· activity; after that, the bio-oil yield begins to decline due to the inhibition of H· activity by CCl4. Current results proved that ethanol can produce HO· and H· radicals under sub/supercritical state; the concentration and activity of HO· and H· radicals are dependent on the reaction conditions, which may determine the product yield and distribution for the liquefaction of cellulose in sub/supercritical ethanol.
Abstract: A magnetic core-shell CaO-MgO@CoFe2O4 solid base was prepared with oxalates as the precursor through a two-step method, which was used as the catalyst for the transesterification of soybean oil to biodiesel with methanol. The CaO-MgO@CoFe2O4 catalyst was characterized by magnetic hysteresis loop, X-ray diffraction (XRD), CO2-TPD and transmission electron microscopy (TEM); the effects of core-shell molar ratio, catalyst calcination temperature, reaction temperature, reaction time, methanol/oil molar ratio and catalyst amount on the yield of biodiesel were investigated. The results indicated that over the CaO-MgO@CoFe2O4 catalyst with a core-shell molar ratio of 1:6 and calcined at 700 ℃, the biodiesel yield reaches 97.1% after conducting the transesterification reaction at 65 ℃ for 3 h, when the methanol/oil mol ratio is 12 and the amount of catalyst is 1.0% by mass. The catalyst exhibits excellent reusability; the biodiesel yield remains above 90% after reusing for four cycles.
Abstract: The chlorinated and fluorinated zeolite catalysts were prepared by the impregnation of zeolites (H-ZSM-5, H-MOR or H-Y) using two halogen precursors (ammonium chloride and ammonium fluoride) in this study. The influence of ultrasonic irradiation was evaluated for optimizing both halogen precursors for production of dimethylether (DME) via methanol dehydration in a fixed bed reactor. The catalysts were characterized by SEM, XRD, BET and NH3-TPD. The reaction conditions were temperatures from 100 to 300 ℃ and a WHSV =15.9 h-1. All halogenated catalysts show higher catalytic activities at all reaction temperatures studied. However, the halogenated zeolite catalysts prepared under ultrasonic irradiation show higher performance for DME formation. The chlorinated zeolite catalysts show higher activity and selectivity for DME production than the respective fluorinated versions.
Abstract: CuO:ZnO:ZrO2=5:4:1 (molar ratio) catalysts were prepared with CaO doping of 0,1%, 2%, 4%, 8%, 16% (molar fraction) by cocurrent-flow co-precipitation. X-ray diffraction (XRD), thermal analysis(TG-DTG), Fourier infrared (FT-IR), N2 adsorption desorption (BET), X-ray photoelectron spectroscopy (XPS), hydrogen temperature programmed reduction (H2-TPR), CO2 temperature programmed desorption (CO2-TPD) and NH3 temperature programmed desorption (NH3-TPD) were used to characterize the catalysts. The catalyst activity was evaluated with a lab-made fixed bed reactor. Results show that CaO doping enhances Lewis acid and surface alkaline of the catalyst, increases the amount of high temperature carbonate in the catalysts, improves the thermal stability, reduces the CuO particle size, enhances the synergistic effect of Cu-Zn, increases the Cu specific surface area and the Cu dispersion. The catalyst activity is influenced by the surface acidity, the specific surface area of copper, the synergistic effect of Cu-Zn and the dispersion of copper. When the doping amount of CaO is 2%, the copper specific surface area is 79.3 m2/g, the dispersion degree of copper is 34.8%, the CO2 conversion is 19.01%, the selectivity of methanol is 24.55% and the yield of methanol is 0.044 g/(gcat·h), catalyst activity is the highest. With the amount of CaO increasing, the excessive CaO occupies the catalyst pore and covers the surface active sites, the Lewis acid and the surface alkaline of the catalysts become so strong that the effective contact of CuO and H2 is reduced, CO2 is difficult to desorb, resulting in decrease of catalytic activity. Therefore, the proper doping amount of CaO (2%) can promote the synthesis of methanol through CO2 hydrogenation.
Abstract: A series of K promoted K/MgFeZn-HTLcs catalysts with different Mg/Fe/Zn molar ratios were prepared by means of precipitation method and impregnation method for the direct synthesis of light olefins from CO hydrogenation. The samples were characterized by N2 adsorption-desorption SEM, TG, XRD, XPS and H2-TPR measurements. The results showed that the MgFeZn-HTLcs catalyst precursors have typical lamellar structure, larger specific surface area and average pore diameter compared with Fe/Zn catalyst. The BET surface area and the average pore diameter decreased after calcination and K promotion. The bulk composition of the calcined samples was mainly metal oxide and ferrite. Fe5C2, MgCO3 and ZnO were formed in K/MgFeZn-HTLcs catalysts after reaction. However, the main phase in K/2Fe-1Zn catalyst was stabilized in ZnFe2O4. During CO hydrogenation, the prepared samples showed high C2-4= selectivity and low C5+ weight fraction compared with that of K/2Fe-1Zn sample. The product distribution was greatly improved. Over the sample K/2Mg-2Fe-1Zn, an olefin to paraffin ratio of 5.15 and the C2-4= weight olefin content of 48.56% could be obtained.
Abstract: A complexes was produced using hexamethylenetetramine(HMT) as the complexing agent of ammonium molybdate, and β-Mo2C was prepared by a simple thermal decomposition of this complexes. And then Ni was introduced and the bimetallic carbide Ni3Mo3N/β-Mo2C was prepared. The as-prepared products were characterized by XRD, low-temperature nitrogen adsorption, SEM, HRTEM, element analysis (EA), and the performances of the prepared catalysts for methanation were investigated. The results showed that the bulk molybdenum carbide exhibited high conversion of CO (xCO), but xCO and selectivity of CH4 (sCH4) on β-Mo2C decreased from 75.93% and 36.79% to 67.41% and 33.54% within 100 h. Thus the catalytic activity was not stable and sCH4 was low. The addition of Ni markedly promoted the catalyst activity and stability, xCO and sCH4 on Ni3Mo3N/β-Mo2C increased from 83.15% and 46.64% to 92.51% and 57.23% within 100h, which should be attributed to the newly produced Ni3Mo3N after Ni addition.
Abstract: The characterization of a series of CoMo/Al2O3-SiO2 catalysts with different SiO2 contents were studied using in-situ FT-IR, Raman, UV-Vis and H2-TPR techniques. The results show that the increase of the silica component in CoMo/Al2O3-SiO2 catalysts can promote the transformation of octahedral molybdenum species into tetrahedral molybdenum species, and the higher SiO2 content can contribute to the transformation. Proper amount of silica component in the mixed supports can alter the interaction between the support and the active metals, resulting in higher hydrodesulfurization(HDS) activity of CoMo/Al2O3-SiO2 catalysts.
Abstract: Hβ-Al2O3 composite supports were prepared through mechanically mixing Al2O3 with hierarchically mesoporous Hβ zeolite obtained by desilication with NaOH solution; bifunctional NiWP/Hβ-Al2O3 catalysts were then obtained by impregnation method. The composite supports and NiWP/Hβ-Al2O3 catalysts were characterized by XRD, BET and NH3-TPD; the effect of Hβ addition on the catalytic performance of NiWP/Hβ-Al2O3 in diesel oil hydro-upgrading was investigated in a fixed bed reactor with fluid catalytic cracking (FCC) diesel as the feed. The results showed that by adding 15% Hβ in the Hβ-Al2O3 composite support, NiWP/Hβ-Al2O3 catalyst performs best in diesel oil hydro-upgrading; under 360 ℃, 8 MPa, volume space velocity of 1.0 h-1 and volumetric hydrogen/oil ratio of 800, the desulfurization degree reaches 99.77%, the density of FCC diesel oil is decreased from 0.927 to 0.837 g/cm3, while the cetane value is increased from 13.78 to 55.39.
Abstract: Noble metals are widely used as hydrogenation catalysts for refining and modifying fuel oil. However, their stability is still a problem. Thus, crystal transformation method was used here to encapsulate platinum (Pt) particles in sodalite through two steps. First, the sample was crystallized at 100 ℃ for 12 h. Then, it was further crystallized at 120 ℃ for 144 h, 130 ℃ for 96 h, 140 ℃ for 60 h, 150 ℃ for 42 h, or 160 ℃ for 30 h. The resultant solid (designated as Pt/SOD) shows high activity and excellent sulfur-tolerant performance in benzene hydrogenation. The crystalline phases were identified by X-ray diffraction technique. The hydrogen spillover effect of Pt/SOD and the spillover hydrogen acceptability of HZSM-5 were investigated with H2-TPD.
Abstract: PtCu/C membrane catalysts were prepared by ion beam sputtering (IBS) with moving bimetallic Pt and Cu targets; they were post-processed by vacuum annealing in combination with acid etching. High resolution transmission electron microscopy (HRTEM & STEM) and atomic force microscope (AFM) were employed to characterize the surface morphology of post-processed samples; the alloying degree of Pt and Cu was determined by the X-ray diffraction (XRD). Through cyclic voltammetry (CV) and linear sweep voltammetry (LSV), the electrochemical hydrogen evolution properties of the PtCu/C membrane catalysts were investigated. The results indicated that the PtCu/C membrane catalyst annealed at 400 ℃ and etched by HNO3 exhibits honeycomb nano-porous structure; the loading of Pt is reduced by about 8.77%, whereas the catalytic activity is enhanced by about 20.62%, in comparison compared with the original PtCu/C membrane catalyst.
Abstract: ZSM-5 was modified by metal M (M for Mg, Ni or Sr) using impregnation method first, then the micro-mesoporous composite molecular sieve of M-ZSM-5-SBA-15 was synthesized by post synthesis. The samples were characterized by means of XRD, N2 adsorption-desorption, FT-IR, NH3-TPD and Py-FTIR. The influence of silica alumina ratio of the HZSM-5 and different metals modification on alkylation performance were investigated. The results showed that the ZSM-5/SBA-15 composite molecular sieve with silica alumina ratio of 80 showed the best performance in alkylation. The introduction of Sr passivated strong Brnsted acid centers and reduced the ratio of Brnsted acid and Lewis acid of ZSM-5-SBA-15(80), resulting in good performance in alkylation with a toluene conversion of 30.15% and a p-xylene selectivity of 77.41%.
Abstract: The effect of arsenic on the performance of commercial V2O5-WO3/TiO2 catalyst for selective catalytic reduction (SCR) of NOx was investigated with the assistance of XRD, N2 sorption, NH3 chemisorption, FT-IR and XPS; an arsenic poisoning mechanism was proposed. The results illustrated that As2O3 in flue gas is a serious toxicant to the V2O5-WO3/TiO2 catalyst. As2O3 adsorbed on the catalyst are mostly oxidized to As2O5, which covers the catalyst surface and results in a decrease of surface area and active V sites; as a result, the adsorption of NH3 is then inhibited, which leads to the deactivation of the V2O5-WO3/TiO2 catalyst for SCR.
Abstract: The poisoning of a commercial selective catalytic reduction (SCR) catalysts by alkali (K) and alkaline earths (Ca) has been simulated in the laboratory. The techniques of N2 adsorption, scanning electronic microscopy, X-ray photoelectron spectroscopy, NH3-temperature program desorption, H2-temperature program reduction were used to identify the changes of physical chemical characteristics of the catalysts before and after the simulated poisoning. The results indicated that the poisoning of K and Ca did not damage the basic pore structure of the SCR catalyst, but decreased the BET surface area and pore volume. The poisoning by K and Ca changed the chemical valence state of V and decreased the reducibility of V. The poisoning by K and Ca decreased the amount of chemically adsorbed oxygen on the catalyst surface as well as acidity of the catalysts. The poisoning by K and Ca lowered the SCR activity of the catalysts and the poisoning by Ca was more serious than K.
Abstract: The growth characteristic of biomass-fired PM2.5 with vapor condensation was studied. A growth tube was employed to investigate the growth performance of PM2.5 at various temperatures of water, initial concentrations of particles, residence times and surfactants. The results show that the growth performance of PM2.5 from biomass combustion is better than that of coal-fired PM2.5 with vapor condensation. Furthermore, both the water temperature increase and the residence time delay benefit the growth of PM2.5. Unlike the growth of PM2.5 from coal combustion, the growth of small size of particles is seldom affected by the initial particles concentration. However, with a certain amount of surfactant addition, the particles can all grow up to 1 μm .
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
