Abstract: The behaviors of mineral matters in Shengli and Gaoping coal ash under reducing atmosphere at high temperatures were investigated by X-ray diffraction (XRD). The contents of crystalline minerals and amorphous matters were calculated using Siroquant software based on the XRD pattern of coal ash, and the chemical compositions of amorphous matters in coal ash at high temperatures were studied using the subtraction method. The results show that the content of crystalline minerals and amorphous matters in coal ash and the variation of chemical composition of amorphous matters in coal ash at different temperatures could be obtained using Siroquant and chemical analysis. The form of amorphous matters in coal ash varies with temperature. The amorphous matters in the coal ash exist in the form of non-crystalline oxides below 1100℃ and they transform to vitreous materials above 1200℃ because some crystalline minerals melt at high temperatures. The low Si/Al ratio of coal ash is beneficial to the formation of mullite at high temperature.
Abstract: The thermodynamic equilibrium calculation was conducted to estimate the beryllium conversion in the combustion process of coal, and the high temperature vacuum tube furnace was used to research the beryllium compounds reaction with other solid substances and the coal combustion experiments by adding sorbents. X-ray diffraction (XRD), X-ray fluorescence probe (XRF) and inductively coupled plasma-mass spectrometry (ICP-MS) were used to reveal the transformation behavior of beryllium during coal combustion. The results indicate that the beryllium only reacts with aluminum compounds and the reaction resultants are BeAl2O4 and BeAl6O10, the solid-solid reaction experiments are in agreement with thermodynamic calculation results, but the actual reaction temperature is about 1000℃, far above the thermodynamic calculation temperature 650℃. Because beryllium reacts with Al2O3 in combustion, the release rate of beryllium in the coal sample added with Al2O3 reduces greatly by up to 33%. Moreover, the inhibition of illite to beryllium release for coal combustion with addition of illite is weaker owing to a higher reaction temperature of illite with beryllium than that of Al2O3. Kaolinite, because its reaction temperature with beryllium is too high, has the lowest inhibition effect.
Abstract: The performance of Fe-Ni/ATP for catalytic lignite char gasification was investigated by one-step method in a small fixed-bed reactor. The catalyst Fe4Ni2/ATP4 shows an excellent catalysis for coal gasification and methanation at 650℃ and 2MPa with the methane selectivity of 24.75%, increasing by 58.76% compared to Fe4/ATP6. After five cycles, the catalyst still has a high stability with stable carbon conversion and space-time yield (STY) of CH4 production rate. The CaO that exists in the attapulgite carrier could enhance the gasification reaction. The Fe can react with water vapor to produce hydrogen significantly, which can promote coal char hydrogenation and CO methanation. When the active component Ni is introduced into the system, the reduction temperature of catalyst is reduced due to the formation of iron-nickel alloy, and the methanation activity of the prepared catalyst is increased further.
Abstract: Methane cracking was studied over a set of Xiaolongtan lignite chars in a fixed bed reactor at 1123K and atmospheric pressure with a mixture of CH4/N2 (1:4). The chars were obtained by pyrolysis of raw Xiaolongtan coal in nitrogen at 1173K for 30min in a fixed bed reactor. The main functional groups in coal char were hydroxyl group, carbonyl group and ether bond and so on, which can be protected by dipping the char into solutions of barium hydroxide, phenyl hydrazine and hydrogen iodide, respectively. The catalytic activity of coal chars treated by barium hydroxide was lower than the raw chars, while that of the chars treated by phenyl hydrazine or hydrogen iodide were higher. Hydroxy in the coal char was expended by Ba (OH)2. The initial methane conversion was achieved at about 90.5% for the Ba (OH)2 -treated char with equivalent-volume impregnation. The corresponding hydrogen yield was at about 65.2%. The carbonyl group of the coal char was reduced by phenyl hydrazine, with the methane conversion and hydrogen yield about 55.4% and 42.9%, respectively. The methane conversion and hydrogen yield decreased, while the ether bond turned into hydroxy. It was speculated that hydroxyl group in coal char restrain the methane cracking, while carbonyl group and ether bond accelerate it. The methane conversion and hydrogen yield on the different coal chars decreased with increasing reaction duration. The char became deactivated at 123min following its exposure to methane. The main reason was that the carbon from methane cracking was deposited on the char, which is supported by scanning electron microscopy analysis.
Abstract: The composition and reaction of mineral matters in rice straw and corn stalk were investigated in weak reducing atmosphere at temperature range of 550-1300℃. The FactSage was also used to simulate the evolution behaviors of mineral matters under high temperatures. The results show that the existing form of Na and K in biomass is relatively stable, including volatilized chlorides, silicates and sulphates with a lower melting point. The silicates made up of Si, Ca, Mg, Fe and Al have various forms, mainly including pyroxene, olivine and melilite. Pyroxene is transformed into olivine and melilite with the increasing of temperature. The interaction of the three kinds of materials could result in the generation of eutectics which could lead to the melting of mineral matters in biomass. The formation of cristobalite and mullite leads to a higher flow temperature of rice straw ash than corn stalk ash, the mullite ultimately is transformed into low melting point materials like clinoferrosilite, iron spinel and anorthite.
Abstract: The CuCe/AC catalysts were prepared by impregnation first with Ce and then with Cu, and effect of calcination temperature on catalytic performance of the CuCe/AC catalysts for gas-phase oxidative carbonylation of methanol to dimethyl carbonate was studied. The active component content and valence state of as-prepared catalysts were characterized by XRD, XPS and H2-TPR. The results show that Cu2+ is gradually reduced to Cu+ and Cu0 species. After calcinated at 450℃, some Cu2O phase still exists in the catalyst, which indicates that interaction between Cu and Ce has suppressed the reduction of Cu2O. As the calcination temperature of 300℃, the content of Cu+ achieves the highest, and the corresponding catalyst shows the best catalytic activity. The space-time yield of DMC, selectivity of DMC and conversion of methanol are 143.4mg/(g·h), 85.2% and 4.1%, respectively.
Abstract: Chemical-looping steam methane reforming (CL-SMR) is a novel method proposed on the base of chemical looping combustion (CLC) technology. In the CL-SMR scheme, methane is partially oxidized to syngas (H2/CO(molar ratio)=2.0) by the lattice oxygen in reformer reactor in the absence of gaseous oxidant, and then the reduced oxygen carrier is oxidized by steam to produce hydrogen in steam reactor. The use of perovskite type oxide LaFeO3 as an oxygen carrier in CL-SMR was studied. While the basicity of CaO/MgO modified oxygen carriers, LaFeO3-CaO and LaFeO3-MgO, were also synthesized aiming to increase specific surface area, thermostability, and resistance to coke formation. The synthesized oxides were characterized by X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), Brunauer-Emmett-Teller (BET) surface area and X-ray photoelectron spectroscopy (XPS). Three oxygen carriers exhibited high active and selective for syngas production from methane, and maintained perovskite type over cyclic redox operations. The LF-CaO sample is the best candidate for the CL-SMR of the three samples judging from the reactivity, selectivity, and resistance to carbon formation. It showed good regenerability during 5 redox reactions.
Abstract: Nickel immobilized on organically modified montmorillonite (Ni/OMt) was prepared by impregnation method and used as the catalyst for hydrogen production from ethanol steam-reforming; the Ni/OMt catalyst was characterized by XRD, FT-IR, H2-TPR, SEM, XPS and N2 adsorption-desorption. The results indicate that in comparison with the catalyst of nickel supported on unmodified montmorillonite (Ni/MMT), the Ni/OMt catalyst exhibits higher surface area and pore volume as well as higher nickel dispersion with smaller metallic particle size. For the ethanol steam-reforming over Ni/OMt, the conversion of ethanol keeps at 100%, with a selectivity of 70% to hydrogen during the 30h reaction test at 773K;however, over the unmodified Ni/MMT catalyst, severe carbon deposition is observed after reaction for only 10h, accompanying with catalyst deactivation and the formation of byproducts such as acetaldehyde and ethylene. The modification of MMT with cetyltrimethylammonium bromide (CTAB) can significantly improve the stability of the Ni/OMt catalyst in ethanol steam-reforming and reduce the carbon deposition rate by immobilizing highly dispersed nanoparticle Ni on the interlayers of OMt; the selectivity to ethylene and acetaldehyde is also greatly depressed.
Abstract: Hollow tungsten carbide and cobalt spheres (HTCCS) with cobalt concentration of 6% were prepared by spray conversion and reduction carbonization methods. The HTCCS with diameters of about 8-18μm were covered with 0.3-1.0μm microporous. The Pd/WC catalyst was prepared through the replacement reaction between Co nanoparticles on the surface of HTCCS and PdCl4. The electro-catalytic performances for formic acid electro-oxidation were investigated by cyclic voltammetry and chronoamperometry. It exhibited the low onset potential, excellent catalytic activity and stability compared with Pd/C due to the larger electrochemical surface area (ECSA) and the synergistic effect between Pd and WC.
Abstract: A series of LiMn2O4/TiO2 catalysts with spinel crystal structure were prepared by solid state reaction method, and the catalytic performance of oxidative coupling of methane on the different catalysts, such as TiO2, Li/TiO2, Mn/TiO2, LiMn2O4 as well as LiMn2O4/TiO2, was evaluated. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, CO2 temperature programmed desorption and H2 temperature programmed reduction. It is found that LiMn2O4 with spinel structure has high catalytic activity in oxidative coupling of methane reaction. 25.8% of CH4 conversion, 43.2% of C2 selectivity was obtained under the reaction conditions of 775℃, 0.1MPa, 7200mL·h-1·g-1, CH4:O2(volume ratio)=2.5. The introduction of TiO2 support can not only improve CH4 conversion and C2 selectivity, but also restrain the deep oxidation of methane to CO2. The LiMn2O4/TiO2 with 8% loading amount showed the best activity, on which 31.6% of CH4 conversion, 52.4% of C2 selectivity were obtained and CO2 selectivity was decreased to 26.3%. The effect of calcination temperature on the activity of LiMn2O4/TiO2 catalysts was investigated. 850℃ is the optimal calcination temperature.
Abstract: A serial of Au/HZSM-5 samples were prepared by vacuum deposition precipitation, cation exchange and vacuum sulfhydryl protection method. The effect of different preparation method, calcination temperature, calcination atmosphere and addition of potassium on the particle size and distribution of gold was invetigated. Based on the characterization of X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy and transmission electron microscope, it was found that the gold particle size of Au/HZSM-5 was changed greatly with different preparation methods. Gold particle size (about 2-5nm) of Au/HZSM-5 prepared by vacuum sulfhydryl protection was obviously smaller than that of the other preparation methods. Taken Au/HZSM-5 catalyst prepared by vacuum deposition precipitation as an example, low calcination temperature and inert atmosphere (nitrogen and argon) were favorable to the good dispersion of gold particles. The activities and carbonylation selectivities of syngas on Au/HZSM-5 catalysts were evaluated by a micro-fixed pulse reactor. 48% of syngas conversion and 52% of methyl acetate selectivity were obtained at reaction temperature of 350℃ over Au/HZSM-5 catalysts with 1.86% Au loading, calcined in air, while 59% and 70% were obtained over catalyst calcined in argon. By contrast, 67% of syngas conversion and 78% of methyl acetate selectivity were obtained over the catalyst calcined in nitrogen plasma.
Abstract: Composite CeO2-Al2O3 oxides with high surface area, large pore volume and large pore diameter were prepared by ultrasonic co-precipitation; with CeO2-Al2O3 as the support, Pt/CeO2-Al2O3 catalysts were obtained by impregnation method. The supporter and the as-prepared Pt/CeO2-Al2O3 catalysts were characterized by XRD, NH3-TPD, nitrogen sorption and SEM; their catalytic performance in the dehydrogenation of methylcyclohexane as a model compound was investigated in a micro tube-reactor and the influences of Ce/Al (mol ratio) and reaction temperature on the dehydrogenation activity were considered. The results indicate that the Pt/CeO2-Al2O3 catalyst with a Ce/Al (mol ratio) of 0.5 performs best at 450℃ in the dehydrogenation of methylcyclohexane, with a methylcyclohexane conversion of 88.53% and a selectivity of 94.63% to toluene.
Abstract: The catalysts of CuZnAl-1, CuZnAl-2 and CuZnAl-3 were prepared by the co-precipitation method using NaOH, Na2CO3 and Na2CO3/NaOH, respectively, as the precipitant. They were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, H2-temperature programmed reduction (H2-TPR), TGA, and NH3-temperature programmed desorption (NH3-TPD); the effect of precipitant on the performance of CuZnAl catalysts in the gas phase selective hydrogenation of furfural to furfuryl alcohol was then investigated in a fixed bed reactor. The results illustrate that all three catalysts exhibit high furfural conversion, whereas the CuZnAl-3 catalyst gives the highest selectivity to furfuryl alcohol. The precipitant has a great impact on the phase structure, surface area, acidity and redox property of the resultant CuZnAl catalysts. The CuZnAl-3 catalyst prepared with Na2CO3/NaOH precipitant exhibits proper specific surface area, CuO crystalline phase, weak acid sites and easily reducible CuO on the catalyst surface, which are conducive to produce furfuryl alcohol for the hydrogenation of furfural. Under the optimizing reaction condition, viz., atmospheric pressure, 180℃, hydrogen to furfural molar ratio of 5 and furfural volume space velocity of 0.3h-1, the conversion of furfural over the CuZnAl-3 catalyst reaches 99.4%, with a selectivity of 98.3% to furfuryl alcohol.
Abstract: The effects of alkali-treatment and alkali-acid-treatment of ZSM-5 on the catalytic properties and catalytic performance of benzene alkylation with methanol were studied. The results showed that alkali treatment of ZSM-5 can remove the extra-framework Si species to enhance the diffusivity. However, it can also neutralize the strong acid sites of ZSM-5 and weaken the activation of methanol, reducing the reactivity of benzene alkylation with methanol. The twice acid treatment of alkali-treated ZSM-5 improve the catalytic performance because it can not only remove the extra-framework Al species, but also restore a part of strong acid sites neutralized in the process of alkali-treatment. Further research on the effects of alkalinity showed that the extra-framework Al species and Si species can be removed and a moderate particle size can be obtained after treatment of ZSM-5 with a moderate concentration of alkali. Moreover, the carbon deposition rate has been slowed down due to a decrease of strong acid sites. Therefore, the conversion of benzene can be improved by more than 15%.
Abstract: The alkylation of isobutane with butene catalyzed by [Et3NH]Cl-AlCl3-CuCl ionic liquid was carried out in a continuous stirred autoclave reactor; deuterated isobutane was used as an isotope tracer to investigate the reaction mechanism of alkylation. The results indicate that the induction period of alkylation catalyzed by Cl-AlCl3-CuCl is less than 30min. Tri-methyl-pentanes are primarily produced from the self-alkylation of isobutane, the alkylation of isobutane with 2-butene and the cracking of C12+ intermediates, whereas the undesired di-methyl-hexane is mainly formed from the addition reaction between sec-C4+ and 2-butene.
Abstract: With the fixed loadings of molybdenum oxide of 13.50% and cobalt oxide of 2.11%, respectively, the Co-Mo/γ-Al2O3 catalysts were modified by adding different mass concentration of phosphoric acid via separate-step impregnation method. The effect of different phosphorus loadings of catalysts on the hydrodesulfurization performance was studied using middle temperature coal tar from Chifeng, Inner Mongolia. The structural properties of catalysts were characterized by the temperature programmed desorption of NH3 (NH3-TPD), XRD, XPS and other methods. The results show that a proper loading of phosphorus can weaken the interaction between the support and the active components, improve the dispersion of active compents on the surface of support, and promote the reduction and sulfuration of the active components and the distribution of acid, which can improve the hydrodesulfurization performance of the catalysts. The catalyst prepared with the phosphoric acid of 4% concentration exhibits the highest hydrodesulfurization activity with the sulfur removal of 96.98%. The effect of mass concentration of phosphoric acid on the hydrodesulfurization activety of the prepared catalysts is in the order of 4% >2% >6% >1% >0 >8%.
Abstract: WO3-TiO2/SBA-15 catalyst was prepared by inner-pore hydrolysis method; it was characterized by XRD, SEM, EDS, N2 sorption, FT-IR, TG-DTA and UV-vis and used in the photocatalytic oxidative desulfurization of diesel oil. The effects of WO3 and TiO2 loading and calcination temperature and time on the performance of the WO3-TiO2/SBA-15 catalyst in its photocatalytic oxidative desulfurization were investigated. The results indicated that the optimum loadings of WO3 and TiO2 were 1.6% and 15%, respectively, and corresponding calcination temperature and time were 500℃ and 3h, respectively. Over the WO3-TiO2/SBA-15 catalyst prepared under the optimum conditions, in which the hexagonal mesoporous structure was well retained, the desulfurization rate of model diesel oil reached 87.9%. Moreover, the WO3-TiO2/SBA-15 catalyst also exhibited excellent reusability after regeneration.
Abstract: The oxidation activity of elemental mercury (Hg0) by transition metal modified SCR catalysts was investigated by using the simulated SCR reactor. The physical and chemical properties of the catalysts were characterized by N2 adsorption-desorption and X-ray diffraction (XRD). The results show that the specific surface area and total pore volume of the catalysts are decreased after the modification by metal oxide. However, the pore structure and distribution after modification have little variation. The weak diffraction peaks of transition metal oxide can be seen from the XRD pattern. Both 8% Ce/SCR and 8% Cu/SCR catalysts show a relatively stable and high Hg0 oxidation efficiency, while the oxidation activity of the 8% Co/SCR catalyst is greatly influenced by temperature. The modified SCR catalysts have an excellent catalytic performance for the Hg0 oxidation under a lower concentration of NH3 and NO. And the Hg0 oxidation efficiency is promoted significantly in the presence of HCl. On the contrary, there is little improvement in the Hg0 oxidation by HCl at the condition of higher concentration of NH3 and NO.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
