Abstract: In this study chemical-looping combustion of methane with compound CaSO4 oxygen carrier prepared by impregnation method was investigated in a fixed bed reactor. The effects of reaction temperature, CH4 percent, particle size and sample mass on reduction were discussed and an appropriate condition was determined by contrastive experiments. The results show that Ni-Fe mixed additive greatly improves the reactivity of CaSO4, and the suitable reaction temperature is around 925℃. Carbon deposition is inhibited and higher gas conversion is obtained by lower CH4 percent and more sample mass. However, the sample particle size has a little effect on the reduction. The long-time reduction-oxidation test demonstrates that compound CaSO4 oxygen carrier has a higher conversion. X-ray diffraction analysis reveals that CaSO4 could be fully reduced into CaS which is also almost oxidized into CaSO4.
Abstract: Due to the high absolute humidity of real flue gas, activated carbon, a hydrophobic adsorbent, was used to selectively adsorb CO2 by vacuum swing adsorption in this study. The objective of this work is to study the feasibility and advantage of CO2 capture along with simultaneous moisture removal by activated carbon and the effect of H2O on CO2 capture from wet flue gas streams. Through experiment and analysis, the “S” shape isotherms of water indicated water was easier to be desorbed from activated carbon. Then a cone shape model was proposed to depict water distribution inside the adsorption bed. As a consequence, water vapor hardly influenced the CO2 capture performance. Moreover, the process can be operated under a relatively high vacuum pressure and short evacuation time. The preliminary results showed that our one-bed VSA process could yield a good CO2 recovery of over 80% and a reasonable purity of 43%.
Abstract: The release of NO from coal char combustion under the atmosphere of different CO2 concentrations was investigated in a high temperature gas-solid reactor with suspension and spray. The effects of temperature and cement raw meal on the release of NO under different CO2 concentrations were discussed. The results indicate that with the increase of CO2 concentration, the rate of NO release, the peak value of NO concentration and the percent conversion of char-N to NO decrease. The percent conversion of char-N to NO greatly rises due to the catalysis of cement raw meal, while the catalysis of the cement raw meal becomes weakening with the increase of CO2 concentration. It is also found that the conversion of char-N to NO increases with the rise of temperature. However, the effect of temperature on the NO release reduces with the increase of CO2 concentration.
Abstract: Direct deoxygenation effect of CaO on bio-oil from biomass pyrolysis was studied in a fluidized bed experimental apparatus. Bio-oil was produced at reaction temperature of 520℃ and carrier-gas flow-rate of 8000L/h using white pine alone and white pine accompanied with CaO, respectively. The result shows that the oxygen contents of the organic components in the bio-oils are 39.38%, 39.15%, 39.04% and 32.29% for white pine alone and white pines with 1, 2, 4 times of CaO added, respectively. With 4 times CaO added, the oxygen content of the organic components decreases by 18.0% (relative variation). Detailed GC-MS analysis indicates that the relative contents of high-oxygen containing levoglucosan, formic acid, acetic acid, etc. are greatly reduced with CaO-adding, implying the existence of the oxygen-capture path of “high-oxygen containing intermediates” in biomass pyrolysis process. Furthermore, the species of furfural is derived from dehydration reactions, and the increase in the relative content demonstrates that CaO-adding can also catalyze the dehydration reactions.
Abstract: In order to know the influence of the composition of fatty acid methyl ester (FAME) on the low-temperature fluidity of biodiesel, and to find the way to improve it, the soybean oil methyl ester, peanut oil methyl ester and tallow oil methyl ester were synthesized from soybean oil, peanut oil and tallow oil. Their FAME composition and low-temperature fluidity have been determined. The results show that saturated long chain FAMEs are the main reason to influence the fluidity of biodiesel. The fluidity of biodiesel blends suggests that mixing FAMEs from different sources would decrease its pour point（PP） and cold filter plugging point （CFPP）. The improvement of fluidity by blending is greater than that of adding fluidity improver into high-PP biodiesels. Furthermore, the mechanism of crystallization of FAME was analyzed by observation from polarized light microscope.
Abstract: Pyrolysis is one of the promising disposal outlets of sewage sludge, which can not only solve the environmental problem but also obtain gas and liquid fuels. In this study, the pyrolysis oil of sewage sludge was obtained in a fixed bed. Distillation, widely used in chemical industry, was employed for pyrolysis oil process to get the light fraction termed as gasoline-like fraction. It is found that the hydrocarbon chain length of the gasoline-like fraction distributes across the C6~13 which is close to that of gasoline. It is a complex mixture of many organics including 24.32% alkanes, 36.33% alkenes, 22.96% aromatics and 16.39% N- and O- containing compounds. Except for serious smell and high sulfur content, the gasoline-like fraction is close to the real gasoline for motor vehicle for the characters of distillation, Cu strip corrosion, mechanical admixture and the content of unsaturated hydrocarbon. The comparison of the gasoline-like fraction with gasoline for motor vehicle indicates that the former has the potential to substitute for fossil gasoline.
Abstract: Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃~550℃ in order to obtain suitable liquid fuels. The dependencies between process temperatures, types of catalyst, feed compositions and product yields of the obtained fuel fractions were found. It was observed that up to 450℃ thermal cracking temperature, the major product of pyrolysis was liquid oil and the major product at other higher temperatures (475℃~550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃. Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid fraction. Again the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid oil. Silica alumina was found better as compared to kaoline in liquid yield and in reducing the reaction temperature. The maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% respectively. On the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.
Abstract: Various surfactants were added during the synthesis of pillared clays Ti-PILCs to modify their structure and properties. Zn supported on the surfactant-modified Ti-PILCs (Zn/Ti-PILCs) was used as a desulfurization adsorbent and its performance in desulfurization of a model diesel oil containing dibenzothiophene (DBT) was investigated. The results showed that the capability of Zn/Ti-PILCs for DBT selective adsorption is enhanced by the surfactant modification. Especially, Zn/Ti-PILCs-CTAB obtained through modification with hexadecyl-trimethyl-ammonium bromide (CTAB) (CTAB/Ti molar ratio being 0.5) exhibits high desulfurization performance with a DBT removal rate of 96.3%. The characterization results of nitrogen sorption indicated that the surfactants added during the pillaring process can increase the surface area of the resultant Ti-PILCs and improve their pore distribution by enhancing the amounts of mesopores (1nm~4nm).
Abstract: The effect of high temperature carburization on the catalytic performances over an ultrafine Fe-Mn catalyst was investigated. The surface area of the catalyst distinctly decreased after carburization. The carburization process favored the formation of FeO-MnO spinel phase and α-Fe, and small iron carbide crystallite was also formed. The catalyst after carburization exhibited high light olefin selectivity and low methane selectivity during CO hydrogenation, also, the chain propagation ability was promoted. The characterization of the catalyst indicated that the surface properties of the catalyst after carburization were improved. The carburization process enhanced the basicity of the catalyst and suppressed the secondary reactions of hydrogenation, and resulted in high selectivity to light olefins.
Abstract: A series of spherical FeCuK/SiO2 catalysts for slurry Fischer-Tropsch synthesis (FTS) were prepared by the spray drying method. The effects of incorporation manner of Cu on the crystallite structure, the reduction and carburization behaviors were studied by H2 temperature-programmed reduction (H2-TPR) and Mssbauer spectroscopy. The catalytic performances were evaluated in a slurry reactor under the industrial relevant reaction conditions of 250℃, 1.5MPa, H2/CO=0.67 and a space velocity of 2.0L/gcat-h. The result indicated that the coprecipitated Cu was well dispersed in iron phase, which promoted the reduction, carburization of the catalyst and the catalytic activity. The addition of respective precipitated Cu suppressed the reduction and carburization of the catalyst. All catalysts were stable during 500h on stream. For the hydrocarbon selectivity, the addition of the coprecipitated Cu increased the selectivities of heavy hydrocarbons and olefins, and restrained the formation of oxygenates, compared with others.
Abstract: Bimetallic Ni-Fe/γ-Al2O3 catalyst and monometallic Ni/γ-Al2O3, Fe/γ-Al2O3 catalysts were prepared by wet impregnation method; they were characterized by XRD, N2 physisorption, H2-TPR, H2-TPD and TPSR. The activity of these catalysts in CO methanation was investigated in a fixed-bed continuous flow reactor. A significant Ni-Fe interaction is observed in the bimetallic Ni-Fe/γ-Al2O3 catalyst; Ni-Fe alloy is formed during reduction, which can promote the adsorption of hydrogen. Under the reaction conditions of 0.5% CO, GHSV of 5000h-1 and atmosphere pressure, the bimetallic Ni-Fe/γ-Al2O3 catalyst exhibits high catalytic activity; CO can be completely converted into methane at 220℃.
Abstract: NiO with different morphologies were prepared by precipitation method and then the NiO/γ-Al2O3 catalysts were prepared from NiO and γ-Al2O3 by grind-mixing method. These catalysts were characterized by means of TEM, XRD and H2-TPR techniques. TEM images show that the morphologies of three NiO phases (a-NiO, b-NiO and c-NiO) obtained are in the shape of rod, granule and sheet, respectively. H2-TPR profiles show that the oxidabilities of these catalysts are in the order of b-NiO/γ-Al2O3 < a-NiO/γ-Al2O3 < c-NiO/γ-Al2O3. XRD patterns show that the crystalline sizes of Ni in these catalysts after reduction are in the order of b-Ni > a-Ni > c-Ni. CO methanation was carried out over the Ni/γ-Al2O3 catalysts in a continuous flow fixed-bed reactor and the effects of mixing method and morphology of active species on the catalysts performance were investigated. It is found that the catalyst prepared from grind-mixing exhibits higher activity and stability than that obtained from simple-mixing. The catalytic activities of these catalysts with different morphologies for CO methanation follow the order of c-Ni/γ-Al2O3 > a-Ni/γ-Al2O3 > b-Ni/γ-Al2O3. Over the c-Ni/γ-Al2O3 catalyst (wNi = 15%) under the conditions of atmospheric pressure, 593K and a space velocity of 2500h-1, the conversion of CO and the selectivity to CH4 reach 99.63% and 90.80%, respectively.
Abstract: Pure CeO2, Fe2O3 and a series of Ce0.5Fe0.5-xZrxO2 mixed oxide catalysts for soot catalytic combustion were prepared via hydrothermal method and characterized by XRD, Raman spectroscopy, H2-TPR and BET measurements. The catalytic activities in the diesel soot oxidation were tested by using temperature-programmed oxidation (TPO) reaction apparatus. The results show that all of the Zr4+ incorporated into the CeO2 lattice to form a solid solution. On the other hand, Fe3+ is extremely difficult to dissolve into the CeO2 lattice, and some Fe2O3 disperses on the surface of solid solution. The partial substitution of Ce4+ with Zr4+ and/or Fe3+ strongly improves the aging resistance of the catalysts. The strong synergetic effect between free Fe2O3 and surface oxygen vacancies wearies believed to have a pronounced positive effect on catalyst activity towards soot oxidation. Holding both the largest dopant content and well dispersed surfaceFe2O3, the Ce0.5Fe0.30Zr0.20O2 catalyst presents the lowest ti (251℃, ignition temperature of soot oxidation) and tp (310℃, temperature of maximum evolution of CO2). Even after aging for a long period at high temperature, the ti and tp values for Ce0.5Fe0.30Zr0.20O2 catalyst are still relatively low, at 273℃ and 361℃, respectively.
Abstract: The selective hydrogen combustion (SHC) in the presence of n-hexane was studied over Pt-Sn/Al2O3 catalyst to investigate the feasibility of directly heat supply for pyrolysis process. With air as the oxygen source and n-hexane as the representative of cracking hydrocarbons feedstock, the selective hydrogen catalytic combustion was compared with hydrogen non-catalytic combustion under various temperatures. The results indict that Pt-Sn/Al2O3 is a good catalyst for SHC; the selectivity of Pt-Sn/Al2O3 catalyzed hydrogen combustion is remarkably higher than that of non-catalytic hydrogen combustion. There exists a critical temperature for Pt-Sn/Al2O3 catalyzed SHC reactions. The selectivity of catalytic SHC keeps at 90% when the feedstock inlet temperature is below 650℃; however, it decreases at elevated inlet temperature. Moreover, the ratio of hydrogen to hydrocarbon and the ratio of hydrogen to oxygen may also significantly influence the selectivity of SHC under certain temperature.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
