Abstract: In order to make use of coal direct liquefaction residue efficiently, co-pyrolysis of Hulunbuir lignite and direct liquefaction residue (DLR) of Shendong coal were conducted in a fixed bed reactor under atmospheric pressure. The physicochemical properties of co-pyrolysis semi-coke were analyzed by scanning electron microscope, nitrogen adsorption-desorption, X-ray diffraction, Raman spectroscopy and thermogravimetric analyzer. The results show that DLR semi-coke and lignite semi-coke are cohered each other, because the DLR is softened and melted during co-pyrolysis. The specific surface area and pore volume of co-pyrolysis semi-coke decrease. Characterization of both XRD and Raman spectroscopy indicate that the order degree of co-pyrolysis semi-coke increases with the addition of DLR. Compared with the lignite semi-coke, the CO2 gasification reactivity of co-pyrolysis semi-coke decreases.
Abstract: A high-frequency furnace was utilized to carry out rapid pyrolysis of Shenfu coal. The effect of temperature and residence time on the properties of solid and gas products was studied. The results show that the mass loss and true density of the char increase with increasing of both temperature and time. The analysis of their infrared spectra indicates that the hydrogen/oxygen functional groups decompose to form H2, CO, CO2, CH4 and other gases during pyrolysis, and the decomposition increase with increasing temperature and time. The emission of H2 and CO monotonically increases, however there are emission peaks for CO2 and CH4. The total gas products increase with temperature and time, leading to the pores and cracks on the char after high temperature pyrolysis.
Abstract: Two different systems for vitrinite and inertinite from Wucaiwan coal were established:no interaction (A) and interaction system (B). Thermogravimetric (TG) and fouriertransform infrared (FT-IR) were used to analyze the pyrolysis products in the two systems. The results show that at 300~450℃ the hydrogen content of B is higher than that of system A, indicating that the reaction of alkyl radical transfer between the vitrinite and inertinite. Meanwhile, the aromatic hydrogen of system B is more than that of system A, which shows that aromatization between vitrinite and inertinite occurs, and a few hydrogen free radicals produced from vitrinite occur macromolecular aromatic structure side chain substitution reaction with inertinite. From 500 to 700℃, the aliphatic and aromatic hydrogen content of system B is lower than that of system A, showing that polycondensation reaction and condensation reaction exist between the vitrinite and inertinite. From 750 to 800℃, aromatic aliphatic hydrogen content of system B is greater than that of system A, which means that vitrinite generates more hydrogen free radicals and occur hydrogenation reaction with inertinite macromolecular aromatic structure as well as side chain substitution reaction with inertinite in system B; From 850 to 900℃, polycyclic aromatic condensation reaction proceeds further between vitrinite and inertinite.
Abstract: In order to understand the slagging properties of blended coal, different coal blending and flux agent were added to Jincheng anthracites. The X-ray diffraction (XRD), thermodynamic software FactSage and ash fusion temperature (AFT) test were employed to analyze the ash fusion characteristics of blended coals and the mineralogical properties of the blended coal ashes. The results show that the content of ash in coal has an important role in the AFT change of blended coals. The lower the ash contained in raw coal is, the easier the AFT of blended coal lowers. The addition ratio of coal blending is 20% and 30% when the AFT decreases significantly for coal C with low ash content and G with high ash content, respectively. There is more significant fluxing effect of K on C than that on G. It is found that the feldspar mineral is formed at the deformation temperature. The decreasing in contents of mullite as well as the appreciably increasing for feldspar is the main reason for the decreasing of AFT. The thermodynamic analyses indicate that the producing of liquid matter is related to the rapidly decreasing in the contents of anorthite and quartz, as well as slowly decreasing for mullite at high temperature. The anorthite takes part in the formation of liquid matter. The fluxing effect of anorthite depends on the contents of matter which can react with anorthite to produce a melt with lower fusion point.
Abstract: Interactions of catalyst (K2CO3) with Shenfu (SF)/Zunyi (ZY) char during gasification were observed by in-situ heating stage microscope. The effects of gasification temperature (750~950℃) and catalyst loading amount (2.2%, 4.4%, 6.6%) were investigated in a thermogravimetric analyzer. The results show that loading K2CO3 on SF/ZY stimulates development of pore structure in pyrolysis process. The in-situ heating stage experiments indicates that most of the char particles react with CO2 in shrinking core mode below the melting point of K2CO3. Above this temperature, for SF char, obvious molten potassium catalyst diffusion can be observed in the later reaction stage with rapid consumption of carbon skeleton; but for ZY char, most of the molten potassium exists on the surface of coal char with slower consumption of stable carbon skeleton. Gasification reactivity of SF/ZY char increases with increasing loading amount of K2CO3. Catalytic efficiency of potassium catalyst on SF char initially increases and then decreases with gasification temperature, the turning point of gasification temperature is close to the melting point of K2CO3. This may be due to blocking of a fraction of pore structure resulted from the good fluidity of molten potassium catalyst.
Abstract: The influence of o-cresol on HDN of quinoline, HDS of DBT and HDA of 1-methylnaphthalene were investigated over a commercial catalyst in a fixed bed micro-reactor. The results suggest that o-cresol could strongly inhibit the HDN reaction of quinoline, HDS of DBT and HDA of 1-methylnaphthalene. The inhibition effect increases with the increasing content of o-cresol, which is resulted from the competitive adsorption between o-cresol and quinoline, DBT, and 1-methylnaphthalene. The presence of o-cresol has little effect on product selectivity. The hydrogenation is favored for aromatic ring without side chain, which is accounted for the steric effect.
Abstract: β-O-4 is the primary type of linkages among the main lignin structure units. The pyrolysis of lignin dimer model compound of β-O-4 linkage was investigated by using density functional theory B3LYP methods at 6-31G(d,p) level. Three possible pyrolysis pathways were proposed:the subsequent reactions after the homolytic cleavage of Cβ-O bond, the subsequent reactions after the homolytic cleavage of Cα-Cβ bond and the concerted reactions. The equilibrium geometries of the reactants, transition states, intermediates and products were optimized and the standard kinetic parameters for each reaction pathway were calculated. The formation mechanism of the main pyrolysis products and the effect of temperature on the pyrolysis mechanism of lignin dimer were analyzed. The calculation results show that the subsequent reaction pathways after the homolytic cleavage of Cβ-O bond and the concerted reaction pathways (1) and (3) are the major reaction channels, whereas the subsequent reaction pathways after the homolytic cleavage of Cα-Cβ and the concerted reaction pathways (2) and (5) are the competitive reaction channels in the pyrolysis process. The main pyrolysis products are phenolic compounds such as guaiacol, 1-guaiacyl-3-hydroxy-acetone, 1-guaiacyl-3-hydroxy-propaldehyde and guaiacyl-formaldehyde. In the pyrolysis process of the lignin dimer, the concerted reactions dominate over the free-radical homolytic reactions at low temperature, whereas but the free-radical reactions prevail over the concerted reactions at high temperatures.
Abstract: The effects of different model nitrogen containing compounds on the catalytic cracking of o-xylene were investigated in a fixed bed. The adding amount of N element was 4000μg/g and the active component of the catalyst was USY zeolite. The results indicated that the conversion of o-xylene is reduced by adding pyridine or quinoline. On one hand, the increase in coke yield after adding acridine is related with its adsorption on catalysts. On the other hand, acridine induces o-xylene to produce more coke and hydrogen, promoting the hydrogenation and opening reactions of aromatic rings. Compared with the blank test, the conversion of o-xylene is improved slightly by adding acridine, and both the yield of dry gas and the yield of LPG increase greatly.
Abstract: A series of alumina with similar textural properties but different acidities were prepared and used as the matrix components of the FCC catalysts. The effect of acid type of matrices and contacting order of acid sites of different types on the yield of LPG olefins in catalytic cracking of heavy vacuum gas oil (HVGO) was investigated. The results showed that the matrix is more conductive to the formation of LPG olefins from the aspect of reaction route, in comparison with the REUSY molecular sieves. When there are Brönsted acidity on the matrix surface and/or HVGO molecules first contact with Lewis acid sites and then react with Brönsted acid sites during the matrix-precracking process, cracking reactions are enhanced while hydrogen transfer reactions are restricted, which facilitate to increase the yield of LPG olefins.
Abstract: Ni-based catalysts with different supports were prepared for methane dry reforming. The obtained catalysts were characterized by N2 physisorption, XRD, H2-TPR, H2-chemisorption, and so on. It was revealed that the support had significant influence on the state of NiO species. SiO2, TiO2 and ZrO2 had weak interaction with NiO, facilitating the reduction of the corresponding catalysts. Al2O3 and MgO have strong interaction with NiO, making them very difficult to be reduced. Al2O3 modified by MgO has both proper texture properties and interaction strength between metal and support, which were in favor of the dispersion and stabilization of NiO species. Superior catalytic performance was observed over this catalyst under very high gas hourly space velocity. Stable catalytic performance was achieved during a long term run of more than 100h.
Abstract: A series of CuO/ZnO/CeO2-ZrO2 catalysts for methanol steam reforming were prepared by a co-precipitation procedure, and the effect of precursor and precipitant concentration on the catalytic perforemance was investigated. All the catalysts were characterized by N2 adsorption, XRD, H2-TPR, and XPS. It is shown that the precursor and precipitant concentration remarkably influenced the catalyst structure and property. When the precursor concentration was 0.1mol/L and the precipitant concentration was 0.5mol/L, the catalyst exhibited the best activity with suppressed CO formation. During 360h run time, the highest methanol conversion reached 100%, the H2 concentration was above 74.5%, and the CO concentration was below 0.8% in the reforming gas. The catalyst had excellent reforming performance without deactivation during 360h run time.
Abstract: Various metal oxides and metallic salts were used as a catalyst in the synthesis of dimethyl carbonate (DMC) from urea and methanol in an autoclave. The results indicated that the hydrated metallic salt is most catalytically active in DMC synthesis among various metal oxides and salts considered in this work. Furthermore, a binary catalyst, viz, Zn(NO3)2 combined with hydroxyl containing compounds, can noticeably enhance the yield of DMC, in comparison with the single catalyst of both Zn(NO3)2 and the hydroxyl containing compound, which may be ascribed to a synergistic effect between Zn(NO3)2 and the hydroxyl group. Among various binary catalysts, Zn(NO3)2-SiO2 exhibits the best catalytic performance; the yield of DMC reaches 4.5% over Zn(NO3)2-SiO2 with a Zn(NO3)2 to SiO2 weight ratio of 2.
Abstract: Silica was treated with trimethylchlorosilane before using as the supports for Rh-Mn-Li catalysts in CO hydrogenation to C2 oxygenates. The catalysts were characterized by infrared spectroscopy, N2 adsorption-desorption, C content measurements, transmission electron microscopy, H2 temperature programmed reduction, and temperature programmed surface reaction. The results showed that the silanization degree has little effect on the textural properties of silica. The mean Rh particle size (about 3nm), CO adsorption state on Rh and reducibility of Rh supported on silica remain unchanged by the silanization of silica support. However, with an increase of the silanization degree of silica, the ability of Rh to dissociate CO is improved, which can enhance the catalytic activity of Rh-Mn-Li/SiO2 in CO hydrogenation but has little influence on the selectivity towards C2 oxygenates.
Abstract: FeAl precursors (remarked as P) were prepared by co-precipitation method. Then they were impregnated with promoter Zn, K and Cu into ZnKCu/FeAl catalysts (remarked as C). The precursors and catalysts were characterized by low temperature N2 adsorption, XRD and H2-TPR. CO2 hydrogenation over these catalysts was investigated in a fixed-bed reactor. With the addition of Al, the specific surface area of FeAl precursors and ZnKCu/FeAl catalysts was increased relative to that of Al-free samples. On the contrary, the crystallite size of a-Fe2O3 was decreased by the added Al. The dispersed degree of Cu was raised in the catalysts containing Al. It is benefit for the reduction of ZnKCu/FeAl catalysts. However, the specific surface area and a -Fe2O3 crystallite size of P-10 and C-10, in which the Al2O3/Fe2O3 mass ratio is 10%, were similar to those of P-5 and C-5 with 5% Al 2O3/Fe2O3 mass ratio, respectively. The phenomena were resulted from the strong g-Fe2O3 phase in P-10 and C-10. It was evidenced that g-Fe2O3 was formed only in the case of Fe and Al were co-precipitated, and the precipitate was washed by anhydrous ethanol in this study. The catalyst with strong g-Fe2O3 phase was more active in CO2 hydrogenation than the catalysts with none or weak g-Fe2O3 phase. This correlation was supported by the comparison between two catalysts with the same Al content, but different Fe2O3 phases in them.
Abstract: TiO2-SnO2 mixed oxide was prepared by a co-precipitation method and xCeO2/TiO2-SnO2 catalysts were prepared using the impregnation method. The physicochemical properties were investigated by X-ray diffraction (XRD), BET specific surface area measurement, H2 temperature-programmed reduction (H2-TPR), NH3 temperature-programmed desorption (NH3-TPD), high-resolution transmission electron microscopy (HRTEM), and in situ diffuse reflectance infrared spectroscopy (DRIFTS). Meanwhile, their catalytic performance for the selective catalytic reduction of NOx with NH3(NH3-SCR)was tested. It was found that 0.1Ce/TiO2-SnO2 had higher NOx conversion and wider temperature range of 250~350℃. Excess loading of CeO2 could lead to the decrease of specific surface area, redox ability and adsorption capacity of ammonia as well as the shrink of effective catalytic temperature range. NH3-TPD result showed that the adsorption of NH3 in weak acid and medium acid sites were significantly enhanced by CeO2, which was related to the decrease of NH3-SCR reaction temperature. In situ DRIFTS indicated that the strength of Lewis acid sites and Brønsted acid Sites were markedly enhanced for xCeO2/TiO2-SnO2 catalyst. Besides, new Brønsted acid Sites appeared at 1657~1666cm-1 and NH4+ played the dominant role in the SCR reaction.
Abstract: Chemical looping combustion (CLC) for sewage sludge has a relatively low efficiency using hematite as oxygen carrier. The experiments on improving the reactivity of hematite with cement modified for CLC of sewage sludge in a 1kWth continuous CLC unit were carried out. Compared to hematite oxygen carrier, the concentrations of unconverted combustible gas rapidly decrease when the cement-hematite is used. Moreover, both carbon conversion and combustion efficiency increase when the cement is added. Although some ash particles deposit on the surface of oxygen carrier and a part of Fe2O3 is reduced to FeO, there are no defluidization and sintering problems.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
