Abstract: In order to comprehensively understand the catalytic gasification process, the influence of AAEMs during coal thermal chemical conversion was compared and explained. The main issues related to the catalytic gasification, such as the transformation of carbon structure, the conversion of alkali metals, and the deactivation of catalysts were discussed. AAEMs can be used as the catalysts for catalytic gasification, the pore making additives for activated carbon preparation, the activating agents in the process of aluminum extraction from coal ash by roasting, but also be regarded as hazard elements for high AAEMs coal utilization. The interaction between AAEMs and carbon can affect the surface structure of carbon to favor the adsorption and reaction of gasification agent on the carbon surface. As the same time, the volatilization and release of AAEMs can not be escaped, but the catalyst recovery can be effectively promoted by coupling the catalytic gasification and the coal ash resource utilization. By understanding the effect of AAEMs on coal thermal chemical conversion, we can propose novel ideas and innovation techniques for coal thermal chemical conversion with AAEMs addition.
Abstract: A superhigh-organic-sulfur (SHOS) coals were chosen to study the environmental causes of Heshan coal origin. Based on routine analysis such as scanning electron microscope (SEM-EDX) observation, gas chromatograph (GC) and gas chromatograph-mass spectrometry (GC-MS), the composition and molecular geochemical features of organic matter were analyzed to deeply reveal the organic matter sources, sedimentary environments and provenance inputs. The results indicate that the average vitrinite reflectance of the samples is 1.76%, and the average total sulfur is 6.01%, among which the organic sulfur content accounts for 94.3%, belonging to a high-maturation super high organic sulfur coal. Unresolved Complex Mixtures(UCM) bulge is obvious in the saturated hydrocarbon chromatogram, both front and bimodal peaks are found. The main carbon peaks of the front peak type are C16, C18, C21 and the bimodal is C18 and C27. Meanwhile, these compounds norpristane, dehydroabietane, cadalene have been found in samples, and regular sterane C27, C28, C29 show a "V" type distribution, which indicates that sedimentary parent material is affected by the double input of lower aquatic organisms and high plants. The distribution of hopane in C31-35 decreases stepwise, and the ratio of pristane to phytane shows that there are certain oxidation conditions in the coal-forming zone of marine carbonate platform. Fe (Si, Al)-oxysulfate and cell-filled pyrite observed by SEM indicate that the sedimentary diagenesis is affected by hydrothermal process to some extent in the diagenetic stage of late sedimentary facies.
Abstract: Hβ zeolite was modified with different contents of F to prepare the Mo-Ni/F-Hβ catalysts. The Mo-Ni/F-Hβ catalysts were characterized by nitrogen physisorption, NH3-TPD, XRD, Py-FTIR and SEM; the effect of modification to Hβ with F on the catalytic performance of Mo-Ni/F-Hβ in the sulfur transfer reactions such as etherification of mercaptan and alkylation of thiophene in FCC gasoline was then investigated. The results indicate that the Mo-Ni/F-Hβ catalyst prepared with 0.5% F-modified Hβ zeolite can promote the thioetherification and thiophene alkylation reactions and improve the selectivity of dienes hydrogenation. The introduction of F can enhance the medium strong acid content of Hβ zeolite, reduce the strong acid content, and increase the ratio of L/B acid sites, all these may contribute to improving the catalytic performance of Mo-Ni/F-Hβ in the sulfur transfer reactions of FCC gasoline.
Abstract: The catalytic hydropyrolysis of pine wood was conducted in a fixed bed reactor under a H2 pressure of 5 MPa at different temperatures (600-700 ℃) to investigate the effects of two iron salts, Fe(NO3)3 and FeSO4, on the upgrading of bio-oil and gaseous products. Fe(NO3)3 is found to promote the conversion of biomass to bio-oil and gaseous products, with a carbon conversion rate as high as 97.4%, a CH4 yield of 21.2%, and a bio-oil yield of 32.8% (daf. biomass basis). Moreover, the oxygen content in the bio-oil decreases, the yield of light aromatic hydrocarbon increases and the yield of BTX (benzene, toluene and xylene) reaches 2.6%. In contrast, FeSO4 has an inhibitory effect on the production of gaseous hydrocarbons and bio-oil. The XRD analysis shows that Fe(NO3)3 is transformed to α-Fe during hydropyrolysis, with the amorphous and porous structures of bio-char being formed. This is highly conducive to the catalytic hydrogenation and methanation of bio-char. But FeSO4 is converted to Fe2S3 during the hydropyrolysis, which might poison the catalytic activity.
Abstract: A catalyst support of mesoporous MgO was prepared using hydrothermal method, with which a mesoporous Ni/MgO catalyst was prepared by impregnation method. The hydrogen production experiment by steam reforming of biomass oil models and two kinds of commercial biomass oils over the mesoporous Ni/MgO catalyst was conducted. The results show that the furfural conversion, hydrogen yield and hydrogen selectivity increase with increasing the reaction temperature. When the reaction temperature is increased to 600 ℃, the furfural conversion and the hydrogen yield reach 94.9% and 83.2%, respectively. In addition, the hydrogen yields for steam reforming of furfural/acetic acid and furfural/hydroxyacetone reach 87.3% and 86.8%, respectively, which are higher than the corresponding hydrogen yields in steam reforming furfural. The result indicates that the acetic acid or hydroxyacetone can promote the conversion of furfural which is the main organic component in the simulated biomass oil. When the commercial biomass oils is used, the conversion of main organics, hydrogen yield and hydrogen selectivity exhibit an increasing trend with the increase of the ratio of water to the carbon of reactant (S/C = 5, 10, 15, 20, 25). Under the S/C(molar ratio)=20, the conversion of main organic components (furfural, acetic acid, and hydroxyacetone) in two kinds of biomass oils can reach more than 90% and the yield of hydrogen can also be more than 81.0%, showing that the mesoporous Ni/MgO catalyst also has higher catalytic activity for the steam reforming of commercial biomass oils.
Abstract: The catalytic oxidation of CO was comparatively investigated on the Pd slab and Pd38 cluster models by density functional theory (DFT) calculation, in order to reveal the mechanism of CO oxidation over Pd catalysts. The results show that the rate-determining step of CO oxidation on the Pd38 cluster is the dissociation of O2, with the energy barrier of 0.65 eV, whereas the oxidation of CO turns to be the rate-determining step on Pd slab, with the energy barrier of 0.87 eV. Obviously, the oxidation of CO on the Pd38 cluster is much easier than that on the Pd slab, suggesting that the activity of Pd catalysts is related to the dispersion of active Pd species; the Pd catalyst with higher Pd dispersion also exhibits higher activity in CO oxidation.
Abstract: In this paper, the effect of Cu single atom modification on the adsorption of CO and electronic properties of Fe (111) surface has been studied by density functional theory (DFT). Two ways of adsorption and substitution have been studied for Cu mono-atom modification. The results show that the adsorption capacity of CO on the Cu modified Fe (111) becomes weak. One reason is that the sites provided by the Cu atom itself are weak for CO, and the other is that Cu weakens the adsorption of CO on the Fe nearby Cu. The analysis of electronic properties indicates that when Cu acts on the Fe (111), the part electrons of Fe can be transferred to the Cu, which weakens the electronic interaction between Fe and adsorbed molecules, and adjusts its adsorption capacity. Therefore, the Fe surface modified by Cu atom can well adjust the adsorption, dissociation and subsequent reaction catalytic activity of CO, which provides basic information to further explore the syngas catalytic reaction mechanism of Cu modified Fe surface.
Abstract: A series of transition metals (Fe, Cu, Zr) modified Mg-Al solid bases were synthesized by co-precipitation method and characterized by XRD, N2 adsorption-desorption, FT-IR, XPS, CO2-TPD. The catalytic performances were investigated for the synthesis of dimethyl carbonate via transesterification of propylene carbonate (PC) and methanol. The results reveal that the surface basicity of the samples varies with the addition of different metals. The surface basic strength and density of the catalysts are the main factors affecting the catalytic activity. Among the catalysts studied, FeMgAl exhibits the highest surface basic density and thus shows the best catalytic performance. The conversion of PC can reach 66.2% under the temperature of 65 ℃, reaction time of 4 h, methanol/ester molar ratio of 10:1 and catalyst amount of 4% of the reactant.
Abstract: A series of xMg@MCM-41(x=0, 0.05, 0.1) functional mesoporous materials were synthesized by a novel in-situ one pot method and then were used as support for Ni based catalysts. The results of XRD and TEM show that when the amount of Mg/Si (molar ratio) is 0.05, Mg@MCM-4 with a regular and ordered mesoporous structure is synthesized where Mg is introduced into the framework of MCM-41. Introducing Mg into the framework of the support can significantly enhance the basic properties of the catalyst, thus promoting the adsorption and activation of CO2. The catalysts prepared in the experiments all have good thermal stability and catalytic activity. Among them, Ni/0.05Mg@MCM-41 shows the best low temperature reaction activity in the CO2 methanation reaction.
Abstract: CeO2 supports with different morphologies (including spherical CeO2-S, bud-shaped CeO2-F, and polyhedral CeO2-P) were synthesized and the supported Ni/CeO2 catalysts were prepared by ammonia-water coordination impregnation method; the effect of CeO2 morphology on the catalytic performance of Ni/CeO2 in CO methanation was then investigated. The results indicate that CeO2-S, CeO2-F, and CeO2-P supports are rather different in the exposed crystal planes and oxygen vacancies, which have a significant effect on the catalytic performance of Ni/CeO2 in CO methanation. In particular, CeO2-S has the most oxygen vacancies; for CO methanation over the Ni/CeO2-S catalyst, the conversion of CO and selectivity to CH4 at 350 ℃ reach 99.19% and 88.88%, respectively. After 10 h thermal stability test, the Ni/CeO2-S catalyst displays lowest carbon deposit (2.5%); the selectivity to CH4 over the Ni/CeO2-S catalyst remains above 80%, which is 1.3 times of that over Ni/CeO2-F and 17.6 times of that over Ni/CeO2-P. The excellent catalytic performance of Ni/CeO2-S may be ascribed to that CeO2-S support has large surface area and mainly exposes the [111] crystal plane with a large amount of oxygen vacancies, which can enhance the interaction between the support and the active center and alleviate the carbon deposition.
Abstract: Ni/KIT-6 catalysts modified by Mg, Ce, V and La for CO2 methanation were prepared by co-impregnation method.The catalysts were characterized by N2 absorption-desorption, XRD, H2-TPD and TEM.The effects of different promoters on structure and properties of Ni/KIT-6 catalysts were investigated. The results show that the dispersity of Ni and promoters are very high. The dispersion of Ni particles depends primarily on the confinement effect of the well-ordered mesoporous structure of KIT-6, and is not affected by the addition of metal promoters. The addition of promoters does not affect the surface morphology of Ni/KIT-6 catalyst, but has effects on the difficulty and reduction degree of Ni reduction. Among the metal promoters studied, V addition makes the reduction of NiO in the catalyst easily and results in a high reduction degree. The oxide of V can change the reaction mechanism of CO2 methanation, resulting in the best methanation performance. Compared with the unmodified catalyst, the catalyst modified by V makes the conversion of CO2 and the selectivity of CH4 increase by 3.7% and 11.6% respectively. The selectivity of CH4 is 100%.
Abstract: SiO2 and La2O3-SiO2 were synthesized via sol-gel method and used as support to prepared Rh-La or Rh doped catalysts by iso-volumic impregnation. Effects of doping mode of La on the catalytic performance of Rh/SiO2 for CO hydrogenation are investigated detailedly. The results reveal that the addition of La can improve the dispersion of Rh and increase Rh+ centers, which can effectively inhibit the formation of CO2 and improve the selectivity of oxygenates. Furthermore, the doping mode of La can affect the interaction between La and Rh. A strong La-Rh interaction is achieved over the 2Rh-5La2O3/SiO2 catalyst prepared by co-impregnation of Rh and La with SiO2 support. The strong interaction between La and Rh can efficiently weaken the Rh-CO bonds and enhance the CO insertion reaction in the reaction process, which makes the product dominated by C2+ oxygenates. The 2Rh/5La2O3-SiO2 catalyst prepared via La2O3-SiO2 composite support exhibits a weak La-Rh interaction, and methanol, ethanol and other low-carbon alcohols are obtained as the main products.
Abstract: Co-based catalyst was prepared by impregnation method with SiO2 as the support. The effects of glucose and Pd on the structure and property of the catalysts were characterized by N2 low-temperature adsorption, XRD, SEM and H2-TPR. The reactive performance of the catalysts in F-T synthesis was evaluated in a fixed-bed reactor. The shape of Co3O4 crystal particle was changed by the added glucose and Pd. The addition of glucose increased the dispersion of Co3O4 species, and the addition of Pd promoted the reduction of the catalyst although its dose was only 0.0125%. The combination of glucose and Pd increased the dispersion and reduction of Co3O4 species on the catalysts simultaneously. As the result, both of the CO conversion and the selectivity of C5+ hydrocarbons increased in F-T synthesis reaction.
Abstract: Surface silicon-rich ZSM-5 zeolites were prepared by surface chemical modification; their pore structure and acid properties were characterized by XRD, nitrogen sorption, TEM, NH3-TPD and Py-FTIR spectroscopy. The catalytic performance of modified ZSM-5 zeolites in the conversion of methanol to p-xylene and lower olefins was investigated. The results show that the introduction of Zn in ZSM-5 can change part of the strong acid sites into the medium ones and increase the Zn-Lewis acid sites with dehydrogenation capacity, which can enhance the selectivity to ethene and propene. The modification with Mg can not only adjust the pore shape selectivity, but also increase the amount of Lewis acid sites, which is beneficial to the formation of p-xylene. Through multiple silicon depositions from different silicon sources, SiO2 is uniformly deposited on the outer surface of modified ZSM-5 catalysts, which can modulate the acid properties and pore structure and thereby further improve the selectivity to p-xylene and ethene and propene. By using these modification approaches, the selectivity to p-xylene and ethene and propene reaches 61%, with 87.1% of p-xylene in the xylenes product, 97.8% of ethene in C2 hydrocarbons, and 90.6% of propene in C3 hydrocarbons.
Abstract: Four kinds of supported ionic liquid catalysts were prepared by encapsulation of ionic liquids within the nanocage of KIT-5 and were used in the synthesis of polyoxymethylene dimethyl ether (PODEn) from dimethoxymethane and trioxane; the effects of conditional parameters on the conversion of trioxane and the selectivity to targeted PODE3-5 were systematically investigated. The results show that the optimum reaction parameters for the synthesis of polyoxymethylene dimethyl ether were: reaction time of 2 h, 100 ℃, dimethoxymethane to trioxane molar ratio of 1.5, and catalyst content of 3%. Under the optimum conditions, the encapsulated catalysts are efficient in the synthesis of polyoxymethylene dimethyl ether, with a similar catalytic activity to the homogeneous counterparts. Moreover, the encapsulated catalysts can be reused several times without remarkable loss of activity and product selectivity, which makes it a promising catalyst for practical applications.
Supervisor：Chinese Academy of Sciences
Sponsors by：Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences Chinese Chemical Society
