The promotional effects of Zr on the structure, reduction, carburization and catalytic behavior of precipitated iron-based Fischer-Tropsch synthesis （FTS） catalysts were investigated. The catalysts were characterize...The promotional effects of Zr on the structure, reduction, carburization and catalytic behavior of precipitated iron-based Fischer-Tropsch synthesis （FTS） catalysts were investigated. The catalysts were characterized by N2 physisorption, temperature-programmed reduction （TPR）, and M6ssbauer effect spectroscopy （MES） techniques. As revealed by N2 physisorption, Zr decreased the BET surface area and pore volume of the catalyst. The results of TPR and MES show that Zr suppresses the reduction and carburization of Fe catalysts because of the interaction between Fe and Zr. The FTS reaction results indicate that Zr decreases the FTS activity of Fe catalysts but improves the catalysts＇ stability. In addition, Zr promoter restraines the formation of light hydrocarbons （methane and C2-C4） and shifts the production distribution to the heavy hydrocarbons.展开更多
Effects of vanadium on light olefins selectivity of FCC catalysts were investigated with vanadium having different oxidation numbers （hereinafter abbreviated as Oxnum）. Molecular modeling studies showed that vanadiu...Effects of vanadium on light olefins selectivity of FCC catalysts were investigated with vanadium having different oxidation numbers （hereinafter abbreviated as Oxnum）. Molecular modeling studies showed that vanadium with low Oxnum could affect the chemical conversion of large-size hydrocarbon molecules. However, the vanadium deposited on equilibrium catalyst bad high Oxnum because of the oxidation reaction taking place in the regenerator, so an activation method to reduce vanadium Oxnum named ＂selective activation＂ was introduced. It was proved by means of Electron Paramagnetic Resonance （EPR） and Temperature-Programmed Reduction （TPR） methods that the vanadium Oxnum was decreased, when the catalyst was activated. The molecular modeling studies are consistent well with the lab evaluation results. The light olefins selectivity of activated equilibrium catalysts was better than that achieved by the inactivated catalysts. Similar results were observed with the lab vanadium-contaminated catalyst. The light olefins selectivity of the catalyst was optimized when the vanadium Oxnum was close to 2 （VO）.展开更多
PtSnNaGa/ZSM-5 catalysts with different contents of Ga were prepared and characterized by X-ray diffraction (XRD), nitrogen adsorption, hydrogen chemisorption, ammonia temperature-programmed desorption (NH3-TPD), hydr...PtSnNaGa/ZSM-5 catalysts with different contents of Ga were prepared and characterized by X-ray diffraction (XRD), nitrogen adsorption, hydrogen chemisorption, ammonia temperature-programmed desorption (NH3-TPD), hydrogen temperature-programmed reduction (H2-TPR), and temperature-programmed oxidation (TPO) techniques. The performances of these catalysts for propane dehydrogenation were investigated. The test results indicated that the addition of Ga not only could improve the catalytic stability and propene selectivity, but also could effectively prevent the catalysts from coking. It was found that the PtSnNaGa(0.5 m%)/ZSM-5 catalyst exhibited the best performance in terms of propene selectivity and propane conversion. The high catalytic performance was most probably attributed to the presence of Ga that could strength- en the interaction between metals and the support to stabilize the catalytic active sites.展开更多
文摘The promotional effects of Zr on the structure, reduction, carburization and catalytic behavior of precipitated iron-based Fischer-Tropsch synthesis （FTS） catalysts were investigated. The catalysts were characterized by N2 physisorption, temperature-programmed reduction （TPR）, and M6ssbauer effect spectroscopy （MES） techniques. As revealed by N2 physisorption, Zr decreased the BET surface area and pore volume of the catalyst. The results of TPR and MES show that Zr suppresses the reduction and carburization of Fe catalysts because of the interaction between Fe and Zr. The FTS reaction results indicate that Zr decreases the FTS activity of Fe catalysts but improves the catalysts＇ stability. In addition, Zr promoter restraines the formation of light hydrocarbons （methane and C2-C4） and shifts the production distribution to the heavy hydrocarbons.
文摘Effects of vanadium on light olefins selectivity of FCC catalysts were investigated with vanadium having different oxidation numbers （hereinafter abbreviated as Oxnum）. Molecular modeling studies showed that vanadium with low Oxnum could affect the chemical conversion of large-size hydrocarbon molecules. However, the vanadium deposited on equilibrium catalyst bad high Oxnum because of the oxidation reaction taking place in the regenerator, so an activation method to reduce vanadium Oxnum named ＂selective activation＂ was introduced. It was proved by means of Electron Paramagnetic Resonance （EPR） and Temperature-Programmed Reduction （TPR） methods that the vanadium Oxnum was decreased, when the catalyst was activated. The molecular modeling studies are consistent well with the lab evaluation results. The light olefins selectivity of activated equilibrium catalysts was better than that achieved by the inactivated catalysts. Similar results were observed with the lab vanadium-contaminated catalyst. The light olefins selectivity of the catalyst was optimized when the vanadium Oxnum was close to 2 （VO）.
基金supports provided by the Production and Research Prospective Joint Research Project (BY2009153)the Science and Technology Support Program (BE2008129)of jiansu Province of chinathe National Natural Science Foundation of China(50873026)
文摘PtSnNaGa/ZSM-5 catalysts with different contents of Ga were prepared and characterized by X-ray diffraction (XRD), nitrogen adsorption, hydrogen chemisorption, ammonia temperature-programmed desorption (NH3-TPD), hydrogen temperature-programmed reduction (H2-TPR), and temperature-programmed oxidation (TPO) techniques. The performances of these catalysts for propane dehydrogenation were investigated. The test results indicated that the addition of Ga not only could improve the catalytic stability and propene selectivity, but also could effectively prevent the catalysts from coking. It was found that the PtSnNaGa(0.5 m%)/ZSM-5 catalyst exhibited the best performance in terms of propene selectivity and propane conversion. The high catalytic performance was most probably attributed to the presence of Ga that could strength- en the interaction between metals and the support to stabilize the catalytic active sites.
