Aiming at deep desulfurization of gasoline,three amphiphilic catalysts [C18H37N(CH3)3]3+x [PMo12-xVxO40](x=1,2,or 3) were prepared and characterized.The amphiphilic vanadium(V)-substituted polyoxometalates were dissolved in water-immiscible ionic liquid([Bmim]PF6),forming a H2O2-in-[Bmim]PF6 emulsion desulfurization system with 30 m% H2O2 serving as the oxidant.The catalytic oxidation of sulfur-containing model oil has been studied in detail under various reaction conditions using this system.The ionic liquid emulsion system showed high catalytic oxidative activity in the treatment of commodity gasoline.Furthermore,the mechanism of catalytic oxidative desulfurization was also elaborated.
Effects of hydrochloride acid dealumination of mordenite(MOR) catalysts for the synthesis of 1-phenyl-1-xylyl ethane(PXE) were investigated. The structure and acidity of catalysts were characterized by XRD, BET, XRF, FT-IR, 27Al NMR and NH3-TPD techniques. The catalytic performance of the acid-treated MOR zeolites was studied through using the alkylation of o-xylene with styrene. The test results showed that the strength of remaining Br?nsted acid sites increased despite the reduction of total number of acid sites after dealumination, and the micropores of HMOR were slightly enlarged coupled with the formation of secondary mesopores. Additionally, the modified HMOR zeolites showed longer catalyst life with the styrene conversion rate retained. Among the catalysts employed in this study, the modified mordenite that was dealuminated by HCl(2 mol/L) could be used repeatedly without significant loss of activity and selectivity during six catalytic runs, which have been ascribed to its specific acidity and structural properties.
Kong JieSheng XiaoliZhou YumingZhou ShijianZhang Zewu
Solid-state grinding is a simple and effective method to introduce guest species into the channels of microporous materials through filling.The structure and the surface acidity of the materials were obtained from BET isotherms and NH3-TPD,respectively.XRD,UV-vis,UV diffuse-reflectance,and TEM were used to characterize the phases,and the morphology,respectively.The clustered layers of MgO-Al2O3phases were formed in the internal pore surface and were highly dispersed inside the channels of the ZSM-5 host.So the volume of MgO-Al2O3/ZSM-5 composite was larger than the ZSM-5 zeolite itself and some mesoporous channels appeared when Mg/Al species entered the channels.Meanwhile,new acid sites emerged in MgO-Al2O3/ZSM-5 composite and the acid amount of the sample changed.The improved Pt dispersion and the increased acid content would cause the increase of propane conversion and the modification of selectivity during the reaction.
Zhou ShijianZhouYumingSheng XiaoliZhangYiweiZhang ZewuShi JunjunKong Jie
The effects of the sequence for impregnation of metal precursors on the performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation to propene were studied in this paper.Some methods such as XRD,TPDA,BET,H2-TPR,XPS,ICP,TEM and hydrogen chemisorption were used to characterize the catalysts.The structure of ZSM-5 zeolite was not destroyed by the introduction of metal components.Meanwhile the different impregnation sequence of metal precursors could affect the behavior of Sn4+species entering the ZSM-5 channel,and the interaction between platinum and tin species,as well as the degree for reduction of Pt and Sn components.As a result,the prepared catalysts exhibited different reaction activity and selectivity.Compared with the co-impregnation treated catalyst,the catalysts prepared by the sequential impregnation method showed better catalytic activity in propane dehydrogenation,especially the one prepared through impregnation with tin precursor at first.Finally,a model for the effect of impregnation sequence on the distribution of Pt and Sn species in PtSnNa/ZSM-5 catalyst was proposed.
Liu HuiZhou YumingZhang YiweiSheng XiaoliZhang ZewuZhou Shijiang
