摘要: In this work, series of Ni/γ-Al2O3 catalysts with or without Cu and Mo components were prepared, characterized and tested for the hydrodeoxygenation of fatty acid methyl esters (FAME) to hydrocarbons. The effects of Cu and Mo loading, impregnation sequence with sequential impregnation and co-impregnation involved and reaction conditions on catalytic performance were investigated. According to the TG data, the spent 20Ni-6Cu/γ-Al2O3 catalyst gives less weight loss than the spent 20Ni/γ-Al2O3 catalyst, which indicates that the addition of copper inhibits the carbon deposits behavior on catalyst surface during reaction. For 20Ni-6Cu/γ-Al2O3 and 20Ni-6Cu-nMo/γ-Al2O3(n=2, 5, 8 and 12) catalysts, NH3-TPD analysis shows that the addition of molybdenum phase has significant impact on the acid sites of γ-Al2O3. When the loading of molybdenum is 5%, a new acid site is observed corresponding to the medium strength acid site. The Cu and Mo modified catalysts demonstrate better catalytic performance than Ni/γ-Al2O3 catalysts. Based on XPS results, Cu in the catalysts exists in the Cu2+ and Mo in the catalysts has two states:Mo4+ and Mo6+, and different impregnation sequences may influence the actual element composition of active phase on the surface of catalysts. In addition, the conversion of FAME and yield of alkane are related to the catalysts prepared with different impregnation sequence. Among all the catalysts, the trimetallic 20Ni-6Cu-5Mo/γ-Al2O3 prepared by sequential impregnation (the former Ni and Cu impregnation, the latter Mo impregnation) exhibits optimal catalytic performance. Under appropriate reaction conditions 350℃, 2.5 MPa, WSHV=2.0 h-1, H2/oil ratio=1250 mL/mL, the conversion of FAME and yield of alkane are 98.4% and 94.2%.
摘要: The essential role of Co on the MoS2 catalyst in selective hydrodesulfurization (HDS) of FCC gasoline was investigated with ammonium tetrathiomolybdate supported on alumina modified with various amount of Co sulfide. According to the data obtained by XRD, HRTEM, XPS, H2-TPR and Py-FTIR analysis, the Co species could significantly affect the microstructure and composition proportion of the active phase, and thus induced the enormous differences in catalytic properties. The evaluation results demonstrated that the Co atoms tending to form the CoMoS phase as Co/Mo(atomic ratio) < 0.2 could greatly improve the HDS activity, but slightly improve the hydrogenation (HYD) activity of olefins. The spillover hydrogen produced by the formation of Co9S8 phase as 0.2 < Co/Mo(atomic ratio) < 0.6 greatly improved the HDS activity, but showed almost no effect on the HYD of olefins. The excess Co could inevitably form some large size Co9S8 phase as Co/Mo(atomic ratio) > 0.6, which would hinder the mutual contact of the reactants and the active sites, and thus lead to the decrease of the HDS activity and selectivity. The obtained results were useful for developing highly effective hydrotreating catalyst.
摘要: Amorphous alloy NiP and its carbon composite catalysts NiP/C and NiP/reduced graphene oxide (RGO) were successfully one-pot synthesized using NaH2PO2 and NiSO4 as phosphorus and nickel source, respectively. The electrocatalysts were characterized with transmission electron microscope (TEM), X-ray diffraction spectrometer (XRD), inductively coupled plasma analysis (ICP) and thermogravimetric analysis (TG), respectively. The hydrogen evolution reactions (HER) performance of the electrocatalysts was evaluated with a linear sweep voltammetry method in both acidic and alkaline solution. Among them, NiP/RGO elctrocatalyst exhibited 89.0 mV onset overpotential and Tafel slope 135.1 mV/decade in acidic solution, as well as 116.1 mV onset overpotential and Tafel slope 122.4 mV/decade in alkaline solution with excellent long-term stability. Results indicated that the NiP/RGO was a very active catalyst.