摘要：In recent years, coal and biomass synthetic natural gas have become a hot issue. The traditional natural gas synthesis route is based on the conversion of carbon raw materials, through the catalytic conversion reaction of methanation, to synthesize natural gas. Among all the active components of methanation catalysts, nickel-based catalysts have been widely used for their high reactivity, methane selectivity and low cost. However, nickel-based catalysts are prone to form nickel carbonyl at low temperature (200-300T) and low hydrogen-carbon ratio, which results in nickel particle sintering. It is possible to produce high molecular carbon at 500 degrees centigrade and decrease in activity at 500 degree Celsius. This may be due to the thermal sintering of the carrier, the formation of carbon deposition, or the growth of nickel crystals due to the migration and reduction of particles. In order to further improve the high temperature stability and sulfur tolerance of the catalyst, a series of xNi/TiO_2 and 20Ni/xMn-TiO_2 catalyst were prepared by impregnation method and the effect of Ni and Mn loading on the catalytic performance for CO Methanation was studied respectively. XRD, SEM, TG/DTG and evaluation of activity were used to examine the catalysts. A fixed bed tubular reactor is used as the catalyst evaluation device. The reactor was heated in three stages. The bed temperature was measured by a thermocouple extending into the bed. Spectrometer (Agilent-GC7890B) analysis, thermal conductivity tank detector (TCD) analysis of CH_4, CO_2, CO, H_2. Hydrogen flame ionization detector (FID) was used to analyze other alkanes in the product. The activity of the catalyst was evaluated and characterized by XRD, SEM and TG/DTG. The results show that the activity of 20Ni/TiO_2 is the highest, up to 99%, in the xNi/TiO_2, while the Ni loading affect xNi/TiO_2 activity is not the main factor; With 20 Ni/TiO_2 catalysts for the further study, add Mn in the xNi/TiO_2 catalyst will improve its CH_4 selectivity and temperature interval. Characterization analysis found that adding Mn will increase the degree of dispersion of active components. The reduction method and temperature test of 20Ni/8Mn-TiO_2 shows that the catalyst reduced under 4000C TPR performance better.
