Synthesis And Characterization Of Ni-CeO₂ For Reverse Water Gas Shift Reaction

Various kinds of chemical fixation have been proposed to solve global warming caused by emitted CO2. Among various methods, conversion of CO2 to CO by catalytic reaction has been recognized as one of the most promising processes for CO2 utilization. The reverse water gas shift (RWGS) reaction is one of the available methods for production of CO using CO2. Nowdays, many catalysts are in limitation for stabilitiy. Morerover, there are lack in conversion and selectivity of catalysts, So, it is important for carbon dioxide resourceful using and producing of energy sourse though studying and exploituring of high performance and steady catalysts for RWGS. Because nickel catalyst has predominance in good catalytic activity, stability and low price, structure and performance nickel, catalysts will be reviewed in RWGS.The paper exert testing and characterization of activity,XRD,BET,TPR and TG/DTA, The Ni/CeO2 catalysts were prepared by co-precipitation method with nickel nitrate and cerium nitrate as precursors , which are studied means, process and controning condition. It is studied many factors such as the content of active component, aging time, calcination temperature, carrier, preparation method and space velocity in order to know the effect of these factors on the structure and performance of Ni-Ce oxides. The main results are as follows:Ni/CeO2 catalyst made by co-precipitation method show best performance with the condition of aging for 24h, 1wt%Ni/CeO2, calcining; the precipitators are sodium hydroxide and sodium carbonate, and the mixing ratio is 1:1. The catalysts show better activity and selectivity after H2/N2 pretreatment and reducing temperature 600℃. The stability test is carried out for 10h over 1wt%Ni/CeO2 catalysts. The result indicates The catalyst shows better activity and selectivity.XRD results indicate that the catalysts are composed of nickel ions in ceria lattice, highly dispersed Ni and bulk Ni. At low nickel content (≤1 wt.% Ni), nickel exists mostly as nickel ions in ceria lattice and as highly dispersed Ni, At high nickel content (≥5 wt.% Ni), nickel exists mostly as nickel ions in ceria lattice, as highly dispersed Ni and bulk Ni. TPR results indicate that three steps reduce the nickel, which is reduced by NiO in ceria lattice, highly dispersed NiO and bulk NiO. It is supposed that the nickel ions in ceria lattice and highly dispersed Ni are key active components for RWGS, bulk Ni is key active component for methanation of CO2.