Catalytic Methanation of Carbon Dioxide by Active Oxygen Material CexZr1−xO2 Supported NiCo Bimetallic Nanocatalysts

Abstract

A series of active oxygen material CexZr1−xO2‐supported NiCo bimetallic nanosized catalysts were prepared by coprecipitation method, which is simple and fit for industrial use with lower cost than other methods. The effect of CeO2/ZrO2 mole ratio, Co metal addition, and PEG‐6000 addition were investigated. The catalysts were characterized through X‐ray diffraction, H2 thermal‐programmed reduction, N2 adsorption, Raman spectroscopy, CO pulse chemisorption, X‐ray photoelectron spectroscopy, oxygen storage capacity, and transmission electron microscopy‐energy dispersive X‐ray analysis. Modifications of the structural and redox properties of these materials were evaluated in relation to their catalytic performances. Particularly, the relationship between the active oxygen sites of the catalysts and their catalytic performances was investigated. The interaction between active metals (Ni and Co) and CexZr1−xO2 support was found to be very important for catalytic performance. The active oxygen site of CexZr1−xO2 can considerably improve catalytic performance. Appropriate Co metal addition also remarkably enhanced the catalytic stability and activity. Moreover, PEG‐6000 addition can improve the Brunauer–Emmett–Teller surface area and active metal dispersion of catalysts to improve their performances. The nanosized catalyst 15 wt % Ni‐5 wt % Co/Ce0.25Zr0.75O2 prepared by adding 5 wt % PEG‐6000 achieved almost 85% CO2 conversion and 98% selectivity to methane at 280°C when the gas hourly space velocity was 10,000 h−1. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2567–2576, 2013