Sol–gel citrate procedure to synthesize Ag/Co3O4 catalysts with enhanced activity for propane catalytic combustion

The Co3O4 and Ag/Co3O4 catalysts with varying content of Ag were fabricated via sol–gel citrate procedure, which were used for propane total oxidation. First, Ag+ and/or Co2+ ions coordinate with citric acid to form silver and/or cobalt citrate complex, then calcined to produce Ag/Co3O4 catalysts. Among all the catalysts, the 6%Ag/Co3O4 sample exhibited a much higher catalytic performance, with 90% conversion of propane at only 228 °C, which was 24 °C lower than that of pure Co3O4 catalyst. Characterization results showed that the introduction of Ag decreased the particle size of Co3O4, increased the Co3+/(Co3++Co2+) ratio and surface adsorption oxygen content, and enhanced the low-temperature reducibility, which resulted in the outstanding catalytic performance.