Sol–gel citrate procedure to synthesize Ag/Co 3 O 4 catalysts with enhanced activity for propane catalytic combustion

The Co 3 O 4 and Ag/Co 3 O 4 catalysts with varying content of Ag were fabricated via sol–gel citrate procedure, which were used for propane total oxidation. First, Ag + and/or Co 2+ ions coordinate with citric acid to form silver and/or cobalt citrate complex, then calcined to produce Ag/Co 3 O 4 catalysts. Among all the catalysts, the 6%Ag/Co 3 O 4 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 Co 3 O 4 catalyst. Characterization results showed that the introduction of Ag decreased the particle size of Co 3 O 4 , increased the Co 3+ /(Co 3+ +Co 2+ ) ratio and surface adsorption oxygen content, and enhanced the low-temperature reducibility, which resulted in the outstanding catalytic performance. Graphic abstract