Catalytic combustion of propane over mixed oxides derived from CuxMg3−xAl hydrotalcites

Cu-based mixed oxides (CuxMg3−xAlO-800s, x = 0, 0.5, 1.0, 1.5, 2.0 and 3.0) were prepared by calcinations of corresponding CuxMg3−xAl ternary hydrotalcites (CuxMg3−xAl-HTLCs) at 800 °C and used for catalytic combustion of propane. The CuxMg3−xAl ternary hydrotalcites and derived combustion catalysts were well characterized to investigate the dependence of the performance of propane catalytic combustion with their structure and components. The results showed that Cu can replace Mg in a wide range of Cu/Mg ratios to form CuxMg3−xAl-HTLCs with the unique layered structure of hydrotalcite, though the Cu substitution significantly deteriorates the thermal stability of the CuxMg3−xAl-HTLCs. It was found that calcinations at 800 °C completely transformed the CuxMg3−xAl-HTLCs to CuxMg3−xAlO-800 mixed oxides, containing spinel, periclase and tenorite oxide phases. The TPR results revealed those catalysts derived from hydrotalcites were easier to be reduced than the simply mixed oxides, this was due to the strong interactions among the components existing in the CuxMg3−xAlO-800 materials. The CuxMg3−xAlO-800 catalysts exhibit superior catalytic activity in propane combustion to Pd/Al2O3 and the mechanically mixed oxides. The excellent activities of the CuxMg3−xAlO-800 were attributed to the strong interaction among the component oxides as observed by the XRD, TG-DSC and TPR characterizations.