Gold/Mg-Al mixed oxides catalysts for oxidative esterification of methacrolein: Effects of support size and composition on gold loading

Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation. Effects of the support particle size, concentration of HAuCl4 solution and Mg/Al ratio on gold loading and catalytic properties are investigated. The catalysts are characterized by CO2-TPD, EDS, XPS, STEM and XRD techniques. Catalysts with smaller support particle size show more uniform gold distribution and higher gold dispersion, resulting in a higher catalytic performance, and the uniformity of gold and the activity of the catalysts with larger support particle size can be improved by decreasing the concentration of HAuCl4 solution. The Mg/Al molar ratio has significant effect on the uniformity of gold and the activity of the catalyst, and the optimum Mg/Al molar ratio is 0.1–0.2. This study underlines the importance of engineering support particle size, concentration of HAuCl4 solution and density of adsorption sites for efficient gold loading on support by impregnation.