Modification of Cs/SiO2 with Zr element through sol–gel method for production of methyl methacrylate via one-step aldol condensation

Development of effective cesium-based catalyst is important for methyl methacrylate (MMA) production via one-step aldol reaction. Herein, a kind of Cs/Zr-SiO₂ catalyst was prepared by sol–gel method and the acid-base properties and their balance could be controllably regulated. The influence of catalyst preparation conditions including Si/Zr ratio and water content on the structure and acid-base properties of Cs/Zr-SiO₂ was demonstrated, which consequentially affected catalytic performance. The formation of Si-O-Zr and Cs-O-Si structure was identified as the dominant Lewis acid and base sites and the acid site density can be enhanced by 1-fold when using sol–gel method. In addition, the MP conversion could reach 37 % with MMA selectivity of 85 % at the optimal condition. Kinetic studies revealed that the activation barrier on the modified 10Cs/Zr-SiO₂ exhibited the lowest activation energy of 110.9 kJ/mol. Besides, the initial catalytic activity could still maintain after 800 h recycling, with single-pass life of 160 h.