Preparation of Biscuit-Like SO²⁻₄/ZrO₂ Catalyst for Alkylation of o-Xylene with Styrene

We present here a facile synthesis of SO2-4/ZrO2 solid superacid by impregnating the biscuit-like mesoporous ZrO2 nanoparticles prepared by an emulsion combustion method directly into H2SO4 solution. The obtained solid acid catalyst was characterized by means of X-ray powder diffraction, transmission and scanning electron microscopy, thermogravimetry, Brunner-Emmet-Teller measurement, and infrared analysis. Its catalytic performance was examined by alkylation of o-xylene with styrene. The optimal catalytic formulation, obtained from the investigation of experimental conditions, was determined to be 5 wt% of catalyst loading with initial o-xylene/styrene molar ratio of 5 under reaction temperature at 120 °C for 120 min, achieving a 100% styrene conversion and a 93.3% 1-phenyl-1-xylyl ethane selectivity. The biscuit-like SO2−4/ZrO2 solid acid exhibited high catalytic activity and selectivity and excellent structural stability. This synthetic strategy for preparing the mesoporous SO2−4 promoted ZrO2 solid superacid catalyst is generalized and expected to be applied to other metal oxides.