Role of complex equilibrium in the shape-selective performances of MgO/MCM-22 catalysts prepared by complexing impregnation

• Effects of complex equilibrium on the shape-selectivity of MgO/MCM-22 catalysts
• The complex equilibrium was shifted by the addition of HCl.
• Improvement in shape-selectivity of MgO/MCM-22 was achieved by addition of HCl.

The role of complex equilibrium in the shape-selectivity of the MgO/MCM-22 catalysts prepared by complexing impregnation was investigated. The presence of hydrochloric acid during the complexing impregnation process resulted in a significant improvement of selectivity for p-xylene production by toluene methylation with dimethyl carbonate over MgO/MCM-22 catalysts. The dramatic performance was ascribed to the designated shifting of the complex equilibrium of malonic acid and Mg2 +, which may alter the coverage of acidic sites on the external surface of zeolite, adjust the pore size of zeolite, and therefore affect the shape-selective performances of the catalysts.

Figure optionsDownload as PowerPoint slide