A novel, shape-selective H-MCM-22/MCM-41 composite catalyst: Synthesis, characterization and catalytic performance

A novel, shape-selective H-MCM-22/MCM-41 composite catalyst is synthesized for the first time by overgrowing MCM-41 over the external surface of H-MCM-22. Results of FT-IR characterization with 2,4-dimethylquinoline adsorption indicate that the Brønsted acidic sites of H-MCM-22 located on the external surface can virtually be completely covered by the generated layer of MCM-41. When applied to the synthesis of p-xylene by the alkylation of toluene with dimethyl carbonate, the H-MCM-22/MCM-41 composite exhibits significant enhancement in p-xylene selectivity, which can be ascribed to the decrease in the number of external Brønsted acid sites of the composite.

Graphical AbstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch Highlights►MCM-41 layer overgrows on the external surface of H-MCM-22. ►The external Brønsted acid sites of H-MCM-22 are covered by MCM-41. ►High selectivity for para-xylene is obtained over the H-MCM-22/MCM-41composite.