Disassembly-reassembly-phosphating strategy to fabricate hydrothermally-stable hierarchical P@ZSM-5 zeolite for efficient methanol-to-propylene

Available hierarchization and phosphorization of ZSM-5 zeolite as one of methanol-to-propylene (MTP) catalysts have improved reactive stability and propylene selectivity, but are subjected to the problems of poor phosphorus stabilization efficiency and inhomogeneous dispersion. Herein, we fabricate a series of hierarchical P@ZSM-5 zeolites via one-step disassembly-reassembly-phosphating strategy of ZSM-5 zeolite using successfully self-created asymmetric quaternary phosphonium hydroxides and elucidate the mechanism of mesoporous formation and the interaction of phosphorus with framework aluminum. Delightfully, reconstructively tetracoordinated P IV -O-Al IV structure endows excellent hydrothermal and Brønsted acid stability of hierarchical P@ZSM-5 zeolites. The MTP tests show that the P@ZSM-5(TBuCP) catalyst prepared by disassembly-reassembly-phosphating of tributylhexadecylphosphine hydroxide (TBuCPOH) exhibits superior propylene selectivity (48.9 %) and remarkedly long lifetime (32.5 h, WHSV=6h −1 ). Such enviable MTP performance is benefited from the join hands of the zeolitic hierarchization and suitable Brønsted acid strength conferred by its phosphorus-aluminum interaction that are conducive to olefinic cycle process. These findings afford value-filled opportunities in novel MTP catalysts with high reactive stability and propylene selectivity, and the understandings for phosphorus-zeolite chemistry.