Hierarchically structured SAPO-5 molecular sieve catalysts with tailored mesoporosity for alkylation reaction

摘要

Hierarchically structured SAPO-5 molecular sieve was synthesized by microwave-assisted ionothermal method in eutectic mixture solvent. Their porous texture and acid properties were characterized by nitrogen physisorption, SEM, TEM and NH3-TPD. The results show that the mesoporous volume of SAPO-5 can be tuned via simply varying the degree of supersaturation, the type of mineralizer or replacing partly succinic acid with sebacic acid. A lower degree of supersaturation and using ammonium fluoride as a mineralizer favor the synthesis of SAPO-5 with large mesoporous volume. Notably, the introduction of sebacic acid can lead to three-level micro-meso-macroporous structure (sample C1). Five typical samples were selected as catalysts and tested in the alkylation of benzene with benzyl alcohol. Among all catalysts, the sample C1, whose aspect ratio is the lowest, exhibited the best catalytic activity, giving a 91 % benzyl alcohol conversion. The diffraction peak intensity ratio of I-002/I-100 was proposed to be a good indicator in fabricating a highly active SAPO-5 catalyst for this reaction.