Organosilane surfactant-directed synthesis of hierarchical mordenite with enhanced catalytic performance in the alkylation of benzene with 1-dodecene†
Abstract
To improve the stability of mordenite (MOR) in the alkylation of benzene with long chain olefin, hierarchical MOR zeolites were synthesized by using organosilane surfactant [3-(trimethoxysilyl)propyl]octadecyldimethyl-ammonium chloride (TPOAC) as the mesopore structure-directing agent. Our findings reveal that the crystal size, hierarchical structure, and acidic properties of the mesoporous MOR zeolites are significantly influenced by the TPOAC/SiO2 molar ratio in the synthesis gel. Moreover, the hierarchical MOR zeolite synthesized under the optimized synthesis conditions presented the pure phase of the MOR framework and uniform mesoporous distribution. More importantly, the catalytic performance evaluated by the alkylation of benzene with 1-dodecene indicates that the optimal mesoporous MOR zeolite shows improved stability and comparable selectivity of 2-phenyl alkane (2-LAB) around 80% compared to the conventional sole microporous MOR zeolite. The improved stability of the mesoporous MOR zeolite can be attributed to the enhanced diffusivity of long chain linear alkylbenzenes and oligomers due to interconnected meso-/microporosity in the MOR.