Synthesis of Hierarchical ZSM-5 Zeolite Using a Novel Organosiloxane for 1,2,4-Trimethylbenzene Isomerization Catalysis

A novel organosiloxane (KHPA) was synthesized using 3-glycidyloxypropyltrimethoxysilane (GPTMS) and propylamine as raw materials. The effects of KHPA addition on the physicochemical properties of hierarchical ZSM-5 zeolite were investigated. The synthesized zeolite samples were systematically characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), low-temperature N 2 adsorption-desorption, x-ray fluorescence (XRF), thermogravimetric (TG) analysis, and ammonia temperature-programmed desorption (NH 3 -TPD). The results indicated that the addition of KHPA into the synthesis system hindered the growth of zeolite crystals, leading to the formation of abundant inter-crystalline mesopores. When the KHPA addition amount was 6 g, the synthesized sample exhibited the highest external surface area (303.5 m 2 /g) and mesopore volume (0.38 cm 3 /g), and the SEM and TEM images revealed intergranular mesopores formed by the stacking of nanoparticles. Furthermore, the Z-KHPA-6 sample exhibited optimal catalytic performance in the trimethylbenzene isomerization reaction, demonstrating a 1,2,4-trimethylbenzene mass conversion of 36.26%, 1,3,5-trimethylbenzene mass yield of 22.61%, and 1,3,5-trimethylbenzene selectivity of 62.36%. Graphical Using GPTMS and propylamine as raw materials, a novel organosiloxane KHPA was synthesized as a mesoporous template. A hierarchically porous ZSM-5 zeolite was successfully prepared via the hydrothermal method. The introduction of KHPA into the synthesis system impeded the crystal growth of the zeolite, resulting in abundant intercrystalline mesopores. This unique pore structure effectively enhanced the isomerization of 1,2,4-trimethylbenzene, significantly improving catalytic efficiency and reaction selectivity.