Dual-site engineering of Ga-modified HZSM-5 towards efficient propane aromatization

Light alkane aromatization represents a pivotal catalytic process for valorizing abundant light alkanes into high-value aromatics, holding significant industrial promise. Herein, a series of Ga-HZSM-5 catalysts were synthesized by the hydrothermal method. The effects of Ga content and Si/Al ratio on the catalytic performance of propane aromatization over Ga-HZSM-5 were investigated to discern the structure-activity relationship, reaction pathway, and coke formation. The optimized 1%Ga-HZSM-5(50) catalyst exhibited superior performance, with propane conversion and BTX formation showing a volcano-shaped trend with increasing Ga content. Conversely, for a fixed Ga loading, aromatization performance was enhanced with decreasing Si/Al ratio, with 1%Ga-HZSM-5(25) delivering the highest aromatization activity. A positive correlation was identified between catalytic activity and Lewis acid density, underscoring the role of Lewis sites in facilitating propane dehydrogenation and subsequent BTX formation. Furthermore, TG and TPO analyses revealed that the deposited coke in Ga-HZSM-5 was predominantly highly graphitized, which could not be removed by the air-regeneration treatment under reaction temperature.