Higher BTX yield in coaromatization of n-hexane and methanol over [Zn, Ga]/HZSM-5 catalyst

A series of [Zn,Ga]/HZ catalysts were prepared by impregnation and their catalytic performance in coaroma-tization of n-hexane and methanol, a heat-coupling reaction, were studied in detail. The crystallization, textural properties, morphology, acidity, composition and chemical state were characterized by XRD, N2 adsorption/ desorption isotherms, TEM, py-FTIR, ICP-OES and XPS. The modification of Zn and Ga tunes the acid distri-bution, and more importantly Ga introduction greatly increases the content of active centers Zn(OH)+ from 30 % (1Zn/HZ) to 60 %. As a result, [Zn,Ga]/HZ improves the dehydroaromatization ability and provides higher aromatics yield. The analysis of organic species in catalyst by TG and GC-MS confirms that [Zn,Ga]/HZ produces more aromatics precursors than HZ. Under the conditions of feed ratio (n-hexane/methanol) 3:7, reaction temperature 530 degrees C, and WHSV 1.0 h-1, the BTX yield was significantly increased to 70 %.