Catalytic Performance of Bi-functional WC/HZSM-5 Catalysts for n-Hexane Aromatization

Bi-functional tungsten carbide (WC) supported on HZSM-5 (WC/HZSM-5) catalyst samples were prepared and studied in n-hexane aromatization. Two series of catalyst samples with varying WC loadings were synthesized by insitu reduction-carbonization (WC/HZSM-5(RC)) and impregnation methods (WC/HZSM-5(IP)). The catalyst samples were characterized by NH3 temperature-programmed desorption, X-ray diffraction, and scanning electron microscopy combined with energy dispersive spectroscopy. The results showed that WC/HZSM-5(RC) has much higher catalytic activity than WC/HZSM-5(IP). The aromatic selectivity on 5%WC/HZSM-5(RC) was 10.28%, which was much higher than that of HZSM-5 (2.56%). The aromatics (benzene, toluene, and xylene) content in liquid products was 85.07%, much higher than that of HZSM-5 (67.71%). These results are interpreted by the bi-functional mechanism due to the synergistic action between the HZSM-5 and WC.