Enhanced yield of benzene, toulene, and xylene from the co-aromatization of methane and propane over gallium supported on mesoporous ZSM-5 and ZSM-11

In this work, mesopore was introduced to ZSM-5 and ZSM-11 to increase the yield of benzene, toluene, and xylene (BTX) from the co-aromatization of methane and propane. Co-aromatization of methane and propane (10:1 M ratio) at 550 °C revealed that gallium oxide (2 wt%) supported on mesoporous zeolites showed higher BTX selectivity and BTX yield than that on microporous zeolites. In particular, the BTX yield of GaOy/meso-HZSM-11 (13.94%) was higher than that of GaOy/meso-HZSM-5 (11.20%), in addition to showing more stable activity up to 6 h. H2-TPR analysis indicated that GaOy/meso-HZSM-11 contains more mobile Ga2O species and GaO+ ion than GaOy/meso-HZSM-5. In addition, NH3-TPD analysis confirmed that such highly dispersed Ga species interact with Brönsted-Lowry acid sites of zeolites to produce medium acid site acting as Lewis acid more abundantly in the former than the latter. In summary, the superior co-aromatization performance with the highest reactant conversion of GaOy/meso-HZSM-11 was achieved by the synergetic effect of Lewis acid site formed by dispersed Ga species and Brönsted-Lowry acid sites of mesoporous HZSM-11.