Efficient conversion of methane to aromatics in the presence of methanol at low temperature

Abstract

The efficient utilization of methane has long been extremely challenging, especially at relatively mild conditions. We present a novel approach to convert methane to benzene, toluene, and xylene (BTX) efficiently on Zn/ZSM-5 catalyst in the presence of methanol at relatively mild reaction conditions (the range of temperature is 400–500 °C and molar ratio nCH3OH/nCH4 of 0.4–1.2), which is in the preferred reaction condition for the methanol to aromatics process (MTA). The methane conversion reaches 14.8% and the BTX selectivity is increased by 9.3% using the co-reaction of methane with methanol, which is systematically studied using AAS, XRD, NH3-TPD, and N2 adsorption and desorption. Our results show that the presence of strong acid sites, loaded Zn metals, and methanol in the feedstock are indispensable conditions for methane transformation at low temperature. The incorporation of methane carbon into the aromatics is directly evidenced by the 13C NMR spectroscopy. In addition, the kinetic experiments show that the presence of methanol significantly reduces the activation barrier for methane conversion. Therefore, our approach to efficiently convert CH4 into aromatics at low temperature and improve BTX selectivity in MTA reactions potentially facilitates the industrialization of MTA.