(624g) Convert Ethane to Aromatics By Ptmn/SiO2 and H-ZSM-5 Bifunctional Catalyst

The shale gas revolution in the US has led to a significant increase in light hydrocarbon production, due to the new technology of horizontal drilling and fracking. Ethane dehydroaromatization (EDA) is an attractive reaction process to convert ethane to valuable aromatics such as benzene, toluene, and xylene (BTX). The commonly used catalysts for propane dehydroaromatization (PDA) are metal-promoted HZSM-5 catalysts, such as Ga/HZSM-5 and Zn/HZSM-5, which suffer from low activity and poor stability for EDA due to the requirement for higher reaction temperature. A PtMn/SiO₂ + HZSM-5 is used as the bifunctional catalyst to investigate the effect of metal-to-acid site ratio, hydrogen co-fed, and reaction conditions on the product distributions for EDA. The catalyst with PtMn/SiO₂ + HZSM-5 = 1/3 ratio could reach 82%-90% final product BTX selectivity with conversion ranging from 15%-30%, while PtMn/SiO₂ + HZSM-5 with 1/1 ratio showed the highest ethane conversion rate. Low volume percentage hydrogen co-feeding did not have a significant effect on the product selectivity and conversion, while slightly improving the catalyst deactivation. However, a larger amount of co-feeding resulted in increased methane selectivity and a decreased BTX selectivity. The excess presence of hydrogen saturated the olefin intermediates to form alkane, which produced methane by monomolecular cracking on HZSM-5. Increasing reaction temperature from 550 ºC to 650 ºC, the benzene percentage is increased, while 600 ºC showed the highest final BTX selectivity.