Better Performance in C2-Conversion to Aromatics by Optimized Feed and Catalysts

Abstract

We identify favorable parameters for the formation of aromatics from ethanol-based feeds over ZSM-5. An ethanol partial pressure of 0.3 bar, a reaction temperature of ∼700 K, a low weight hourly space velocity (WHSV), and a high Brønsted acid site density increase the content of aromatics, in the latter case, on the expense of lifetime. The aromatic fraction composition changes with the WHSV and nSi/nAl ratio. Water cofeed increases the content of aromatics in the C2:H2O stoichiometry of 1:0.5 (equals diethyl ether as feed) but decreases it if this is exceeded. Diethyl ether and ethylene lead to more aromatics than ethanol feed. The lifetime until deactivation increases in the order ethanol < diethyl ether < ethylene. This points at different reaction and/or deactivation mechanisms in converting the three feeds. Thus, a water-poor feed effectively improves the catalyst lifetime and productivity in the ethanol conversion to aromatics.