Aromatization of glycerol/alcohol mixtures over zeolite H-ZSM-5

Abstract

The aromatization of glycerol is conducted over zeolite H-ZSM-5 for glycerol valorization. Due to its high viscosity, glycerol is diluted with water, methanol, ethanol, isopropanol or isobutanol. With the aqueous glycerol feed, the total aromatics yield is low and catalyst deactivation is fast. The mixture of glycerol with each alcohol is thus used as a feed, resulting in higher aromatics yields. Furthermore, the carbon fraction of aromatic products depends upon the alcohol mixed with glycerol. In case of the glycerol/methanol feed, the formation of trimethylbenzenes along with xylenes is pronounced, since both reactant constituents can be transformed into heavy C-9 aromatics and then dealkylated to xylenes (major) and toluene (minor). In contrast, the use of higher alcohols for glycerol dilution leads to the preferential production of ethylbenzene and ethylmethylbenzenes, though xylenes and trimethylbenzenes are produced, due to alkylation of ethylene formed via dehydration (ethanol) or dehydration/cracking (isopropanol and isobutanol).