Effect of acidity and porosity of alkali-treated ZSM-5 zeolite on eugenol hydrodeoxygenation

Upgrading of lignin derived bio-oil is a very promising way to relieve humankind's dependence on traditional fossil fuels. Eugenol, a model compound for lignin monomers with a methoxyl group and a hydroxyl group, was hydrodeoxygenated in aqueous phase with Pd/C as hydrogenation catalyst and ZSM-5 zeolite as hydrolysis and dehydration catalysts. The bulky lignin monomers had difficulty in accessing the acid sites of the micropores of ZSM-5 zeolite, thus we introduced mesopores via alkaline treatment under various conditions. Alkali-treated ZSM-5 zeolites showed higher conversion and hydrocarbon selectivity compared to the parent ZSM-5 zeolite. When ZSM-5 zeolite was treated at 338   K, the conversion and the hydrocarbon selectivity increased by 21% and 24%, respectively. In addition, much more weak acid sites of ZSM-5 zeolites after alkaline treatment also promoted the hydrolysis and dehydration process.