The Influence of Steam on the Zeolite Catalytic Upgrading of Biomass Pyrolysis Oils

Abstract

Zeolite catalytic cracking upgrading of highly oxygenated biomass pyrolysis liquids has been proposed as a means of producing hydrocarbon oils ans gases. During catalysis the oxygen from the pyrolysis liquids is removed as water, carbon monoxide and carbon dioxide. Biomass derived pyrolysis oils have a relatively low hydrogen content wich limits the potential yield of hydrocarbon produtc particularly when hydrogen is used in the removal of oxygen through the formation of water. The addition of steam to the pyrolytic vapours prior to upgrading may provide a potencial source of hydrogen during cataysis to increase hydrocarbon formation. I this work steam was added to the vapours produced from the pyrolysis of biomass. The steam/[yrolytic vapous mixture was oasses over a static bed of zeolite catalyst, HZSM-5. The presence of steam led to the formation of large amounts of gaseous products with a yield in excess of 70% at 550 [deg] C catalyst temperature. The catalytic oil yield was reduced as the catalysis temperature was increased from 400 to 550 [deg] C.