(236e) Hydrotreating of Catalytic Pyrolysis Oils
Hydrocarbon fuels can be prepared from biomass via catalytic fast pyrolysis followed by hydrotreating. The aim of this work was to evaluate how the properties of the catalytic pyrolysis oils impact the hydrotreating requirements. Five catalytic fast pyrolysis oils, all prepared from pine over ZSM-5 based catalysts, were hydrotreated over sulfided CoMo catalyst at the same conditions. The catalytic pyrolysis oils had been prepared in two different reactor systems, a bubbling fluidized bed upgrader or a Davison Circulating Reactor connected to a biomass pyrolyzer. The catalytic pyrolysis oil oxygen contents on dry basis varied from 12% to 20%. The product oxygen content, hydrogen consumption, and carbon efficiency for hydrotreating could be well correlated by the catalytic pyrolysis oil oxygen content. The correlations were valid for the oils prepared in different reactors, over different ZSM-5-based catalysts, and upgraded at different temperatures. The impact of hydrotreating conditions - pressure, temperature, and catalyst loading - were further tested for one catalytic pyrolysis oil. Deoxygenation of CFP oils to <1wt% oxygen can be achieved by different operating combinations. However, the conditions impact the degree of aromatic compound saturation and hence the oil H:C ratio and hydrogen consumption.