Selective catalytic conversion of bio-oil over high-silica zeolites

• Selective catalytic conversion of bio-oil over high-silica zeolite were investigated.
• All these zeolites had high deoxygenation ability for the bio-oil.
• The oxygen in the bio-oil was removed mainly in the form of H2O.
• Beta-type zeolite of HSZ-960 showed high selectivity to hydrocarbons.
• Acid sites in zeolite had great effect on the catalytic activity for deoxygenation.

Four high silica zeolites, i.e., HSZ-385, 890, 960, and 990 were utilized for the selective catalytic conversion of bio-oil from Fallopia japonica to certain chemicals in a fixed-bed reactor. The Beta-type HSZ-960 zeolite showed the highest selectivity to hydrocarbons, especially to aromatics as well as PAH compounds with the lowest unwanted chemicals while HSZ-890 showed high selectivity to aromatics. NH3-Temperature Programmed Desorption (TPD) analysis indicated that different amounts of acid sites in different zeolites determined the catalytic activity for the oxygen removal from bio-oil, in which the acid sites at low temperature (LT) region gave more contribution within the utilized temperature region. The reusability test of HSZ-960 showed the stability of hydrocarbons yield at higher temperature due to the significant contribution of coke gasification which assisted further deoxygenation of bio-oil. These results provide a guidance to select suitable zeolite catalysts for the upgrading of bio-oil in a practical process.

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