Improvement and Modification of Heavy Bio-oil by Reduced Iron Oxide

The heavy bio-oil obtained by biomass pyrolysis was taken as the research object, and iron oxide was loaded to silica fiber to prepare composite iron based oxygen carrier to deoxidize and modify the heavy bio-oil at its reduced state under the reaction conditions of 350 ℃ and 1.48 MPa. By comparing the changes in the composition and structure of the heavy bio-oil and oxygen carrier before and after partial deoxidation, it was found that the oxygen element in the heavy bio-oil was partially transferred to the oxygen carrier, the mass fraction of oxygen element in the oil decreased from 29.83% to 26.12%, and the reduced oxygen carrier (Fe3O4/FeO) was oxidized to Fe3O4; the effective hydrogen/carbon molar ratio of the heavy bio-oil obtained by calculation increased from 0.67 to 0.80 by nearly 18.44%, and its calorific value increased to 27.6 MJ/kg; most of the complex organic components in the composition were condensed into carboxylic acids and phenols, ketones and aldehydes decreased obviously, while hydrocarbons increased significantly; ethanol was later added for catalytic esterification, as a result of which lipids and phenols became the main components in the heavy bio-oil, and the oil quality was obviously improved. In addition, the oxygen carrier compound with silica fiber has stable structure after reduction and can be used for multi-cycle partial deoxidation of the oil. © 2022 Science Press. All rights reserved.