Review on Aging of Bio-Oil from Biomass Pyrolysis and Strategy to Slowing Aging

Bio-oil from biomass pyrolysis is a promising alternative and clean source of biofuels, chemicals, and materials. Its chemical composition, physical and chemical properties, and multiphase behavior change over time, because of aging, which significantly affects its storage, handling, transportation, upgrading, and application. This Review focuses on studying bio-oil aging, and its outlook, primarily covering the following four components: (1) the chemical composition, physical and chemical properties, and multiphase behavior of bio-oil; (2) the indicators for measuring the degree of aging and aging characteristics, including physical and chemical properties change during long-term and accelerated aging of bio-oil; (3) the aging mechanisms and kinetics emphasizing the reactions during the aging process and different kinetic models based on different aging indicators; (4) the potential approaches to slowing bio-oil aging. This Review presents highlights in developing aging mechanisms and kinetics that will allow the reader to have an in-depth understanding of the effect of aging on bio-oil properties and the approaches to improve the resistance of bio-oil aging.