Analysis of property variation and stability on the aging of bio-oil from fractional condensation

A series of experiments on bio-oil storage and property measurement were conducted to compare the stability of multi-stage bio-oil from fractional condensation at normal pressure and temperature. The samples from bio-oil stored for 0, 5, 15, 35, 75 days were analyzed for chemical components, moisture, pH and thermophysical properties. During storage, moisture, thermal conductivity, specific heat capacity and viscosity exhibited upward tendencies whereas pH and higher heating value decreased gradually. The properties varied more frequently in the early period of storage due to active components in fresh bio-oil. The relative contents of aliphatic compounds with small molecular weights were significantly reduced after storage but those of phenols were improved slightly. The bio-oil from high condensing temperature showed fewer changes of properties and components during long-term storage. Bio-oil aging was mainly consequent on the reaction of polymerization and oxidation, and results indicated that the bio-oil obtained from 90 degrees C condensing temperature was more appropriate for combustion and processing because of ample high value-added components and stable properties. (C) 2019 Elsevier Ltd. All rights reserved.