A review on sources and extraction of phenolic compounds as precursors for bio-based phenolic resins

Residues from biomass processing/harvesting (e.g., straw, saw chips, bark) contain value-added chemicals for multiple applications. Biomass residues can be converted to chemicals and fuels, unlike other renewable sources such as wind and hydro, with the added benefit of reducing economic and environmental costs associated with residue disposal. Pyrolysis, the thermal degradation of the biomass, can convert these low-value residues to high-value energy or chemicals. The pyrolysis oils derived from lignocellulosic biomass are of particular interest as potential sources of bio-phenols. This review is focused on the extraction and recovery of phenolic compounds from bio-oil produced during the pyrolysis of various biomass residues with a particular focus on the potential of hemp residues (hurds and straw) as a source of phenolic compounds. Considerable progress has been made toward producing cost-effective renewable phenolic resins. New and advance technologies and materials are being used for the production of bio-based resins. However, further investigation is required on the optimization of pre-treatment, extraction, and analytical techniques to meet the challenges of satisfactory quality and low cost of renewable resins.