Integrated Pyrolysis and Biorefinery Strategies for Valorising Forestry Biomass through the Production of Calcium Acetate

Forest biomass represents a promising resource within the bioeconomy, with significant potential for conversion into high-value chemicals and bioproducts. This work proposes an innovative thermochemical biorefinery pathway to valorise two types of underutilised forest biomass: Aleppo pine (Pinus halepensis) and Holm oak (Quercus ilex), transforming it into value-added bioproducts that can provide economic incentive for sustainable forest management. A targeted biorefining methodology was developed, incorporating vacuum distillation, phenolic adsorption resin, and neutralisation with calcium oxide, to selectively isolate and purify acetic acid—the predominant component of bio-oil—in the form of calcium acetate (CaAc2). Holm oak consistently produced higher yields from the aqueous phase bio-oil compared to Aleppo pine, underscoring its superior suitability for this valorisation pathway. This methodology demonstrated high efficiency in recovering calcium acetate from bio-oil, yielding 111.1 g CaAc2/kg of bio-oil for Holm oak, with a 70.5 wt.% acid recovery, and a 99.6 wt.% phenolic removal. Overall, this work significantly advances pyrolysis oil biorefining by introducing a novel and effective approach for acetic acid extraction via calcium acetate production, a valuable industrial chemical.