Catalytic Transformation of Bio-oil to Benzaldehyde and Benzoic Acid: An Approach for the Production of High-value Aromatic Bio-chemicals

Benzaldehyde and benzoic acid are high-value aromatic chemicals and important intermediates in chemical industry, and the catalytic conversion of biomass-based sources to these aromatic chemicals is of great significance in both academic and industrial fields. This work demonstrated that bio-oil was directionally converted into benzaldehyde and benzoic acid by three-step process under atmospheric pressure and moderate temperatures. The process included the catalytic cracking of biooil into aromatics over 1% Ga/HZSM-5 catalyst, followed by the dealkylation of heavier alkylaromatics to toluene over Re/HY catalyst and the liquid-phase oxidation of toluene-rich aromatics to the targeted chemicals over CoCl2/NHPI (CoCl2/N-Hydroxyphthalimide) catalyst. The production of benzaldehyde and benzoic acid from the bio-oil-derived aromatics, with the overall selectivity of 86.8%, was achieved using CoCl2/NHPI catalyst at 100 °C. Furthermore, adding a small amount of methanol into the feed would efficiently suppress the coke formation, and thus, enhance the yield of aromatics. Potentially, the novel synthesis route offers a green way for the production of higher value-added aromatic chemicals using renewable and environmentally friendly biomass-based sources.