Transfer Hydrogenation of Biomass-Like Phenolic Compounds and 2-PrOH over Ni-Based Catalysts Prepared Using Supercritical Antisolvent Coprecipitation

Transfer hydrogenation (TH) is considered as one of the most promising ways to convert biomass into valuable products. This study aims to demonstrate the performance of high-loaded Ni-based catalysts in the TH of phenolic compounds such as guaiacol and dimethoxybenzenes. The experiments were carried out under supercritical conditions at 250 °C using 2-PrOH as the only hydrogen donor. Ni-SiO2 and NiCu-SiO2 were synthesized using the eco-friendly original method based on supercritical antisolvent coprecipitation. It has been found that guaiacol is rapidly converted into 2-methoxycyclohexanol and cyclohexanol, while the presence of Cu impedes the formation of the latter product. Transformations of dimethoxybenzene position isomers are slower and result in different products. Thus, 1,3-dimethoxybenzene loses oxygen atoms transform into methoxycyclohexane and cyclohexanol, whereas the saturation of the aromatic ring is more typical for other isomers. The Cu addition increases specific catalytic activity in the TH of 1,2-and 1,3-dimethoxybenzene compared to the Cu-free catalyst.