Catalytic conversion of guaiacol in ethanol for bio-oil upgrading to stable oxygenated organics

In this paper, guaiacol was used as a model compound of bio-oil and its catalytic conversion was carried out in ethanol. The effect of supports (SBA-15, ZrO2/SBA-15 and SO42 −/ZrO2/SBA-15) was studied on Pt–Ni based catalysts whereas the effect of active metals was investigated over C-supported Ru, Pt and Pd catalysts. Among the tested catalysts, Ru/C showed the best performance of total guaiacol conversion with high selectivity towards the desired products, cyclohexanol and 2-methoxycyclohexanol (MCH). The reaction pathways of guaiacol in ethanol were clarified based on the product analysis. With the catalysis of Ru/C, the effects of reaction temperature, initial hydrogen pressure, and other typical compounds from bio-oil were investigated. Temperatures had negligible effect on both the conversion of guaiacol and the yields of desired products in the range of 140–260 °C. Guaiacol conversion decreased significantly at initial hydrogen pressures lower than 4.0 MPa. The presence of furfural, acetone, and acetic acid decreased the conversion of guaiacol dramatically while the addition of water had a smaller impact. Further work revealed that the mass and energy efficiency of converting guaiacol into MCH are 100% and 97%, respectively.