Alkali-Boosted Catalytic Activity of Co-Based Catalysts Supported by Nanoporous Carbon in the Hydrodeoxygenation of Guaiacol

The catalytic activity and selectivity of Co-based catalysts supported on home-made nanoporous carbon was studied as a function of the type of alkali promoter (Ca and Mg). The catalysts were characterized by N2 adsorption/desorption isotherms, temperature-programmed reduction, CO chemisorption, and X-ray diffraction patterns. The catalysts were compared against carbon-supported alkali-promoted Ni-based catalysts and Re-containing catalysts. The catalytic activity of the Co-based catalyst was clearly enhanced in the presence of Ca and Mg, and it was higher than the Ni-based catalysts and comparable to that obtained using an ReC catalyst. The initial activity of the Mg-promoted catalyst increased by a factor of up to 2.5 times higher compared to the non-promoted catalyst. Moreover, this catalyst showed a turnover frequency of up to 5 times higher than equivalent carbon-supported Re-based catalysts. Significant changes were not observed in the selectivity of products after the incorporation of alkali, with cyclohexane being the main product. However, it was demonstrated that the presence of alkali led to a faster and higher production of cyclohexane from the demethoxylation of phenol and the dehydrogenation of cyclohexanol. The present results suggest that Co-based catalysts are an economical alternative for the catalytic conversion of representative target molecules from bio-oil feed.