Catalytic hydrogenation of lignin-derived aldehydes over bimetallic PdNi/hydrotalcite catalyst under mild conditions

Abstract

Selective conversion of lignin derivatives into value-added chemicals benefits to develop sustainable chemical engineering and material manufacturing. In this work, a hydrotalcite-supported PdNi bimetallic catalyst was synthesized by introducing Ni to promote Pd dispersion and adjust the charge distribution of the active center, which was used for the catalytic hydrogenation of lignin-derived aldehydes in water under mild conditions. At 30 ℃ and 2 MPa H2, PdNi/HT achieved 99 % of vanillin (VAN) conversion with 100 % selectivity of vanillyl alcohol (VAL), and most of the typical lignin-derived aldehydes could be hydrogenated over this catalyst. This catalyst was steady and could be recycled at least five runs. The introduction of Ni and the nanosheet structure of HT improved the dispersion of the metal particles, significantly reducing the metal particle size. Besides, the Pdδ−–Niδ+ pair and the basic sites of HT facilitated the H2 activation and the adsorption of the aldehyde groups of lignin-derived aldehydes on the catalyst surface, enhancing the hydrogenation efficiency and selectivity.