Ni–Al2O3/CN Nanocatalysts for Selective Hydrogenation of Furfural

Cheap Ni catalysts are highly active for the catalytic conversion of biomass, but it is challenging to prepare Ni-based catalysts with high selectivity and stability under mild conditions. Adjusting the adsorption strength of Ni catalysts to reaction substrates and intermediates by metal introduction is an effective strategy to achieve high yields of products. In this paper, a series of xNi-Al2O3/CN catalysts were prepared by introducing Al content as a variable and were used for hydrogenation of furfural (FAL) to tetrahydrofurfuryl alcohol (THFOL). Under the mild condition of 90 °C, the yield of the 3Ni–Al2O3/CN catalyst with the optimal Ni/Al ratio of 3:1 reached 99.9%, which was 8.3 times that of Ni/CN without Al. The improvement in the catalytic performance was mainly attributed to the enhanced interaction of Ni and Al2O3 by Al introduction, which increased the content of active Ni0 and Lewis acid. This not only promoted the adsorption and activation of H2 and FAL but also increased the adsorption strength of 3Ni–Al2O3/CN on the intermediate FOL to improve THFOL selectivity. The correlation between the modulation of Al content and catalytic performance was explored in detail through relevant characterization and theoretical calculations. In addition, Al-introduced 3Ni–Al2O3/CN maintained high stability over 10 cycles relative to the rapid deactivation of Ni/CN, which was attributed to the strong interaction of Ni–Al2O3. This strategy to modulate the activation ability of the catalyst provides a reference for the logical design of efficient bifunctional metal catalysts.