Selectivity control of furfuryl alcohol upgrading to 1,5-pentanediol over hydrotalcite-derived Ni-Co-Al catalyst

1,5-pentanediol (1,5-PeD) is a value-added chemical that can be produced from furfuryl alcohol (FFA) via selective scission of CO bond coupled with following hydrogenation reaction. In this work, a series of hydrotalcite-derived Ni-Co-Al catalysts with different Ni/Co ratios were evaluated for FFA upgrading to 1,5-PeD at a temperature range of 413–473 K and hydrogen pressure from 2 to 5 MPa. The catalytic performance and reaction products distribution were found to be highly sensitive to the Ni/Co ratio in the catalysts as well as reaction conditions. The highest catalytic activity was achieved with the Ni-Co-Al catalyst at a Ni/Co atomic ratio of 1:11 (Ni1Co11Al), which attained a 1,5-PeD yield of 42.5 % after 4 h of reaction. The presence of Ni in the Ni1Co11Al catalyst could significantly improve the BET surface area and suppress the growth of metal nanoparticles, leading to its superior catalytic stability in 5 runs. According to the characterization results, it was supposed that hydrogen spillover occurred from the surface of Ni to that of Co species, which was expected to enhance the hydrogen adsorption/activation capability and surface H concentration. The rapid H transfer was beneficial to the hydrogenolysis of furan ring and in situ hydrogenation of reaction intermediates, thus greatly facilitating the activity of the catalyst. Based on the experimental and characterization results, a plausible reaction mechanism was proposed for the selective generation of 1,5-PeD from FFA over the Ni1Co11Al catalyst. The results attained in this paper demonstrated the possibility of using non-precious mixed metal catalyst for FFA upgrading, and could provide useful insights for the design of efficient catalysts.