Reductive Amination of Biomass-Derived 2-Hydroxytetrahydropyran into 5-Amino-1-Pentanol Over Hydroxylapatite Nanorod Supported Ni Catalysts

Valuable 5-amino-1-pentanol (5-AP) was efficiently synthesized from biomass-derived dihydropyran over hydroxylapatite nanorod supported Ni catalysts (Ni-HAP), by coupling the in situ generation of 5-hydroxypentanal (5-HP, via the ring-opening tautomerization of 2-hydroxytetrahydropyran (2-HTHP)) and its subsequent reductive amination. The Ni-HAP catalyst with 10 wt% Ni loading exhibited the highest 5-AP yield than the other Ni-HAP catalysts with different Ni loadings and several commercial hydrogenation catalysts, including Ru/C, Pt/C and Pd/C, as well as Raney Ni. High Ni particles dispersion, high reducibility and acidic intensity were found to account for the superior catalytic performance of 10Ni-HAP. The effect of reaction parameters on the catalytic performance was investigated, and an excellent 5-AP yield of 92% was achieved under mild reaction conditions of 80 °C and 2 MPa H 2 . The stability of the Ni-HAP catalyst was studied using a continuous flow reactor, and the sintering of Ni nanoparticles was considered as the major reason for the decline in hydrogenation activity. Graphical Abstract The Ni-HAP catalyst exhibited high catalytic performance to synthesis 5-AP due to the high Ni particles dispersion, reducibility and acidic intensity.