Highly Efficient Catalyst Derived from Ultrathin Co-Based Layered Double Hydroxide for Catalytic Transfer Hydrogenation of Guaiacol under Mild Conditions

Exploiting efficient catalysts to promote the sustainable production of chemicals from biomass remains an important challenge. Here, a series of ultrathin NixCoyAlz (∼1–3 nm) layered double hydroxides (LDHs) were successfully prepared to fabricate highly active catalysts for catalytic transfer hydrogenation (CTH) of guaiacol. Among the prepared catalysts, the Ni0.1Co3.9Al1 catalyst exhibits the best catalytic performance with ∼100% guaiacol conversion and 94% cyclohexanol selectivity under 180 °C and 0 MPa N2. Moreover, the reaction rate of 63.60 × 10–5 mol·gcat–1·min–1 is superior to the reported catalysts under comparable reaction condition. In addition, the Ni0.1Co3.9Al1 catalyst reduced at 600 °C exhibits excellent performance, achieving 99.9% guaiacol conversion and 92.5% selectivity for cyclohexanol under 160 °C and 0 MPa of N2. This reaction temperature is significantly lower than those reported for comparable systems. This excellent activity is mainly due to the small metal particle size and highly dispersed metal particles induced by the ultrathin LDHs, and the synergy between Ni and Co sites in the Ni–Co alloy. Due to the high oxygen affinity of the Co catalyst, it favors the cleavage of the Caryl–OCH3 bond, while the Ni catalyst enhances the aromatic ring hydrogenation. The addition of Ni to the Co catalyst enables the formation of the Ni–Co alloy, which promotes the cleavage of the Caryl–OCH3 bond and intermediate phenol hydrogenation, thus leading to an excellent performance of guaiacol CTH. Moreover, the Ni0.1Co3.9Al1 catalyst displays good stability with negligible activity loss over six runs. This work provides an efficient route for synthesizing highly active catalysts and fundamental insights into the CTH of guaiacol.