Remarkably Efficient Hydroxyapatite-Supported Ni Catalysts for Arene Hydrogenation: Effect of Organic Acid Additives

Developing non-noble metal catalysts that can efficiently and selectively hydrogenate arenes remains a significant challenge. In this study, we developed highly efficient and sustainable hydroxyapatite-supported Ni catalysts for the arene hydrogenation based on an organic acid-regulated impregnation strategy. These easily accessible Ni catalysts demonstrated exceptional efficiency, selectivity, reusability, and also good substrate and functional group compatibility. The influence of carbon chain lengths and side-chain hydroxyl or amino groups on low-cost dicarboxylic acids used in the catalyst preparation was comprehensively investigated. Characterizations and kinetic studies demonstrated the influence of organic acid additives on the size of Ni nanoparticles, the proportion of metallic nickel (Ni0), and the strength of surface acidity. These factors influenced the absorption and activation of arene and hydrogen, thereby affecting the hydrogenative activity. Notably, hydroxyapatite-supported nickel catalyst, assisted by tartaric acid (donated as Ni-TA/HAP) with an appropriate tartaric acid-to-nickel ratio, resulted in relatively smaller Ni nanoparticles, an increased proportion of Ni0, and more acidic sites, thereby exhibiting the best hydrogenation performance. This organic acid-assisted strategy offers a potential alternative for preparing sustainable Ni-based catalysts for efficient hydrogenation processes.