Organic Acid-Assisted Preparation of Hydroxyapatite-Supported Ni Catalysts for Arene Hydrogenation

Graphical Exploring the impact of structural variations in organic acids on catalyst properties unveils crucial insights for enhancing arene hydrogenative activity. The Ni catalyst, supported by hydroxyapatite and aided by a hydroxy-dicarboxylic acid (tartaric acid) with an optimal ratio, resulted in relatively smaller Ni nanoparticles, a higher Ni 0 proportion, and increased acidic sites, showcasing exceptional hydrogenation performance. Developing non-noble metal catalysts that can efficiently and selectively hydrogenate arenes remains a significant challenge. In this study, we developed efficient 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 good substrate compatibility. The influence of carbon chain lengths and side-chain hydroxyl or amino groups on dicarboxylic acids used in the catalyst preparation was comprehensively investigated. Characterizations and kinetic studies demonstrated the influence of organic acids on the size of Ni nanoparticles, the proportion of metallic nickel, and the strength of surface acidity. These factors influenced the activation of arene and hydrogen, thereby affecting the hydrogenative activity. Notably, hydroxyapatite-supported Ni catalyst, assisted by tartaric acid (Ni-TA/HAP) with an appropriate tartaric acid-to-nickel ratio, resulted in relatively smaller Ni nanoparticles, an increased proportion of Ni 0 , and more acidic sites, thereby exhibiting the best hydrogenation performance.