Highly Effective Rh/NaNbO3 Catalyst for the Selective Hydrogenation of Benzoic Acid to Cyclohexane Carboxylic Acid Under Mild Conditions

Rh/NaNbO3 catalyst was prepared by a facile solvothermal method combined with photo-deposition technique. Over this catalyst, both conversion and selectivity were up to 100.0% in ten reaction recycles for the selective hydrogenation of benzoic acid to cyclohexane carboxylic acid at room temperature and 0.5 MPa H2 pressure. TOF value of the catalyst was 207 h−1 for this hydrogenation reaction. The excellent performance and the mild hydrogenation conditions were among the best of the reference catalysts with different supports or surface metal active component. Multiple characterization techniques were adopted to further study the essence of the superior hydrogenation performance. It was found that the abundant oxygen vacancies and the reduction in situ of Rh species accounted for the excellent hydrogenation performance. Besides, the reducible perovskite support, small Rh species particle, specific morphology and pore structure of the catalyst also played important roles in improving the hydrogenation reaction. After eleven hydrogenation recycles, the inactivation of the catalyst was also investigated, and attributed to the carbon deposition and the leaching of Rh species during hydrogenation process. It is an attractive work to design the highly efficient catalysts for benzoic acid hydrogenation with potential application value.