Pd/BN catalysts for highly efficient hydrogenation of maleic anhydride to succinic anhydride

A 0.33 wt% Pd/BN catalyst has been proved highly active for the liquid-phase selective hydrogenation of maleic anhydride (MA) to succinic anhydride (SA) at room temperature and highly selective to SA within a wide temperature range, far beyond the Pd/Al2O3 and Pd/MgO catalysts. An SA productivity of 6000 KgSA KgPd−1 h−1 and a high TOF value of 9.0 s−1 can be achieved at room temperature on the Pd/BN, and the high SA selectivity over 99.7% can be retained at the reaction temperature up to 150 ºC. Detailed structural characterizations and reactant-adsorption/desorption tests have demonstrated that the support effect on MA hydrogenation is related not only to the adsorption configurations of MA on Pd, which exhibits the indirect effect of the support via the electronic interaction with Pd, but also to the direct adsorption of MA on the support itself. In particular, for our catalysts with the low Pd loading, the difference of metal centers is largely masked by the adsorption of the support itself. For the Pd/BN, the predominant MA adsorption on Pd through a di-σ mode, the weak MA adsorption with a small amount on BN, and a high H-spillover ability are responsible for its high activity and selectivity. Moreover, it has been also revealed that the catalyst prereduction temperature can change the catalytic performance of the Pd/BN through an integrated effect including the removal of residual chlorine on Pd and the growth of Pd particles.