Ni-bearing nanoporous alumina loaded ultralow-concentrated Pd as robust dual catalyst toward hydrogenation and oxidation reactions

Abstract

Rational combination of noble and non-noble active metals in heterogeneous catalysis especially emerged as a dual catalyst is intriguing on account of their certain promotive catalytic activity. Herein, we report Ni-Pd co-supported nanoporous alumina with ultralow-loading Pd and concentration-adjusted Ni as dual catalyst both affording robust hydrogenated and oxidized capacity. The active Pd species in the alumina emerged as the quasi single site state responsible for hydrogenation of phenylacetylene thanks to the introduction of Ni compared with the only Pd-bearing ones, while the Pd and Ni both acted as the catalytically active center specific to the oxidized activity of benzyl alcohol. Ulteriorly, it is demonstrated that the chemical state of quasi single site Pd species in alumina was obviously influenced in the presence/absence of nickel compared to aggregated Pd. The catalytic results further affirmed that the introduced nickel in the alumina is beneficial to the improvement of catalytic hydrogenated property, and the selectivity of products in the phenylacetylene hydrogenation was obviously tuned based on the varying concentrations of nickel-containing catalyst in the presence of low additive dosage of catalyst. Impressively, as the dual catalyst, the resulted catalyst also revealed the superior catalytic oxidative capacity(99% conversion, 97% selectivity) toward the oxidation of benzyl alcohol with molecular oxygen resulted from the synergetic effect of active Pd and Ni species.