Constructing highly dispersed Pd on Ca-Al layered double hydroxide for efficiently selective oxidation of cumene

The selective oxidation of cumene to produce cumene hydroperoxide (CHP) with high yield continues to be a challenge when using traditional catalysts, despite the importance of CHP as a key intermediate in phenol industry. Herein, Ca-Al layered double hydroxide (CaAl-LDH) supported Pd was prepared by one-step co-precipitation approach, wherein the Pd species on the CaAl-LDH support were highly dispersed and evidenced by TEM and CO-DRIFTS characterization. The synthetic Pd/CaAl-LDH exhibited the remarkably high catalytic performance, and the selectivity of CHP could reach a very high level (92.1 %) on the high cumene conversion of 52.0 %. The high loading of Pd (4 wt.%) leads to the obvious aggregation of Pd on the edge and surface of CaAl-LDH, Pd nanoparticles could accelerate the decomposition of target product CHP, and thus resulting the decrease of CHP in selectivity. The reaction mechanism was studied by simple radical scavenging experiments, and it was suggested that the activation of oxygen molecules was the main pathway for Pd/CaAl-LDH to promote the oxidation reaction of cumene.