Synthesis of ordered mesoporous Pd/carbon catalyst with bimodal pores and its application in water-mediated Ullmann coupling reaction of chlorobenzene

Heterogeneous palladium catalysts have been supported on the ordered mesoporous carbons (Pd/OMC) with bimodal pores which are prepared by the surfactant-templating approach. Characterization using XRD, TEM, XPS, H₂ chemisorption, and N₂ sorption techniques reveals that the Pd/OMC catalysts have the ordered 2-D hexagonal mesostructure (space group of p6mm), extremely high surface areas (~1800 m²/g), large pore volumes (~1.64 cm³/g), bimodal pores (6.3 nm of primary mesopores and 1.7 nm of secondary mesopores inside the pore walls), hydrophobic carbon surface, and small metal particles well-dispersed inside the secondary small mesopores. This catalyst exhibits a high yield of 43% for biphenyl from the Ullmann coupling reaction of chlorobenzene in water at 100 °C without assistance of any phase transfer catalyst and can be reused up to 10 times, providing potential opportunities for industrial applications such as coupling and hydrogenation reactions.