Design of a difunctional Zn-Ti LDHs supported PdAu catalyst for selective hydrogenation of phenylacetylene

摘要

To suppress hydrogenation of alkene at complete alkyne conversion, a difunctional Zn-Ti layered double hydroxides (LDHs) supported bimetallic PdAu alloy catalyst with alkalinity was designed and prepared by a photochemical reduction method. On the basic of TEM and XPS results, the formation of Pd-Au alloy was determined. The alloy nanoparticles had incorporated into the inter-layer region of LDHs, giving a strong interaction between them. As expected, the PdAu/ZnTi catalysts exhibited excellent styrene selectivity (over 90%) even when the reaction time was prolonged (6 h) after full conversion of phenylacetylene. Such excellent selectivity is attributed to the synergistic effect between bimetallic alloy nanoparticles and Zn-Ti LDHs. The selective formation of polar hydrogen species derived from the heterolytic dissociation of H-2 at the interface between PdAu alloy and basic sites of Zn-Ti LDHs is more favorably reactive to alkyne compared with alkene. Moreover, the Zn-Ti LDHs supported PdAu catalyst exhibited great recyclability. The difunctional catalyst is expected to be potentially promising for industrial applications.