The mesopore-elimination treatment and silanol-groups recovery for macroporous silica microspheres and its application as an efficient support for polystyrene hydrogenation

Supported Pd catalyst with an enhanced catalytic performance for polystyrene hydrogenation was successfully prepared by using macroporous silica microspheres (MSM) as the support. In order to eliminate the macromolecular diffusion limitation and improve the metal utilization, MSM was treated with steam at 800 °C first to remove mesopores and then refluxed with aqueous solutions to increase SiOH groups on the surface for Pd immobilization. The optimum support was obtained after the steam treatment for 2 h and using ammonia solution as reflux liquors, and the corresponding catalyst showed superior hydrogenation activity with a high conversion of 95%.