Preparation And Catalytic Performance Of Silver Nanoparticle Catalysts Supported On Layered Double Hydroxides

Olefin epoxidation, especially in the case of styrene, has attracted increasing interest in the fields of science and industrial application. Recently rapidly revolved green chemistry makes it necessary to develop a highly efficient and fairly facile oxidant method for the epoxidation of styrene. Supported silver catalysts have been widely investigated because of the high catalytic performance of olefin epoxidation.Layered double hydroxides (LDHs), also known as hydrotalcite-like materials, are a class of promising catalysts and supports. LDH structure is based on brucite (Mg(OH)2)-like layers in which some of the divalent cations have been replaced by trivalent cations giving positively-charged sheets, endowing LDHs with ordered array of hydroxyl sites on surface which is able to favor Olefin epoxidation. In this present study, Ag/LDHs catalysts was prepared using a facile chemical reduction method, and then investigated for the activity and selectivity of the prepared catalysts in the liquid-phase epoxidation of styrene. The main results obtained are as follows:1. Using a chemical reduction method, we prepared Ag/LDH with different loading with Ag highly dispersed on the support. By changing the preparation method, we prepared Ag/LDH catalyst via roast reduction process. Evaluation of epoxidation of styrene shows that the Ag nanoparticles in our case exhibited a highly enhanced performance in comparison with that prepared via a conventional roast reduction process.2. By varying reaction time and reaction temperature of Ag/LDHs catalysts in the liquid-phase epoxidation of styrene by TBHP, the conversions of styrene were tuned. A proper catalytic condition with the optimum conversion of styrene and the selectivity of styrene oxide was optimized to be a reaction time of 8h and a reaction temperature 82℃.