One pot synthesis of styrene carbonate from carbon dioxide and styrene in water catalyzed by nano-silver modified polyoxometalates

Abstract

Herein is reported an efficient catalytic system for the direct synthesis of styrene carbonate from styrene and CO2. The preparation and characterization of the catalyst using FTIR, TEM, EDX, XPS, and PXRD is presented. The catalyst comprised of nano-silver modified polyoxometalates (Agx/POM) and n-tetra butyl ammonium bromide (TBAB) was employed in the oxidative carboxylation of styrene with CO2 in water as the solvent using H2O2 oxidant. The catalysed reaction was performed in a stainless steel autoclave reactor and the products were analysed using GC-MS and GC-FID. The oxidative carboxylation process was carried out in a one pot set up without need for subsequent work-up and isolation of the styrene oxide formed from the epoxidation process. The process led to 64.6% styrene conversion in 6 h with 96.9% selectivity towards styrene carbonate at 50 ⁰C and 25 bar CO2. The Agx/POM catalyst and TBAB co-catalyst were both beneficial for the reaction and no cyclic carbonate was formed without the catalyst system. When tested on selected styrene derivatives, the catalyst system showed> 90% conversion and> 90% selectivity to the desired cyclic carbonates. The Agx/POM catalyst could be recovered at the end of the reaction and reused with a fresh amount of TBAB without significant loss in activity.

Keywords

• Carbon dioxide
• Nanosilver catalysts
• Oxidative carboxylation
• Polyoxometalates
• Styrene
• Styrene carbonate