Catalytic activity of ZIF-8 in the synthesis of styrene carbonate from CO2 and styrene oxide

The catalytic activity of ZIF-8 in the synthesis of styrene carbonate from carbon dioxide and styrene oxide is presented. ZIF-8 crystals displayed catalytic activity even at temperatures as low as 50 °C, with styrene carbonate yields as high as ~ 54% at 100 °C. In contrast to many prior-art catalysts, solvents or co-catalysts were not required. Pyridine and ammonia were used as probe molecules to estimate the type and density of acid sites in fresh and reused ZIF-8 catalysts. DRIFT spectroscopy of adsorbed pyridine revealed the presence of both Brönsted (B) and Lewis (L) acid sites. The B-sites have nearly vanished in the case of recycled ZIF-8 catalysts. The simultaneous presence of both the acid sites and the nitrogen basic moieties from the imidazole linker in ZIF-8 promoted the adsorption of the CO2 on the solid surface and its further conversion to the cyclic carbonate. The ZIF-8 catalysts could be recycled and reused without significant loss in catalytic activity.

Graphical abstractThe catalytic activity of ZIF-8 crystals in the synthesis of styrene carbonate from carbon dioxide and styrene oxide is demonstrated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► ZIF-8 crystals were active catalysts in the synthesis of styrene carbonate from carbon dioxide and styrene oxide. ► Zn acid sites and nitrogen basic moieties from the imidazole in ZIF-8 promoted the conversion to the cyclic carbonate. ► The ZIF-8 catalysts could be recycled and reused without any significant loss in catalytic activity.