Highly active and selective binary catalyst system for the coupling reaction of CO2 and hydrous epoxides

• The coupling reaction had nearly 100% productivity and 100% selectivity.
• The effect of water on the coupling reaction of CO2-epoxide could be minimized.
• Zn–CoIII DMCC was suitable to various epoxides and required no solvent.

Although most of the zinc-containing catalysts show excellent catalytic activity for the coupling reaction of carbon dioxide (CO2) with epoxides, generally, trace amounts of water in the reaction systems could cause a significant decrease of the catalytic activity. In this work, a nanoporous zinc-cobalt double metal cyanide complex (Zn–CoIII DMCC) with high surface area was synthesized via a modified hydrothermal process using tri-block copolymer EO20PO70EO20 (P123) as the template. When cetyltrimethylammonium bromide (CTAB) was used as the co-catalyst, the Zn–CoIII DMCC/CTAB binary catalyst system could effectively catalyze the coupling reaction of CO2 with hydrous propylene oxide (PO), producing propylene carbonate (PC) with nearly 100% productivity and 100% selectivity. This binary catalyst system could also catalyze the coupling reaction of other commercial epoxides and CO2 without using any solvents with nearly 100% productivity and 100% selectivity. With such new catalyst system, hundreds of ppm water in the reaction system will no longer be the matter.

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