Porous polymer beads with grafted poly(tertiary amine) as catalysts for fixation of carbon dioxide into propylene carbonate

Porous polymer beads with grafted poly(tertiary amine) were prepared by grafting triethylenetetramine to porous crosslinked poly(methyl acrylate) beads via ester amidation reaction, followed by Eschweiler–Clarke methylation reaction using formaldehyde and formic acid to converting the primary and secondary amine groups to tertiary amines in the beads. The tertiary amine groups in the beads were protonated with hydrochloric acid, hydrobromic acid or hydriodic acid, and the protonated tertiary amine group-containing beads showed high catalytic activity and high selectivity for the formation of propylene carbonate through cycloaddition of propylene oxide with CO₂, while free tertiary amine group-containing beads exhibited almost no catalytic activity. The recyclability of the catalyst was studied, and slight loss of the activity was observed after five runs.