Spatial structure modulation of Poly(ionic liquid)s with hierarchical porous structure for efficiently catalytic conversion of CO2 into cyclic carbonates

Abstract

Among the many resource utilization routes of CO2, the reaction of CO2 with epoxides to synthesis cyclic carbonates is a well-established method, which is not only environmentally friendly but also in line with atomic economy for heterogeneous catalysts. Aimed at insufficient exposure of active sites and poor catalytic activity, a series of P[VImX][Br] Poly(ionic liquid)s (PILs) catalysts was developed with different porous structure. PILs catalysts with hierarchical porous structure and particle size were obtained by adjusting the ratio of ILs and DVB monomer. When the ratio of ILs increased, the specific surface area and the degree of dispersion of the particles firstly increased and then decreased, and the larger specific surface area and the degree of dispersion were more favorable for the full exposure of the active sites, which in turn improved the catalytic activity. Among them, the optimal ratio of ILs is 0.4 (P[VIm0.4][Br]), which has relatively large specific surface area and high degree of dispersion, and the highest catalytic activity, and the conversion rate of propylene oxide (PO) reaches 95 %. In addition, the catalyst exhibited good recoverability after five cycles and obtained a wide substrate applicability. This paper provides a new idea for tuning the structure of PILs for high efficient catalysis.