双中心多孔聚合物作为多相催化剂实现CO2在温和条件下高效转化

由于对化石燃料的高度依赖和二氧化碳(CO2)的过度排放,大气中CO2浓度从280 ppm上升到400 ppm左右,导致全球变暖和其他气候问题.在这种情况下,如何有效降低空气中的CO2浓度成为近年来最迫切的研究领域之一.另一方面,作为一种无毒、廉价且丰富的C1资源,CO2也可以转化为各种高附加值的工业产品,如甲酸、一氧化...

Combination of binary active sites into heterogeneous porous polymer catalysts for efficient transformation of CO2 under mild conditions

The transformation of CO2 into cyclic carbonates via atom-economical cycloadditions with epoxides has recently attracted tremendous attention. On one hand, though many heterogeneous catalysts have been developed for this reaction, they typically suffer from disadvantages such as the need for severe reaction conditions, catalyst loss, and large amounts of soluble co-catalysts. On the other hand, the development of heterogeneous catalysts featuring multiple and cooperative active sites, remains challenging and desirable. In this study, we prepared a series of porous organic catalysts (POP-PBnCl-TPPMg-x) via the copolymerization metal-porphyrin compounds and phosphonium salt monomers in various ratios. The resulting materials contain both Lewis-acidic and Lewis-basic active sites. The molecular-level combination of these sites in the same polymer allows these active sites to work synergistically, giving rise to excellent performance in the cycloaddition reaction of CO2 with epoxides, under mild conditions (40 ℃ and 1 atm CO2) in the absence of soluble co-catalysts. POP-PBnCl-TPPMg-12 can also efficiently fixate CO2 under low-CO2-concentration (15％ v/v N2) conditions representative of typical CO2 compositions in industrial exhaust gases. More importantly, this catalyst shows excellent recyclability and can easily be separated and reused at least five times while maintaining its activity. In view of their heterogeneous nature and excellent catalytic performance, the obtained catalysts are promising candidates for the transformation of industrially generated CO2 into high value-added chemicals.