Bifunctionalized polyacrylonitrile fibers as highly efficient and selective heterogeneous catalysts for cycloaddition of CO₂ with epichlorohydrin under mild conditions

Converting CO₂ into useful chemical materials has uniquely high value in both chemical and resource-oriented sense. In this work, several kinds of bifunctional polyacrylonitrile fiber catalysts were developed and applied to selectively catalyze the fixing of CO₂ with epichlorohydrin. Compared to the synergistic effect, the surface polar effect is the major influence factor for the catalytic activity of the fiber catalyst, which is different from other support catalysts and has been explained detailly in this work. Among the synthesized fiber catalysts, benzylamine and N,N’-dimethyl-N-(4-pyridyl)-1,3-propanediamine (DA) bifunctionalized fiber (PAN_BDF) has excellent high catalytic activity for its lower polar microenvironment. Different PAN_BDFs with various benzylamine and DA modified degrees were prepared to inspect the influences of benzylamine and DA amounts on the catalytic activity. PAN_BDF (benzylamine and DA modified degrees are 0.93 mmol/g and 0.16 mmol/g, respectively) can complete the reaction of epichlorohydrin and CO₂ (97% conversion) under 0.1 mol% catalyst dosage at 80 °C with a CO₂ balloon. Under very low catalyst amount (0.0125 mol%), it can also effectively catalyze the reaction with 56% conversion and the TOF reaches up to 9333.3 h⁻¹. Furthermore, the fiber catalyst can be reused at least five times which indicates a potential to value-added chemistry.