Phosphorylated Polyacrylonitrile Fibers as an Efficient and Greener Acetalization Catalyst

A novel solid acid catalyst (PAN_EAPF) is developed by immobilization of phosphoric acid on polyacrylonitrile fiber through covalent bonding. Various characterization techniques such as elemental analysis (EA), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), etc. are utilized to confirm the successful grafting and the stability of the fiber catalysts during application. PAN_EAPF shows high catalytic activity in the acetalization of aldehydes owing to the high utilization efficiency of its functionalized acid sites. In addition, the strong polarity micro‐environment in the surface layers of PAN_EAPF make it highly suitable for catalytic application in both water and alcohol. Furthermore, the fiber catalyst can be applied to the acetalization of aldehydes in a continuous‐flow process at room temperature, and shows excellent reactivity and superior recyclability (over 20 times). The many advantages of PAN_EAPF such as simple preparation, convenient regulation of acid amount, high durability, and eco‐friendly process make it very attractive for fixed‐bed reactors in the chemical industry.