Ionic liquid-complex Pd/C system as catalyst for copolymerization of CO and styrene

Abstract

The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones (PK)was studied in the N-valeronitrile-N′-methylimidazolium hexafluorophosphate ([C₄CNmim]⁺PF₆ ^-) medium. The synthesized PK was characterized by Fourier transform infrared(FTIR), elemental analysis, ¹³C-nuclear magnetic resonance (¹³C-NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and gel permeation chromatography (GPC). The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt% (0.1 g ionic liquid / 1 g active carbon carrier) and the theoretical content of Pd²⁺ is 5wt% (0.05 g Pd²⁺/ 1 g active carbon carrier), the highest catalytic activity 2 963.64 gSTCO/(gPd · h) is achieved with the molecular weight and polydispersity index of PK as M _n = 9 684, M _w = 13 452 and M _w/M _n = 1.389.

Keywords

supported ionic liquid / Pd/C catalyst / copolymerization / polyketones

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