Activation of a Palladium-Based Catalyst by Hexafluoroisopropanol for Polyketone Synthesis via Homogeneous Solution Polymerization

Abstract

Polyketone (PK) is a promising material because of its superior qualities as an engineering plastic and the direct use of CO. It is typically produced using slurry polymerization techniques, which cause reactor fouling and low bulk density product. Here, solution polymerization of CO/ethene/propene with high-molecular-weight products (240.3 kDa) and high catalytic activity (36.1 kg PK·g–1 Pd·h–1) was achieved utilizing a mixture of hexafluoroisopropanol (HFIP) and methanol. Both the activity and Mw are an order of magnitude higher than those reported in the literature. HFIP was able to activate the palladium-based precatalyst without using any strong acid. The 31P NMR, single-crystal X-ray diffraction, and density functional theory analysis prove that HFIP decreased the coordination between palladium and the acetate ligands of the precatalyst without the disassociation of the acetate. Furthermore, the active centers in the HFIP system were more stable than that in the catalytic system with strong acid.