This review systematically summarizes and highlights recent developments on the strategy of tailoring the distribution of active species in heterogeneous catalysis, which effectively enhances the controlling of molecular weight distribution, branch distribution, as well as chain entanglements. The application of different spectroscopic methods for assisting the design of heterogeneous catalysts is also introduced.

Abstract

Heterogeneous catalysis is the most widely used process for ethylene polymerization in industry. Active site distribution is one of the crucial issues in the heterogeneous catalysis, which strongly influences the catalytic process and the microstructure of synthesized polyethylene. In this respect, aiming at an explicit understanding of the progress, the challenge and the possible future directions in the study of heterogeneous catalysis of ethylene polymerization, the recent strategies of designing heterogeneous catalysts are reviewed from the perspective of tailoring the active site distribution, where the regulation of chain structures, including molecular weight distribution, branch distribution and entanglement state, are highlighted. The in situ and operando characterizations are also reviewed for assisting the understanding of structural information in heterogeneous catalysts.