Boosting Polyethylene Hydrogenolysis Performance of Ru-CeO2 Catalysts by Finely Regulating the Ru Sizes

Abstract

Hydrogenolysis is an effective method for converting polyolefins into high-value chemicals. For the supported catalysts commonly used, the size of active metals is of great importance. In this study, it is discovered that the activity of CeO₂ -supported Ru single atom, nanocluster, and nanoparticle catalysts shows a volcanic trend in low-density polyethylene (LDPE) hydrogenolysis. Compared with CeO₂ supported Ru single atoms and nanoparticles, CeO₂ -supported Ru nanoclusters possess the highest conversion efficiency, as well as the best selectivity toward liquid alkanes. Through comprehensive investigations, the metal-support interactions (MSI) and hydrogen spillover effect are revealed as the two key factors in the reaction. On the one hand, the MSI is strongly related to the Ru surface states and the more electronegative Ru centers are beneficial to the activation of CH and CC bonds. On the other hand, the hydrogen spillover capability directly affects the affinity of catalysts and active H atoms, and increasing this affinity is advantageous to the hydrogenation of alkane species. Decreasing the Ru sizes can promote the MSI, but it can also reduce the hydrogen spillover effect. Therefore, only when the two effects achieve a balance, as is the case in CeO₂ -supported Ru nanoclusters, can the hydrogenolysis activity be promoted to the optimal value.

Keywords: Ru-CeO 2; hydrogen spillover; hydrogenolysis; metal-support effect; size effect.