Heterogeneously supported active Pd(0) complex on silica mediated by PEG as efficient dimerization catalyst for the production of high energy density fuel

Abstract

High energy-density hydrocarbon fuels are the key materials for aircraft to increase payload and expand flight distance. Under the catalysis of atomically dispersed Pd(0) complex, saturated hexacyclic exo-exo product with good fuel property can be synthesized via co-dimerization of norbornadiene (NBD) with quadricyclane (QC). But the fragile coordination state of homogeneous Pd(0) complex limited its application in fuel production. In this work, Pd(0) complex has been heterogeneously supported on silica support with the regulation of polyethylene glycol (PEG) to increase its stability and recyclability with limited sacrifice of the activity and dimer selectivity. The structure of silica support was tuned to achieve the proper interaction with PEG and Pd(0) complex. The chain length and concentration of PEG were adjusted to further optimize the state of Pd(0) complex on silica. The as-developed heterogeneous Pd(0) complex supported on dendritic mesoporous silica nanospheres regulated by PEG2000 exhibited superior performance for the production of high energy density fuel through selective NBD-QC co-dimerization.