Enhanced catalytic properties of rhodium nanoparticles deposited on chemically modified SiO2 for hydrogenation of nitrile butadiene rubber

Abstract

An efficient and recyclable catalyst was prepared by depositing rhodium nanoparticles (Rh NPs) on a SiO₂ support with the surface modified by 3-aminopropyl-trimethoxysilane (APTS). The obtained catalyst, Rh(III)/MSiO₂, was extensively characterized by FTIR, SEM, XRD, XPS, BET, and ICP to demonstrate the incorporation of amine groups on the surface of the modified SiO₂. The hydrogenation of acrylonitrile butadiene rubber (NBR) was used to evaluate the catalytic properties of Rh(III)/MSiO₂, and a 98.68% conversion and nearly 100% selectivity to CC were obtained under optimum conditions (120 °C, 3.0 MPa H₂, 8 h). A comparative study was made between Rh(III)/MSiO₂ and Rh(III)/SiO₂ in the hydrogenation of NBR, and Rh(III)/MSiO₂ showed higher activity and higher stability. The results indicated that the increase of the amount of deposited metal particles and the improvement of the adhesion of metal particles to the support are the reasons for the high performance of Rh(III)/MSiO₂. In addition, the Rh(III)/MSiO₂ could be easily recovered by centrifugation and reused 3 times with only a slight loss in activity and selectivity. Furthermore, this modified method can be extended to other heterogeneous catalyst systems to improve their activity, recyclability and stability.