Immobilized amino-containing basic ionic liquid on graphene oxide as an efficient and stable catalyst for transesterification

Abstract

A basic ionic liquid containing aminopropylimidazolium moiety and OH‒ anion was immobilized on silane-functionalized graphene oxide (GO) by a condensation process, followed by an anion-exchange reaction. The properties of the resulting GO-[Ap-im]OH material were characterized using extensive techniques including FTIR, XPS, AFM, TGA, etc. The material could be used as a transesterification catalyst, affording the expected ester products in good yields under mild reaction conditions. This GO-[Ap-im]OH material with amino groups shows higher activity than GO-[Ap-im]Cl without amino groups. Furthermore, this catalyst could easily be separated from the reaction mixture by filtration and recycled at least 6 times without a noticeable decrease in the catalytic activity. The prominent performance of GO-[Ap-im]OH is attributed to the enhanced basicity of combining amine groups and OH‒ anions as well as less mass-transfer resistance of laminar GO.