In situ embedding of ultra-fine nickel oxide nanoparticles in HMS with enhanced catalytic activities of styrene epoxidation

In this paper, a new templating assemble route (S⁰M⁺I⁻) was proposed to construct a nickel-based mesoporous silica catalyst. During this method, the neutral surfactant dodecyl amine was used as a special agent for both capturing the metal ions and structure-directing of the mesoporous silica. Based on the templating assemble route, metal cations were highly enriched in the interface of micelles and silicate wall by the physiochemical interaction among the surfactant (S⁰), metal cations (M⁺, Ni²⁺) and silicate oligomers (I⁻). Besides, instead of original hydrogen-bonding, the addition of metal cations in the assemble process made the interaction between micelles and silicate oligomers improved significantly through the counterion-mediated interaction. According to these effects, highly-dispersed, ultra-fine and accessible nickel oxide nanoparticles (NPs) were in situ produced and embedded in the channels and the exposed level of the active sites on these NPs would reach to the highest. Moreover, as expected, the synthesized catalyst exhibited superior catalytic activities for the epoxidation of styrene.