Bivalent copper oligopyrocatecholate as a novel heterogeneous catalyst for the oxidative degradation of mercaptan in caustic solution: Synthesis, characterization, and kinetic study

Abstract

A novel catalyst based on bivalent copper oligopyrocatecholate was first successfully synthesized and dispersed in a polymer matrix for oxidative degradation of mercaptan in aqueous caustic solution. X-ray diffraction analysis has demonstrated that the synthesized catalyst was a crystalline phase with a minimum amorphous component. Mechanism analysis and kinetic experiments were conducted to investigate the kinetic mechanism of the reaction of isopropyl mercaptan oxidation catalyzed by copper oligopyrocatecholate dispersed in a polymer matrix. The influences of temperature, initial concentrations of reactants, and catalytic surface area on the reaction rate were studied to obtain the rate expression of intrinsic kinetics. The research results showed that the subsequent electron-transfer step was the rate-limiting step of the reaction. Additionally, the mercaptan oxidation rate in caustic solution was inversely proportional to the first power of the alkali concentration. The apparent activation energy was approximately 27.71 ± 1.12 kJ/mol. Importantly, this rate law for mercaptan oxidation can be used to design industrial reactors for the light oil sweetening process.