Mechanistic Understanding of Methanol Carbonylation: Interfacing Homogeneous and Heterogeneous Catalysis Via Carbon Supported Ir-La

摘要

The carbonylation of methanol is one of the largest processes that is still being carried out under homogeneous catalysis. It allows to produce more than 6 million tonnes of acetic each year [1]. The energy requirements of the separation of catalyst and products, and the contamination associated to them, are considerably high for a process of this magnitude, therefore, finding and understanding the fundamentals of a heterogeneous catalysis homologous process is necessary and of high importance. In this work, we report the synthesis, activity and characterization of a carbon-supported Ir-La catalyst which exhibited high activity and selectivity towards acetyls for methanol carbonylation, compared to the unpromoted carbon-supported Ir catalyst, as well as the homogenous Ir-Ru catalyst and a heterogeneous analog carbon-supported Ir-Ru catalyst [2]. The work focuses and answers two questions [3]: 1) what is the reaction mechanism and 2) what is the role La plays on the catalyst. To provide information about these questions, X-ray photoelectron spectroscopy (XPS), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), in situ attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy, density functional theory (DFT) and ab initio molecular dynamics (AIMD) were used.