PdGa/TiO2 an efficient heterogeneous catalyst for direct methylation of N-methylaniline with CO2/H2
An effective sustainable heterogeneous PdGa/TiO2 catalyst was prepared for direct methylation of N-methylaniline with CO2/H2 to N,N-dimethylaniline. The PdGa/TiO2 catalyst exhibited 98% conversion and 94% selectivity under the reaction conditions (180 °C, 5 MPa H2, 5 MPa CO2, 10 h), which are one of the best results reported to date for the heterogeneous N-methylation with CO2 as methylation reagent over the supported metal catalysts. The PdGa/TiO2 catalyst was well characterized using TEM, TPR, XPS, CO-adsorption IR studies and high-pressure in situ FTIR studies. It was confirmed that PdGa bimetallic alloy nanoparticles were formed and highly dispersed on the TiO2 support, and the electron-deficient Pd derived from the interaction with Ga could activate CO2 and transform it to formic acid, which is the key step for the discussed methylation, and high activity was obtained over the PdGa/TiO2 catalyst. The activating properties of the PdGa/TiO2 catalyst will open a new route for transfer and utilization of CO2 in the fields of energy and environmental fields.