Zeolite-supported catalyst for the N-methylation of amines.

A great deal of attention has been focused on the N-containing compounds, especially amines, owing to their wide application in the pharmaceuticals, dyes, agrochemical, and polymer industries. Among the various primary amine derivatives, tertiary amines hold significant attention because of their potential application as key pharmaceutical ingredients. The heterogeneous reductive N-methylation process using H2 and HCHO as reductant and C1 source has garnered significant attention, avoiding the use of hazardous chemicals such as silanes, LiAlH4, NaBH4, along with advantages such as easy product separation, H2O as the only side product. In this regard, the present study focuses on the development of Pd supported on H-ZSM-5 based catalytic system for the reductive N-methylation of aniline to produce N,N-dimethylaniline selectively. The role of metal nanoparticles towards the H2 activation and zeolite support contributing to surface acidic sites that facilitate the intermediate adsorption via C=N activation, has been investigated using CO-pulse, DRIFT, and NH3-TPD studies. In addition, the catalyst has been explored through various characterization techniques, such as H2-TPR, XPS, BET, HR-TEM, XRD analysis, and poisoning studies, which will provide in-depth insights into the specific role played by acid sites, especially the Bronsted acid sites, in efficiently converting primary amines to tertiary amines.