An In Situ 13C Mas NMR Study of Aniline Methylation over HY Zeolite

I.I. Ivanova, E.B. Pomakhina, Yu.G. Kolyagin, A.I. Rebrov, M. Hunger et al

12th International Congress on Catalysis, Granada, Spain, July 9-14, R117 (2000)

ABSTRACT. 13C MAS NMR has been performed in situ to investigate the mechanism of aniline alkylation with methanol on HY zeolite. Methanol-13C was used as labeled reactant. The results point to the existence of two types of strongly adsorbed methanol species with solid-like characteristics and one with liquid-like characteristics corresponding to more mobile "intra-crystalline" methanol. The strongly adsorbed species are attributed to methanol adsorption complexes with aniline and surface methoxy species, respectively. Among all the species observed, only methoxy species are shown to be responsible for aniline alkylation, which takes place in the temperature range of 373 to 523 K. The primary alkylation product is N-methylaniline. Toluidines and N-methyltoluidines are formed at 523 to 623 K after complete conversion of methanol species into N-methylaniline. Therefore, isomerization or disproportionation of N-methylaniline were proposed to account for their formation.

Laboratory of Kinetics and Catalysis