Synthesis of N-methylaniline by Aniline Alkylation with Methanol over Sn-MFI Molecular Sieve

Sn-MFI molecular sieves (Tin silicalite-1) with SiO2/SnO2 molar ratio of 50–150 were synthesized and characterized. Elemental analysis, XRD and DRUV–vis confirmed that prepared samples were of MFI zeolite structure and Sn was incorporated in MFI framework. Vapor phase methylation of aniline over Sn-MFI was systematically studied and optimizations of process parameters were carried out. Sn-MFI (SiO2/SnO2 = 50) was found to be optimum catalyst with 55% aniline conversion and 60% N-methylaniline selectivity. At lower space velocity (higher contact time) of 1 h−1, aniline conversion was found to be increased to 71% with reduction in N-methylaniline selectivity to 39% and increased in N,N-dimethylaniline selectivity to 58%. The reaction follows first order kinetics with respect to aniline having activation energy of 7.3 kcal/mol.