| Popis: |
SBA-15 mesoporous molecular sieves with Si/M (M= Al and/or Ga) ratio in the range 20–40 were synthesized by using Pluronic P123 as template. They were characterized by XRD, N2 adsorption and DRIFT, and their acid properties were determined by pyridine and 2,6-dimethyl pyridine adsorption. Alkylation is a sequential reaction process, in which methylation of aniline produces N-methylaniline (NMA), then N,N-dimethylaniline (NNDMA) and subsequently N,N-dimethyltoluidines (NNDMT, p- > o-). N-methylation products (NMA+NNDMA) were predominant with selectivity over 95% at 350 °C. Aniline alkylation activity has been related to the Bronsted surface acidity. Finally, the effect of several bases (pyridine, 2,6-dimethylpyridine and hexamethyldisilazane) on catalyst activity was investigated. |
