Acid Treatment on Bentonite Catalysts for Alkylation of Diphenylamine

Dialkylated diphenylamine, renowned for its exceptional thermal stability and antioxidant activity, are extensively used as antioxidants. Raw bentonite after acid-treatment was carried out and the catalytic performance of various solid acid catalysts was tested, and acid-treated clay exhibited the best. In addition, the relationship between catalytic activity and washing times has been explored. The results revealed that after activating by sulfuric acid and several water-treatment times, the catalytic activity and mono-selectivity of raw bentonite significantly improved. The acid-treated bentonite catalysts were investigated by BET, XRF, XRD, SEM, Raman and FT-IR, and results indicated that the Si/Al ratio and the specific surface area increased and the basal spacing was expanded after acid and water treatment. Finally, the deactivation (reusability and regeneration) of catalysts was studied, after characterized the fresh and used catalysts, the results indicated that the deactivation of catalysts was due to reduction of microporous structure and surface acidity.