Amination of 2-Methylpropene over Proton-Exchanged ZSM-5 Zeolite Catalysts

Article abstract of DOI:10.1016/0021-9517(94)90028-0

The reaction between 2-methylpropene and ammonia over various zeolite catalysts having a wide range of silica/alumina ratios from 5.6 to 1340, and over solid acid catalysts (CsxH3-xPW12O40 (x = 0.15, 0.5), SiO2-Al2O3, and SiO2-TiO2) and the solid base MgO was investigated.The significant decrease of activity following substitution of Na⁺ for H⁺ in H-MFI-40 or by preadsorption of diisopropylamine showed that amination is catalyzed by the acid sites.A similar change in the catalytic activity of H-MFI-40 with the number of Broensted acid sites at elevated temperatures, as well as the appearance of activities of CsxH3-xPW12O40 (x = 2.5, 2.85), which has only Broensted acid sites, indicated amination on the Broensted acid site.The dependence of conversion into t-butylamine, the number of Broensted acid sites, and the turnover frequencies on the SiO2/Al2O3 ratio suggested that the number and strength of the Broensted acid sites are the factors controlling the title reaction.Due to the above two factors having the proper values, proton-exchanged ZSM-5 zeolite with a silica/alumina ratio of 81 was the most active for amination among the catalysts tested.