Aromatic nucleophilic substitutions on zeolites. I. Amination of anisole and phenol

Influence of the Chemical Composition upon Adsorption, Coadsorption, and Reactivity of Ammonia and Methanol on Alkali-Exchanged Zeolites

“…1,2 With such amorphous acid catalysts, reaction proceeds completely to thermodynamic equilibrium which favors trimethylamine (TMA) as product. 3,4 Under typical reaction conditions, i.e., at 623 K, a reactant ratio of 1.9 (NH 3 :MeOH), and 99.8% MeOH conversion, the equilibrium composition of the products consists of 15.1% monomethylamine (MMA), 22.8% dimethylamine (DMA), and 62.1% TMA. 5 Because the global demand for TMA is the lowest, 6 it is usually recycled with excess NH 3 to enrich the product stream with mono-and disubstituted amines.…”

“…Although a number of zeolites were tested, early results showed only a minor gain in selectivity toward MMA and DMA at MeOH conversions above 90%. − Over the past decade, however, substantial improvement was achieved through tailoring of the zeolite pores and their acidity. The selectivity by geometric constraints − and the chemical composition of a given molecular sieve were reported to markedly influence product distribution. ,− Ashina et al …”

“…The selectivity by geometric constraints [14][15][16][17][18][19][20] and the chemical composition of a given molecular sieve were reported to markedly influence product distribution. 4,[21][22][23] Ashina et al 4 showed that for partially alkali-exchanged mordenites a linear correlation exists between the alkali metal cation concentration and the selectivity toward lower substituted methylamines. Similarly, Weigert 23 reported enhanced MMA and DMA selectivity when using sodium mordenite.…”