Nanosponge Hierarchical Micro-Mesoporous Mfi Zeolites as a High-Performance Catalyst for the Hydroamination of Methyl Acrylate with Aniline
Zeolites catalyze the hydroamination of alkenes, alkynes and dienes, yielding valuable amines, enamines and imines with high efficiency and chemoselectivity ( i.e., Markovnikov or anti -Markovnikov products) thanks to the architecture of their pore system and to their Brønsted-to-Lewis acid sites ratio. However, their micropores impose mass-transfer constraints on reaction rates. Nevertheless, the high external surface area of hierarchical micro-mesoporous zeolites should enable them to outperform conventional zeolites. To test our hypothesis, we compared the activity of hierarchical MFI zeolites of different crystal morphologies ( i.e., nanosponge, nanosheet and microcrystalline desilicated samples) with that of conventional medium- ( MFI ) and large-pore ( MOR and Beta) zeolites in the hydroamination of methyl acrylate with aniline. The results showed that nanosponge MFI had the highest activity (TOF= 32.9 h -1 ), reaching 57% yield of the anti -Markovnikov adduct N-[2-(methoxycarbonyl)ethyl]aniline. Furthermore, our kinetic study revealed a pseudo-second-order rate law with respect to aniline over the most active nanosponge MFI catalyst, with an apparent activation energy of 68.9 kJ/mol. The high external surface of this catalyst (371 m 2 /g) and its developed inter-crystalline mesopores (4.8 nm) suggest a kinetic-driven hydroamination reaction. Therefore, hierarchical nanosponge aluminosilicate MFI zeolites stand out as promising heterogeneous catalysts of hydroamination reactions involving bulky substrates
Year of publication: |
[2022]
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Authors: | Zhang, Yuyan ; Shamzhy, Mariya ; Kubů, Martin ; Cejka, Jiri |
Publisher: |
[S.l.] : SSRN |
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