A simple route to synthesize mesoporous ZSM-5 templated by ammonium-modified chitosan

Uniform mesoporous zeolite ZSM-5 crystals have been successfully fabricated through a simple hydrothermal synthetic method by utilizing ammonium-modified chitosan and tetrapropylammonium hydroxide (TPAOH) as the meso- and microscale template, respectively. It was revealed that mesopores with diameters of 5-20nm coexisted with microporous network within mesoporous ZSM-5 crystals. Ammonium-modified chitosan was demonstrated to serve as a mesoporogen, self-assembling with the zeolite precursor through strong static interactions. As expected, the prepared mesoporous ZSM-5 exhibited greatly enhanced catalytic activities compared with conventional ZSM-5 and Al-MCM-41 in reactions involving bulky molecules, such as the Claisen-Schmidt condensation of 2-hydroxyacetophenone with benzaldehyde and the esterification reaction of dodecanoic acid and 2-ethylhexanol. Mesoporous zeolite: Ammonium-modified chitosan served as a mesoporogen in the hydrothermal synthesis of mesoporous zeolite Socony Mobil (ZSM)-5, self-assembling with the zeolite precursor through strong static interactions (see figure; TPA=tetrapropylammonium, HTCC=N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride).