Preparation and characterization of Ni/mZSM-5 zeolite with a hierarchical pore structure by using KIT-6 as silica template: an efficient bi-functional catalyst for the reduction of nitro aromatic compounds

Ni/mZSM-5 and Ni/H-mZSM-5 were synthesized as hierarchical (micro/meso porous) ZSM-5 zeolites by an
indirect template method for the first time. The resulting zeolite materials exhibited significantly enhanced
diffusional properties in comparison to purely microporous zeolite materials. The structural and
morphological characterization of the prepared catalysts was investigated using XRD, BET, atomic
absorption spectroscopy, FT-IR, 27Al-MAS NMR, SEM, TEM, XPS and DRS-UV techniques. These
hierarchical zeolites were used as acid–metal bi-functional heterogeneous catalysts for hydride transfer
in the reduction of nitro aromatic compounds. In these reactions, NaBH4 was used as a reducing agent.
Excellent yields at room temperature and very short reaction times in aqueous media conditions were
obtained. Reusability experiments showed the excellent stability of Ni/mZSM-5 and Ni/H-mMZSM-5 and
the catalysts could be reused 7 times without much loss of activity in reduction of nitro aromatic
compounds. Surprisingly, the acid form of Ni/H-mZSM-5 showed much higher activity than that of
Ni/mZSM-5. High yield, short reaction time, green solvent (water), room temperature, no by-product,
the easy reusability of catalysts and the low amounts of catalyst required are some of the advantages of
these catalysts.