Physico-chemical studies and CO adsorption on zeolite-encapsulated MnII, MnIII–hydrazone complexes

Complexes of Mn(II) and Mn(III) with N2O3 hydrazone ligand derived from salicylaldehyde and benzenesulphonylhydrazide have been encapsulated in zeolite Y- supercages by a diffusion method. The synthesized new materials have been characterized by combination of elemental analysis, FT-IR, UV–vis., magnetic measurements, XRD, thermal analysis (TG, DTG and DTA), as well as surface area measurements and nitrogen adsorption studies. Investigation of the stereochemistry of these incorporated chelates pointed out that, Mn(II) complex is tetrahedral with involvement of zeolite oxygen in coordination meanwhile Mn(III) complex has octahedral configuration without contribution of the lattice oxygen. The intrazeolitic hydrazone complexes are thermally stable up to 1000 °C without decomposition. Catalytic activity towards CO adsorption for these zeolite encapsulated complexes has been investigated and compared with MnII-Y using in situ FT-IR spectroscopy. The results revealed that, MnII(SBSH)/Y and MnIII(SBSH)/Y give an elementary peak near 1728 cm−1 indicating a selectivity to form COOH species while MnII-Y catalyst gives a broad band in the region of 1765–1560 cm−1 assigned to different (COOH) and carbonates species. On the other hand, the in situ FT-IR data indicate that MnII(SBSH)/Y and MnIII(SBSH)/Y can be used as reactive catalysts in water gas shift reaction (WGSR).