Abstract
Manganese (II)-, (III)-complexes with NO3 Schiff base ligand (SPAB) derived from salicylaldehyde and p-aminobenzoic acid have been synthesized and immobilized in the zeolite-Y supercages by a flexible ligand method. The synthesized new host/guest materials have been characterized by various physicochemical techniques, in addition to surface area measurements and nitrogen adsorption studies. Investigation of the stereochemistry of these incorporated chelates elucidated that, Mn(II) complex is tetrahedral with involvement of zeolite oxygen in coordination meanwhile Mn(III) complex has octahedral configuration with Jahn-Teller distortion but without contribution of the lattice oxygen. The intra-zeolitic Schiff base complexes are thermally stable up to congruent to 600 degrees C without any decomposition. Catalytic activity towards CO adsorption for zeolite-encapsulated complexes has been investigated and compared with Mn-II-Y using in situ FT-IR spectroscopy. The results pointed out that, encapsulation of manganese (II, III) complexes in zeolites enhances remarkably the selectivity towards the formation of unionized carboxyl (-COOH) species which is considered a characteristic property of the zeolite encapsulated Mn(II,III)-SPAB complexes over Mn-II-Y. On the other hand, the in situ FT-IR data demonstrate that Mn-II(SPAB)/Y and Mn-III(SPAB)/Y can be used as reactive catalysts in water gas shift reaction (WGSR). (C) 2010 Elsevier B.V. All rights reserved.