Catalytic oxidation of limonene over zeolite-Y entrapped oxovanadium (IV) complexes as heterogeneous catalysts

• Published in: Journal of molecular catalysis. A, Chemical Vol. 395; pp. 151 - 161
• Main Authors: Modi, Chetan K., Chudasama, Jiten A., Nakum, Haresh D., Parmar, Digvijaysinh K., Patel, Arun L.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-12-2014; Elsevier
• Subjects: Catalysis; Chemistry; Exact sciences and technology; General and physical chemistry; Heterogeneous catalysts; Ion-exchange; Limonene oxidation; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; VO(IV) complexes; Zeolite-Y; Zeolites: preparations and properties; Limonene oxidation; VO(IV) complexes; Heterogeneous catalysts; Zeolite-Y; Heterogeneous catalysis; 1,8-p-Menthadiene; Catalytic reaction; Transition element complexes; Vanadium complex; Oxidation; Zeolite; Oxo complex
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2014.08.022

•The use of zeolite-Y entrapped VO(IV) complexes as heterogeneous catalysts.•The catalysts were prepared by flexible ligand (FL) technique.•Oxidation of limonene using t-butyl hydroperoxide and/or 30% H2O2 as oxidants.•[VO(VTCH)2]-Y showed higher catalytic activity (97.7%) with limonene glycol (45.1%), selectivity.•The proposed catalytic mechanism explains two possible pathways for limonene oxidation
A series of VO(IV) complexes with Schiff base ligands derived from vanillin thiophene-2-carboxylic hydrazone (VTCH), vanillin furoic-2-carboxylic hydrazone (VFCH), salicylaldehyde thiophene-2-carboxylic hydrazone (H2STCH) and/or salicylaldehyde furoic-2-carboxylic hydrazone (H2SFCH) have been synthesized as neat and their entrapped complexes into the nanopores of zeolite-Y. These materials were characterized by several techniques: chemical analysis (ICP-OES and elemental) and spectroscopic methods (FT-IR, electronic, XRD, SEMs and BET). All the prepared catalysts were tested over the liquid phase limonene oxidation reaction, using t-butyl hydroperoxide (TBHP) and/or 30% H2O2 as oxidants. Limonene glycol, carveol and carvone were the main products obtained. It was observed that zeolite-Y based entrapped complexes exhibited higher catalytic activity than neat VO(IV) complexes. These zeolite-Y based entrapped complexes are stable and recyclable under current reaction conditions. Amongst them, [VO(VTCH)2]-Y showed higher catalytic activity (97.7%) with limonene glycol (45.1%), selectivity.