- Postgraduate Fellow, Department of Chemistry, Covenant University, Ogun State, Nigeria
Special properties inherent to zeolites in facilitating the construction of novel upramolecular assemblies by encapsulation of guest molecules (metal complexes) into their large cages can be utilized to use these assembled materials as novel catalysts. These modified solids have the advantages of both behaving as the homogeneous and the heterogeneous catalytic system. In the present work, copper (II) and cobalt (II) complexes of 2-amino ethanoic acid (2-AEA) encapsulated in the cages of zeolite-Y have been prepared utilizing Flexible Ligand Synthesis technique. Both these solids (catalysts) including their precursors NaY, CuY and CoY are characterized for their analytical, textural, spectral and orphological behaviour. Based on the physicochemical measurements, it is established that the successful encapsulation of Cu(2-AEA) and Co(2-AEA) complexes inside the cages of zeolite-Y has taken place. This is also confirmed by BET studies of the encapsulated species whose surface area and pore volume are found to decreased by the uptake of Cu(2-AEA) and Co(2-AEA) complexes. All these observations confirm the location of the complexes in the cages of zeolite-Y. These encapsulated species can be used as catalysts because of the free coordination site available in the cages. Both the catalysts including all their precursors have also been screened for catalyzing the oxidation of phenol using 30% H2O2 as an oxidant. Performing several sets of experiments, reaction parameters, such as oxidant- substrate ratio, temperature, type of solvents and concentration of catalysts have been optimized to obtain the maximum conversion of phenol to p-CAT (p-Catechol) and HQ (Hydroquinone). Blank reaction was also carried out under the similar optimized conditions. The catalytic activity followed the order: [Co-2-AEA]Y (28.70%) > [Cu-2-AEA]Y (25.20) > Cu-Y (20.60)> Co-Y (13.60) >Na-Y (4.90) > Blank (0.60) after 12 h of reaction time at 80°C in acetonitrile medium. It is concluded that the encapsulated catalysts [Co-2-AEA]Y (28.70%) > [Cu-2-AEA]Y (25.20) are highly active in comparison to their simple ion exchanged precursors.
Keywords: Zeolite-Y, Cu(II)Y, Co(II)Y, 2-amino ethanoic acid, phenol oxidation”
[This article belongs to Journal of Catalyst & Catalysis(jocc)]
1. Drechsel, S. M., Kaminski, R. C., Nakagaki, S., et.al. Encapsulation of Fe (III) and Cu (II) complexes in NaY zeolite. Journal of colloid and interface science. 2004; 277(1): 138-145.
2. Chavez-Rivas, F., Rodríguez-Fuentes, G., Berlier, G., et.al. Evidence for controlled insertion of Fe ions in the framework of clinoptilolite natural zeolites. Microporous and mesoporous materials. 2013; 167: 76-81.
3. Chandrakar, A. K., Dewangan, G. P., Chandraker, N., et.al. Zeolite Encapsulated Metal Complexes and Their Catalytic Activities: An Overview. International Journal of Advanced Research in Chemical Science (IJARCS). 2015; 2(7): 1-6.
4. Vincent, J. B., Olivier-Lilley G. L., Averill, B. A. Proteins containing oxo-bridged dinuclear iron centers: a bioinorganic perspective. Chemical Reviews. 1990; 90(8): 1447-1467.
5. Chatterjee, D., Bajaj, H. C., Das, A., et.al. First report on highly efficient alkene hydrogenation catalysed by Ni (salen) complex encapsulated in zeolite. Journal of molecular catalysis. 1994; 92(3): L235-L238.
6. Weckhuysen B. M., Verberckmoes A. A., Fu L., et.al. Zeolite-encapsulated copper (II) amino acid complexes: synthesis, spectroscopy, and catalysis. The Journal of Physical Chemistry. 1996; 100(22): 9456-9461.
7. Jacob C. R., Varkey S. P., Ratnasamy P. Oxidation of para-xylene over zeolite-encapsulated copper and manganese complexes. Applied Catalysis A: General. 1999; 182(1): 91-96.
8. Herron N., Farneth W. E. The design and synthesis of heterogeneous catalyst systems. Advanced Materials. 1996; 8(12): 959-968.
9. Bedioui F. Zeolite-encapsulated and clay-intercalated metal porphyrin, phthalocyanine and Schiff-base complexes as models for biomimetic oxidation catalysts: an overview. Coordination Chemistry Reviews. 1995; 144: 39-68.
10. Viswanathan B. Catalytic alkylation of aromatic substrates—Part II. Bull. Catal. Soc. India. 2000; 10(1).
11. Hosseini-Ghazvini S. M. B., Safari P., Mobinikhaledi A., et.al. Flexible ligand synthesis and characterization of a host (a copper (II) tetradentate Schiff base)/guest (zeolite NaY) nanocomposite material: an efficient and reusable catalyst for the selective hydroxylation of phenol. Reaction Kinetics, Mechanisms and Catalysis. 2015; 115(2): 703-718.
12. Varkey S. P., Ratnasamy C., Ratnasamy P. Zeolite-encapsulated manganese (III) salen complexes. Journal of Molecular Catalysis A: Chemical. 1998; 135(3): 295-306.
13. Abraham R., Yusuff K. K. M. Copper (II) complexes of embelin and 2-aminobenzimidazole encapsulated in zeolite Y-potential as catalysts for reduction of dioxygen. Journal of Molecular Catalysis A: Chemical. 2003; 198(1-2): 175-183.
14. Jin C., Fan W., Jia Y., et.al. Encapsulation of transition metal tetrahydro-Schiff base complexes in zeolite Y and their catalytic properties for the oxidation of cycloalkanes. Journal of Molecular Catalysis A: Chemical. 2006; 249(1-2): 23-30.
15. Modi C. K., Trivedi P. M., Chudasama J. A., et.al. Zeolite-Y entrapped bivalent transition metal complexes as hybrid nanocatalysts: density functional theory investigation and catalytic aspects. Green Chemistry Letters and Reviews. 2014; 7(3): 278-287.
16. Novikova G. V., Petrov A. I., Staloverova N. A., et.al. Complex formation of Sn (II) with glycine: An IR, DTA/TGA and DFT investigation. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2015; 135, 491-497.
17. Nethravathi B. P., Mahendra K. N., Reddy K. R. K. Zeolite-encapsulated 2-(o-aminophenyl) benzimidazole complexes: synthesis, characterization and catalytic activity. Journal of porous Materials. 2011; 18(3): 389-397.
18. Nethravathi B. P., Manjunathan P., Mahendra K. N. Copper complex of isatin Schiff base encapsulated in zeolite as active heterogeneous catalyst: an efficient protocol for the acetylation reaction. Journal of Porous Materials. 2016; 23(5): 1305-1310.
19. Nakomoto K. Infrared and Raman spectra of inorganic and coordination compounds. 4 th ed. U S: Wiley-Blackwell; 1986.
20. Ghorbanloo, M., Ghamari, S., Shahbakhsh, N., et.al. (2014). Diaquabis (L-phenylalaninato) nickel (II) encapsulated in zeolite: an efficient heterogeneous catalyst system for the oxidation of cyclohexene, toluene and ethyl benzene. Journal of the Brazilian Chemical Society. 2014; 25(11): 2073-2079.
21. Bania K. K., Deka R. C. Zeolite-y encapsulated metal picolinato complexes as catalyst for oxidation of phenol with hydrogen peroxide. The Journal of Physical Chemistry C. 2013; 117(22): 11663-11678.
22. Mori K., Yamashita H. Metal Complexes Supported on Solid Matrices for Visible‐Light‐Driven Molecular Transformations. Chemistry–A European Journal. 2016; 22(32): 11122-11137.
23. Achard T. R., Clutterbuck L. A., North M. Asymmetric catalysis of carbon-carbon bond-forming reactions using metal (salen) complexes. Synlett, 2005; 12: 1828-1847.
24. Zhou X. F. Catalytic oxidation and conversion of kraft lignin into phenolic products using zeolite‐ encapsulated C u (II)[H 4] salen and [H 2] salen complexes. Environmental Progress & Sustainable Energy. 2015; 34(4): 1120-1128.
25. Salavati-Niasari M., Fereshteh Z., Davar F. Synthesis of oleylamine capped copper nanocrystals via thermal reduction of a new precursor. Polyhedron. 2009; 28(1): 126-130.
26. Rimoldi M., Howarth A. J., DeStefano M. R., et.al. Catalytic zirconium/hafnium-based metal– organic frameworks. ACS Catalysis. 2017; 7(2): 997-1014.
27. Cole-Hamilton D. J. Homogeneous catalysis–new approaches to catalyst separation, recovery, and recycling. Science. 2003; 299(5613): 1702-1706.
28. Godhani D. R., Nakum H. D., Parmar D. K., et.al. Zeolite Y encaged Ru (III) and Fe (III) complexes for oxidation of styrene, cyclohexene, limonene, and α-pinene: An eye-catching impact of H2SO4 on product selectivity. Journal of Molecular Catalysis A: Chemical. 2017; 426: 223-237.
29. Bania K. K., Deka R. C. Experimental and theoretical evidence for encapsulation and tethering of 1, 10-phenanthroline complexes of Fe, Cu, and Zn in Zeolite–Y. The Journal of Physical Chemistry C. 2012; 116(27): 14295-14310.
|Received||April 7, 2021|
|Accepted||May 4, 2021|
|Published||May 15, 2021|