Skip navigation
Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/2533
Title: Preparation of bipolar zeolite exchangers by gas-phase modification using NOx
Authors: Shaikh R.G.
Shukla A.
Sinha, Shishir N.
Kumar J.
Kumar A.
Published in: Chemical Engineering Science
Abstract: Zeolites with varying Si/Al ratio, were synthesized using silica and alumina powder and by matching the XRD patterns with those given in the JCPDS files their chemical formula and crystal structure were determined. In order to make these into bipolar zeolite exchangers, they were modified (called Z2 zeolite) using a gas-phase reaction with NOx at 225°C and the formation of the oxynitride groups was confirmed with FTIR, ESCA and the elemental analysis. The XRD patterns of the modified zeolites were found to have changed and did not match with any of the patterns given in the JCPDS files. For these modified zeolites, we have determined the crystal structures and these were found to change from cubic for the unmodified to orthorhombic for the modified zeolites with Si/Al ?1.2 and to the tetragonal for Si/Al >1.2. The oxynitride covalent bond in Z2 zeolites could be reduced by reacting with hydrazine hydrate to give bipolar zeolite exchangers (denoted as Z3 zeolite) containing imine groups, thus making the zeolite bipolar in nature. The cation exchange capacities were determined and found to have the same order of magnitude as reported in the literature. The elemental analysis of the modified zeolites was carried out and the experimentally determined nitrogen value of 3.85 wt% gives 0.9-1.2 oxynitride group per formula unit of the material. The experimentally determined anion exchange capacity of the Z3 zeolites (1.72 meq/dry g for sample A1) suggests that for this value of exchange capacity, about two out of three formula units have an imine group. The difference between these two independent experiments suggests that not all imine groups participate in the anion exchange phenomena due to their non-availability. We found that Z3 zeolite responds to organic reactions, and can be reacted with dichloroethane and subsequently quarternized with trimethylamine. Their anion exchange capacity is found to increase significantly. © 2003 Elsevier Ltd. All rights reserved.
Citation: Chemical Engineering Science (2004), 59(3): 661-670
URI: https://doi.org/10.1016/j.ces.2003.10.010
http://repository.iitr.ac.in/handle/123456789/2533
Issue Date: 2004
Publisher: Elsevier Ltd
Keywords: Bipolar zeolite
Chemical modification
Exchangers
NOx reaction
ISSN: 92509
Author Scopus IDs: 7004584199
7202963775
7403739121
57202553043
36063155900
Author Affiliations: Shaikh, R.G., Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
Shukla, A., Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
Sinha, S., Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
Kumar, J., Material Science Programme, Indian Institute of Technology, Kanpur 208016, India
Kumar, A., Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India
Corresponding Author: Kumar, A.; Department of Chemical Engineering, Indian Institute of Technology, Kanpur 208016, India; email: anilk@iitk.ac.in
Appears in Collections:Journal Publications [CH]

Files in This Item:
There are no files associated with this item.
Show full item record


Items in Repository are protected by copyright, with all rights reserved, unless otherwise indicated.