Thermal desorption-degradation of cyclohexylamine over Ni2+- and Al3+-exchanged bentonite studied using evolved gas analysis (TG-EGA) and diffuse reflectance spectroscopy (DRIFTS)

BREEN, C., FORSYTH, J., YARWOOD, J. and HUGHES, T. (2000). Thermal desorption-degradation of cyclohexylamine over Ni2+- and Al3+-exchanged bentonite studied using evolved gas analysis (TG-EGA) and diffuse reflectance spectroscopy (DRIFTS). Physical Chemistry Chemical Physics, 2 (17), 3887-3892.

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Link to published version:: 10.1039/b003587o

Abstract

Ni2+- and Al3+-exchanged montmorillonite are known to demonstrate Lewis and Bronsted acidity, respectively, when probed using the diagnostic base pyridine (C. Breen, Clay Miner., 1991, 26, 487). Thermogravimetric analysis (TGA) of pyridine saturated Al3+- and Ni2+-montmorillonite differ whereas here it was found that cyclohexylamine (CHA) desorption profiles were very similar, albeit CHA was held to a higher temperature on Ni2+-SWy-2 than on Al3+-SWy-2. Evolved gas analysis (EGA) of the desorbed products revealed significant differences in the amount of cyclohexylamine, cyclohexene, methylcyclopentene, benzene and aniline produced, which demonstrated different decomposition pathways for CHA sorbed to Al3+- and Ni2+-exchanged SWy-2. For example, cyclohexene is produced over both exchange forms whereas aniline and methylcyclopentene were the major products over Ni2+- and Al3+-SWy-2, respectively. Variable-temperature DRIFTS was unable to distinguish between CHA-treated Al3+- and Ni2+-SWy-2 at temperatures < 250 degrees C, but at 300 degrees C the Ni2+ form exhibited a strong, intense band at 1648 cm(-1) which identifies cyclohexylimine as a surface bound intermediate which transforms before desorption.

Item Type: Article
Research Institute, Centre or Group: Materials and Engineering Research Institute > Polymers Nanocomposites and Modelling Research Centre > Polymers, Composites and Spectroscopy Group
Identification Number: 10.1039/b003587o
Depositing User: Jill Hazard
Date Deposited: 14 May 2010 13:16
Last Modified: 28 Sep 2010 17:12
URI: http://shura.shu.ac.uk/id/eprint/1838

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