Effect of catalyst loading on kinetics of catalytic degradation of high density polyethylene: Experiment and modelling

Sarathy, Sandeep, Wallis, Michael D. and Bhatia, Suresh K. (2010) Effect of catalyst loading on kinetics of catalytic degradation of high density polyethylene: Experiment and modelling. Chemical Engineering Science, 65 2: 796-806. doi:10.1016/j.ces.2009.09.032


Author Sarathy, Sandeep
Wallis, Michael D.
Bhatia, Suresh K.
Title Effect of catalyst loading on kinetics of catalytic degradation of high density polyethylene: Experiment and modelling
Journal name Chemical Engineering Science   Check publisher's open access policy
ISSN 0009-2509
1873-4405
Publication date 2010-01-16
Year available 2009
Sub-type Article (original research)
DOI 10.1016/j.ces.2009.09.032
Volume 65
Issue 2
Start page 796
End page 806
Total pages 11
Editor A. T. Bell
Place of publication London, U.K
Publisher Pergamon Press/Elsevier
Collection year 2011
Language eng
Formatted abstract
Catalytic degradation of high density polyethylene (HDPE) using silica-alumina has been investigated in a thermogravimetric analyser, and the degradation kinetics determined using a population balance model recently developed in our laboratory. The incorporation of multisite adsorption into the model greatly improved the fit to experimental data. It is proposed that both thermal and catalytic cracking occur simultaneously, effectively through a two-step process: cracking of the large initial polymer molecules dominated by the catalyst with an activation energy of approximately 174 kJ/mol, followed by further breakage strongly influenced by thermal cracking with an activation energy of approximately 256 kJ/mol, so that it is the thermal degradation that is especially responsible for over-cracking and formation of gaseous products. In addition, it is found that the pre-exponential factor has a linear dependence on the catalyst loading. The breakage kernel used in the model allows for random scission, with mid-point being the most probable, so that the product distribution does not comprise a single peak moving smoothly through time—but peaks form at several discrete sizes. The model can predict product distributions at various conditions; however, as the model does not incorporate any specific mechanisms for adsorption and reaction, more direct investigation of the product distributions is also needed. This is of industrial importance as these products are economically attractive for the production of liquid fuels. The required reaction time can be predicted for a specific product distribution.
© 2009 Elsevier Ltd. All rights reserved.
Keyword Adsorption
Catalytic degradation
Kinetics
Mathematical modelling
Population balance
Reaction engineering
Thermogravimetric data
Thermal-degradation
Reactive extruder
Cracking
Polymer
Conversion
Mixture
Gas
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online 25 September 2009. Corrigendum to article located at UQ:210047

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
Official 2011 Collection
 
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Created: Sun, 18 Apr 2010, 00:06:46 EST