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The effect of ZSM-5 zeolite acidity on the catalytic degradation of high-density polyethylene using simultaneous DSC/TG analysis

Paper ID Volume ID Publish Year Pages File Format Full-Text
41108 45877 2012 9 PDF Available
Title
The effect of ZSM-5 zeolite acidity on the catalytic degradation of high-density polyethylene using simultaneous DSC/TG analysis
Abstract

In the present work, simultaneous thermogravimetric (TG) and differential scanning calorimetric (DSC) analyses were used to investigate the effect of the acidity of HZSM-5 zeolites on the catalytic degradation of high-density polyethylene (HDPE). The acidity of the zeolite was modified by ion exchange with sodium. The results obtained using HZSM-5 zeolites of varying acid strengths show the effect of increasing the acidity on the reduction of the degradation temperature. The addition of sodium to HZSM-5, by ion exchange, results in a decrease of the acid strength of the catalyst and an increase in the observed degradation temperature from 402 to 465 °C.The simultaneous use of the signals from the TG and DSC allowed the development of a kinetic model that is able to accurately describe all the runs performed, both the thermal and the catalytic degradation of the polymer. The kinetic parameters obtained clearly revealed the reduction in the activation energy due to the presence of the catalyst and its relation to the overall acidity of the samples. The gases evolved from the pyrolysis of polyethylene were also analysed using gas chromatography, and it was also found that volatile product selectivity changes with the catalyst acidity.The fact that the overall activity for the catalytic cracking of HDPE on these zeolites varies with internal acid strength of the zeolite indicates that the inner surface of these zeolites participates in this reaction despite the fact that the reactant molecules are extremely large.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (146 K)Download as PowerPoint slideHighlights► Acidity of the zeolite influences the degradation temperature. ► Increase in acidity implies a decrease in the computed activation energy. ► Catalytic degradation is related to internal acid strength.

Keywords
High-density polyethylene (HDPE); ZSM-5 zeolite; Kinetic modelling; Acid catalysis; Catalytic degradation; Differential scanning calorimetry (DSC); Thermogravimetry (TG)
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The effect of ZSM-5 zeolite acidity on the catalytic degradation of high-density polyethylene using simultaneous DSC/TG analysis
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 413–414, 31 January 2012, Pages 183–191
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us