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Title: Catalytic degradation of plastic waste to chemicals and fuel as a polymer recycling method
Author: Gobin, K.
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 2004
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With the upcoming technology available today, for the conversion of waste to useful products, research in the area of thermal degradation has gained particular attention. However, the wide product distribution and the high temperatures employed in such a process makes catalytic degradation a more promising solution to the problem of plastic waste. In catalytic degradation, lower temperatures are employed and the product distribution is narrow. This eliminates the need for further processing of the fuel in order to upgrade its quality. The aim of this work is to carry out a systematic study of various industrial catalysts in a catalytic degradation system. More specifically, the influence on the yield to liquid fuel, product distribution and hence; quality and regeneration ability of the catalysts. The catalytic degradation of polyethylene over various microporous materials, zeolite-based and clay-based catalysts, was studied in a semi-batch reactor. From the zeolites, ZSM-5 resulted mostly in gaseous products and almost no coking due to its shape selectivity properties. Commercial cracking catalysts fully degraded the polymer resulting in higher liquid yield and lower coke content than their parent ultrastable Y zeolite. This confirmed the suitability of such catalysts for a polymer recycling process and its commercialisation potential, as plastic waste could be co-fed into a refinery cracking unit. Clays, Saponite and Zenith-N, a montmorillonite, and their pillared analogues were less active than zeolites, but could fully degrade the polymer. They showed enhanced liquid formation, due to their mild acidity, and lower coke formation. Regenerated pillared clays showed practically the same performance as fresh samples, but their original clays' performance deteriorated after removal of the formed coke. Although performance of the regenerated saponite was satisfactory, with the regenerated Zenith-N the structural damage was so extensive that plastic was only partly degraded.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available