Faculty Advisor or Committee Member

Michael T. Timko, Advisor

Faculty Advisor or Committee Member

N Aaron Deskins, Committee Member

Faculty Advisor or Committee Member

Ravindra Datta, Committee Member

Faculty Advisor or Committee Member

Aaron R. Sakulich, Committee Member

Identifier

etd-042417-152309

Abstract

Waste plastic treatment was a global issue currently. A sustainable recycling process was required to recovery the monomer units from the polymer, thus avoiding environmental impacts due to disposal and enhancing the economic benefit from the recovered products. Pyrolysis was one of the promising process and previous MQP group has studied the pyrolysis with molten salts. In this work, a standardized and optimized pyrolysis reaction process of polystyrene was developed, based on the previous work on molten salt pyrolysis 5. The literature of pyrolysis mechanism and catalytic effects were reviewed as a guide process design. The orientation of the reactor was standardized to be consistent with literature record of preceding work. The positioning of the flow tube for the carrier gas and thermocouple were standardized in locations to provide mixing process of the reactant, the removal of products, and the accurate measurement of reaction temperature. The product collection system was also investigated and optimized to maximize collection efficiency while avoiding excessively low temperatures. The experiment results with standardized reaction configuration showed an improved styrene yield, 65%, compared with a previous yield of 44%. Then with the standardized reaction configuration, the catalytic effects of molten salt were studied at 400℃ pyrolysis temperature. Quantitative analysis indicated that the molten salt improved the styrene selectivity of the monomer compared to the dimer. Analysis of product composition and mass balance indicated formation of heavy non-GC detectable species in the liquid products. Gas phase secondary reaction during pyrolysis, and re-polymerization inside the liquid products, were discussed to explain the different styrene yield and the existence of heavy species. Based on the current results, recommendations for the pyrolysis temperature, initial reactants loading, and condenser temperature and analysis strategies were provided for further study of the molten salt pyrolysis of polystyrene.

Publisher

Worcester Polytechnic Institute

Degree Name

MS

Department

Chemical Engineering

Project Type

Thesis

Date Accepted

2017-04-24

Accessibility

Restricted-WPI community only

Subjects

GC-MS, GC, styrene, recycling, Plastic waste, polystyrene, optimization, Pyrolysis

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