Career: Catalyst-Directed Resource from Waste Polymers

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ABSTRACT CTS-9623741 Catalyst-directed resource recovery is a promising technology for the conversion of polymeric waste materials into high-valued products such as fuels and petrochemicals. However, the lack of a comprehensive knowledge base has limited its application. This research aims at developing a rigorous, science-based methodology for the recovery of high-valued products from polymeric waste using both experiment and theory. The experimental program focuses on the development of novel contacting patterns to enhance the polymer-catalyst interaction and on the identification of optimal catalyst parameters that enhance the value of the products afforded. The experimental work is complemented by a theoretical study exploiting mechanistic modeling and computational quantum chemistry to provide information about the controlling reaction fundamentals. Promising strategies for improved recovery of valuable products from waste polymer have been identified and are investigated through experiment. The use of ultra-fine particle or homogeneous catalysts and liquid superacids aims to overcome the inherent diffusional limitations encountered in a polymer melt penetrating a solid catalyst by exploiting the intrinsic void volume of the polymer. However, traditional polymer-catalyst contacting patterns have the advantage of allowing the polymers to be processed in existing processing units. Therefore, relevant design parameters of heterogeneous catalysts, i.e., acidity//basicity and structure, are examined. The experimental work is complemented by a theoretical study aimed at a priori prediction of the degradation characteristics of a given polymer feedstock and catalyst formulation. The database amassed from experimental studies provides general qualitative rules that serve as a starting point for formulating a predictive, quantitative mechanistic model. In general, the tendency of a polymer toward particular degradation products has been attributed to three factors: ( 1) strength of bonds in the polymer backbone, (2) presence of tertiary hydrogens, and(3) relative strength of substituent bonds. Each of these qualitative rules is examined quantitatively using an approach combining mechanistic modeling and computational quantum chemistry. Preliminary work has already been carried out to demonstrate the application of mechanistic modeling to quantify the tendency of different polymers to degrade thermally to monomer. An education plan linking research and teaching has been formulated to teach chemical engineering students to deal with complex issues in a changing and increasingly entrepreneurial environment. The core components which comprise this plan are (1) development of generic manufacturing modules linking theoretical concepts to real world processes, (2) introduction of computational quantum chemistry into the undergraduate curriculum for property estimation, and (3) development of communication skills through individual and team oral and written presentations. Each of these is a generic component that can be incorporated throughout the curriculum.