05/31/2024
By Danielle Fretwell

The Francis College of Engineering, Department of Chemical Engineering, invites you to attend a Doctoral Dissertation Proposal defense by Mihriye Doga Tekbasb on: "Revealing the Role of Mass Transfer and Chemical Kinetics Interplay in Macromolecule Pyrolysis."

Candidate Name: Mihriye Doga Tekbas
Degree: Doctoral
Defense Date: Monday, June 10, 2024
Time: 9:30 and 11 a.m.
Location: Perry Hall 415

Committee:

  • Advisor: Hsi-Wu Wong, Associate Professor, Chemical Engineering, University of Massachusetts Lowell
  • Wei Fan, Professor, Chemical Engineering, University of Massachusetts Amherst
  • Dongming Xie, Associate Professor, University of Massachusetts Lowell
  • Wan-Ting (Grace) Chen, Assistant Professor, University of Massachusetts Lowell

Brief Abstract:
This dissertation investigates the interplay between mass transfer and chemical kinetics during the pyrolysis of waste macromolecules, specifically focusing on high-density polyethylene (HDPE) and cellulose. Pyrolysis, a thermochemical decomposition process performed in the absence of oxygen, is essential for converting organic materials into energy sources such as liquid oil, syngas, and char. Three macromolecule pyrolysis reaction systems are explored. First, the influence of a second macromolecule (e.g., molten plastics or lignin) on cellulose fast pyrolysis is studied. Our findings indicate that the escape (e.g., evaporation or thermal injection) of large cellulose-derived pyrolysis products is inhibited by the presence of another phase, thereby promoting their further decomposition. Additionally, the functional groups contained in this molten second phase induce non covalent interactions, leading to catalytic or inhibitory effects that alter the reaction pathways of cellulose fast pyrolysis. Second, the competition between the evaporation of HDPE-derived pyrolysis products and their further decomposition is studied. Our results reveal that the reaction pressure can be used to control this competition, and the dimensionless Damköhler number can be used to characterize which one of the two processes is limiting. Third, catalytic HDPE pyrolysis using various zeolites is investigated, particularly focusing on the performance of a novel aluminosilicate zeolite, referred to as ZEO-1, which features intersecting three-dimensional pores of varying sizes with a high surface area and thermal stability of up to 1000 °C. The hypothesis that product distributions from HDPE pyrolysis can be tuned by system pressure and zeolite pore size is tested. The findings from this dissertation result in new fundamental understanding of chemical reaction engineering principles governing macromolecule pyrolysis, critical to future scale-up and commercialization of these processes. The study also contributes to in the broader field of sustainability and circular economy by suggesting ways to optimize pyrolysis technologies for improved utilization of biomass and plastics waste.