03/25/2024
By Danielle Fretwell

The Francis College of Engineering, Department of Chemical Engineering, invites you to attend a Doctoral Dissertation defense by Fuat Sakirler on: "Effects of Noncovalent Interactions on the Chemical Kinetics of Biomass Fast Pyrolysis Chemistry."

Candidate Name: Fuat Sakirler
Degree: Doctoral
Defense Date: Thursday, April 4, 2024
Time: 1 to 3 p.m.
Location: Perry 215

Committee:

  • Advisor: Hsi-Wu Wong, Ph.D., Associate Professor, Department of Chemical Engineering, UMass Lowell
  • Fanglin Che, Ph.D., Assistant Professor, Department of Chemical Engineering, UMass Lowell
  • Lawrence M. Wolf, Ph.D., Assistant Professor, Department of Chemical Engineering, UMass Lowell
  • Richard H. West, Ph.D., Associate Professor, Department of Chemical Engineering, Northeastern University

Brief Abstract:

Production of biofuels and renewable chemicals from biomass is projected to grow in the coming decades with increased global concerns over energy shortage and negative environmental impacts caused by ever-increasing fossil fuel consumption. Fast pyrolysis is a promising, cost-effective thermochemical method for biomass conversion. However, its product distribution is inherently non-selective due to its complex compositions, entangled reaction pathways, and multiphasic nature under pyrolysis conditions, posing significant commercialization challenges. Understanding the chemical kinetic and transport phenomena at the molecular-level of biomass fast pyrolysis could be key to overcoming this challenge. The primary aim of this dissertation is to advance the underlying chemistry of biomass fast pyrolysis.

In this dissertation, a new intramolecular hydroxyl-activated mechanism is first presented for cellulose activation The DFT-calculated activation energies for cellulose activation and depolymerization incorporating noncovalent interactions were found to be 50.8 kcal mol-1 and 40.9 kcal mol-1, respectively. Next, molecular-level understanding of NCIs between cellulose and lignin under fast pyrolysis conditions was investigated using combined theoretical and experimental approach. The catalytic and inhibitory effects of lignin structures on the formation pathways of cellulose-derived three major products (viz. levoglucosan, glycolaldehyde, and 5-hydroxymethylfurfural) were revealed using DFT calculations. The NCIs during co-pyrolysis of cellulose with hydrogen-rich thermoplastics (viz. polyethylene, polystyrene, polyethylene glycol, and polyketone) were studied next. DFT calculations unraveled catalytic and inhibitory effects on the formation pathways of cellulose-derived three major products caused by functional groups (viz. aromatic, ether, or ketone groups) of molten plastics. Finally, depolymerization pathways during fast pyrolysis of chitin and chitosan were investigated. The effect of nitrogen-containing side groups on glycosidic bond cleavage and ring opening reaction and the roles of NCIs is explored.

The molecular-level understanding of NCIs on degradation mechanisms of biomass fast pyrolysis presented in this dissertation could guide process design, catalysis research and kinetic modeling efforts. Insights gained from the effect of NCIs on the reaction pathways of fast pyrolysis of various biopolymers establish the framework for studying the effect of interactions among other polymers with more complex structures in the future. The discovery of effects of NCIs induced by functional groups offers opportunities for tunable fast pyrolysis.