Degree Type

Dissertation

Date of Award

2016

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Major

Mechanical Engineering

First Advisor

Robert C. Brown

Abstract

Catalytic pyrolysis of biomass has been identified as one of the pathways to replace fossil fuel resources for transportation fuels and mitigate environmental impacts of fossil fuels. However, lack of technical and economic information on this technology has created uncertainty about the feasibility of this approach to biofuels. This dissertation helps to fill some of the gaps and advances of catalytic pyrolysis as an alternative approach to producing advanced biofuels.

First, techno-economics of a woody biomass, mild catalytic pyrolysis pathway for transportation fuels was investigated. This study detailed the process modelling, energy analysis, economic analysis and uncertainty analysis of this technology. Novel methods for heat exchanger network design, higher heating value (HHV) based energy analysis and uncertainty analysis was demonstrated in this study.

Second, techno-economics of microalgae catalytic pyrolysis to transportation fuels was analyzed mainly to investigate the influence of moisture in feedstock and energy integration of the process. This study provides details of different dewatering techniques and illustrates how process heat can be used to partially dewater feed algae. Moreover, low product yield was identified as the major contributor for high fuel selling price obtained for this pathway.

Lastly, as it is important to understand the reaction chemistries of lignocellulosic biomass conversion over zeolites, lignin and cellulose conversion during catalytic pyrolysis was analyzed in micro-scale reactor setup, where mass and heat transfer effects are negligible. Lignin model compound study performed using phenol and anisole showed that phenolic functionalities play a major role in the formation of aromatics and coke over zeolites. Hydroxyl functionality promoted coke formation, while methoxy functionality contributed toward alkylating aromatics and reducing coke. From the cellulose study, it was found that acid sites on the external surface of zeolites plays a major role in coke formation due to lower spatial restriction and dehydrogenation compared to acid sites in the internal pores of zeolites. Impregnating acid into cellulose and pyrolyzing it over silylated zeolites was demonstrated as a combined homogeneous and heterogeneous acid-catalyzed pathway that significantly improved aromatic yield.

Copyright Owner

Chamila Rajeeva Thilakaratne

Language

en

File Format

application/pdf

File Size

115 pages

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