Degree Type

Dissertation

Date of Award

2017

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Major

Mechanical Engineering; Biorenewable Resources and Technology

First Advisor

Robert C. Brown

Abstract

The pyrolysis of cellulose to form levoglucosan is investigated in this study. Although the stoichiometric yield of levoglucosan from the pyrolysis of cellulose is expected to be 100%, only about 60 wt.% yields are reported in the literature.[1–3] Several possible reasons for this limitation are investigated through experiments in micropyrolyzers and computational studies on the depolymerization of cellulose. Heat and mass transfer limitations in an experimental apparatus is one possible limitation on the yield of levoglucosan. Repolymerization of condensed phase reaction intermediates could prevent the formation and release of volatile levoglucosan. Thermohydrolysis of pyrolyzing cellulose to form non-volatile and thermally unstable glucose has also been proposed as a mechanism that reduces levoglucosan yields. Secondary reactions in the gas phase were also investigated to explain limitations on levoglucosan yields. Population balance models were developed to test ideas on how cellulose depolymerized to form levoglucosan at less than stoichiometric yields. These models were supported with chemical kinetic data obtained from transient pyrolysis experiments.

Under carefully controlled experimental conditions, no evidence was found for heat and mass transfer effects limiting levoglucosan yields to 60 wt.% nor do secondary reactions in the condensed- or gas-phases appear to offer a satisfactory explanation. Based on modeling results, it appears levoglucosan-forming reaction rates that decrease as oligosaccharide chain length decreases is the most plausible explanation for limitations on levoglucosan yield from cellulose.

DOI

https://doi.org/10.31274/etd-180810-5222

Copyright Owner

Juan Sebastian Proano-Aviles

Language

en

File Format

application/pdf

File Size

116 pages

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