Date of Award

9-2010

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Chemical Engineering

First Advisor

George W. Huber

Second Advisor

W. Curt Conner

Third Advisor

Scott M. Auerbach

Subject Categories

Chemical Engineering

Abstract

Due to its low cost and large availability lignocellulosic biomass is being studied worldwide as a feedstock for renewable liquid biofuels. Currently there are several routes being studied to convert solid biomass to a liquid fuel, which involve multiple steps at long residence times thus greatly increasing the cost of biomass processing. Catalytic fast pyrolysis (CFP) is a new promising technology to convert directly solid biomass to gasoline-range aromatics that fit into the current infrastructure. CFP involves the rapid heating of biomass (~500˚C sec-1) in an inert atmosphere to intermediate temperatures (400 to 600 ˚C) in the presence of zeolite catalysts. During CFP, biomass is converted in a single step to produce gasoline-range aromatics which are compatible with the gasoline of the current market. CFP has many advantages over other conversion processes including short residence times (2-10 s) and inexpensive catalysts. The major impediment to the further development of CFP is the lack of fundamental understanding of the underlying chemistry of the process. The first goal of this thesis is to study the underlying chemistry of the CFP process using model compounds in a small pyroprobe micro reactor. For this part of the study the homogeneous thermal decomposition routes of glucose were identified along with the key intermediates. Through isotopic labeling studies the heterogeneous C-C bond forming reactions were determined. Lastly, the relative rates of the homogeneous and heterogeneous reactions were estimated. Since CFP in the small pyroprobe reactor is not scalable the second part of the study focused on designing and building a bench scale fluidized bed reactor to demonstrate CFP on a larger scale. This fluidized bed reactor was used to optimize the CFP of pine wood with ZSM-5 catalyst. The effect of reaction conditions such as temperature and biomass space velocity on the aromatic yield and selectivity was determined. The long term stability of the catalyst was also studied.

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