Degree Type

Dissertation

Date of Award

2014

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

First Advisor

Robert Brown

Abstract

Current biorefineries utilize only sugars or lipids in biomass for fuel production, leaving protein-rich residues underutilized. Improper disposal of those residues may cause economical or ecological problem. Research in this dissertation focuses on developing pyrolysis/catalytic pyrolysis as a pathway for producing biofuel or bio-based chemical from protein- and lipid- rich biomass.

Fast pyrolysis of microalgae remnants after lipid extraction produced bio-oil with around 13% nitrogen content. This large amount of nitrogen can have deleterious effects on catalysts during bio-oil upgrading. Catalytic pyrolysis of protein-rich algal biomass with HZSM-5 catalyst yielded aromatic and olefinic hydrocarbons. Most of nitrogen in biomass was released as ammonia, which suggests feasibility for recycling nitrogen as a nutrient for microalgae cultivation.

Catalytic pyrolysis of protein-rich biomass produced significantly higher yields of hydrocarbons compared with lignocellulosic biomass. Protein and lipid produced higher yield of hydrocarbons compared with carbohydrates and lignin in biomass. The lipid components in biomass have positive synergistic effect to enhance yields of aromatics. The effect of reactor configuration on the products of catalytic pyrolysis was also investigated. In-situ catalytic pyrolysis produced significantly more aromatics and less olefins compared with ex-situ catalytic pyrolysis. Selectivity of monocyclic aromatics such as benzene and toluene for ex-situ catalytic pyrolysis was higher than for the in-situ method. Variance of hydrocarbon yields for in-situ and ex-situ catalytic pyrolysis were explained by differences in gas flow and heat transfer for the two kinds of catalytic pyrolysis. The remarkably high olefin yield from ex-situ catalytic pyrolysis suggests the possibility of exploiting the process to preferentially obtain olefins from biomass.

Techno-economic analysis was performed on an integrated biorefinery combining corn ethanol production and catalytic pyrolysis of dried distillers grains with solubles (DDGS) for hydrocarbon production. In addition to ethanol, a wide range of hydrocarbons including aromatics, olefins, and synthetic gasoline and diesel are produced from the integrated facility. The hydrocarbon products command a substantially higher market value than could be realized by selling the unprocessed DDGS. However, the capital costs and operating costs for the integrated biorefinery are higher than the conventional stand-alone corn ethanol biorefinery. The minimum fuel selling price (MFSP) for the integrated scenario is comparable to the MFSP for the stand-alone scenario. Combined with the benefit of product diversity, the proposed integrated corn biorefinery may be competitive with conventional stand-alone ethanol production.

Copyright Owner

Kaige Wang

Language

en

File Format

application/pdf

File Size

160 pages

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