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Document Type

Dissertation - University Access Only

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Agricultural and Biosystems Engineering

First Advisor

James L. Julson


This dissertation investigated the microwave-assisted pyrolysis of several biomass feedstocks to produce bio-oils and catalytic upgraded these bio-oils into hydrocarbons with various zeolite catalysts. In the evaluation and optimization of the microwave-assisted pyrolysis, three biomass feedstocks were examined: switchgrass (SG), prairie cordgrass (PCG) and Ponderosa pine wood (PPW). Response surface methodology (RSM) was used for optimizations of the production of pyrolysis products. Optimal conditions for bio-oil yields from SG, PCG and PPW were found at the same condition: reaction temperature of 650 °C and residence time of 18 min. The maximum bio-oil yields of the three biomass feedstocks were 36.3%, 33.1% and 45.6%, respectively. The effectiveness of reaction temperature, residence time, and particle size on the yield of bio-oil and volatiles was evaluated. Prediction models were satisfactorily developed to describe the bio-oil conversion yield as a function of reaction temperature and time for SG, PCG and PPW. Results showed that both reaction temperature and residence time were significant factors affecting the production of bio-oils whereas the particle size was found to be insignificant on the microwave-assisted pyrolysis of switchgrass for bio-oil production. GC-MS analysis indicated that the bio-oil produced from various biomass feedstocks contained a series of important and useful chemical compounds: phenols, aliphatic hydrocarbons, aromatic hydrocarbons, and furan derivatives. The effectiveness of HZSM-5 and HS-Mix as zeolite thermal cracking catalysts for the production of hydrocarbons from raw bio-oils was investigated. HS-mix catalysts were produced by physically mixing HZSM-5 with silica-alumina with different HZSM-5/silica-alumina ratios and then characterized. Upgraded bio-oils were analyzed and characterized by composition analysis (using GC-MS), pH analysis, water content, viscosity, density and elemental analysis. The results of GC-MS tests showed that most components in the upgraded bio-oils were hydrocarbons mainly composed of 1,2-dimethyl-Benzene, p-Xylene, 1,2,3-trimethyl-Benzene, 1,2,4- trimethyl-Benzene, 1,3-butadienly-Benzene, 1-ethylidene-1H-Indene, and 1-methyl- Naphthalene. After zeolite cracking, the water content, viscosity and density of bio-oils decreased whereas the pH value increased. Elemental analysis indicated all the oxygen content levels of the bio-oils derived from pyrolysis of SG, PCG, and PPW decreased after zeolite catalytic cracking. Energy balance revealed that the energy recovery efficiencies were reasonable (45.1%-52.8%).

Library of Congress Subject Headings

Biomass energy
Biomass conversion
Plant biomass
Ponderosa pine


Includes bibliographic references (pages 152-166)



Number of Pages



South Dakota State University


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