Controlling biomass properties for optimizing fast pyrolysis products

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Jeffrey, Brandon
Iowa State University
brown midrib; cell wall; lignin; maize; pyrolysis; QTL
thesis / dissertation description
The energy future of the United States is likely to include a large number of traditional and alternative energy sources and technologies. Fast pyrolysis has been identified as one of the alternative energy conversion processes that could play a role in this energy future. Fast pyrolysis produces solid (biochar), liquid (bio-oil), and gaseous products (syngas). Bio-oil is the main component (up to 80%) and has a number of potentially useful applications. Bio-oil composition is complex and is related to cell wall composition, as compounds in the bio-oil derive from the individual cell wall components cellulose, hemicelluloses, and lignin.While a variety of different pyrolysis reactor technologies and biomass types have been explored, relatively little attention has been paid to the amount of variation within a single type of biomass. The goals of this research were to compare distribution of bio-oil compounds for maize cobs and stover, determine if there is significant variation for bio-oil compounds among different maize genotypes, identify quantitative trait loci (QTL) for bio-oil compounds, and discuss the implications of results for breeding dual purpose maize. To address these questions, we used pyrolysis/gas-chromatography-mass spectrometry (Py/GC-MS) to convert maize stover and cobs to bio-oil (Py), and separate (GC), detect and measure (MS) bio-oil compounds. Py-GC-MS allows a high sample throughput (20/day) required for disciplines such as plant breeding. Variation for 26 bio-oil compounds is explored in maize cobs and stover amongst five near isogenic hybrids with four hybrids each carrying one brown midrib mutation (bm1-bm4) (Chapter 3). A more diverse set of 10 maize hybrids is used to further explore this variation (Chapter 5). Quantitative trait loci (QTL) are identified in the intermated B73 x Mo17 (IBM) Syn4 population for ten bio-oil compounds and compared to the QTL literature for other cell wall related traits (Chapter 4). A discussion for the implications of our finding in regards to breeding implications for dual purpose maize is also included in Chapter 4. It is very likely that bio-oil quality and yield can be improved via plant breeding, which would help contribute to making bio-oil production and use more economically appealing.