Product Distribution from Fast Pyrolysis of Biomass
Biomass is the only sustainable source of organic carbon and has been recognized as an attractive feedstock for fuels and chemicals production. Fast pyrolysis is a promising method to transform solid biomass into a liquid product called as ‘bio-oil’. Analogous to crude oil, bio-oil can also be processed in a currently existing petroleum refinery infrastructure to produce an array of useful products. The commercial success of different technologies related to bio-oil processing demands knowledge of its chemical composition and ways to alter it.
Bio-oil contains many different chemical species that can be classified into a) low molecular weight species (eg. Formic acid, glycolaldehyde, acetol); b) Furans (eg. Furfural, hydroxy methyl furfural); c) Phenols (eg. Methyl phenol, methoxy phenol) and d) Anhydrose sugars (eg. Levoglucosan). Depending on the strategy used to process bio-oil and the end product of interest, certain components of bio-oil may be desirable. For example, steam reforming of bio-oil to generate hydrogen, more low molecular weight compounds are preferred.
The bio-oil chemical speciation eventually depends upon the biomass composition (its hemicellulose, cellulose, lignin and mineral matter content) and processing conditions (temperature, residence time of pyrolysis vapors). Abundant literature is available focusing on optimizing the bio-oil yield, however little attention was provided to the quality of the bio-oil produced. Chemical phenomena referred as primary and secondary reactions have been traditionally avoided when modeling the pyrolysis process. With the increasing interest in usage and upgrading of bio-oil, it is imperative to understand the effect of feedstock chemistry and process parameters and accurately predict the yields of species present in bio-oil.
- Figure 1. Species resulting from the pyrolysis of cornstover at 500oC
- Figure 2. Micropyrolyzer-GC-MS system at CSET
We, at CSET, are using a micro-pyrolyzer, which is directly connected to a GCMS, to establish the relationships between chemical structures of lignocellulosic constituents of biomass and process parameters to the resulting product distribution based on the primary reactions. Various biomass materials and chemical compounds chosen as model compounds to mimic biomass components are pyrolyzed. The fast pyrolysis vapor product stream is sent directly to a GC/MS to have its composition analyzed. Additional complexities accounting for secondary reactions and reactor configuration are also being studied with the help of 100g/hr bench scale fluidized bed reactor.
Interested to know more about this research?
contact Pushkaraj Patwardhan, Iowa State University, prp
iastate.edu
For inquiries related to the biorenewables research program at Iowa State, please contact:
Dr. Robert C. Brown, Iowa State University, rcbrowniastate.edu
Dr. Justinus A. Satrio, Iowa State University, jasatrioiastate.edu
Iowa State University CSET, 0411 Marston Hall, Ames, Iowa 50011-2153
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