The Forest Products Association of Canada (FPAC) recently concluded that pulp, paper, and saw mills could co-produce new, high value bioenergy, biochemicals, and biomaterials with current outputs. Based on this report, they challenged companies, governments and other partners to generate an additional $20 billion in economic activity from new innovations and markets by 2020. The goal of my research is to make large-scale biorefineries a reality by examining and harnessing the fundamental kinetic and transport phenomena of fractionation and catalysis for maximum economic and environmental benefit.
The first step in the production of chemicals and fuels from cellulosic biomass is to produce reactive intermediates. If this initial fractionation is done poorly, the efficiency of all the downstream processes decreases; if it is done well then all the downstream processes are made easier. Hydrothermal or water-only hydrolysis removes hemicellulose, extractives and some lignin from biomass, has reduced capital and operating costs compared to other strategies but the costs are still too high for commercial implementation. More work is needed.
Flowthrough Pretreatment of Softwoods: Fundamentals and Applications
Many pretreatment strategies rely on batch reactors, however fixed bed flowthrough reactors have also been shown to remove significant amounts of lignin and hemicellulose and produce readily convertible solids from corn stover, poplar, and switchgrass. But little work has been done using regionally important feedstocks such softwoods. By applying this unique reactor system to softwoods, detailed product profiles of softwood deconstruction will be developed in order to build kinetic models as well as heat and mass transfer models that will lead to new pretreatment strategies.
As pretreatment products are identified in the solution, possible purification operations will be explored in order to determine the possibility of separating carbohydrate fragments from lignin fragments. The separation of these chemicals would create further opportunities for value added end products.
Recovery and Purification of Extractives
Many types of forestry biomass contain signature extractives, soluble compounds with potential uses as nutraceuticals and pharmaceuticals. Western red cedar, B.C.’s provincial tree, contains beta-thujaplicin which has antimicrobial and anti-tumour properties. My group seeks to generate a process for the extraction and purification of this high-value extractive.
Chemocatalytic Conversion of Biomass
An emerging biomass processing paradigm is hydrogenolysis in which biomass is subjected to hydrolysis in the presence of a metal catalyst with a hydrogen vapor space. As sugar monomers are released from the biomass they are instantaneously hydrogenated on the metal catalyst to produce sorbitols which can be further processed into fuels or polymers such as polyester. Most work to date has been done with idealized substrates such microcrystalline cellulose. The work to date is promising but real biomass is a complex material with hundreds of compounds that could interfere with the desired reactions. Hydrogenolysis with native biomass requires further study. The process is a complex one involving reactants in all three phases as well as two different catalysts. Mass transfer and kinetic models are needed as well as process analyses to identify the aspects in critical need of improvement.
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2. Liu CG, Wyman CE. Partial flow of compressed-hot water through corn stover to enhance hemicellulose sugar recovery and enzymatic digestibility of cellulose. Bioresour. Technol. 2005; 96: 1978-1985
3. McKenzie HL, Wyman CE. “Comparison of Xylan Removal from Poplar and Model Substrates During Hydrothermal Pretreatment.” In preparation.
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- Kapu NS, Trajano HL§. “Hemicellulose hydrolysis in recalcitrant feedstocks: softwoods and bamboo.” Invited review for Biofuels, Bioproducts, and Biorefining. Accepted July 2014.
- Rosales Calderon O, Trajano HL§, Duff SJB. “Stability of cellulase and β-glucosidase under hydrolysis conditions,” PeerJ 2:e402. http://dx.doi.org/10.7717/peerj.402.
- Trajano HL, Engle NL, Foston M, Ragauskas AJ, Tschaplinski TJ, Wyman CE§. 2013. “Fate of lignin during hydrothermal pretreatment,” Biotechnology for Biofuels 6. DOI: 10.1186/1754-6834-6-11
- Trajano HL, DeMartini JD, Studer MH, Wyman CE§. 2013. “Comparison of the effectiveness of a fluidized sand bath and a steam chamber for reactor heating,” Industrial and Engineering Chemistry Research, 52: 4932-4938.
- Podkaminer KP, Guss AM, Trajano HL, Hogsett D, Lynd L§. 2012. “Characterization of xylan utilization and discovery of a new endoxylanase in Thermoanaerobacterium saccharolyticum through targeted gene deletions,” Applied and Environmental Microbiology, 78: 8441-8447.
- Studer MH, Brethauer S, DeMartini JD, McKenzie HL, Wyman CE§. 2011. “Co-hydrolysis of dilute pretreated Populus slurries to support development of a high throughput pretreatment system,” Biotechnology for Biofuels, 4: 19-29.
- Studer MH, DeMartini JD, Brethauer S, McKenzie HL, Wyman CE§. 2010. “Engineering of a high-throughput screening system to identify cellulosic biomass, pretreatments, and enzyme formulations that enhance sugar release,” Biotechnology and Bioengineering 105: 231-238.
- Rosales Calderon O, Trajano H, Posarac D, Duff S. “Economic evaluation of the re-adsorption of hydrolytic enzymes onto fresh substrate after enzymatic hydrolysis of pre-treated wheat straw,” Pacific Rim: Summit on Industrial Biotechnology and Bioenergy, Vancouver, Canada, October 2012.
- Rosales Calderon O, Trajano H, Posarac D, Duff S. “Process simulation and economic evaluation for bioethanol production implementing the enzyme recycling by readsorption,” 62nd Canadian Chemical Engineering Conference, Vancouver, BC, October 2012.
- Trajano HL, Pattathil S, Tomkins BA, Hahn MG, Tomkins BA, Tschaplinski TJ, van Berkel GJ, Wyman CE, “Characterization of cell wall structure on the removal of hemicellulose from Populus during flowthrough pretreatment,” 62nd Canadian Chemical Engineering Conference, Vancouver, BC, October 2012.
- McKenzie HL, Emory JF, Engle NL, Foston MB, Ragauskas A, Tomkins BA, Tschaplinski TJ, van Berkel GJ, Wyman CE, “Solubilization of lignin and hemicellulose during hydrothermal pretreatment,” 61st Canadian Chemical Engineering Conference, London, ON, October 2011.
- McKenzie HL, Engle NL, Foston MB, Ragauskas A, Tschaplinski T, Wyman CE, “Characterization of lignin after water-only pretreatment,” 33rd Symposium on Biotechnology for Fuels and Chemicals, Seattle, WA, May 2011.
- McKenzie HL, DeMartini JD, Studer M, Wyman CE, “Understanding the effects of reactor design on biomass sugar recovery,” World Congress of Chemical Engineering, Montreal, Quebec, Canada, August 2009.
Conference Presentations, Poster
- Rosales Calderon O, Trajano HL, Posarac D, Duff S, “Modeling of enzymatic hydrolysis of pretreated wheat straw as a function of hydrolysis time, enzyme concentration, and lignin concentration,” 36th Symposium on Biotechnology for Fuels and Chemicals, Clearwater Beach, FL, May 2014.
- Rosales Calderon O, Trajano HL, Posarac D, Duff S, “Technical and economic evaluation of enzyme recycle by re-adsorption for bioethanol production,” 35th Symposium on Biotechnology for Fuels and Chemicals, Portland, OR, May 2013.
- McKenzie HL, Engle NL, Emory JF, Tomkins BA, Tschaplinski TJ, Van Berkel GJ, Wyman CE, “Water-only flowthrough pretreatment of poplar and birchwood xylan at 180oC”, 32nd Symposium on Biotechnology for Fuels and Chemicals, Clearwater Beach, FL, May 2010.
- McKenzie HL, DeMartini JD, Studer M, Wyman CE, “Understanding the effects of reactor design on glucose and xylose recovery from pretreatment and enzymatic hydrolysis,” 31st Symposium on Biotechnology for Fuels and Chemicals, San Francisco, CA, May 2009.
- Studer M, DeMartini JD, McKenzie HL, Wyman CE. “Integrated high throughput pretreatment and enzymatic hydrolysis in 96 well plates,” 58th Canadian Chemical Engineering Conference, Ottawa, ON, Canada, October 2008.
- Studer MH, DeMartini JD, McKenzie HL, Wyman CE, “Development of high throughput pretreatment systems for cellulosic biomass,” 30th Symposium on Biotechnology for Fuels and Chemicals, New Orleans, LA, May 2008.