Project Number: 8072-41000-111-00-D
Project Type: In-House Appropriated
Start Date: Sep 22, 2020
End Date: Sep 21, 2025
Objective 1 Develop integrated processes to enable commercial production of value-added products in existing corn ethanol biorefineries. This includes co-conversion of biomass (corn stover, corn fibers) with corn starch for production of value-added products to enhance biorefinery profitability and stability. Sub-objective 1-A. Develop technologies that enable the integrated processing of pretreated biomass with grains at existing biofuels production facilities for cellulosic ethanol production. Sub-objective 1-B. Utilize advanced enzymatic fractionation processes to separate fiber and starch prior to fermentation to generate a fiber rich streams for pretreatment and biomass sugar production studies. Sub-objective 1-C. Produce and utilize sugars from biomass/grain mixtures for the fermentation of value-added coproducts. Objective 2 Develop self-sustained biomass pretreatment and conversion processes to enable commercial production of fermentable sugars and lignin-derived products. This includes but is not limited to the use of Na2CO3, which can be generated by NaOH absorption of CO2, a co-product of aerobic/anaerobic fermentation, for biomass pretreatment. Both lignin fractions obtained prior to pretreatment and after sugar extraction will be investigated as feedstocks for conversion to high-value products or fuels. Sub-objective 2-A. Develop a process for pretreatment of biomass using the Na2CO3 solutions made by absorption of CO2 from ethanol and 2,3-butanediol (2,3-BDO) fermentations in NaOH. Sub-objective 2-B. Develop a process using the Na2CO3-pretreated biomass as feedstocks for production of fermentable sugar solutions suitable for use as substrates in industrial fermentations. Sub-objective 2-C. Develop lignin recovery and conversion processes that generate advanced biofuels, high-value chemicals, or renewable materials. Objective 3 Develop hybrid biocatalytic/chemical processing technologies to enable the commercial conversion of lignocellulosic sugars to advance biofuels or chemicals. Fermentable sugars from biomass feedstocks will be utilized to produce a microbial source of 2,3-BDO. The recovered 2,3-BDO will then be investigated by downstream chemical upgrading technologies to produce advance biofuels or high-value chemicals. Sub-objective 3-A. Develop fermentation processes for the production and recovery of 2,3-butanediol. Sub-objective 3-B. Develop chemical conversion process to upgrade 2,3-butanediol to an advanced biofuel.
The first objective will establish technologies that integrate sugars derived from biomass feedstocks that are not directly connected to corn grains (e.g. corn stover and switchgrass) with corn starch-derived sugars for the production of ethanol and/or industrial chemicals. Pretreated biomass will be co-converted with corn or other starch-containing feedstocks for production of cellulosic ethanol within existing biorefineries. The primary focus will investigate additional ethanol production in dry-grind corn facilities. Other investigations will be made into process technologies whereby the fiber isolated from corn kernels prior to ethanol fermentation can be utilized in conjunction with other pretreated biomass to produce additional fermentable sugars. The fermentable sugars will then be utilized in fermentation processes for production of value-added co-products, such as the carotenoid astaxanthin, in existing ethanol biorefineries. The second objective will develop a self-sustainable pretreatment process for corn stover and switchgrass using sodium carbonate solutions generated by the absorption of carbon dioxide produced from simulated industrial fermentations. This pretreatment process will be optimized in order to maintain at least 85% of the orginal cellulose and at least 70% of the original hemicellulose in corn stover and switchgrass. Following sodium carbonate pretreatment the pretreated biomass will be hydrolyzed to generate fermentable sugars using commercially available enzymes. The enzymatic hydrolysis process will be optimized to maintain at least 50 g/L of total sugars in the hydrolysate and greater than 75% theoretical sugar yields. The residual insoluble solids obtained after pretreatment or enzymatic hydrolysis will also be utilized to develop a process for lignin recovery. The recovered lignin will be utilized as a separate feedstock for the generation of advanced biofuels via biochemical conversion, or in material applications for preparing biobased epoxy resins. The third objective will investigate fermentation processes for the production of 2,3-butanediol (2,3-BDO) from fermentable sugars of pretreated corn stover or switchgrass. The 2,3-BDO produced by fermentation will be catalytically upgraded to an advanced biofuel. Fermentation processes will be developed and optimized to generate 2,3-BDO at high titers and yields. Additional process development will focus on separation and recovery processes following fermentation in order to obtain a high purity yield of 2,3-BDO for downstream chemical upgrading. The recovered 2,3-BDO will then be upgraded via a multi-step chemical conversion route utilizing dehydration, aldol condensation, and hydrodeoxygenation to generate a hydrocarbon fuel. Both chemical catalyst selection will be identified and process parameters optimized as the upgrading process is investigated.