Improved ethanol yield and reduced Minimum Ethanol Selling Price (MESP) by modifying low severity dilute acid pretreatment with deacetylation and mechanical refining: 1) Experimental

Biotechnology for Biofuels

Xiaowen Chen²  Ling Tao²  Joseph Shekiro²  Ali Mohaghaghi²  Steve Decker³  Wei Wang³  Holly Smith²  Sunkyu Park¹  Michael E Himmel³  Melvin Tucker² 

[1] Department of Forest Biomaterials, North Carolina State University, 2820 Faucette Drive, Raleigh, NC, 27695, USA

[2] National Bioenergy Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO, 80127, USA

[3] Bioscience Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO, 80127, USA

关键词: PFI mill;    Mechanical refining;    Deacetylation;    Fermentation;    Enzymatic hydrolysis;    Pretreatment;    Bioethanol;   

Others  :  798239
DOI  :  10.1186/1754-6834-5-60

 received in 2012-06-22, accepted in 2012-08-07,  发布年份 2012

【 摘 要 】

Background

Historically, acid pretreatment technology for the production of bio-ethanol from corn stover has required severe conditions to overcome biomass recalcitrance. However, the high usage of acid and steam at severe pretreatment conditions hinders the economic feasibility of the ethanol production from biomass. In addition, the amount of acetate and furfural produced during harsh pretreatment is in the range that strongly inhibits cell growth and impedes ethanol fermentation. The current work addresses these issues through pretreatment with lower acid concentrations and temperatures incorporated with deacetylation and mechanical refining.

Results

The results showed that deacetylation with 0.1 M NaOH before acid pretreatment improved the monomeric xylose yield in pretreatment by up to 20% while keeping the furfural yield under 2%. Deacetylation also improved the glucose yield by 10% and the xylose yield by 20% during low solids enzymatic hydrolysis. Mechanical refining using a PFI mill further improved sugar yields during both low- and high-solids enzymatic hydrolysis. Mechanical refining also allowed enzyme loadings to be reduced while maintaining high yields. Deacetylation and mechanical refining are shown to assist in achieving 90% cellulose yield in high-solids (20%) enzymatic hydrolysis. When fermentations were performed under pH control to evaluate the effect of deacetylation and mechanical refining on the ethanol yields, glucose and xylose utilizations over 90% and ethanol yields over 90% were achieved. Overall ethanol yields were calculated based on experimental results for the base case and modified cases. One modified case that integrated deacetylation, mechanical refining, and washing was estimated to produce 88 gallons of ethanol per ton of biomass.

Conclusion

The current work developed a novel bio-ethanol process that features pretreatment with lower acid concentrations and temperatures incorporated with deacetylation and mechanical refining. The new process shows improved overall ethanol yields compared to traditional dilute acid pretreatment. The experimental results from this work support the techno-economic analysis and calculation of Minimum Ethanol Selling Price (MESP) detailed in our companion paper.

【 授权许可】

   
2012 Chen et al.; licensee BioMed Central Ltd.

【 图 表 】

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