Integrated experimental and technoeconomic evaluation of two-stage Cu-catalyzed alkaline-oxidative pretreatment of hybrid poplar

Aditya Bhalla; Peyman Fasahati; Chrislyn A Particka; Aline E Assad; Ryan J Stoklosa; Namita Bansal; Rachel Semaan; Christopher M Saffron; David B Hodge; Eric L Hegg

doi:10.1186/s13068-018-1124-x

Integrated experimental and technoeconomic evaluation of two-stage Cu-catalyzed alkaline-oxidative pretreatment of hybrid poplar

Biotechnol Biofuels. 2018 May 17:11:143. doi: 10.1186/s13068-018-1124-x. eCollection 2018.

Authors

Aditya Bhalla^{1

2}, Peyman Fasahati^{1

3

4}, Chrislyn A Particka¹, Aline E Assad^{1

5}, Ryan J Stoklosa^{1

6

7}, Namita Bansal^{1

2}, Rachel Semaan², Christopher M Saffron^{1

3

6}, David B Hodge^{1

3

6

8

9}, Eric L Hegg^{1

2}

Affiliations

¹ 1DOE Great Lakes Bioenergy Research Center, Michigan State University, 1129 Farm Lane, East Lansing, MI 48824 USA.
² 2Department of Biochemistry & Molecular Biology, Michigan State University, 603 Wilson Road, East Lansing, MI 48824 USA.
³ 3Department of Biosystems & Agricultural Engineering, Michigan State University, 216 Farrall Hall, East Lansing, MI 48824 USA.
⁴ Present Address: Department of Chemical and Biological Engineering, 3111 Engineering Hall, 1415 Engineering Drive, Madison, WI 53706 USA.
⁵ 6Present Address: Faculdade de Engenharia Agrícola, UNICAMP, Cândido Rondon, 501, Cidade Universitária, Campinas, São Paulo 13083-875 Brasil.
⁶ 4Department of Chemical Engineering & Materials Science, Michigan State University, 428 S. Shaw Lane, East Lansing, MI 48824 USA.
⁷ 8Present Address: Sustainable Biofuels and Co-Products Research Unit, Eastern Regional Research Center, USDA, ARS, 600 E. Mermaid Lane, Wyndmoor, PA 19038 USA.
⁸ 5Division of Sustainable Process Engineering, Luleå University of Technology, 98187 Luleå, Sweden.
⁹ 9Present Address: Chemical and Biological Engineering Department, Montana State University, PO Box 173920, Bozeman, MT 59717 USA.

Abstract

Background: When applied to recalcitrant lignocellulosic feedstocks, multi-stage pretreatments can provide more processing flexibility to optimize or balance process outcomes such as increasing delignification, preserving hemicellulose, and maximizing enzymatic hydrolysis yields. We previously reported that adding an alkaline pre-extraction step to a copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment process resulted in improved sugar yields, but the process still utilized relatively high chemical inputs (catalyst and H₂O₂) and enzyme loadings. We hypothesized that by increasing the temperature of the alkaline pre-extraction step in water or ethanol, we could reduce the inputs required during Cu-AHP pretreatment and enzymatic hydrolysis without significant loss in sugar yield. We also performed technoeconomic analysis to determine if ethanol or water was the more cost-effective solvent during alkaline pre-extraction and if the expense associated with increasing the temperature was economically justified.

Results: After Cu-AHP pretreatment of 120 °C NaOH-H₂O pre-extracted and 120 °C NaOH-EtOH pre-extracted biomass, approximately 1.4-fold more total lignin was solubilized (78% and 74%, respectively) compared to the 30 °C NaOH-H₂O pre-extraction (55%) carried out in a previous study. Consequently, increasing the temperature of the alkaline pre-extraction step to 120 °C in both ethanol and water allowed us to decrease bipyridine and H₂O₂ during Cu-AHP and enzymes during hydrolysis with only a small reduction in sugar yields compared to 30 °C alkaline pre-extraction. Technoeconomic analysis indicated that 120 °C NaOH-H₂O pre-extraction has the lowest installed ($246 million) and raw material ($175 million) costs compared to the other process configurations.

Conclusions: We found that by increasing the temperature of the alkaline pre-extraction step, we could successfully lower the inputs for pretreatment and enzymatic hydrolysis. Based on sugar yields as well as capital, feedstock, and operating costs, 120 °C NaOH-H₂O pre-extraction was superior to both 120 °C NaOH-EtOH and 30 °C NaOH-H₂O pre-extraction.

Keywords: Alkaline hydrogen peroxide (AHP); Biofuels; Copper; Hybrid poplar; Lignin; Lignocellulosic biomass; Oxidative delignification; Technoeconomic analysis (TEA).