Reductive Catalytic Fractionation of Corn Stover Lignin
Reductive catalytic fractionation (RCF) has emerged as an effective biomass pretreatment strategy to depolymerize lignin into tractable fragments in high yields. We investigate the RCF of corn stover, a highly abundant herbaceous feedstock, using carbon-supported Ru and Ni catalysts at 200 and 250 °...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | en_US |
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American Chemical Society (ACS)
2017
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| Online Access: | http://hdl.handle.net/1721.1/109695 https://orcid.org/0000-0001-5535-5405 https://orcid.org/0000-0002-0025-4233 |
| _version_ | 1826208043384176640 |
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| author | Katahira, Rui Reed, Michelle Resch, Michael G. Karp, Eric M. Beckham, Gregg T. Anderson, Eric Michael Roman, Yuriy |
| author2 | Massachusetts Institute of Technology. Department of Chemical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Chemical Engineering Katahira, Rui Reed, Michelle Resch, Michael G. Karp, Eric M. Beckham, Gregg T. Anderson, Eric Michael Roman, Yuriy |
| author_sort | Katahira, Rui |
| collection | MIT |
| description | Reductive catalytic fractionation (RCF) has emerged as an effective biomass pretreatment strategy to depolymerize lignin into tractable fragments in high yields. We investigate the RCF of corn stover, a highly abundant herbaceous feedstock, using carbon-supported Ru and Ni catalysts at 200 and 250 °C in methanol and, in the presence or absence of an acid cocatalyst (H₃PO₄ or an acidified carbon support). Three key performance variables were studied: (1) the effectiveness of lignin extraction as measured by the yield of lignin oil, (2) the yield of monomers in the lignin oil, and (3) the carbohydrate retention in the residual solids after RCF. The monomers included methyl coumarate/ferulate, propyl guaiacol/syringol, and ethyl guaiacol/syringol. The Ru and Ni catalysts performed similarly in terms of product distribution and monomer yields. The monomer yields increased monotonically as a function of time for both temperatures. At 6 h, monomer yields of 27.2 and 28.3% were obtained at 250 and 200 °C, respectively, with Ni/C. The addition of an acid cocatalysts to the Ni/C system increased monomer yields to 32% for acidified carbon and 38% for phosphoric acid at 200 °C. The monomer product distribution was dominated by methyl coumarate regardless of the use of the acid cocatalysts. The use of phosphoric acid at 200 °C or the high temperature condition without acid resulted in complete lignin extraction and partial sugar solubilization (up to 50%) thereby generating lignin oil yields that exceeded the theoretical limit. In contrast, using either Ni/C or Ni on acidified carbon at 200 °C resulted in moderate lignin oil yields of ca. 55%, with sugar retention values >90%. Notably, these sugars were amenable to enzymatic digestion, reaching conversions >90% at 96 h. Characterization studies on the lignin oils using two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance and gel permeation chromatrography revealed that soluble oligomers are formed via solvolysis, followed by further fragmentation on the catalyst surface via hydrogenolysis. Overall, the results show that clear trade-offs exist between the levels of lignin extraction, monomer yields, and carbohydrate retention in the residual solids for different RCF conditions of corn stover. |
| first_indexed | 2024-09-23T13:59:37Z |
| format | Article |
| id | mit-1721.1/109695 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T13:59:37Z |
| publishDate | 2017 |
| publisher | American Chemical Society (ACS) |
| record_format | dspace |
| spelling | mit-1721.1/1096952022-10-01T18:25:52Z Reductive Catalytic Fractionation of Corn Stover Lignin Katahira, Rui Reed, Michelle Resch, Michael G. Karp, Eric M. Beckham, Gregg T. Anderson, Eric Michael Roman, Yuriy Massachusetts Institute of Technology. Department of Chemical Engineering Anderson, Eric Michael Roman, Yuriy Reductive catalytic fractionation (RCF) has emerged as an effective biomass pretreatment strategy to depolymerize lignin into tractable fragments in high yields. We investigate the RCF of corn stover, a highly abundant herbaceous feedstock, using carbon-supported Ru and Ni catalysts at 200 and 250 °C in methanol and, in the presence or absence of an acid cocatalyst (H₃PO₄ or an acidified carbon support). Three key performance variables were studied: (1) the effectiveness of lignin extraction as measured by the yield of lignin oil, (2) the yield of monomers in the lignin oil, and (3) the carbohydrate retention in the residual solids after RCF. The monomers included methyl coumarate/ferulate, propyl guaiacol/syringol, and ethyl guaiacol/syringol. The Ru and Ni catalysts performed similarly in terms of product distribution and monomer yields. The monomer yields increased monotonically as a function of time for both temperatures. At 6 h, monomer yields of 27.2 and 28.3% were obtained at 250 and 200 °C, respectively, with Ni/C. The addition of an acid cocatalysts to the Ni/C system increased monomer yields to 32% for acidified carbon and 38% for phosphoric acid at 200 °C. The monomer product distribution was dominated by methyl coumarate regardless of the use of the acid cocatalysts. The use of phosphoric acid at 200 °C or the high temperature condition without acid resulted in complete lignin extraction and partial sugar solubilization (up to 50%) thereby generating lignin oil yields that exceeded the theoretical limit. In contrast, using either Ni/C or Ni on acidified carbon at 200 °C resulted in moderate lignin oil yields of ca. 55%, with sugar retention values >90%. Notably, these sugars were amenable to enzymatic digestion, reaching conversions >90% at 96 h. Characterization studies on the lignin oils using two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance and gel permeation chromatrography revealed that soluble oligomers are formed via solvolysis, followed by further fragmentation on the catalyst surface via hydrogenolysis. Overall, the results show that clear trade-offs exist between the levels of lignin extraction, monomer yields, and carbohydrate retention in the residual solids for different RCF conditions of corn stover. National Science Foundation (U.S.) (1454299) 2017-06-07T13:26:10Z 2017-06-07T13:26:10Z 2016-09 2016-08 Article http://purl.org/eprint/type/JournalArticle 2168-0485 http://hdl.handle.net/1721.1/109695 Anderson, Eric M.; Katahira, Rui; Reed, Michelle; Resch, Michael G.; Karp, Eric M.; Beckham, Gregg T. and Román-Leshkov, Yuriy. “Reductive Catalytic Fractionation of Corn Stover Lignin.” ACS Sustainable Chemistry & Engineering 4, no. 12 (December 2016): 6940–6950 © 2016 American Chemical Society https://orcid.org/0000-0001-5535-5405 https://orcid.org/0000-0002-0025-4233 en_US http://dx.doi.org/10.1021/acssuschemeng.6b01858 ACS Sustainable Chemistry & Engineering Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) MIT Web Domain |
| spellingShingle | Katahira, Rui Reed, Michelle Resch, Michael G. Karp, Eric M. Beckham, Gregg T. Anderson, Eric Michael Roman, Yuriy Reductive Catalytic Fractionation of Corn Stover Lignin |
| title | Reductive Catalytic Fractionation of Corn Stover Lignin |
| title_full | Reductive Catalytic Fractionation of Corn Stover Lignin |
| title_fullStr | Reductive Catalytic Fractionation of Corn Stover Lignin |
| title_full_unstemmed | Reductive Catalytic Fractionation of Corn Stover Lignin |
| title_short | Reductive Catalytic Fractionation of Corn Stover Lignin |
| title_sort | reductive catalytic fractionation of corn stover lignin |
| url | http://hdl.handle.net/1721.1/109695 https://orcid.org/0000-0001-5535-5405 https://orcid.org/0000-0002-0025-4233 |
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