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Title: Enhanced rates of enzymatic saccharification and catalytic synthesis of biofuel substrates in gelatinized cellulose generated by trifluoroacetic acid

The crystallinity of cellulose is a principal factor limiting the efficient hydrolysis of biomass to fermentable sugars or direct catalytic conversion to biofuel components. We evaluated the impact of TFA-induced gelatinization of crystalline cellulose on enhancement of enzymatic digestion and catalytic conversion to biofuel substrates. Low-temperature swelling of cotton linter cellulose in TFA at subzero temperatures followed by gentle heating to 55 degrees C dissolves the microfibril structure and forms composites of crystalline and amorphous gels upon addition of ethanol. The extent of gelatinization of crystalline cellulose was determined by reduction of birefringence in darkfield microscopy, loss of X-ray diffractability, and loss of resistance to acid hydrolysis. Upon freeze-drying, an additional degree of crystallinity returned as mostly cellulose II. Both enzymatic digestion with a commercial cellulase cocktail and maleic acid/AlCl3-catalyzed conversion to 5-hydroxymethylfurfural and levulinic acid were markedly enhanced with the low-temperature swollen cellulose. Only small improvements in rates and extent of hydrolysis and catalytic conversion were achieved upon heating to fully dissolve cellulose. Low-temperature swelling of cellulose in TFA substantially reduces recalcitrance of crystalline cellulose to both enzymatic digestion and catalytic conversion. In a closed system to prevent loss of fluorohydrocarbons, the relative ease of recovery and regeneration ofmore » TFA by distillation makes it a potentially useful agent in large-scale deconstruction of biomass, not only for enzymatic depolymerization but also for enhancing rates of catalytic conversion to biofuel components and useful bio-products.« less
 [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [3] ;  [3] ; ORCiD logo [3]
  1. Purdue Univ., West Lafayette, IN (United States); Univ. of Sao Paulo (Brazil)
  2. Purdue Univ., West Lafayette, IN (United States); China Agricultural Univ., Beijing (China)
  3. Purdue Univ., West Lafayette, IN (United States)
  4. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  5. Northeastern Univ., Boston, MA (United States); Brookhaven National Lab. (BNL), Shirley, NY (United States)
  6. Northeastern Univ., Boston, MA (United States)
  7. China Agricultural Univ., Beijing (China)
Publication Date:
Report Number(s):
Journal ID: ISSN 1754-6834
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 10; Journal Issue: 1; Journal ID: ISSN 1754-6834
BioMed Central
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
09 BIOMASS FUELS; acid resistance; biofuels; crystalline materials; distillation; gelation; hydrolysis; saccharification; temperature
OSTI Identifier: