Methods and systems for producing sugars from carbohydrate-rich substrates
First Claim
1. A process for producing sugar monomers and/or polymers from a carbohydrate-rich substrate, said process comprising the steps of:
- (a) providing a carbohydrate-rich substrate and an aqueous solution containing a hydrolysis catalyst, and maintaining a gas pressure above said carbohydrate-rich substrate at an evacuation pressure and for an evacuation time to infuse said hydrolysis catalyst into said carbohydrate-rich substrate at an infusion temperature, thereby generating a reaction mixture;
(b) exposing said reaction mixture to a gas-phase reaction pressure that is higher than said evacuation pressure;
(c) maintaining said reaction mixture at a reaction temperature for a reaction time to generate said sugar monomers and/or polymers within lumen space of said carbohydrate-rich substrate;
(d) exposing said reaction mixture to a gas-phase expulsion pressure that is lower than said reaction pressure, to pump said sugar monomers and/or polymers out of said lumen space and into said aqueous solution;
(e) maintaining said reaction mixture at an expulsion temperature for an expulsion time;
(f) repeating steps (b) to (e) for at least two pressure cycles to remove, by a pumping mechanism, said sugar monomers and/or polymers from said lumen space; and
(g) recovering said sugar monomers and/or polymers from said aqueous solution;
wherein said process does not include steam explosion or ammonia fiber expansion of said carbohydrate-rich substrate.
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Abstract
A method for producing sugars from lignocellulosic biomass is provided. Lignocellulosic biomass is composed of lignocellulosic fibers which are hollow and primarily contain cellulose, hemicellulose and lignin. Lignin is concentrated in the outer fiber wall and glues the fibers into bundles, but the inner fiber wall has a much lower concentration of lignin and has more easily accessible cellulose and hemicellulose. This method uses vacuum infusion to infuse homogeneous reagents into the lumen (hollow center) of lignocellulosic fibers to hydrolyze the hemicellulose and cellulose to produce sugars and oligomers, and then uses cycles of vacuum pressure to pump these homogeneous reagents and sugars and oligomers into and out of the lumen. Some types of reagents are dilute acids, cellulase enzymes, hemicellulase enzymes, Fenton or Fenton-like reagents, and hydrogen peroxide. These reagents are homogenized by mixing the reagents with process water using turbulent mixing to produce a homogeneous reagent.
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Citations
25 Claims
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1. A process for producing sugar monomers and/or polymers from a carbohydrate-rich substrate, said process comprising the steps of:
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(a) providing a carbohydrate-rich substrate and an aqueous solution containing a hydrolysis catalyst, and maintaining a gas pressure above said carbohydrate-rich substrate at an evacuation pressure and for an evacuation time to infuse said hydrolysis catalyst into said carbohydrate-rich substrate at an infusion temperature, thereby generating a reaction mixture; (b) exposing said reaction mixture to a gas-phase reaction pressure that is higher than said evacuation pressure; (c) maintaining said reaction mixture at a reaction temperature for a reaction time to generate said sugar monomers and/or polymers within lumen space of said carbohydrate-rich substrate; (d) exposing said reaction mixture to a gas-phase expulsion pressure that is lower than said reaction pressure, to pump said sugar monomers and/or polymers out of said lumen space and into said aqueous solution; (e) maintaining said reaction mixture at an expulsion temperature for an expulsion time; (f) repeating steps (b) to (e) for at least two pressure cycles to remove, by a pumping mechanism, said sugar monomers and/or polymers from said lumen space; and (g) recovering said sugar monomers and/or polymers from said aqueous solution; wherein said process does not include steam explosion or ammonia fiber expansion of said carbohydrate-rich substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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- 23. A method of producing sugar monomers and/or polymers from a carbohydrate-rich substrate having lumen space, said method comprising hydrolyzing said carbohydrate-rich substrate in the presence of an aqueous solution containing a hydrolysis catalyst, and cycling gas pressure between a reaction pressure and an expulsion pressure for at least three pressure cycles, wherein at said reaction pressure, said sugar monomers and/or polymers are generated within said lumen space, and wherein at said expulsion pressure, said sugar monomers and/or polymers are pumped out of said lumen space and into said aqueous solution, wherein said method does not include steam explosion or ammonia fiber expansion of said carbohydrate-rich substrate.
Specification