Sugar – starch – and carbohydrates – Processes – Carbohydrate manufacture and refining
Reexamination Certificate
2001-02-23
2004-02-17
Brunsman, David (Department: 1755)
Sugar, starch, and carbohydrates
Processes
Carbohydrate manufacture and refining
C435S105000
Reexamination Certificate
active
06692578
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to converting biomass material into commercially valuable intermediate or end products via hydrolysis.
BACKGROUND OF THE INVENTION
Biomass wastes and byproducts are generated by numerous manufacturing processes, municipality operations, and food and agricultural processing. Disposal of such biomass material is becoming an increasing problem. Agribusiness and chemical industries as well as government agencies have considerable interest in converting biomass material to higher value materials and in reducing the amount of biomass material requiring disposal. A need exists for an inexpensive, robust process for obtaining higher value products from biomass materials while simultaneously reducing the amount of biomass material.
Biomass materials that include hemicellulose and cellulose are particularly important since they are so prevalent. A common example of such material is the waste and byproducts from grain processing such as the stalks and leaves of the grain plant. Corn fiber, a byproduct of corn wet milling, and wheat stubble are two large volume biomass materials that include hemicellulose and cellulose. Corn fiber typically includes, approximately, 60 weight % fibrous material (primarily polysaccharides), 20 weight % starch, 10 weight % protein, 6 weight % ash, 2 weight % fat and smaller quantities of lignin and organic acids. The fibrous material component of corn fiber typically includes approximately 60 weight % hemicellulose, 30 weight % cellulose, 8 weight % galactan and 2 weight % mannan. Currently, corn fiber is supplemented with protein and sold as low value livestock feed. However, as noted above, a large component of corn fiber is hemicellulose. Livestock are unable to digest hemicellulose and, thus, much of the mass of corn fiber is of no nutritional value. A need exists for an inexpensive, robust process to reduce the amount of hemicellulose in livestock feed.
Prior work on hydrolysis of biomass materials has focused on recovering all or nearly all of the carbohydrate value from the biomass material, including glucose from hydrolysis of the cellulose fraction of the biomass material. For example, U.S. Pat. No. 4,752,579 to Arena et al., discloses subjecting corn kernel hulls to acid hydrolysis at a temperature of 35 to 110° C. and then treating the acid hydrolysis reaction product with cellulose-degrading enzyme to complete the hydrolysis of the unreacted cellulose. The initial acid hydrolysis is said to produce a liquid portion that includes monosaccharides (chiefly D-glucose, D-xylose and L-arabinose). Arena et al., also state that the acid hydrolysis reaction product may be separated into liquid and solid portions prior to subjecting the solids portion to enzymatic hydrolysis. Similarly, U.S. Pat. No. 5,628,830 to Brink discloses hydrolyzing a biomass material under conditions to hydrolyze the hemicellulose content without substantial hydrolysis of the cellulosic content, then subjecting residual solid biomass to enzymatic hydrolysis to convert the cellulose to glucose. U.S. Pat. No. 5,536,325 to Brink discloses a non-enzymatic hydrolysis that involves subjecting a biomass material to a first stage hydrolysis at 140-220° C. and pH of 2.0-3.0 to cause hydrolysis of the hemicellulose, contacting the resultant intermediate with air at 140-220° C., followed by a second stage hydrolysis at 160-240° C.
SUMMARY OF THE INVENTION
The present invention provides for selective hydrolysis of the hemicellulose component of a biomass material. The selective hydrolysis produces water-soluble small molecules, particularly monosaccharides that can serve as precursors to higher value chemicals. In particular, the method converts at least a portion of the hemicellulose component of the biomass material into an aqueous product stream that is rich in monosaccharides. The method additionally reduces the quantity of residual water insoluble biosolids requiring further processing or disposal.
According to a first embodiment of the invention, there is provided a method for hydrolyzing hemicellulose present in a biomass material comprising solubilizing at least a portion of the hemicellulose and subsequently hydrolyzing the solubilized hemicellulose to produce at least one monosaccharide.
According to a second embodiment of the invention, there is provided a method for hydrolyzing hemicellulose present in a biomass material comprising solubilizing at least a portion of the hemicellulose and subsequently enzymatically hydrolyzing the solubilized hemicellulose to produce at least one monosaccharide.
According to a third embodiment of the invention, there is provided a method for hydrolyzing hemicellulose in a biomass material comprising solubilizing at least a portion of the hemicellulose by heating the biomass material to greater than 110° C. resulting in a water insoluble solids fraction and an aqueous fraction that includes the solubilized hemicellulose and subsequently separating the aqueous fraction from the water insoluble solids fraction.
A further advantage of the invention is that the solubilized hemicellulose is easily separated from the water insoluble solid components of the biomass material such as cellulose and protein. Such solid portion can be used as an improved livestock feed since it includes a lower amount of hemicellulose than conventional livestock feed. In particular, according to a fourth embodiment of the invention there is provided a method for making a composition that includes cellulose, at least one protein and less than about 30 weight %, hemicellulose, the method comprising solubilizing at least a portion of hemicellulose present in a biomass material that also includes cellulose and at least one protein and subsequently separating the solubilized hemicellulose from the cellulose and at least one protein.
The hydrolysis conditions described below in more detail for hydrolyzing the hemicellulose are milder (e.g., lower temperature, less acid) than those necessary to hydrolyze cellulose. Moreover, valuable monomers such as monosaccharides are rapidly hydrolyzed at the conditions for hydrolyzing cellulose. Thus, the present methods provide for hydrolyzation of the hemicellulose with no or only nominal hydrolyzation of the cellulose.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The biomass material may be any cellulosic material that includes hemicellulose. Such materials include plant fiber and wood fiber. The process is especially effective with grain fibers such as corn, wheat, rice, oats or barley. The biomass material can be byproducts and waste generated from agricultural or food processing. One type of biomass material that is particularly suitable for use with the invention is corn fiber.
Preferably, an aqueous slurry of raw or pretreated biomass material is utilized as the starting material for all embodiments of the invention. The aqueous slurry may be prepared by any conventional means such as by simply mixing the biomass material with water. The amount of water used in the slurry is not critical and can vary widely. For example, the weight % of biomass material mixed in the water can range from about 5 to 30.
The hydrolysis of the biomass material according to all embodiments of the invention results in at least two product fractions or streams. One product fraction is an aqueous composition that includes water-soluble monosaccharides as the primary component (i.e., the highest amount component other than water). The aqueous product fraction may also possibly include residual disaccharides or oligosaccharides. The other product fraction is a mixture of water insoluble (at room temperature) solids, primarily cellulose and protein. In other words, cellulose and protein are substantially non-hydrolyzed by the inventive methods.
Illustrative monosaccharides in the aqueous product stream are pentoses (for example, xylose and arabinose) and hexoses (for example, glucose, mannose and galactose). In the instance of corn fiber as the biomass material, xylose and arabinose are present in the highest amo
Alnajjar Mikhail
Franz James A.
Orth Rick J.
Schmidt Andrew J.
Battelle (Memorial Institute)
Brunsman David
Klarquist & Sparkman, LLP
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