Liquefaction cellulose

Kaufman, J.A. and Weiss, A.H., "Solid Waste Conversion Cellulose Liquefaction", Report No. EPA-670/2-75-031, Nat. Environmental Research Center, Office of R D, U.S. Environmental Protection Agency, Cincinnati (1975). 

Table III. CONDITIONS USED FOR NON BOX-BEHNKEN KINETIC STUDIES OF CELLULOSE LIQUEFACTION, 160-230°...

Table IV. CONDITIONS USED FOR FIGURES OF QC TRACES OF CELLULOSE LIQUEFACTION PRODUCTS...

For example, 1,4-addition of the acetone carbanion to acrolein would be a facile reaction under the reaction conditions used for cellulose liquefaction (both of these intermediates are formed from cellulose). The product, 5-ketohexanal, could cyclize to 3-hydroxycyclohexanone, which would then dehydrate and dehydrogenate to phenol and related aromatic products. This route to an observed product (phenol) is still speculative, but we have shown the more direct route to phenol from cyclohexanone does not occur under the... 

Table V. PRODUCTS IDENTIFIED FROM CELLULOSE LIQUEFACTION OPEN CHAIN ALIPHATICS...

Kaufman, J.A. Weiss, A.H. (1975). Solid Waste Conversion Cellulose Liquefaction. Report prepared for the US National Environmental Research Centre by the Worcester Polytechnic Institute, USA... 

Miller, I. J., Saunders, E. R. Reactions of acetaldehyde, acrolein, acetol, and related condensed compounds under cellulose liquefaction conditions. Fuel 1987,66,130-135. 

Supercritical fluid solvents have been tested for reactive extractions of liquid and gaseous fuels from heavy oils, coal, oil shale, and biomass. In some cases the solvent participates in the reactions, as in the hydrolysis of coal and heavy oils with water. Related applications include conversion of cellulose to glucose in water, dehgnincation of wood with ammonia, and liquefaction of lignin in water. 

If we compare liquefaction to maceration, more activities are needed to liquefy the cell wall. Since 1991, new pectinases activities such as rhamnogalacturonase, pectin acetylesterase and xyloglucanases complex have been found to be important in the apple liquefaction by Henck Schols, Jean-Paul Vincken and Voragen [3]. The cellulose-xyloglucan complex accounts approximatively 57% of the apple cell-wall matrix. In a liquefaction process, an efficient enzymic degradation of this complex is crucial to increase the sugars extraction, to decrease the viscosity of the pulp then to be able to ultra-filtrate the juice without second depectinisation, at last to have negative alcohol tests required by some concentrate customers. 

Various solvents are being investigated to dissolve lignocellulosic materials. Some approaches focus on the selective depolymerization and extraction of lignin and hemicellulose as pre-treatment to produce clean cellulose fibers for subsequent fermentation or for pulping. Other approaches attempt to dissolve the whole lignocellulose with or without depolymerization. The liquefaction processes that are carried out at high temperature (>300 °C), and produce a complex oil mixture, are discussed above with the pyrolysis processes. 

Over the past two decades, considerable interest has been directed toward the conversion of cellulosic biomass (such materials as wood wastes, bagasse, and straw) into useful products, notably fuels. Several procedures, including fermentation, gasification, liquefaction, and pyrolysis, have been commercially applied to carbohydrates with various degrees of success. In order to use the polysaccharides present in lignocel-lulosic materials as a substrate in fermentation processes, pretreatments are necessary, such as with steam (under slightly acid conditions) or... 

Study of the mechanism of this complex reduction-liquefaction suggests that part of the mechanism involves formate production from carbonate, dehydration of the vicinal hydroxyl groups in the cellulosic feed to carbonyl compounds via enols, reduction of the carbonyl group to an alcohol by formate and water, and regeneration of formate (46). In view of the complex nature of the reactants and products, it is likely that a complete understanding of all of the chemical reactions that occur will not be developed. However, the liquefaction mechanism probably involves catalytic hydrogenation because carbon monoxide would be expected to form at least some hydrogen by the water-gas shift reaction. 

ENZYMATIC LIQUEFACTION OF THE RAW MATERIAL. Mixtures of pectinolytic and cellulolytic enzymes are used. Together they bring about a stepwise degradation, with initial loosening and separation of the cell aggregates, then breakdown of the cell walls and finally conversion of cellulose to sugar. After liquefaction of the mash, the remaining solids are usually separated off in a decanter. 

Biomass is composed of various components such as cellulose, hemicellulose, lignin, extractives and mineral water. The composition of biomass plays a definitive role in altering the product distribution and their properties [2-3J. As is shown in earlier publications [4-S] different biomass, on pyrolysis, give different product yield with different product properties. In order to choose a biomass for a particular process (carbonisation, liquefaction, gasification or adsorbent char) knowledge on the product distribution and properties for various biomass are essential. 

Physical effects caused by polyethylene glycol bases include softening and liquefaction in mixtures with phenol, tannic acid, and salicylic acid. Discoloration of sulfonamides and dithranol can also occur and sorbitol may be precipitated from mixtures. Plastics, such as polyethylene, phenolformaldehyde, polyvinyl chloride, and cellulose-ester membranes (in filters) may be softened or dissolved by polyethylene glycols. Migration of polyethylene glycol can occur from tablet film coatings, leading to interaction with core components. 

Traditionally thermal liquefaction studies on biomass have been carried out in the presence of one or both of the reducing gases, hydrogen and carbon monoxide (2, 3 4 J5, 6). Equation 1, in which cellulose has been used to approximate the elemental composition of wood, shows that theoretically a reducing gas is not required for wood liquefaction when internal carbon is used to remove the oxygen. 

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