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Ref country code : MK. Ref country code : BG. Ref country code : AL. The use of these catalysts allows to obtain directly from the high selectivity lactic acid while limiting the production of oligosaccharides and soluble polymers. In recent years, there is a renewal of interest for the incorporation of renewable products in the fuel and chemical industries, in addition to or instead of fossil products. One possible way is the conversion of the cellulose contained in the lignocellulosic biomass, chemicals or intermediates, such as lactic acid.
The term lignocellulosic biomass BLC or lignocellulose includes several products present in varying amounts depending on its origin: cellulose, hemicellulose and lignin. The hemicellulose and the cellulose are the carbohydrate portion of the lignocellulose. These are polymers of sugars hexoses and pentoses. Lignin is a phenolic macromolecule rich motifs. For lignocellulosic biomass products from forestry and by-products from agriculture such as straw and some plants dedicated to high agricultural output is meant for example.
Production of chemicals from lignocellulosic biomass allows both to reduce energy dependence on dependence on oil and protect the environment through the reduction of greenhouse gas emissions without the use of resources for food uses. Direct transformation of lignocellulosic biomass or cellulose in chemical products or intermediates, as the lactic acid, is a particularly advantageous way.
By direct conversion is meant the cellulose processing - lactic acid without through glucose. Lactic acid is a carboxylic acid, its chemical formula is C 3 H 6 O 3 and its structure is reflected in its systematic name, 2-hydroxy-propanoic acid. As it has an asymmetric carbon, there are two enantiomers of lactic acid. The applications of lactic acid are mainly those of the polymer PLA poly lactic acid as a food preservative but also as biodegradable polymers, pesticides and herbicides.
La production de l'acide lactique peut se faire par voie chimique ou par voie biologique.
The production of lactic acid can be chemically or biologically. Chemical methods for producing the lactic acid known to those skilled in the art are made via the transformation of petrochemical intermediates such as the hydrolysis of lactonitrile or hydration of propionic acid. Lactic acid can also be produced by fermentation of polysaccharides, which can be produced from biomass, eg from cereals such as wheat or corn. A method for producing lactic acid by fermentation of a sugar cane extract, by means of microorganism belonging to Bacillus or Sporolactobacillus genres.
The valuation of the lignocellulosic biomass or cellulose in the biomass in heterogeneous catalysis is described in the literature.
Rinaldi et al. EP Zeng et al. There is no method that allows a direct processing, i.
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The Applicant has discovered a method of direct conversion of the cellulose present in the lignocellulosic biomass to lactic acid, employing heterogeneous catalysts dispersed tungsten based on an oxide carrier s. In addition, this method allows to obtain a high yield of lactic acid. The invention consists of a method for conversion of lignocellulosic biomass or cellulose in the lactic acid in the presence of water, employing heterogeneous catalysts dispersed tungsten based on an oxide carrier s.
The method allows to obtain high conversions of reactive and substantial selectivities, especially high yields of lactic acid, while limiting the formation of oligosaccharides or of water-soluble polymers. These conversions and selectivities are obtained in hydrothermal conditions presence of water and in the presence of tungsten catalysts having Lewis type acid properties. The use of these catalysts allows to obtain directly from lactic acid in high selectivity while minimizing the production of oligosaccharides and soluble polymers. Lignocellulosic biomass is essentially comprised of three natural components present in variable amounts depending on its origin: cellulose, hemicellulose and lignin.
Cellulose is insoluble in water at ambient temperature and pressure. Contrary to cellulose, this polymer is predominantly composed of monomers pentoses five carbon cycles and hexoses 6 carbon cycles. Hemicellulose is an amorphous heteropolymer with a degree of polymerization less than that of cellulose and which is generally soluble in water. Its function is the mechanical reinforcement, and support repellent plants. This macromolecule rich in phenolic units can be described as resulting from the combination of three monomeric units propyl-methoxy-phenol type.
The lignocellulosic feedstock may be made of wood or plant waste. Other nonlimiting examples of lignocellulosic biomass material are farm residues straw, grass rods, cores, shells The filler used in the method according to the invention is of lignocellulosic biomass or cellulose. Cellulose used may be crystalline or amorphous. Load lignocellulosic biomass can be used in its crude form, i. Raw biomass is generally in the form of fiber or powder residues.
In general, it is ground to allow the transport of it shredding. Load lignocellulosic biomass may also be used in its pretreated form, i. Biomass preferably undergoes a pretreatment to increase the responsiveness and accessibility of the cellulose in the biomass before processing. Mechanical treatments go beyond the simple shredding because they alter the chemical structure of the components. They improve the accessibility and responsiveness of cellulose by its decristallinisation and the increase of the exchange surface.
Mechanical treatments include reducing the size of the elementary fibers or particles, for example by chipping biomass using a cutter, by grinding the biomass adjustment of the particle size , destructuring of press chips or defibration abrasive chips, after preheating. Mechanical treatments can be operated in decentralized mode near the production of biomass or in centralized mode directly fueling the transformation. Other treatments include thermochemical treatments solvent hot ethanol or roasting can be defined as a moderate temperature pyrolysis and controlled residence time because it is accompanied by partial destruction of the lignocellulosic material.
The known technologies for roasting are for example rotary kiln, moving bed, fluidized bed, the worm heated, the contact metal ball providing heat. These technologies can optionally use a gas flowing against or co stream such as nitrogen or any other inert gas under the conditions of the reaction.
The thermo-mechanical-chemical treatments include steam treatments steam explosion called hydrolysis or even flash "steam explosion" , the AFEX treatment ammonia fiber explosion with ammonia or twin-screw extrusion various chemical reagents. Pretreatment is used to prepare the lignocellulosic biomass by separating the carbohydrate portion of the lignin and adjusting the size of the biomass particles to be treated.
The size of the biomass particles after the pretreatment is usually less than 5 mm, preferably less than microns. Generally, the acidity of a catalyst is the result of two types of combined acidity: Lewis acidity, characterized by the presence of an electronic gap on one atom, and a Bronsted acidity, characterized the ability to donate a proton.
The catalysts used in the process according to the present invention can be synthesized by ion exchange, by impregnation or coprecipitation followed by a heat treatment. The resulting solids have the advantages of being mesoporous and stable, heat and hydrothermal conditions. The catalysts used in the present invention may be in the form of powder, extrudates, spheres or pellets. Meta ammonium tungstate is the common precursor.
The biomass processing method lignocellulosic or cellulose according to the invention comprises reacting in a water-containing medium in the presence of the catalytic composition according to the invention. By medium containing water conventional liquid media describes eg ethanol or water and non conventional media like ionic liquids or supercritical media density liquid type. The medium may also consist entirely of water.
Preferably, the medium is water. This process can be performed in the presence of a gas selected from air, a neutral gas N 2, He, Ar This list is incomplete ; you can help by expanding it. Random House Webster's Unabridged Dictionary. Retrieved 9 December Le Horla et autres contes d'angoisse in French ed. Paris: Flammarion. Retrieved 13 March Archived from the original on 13 October The Eiffel Tower and Other Mythologies. Howard, Richard. Berkeley: University of California Press.
Appel Karel. Hagenberg, Ed. Lafayette, New York, Otmezguine, Ed. Marval, Arp Hans. Arroyo Eduardo. Mason, Ed.
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Atlan J-Michel. Gallimard, Avati Mario. Bacon Francis. Thames and Hudson, Londres, Bruno Sabatier, Paris, L'ouvrage est enrichi de quelques photographies de l'artiste et d'un parcours biographique essentiel. Baj Enrico. Electa, Milan, Baldessari John. Barnet Will. Basaldella Afro. Baselitz Georg. Hatje Cantz, Baumeister Willi. Bazaine Jean. Galerie Adrian Maeght. Beauverie Charles. L'artiste est mort en Beckmann Max. Jacob-Friesen et C. Zeiller, Ed. Staatliche Kunsthalle Karlsruhe, L'artiste a atteint une dimension universelle et intemporelle.
Belgeonne Gabriel. Belgeonne, D. Tonneau-Ryckelynck, co-Ed. L'ouvrage est clos par de nombreuses annexes biographie, expositions, distinctions, illustrations de textes, oeuvres dans les collections, bibliographie, index des titres. Bellmer Hans. Nouvelles Editions Doubleff, Flahutez, Ed. Bergman Anna-Eva. Bernard Emile. Morane, Ed. Bertemes Roger. Saint-Paul, Luxembourg, Beuys Joseph. L'ouvrage se referme sur une biographie de l'artiste. Bille Ejler. Boni Paolo. Gayzag Zakarian, Paris, Pour Boni, l'abstrait et le concret ne s'excluent nullement, et de l'un peut toujours sortir l'autre.
Bonnard Pierre. Adam Biro, Paris, Adetta et Ed. Ville du Cannet, Flammarion, Paris, Boullaire Jacques. Le Motu, Papeete, Boumeester Christine. Sireuil, Ed. Braque Georges. Sauret, Technique moins incisive que la gravure, la lithographie se rapproche sans doute plus de la peinture et donc de la couleur.
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Flammarion, L'ouvrage est clos par une notice biographique. Brauner Victor. Brown James. Bryen Camille. Loyer, Ed. Iliazd, -. Buchholz Wolff. Ouvrage en langue allemande. Buffet Bernard. Garnier, Trinckvel Draeger, Sauret, Monte-Carlo, Burri Alberto. Sarteanesi, Ed. Bury Pol. Campigli Massimo. Tavola, Ed. Graphis Arte, Meloni et L. Capogrossi Giuseppe. Cargaleiro Manuel. Fondation Manuel Cargaleiro, Carzou Jean. Cassatt Mary. Breeskin, Ed. Smithsonian Institution Press, Washington, Celle-ci sera suivie de quatre autres chez Durand-Ruel, et chez Ambroise Vollard.
Castellani Enrico. Caulfield Patrick. Alan Cristea Gallery, Londres, Cayol Pierre. Galerie M. Champetier, Cannes, Dans un ordre chronologique? Par technique? Voici le lien qui vous permettra de le consulter : CR Pierre Cayol. Chagall Marc. Maeght, Galerie Matignon, Dans la pierre lithographique ou sur une plaque de cuivre, il me semblait que je pouvais placer toutes mes tristesses, toutes mes joies.