Liquid purification or separation – Processes – Liquid/liquid solvent or colloidal extraction or diffusing...
Reexamination Certificate
2002-03-22
2004-03-23
Drodge, Joseph (Department: 1723)
Liquid purification or separation
Processes
Liquid/liquid solvent or colloidal extraction or diffusing...
C210S180000, C210S182000, C210S511000, C210S669000, C210S774000, C422S256000, C424S734000, C426S425000, C426S429000
Reexamination Certificate
active
06709595
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and an installation allowing, industrially, the setting in adsorbed state, on a porous support, of certain active compounds contained in natural or synthetic products. More precisely, such an operation will be effected after a preliminary phase during which said active compounds will be extracted from these products with the aid of a solvent taken to supercritical pressure, i.e. a fluid in supercritical state or a subcritical liquid.
In effect, it is known that bodies are generally known in three states, namely solid, liquid or gaseous, and that one passes from one to the other by varying the temperature and/or the pressure. Now, there is a point beyond which one can pass from the liquid state to the gaseous or vapour state without passing via a boiling or, inversely, a condensation, but continuously: this point is called the critical point.
It is also known that a fluid in supercritical state, i.e. a fluid which is in a state characterized either by a pressure and a temperature respectively greater than the critical pressure and temperature in the case of a pure body, or by a representative point (pressure, temperature) located beyond the envelope of the critical points shown in a diagram (pressure, temperature) in the case of a comparison with that observed in this same fluid in the state of compressed gas. The same applies to the so-called “subcritical” liquids, i.e. liquids which are in a state characterized either by a pressure higher than the critical pressure and by a temperature lower than the critical temperature in the case of a pure body, or by a pressure higher than the critical pressures and a temperature lower than the critical temperatures of the components in the case of a mixture (cf. on this subject the article by Michel PERRUT—Les Techniques de l'Ingénieur “Extraction by supercritical fluid, J 2 770-1 to Dec. 1999”).
The considerable and modulatable variations of the solvent power of the supercritical fluids are, moreover, used in numerous methods of extraction (solid/fluid), fractionation (liquid/fluid), analytical or preparative chromatography, treatment of materials (ceramics, polymers . . . ). Chemical or biochemical reactions are also made in such solvents. It should be noted that the physico-chemical properties of carbon dioxide as well as its critical parameters (critical pressure: 7.4 MPa and critical temperature: 31° C.) make of it the preferred solvent in numerous applications, all the more so as it does not present any toxicity and is available at very low price in very large quantities. Non-polar solvent, the carbon dioxide taken to supercritical pressure sometimes has a co-solvent added thereto, constituted in particular by a polar organic solvent whose function is to considerably modify the solvent power, especially with respect to molecules presenting a certain polarity, ethanol often being used to that purpose. However, certain compounds are more favourably extracted with a light hydrocarbon having from 2 to 5 carbon atoms, and more favourably, from 2 to 4 carbon atoms, at supercritical pressure.
One of the principal advantages of the methods using fluids at supercritical pressure as solvents resides in the facility of effecting the separation between the solvent and the extracts and solutes, as has been described in numerous publications and, for certain important aspects of implementation, in French Patent FR-A-2 584 618. The interesting properties of these fluids have, moreover, been used for a long time in solid-fluid extraction and liquid-fluid fractionation, as has been described in the article mentioned above.
In the event of the extracts or solutes comprising very volatile products, such as odorant products, the mere separation by partial decompression bringing about separation of the solutes and their collection by phase separation with the fluid, is not very efficient and the fluid, even partially decompressed, still contains substantial quantities of such substances. In order to separate these substances from the fluid before its recycling, it is known to use an adsorbent bed which will fix these substances and purify the fluid, as described for example in Japanese Patent JP-A-02139003.
Finally, it is known that the extraction of natural products by a fluid at supercritical pressure leads to extracts of very high quality which are increasingly used in numerous applications. However, such extracts, lie, moreover, the extracts obtained with other means such as for example extraction by organic solvent, are often in the form of very viscous or even pasty products which are not easy to handle, with the result that their incorporation in solid supports, the dosage and the mixture with a matrix and possibly other active principles, within a solid excipient, are very difficult. One is sometimes obliged to place them in solution in an organic solvent in order to effect impregnation of a solid excipient, which is regrettable since there thus disappears a determining advantage in numerous applications for which any contact of the product with an organic solvent is to be avoided.
SUMMARY OF THE INVENTION
The present invention has for its object to propose means making it possible, for purposes of industrial production, to extract active principles, particularly of pharmaceutical, cosmetological, dietetic interest, from diverse raw materials in which they are diluted, in variable concentration, depending on the origin of these raw materials and the period of their harvesting, as is always the case for products of natural origin, and to fix the extract obtained in the course of extraction in an adequate porous matrix by impregnation in one and the same operation.
According to the invention, the operation of extraction by fluid at supercritical pressure is coupled with a second operation during which the separation of the extract mixed with the solvent fluid and the impregnation of a porous medium by this extract are effected simultaneously.
The present invention thus has for its object a method for setting in adsorbed state, on a porous support, compounds contained in a product, in which, during a first step, the extraction of the compounds is effected by contacting the product with at least one solvent fluid at supercritical pressure leading to the obtaining of a mixture of extracts and of solvent fluid, characterized in that, in a second step, the water contained in the mixture of extracts and of solvent fluid is eliminated, the temperature and pressure conditions are adjusted so as to obtain, in an enclosure, two phases, namely a first phase essentially constituted by the solvent fluid in the gaseous state and a second phase constituted by a mixture of liquids formed by solvent fluid and extracts of the product, these two phases are made to trickle through a porous support adapted to adsorb the extracts, the solvent fluid contained in the second phase is vaporized.
The elimination of the water will preferably be ensured by causing the mixture of extracts and of solvent fluid to trickle over a bed of adsorbent product adapted to fix the water selectively.
The solvent fluid may be constituted by pure carbon dioxide, nitrogen protoxide or a light hydrocarbon counting from 2 to 4 carbon atoms. The solvent fluid may be pure or possibly have one of more co-solvents added thereto. For example, the solvent fluid may in particular be constituted by a mixture of carbon dioxide with at least one co-solvent constituted by an alcohol and preferably ethanol, by a ketone and preferably acetone, by an ester and preferably ethyl acetate.
The first step of extraction may preferably be effected at a pressure included between 7.4 MPa and 80 Mpa, and preferably between 10 MPa and 40 MPa, and at a temperature included between 0° C. and 80° C. Similarly, the trickling of the two phases through the porous support may be effected at a pressure included between 1 MPa and 10 MPa, and preferably between 4 MPa and 8 Mpa, and at a temperature included between 0° C. and 80° C.
The present inventio
Majewski Wieslaw
Perrut Michel
Dechert LLP
Drodge Joseph
Separex (Societe Anonyme)
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