WO2002051533A1

WO2002051533A1 - Catalytic cartridge and application to installations producing catalysed chemical reactions

Info

Publication number: WO2002051533A1
Application number: PCT/FR2001/004095
Authority: WO
Inventors: Nathalie Nicolaus
Original assignee: Messier-Bugatti
Priority date: 2000-12-22
Filing date: 2001-12-20
Publication date: 2002-07-04
Also published as: FR2818562A1

Abstract

The invention concerns a catalytic cartridge (30) comprising a coherent two-dimensional texture in activated carbon fibres bearing catalyst particles or catalytic functions distributed at the surface of the fibres, the texture being formed and housed inside a casing. The cartridge (30) can be arranged in a chamber (22) integrated to a recycling loop (20) connected on a reactor vessel (10).

Description

Title of invention

Catalytic cartridge and application to installations for carrying out catalyzed chemical reactions.

Invention background

In industrial reactors intended for the implementation of catalyzed chemical reactions, it is common to incorporate the catalyst by fixing it in divided form on grains of activated carbon introduced into the reactor, within the reaction medium. At the end of the reaction, careful filtration must be carried out to avoid the presence of grains of activated carbon in the product obtained. This filtration step leads to a loss of catalyst, which is often in the form of a metal, in particular a noble metal, a loss generally of the order of 5 to 15% by mass. In addition, when the catalyst must be replaced or renewed, the recovery of the activated carbon grains contained in the reactor is a long and delicate operation.

OBJECT AND SUMMARY OF THE INVENTION The object of the invention is to remedy these drawbacks and to this end proposes the use of a catalytic cartridge comprising a coherent two-dimensional texture made of activated carbon fibers supporting catalyst particles or distributed catalytic functions. on the surface of the fibers, the texture being shaped and housed inside a housing.

The use of such a coherent texture formed in a cartridge makes it very easy to extract and replace the catalyst, since this can be done by simple manipulation of the cartridge. In addition, the entrainment of catalyst support particles is avoided, which makes it possible to dispense with the filtration step during the withdrawal of the desired reaction product, therefore eliminating the drawbacks associated with this filtration.

The carbon fiber texture can be produced in different ways to present a two-dimensional and coherent character. Advantageously, a texture will be used in the form of activated carbon fabric. Other types of textures are however usable, for example knitted textures or unidirectional or multidirectional tablecloths. The latter can be obtained by superposition and bonding together of several unidirectional layers, the directions of the superimposed layers being different from each other.

The attachment of catalyst particles to the fibers of the activated carbon texture can be carried out by several methods known in themselves, such as cation exchange or liquid impregnation. We can also develop surface functions on activated carbon fibers to confer catalytic properties.

In order to provide a high contact surface with the reaction medium, the activated carbon fiber texture is advantageously wound in superimposed turns or in the form of a pleated strip. The texture can be placed around a central passage connected to an inlet or outlet of the reaction medium in or out of the cartridge. The central passage can be materialized by a tube with a porous wall closed at one end.

To facilitate keeping the texture in shape, it can have at least one of its faces fixed to a porous support structure in sheet form such as a grid or a porous membrane. Such a support structure also has the advantage of avoiding possible tearing of fibers which can then be entrained in the reaction medium.

The invention also relates to an industrial installation comprising a reactor vessel, at least one catalytic cartridge as defined above and means for ensuring circulation of the reaction medium in contact with the texture of activated carbon fibers.

The circulation of the reaction medium can be ensured by an agitator inside the reactor vessel, the catalytic cartridge being housed in this vessel.

As a variant, the installation comprises a circulation loop external to the reactor vessel and a pump for circulating the reaction medium in a closed circuit through the reactor vessel and the circulation loop. The catalytic cartridge can then be placed inside the reactor vessel or inside a chamber integrated into the circulation loop. This latter arrangement is advantageous because it allows the use of catalytic cartridges in accordance with the invention with existing reactor vessels, without significant modifications to them, and it also allows easy installation and removal of the cartridge. .

The circulation loop may then have at least two branches arranged in parallel and each comprising a chamber for receiving at least one catalytic cartridge, means being provided for directing the reaction medium selectively towards one or the other branch. It is thus possible to remove and replace a catalytic cartridge without interrupting the circulation of the reaction medium.

Brief description of the drawings

The invention will be better understood on reading the description given below, by way of indication but not limitation, with reference to the appended drawings in which: - the figurel is a very schematic view of an installation for the production of a catalyzed chemical reaction, according to an embodiment of the invention;

- Figure 2 is a detail view on an enlarged scale and in section of a chamber containing a catalytic cartridge in the installation of Figure 1;

- Figure 3 is a sectional view along the plane III-III of Figure 2;

- Figure 4 is a cross-sectional view of an alternative embodiment of a catalytic cartridge according to the invention;

- Figure 5 is a sectional view along the plane V-V of Figure 6 of a chamber containing several catalytic cartridges, according to an alternative embodiment of the installation of Figure 1;

- Figure 6 is a sectional view along the plane VI-VI of Figure 5; - Figure 7 is a very schematic view of another alternative embodiment of the installation of Figure 1;

- Figure 8 is a very schematic view of an installation for carrying out a catalyzed chemical reaction, according to another embodiment of the invention; and

- Figure 9 is a very schematic view of an installation for carrying out a catalyzed chemical reaction, according to yet another embodiment of the invention.

Detailed description of embodiments of the invention

The installation of FIG. 1 comprises a reactor vessel 10 intended to contain a liquid reaction mixture which can be brought into contact with a gas under pressure. The tank is closed by a cover 12. This can be provided with a passage for the connection of a pipe 13 for supplying a possible reaction gas. An agitator 14 is immersed in the reaction mixture to keep it in motion in the tank 10. The drive of the agitator 14 in rotation is provided by a motor 16 coupled to a rod 15 supporting the agitator 14 through the cover 12. An outlet pipe 17 is connected to a withdrawal orifice located at the bottom of the tank 10 in order to extract the product obtained at the end of the reaction.

A circulation loop 20 is connected to the reactor 10, outside of it. The circulation loop 20 comprises a pipe 21 which plugs into the outlet pipe 17 and connects it to an inlet of a chamber 22. A pump 23 is mounted on the pipe 21. The loop 20 also includes a return pipe 24 which connects an outlet from the chamber 22 to the reactor, through a passage formed in the cover 12. The chamber 22 has a bottom 22a into which the pipe 21 opens and a cover 22b provided with a passage communicating with the pipe 24.

A catalytic cartridge 30 (FIGS. 1, 2, 3) is housed in the chamber 22. The cartridge 30 comprises a two-dimensional texture 32 made of activated carbon fibers supporting catalyst particles or catalytic functions. The texture 32 is shaped around a central passage materialized by a tube 34 with a porous wall, for example with a multi-perforated wall. The set is housed inside a housing 35 comprising a cylindrical side wall 36 and two end flanges 37, 38. The housing is fixed to an annular flange 25 of the internal wall of the chamber 22.

In the example illustrated, the texture 32 is a strip wound on itself around the central passage 34. The flanges 37, 38 are applied against the edges of the texture 32, these being able to be guided in grooves formed in the internal faces of the flanges. The lower flange 38 located closest to the entry into the chamber 22 is full, while the upper flange 37 has a central opening 37a communicating with the upper end of the tube 34. The reaction mixture entering the chamber 22 passes through the catalytic cartridge passing through openings 36a of the side wall of the housing 36, through the texture 32 and through the wall of the tube 34 to the opening 37a which constitutes the outlet of the cartridge 30, facing the exit from the chamber 22. It will be noted that the wall 36 of the housing can be produced simply in the form of a cage made up of bars connecting the flanges 37, 38.

The material of the housing 35 and of the tube 34 is chosen according to the conditions of use, in particular temperature and chemical nature of the reaction mixture. Stainless steel may be used for high temperatures and high pressures, or plastics for lower temperatures and pressures or with corrosive media.

The texture 32 made of carbon fibers is a coherent two-dimensional texture, such as a fabric, other types of texture being however usable as indicated above.

The production of fabrics or other two-dimensional textures consistent with activated carbon fibers is known per se. A carbon fiber texture is obtained directly from carbon threads or fibers from carbon precursor threads or fibers, after heat treatment, or from a carbon precursor threads or fibers texture, heat treatment transformation of the precursor being carried out after completion of the texture. The activation of the carbon fiber texture can be carried out by heat treatment under an oxidizing atmosphere such as water vapor and / or carbon dioxide. The use of a carbon precursor under Rayon shape provides high purity carbon fibers. Processes for obtaining a carbon fiber texture and for activating such a texture are described in documents WO 99/26721 and FR 2,741,363. An activated carbon fiber texture can also be obtained directly from a texture of cellulosic fibers by heat treatment carried out after impregnation of the texture of cellulosic fibers with an agent which promotes the dehydration of cellulose. Such a method is described in document WO 98/41678. Because of its good cohesion and the possibility of obtaining it from fabrics of carbon precursors which are relatively easy to produce, a texture of carbon fibers in the form of fabric will preferably be used.

The nature of the catalyst or of the catalytic functions attached to texture 32 depends on the application envisaged.

In the case of reactions such as, for example, catalytic hydrogenation, an activated carbon fiber texture is used which supports a noble metal in divided form, such as Pd, Pt, Ru, Rh, Ir. The attachment of the catalyst to the fibers of activated carbon can be carried out by cation exchange or by liquid impregnation with a composition containing a compound of the catalyst to be fixed. Reference may be made to document WO 99/26721 of the applicant.

In other cases, such as for example for acid catalysis, surface functions such as carboxylic acids are developed on the activated carbon fibers. This is achieved by performing an oxidative treatment in the liquid phase using chemical agents such as sodium hypochlorite NaOCI or nitric acid HNO ₃ . Other types of catalysts or catalytic functions can of course be used.

The activated carbon fiber texture is shaped after fixing the catalyst or developing catalytic functions. In order to facilitate this shaping and the subsequent maintenance of the texture in the desired shape, the texture can be fixed by one of its faces on a thin porous sheet support structure having a shape memory capacity.

Such a structure 33 (shown in details in FIGS. 2 and 3) is for example a grid or a perforated membrane of plastic material such as polypropylene, polyamide, polyurethane, polyester or polyethylene.

The use of this support structure also makes it possible: to induce a pressure drop which increases the contact time of the reaction mixture with the texture of activated carbon fibers; retain any fibers torn off or isolated; homogeneously dispersing the reaction mixture on the surface of the fibrous texture by acting as a distribution grid, the structure 33 being located at least on the face of the fibrous texture receiving the reaction mixture; and to reinforce the mechanical resistance of the fibrous texture.

The texture 32 can be provided with a holding structure 33 on only one or on each of its faces. The connection between the texture 32 and the holding structure 33 can be achieved for example by gluing. Different techniques can be used such as:

- co-laminating of the texture 32 and of the retaining structure 33 between two heating mats so as to achieve a surface fusion of the plastic material of the retaining structure on the texture 32, or - laminating by means of a film of adhesive (for example polyamide), or of an adhesive deposited in powder on texture 32, with subsequent fusion of the adhesive (for example crosslinkable polyurethane) or also by dispersion of a liquid adhesive on texture 32 followed by calendering and drying. An alternative embodiment of a catalytic cartridge 30 is illustrated in FIG. 4. This alternative differs from the embodiment of FIGS. 2 and 3 in that the texture 32 made of activated carbon fibers - as well as the possible holding structure on which it is fixed - is in the form of a pleated strip arranged around the central passage 34. In the embodiment of Figures 2 and 3, a single cartridge 30 is introduced into the chamber 22. It is of course possible, as a variant, to house several cartridges simultaneously in the chamber 22 as illustrated by Figures 5 and 6. In this example, three cylindrical cartridges 30 _1f 30 ₂ , 30 ₃ are arranged side by side, these cartridges being of similar construction to that of cartridge 30. The cartridges 30 ,, 30 ₂ , 30 ₃ are fixed at their upper flanges in openings in a transverse wall 26 of the chamber 22. The outlets of the cartridges open at the upper part of the chamber 22 where the return pipe 24 opens.

Figure 7 partially illustrates another alternative embodiment of the installation of Figure 1 which differs from the latter in that the circulation loop 20 comprises several, for example two branches 28 ,, 28 ₂ connected in parallel between the pipes 22 and 24. Each branch 28 „28 ₂ comprises a chamber 22 containing one or more catalytic cartridges. Valves 29 ,, 29 ₂ mounted on the branches 28 ,, 28- make it possible to control the circulation of the reaction mixture selectively in one and / or the other of the branches.

In this way, the removal or the installation of a catalytic cartridge can be carried out in one of the chambers 22 by switching off the branch 28, or 28 ₂ which includes it, without interrupting the circulation of the reaction medium in the other branch and the entire circulation loop.

An advantage of using catalytic cartridges, in accordance with the invention, consists in the possibility of removing and replacing the catalytic charge from the installation in a very simple manner, in comparison with the prior art in which the charge is supported by grains of activated carbon dispersed within the reaction medium in the reactor vessel.

Another significant advantage lies in the absence of filtering at the outlet of the installation during the withdrawal of the desired reaction product. In addition, the embodiments described above have the additional advantage of being able to be implemented on existing installations without requiring significant modifications, in particular at the level of the reactor vessels.

The invention is however not limited to the case where the catalytic cartridge (s) are inserted in a circulation loop external to the reactor and also encompasses the case where one or more catalytic cartridges are placed in the reactor vessel itself.

Thus, in the embodiment of FIG. 8, one or more catalytic cartridges 130 are supported in the reactor vessel 110. The circulation of the reaction mixture to pass it through the catalytic cartridges is carried out by an agitator 114 mounted at the end of a rod 115. The rod 115 passes through the cover 112 of the reactor vessel and is coupled to a motor 116 driving the agitator. In another embodiment illustrated in FIG. 9, several catalytic cartridges 230 are supported in the reactor vessel 210, as in the case of FIG. 8. However, the circulation of the reaction mixture is carried out by entrainment of the latter. ci in a closed circuit comprising a circulation loop 220 external to the reactor vessel. The reaction loop 220, on which a pump 223 is mounted, connects the outlet pipe of the reactor vessel, at the bottom thereof, to a passage formed in the cover 212 of the reactor vessel. This arrangement makes it possible to optionally inject a product into the reaction mixture during its passage through the recirculation loop 220, during the treatment.

The cartridges 130 and 230 can be similar to those of FIGS. 2, 3 and 4 or have a different embodiment, but always based on the use of a coherent texture of activated carbon fibers formed inside 'a housing and supporting catalyst particles or catalytic functions.

Claims

1. Catalytic cartridge comprising a coherent two-dimensional texture (32) made of activated carbon fibers supporting catalyst particles or catalytic functions distributed over the surface of the fibers, the texture being shaped and housed inside a housing (35 ).

2. Cartridge according to claim 1, characterized in that the texture (32) is an activated carbon fabric.

3. Cartridge according to any one of claims 1 and

2, characterized in that the texture is in the form of a band wound in superimposed turns around a central passage (34).

4. Cartridge according to any one of claims 1 and 2, characterized in that the texture is in the form of a pleated strip arranged around a central passage (34).

5. Cartridge according to any one of claims 3 and 4, characterized in that the central passage is materialized by a tube (34) with porous wall closed at one end.

6. Cartridge according to any one of claims 1 to 5, characterized in that the texture (32) has at least one of its faces fixed on a porous support structure in sheet form (33).

7. Cartridge according to claim 6, characterized in that the support structure (33) is in the form of a grid.

8. Cartridge according to claim 6, characterized in that the support structure (33) is in the form of a porous membrane.

9. Industrial installation for the implementation of catalyzed chemical reaction comprising a reactor vessel (10; 110; 210) intended to receive a reaction medium and means for supporting catalyst particles or catalytic functions, characterized in that it comprises at least one catalytic cartridge (30; 130; 230) according to any one of claims 1 to 8 and means for ensuring a circulation of the reaction medium in contact with the activated carbon fiber texture contained in the cartridge.

10. Installation according to claim 9, characterized in that the cartridge (130) is disposed inside the reactor vessel (110) and the latter is provided with an agitator (114) for bringing the reaction medium into circulation.

11. Installation according to claim 9, characterized in that it comprises a circulation loop (20; 220) outside the reactor vessel (10; 210) and a pump (23; 223) for circulating the reaction medium in a closed circuit through the reactor vessel and the recirculation loop.

12. Installation according to claim 11, characterized in that the cartridge (230) is arranged inside the reactor vessel (210).

13. Installation according to claim 11, characterized in that the cartridge (30) is arranged inside a chamber (22) integrated into the recirculation loop (20).

14. Installation according to claim 13, characterized in that the circulation loop (20) has at least two branches

(28 „28 ₂ ) arranged in parallel and each comprising a chamber (22) for receiving at least one catalytic cartridge, and means (29 ,, 29 ₂ ) are provided for directing the reaction medium selectively towards one or the other room.