WO2003011458A1

WO2003011458A1 - Method for the preparation of a plurality of supported catalysts

Info

Publication number: WO2003011458A1
Application number: PCT/EP2002/008331
Authority: WO
Inventors: Peter John Van Den Brink; André Harmen SIJPKES; Bashir Husein Harji
Original assignee: Avantium International B.V.
Priority date: 2001-07-31
Filing date: 2002-07-24
Publication date: 2003-02-13

Abstract

The present invention relates to a method for the preparation of a plurality of supported catalysts, the said supported catalysts comprising an active phase on a support, in a first vessel and at least one second vessel, said vessels -being arranged in parallel, -having a first compartment comprising an inlet, -a vessel outlet, the first compartment being separated from the vessel outlet by a porous element, impermeable for the support, the method comprising the steps of: A)feeding support into the first compartment of the first and second vessels, B) feeding impregnation liquid comprising the active phase into the first compartment of the first and second vessels, under pressure conditions in the said vessels preventing passage of the impregnation liquid through the porous element, C) impregnating the support with impregnation liquid comprising contacting the support with the impregnation liquid in the first compartment of the first and second vessels, under pressure conditions in the said vessels preventing passage of the impregnation liquid through the porous element, D) removing impregnation liquid from the upstream compartment of the first and second vessels through the pores of the porous element of the said vessels in the direction of the outlet of the said vessels under pressure conditions in the said vessels allowing passage of the impregnation liquid through the porous element, leaving the supported catalyst in the first compartment of the respective first and second vessels. Further the present invention relates to an apparatus and a vessel suitable for performing the method.

Description

Method for the preparation of a plurality of supported catalysts .

The present invention relates to a method for the preparation of a plurality of supported catalysts, the said supported catalysts comprising an active phase on a support, in a first vessel and at least one second vessel, said vessels -being arranged in parallel,

-having a first compartment comprising an inlet, -a vessel outlet, the first compartment being separated from the vessel outlet by a porous element, impermeable for the support. Methods of preparing a supported catalyst in a vessel are known in the art. Generally, three different methods are used to prepare a supported catalyst, classified according to the type of impregnation used:

- 'Incipient wetness impregnation', wherein the volume of the added impregnation liquid exactly matches the pore volume of the support.

- 'Dip impregnation¹ or 'wet impregnation' wherein a surplus of liquid is added to the support and the excess is drained just after the support is completely filled with liquid. - 'Adsorption impregnation' wherein a surplus of liquid is added to the support and the excess is removed only after a relatively long time allowing for adsorption of the dissolved species .

The term "active phase" is known in the art and is understood to comprise the catalytic active components, present in the impregnation liquid, to be adsorbed or otherwise bound to the surface of the support. The active phase can be present in the impregnation liquid either as such or in the form of a precursor, that can be converted to the desired catalytically active form by e.g. oxydation (e.g. by calcination) or reduction (e.g. by hydrogenation) , as known in the art.

In the art, methods are known for the preparation of a single supported catalyst. Hereto, a certain amount of support is weighed off and transferred into a vessel. Then the support is contacted with an impregnation liquid containing an active phase by pouring the impregnation liquid into the vessel. After impregnation, the impregnated support is transferred to a filter to optionally remove excess impregnation liquid and can subsequently be dried and calcined in an oven. Moreover, the supported catalysts are mostly sticky wetted solids after impregnation, requiring laborious scraping, rendering the processes of the art difficult to automate.

US 2,898,289 e.g. describes an impregnation method in a single vessel, comprising a perforated element, impermeable for the support, but permeable for the impregnation liquid. In order to obtain effective impregnation, the vessel outlet is interconnected to a vessel inlet, enabling the impregnation liquid to circulate through the impregnation vessel. GB 1,231,934 discloses a method for the impregnation of a single porous electrode plate, by mounting the electrode plate in a receptacle and by placing a tube on the electrode plate. Subsequently, the tube is filled with an impregnation liquid that is passed through the electrode plate by the use of vacuum, applied in the receptacle.

The fact that the known methods are extremely labour- intensive, very time-consuming and involve substantial risks of contamination of the supported catalyst to be prepared, e.g. because of manual handling, a method for the simultaneous preparation of a plurality of supported catalysts has not been described. Especially in high-throughput experimentation, such as e.g. described in EP-1, 001, 846, it would be highly advantageous to prepare a plurality of supported catalysts simultaneously, e.g. to identify the most active catalyst for an envisaged chemical reaction, or to determine the optimal preparation conditions for the supported catalyst. High throughput experimentation is well known to the person skilled in the art and is used for instance in the pharmaceutical industry for the discovery and development of new and useful drugs and in the field of catalysts for the preparation and screening of new catalysts.

Therefore it is an object of the present invention to provide a method for the simultaneous preparation of a plurality of supported catalysts without the need for manual handling and wherein circulation of impregnation liquid can be avoided. Thereto, the invention provides a method for the preparation of a plurality of supported catalysts, the said supported catalysts comprising an active phase on a support, in a first vessel and at least one second vessel, said vessels

-being arranged m parallel,

-having a first compartment comprising an inlet,

-a vessel outlet, the first compartment being separated from the vessel outlet by a porous element, impermeable for the support, the method comprising the steps of:

A) feeding support into the first compartment of the first and second vessels,

B) feeding impregnation liquid comprising the active phase into the first compartment of the first and second vessels, under pressure conditions in the said vessels preventing passage of the impregnation liquid through the porous element,

C) impregnating the support with impregnation liquid comprising contacting the support with the impregnation liquid in the first compartment of the first and second vessels, under pressure conditions in the said vessels preventing passage of the impregnation liquid through the porous element,

D) removing impregnation liquid from the first compartment of the first and second vessels through the pores of the porous element of the said vessels in the direction of the outlet of the said vessels under pressure conditions in the said vessels allowing passage of the impregnation liquid through the porous element, leaving the supported catalyst in the first compartment of the respective first and second vessels. Steps A) -D) will now be explained in more detail for a single vessel. However, it is to be understood that the said steps can be conducted simultaneously in a plurality, or all, of the vessels.

The method according to the present invention is in particular suitable for impregnation methods wherein a surplus of impregnation liquid is applied, e.g. for dip impregnation and adsorption impregnation.

In step A) , the support is fed to the first compartment of the first and second vessels. As the parallel arrangement of the vessels may comprise more than only two vessels, a plurality of second vessels can be arranged in parallel with the first vessel. The support remains in the first compartment, as the vessels comprise a porous element, delimiting the first compartment and intermediate the first compartment and the vessel outlet, said porous element being impermeable for the support. The porous element can be made of any suitable material, known in the art, such as glass, quartz, metal (fibres or foam) , polymeric materials, other ceramic materials etc. As support any suitable material can be chosen. The skilled person will be aware of a suitable support material for the envisaged aim. In the art, suitable support materials are known, such as ceramic and carbon materials; also polymeric materials can be used, such as e.g. acrylic and latex materials. In step B) , the impregnation liquid is fed to the first compartment. Step B) can be performed simultaneous, before or after step A) . During step B) the pressure in the vessel is such, that the impregnation liquid is unable to pass the porous element. This can be achieved, e.g. by keeping the pressure m the first compartment of the vessel and at the outlet of the vessel (i.e. downstream of the porous element) substantially equal in combination with the proper pore diameter of the porous element. In such a case, the support allows a hydrostatic column of the impregnation liquid to be obtained when the impregnation liquid loaded on the porous element, however without the impregnation liquid passing through the said porous element at the said conditions. The skilled person will understand that the suitable pore structure, such as the pore diameter and porosity will be dependent on the impregnation liquid used, and that a suitable porous material can conveniently be determined without inventive skill. It is also possible to maintain over-pressure downstream of the porous element (i.e. at the vessel outlet), to avoid the impregnation liquid from seeping through the porous element. The skilled person will recognise that in such a case, the diameter of the pores can be larger than in the above case. In this respect it is to be noted that the porous element may be either hydrophobic or hydrophilic, depending on the nature of the impregnation liquid used. If e.g. the impregnation liquid is an aqueous solution, preferably a hydrophobic porous element, such as porous polytetrafluorethylene of a suitable pore diameter can be used, so that the liquid will not penetrate and seep through the porous element. If on the other hand, the impregnation liquid is a non-aqueous solution, the porous element is, for the same reasons, preferably hydrophilic in nature .

In step C) , the passage of the impregnation liquid is prevented in a similar or equal way, allowing interaction of the impregnation liquid with the support, i.e. for adsorption of the active phase onto the support.

In step D) , the impregnation liquid is removed from the first compartment of the vessel and thus from the support by changing the pressure conditions such, that the impregnation liquid passes through the porous element. E.g. the pressure in the first compartment can be increased, or the pressure downstream of the porous element, e.g. at the vessel outlet can be decreased, resulting in a pressure difference over the porous element. When the pressure difference is sufficient, the impregnation liquid will pass through the porous element in the direction of the vessel outlet and can e.g. be discarded. In case in step B) and/or C) an over-pressure was maintained downstream of the porous element, the said over-pressure can be removed, or be converted in an under-pressure .

Thus, without any manual handling, a supported catalyst can be prepared, using the porous element and the pressure conditions as selective element regarding the passage of the impregnation liquid.

The person skilled in the art will readily understand that the particular characteristics of the porous element and the amount of impregnation liquid used will amongst others depend on the support, impregnation liquid and conditions in the vessel to be used.

As indicated above, at least two supported catalysts can be prepared in parallel. Herewith a substantial time-saving may be obtained, and the parallel approach also facilitates to expose all samples to the same process conditions, resulting in a plurality of identical supported catalysts. As will be outlined below, any further treatment steps such as drying and calcining can be performed in the same vessel after step D) . When the vessels, or a selection of the vessels comprise identical catalysts, parallel high-throughput reactions can be performed in the same reaction vessels, wherein variable parameter (s) can be tested with the same catalyst, without the need to transfer or dose the catalyst into new reaction vessels. However, the person skilled in the art will understand that also different process conditions may be used.

The method according to the present invention is in particular useful in high throughput experimentation (or 'high speed experimentation'), for the preparation of a plurality of supported catalysts under different conditions, by changing one or more parameters in the impregnation procedure in the different vessels. Thus, a large number of (different) catalysts can be prepared simultaneously using a plurality of vessels, optionally with different impregnation conditions, such as impregnation time, temperature conditions, pH and any other conditions, known to the skilled person. Also, the ratio of impregnation liquid to support can be varied, the concentration of the active phase in the impregnation liquid, the composition of the active phase and/or the impregnation liquid, or the type of support. The skilled person will be aware of many parameters that can be varied for the preparation of a plurality of supported catalysts in order to identify and prepare the envisaged supported catalyst. Herewith, a large number of impregnation conditions and materials can be tested and be further optimised to arrive at the optimal supported catalyst for the envisaged chemical (or other) reaction.

Thereto, according to a very attractive embodiment of the method according to the invention, the plurality of supported catalysts comprises a set of supported catalysts, said supported catalysts being prepared at different conditions, comprising the steps of

-creating a set comprising a first and at least one second recipe defining parameters regarding the group, comprising the support to be fed in step A) , the impregnation liquid to be fed at step B) , and impregnation conditions of step C) or a combination of two or more thereof, the recipes of the set differing from one another regarding at least one of the parameters, and -designating a first recipe of the set to at least the first vessel, and at least one second recipe of the set to at least one second vessel, wherein step A) comprises feeding support to each vessel of the first and second vessels according to the recipe, designated to the said vessel, and step B) comprises feeding impregnation liquid to each vessel of the first and second vessels according to the recipe, designated to the said vessel, and step C) is performed in each vessel of the first and second vessels according to the impregnation parameters of the recipe, designated to the said vessel.

By creating a set of recipes that differ in one ore more parameters regarding the impregnation conditions, compounds and compositions, a collection of combinations of the said parameters is established. By assigning each of the recipes to one or more of the vessels, in the said vessels the impregnation is performed according to the recipe, assigned to the said vessel (s) . In case the set of recipes comprises more than two different recipes, the second recipes comprise a plurality of different recipes. In steps A) and B) , the support and the impregnation liquid, respectively, are fed to the respective vessels, according to the recipe assigned to the particular vessel. For example, in the first vessel, impregnation liquid can be fed having twice the concentration of the active phases as compared to the impregnation liquid, fed to one or more of the second vessels. This is also true for step C) , wherein the impregnation conditions can be varied among the vessels. This approach provides the possibility for providing a huge library of supported catalysts, the catalysts being prepared at different impregnation conditions, and/or with different supports (in composition and/ volume) and/or different impregnation liquids (in composition and/or volume) . It can even be contemplated to perform the test reactions m the same vessels, therewith avoiding any further handling of the prepared catalyst library. It is however also possible to remove the prepared catalysts from the vessels for testing in another test environment . It will be clear to the skilled person that any step or a combination thereof, or all steps of the method according to the invention can conveniently be automated with the aid of a suitable automatic control system, e.g. a microprocessor based data processing system, controlling the feeding of the amount and composition of the support, the feeding of the amount and composition of the impregnation fluid, and the impregnation conditions. Thus, at least one of the steps A), B) , C) and D) are automated. The skilled person will be able to use suitable dosing and mixing robots in combination with suitable software to design a fully automated system for the preparation of the supported catalysts according to the invention.

Preferably, in step C) the pressure in the first compartment and at the outlet of the vessel is the same, and the pore structure, such as the pore diameter and porosity, of the porous element is chosen such, that the impregnation liquid is unable to pass the said porous element at the said pressure, and wherein in step D) a pressure difference over the porous element is provided such, that the pressure in the first compartment is higher than at the outlet of the vessel, therewith allowing the impregnation liquid to pass through the porous element. As already outlined above, the impregnation step C) can advantageously be performed without a significant pressure difference over the porous element; in this situation, the hydrostatic pressure exerted by the impregnation liquid on the porous material can be neglected, as this pressure is lower than the capillary pressure required to pass the pores of the porous element. Usually, the most relevant pressures are the gas pressure in the first compartment and downstream of the porous element, e.g. at the vessel outlet. Although it is also possible to exert an over-pressure downstream of the porous element, it has been found that it is more convenient to perform step C) at equal pressures upstream and downstream of the porous element, and to remove the impregnation liquid by applying a pressure difference over the porous element, wherein the pressure in the first compartment is higher than downstream of the porous element . In a very advantageous embodiment, the said pressure difference in step D) is provided by applying an under-pressure at the location of the vessel outlet, i.e. downstream of the porous element. The vessel outlet of the vessels can conveniently be combined to a common discharge means, such as a tube, connected to the outlets of the first and one or more of the second vessels. Said common tube can e.g. be connected to a vacuum pump, so that, by activating the said vacuum pump, the impregnation liquid, present in the vessels connected to the said vacuum pump via the outlet thereof, can be simultaneously removed. However, although somewhat less preferred, a pressure pump can also be connected to the inlets of the respective vessels; this then would involve additional connections to the inlet of the vessels. Preferably, the method according to the invention comprises, after step D) and in the same vessel drying of at least one of the supported catalysts. Drying is a common step m the preparation of supported catalysts. Drying can conveniently be performed in the same vessels, wherein the impregnation has taken place, without the need for removal of the supported catalyst, which has, in this stage, the characteristics of sticky wetted solid material and is difficult to be removed from the vessel. Drying can e.g. be performed by blowing or sucking a drying fluid, such as air, through the vessel. As air can also be used to exert the over-pressure on the first compartment, step D) and this drying step can optionally be combined. Drying can also take place at elevated temperatures, by heating the respective vessel (s) .

Also, the method according to the invention preferably comprises, after step D) and in the same vessel, calcining at least one of the supported catalysts. Calcination is also a common step for the preparation of supported catalysts, and can be performed by increasing the temperature in the vessel to a suitable value, which depends on the particular supported catalyst. To remove any gaseous calcination products, a gas stream may be generated through the catalyst using similar or the same means and methods as described for the drying step. As both calcination and drying can be performed at elevated temperature, both steps can be combined. Thus according to the invention, supported catalysts can be obtained by preparation in a single vessel, including drying and calcination procedures, resulting in ready-to-use catalysts. According to the invention, also more impregnation recipes can be performed, without intermediate handling of the impregnated catalyst material. In particular, so-called sequential impregnation can be performed, by having the sequence of steps A) , B) , C) and D) followed by one or more sequences of B) , C) and D) , wherein in each subsequent impregnation sequence, different impregnation conditions can be employed. Between the said impregnation sequences, also a drying and/or calcination step can be performed. In this way a combinatorial library of catalysts can be prepared without significant manual handling of the chemist. The skilled person will understand that many possible variations in the sequential order of the said step are possible, allowing a wide range of catalyst preparation recipes using only a single vessel per catalyst.

According to a preferred embodiment of the method according to the present invention, the porous element comprises a frit.

Herewith a very easy draining through of the impregnation liquid may be achieved when applying a suitable vacuum or overpressure, while a hydrostatic column of impregnation liquid is allowed to be obtained in absence of the vacuum or over- pressure. The frit can be of any suitable material known to the skilled person, such as glass, quartz, metal (fibres or foam), polymeric materials, such as polytetrafluorethylene, or other ceramic material, etc..

It has been found that very good results are obtained when the porous element has a maximum pore diameter of at most 70 μm, preferably at most 40 μm, most preferably at most 16 μm. These pore diameters allow with increasing advantage a hydrostatic column of the impregnation liquid when the impregnation liquid is loaded on the porous element, therewith avoiding passage of the impregnation liquid through the porous material, even when the pressure in the first compartment of the vessel is substantially equal to the pressure downstream of the porous element (even when the pressure, exerted by the impregnation liquid, is not considered) . The pore diameter of the porous element preferably is between 1-70 μm, more preferably between 4-40 μm and most preferably between 10-16 μm.

It has also been found that good results were obtained when the surface of the material of the porous element shows a low affinity with the impregnation liquid. For instance, when the liquid was aqueous of nature, which often is the case, the element preferably consists of a material that has a hydrophobic character. Polymers such as polytetrafluorethylene show such behaviour. Glass and quarts shows a slight hydrophilic behaviour and as such are less preferred. However, with a proper treatment e.g. when coated with a hydrophobic coating, these materials will be as useful as polymers.

Above measures are described that will give good results to retain the liquid in step B) and C) . On the other hand such measures may work counter-effective for step D) where liquid has to be pushed through the same porous element. Here it was found that the average pore diameter of the element should not be chosen to small to allow removal of the liquid within a reasonable time period. It was found that good results were obtained when the porous element has an average pore diameter of 0.1 μm or more, preferably 1 μm or more, more preferably 4 μm or more and most preferably 10 μm or more.

The present invention further relates to an apparatus for simultaneous preparation of a plurality of supported catalysts comprising impregnation of a support with an impregnation liquid, the apparatus comprising a first vessel and at least one second vessel, the vessels being arranged in parallel, the said vessels comprising

-a first compartment having an inlet, -a vessel outlet connected to discharge means,

-first feeding means connected to the inlet of the first compartment, the first feeding means of the first vessel being free of an interconnection with the first feeding means of at least one second vessel, the first compartment and the vessel outlet of the said vessels being separated by a porous element, the discharge means of the first vessel being interconnected to the discharge means of at least one second vessel of the apparatus . The apparatus according to the present invention permits a large number of catalysts to be prepared simultaneously at different or identical conditions using a plurality of vessels, in a surprisingly simple and elegant way. Therefore, the apparatus according to the present invention is very useful in high throughput experimentation. An important aspect of the apparatus according to the present invention is that draining of the impregnated catalyst may take place without sample transfer to another vessel. Herewith a substantial timesaving may be obtained, while contamination of the supported catalyst is minimised.

The first and second vessels comprise a first compartment, connected to an inlet. The inlets of the vessels are connected to first feeding means, such as e.g. tubing, the feeding means of at least the first vessel not being interconnected to first feeding means of at least one second vessel, implicating that the material, fed through the feeding means of the said first vessel will be fed to the said first vessel, but not to the said second vessel. Via the said feeding means, e.g. a unique amount, concentration or composition of the support and/or the impregnation liquid can be fed to the first vessel, whereas to the said second vessel another amount, concentration or composition of the support and/or the impregnation liquid can be fed separately in order to provide, in a single apparatus, the possibility to produce supported catalysts under different conditions.

The first compartment of the first and second vessels are separated from the respective vessel outlets by a porous element. Said porous element is designed to avoid passage of the support, once fed into the first compartment, to the outlet. The support will remain in the first compartment and can optionally be removed therefrom. The porous element is preferably designed such, that an impregnation liquid, fed to the first compartment, can pass the porous element in a pressure dependent manner, e.g. by applying a pressure difference over the porous element, as explained above.

The outlets of the first and second vessels are connected to discharge means, such as tubing. The discharge means of the first vessel is interconnected to the discharge means of at least one second vessel, therewith enabling simultaneous removal of impregnation liquid of the vessels of which the discharge means are interconnected. The term "interconnected" herein means that preferably, free communication between the interconnected objects is possible, e.g. without the interference of a flow restrictor or shut-off valve.

It is to be noted that the porous element can be located at the vessel outlet; however, it is also possible that the porous element is located in the vessel at a distance of the outlet, therewith defining a second compartment, downstream of the porous element. The terms "upstream" and "downstream" refer herein to the directions, seen from the porous element, to the vessel inlet and the vessel outlet, respectively.

As such, apparatuses for the preparation of a single supported catalyst by impregnation are known from e.g. US 2,898,289 and GB 1,231,934, as discussed above.

Further, apparatuses for high-throughput experimentation are known, comprising multiple vessels, arranged in parallel, see e.g. EP-1, 001, 846, EP-0, 971,225 and WO98/39099 However, the said apparatuses are designed for testing a plurality of compounds under different or identical reaction conditions, and are not suitable for the preparation of multiple supported catalysts according to the invention. The arrangements of the feeding and discharge means of the known apparatuses are arranged in a different manner, e.g. the feeding means of the apparatus of EP-0,971,225 are combined for all the vessels, whereas the discharge means of the apparatus of WO98/39099 are not interconnected to one another in order to enable, for each vessel separately, analysis of the reactants, discharged from the vessel outlets.

Preferably, the vessel outlet of at least one of the first and second vessels are free of an interconnection with the vessel inlet of the said vessel, as any recirculation of impregnation liquid is not necessary. More preferably, the vessel outlets of the first and second vessels are free of any interconnection with the vessel inlet of any vessel of the apparatus. As indicated above, in the apparatus of US 2,898,289 the vessel outlet is interconnected to a vessel inlet, in order to enable recirculation of impregnation liquid. In another preferred embodiment, the apparatus comprises a plurality of second vessels, the first feeding means of at least one of the said second vessels being free of an interconnection with the first feeding means of any additional second vessel. In this embodiment, also at least one second vessel has a first feeding means, not interconnected to feeding means of another vessel of the apparatus. Thus, both the first and at least one second vessel have separate feeding means for unique delivery of support and/or impregnation liquid. Most preferably, the first feeding means of the first and second vessels are free of an interconnection to one another, implying that to each of the first and second vessels support and/or impregnation liquid can be delivered through separate, not interconnected feeding means, so that to each of the said vessels delivery can take place in a unique manner.

The first compartment of the first and second vessels preferably comprise a second feeding means, the second feeding means of the first and second vessels being interconnected to one another. By these second feeding means, compounds and compositions can be delivered to 'the vessels, connected to the said second feeding means. This advantageous e.g. when to the vessels the same support is to be delivered; said support can be fed through the second feeding means. The first feeding means can e.g. be used for delivery of e.g. different impregnation liquids to the vessels, as indicated above. Of course will it also be possible to deliver the impregnation liquid through the second feeding means, and the support (s) through the first feeding means. The second feeding means can also be used to blow a gas, such as air through the vessels, e.g. to apply a pressure on the first compartments of the vessels, and/or to dry the supported catalysts after impregnation.

Preferably, the apparatus according to the invention comprises a pressure regulator for simultaneously applying a pressure difference between the first compartment and the outlet of the first and at least one second vessel so as to selectively prevent or allow pressure dependent passage from the impregnation fluid in the first and second vessel from the respective first compartment in the direction of the respective outlet through the respective porous element. In case the apparatus comprises a plurality of second vessels, the pressure regulator is preferably connected to a plurality of the said second vessels, most preferably to all of the said vessels, enabling simultaneous removal of the impregnation liquid from the vessels by applying a pressure difference over the porous element, as explained above. The pressure regulator can be connected to the first compartments of the vessels, e.g. via the second feeding means, to exert an over-pressure on the said first compartments. However, it is preferred that the pressure regulator comprises a vacuum pump, connected to the discharge means of the first and second vessels of the apparatus, so that the impregnation liquid is removed from the first compartment of the vessels by an under-pressure.

The pressure regulator is preferably controlled by controlling means for keeping the pressure difference between the first compartment and the vessel outlet of the first and second vessels at a predetermined value preventing pressure dependent passage of the impregnation liquid through the porous element during a first time period, and for changing the said pressure difference to a predetermined second value allowing the pressure dependent passage of the impregnation liquid through the porous element during a second time period. The controlling means can e.g. comprise a data processing system, sending a signal to the pressure regulator after the first time period, resulting in the pressure change by e.g. switching on or off of the pressure regulator. After the second time period, a second signal is sent to the pressure regulator, switching the pressure regulator off or on, respectively. The pressure regulator can however also be controlled by switching the regulator on and off manually. The time periods can be varied if required. During the first time period, the impregnation liquid is held in the first compartment, so that impregnation of the support can take place, whereas during the second time period, the pressure difference is such, that the impregnation liquid is removed from the first compartment, through the porous element in the direction of the vessel outlet. During the impregnation step, i.e. the first time period, the first value of the pressure difference can be zero; in that case, during the second time period, an over-pressure is applied in the first compartment or an under-pressure downstream of the porous element. As indicated above, it is also possible to apply an over-pressure downstream of the porous element during the first time period, in order to prevent the impregnation liquid from seeping through the porous element. Preferably, the porous element of at least one of the first and second vessels of the apparatus comprises a frit.

The porous element preferably has a pore diameter of at most 70μm, preferably at most 40μm and most preferably of 16 μm. The average pore diameter is preferably at least O.lμm, more preferably at least 1 μm, more preferably 4 μm and most preferably at least 10 μm. The porous element preferably has a pore diameter of 1-70 μm, more preferably of 4-40 μm, most preferably of 10-16 μm.

The invention also relates to an assembly of a first and at least a second apparatus according to the invention, wherein the vessel outlets of the vessels of the first apparatus are interconnected to a common first discharge means, and the vessel outlets of the second apparatus are interconnected to a common second discharge means, the first and second discharge means each comprising a valve, the first and second discharge means being connected to a vacuum pump. This arrangement allows an even more versatile preparation of supported catalysts according to the invention, in that the impregnation liquid of the vessels of a single apparatus can be removed simultaneously, whereas the impregnation liquid of the vessels of the second apparatus remain in the respective first compartments. Thus, an elegant way to vary the impregnation time (i.e. the residence time of the impregnation liquid in the first compartments) is offered. Finally, the present invention relates to a vessel as described in the apparatus according to the present invention, in particular having a porous element having a pore diameter of 10-16 μm, the porous element preferably comprising a frit.

Hereinafter the present invention will be illustrated in more detail by the following drawings, wherein: Figure 1 shows a schematic cross-sectional view of the apparatus according to the present invention, comprising a supported catalyst preparing assembly,

Figure 2 shows a schematic cross-sectional view of an apparatus according to the present invention, and Figure 3 shows a schematical cross-section of an assembly of six apparatuses according to the invention through the first compartments of the vessels.

In the figures, the same reference numbers are used for the same or similar features.

In figure 1 a schematic cross-sectional view of the apparatus according to the present invention is shown. The apparatus comprises a first (e.g. quartz) vessel 1 and a plurality of vessels 2, each of the vessels having a vessel inlet 3 and a vessel outlet 4. Each vessel 1,2 contains a porous element 5, such as a frit. Between the frit 5 and the vessel inlet, the vessel comprises a first compartment 10. Between the frit 5 and the vessel outlet 4, the vessel comprises a second compartment 11. However, the frit may also be located at the vessel outlet, therewith minimising the volume of the second compartment; the vessel may also be free of a second compartment .

To each of the vessels, first feeding means 7 for delivery of support and/or impregnation liquid are connected, the said first feeding means not being connected to feeding means of another vessel in the apparatus. The vessels are further connected to second feeding means 6 for feeding support or impregnation liquid into the vessel 2 through the vessel inlet 3. However, second feeding means may not be present; in that case, both the support and the impregnation liquid can be delivered to the vessels by the first feeding means 7, or by multiple feeding means 7, each connected to a vessel inlet. As support, any kind of support may be used, such as granules, powder, a monolith, porous foam, etc. In the shown embodiment the second feeding means 6 of each vessel are interconnected. The second feeding means 6 may also be designed to supply an inert gas or air through the vessel inlet 3. In that case, the said second feeding means may also be designed to deliver support and/or impregnation liquid, whereas it is also possible that both the support and the impregnation liquid are delivered by first feeding means. Also, separate feeding means for the gas may instead be provided.

The vessel outlets 4 are connected to discharge tubes 12, which tube are interconnected via a manifold 9. Manifold 9 is connected to a vacuum pump 8. The apparatus may further e.g. comprise (not shown) heating means.

In figure 2 a rack 18, comprising a perforated top plate 16 and a perforated lower plate 17, for holding several rows of six vessels 1,2 (e.g. having an outer diameter of 30 mm, inner diameter of 25 mm, length of 150 mm) according to the present invention is shown. The rack 18 is placed on a vacuum plate 19 comprising discharge channel 20 connecting the vessel outlets 4 with a vacuum pump (not shown) . The vacuum plate 19 further contains recesses 13 wherein O-rings 14 are provided. The outlets 4 of the vessels 2 rest on these O-rings 14. In the shown embodiment, the vessels 2 comprise a flange 15 near the inlets 3.

In figure 3 a first apparatus 21 and five second apparatuses 22A-E are arranged in a vacuum plate 19. Each apparatus comprises a first vessel 1, and three second vessels 2. Each vessel comprises a frit, only shown in two of the vessels for clarity reasons. The vessel outlets of each apparatus 21 and 22 are connected to a common discharge channel 20. The discharge channels 20 are provided with a valve 23 for closing off the discharge channel of a single apparatus, and connected to a manifold 9. Manifold 9 is connected, via tubing 24 to a vacuum pump 8.

In use of the apparatus according to figure 1, which may of course contain several other components, a support is fed e.g. by second feeding means 6 into the vessel 2 through the vessel inlet 3. Hereby the support is placed on top of the frit 5. Then the support is contacted with an impregnation liquid supplied by the first feeding means 7. However, it is also possible that the support is fed by the first feeding means and the impregnation liquid by the second feeding means. After a predetermined time period, excess impregnation liquid is removed by applying a vacuum at the outlet 4 of the vessel 2 by using the vacuum pump 8 and manifold 9. Suitably, a sealing element such as an O-ring (figure 2) may surround the opening of outlet 4 such as to provide an airtight sealing when a vacuum is applied. Subsequently, the impregnated support on the frit 5 is dried by supplying air or an inert gas through the first feeding means 6. Instead a vacuum may be applied. Then, the dried impregnated support obtained on the frit 5 is further dried by elevating the temperature to a suitable range using (not shown) heating means. To this end e.g. hot air may be blown along the vessels, or the vessels may be placed in an oven. Thereafter, the supported catalyst is calcined using the same or other heating means. Finally, the obtained supported catalyst can be collected and/or transferred to e.g. an apparatus for screening catalysts. For collection of the obtained support catalyst special means may be provided, or the vessels may be easily accessible. However, any further reaction, such as a screening reaction can be carried out in the same vessels, i.e. without the need to remove the supported catalyst.

The persons skilled in the art will readily understand that many modifications can be made. For instance, the heating and calcining of the support may take place in the apparatus as such, or the vessels 2 may be collected in a rack and transferred to an oven as is illustrated in figure 2.

Also the vessels 2 may be configured such that they extend horizontally, i.e. the inlets 3 and outlets 4 of the vessels 2 are in the same horizontal plane.

In use of the rack 10, a support is (e.g. manually) fed into the vessel inlet 3 of the vessels 1,2. Then the support is contacted with an impregnation liquid which is also fed through the vessel inlet 3. After a while, excess impregnation liquid is removed through the frit 5 by applying a vacuum at the outlet 4 using the vacuum plate 11 and the (not-shown) vacuum pump. The O-rings 14 provide for a airtight sealing of the outlets 4.

Then, the rack 10 holding the vessels 1,2 is removed from the vacuum plate 11 by lifting. The flanges 15 of the vessels 1,2 will then rest on the top plate 16.

Subsequently, the rack 10 may be transferred to an oven (not shown) for drying and/or calcining of the supported catalyst contained in the vessels 1,2, or suitable heating means may be present in the apparatus. The assembly of apparatuses as shown in figure 3 can be used e.g. for varying the impregnation time between the apparatuses. In case different impregnation times are to be tested, e.g. the impregnation liquid is removed from the vessels 1 of the first apparatus 21 by opening valve 23, connected to the discharge channel 20 of apparatus 21 and by applying vacuum by the vacuum pump 8. The valves of the second apparatuses 22A-E remain closed, so that any impregnation liquid present in the vessels of the second apparatuses remain in the first compartment of the said vessels. In a subsequent step, the valve 23 of apparatus 22A is opened, so that the impregnation liquid is removed from the vessels of the said second apparatus 22A. Accordingly, the impregnation liquid from the vessels of the further second apparatuses 22B-E can be removed by opening the corresponding valves at the desired time point. Within the different vessels of each apparatus, different impregnation conditions or materials can be used, as explained above.

As will be clear from the above, the method and apparatus according to the present invention permit several supported catalysts to be prepared simultaneously while contamination of the supported catalysts is not likely to occur or at least minimized.

Claims

C L A I M S

1. Method for the preparation of a plurality of supported catalysts, the said supported catalysts comprising an active phase on a support, in a first vessel and at least one second vessel, said vessels: -being arranged in parallel,

-having a first compartment comprising an inlet,

-having a vessel outlet, the first compartment being separated from the vessel outlet by a porous element, impermeable for the support, the method comprising the steps of:

A) feeding support into the first compartment of the first and second vessels,

D) removing impregnation liquid from the first compartment of the first and second vessels through the pores of the porous element of the said vessels in the direction of the outlet of the said vessels under pressure conditions in the said vessels allowing passage of the impregnation liquid through the porous element, leaving the supported catalyst m the first compartment of the respective first and second vessels.

2. Method according to claim 1, wherein the plurality of supported catalysts comprises a set of supported catalysts, said supported catalysts being prepared at different conditions, comprising the steps of

-creating a set comprising a first and at least one second recipe defining parameters regarding the group, comprising the support to be fed in step A) , the impregnation liquid to be fed at step B) , and impregnation conditions of step C) or a combination of two or more thereof, the recipes of the set differing from one another regarding at least one of the parameters, and

-designating a first recipe of the set to at least the first vessel, and at least one second recipe of the set to at least one second vessel, wherein step A) comprises feeding support to each vessel of the first and second vessels according to the recipe, designated to the said vessel, and step B) comprises feeding impregnation liquid to each vessel of the first and second vessels according to the recipe, designated to the said vessel, and step C) is performed in each vessel of the first and second vessels according to the impregnation parameters of the recipe, designated to the said vessel.

3. Method according to claim 1 or 2, wherein in step C) the pressure in the first compartment and at the outlet of the vessel is the same, and wherein the pore structure of the porous element is chosen such, that the impregnation liquid is unable to pass the said porous element at the said pressure, and wherein in step D) a pressure difference over the porous element is provided such, that the pressure in the first compartment is higher than at the outlet of the vessel, therewith allowing the impregnation liquid to pass through the porous element.

4. Method according to claim 3, wherein the pressure difference is provided by applying an under-pressure at the location of the outlet.

5. Method according to any of the preceding claims, comprising, after step D) and in the same vessel, drying of at least one of the supported catalysts.

6. Method according to any of the preceding claims, comprising, after step D) and in the same vessel, calcining at least one of the supported catalysts.

7. Method according to any of the preceding claims, comprising, after step D) the step of collecting the supported catalysts from the first vessel and at least one second vessel.

8. Method according to any of the preceding claims, wherein the porous element comprises a frit.

9. Method according to any of the preceding claims, wherein the porous element has a pore diameter of at most 70 μm, preferably at most 40 μm, most preferably at most 16 μm.

10. Method according to any of the preceding claims, wherein the porous element has an average pore diameter of at least 0.1 μm, preferably at least 1 μm, more preferably at least 4 μm, most preferably at least 10 μm.

11. Method according to any of the preceding claims, wherein the porous element has a pore diameter of 10-16 μm.

12. Method according to any of the preceding claims, wherein at least one of the steps A) , B) , C) and D) are automated.

13. Apparatus for simultaneous preparation of a plurality of supported catalysts comprising impregnation of a support with an impregnation liquid, the apparatus comprising a first vessel and at least one second vessel, the vessels being arranged in parallel, the said vessels comprising

-first feeding means connected to the inlet of the first compartment, the first feeding means of the first vessel being free of an interconnection with the first feeding means of at least one second vessel, the first compartment and the vessel outlet of the said vessels being separated by a porous element, the discharge means of the first vessel being interconnected to the discharge means of at least one second vessel of the apparatus .

14. Apparatus according to claim 13, wherein the vessel outlet of at least one of the first and second vessels are free of an interconnection with the vessel inlet of the said vessel.

15. Apparatus according to claim 13 or 14, wherein the apparatus comprises a plurality of second vessels, the first feeding means of at least one of the said second vessels being free of an interconnection with the first feeding means of any additional second vessel.

16. Apparatus according to claim any of the claims 13-15, wherein the first feeding means of the first and second vessels are free of an interconnection to one another.

17. Apparatus according to claim any of the claims 13-16, wherein the first compartment of the first and second vessels comprise a second feeding means, the second feeding means of the first and second vessels being interconnected to one another.

18. Apparatus according to claim any of the claims 13-17, wherein the apparatus comprises a pressure regulator for simultaneously applying a pressure difference between the first compartment and the outlet of the first and at least one second vessel so as to selectively prevent or allow pressure dependent passage from the impregnation fluid in the first and second vessel from the respective first compartment in the direction of the respective outlet through the respective porous element.

19. Apparatus according to claim 18, wherein the pressure regulator comprises a vacuum pump, connected to the discharge means of the first and second vessels of the apparatus.

20. Apparatus according to claim 18 or 19, wherein the pressure regulator is controlled by controlling means for keeping the pressure difference between the first compartment and the vessel outlet of the first and second vessels at a predetermined value preventing pressure dependent passage of the impregnation liquid through the porous element during a first time period, and for changing the said pressure difference to a predetermined second value allowing the pressure dependent passage of the impregnation liquid through the porous element during a second time period.

21. Apparatus according to any of the claims 13-20, wherein the porous element of at least one of the first and second vessels comprises a frit.

22. Apparatus according to any of the claims 13-21, wherein porous element has a pore diameter of at most 70 μm, preferably at most 40 μm, most preferably at most 16 μm.

23. Apparatus according to any of the claims 13-22, wherein the porous element has an average pore diameter of at least 0.1 μm, preferably at least 1 μm, more preferably at least 4 μm, most preferably at least 10 μm.

24. Apparatus according to any of the claims 13-23, wherein the porous element has a pore diameter of 10-16 μm.

25. Apparatus according to any of the claims 13 -24, wherein the porous element is hydrophobic.

26. Assembly of a first and at least a second apparatus according to any of the claims 13-25, wherein the vessel outlets of the vessels of the first apparatus are interconnected to a common first discharge means, and the vessel outlets of the second apparatus are interconnected to a common second discharge means, the first and second discharge means each comprising a valve, the first and second discharge means being connected to a vacuum pump.

27. Vessel as described in the apparatus according to any of the preceding claims 13-26.