The method of preparation of the catalyst or catalyst precursor, catalyst and method for partial oxidation of hydrocarbons with its use

 

(57) Abstract:

Describes a method of obtaining a ceramic foam, bearing one or more catalytically active components or their precursors, and the component is active in a form different from the inorganic oxide comprising the impregnated foam sealing phase containing a catalytically active component or its precursor, and drying, where the drying carried out without significant pre-drainage impregnating phase of the ceramic foam and where the catalytically active component or its precursor is present throughout the method in one or more forms that are different from their inorganic oxide. The method differs in that the impregnating phase has a viscosity of more than 1 SP. Thus obtained ceramic foams find application in catalytic reactions, in particular for the catalytic partial oxidation of hydrocarbons. Describes the method of partial oxidation of hydrocarbons with its use. 3 S. and 7 C. p. F.-ly.

The present invention relates to a method for producing ceramic foams, bearing one or more catalytically active components and/or the bearing catalytically active components or precursors for use in the processing of gases and as catalysts in reactions catalytic reactions, especially when getting monoxide and hydrogen by partial oxidation of hydrocarbons, in the processes of reduction of nitrogen oxides, oxidation of ethylene, etc.

It is known that ceramic foams are used in various fields, in particular relatively recently began to use them as carriers for catalytically active materials that meet several requirements, as described in the work of M. V. Twigg and J. T. Richardson, "preparation and properties of ceramic foam carrier catalysts", published in proceedings of the 6th International Symposium "Scientific Bases for the preparation of heterogeneous catalysts", 5-8 September 1994, Louvain-la-Neuve, Belgium). Ceramic foam with open pores and a more traditional extrudates can be obtained from materials having high thermal resistance; they contribute to the catalytic reaction on the surface due to the meandering flow pattern, the pins by connecting neighboring pores or "cells" that provide non-linear channels, and layers of extrudates through a disordered packing of particles. Ceramic foam ensuring the passage of gases at high space velocities and acceptable pressure drop; they are easily molded and obespeche use in the conversion of steam to methane, includes mesh asymmetric channels passing through the foam containing the catalytically active material on the carrier and stabilizer is an inorganic oxide to prevent sintering of the active material. The stabilizer and the active material is introduced by impregnation of the foam by immersing the foam in an aqueous salt solution of the stabilizer and the active component, drain to remove excess solution and annealing at 450oC. This process is repeated so that the foam formed a sufficient layer of impregnating substances. Described foam can be used at relatively low temperatures of about 760oC.

In the French patent FR 2590887 disclosed oxides of zirconium, having a stable surface area at elevated temperatures, oxides contain additives as silicon oxides, rare earth elements, yttrium, cerium and/or aluminum. This Supplement can be administered in a number of ways, including coprecipitation, mixing salt hydrate Sol and the impregnation of the oxide of zirconium salt precursor additives. Preferably the impregnation is carried out "dry" method, whereby the total amount of impregnating solution is approximately equal to the total volume of pores (oxide) media. In the curve at 160oC for 16 hours and calcined at 400oC. there are No references to the media with foamy structure comprising pores of the same order of magnitude or higher than the mesoporous structure, which assumes a different mechanism causing additives.

Providing a ceramic foams containing a significant amount (load) of inorganic oxides, saves the problem, even more, in applications that use strict conditions that are typical for some of the processes for which you want to save the enhanced surface area in comparison with the known foam media.

Currently, it has been unexpectedly found that the restriction on the loading of the inorganic oxide and the surface area is not the intent of the additional layer, as is known from the publications referred to, and how to ensure, in consequence of which was not reached full advantage.

The application for the European patent N 94 203453.9 dedicated to the unexpected discovery that a specific method of obtaining ceramic pins, bearing inorganic oxide(s), you can achieve a significant increase in the amount (load) of the inorganic oxide and the square is avce in the European patent N 94 203453.9, includes the impregnation of the foam insulating phase containing inorganic oxide(s) in the insulating phase, and drying; in this way a sealing phase has a viscosity of more than 1 SP, that is greater than the viscosity of water, and drying carried out without significant pre-drainage (draining) impregnating phase of the ceramic foam.

Unexpectedly, at present, it was found that the method disclosed in the application for the European patent N 94 203453.9 for ceramic pins, bearing one or more inorganic oxides, can also be used to obtain ceramic pins, bearing one or more catalytically active components, which are fully or partially active form different from inorganic oxides.

Accordingly, the present invention proposes a method of obtaining a ceramic foam, bearing one or more catalytically active components or their precursors which are active in the state distinguished from inorganic oxides; this method involves the impregnation of the foam insulating phase containing a catalytically active component or its precursor, and drying and impregnating phase has a viscosity of more than 1 SP grooves of the ceramic foam, and a catalytically active component or its precursor is present in one or more forms, differing from its inorganic oxide, throughout the process.

The hallmark of the invention is that the application of the impregnating phase with a viscosity greater than that of water provides a significant holding impregnating phase in the pores of the foam before and during drying. This problem is not met when the impregnation of other materials having the order of magnitude of pore size smaller than what is usually found in ceramic foams.

Suitable impregnating phase has a viscosity of more than 1 SP, preferably 1 CPS (at 20oC, preferably from 5 to 80 JV, more preferably from 7 to 50 JV. A suitable viscosity can be selected in accordance with properties of ceramic foam, in particular of pore sizes, with a smaller pore size will be required impregnating phase with lower viscosity. The treatment is conveniently carried out at a temperature of between 0 and 90oC, especially from 10 to 50oC, more specifically at 20oC.

It is convenient to carry out the drying without significant pre-drainage (draining) impregnating phase of the ceramic foam. The link in the OECS wet coating method and impregnation, which may include a vacuum foam, centrifugation or blowing air through the foam, for example. It is assumed that any introduced into the pores of the foam insulating phase is essentially not it should be removed, rather it is to hold due to its viscosity. Therefore, it is convenient to any drainage impregnating phase from the pores of the foam before drying was less than 60%, preferably less than 50%, more preferably from 0 to 40%, more preferably 0-20% of the administered amount. Preferably the pores of the foam is essentially filled with impregnating phase before drying. Preferably the pores of the foam are filled by at least 60% of the impregnating phase, more preferably at least 85%. Convenient to ceramic foam slowly or gradually immersed in the impregnating phase, whereby to prevent the formation of air pockets and ensures that the pores are filled. The sink rate or degree of immersion can be defined in accordance with the pore size (ppi - number of pores per 1 inch) foam and viscosity of the impregnating phase.

The impregnation can be carried out at atmospheric pressure or below atmospheric pressure. When using a pen with a small diameter can be calculated, for example, on the basis of density, weight and size of the foam, resulting in possible to determine the required number of insulating phase.

However, there is a possibility provided in an additional aspect of the invention is to provide a course of special eviction impregnating phase and/or a catalytically active component or its precursor, and thereby to ensure the development of the gradient of the impregnating substance. This gives the advantage of providing a gradient in the loading of solid substances, which cannot be obtained in alternative ways. This can be achieved, for example, by selecting the impregnating phase with a slightly lower viscosity than the viscosity, which in other case would be appropriate for this sample of foam. Mentioned here, the term "gradient" for any given property, the samples of the foam of the invention relates to a stepped or continuous change in the value characterizing this property, such as loading of solids, for example, across a given size impregnated foam sample.

Ceramic foam is used as a carrier for one or more catalytically active components. In this regard, the term "catalytically active component" in sa the catalytic activity, together with other components, which, acting as promoters, stabilizers, etc., that have a beneficial effect on the catalytic properties of the components present.

Applied to the ceramic foam catalytically active component can be selected from any suitable component or combination of components known from the prior art. Suitable catalytically active components include the elements of groups IA, IIA, IIIA and IVA of the Periodic table of elements and transition metals. Preferred catalytically active components are elements selected from groups IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VB, VIB, VIIB, VIII and the lanthanides. Made here references to the Periodic table of elements relate to the version of the CAS, which was published in the CRC Handbook of chemistry and physics, 68th edition. Preferred elements include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, scandium, yttrium, lanthanum, cerium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, manganese, iron, ruthenium, osmium, cobalt, rhodium, iridium, Nickel, palladium, platinum, copper, silver, gold, zinc, cadmium, mercury, aluminum, gallium, silicon, germanium, tin and lead. The choice of catalytically act is finally obtained ceramic foam.

One of the processes, which are particularly suitable ceramic foam obtained by the method of the present invention is a catalytic partial oxidation of hydrocarbons. Suitable catalytically active components for the catalytic partial oxidation process are the elements of group VIII: cobalt, iron, Nickel, ruthenium, palladium, osmium, rhodium, iridium and platinum. The preferred elements for the catalytic partial oxidation process are ruthenium, rhodium and iridium. Additional use of ceramic foam are in the process of reduction of nitrogen oxides. Suitable catalytically active components for the reduction of nitrogen oxides include vanadium, titanium and mixtures thereof. Ceramic foam obtained by the method of the present invention are also suitable for use in the production of ethylene oxide. The most suitable catalytically active component for this application is silver.

The catalytically active components can be provided on the ceramic foam directly in an element or in the form of his predecessor. Suitable precursors are salts and complexes of the catalytically active componentone are preferred. In General, if you apply the precursor of the catalytically active component, it is preferable that the precursor does not contain elements or components that will impair the characteristics of ceramic foams at their intended end use. Alternatively, the precursor can be chosen so that they contain items that can be removed during subsequent processing of ceramic foam, such as annealing, before applying the foam. Suitable inorganic precursors of the catalytically active components include the halides, in particular chlorides, bromides and iodides, nitrates, sulfates, phosphates. Suitable organic precursors include CARBONYLS, acetates, acetylacetonates and oxalates.

Ceramic foam is impregnated with the catalytically active component or its precursor, using a sealing phase. Impregnating phase may be in the form of any suitable liquid having a viscosity greater than water. Convenient to impregnating phase was in the form of an aqueous or organic solution, suspension, Sol, gel, slurry or dispersion. The receipt of such impregnating phase is well known in the prior art.

the example in the form of a slurry or suspension, it is possible to use any desired solids content. Preferably used in such cases impregnating phase has a solids content greater than 0.01 wt.%, whereby the pores is introduced sufficient amount of catalytically active component or precursor. Preferably the solids content is between 0.01 and 20 weight. % and a maximum loading of solids depends on the load at which deteriorates the dispersion of particles or flocculation occurs.

The catalytically active component or a combination thereof may be present in the final product in any suitable amount, to perform the desired function. Typically, the catalytically active component is present in an amount of more than 0.01 wt.% from the weight of the ceramic foam, more preferably from 0.01 to 20 wt.%.

The foam can be pre-processed prior to treatment in order to improve the dispersion and cohesion possible catalytically active component. It was found that pre-treatment of the foam with water and drying to obtain the optimal concentration of surface hydroxide groups, such as the impregnation of p is dried. As noted above, an important part of the method of the present invention is that the drying carried out without significant pre-drainage (draining) impregnating phase of the ceramic foam. Drying can be accomplished in any known manner, such as exposure to a current of air at ambient temperature, drying in the oven or microwave drying. Any undesired displacement of impregnating phase during drying can be conveniently prevented by rotation of foam or other suitable means.

The conditions under which the dried ceramic foam will depend mainly on used concrete sealing phase. Typically, the drying is carried out at temperatures in the range from ambient temperature to 100oC.

After drying the ceramic foam can be ignited. The annealing can be performed by heating the ceramic foam to a temperature in the range from 100 to 1200oC. Usually, the procedure of roasting lasts from 2 to 8 hours. If annealing is carried out, it should be conducted in an inert or reducing atmosphere, in order to avoid the formation of oxide forms a catalytically active the foam can be impregnated with more than one catalytically active component or its predecessor, simultaneously or sequentially. If you will use a sequential impregnation, it may be advantageous to complete the impregnation, drying and calcination for each component before proceeding to the impregnation of the next component. Similarly, if you want to spend a few impregnation of the ceramic foam, in order to achieve a higher loading of the catalytically active component or precursor, it may be preferable to carry out the stage of drying and calcination after each impregnation stage.

Suitable ceramic foam, which can be used in the present invention are, for example, those who have 5, 10 or better more then 1 inch (2.54 cm). Usually available industrial foams are in the range up to 200 pores per inch (2.54 cm). Preferably, the number of pores in the foam is in the range from 10 to 60 pores per inch (2.54 cm), more preferably from 15 to 40 long by 2.54 see the Choice of foam will generally depend on the intended application, whereby the choice of material of high-temperature stable individual or mixed refractory oxides of silicon, aluminum, titanium, zirconium and their (partial) stable is lnost, resistance to thermal shock and/or strength, and thereby the increase in the content of pores per unit length generally corresponds to an increase of sinuosity of the fluid passing through the foam. In specific application areas, for example, when the desired contact surface of the pores with the liquid flowing high bulk velocities through the foam, there is a need in the foam with high tortuosity. The term "tortuosity" is a General term, which, if it belongs to the fixed layer of the catalyst, can be defined as the ratio of the length of the path for gas passing through the layer to the length of the shortest straight line path through the layer. Thus, neizvesty layer, such as a cell of the monolithic structure has a tortuosity of 1.0. Convenient to the ceramic foam of the present invention had a tortuosity of at least 1,1, such as from 1.1 to 10.0, more preferably from 1.1 to 5.0, most preferably from 1.3 to 4.0.

A particular advantage of the present invention is that the method essentially does not depend on the size, shape or other parameters of the sample impregnated foam. Convenient that it is possible to impregnate the foam of any size or scale, and to obtain excellent results, nepremicnine from 0.5 cm to 1 m

In an additional aspect, the present invention provides the use of ceramic foams obtained, as defined above, as a catalyst in the catalytic conversion process. Special advantages are obtained when using ceramic foams obtained as described above as a catalyst in the conversion process, which uses a temperature greater than or equal to 800oC, are preferably used in flow rate greater than or equal to 500000 normal liters/kg/HR, more preferably in the method of producing carbon monoxide and hydrogen by partial oxidation of hydrocarbons.

In an additional aspect, the present invention provides a method for partial oxidation of hydrocarbons, which comprises contacting the hydrocarbon and oxygen-containing gas with a catalyst containing a catalytically active component element from group VIII of the Periodic table, the catalyst is in the form of a ceramic foam obtained by the method described above.

Further, the invention is illustrated with the help of non-limiting examples.

EXAMPLE

Rectangular samples (approximately HK cm) the East rhodium (3) (3,05 g of RhCl3in 21,45 ml, a viscosity of less than 1 CPS (at 20oC) and by impregnation of the foam with the same solution of rhodium, but containing hydroxyethyl cellulose (0.5 g, the viscosity of between 50 and 150 CPS (at 20oC, FLUKA 54290 environments. the viscosity). The impregnated foam is carried out by immersing the foam in an aqueous solution, followed by application of vacuum (0.8 bar, 80 kPa), for 1.5 hours, the Samples are transferred into a drying Cabinet, essentially without loss of sealing medium from the pores, and then dried and 120oC for 4 h After drying the samples calcined at 700oC 4 hours. Foam weighed before modification and after drying and calcination. In the example, which was used for impregnating Sol of low viscosity, receive calcined foam containing 1.1 wt.% rhodium (calculation based on the assumption that the rhodium is present in the form Rh2O3). In the example, which was used for impregnating Sol high viscosity receive calcined foam containing 5.6 wt.% rhodium. In both samples the rhodium is present mainly in the form of a metallic rhodium.

1. Method of manufacturing ceramic foam carrying one or more catalytically active components or their precursors, and the component is active in a form different from mponent or its predecessor, and drying, where the drying carried out without significant pre-drainage impregnating phase of the ceramic foam and where the catalytically active component or its precursor is present throughout the method in one or more forms that are different from their inorganic oxide, characterized in that the impregnating phase has a viscosity of more than 1 SP.

2. The method according to p. 1, characterized in that the impregnating phase has a viscosity of 1 CPS (at 20C.

3. The method according to p. 1 or 2, characterized in that the impregnating phase has a viscosity of from 5 to 80 SP.

4. The method according to any of paragraphs.1-3, characterized in that the outlet sealing phase of the foam before drying is from 0 to 40% of the administered amount.

5. The method according to any of paragraphs.1-4, characterized in that the pores of the foam, essentially, filled with impregnating phase before drying, preferably filled with insulating phase by at least 60%, more preferably at least 85%.

6. The method according to any of paragraphs.1-5, characterized in that the catalytically active component selected from cobalt, iron, Nickel, ruthenium, osmium, rhodium, iridium, platinum, vanadium, titanium, silver, palladium or mixtures thereof.

7. The way p the th selected from chlorides, bromides, iodides, nitrates, sulfates and phosphates.

8. The method according to any of paragraphs.1-7, characterized in that the ceramic foam has a higher tortuosity in the range from 1.1 to 5.0.

9. Ceramic foam obtained by the method according to any of paragraphs.1-8, is used as the catalyst in the catalytic conversion process, in particular in the method of producing carbon monoxide and hydrogen by partial oxidation of hydrocarbons.

10. The method of partial oxidation of hydrocarbons comprising contacting a hydrocarbon feedstock and oxygen-containing gas with a catalyst containing a catalytically active component element from group VIII of the Periodic table, characterized in that the catalyst is in the form of a ceramic foam obtained by the method according to any of paragraphs.1-8.

 

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