EP2459312A2

EP2459312A2 - Method for production of chlorine by gas phase oxidation on nano-structured ruthenium carrier catalysts

Info

Publication number: EP2459312A2
Application number: EP10732315A
Authority: EP
Inventors: Timm Schmidt; Christoph Gürtler; Jürgen KINTRUP; Thomas Ernst MÜLLER; Tim Loddenkemper; Frank Gerhartz; Walther Müller
Original assignee: Bayer MaterialScience AG
Current assignee: Covestro Deutschland AG
Priority date: 2009-07-25
Filing date: 2010-07-14
Publication date: 2012-06-06
Also published as: TW201117880A; WO2011012226A2; JP2013500145A; KR20120040701A; DE102009034773A1; WO2011012226A3; IN2012DN00739A; US20120148478A1; CN102711986A

Abstract

The present invention relates to a method for producing chlorine by gas phase oxidation having a carried catalyst on the basis of ruthenium, characterized in that the catalyst carrier has a plurality of pores having a pore diameter of >50 nm and carries nanoparticles comprising ruthenium and/or ruthenium compounds as catalytically active components.

Description

Process for the production of chlorine by gas-phase oxidation on nanostructured ruthenium. to support catalysts

The present invention relates to a process for the preparation of chlorine by gas phase oxidation with a supported catalyst based on ruthenium, characterized in that the catalyst support has a plurality of pores, with a pore diameter> 50 nm and ruthenium and / or ruthenium compounds containing nanoparticles as catalytically active Components carries.

The process of catalytic hydrogen chloride oxidation with oxygen in an exothermic equilibrium reaction, developed by Deacon in 1868, was at the beginning of technical chlorine chemistry:

4 HCl + O ₂ -> 2 Cl ₂ + 2 H ₂ O.

However, the chloroalkali electrolysis strongly pushed the Deacon process into the background. Almost all of the chlorine was produced by the electrolysis of aqueous saline [Ulimann Encyclopedia of Industrial Chemistry, 7th Edition, 2006]. However, the attractiveness of the Deacon process has increased again recently, as the global demand for chlorine is growing faster than the demand for caustic soda. This development is countered by the process for the production of chlorine by oxidation of hydrogen chloride, which is decoupled from the sodium hydroxide production. In addition, hydrogen chloride precipitates in large quantities, for example in phosgenation reactions, such as in isocyanate production, as by-product.

The oxidation of hydrogen chloride to chlorine is an equilibrium reaction. The position of the equilibrium shifts with increasing temperature to the detriment of the desired end product. It is therefore advantageous to use catalysts with the highest possible activity, which allow the reaction to proceed at low temperature.

The first catalysts for the hydrogen chloride oxidation contained as active component copper chloride or oxide and were already described in 1868 by Deacon. However, these showed low activity at low temperature (<400 ⁰ C). Although the activity could be increased by increasing the reaction temperature, it was disadvantageous that the volatility of the active components at high temperatures led to a rapid decrease in the catalyst activity and to the discharge of the active component from the reactor.

EP 0184413 describes the oxidation of hydrogen chloride with catalysts based on chromium oxides. However, the process realized thereby requires high catalyst loadings due to insufficient catalyst activity and high reaction temperatures. The first catalysts for the hydrogen chloride oxidation with the catalytically active component ruthenium were already described in 1965 in DE 1567788; in this case starting from RuCb, for example supported on silica or alumina. However, the activity of these RuCb / SiOa catalysts was very low. Further Ru-based catalysts with the active component ruthenium oxide or ruthenium mixed oxide and as carrier material various oxides, such as, for example, titanium dioxide, zirconium oxide, etc., have been claimed in DE-A 19748299. The content of ruthenium oxide is 0.1% by mass to 20% by mass and the average particle diameter of ruthenium oxide is 1.0 nm to 10.0 nm. Further Ru catalysts supported on titanium dioxide or zirconium dioxide are known from DE-A 19734412. For the preparation of the ruthenium chloride and ruthenium oxide catalysts described therein, which contain at least one compound titanium dioxide and zirconium dioxide, a number of Ru starting compounds have been indicated, such as ruthenium-carbonyl complexes, ruthenium salts of inorganic acids, ruthenium-nitrosyl complexes, ruthenium Amine complexes, ruthenium complexes of organic amines or ruthenium-acetylacetonate complexes. In a preferred embodiment, TiC> _{2 was} used as a carrier in the form of rutile.

DE 102007020154Al and DE 102006024543 A1 describe a process for catalytic hydrogen chloride oxidation, in which the catalyst is tin dioxide (as carrier), preferably tin dioxide in the cassiterite structure and at least one halogen-containing ruthenium compound (DE 102007020154Al) or at least one oxygen-containing ruthenium compound (DE102006024543A1). contains.

The ruthenium-free catalysts previously developed for the Deacon process are either too inactive or too unstable. Although the ruthenium-supported catalysts described hitherto are suitable in principle for use in the Deacon process, the preferred supports rutile titanium dioxide and cassiterite tin dioxide have only small surfaces due to their crystalline structure, which is disadvantageous for their use as carriers in the HCl oxidation ,

The object of the present invention was therefore to provide a catalytic system for the oxidation of hydrogen chloride, which offers a higher specific (on the ruthenium content) related activity than the catalysts known from the prior art.

Surprisingly, it has been found that by specific preparation of nano-structured catalysts, the specific (i.e., ruthenium-related) activity and (high-temperature) stability can be significantly increased.

The present invention relates to a catalyst material for the thermocatalytic production of chlorine from hydrogen chloride and oxygen-containing gas, based on a ruthenium-based carrying supported catalyst, characterized in that the catalyst support has a plurality of pores, with a pore diameter> 50 nm and ruthenium and / or ruthenium compounds containing nanoparticles as catalytically active components. The thermocatalytic production of chlorine from hydrogen chloride and oxygen-containing gas is also generally referred to hereinafter as the Deacon process.

Preferably, at least 50%, more preferably at least 80%, of the pore volume of the catalyst material of the present invention is present in pores whose diameter is within the macroporous range, i. > 50 nm. This macroporosity allows a uniform loading of the catalyst support with nanoparticles, prevents the blocking of pores by agglomeration of nanoparticles and leads to reduced pore diffusion limitation during the Deacon reaction.

For the purposes of the invention, mercury porosimetry is used to determine the pore volume and the pore diameter. Here, the measurement is based on a mercury contact angle of 130 ° and a surface tension of 480 dyn / cm ² .

The catalyst material preferably comprises one or more compounds of the series: aluminum compounds, silicon compounds, titanium compounds, zirconium compounds or tin compounds as support material, particularly preferably aluminum compounds and / or silicon compounds and very particularly preferably oxides, mixed oxides or mixed oxides of one or more of the metals of the series: aluminum, Silicon, titanium, zirconium or tin. Particularly preferred are mixed oxides of aluminum and silicon. In one possible embodiment, binders are added, such as. B. μ-Al ₂ θ ₃ , whose primary function is not that of a carrier of the active component.

The ruthenium-containing nanoparticles present on the catalyst material as catalytically active component preferably comprise one or more compounds from the series: ruthenium oxides, ruthenium mixed oxides, mixed ruthenium oxides, ruthenium oxyhalides, ruthenium halides or metallic ruthenium. Particular preference is given to ruthenium chloride, ruthenium oxychloride or mixtures of ruthenium oxide and ruthenium chloride.

The ruthenium-containing nanoparticles present on the catalyst preferably have at least 50% of a maximum diameter of 50 nm, more preferably at least 50% have a diameter of 5 nm to 50 nm, very preferably at least 80% have a diameter of 5 nm 50 nm. Most preferably, the average diameter of the present on the catalyst, ruthenium-containing nanoparticles, 10 to 30 nm. It is surprisingly not desirable to seek a maximum dispersion of ruthenium (ie, as small as possible Rutheniumprimärpartikel, eg below 5 nm) , The ruthenium content of the catalysts is preferably set at up to 20% by weight, preferably 0.1 to 20% by weight, more preferably 0.5 to 5% by weight, based on the total mass of the catalyst. Excessive loading may result in adverse agglomeration of nanoparticles.

Additional nanoparticles with the function of a further active component or as promoters are preferably present on the catalyst material, particularly preferably one or more further metals, metal compounds and mixed compounds of the elements Ag, Au, Bi, Ce, Co, Cr, Cu, Ni, Sb, Sn , Ti, W, Y, Zn, Zr and the platinum metals, most preferably the elements Bi, Sb, Sn and Ti. Preferably, these additionally present on the catalyst nanoparticles oxides, mixed oxides, mixed oxides, oxyhalides, halides, the reduced metals or their alloys.

Preferably, a mass fraction of the present on the catalyst material additional nanoparticles of up to 20% by mass, more preferably up to 10% by mass, based on the total mass of the catalyst. Excessive loading may result in adverse agglomeration of nanoparticles.

Preferably, the additional nanoparticles present on the catalyst have at least 50% of a maximum diameter of 50 nm, more preferably at least 50% have a diameter of 3 nm to 50 nm, most preferably at least 80% have a diameter of 3 nm to 50 nm. Most preferably, the average diameter, the existing on the catalyst, additional nanoparticles, between 5 and 30 nm.

In a possible preferred embodiment, nanoparticles which contain at least ruthenium and at least one further metal, preferably Ag, Au, Bi, Ce, Co, Cr, Cu, Ni, Sb, Sn, Ti, W, Y, Zn, are present on the catalyst. Zr and platinum metals as a promoter, most preferably Bi, Sb, Sn and Ti, ie can be referred to as bimetallic or multimetallic. The nanoparticles characterized in this way contain oxides, mixed oxides, mixed oxides, oxyhalides, halides, metals and alloys.

Preferably, the bimetallic or multimetal nanoparticles present on the catalyst have at least 50% of a maximum diameter of 50 nm, more preferably at least 50% have a diameter of 5 nm to 50 nm, most preferably at least 80% have a diameter of 5 nm up to 50 nm. Most preferably, the average diameter of the present on the catalyst, bimetallic or multimetal nanoparticles 10 to 30 nm.

Preferably, a mass fraction of the bimetallic or multimetal nanoparticles present on the catalyst of up to 30 wt .-% is set, particularly preferably up to 20 wt .-%, based on the total mass of the catalyst. Excessive loading leads to disadvantageous agglomerations of nanoparticles.

The nanoparticles are preferably prepared by flame pyrolysis. A preferred method of preparation is as follows:

At least one precursor is presented in powder form. If bimetallic or multimetal nanoparticles are to be prepared, various pulverulent precursors are preferably poured together and mixed. These powders are fed to a plasma chamber or free flame and vaporized abruptly therein. The generated gaseous metal compounds are discharged from the plasma and condense in a cooler area, whereby nanoparticles are formed with a defined size distribution. These nanoparticles are stabilized in an emulsion by the addition of surfactants and detergents. Preferably, water or an organic solvent is used for the preparation of the emulsion. This emulsion, or a mixture of two or more emulsions containing the active component, further active components and / or promoters, is then used to impregnate a catalyst support, preferably by a method commonly referred to in the specialist literature as "incipient wetness". In this method, as many of the active components containing impregnation solution is presented as the carrier to be impregnated can just record and thus ensures that the active components are completely absorbed by the carrier.Possible further embodiments can be found, for example, the patent application US20080277270-A1.

In order to remove potentially interfering organic compounds from the catalyst surface and to bind and stabilize the nanoparticles on the catalyst, the catalyst is then calcined at elevated temperatures. Preferably, this calcination is carried out in an atmosphere containing oxygen, more preferably in air or an inert gas-oxygen mixture. The temperature is up to 800 ⁰ C, preferably between 250 ⁰ C and 600 ⁰ C. The calcination time is appropriately selected preferably between Ih and 50h. The catalyst impregnated with the emulsion is preferably dried before calcination, preferably at reduced pressure and expediently between 1 h and 50 h.

As further promoters are compounds of basic metals in question (eg, alkali, alkaline earth and rare earth metal salts), preferred are compounds of alkali metals, especially Na and Cs and alkaline earth metals, particularly preferred are compounds of alkaline earth metals, in particular Sr and Ba. In a preferred embodiment, the basic metals are used as oxides, hydroxides, chlorides, oxychlorides or nitrates. In a preferred embodiment, these types of promoters are applied to the catalyst by impregnation or CVD methods. The carrier used according to the invention is preferably commercially available (for example from Saint Gobain Norpro).

The catalysts according to the invention for the hydrogen chloride oxidation are characterized by high activity coupled with high stability at high temperatures.

The catalytic hydrogen chloride oxidation may preferably be adiabatic or isothermal or approximately isothermal, batchwise, but preferably continuously or as a fixed bed process, preferably as a fixed bed process, more preferably in tube bundle reactors to heterogeneous catalysts at a reactor temperature of 180 to 500 ⁰ C, preferably 200 to 400 ^0th C, more preferably 250 to 380 ⁰ C and a pressure of 1 to 25 bar (1000 to 25000 hPa), preferably 1.2 to 20 bar, more preferably 1.5 to 17 bar and in particular 2.0 to 15 bar are performed ,

Typical reactors in which the catalytic hydrogen chloride oxidation is carried out are fixed bed or fluidized bed reactors. The catalytic hydrogen chloride oxidation can preferably also be carried out in several stages.

In the case of the adiabatic, isothermal or approximately isothermal mode of operation, it is also possible to use a plurality of reactors with intermediate cooling, that is to say 2 to 10, preferably 2 to 6, particularly preferably 2 to 5, in particular 2 to 3, connected in series. The hydrogen chloride can be added either completely together with the oxygen before the first reactor or distributed over the various reactors. This series connection of individual reactors can also be realized in one apparatus.

A further preferred embodiment of a device suitable for the method consists in using a structured catalyst bed in which the catalyst activity increases in the flow direction. Such structuring of the catalyst bed can be done by different impregnation of the catalyst support with active material or by different dilution of the catalyst with an inert material. As an inert material, for example, rings, cylinders or balls of titanium dioxide, zirconium dioxide or mixtures thereof, alumina, steatite, ceramic, glass, graphite or stainless steel can be used. In the preferred use of shaped catalyst bodies, the inert material should preferably have similar external dimensions.

Suitable shaped catalyst bodies are shaped bodies of any shape, with preference being given to tablets, extrudates, rings, cylinders, stars, wagon wheels or spheres, particular preference being given to rings, cylinders or star strands as a mold. The dimensions (diameter in the case of spheres) of the shaped bodies are preferably in the range from 0.2 to 10 mm, particularly preferably 0.5 to 7 mm. As an alternative to the previously described finely divided catalyst (mold) bodies, the support may also be a monolith of support material. An alternative preferred embodiment is foams, sponges or the like with three-dimensional connections within the carrier body, as well as monoliths and carrier bodies with cross-flow channels.

The monolithic carrier may have a honeycomb structure, but also an open or closed cross-channel structure. The monolithic carrier has a preferred cell density of 100 to 900 cpsi (cells per square inch), more preferably 200 to 600 cpsi.

A monolith according to the present invention is e.g. in "Monoliths in multiphase catalytic processes - aspects and prospects" by F. Kapteijn, J.J. Heiszwolf, T.A. Nijhuis and J.A. Moulijn, Cattech 3, 1999, p24.

The conversion of hydrogen chloride in a single pass is in the range of 15 to 100% and may preferably be limited to 15 to 90%, preferably 40 to 90%, particularly preferably 60 to 90%. After separation, unreacted hydrogen chloride can be partially or completely recycled to the catalytic hydrogen chloride oxidation. The volume ratio of hydrogen chloride to oxygen at the reactor inlet is preferably 1: 1 to 20: 1, particularly preferably 2: 1 to 8: 1, very particularly preferably 2: 1 to 6: 1.

The heat of reaction of the catalytic hydrogen chloride oxidation can be used advantageously for the production of high-pressure steam. This can be used to operate a phosgenation reactor and / or distillation columns, in particular isocyanate distillation columns.

In a final step of the deacon process, the chlorine formed is separated off. The separation step usually comprises several stages, namely the separation and optionally recycling of unreacted hydrogen chloride from the product gas stream of the catalytic hydrogen chloride oxidation, the drying of the obtained, substantially chlorine and oxygen-containing stream and the separation of chlorine from the dried stream.

The separation of unreacted hydrogen chloride and water vapor formed can be carried out by condensation of aqueous hydrochloric acid from the product gas stream of hydrogen chloride oxidation by cooling. Hydrogen chloride can also be absorbed in dilute hydrochloric acid or water.

The following examples illustrate the present invention: Examples

Example 1 (comparative example: Preparation of a catalyst not according to the invention)

100 g of TiO ₂ pellets (cylindrical, diameter about 2 mm, length 2 to 10 mm, Saint-Gobain) were impregnated with a solution of ruthenium chloride n-hydrate in H ₂ O, so that the Ru content was 3 masses. % amounted to. The wet pellets thus obtained were dried overnight at 60 ⁰ C and introduced in the dry state under a nitrogen purge in a solution of NaOH and 25% hydrazine hydrate in water and Ih allowed to stand. Excess water was then evaporated. The moist pellets were dried for 2 h at 60 ⁰ C and then washed 4x with 300g of water. The moist pellets thus obtained were in the muffle furnace (air) for 20 min. dried at 120 ⁰ C and then calcined for 3h at 350 ⁰ C.

Example 2: Preparation of exemplified, inventive catalysts

Stable oxides of Ru (RuO ₂ ), Sn (SnO ₂ ), Ni (NiO), Sb (Sb ₂ O ₅ ), Zr-Y (90 mass% ZrO ₂ , 10 mass% Y ₂ Os), Ti (TiO ₂ ), Bi (Bi ₂ O ₅ ) were presented as μm-scale powder. These powders were individually (samples with the names 2a-b, 2e-i -> monometallic nanoparticles) or premixed (samples with the names 2c-d - ^ bimetallic nanoparticles) supplied to a plasma chamber and therein (at a temperature above 20,000 K) evaporates abruptly. The resulting gaseous metal compounds were discharged from the plasma and condensed in a cooler range (temperature less than 500 ⁰ C), whereby nanoparticles were formed with a defined size distribution. These nanoparticles were stabilized in an aqueous emulsion by adding an amine-based non-ionic comb polymer (manufacturer: SDC material) with the content of nanoparticles adjusted to 7.5% by weight. In the emulsion, the desired ratio between ruthenium nanoparticles and additional nanoparticles on the catalyst was adjusted and thus the catalyst support by means of a method which is commonly referred to in the literature as "incipient wetness" repeatedly impregnated until the desired total charge on the catalyst support In this method, as much of the impregnation solution containing the active components is presented as the support to be impregnated can just take up, thereby ensuring that the active components are completely absorbed by the support The properties of the support specified by Saint-Gobain are as follows:

> average pore diameter: 1.2 μm, BET surface area: 30 m ² / g > Pore volume: 0.55 cnVg, water absorption capacity: 60% by weight

> ^■ Composition: 82 wt .-% alpha / transition Al ₂ O _3, 18 wt .-% SiO ₂

> ^• Dimensions: d = 3-4 mm, 1 = 6-8 mm (2a-d, 2h-i); d = 3-4 mm, 1 = 3-4 mm (2e-g)

The wet catalyst samples were dried between the impregnation steps and finally at 110 ⁰ C for 2-5 h and calcined at 550 ⁰ C for 2 h in air. The mass fraction of the metallic content of the nanoparticles in the total mass of the catalysts can be taken from Table 1 (determined by means of XRF).

Tab. 1: Mass fraction of the metallic content of the nanoparticles on the total mass of the catalysts (determined by means of XRF)

Ru Sn Ni Sb Zr / Y Ti Bi

^Kat ro _/ . _{Λ (} o _{/ o) (} o _{/ o) (} o _{/ o) (} o _{/ o) (} o _{/ o) (} o _{/ o)}

2a 1.9

2b 1.6 4.5

2c 1.5 29

2d 2,1 11

2e 1.7 5.0

2f 1.9 5.1

2g 1.6 5.2

2h 2.2 5.9

2i 2.4 8.9

Example 3 (Comparative Example): Test of a catalyst not according to the invention (from Example 1)

Ig of the catalyst moldings designated 1 were diluted with inert Spheriglaskugeln in a quartz reaction tube (inner diameter 10 mm) presented. This approach was subjected to the same measurement program as in Example 4. The RZA _Ru development and the developed key figures can be found in Tab Tab. 2: RZA _Ru development of a catalyst not according to the invention.

"Start RZA _Ru after 19h after 37h after 103h after 121h

[g / gh] [g / gh] [g / gh] [g / gh] [g / gh] ^a

1 27.0 23.0 21.7 20.3 n.b. 26.9 0.061

Definition of parameters a and b see example 4; n.d. : not determined.

Example 4 Test of Inventive Catalysts (from Example 2)

Each Ig of the shaped catalyst body with the name 2a-i were diluted with inert Spheriglaskugeln in a quartz reaction tube (inner diameter 10 mm) presented. After heating under a constant stream of nitrogen, the mixtures each with a gas mixture (10 L / h), composed of 1 L / h of hydrogen chloride, 4 L / h of oxygen, 5 L / h of nitrogen at 380 ⁰ C for about 16h. Subsequently, the temperature was lowered to 330 ⁰ C and determines the space-time yield (starting-RZA). Thereafter, the temperature was raised to 430 ⁰ C. To measure the deactivation, the temperature was lowered in intervals to 330 ⁰ C (RZA after xh). The space-time yield was determined in which the product gas stream of the respective reactors for about 15 min. was passed through a 20% potassium iodide solution and the resulting iodine was then titrated with 0.1 N thiosulfate standard solution (duplicate determination). From the so determined amount of chlorine specific (on the ruthenium content) space-time yield (RZA) was determined according to the following formula (Tab. 3a / b):

RZA _Ru = g (Chloro) * g ^"1 (ruthenium mass on the catalyst used) * h ^{" 1} (time) The RZA _Ru evolution was modeled with a power approach:

RZA _Ru = at ^b (t in h TOS at 430 ^° C), where a is indicative of the initial activity and b is indicative of the deactivation rate. These two parameters were also included in Tab. 3a / b. Tab. 3a: RZA _Ru development of catalysts according to the invention. κ start RZA _Ru after 109h after 123h after 198h

[g / gh] [g / gh] [g / gh] [g / gh]

2a 18.4 17.9 17.4 16.3 18.5 0.016

2b 33.8 30.0 29.4 28.8 33.8 0.029

2c 27.3 20.7 19.3 18.0 27.5 0.072

2d 25.2 17.6 17.1 16.7 25.2 0.079

Tab. 3b: RZA _Ru - development of catalysts according to the invention. κ start RZA _Ru after 19h after 37h after 103h after 121h

[g / gh] [g / gh] [g / gh] [g / gh] [g / gh]

2e 19.4 21.2 22.4 21.8 21.2 nb ¹ nb ¹

2f 33.7 26.3 25.3 22.1 22.6 33.8 0.086

2g 20.0 18.8 18.8 17.5 18.1 20.1 0.024

2h 23.6 22.3 21.4 20.9 20.5 23.8 0.029

2i 30.7 29.0 28.5 26.9 nb ¹ 30.9 0.026

¹ nb: not determined.

The stability (modeled deactivation parameter -b) of some exemplified, inventive catalysts (2a, 2b, 2g, 2h, 2i) is obviously in some cases significantly higher than that of the prior art catalyst not according to the invention. The specific initial activity of some exemplified, erfϊndungsgemäßer catalysts (2b, 2f, 2i) is obviously partially significantly higher than that of the non-inventive catalyst according to the prior art. The catalyst samples 2a and 2c even have significantly higher (high temperature) stability and significantly higher initial activity than the prior art catalyst.

Example 5: Size distribution of the nanoparticles on the catalyst

A few 10 mg of the inventive catalysts cited by way of example with the names 2a, 2b, 2c and 2b were finely ground, slurried in ethanol and the resulting suspension was dropped onto a sample carrier for TEM measurements (Tecnai20, Megaview III). In TEM, different areas of the two samples were examined. In Fig. 1 (cat. 2a), Fig. 2 (Cat. 2b), Fig. 3 (Cat. 2c) and Fig. 4 (Cat. 2d), exemplary characteristic regions of the catalyst samples are shown by way of illustration.

Fig. 1 (Cat. 2a): 34 primary particles with a diameter between 5 and 34 nm (mean value of 16 nm) were counted.

Fig. 2 (Cat 2b): The primary particle distribution (ruthenium dioxide and tin dioxide) is similar to that of 2a.

Fig. 3 (Cat. 2c): The primary particle distribution (ruthenium dioxide and tin dioxide) is similar to that of

2a.

Fig. 4 (Cat. 2d): The primary particle distribution (ruthenium dioxide and tin dioxide) is similar to that of 2a.

In contrast to the catalysts according to the invention, ruthenium dioxide on rutile TiC> ₂ (see Example 1) evidently exists as a carrier-coating layer owing to the comparable lattice spacing of the two rutile structures ("Development of an improved HCl oxidation process: structure of the RuCVrutile Tiθ ₂ catalyst "by Seki, Kohei, Iwanaga, Kiyoshi, Hibi, Takuo, Issoh, Koharto, Mori, Yasuhiko, Abe, Tadashi in Studies in Surface Science and Catalysis (2007), 172 (Science and Technology in Catalysis 2006), 55-60). in the same publication this catalyst are compared with ruthenium catalysts on the basis of Al ₂ O ₃ or SiO _2, which have a significantly lower activity despite assumable high dispersion. Obviously, the high dispersion is on these carriers in comparison with the planar Application to rutile TiO ₂ detrimental to the catalytic properties.

However, the nano-structured supported ruthenium catalysts according to the invention with defined ruthenium primary particle sizes are obviously even superior to ruthenium-supported catalysts based on RuUl-TiO ₂ .

Claims

claims

1. Catalyst material for the thermo-catalytic production of chlorine from hydrogen chloride and oxygen-containing gas, based on a ruthenium-based supported catalyst, characterized in that the catalyst support has a plurality of pores, with a pore diameter> 50 nm and ruthenium and / or ruthenium compounds containing nano - Particles carries as catalytically active components.

2. Catalyst material according to claim 1, characterized in that at least 50%, preferably at least 80% of the pore volume of the catalyst material is present in pores whose diameter is greater than 50 nm.

3. Catalyst material according to one of claims 1 to 2, characterized in that the catalyst support comprises one or more compounds of the series: aluminum compounds, silicon compounds, titanium compounds, zirconium compounds or tin compounds as support material, preferably aluminum compounds and / or silicon compounds.

4. Catalyst material according to claim 3, characterized in that the catalyst support comprises oxides, mixed oxides or mixed oxides of one or more of the metals of the series: aluminum, silicon, titanium, zirconium or tin as support material, preferably mixed oxides of aluminum and silicon.

5. Catalyst material according to claim 1, characterized in that the ruthenium-containing nanoparticles present on the catalyst comprise one or more compounds from the series: ruthenium oxides, ruthenium mixed oxides, mixed ruthenium oxides, ruthenium oxyhalides, ruthenium halides, metallic ruthenium as the catalytically active component , preferably ruthenium chloride, ruthenium oxychloride or mixtures of ruthenium oxide and ruthenium chloride.

6. Catalyst material according to one of claims 1 to 5, characterized in that the ruthenium-containing nanoparticles have at least 50% a diameter of at most 50 nm, preferably at least 50% have a diameter of 5 nm to 50 nm, particularly preferably at least 80% have a diameter of 5 nm to 50 nm.

7. Catalyst material according to one of claims 1 to 6, characterized in that the ruthenium-containing nanoparticles have an average diameter of 10 to 30 nm.

8. Catalyst material according to one of claims 1 to 7, characterized in that the catalyst has a ruthenium content of up to 20 wt .-%, preferably from 0.5 to 5 wt .-%, based on the total mass of the catalyst material.

9. Catalyst material according to one of claims 1 to 8, characterized in that the catalyst material additionally comprises nanoparticles based on one or more further metals or metal compounds as further active component or as promoter, preferably one or more further metals or metal compounds and mixed compounds of the elements Ag, Au, Bi, Ce, Co, Cr, Cu, Ni, Sb, Sn, Ti, W, Y, Zn, Zr and the platinum metals, particularly preferably the elements Bi, Sb, Sn and Ti.

10. Catalyst material according to claim 9, characterized in that the additional nanoparticles comprise as metal compounds oxides, mixed oxides, mixed oxides, oxyhalides, in particular oxychlorides, halides, in particular chlorides or metals, or metal alloys of the metals mentioned in claim 9.

11. Catalyst material according to one of claims 1 to 10, characterized in that the proportion of additionally present on the catalyst nanoparticles up to 20 wt .-%, preferably up to 10 wt .-%, based on the total mass of the catalyst material.

12. Catalyst material according to one of claims 1 to 11, characterized in that the additionally present on the catalyst nanoparticles to at least 50% have a maximum diameter of 50 nm, preferably at least 50% have a diameter of 3 nm to 50 nm, especially preferably at least 80% have a diameter of 3 nm to 50 nm.

13. Catalyst material according to one of claims 1 to 12, characterized in that the additional nanoparticles have an average diameter of 5 to 30 nm.

14. A process for the preparation of a catalyst material according to any one of claims 1 to 13, characterized in that the catalyst is prepared by at least the following process steps: a) synthesis of ruthenium and / or ruthenium compounds containing nanoparticles via flame pyrolysis, b) stabilization of ruthenium and / or Nano particles containing ruthenium compounds in an emulsion, c) (multiple) impregnation of the support with the emulsion from step b), d) calcination of the impregnated catalyst at elevated temperature.

15. A process for the thermocatalytic production of chlorine from hydrogen chloride and oxygen-containing gas, characterized in that a catalyst material according to any one of claims 1 to 13 is used as a catalyst.

16. The method according to claim 15, characterized in that the hydrogen chloride oxidation is adiabatic or isothermal or approximately isothermal, preferably adiabatic, in particular continuously as flow or fixed bed process, preferably as a fixed bed process at a reactor temperature of 180 to 500 ⁰ C, preferably 200 to 400 ⁰ C, more preferably 250 to 380 ⁰ C and a pressure of 1 to 25 bar (1000 to 25000 hPa), preferably 1.2 to 20 bar (1200 to 20,000 hPa), more preferably 1.5 to 17 bar (1500 to 17000 hPa) and in particular 2.0 to 15 bar (2000 to 15000 hPa) is performed.