EP2771108A1

EP2771108A1 - Catalyst and method for producing chlorine by means of a gas-phase oxidation

Info

Publication number: EP2771108A1
Application number: EP12775024.8A
Authority: EP
Inventors: Timm Schmidt; Maximilian Moser; Walther Müller
Original assignee: Bayer Intellectual Property GmbH
Current assignee: Covestro Intellectual Property GmbH and Co KG
Priority date: 2011-10-24
Filing date: 2012-10-19
Publication date: 2014-09-03
Also published as: JP2014534062A; JP6316194B2; WO2013060628A1; CN103889568A; JP6595022B2; JP2018089625A; KR20140086977A; IN2014CN02995A; US20140248208A1; CN103889568B

Abstract

The invention relates to known catalysts containing cerium or other catalytically active components for producing chlorine by means of a catalytic gas-phase oxidation of hydrogen chloride with oxygen. A catalyst material for producing chlorine by means of a catalytic gas-phase oxidation of hydrogen chloride with oxygen is described, wherein the catalyst comprises at least oxide compounds of the cerium as active components and zirconium dioxide as supporting components, and the catalyst is characterized by a particularly high space-time yield measured in kgC12/LREAKTOR·h with respect to the reactor volume.

Description

Catalyst and process for producing chlorine by gas phase oxidation

The invention is based on known cerium or other catalytically active components containing catalysts for the production of chlorine by catalytic gas phase oxidation of hydrogen chloride with oxygen. The invention relates to a supported catalyst for the production of chlorine by catalytic gas phase oxidation of hydrogen chloride with oxygen, wherein the catalyst comprises at least oxide compounds of cerium as active component and zirconium dioxide as the carrier component and wherein the catalyst by a particularly high on the reactor volume related space-time yield measured in kgci2 / LREAKTOR-h. 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:

4HCl + 0 ₂ = ^ 2Ch + 2H ₂ 0.

However, the chloroalkali electrolysis strongly pushed the Deacon process into the background. Nearly all chlorine production was achieved by electrolysis of aqueous saline solutions [Ullmann Encyclopedia of industrial chemistry, seventh release, 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 first catalysts for HCl gas phase oxidation contained copper in the oxidic form as the active component and had already been described by Deacon in 1868. These catalysts deactivated rapidly because the active component volatilized under the high process temperatures.

Also, the HCl gas phase oxidation by means of chromium oxide-based catalysts is known. However, chromium-based catalysts tend to form under oxidizing conditions chromium (VI) oxides, which are very toxic and must be kept technically complex from the environment. In addition, a short duration is assumed in other publications (WO 2009/035234 A, page 4, line 10).

Ruthenium-based catalysts for HCl gas-phase oxidation were first described in 1965, but the activity of these RuCl3 / SiO2 catalysts was rather low (see: DE 1567788 AI). Other catalysts with the active components ruthenium dioxide, mixed oxides of ruthenium or ruthenium chloride in combination with various carrier oxides, such as titanium dioxide or tin dioxide have also been described (see, for example: EP 743277A1, US-A-5908607, EP 2026905 AI and EP 2027062 A2). with ruthenium-based catalysts, therefore, the optimization of the carrier is already well advanced.

Ruthenium-based catalysts have quite high activity and stability at a temperature in the range of 350-400 ° C. But the stability of ruthenium-based catalysts above 400 ° C is still not clearly demonstrated (WO 2009/035234 A2, page 5, line 17). In addition, the platinum group metal ruthenium is very rare, very expensive, and the world market price for ruthenium is highly volatile. There is therefore a need for alternative catalysts with higher availability and comparable effectiveness.

WO 2009/035234 A2 describes ceria catalysts for HCl gas phase oxidation (see claims 1 and 2), although at least one support is contemplated herein. However, possible suitable carriers are not disclosed in detail. The disclosure of DE 10 2009 021 675 A1 is considered as the closest prior art to the invention and describes a process for the preparation of chlorine by catalytic oxidation of hydrogen chloride in the presence of a catalyst comprising an active component and optionally a support material and wherein the active component comprises at least one cerium oxide compound. Example 5 of DE '675 describes a catalyst material with ceria on lanthanum-zirconium oxide as catalyst support and describes the effectiveness of this catalyst material in application example 11 of D E' 675 in more detail. From DE '675 shows that the activity of this catalyst material is the lowest compared to all other catalysts tested there. Examples of suitable carrier materials for the cerium oxide catalyst are the following: silicon dioxide, aluminum oxide (for example in a or γ modifications), titanium dioxide (as rutile, anatase, etc.), tin dioxide, zirconium dioxide, uranium oxide, carbon nanotubes Tubes (carbon nanotubes) or mixtures thereof, without further examples to this or advantages and disadvantages of the listed supports are weighed against each other (see paragraph [0017] of DE '675) The above list is an arbitrary list of known support materials for Ruthenium catalysts in the HCl gas phase oxidation, which is extended by a known active component (uranium). The person skilled in the catalyst development takes the disclosure of DE 10 2009 021 675 AI, that the application of cerium oxide in supported catalysts provides no useful catalyst material.

The object of the present invention is, starting from the aforementioned prior art, to find an improved catalyst material which, instead of the rare ruthenium, is based on cerium as catalytically active component and in supported form a significantly higher Has effectiveness. In particular, it is an object to identify for the Aktivkom onente ceria an optimal catalyst support for use in the HCl gas phase oxidation.

The object is achieved by a support of oxide compounds of cerium on zirconium dioxide.

Surprisingly, it was found in particular that · at a comparable loading of 7% by weight, the best new CeCh / ZrC catalyst (1.28 kg.sup.2 / kgKAT-h, Ex. 5) was 2.6 times higher based on the catalyst mass Space-time yield has as the best non-inventive alternative catalyst (CeCh / AkOs: 0.49 kgci2 / kgKA h, Ex. 7), the active component cerium is therefore significantly better used in these novel CeCVZrC catalysts than other common carriers, and

• that the best new CeC / ZrC catalyst (1.98 kgci2 / kgKArh, Ex. 6) has a 4.3 time higher space-time yield relative to the reactor volume than the best non-inventive alternative catalyst (CeCk / AhOs: 0) , 46 kgci2 / kgKArh, Ex. 24). The reactor volume is therefore significantly better used in these novel CeCk / ZrCk catalysts than other common carriers, which of course also has a positive effect on the

Pressure loss across the filled reactor and thus the power consumption during operation of the HC1 oxidation effect.

The invention relates to a catalyst material of porous catalyst support and catalytic coating for a process for the thermocatalytic production of chlorine from hydrogen chloride and oxygen-containing gas, wherein the catalyst material comprises at least: at least one oxide compound of cerium as a catalytic active component and at least zirconium dioxide as a carrier component, characterized in that the content of lanthanum in the form of La 2 O 3 based on the calcined catalyst is less than 5% by weight, in particular measured by the method of X-ray fluorescence analysis for the metal content and X-ray diffraction to detect the oxide structure.

In a preferred embodiment, the new catalyst material is characterized in that the calcined catalyst has a bulk density of at least 1000 kg / m ³ , preferably of at least 1200 kg / m ³ , more preferably of at least 1300 kg / m ³ , in particular measured in a stand cylinder with DN 1 00 and 350 mm filling height, and wherein the mean extent of the particles of the catalyst material is on average at least 0.5 mm, preferably at least 1 mm. With the same volume-time yield based on the catalyst mass, catalysts with a high bulk density are to be preferred, since the at least required reactor volume is reciprocal to the bulk density. Since, for reasons of corrosion, technically more complex and expensive Ni-containing construction materials are generally used for the reactors, increasing the catalyst bulk density can be a significant advantage. in particular when used in tube bundle reactors in which the reactor structure can be reduced. A reduced reactor volume also has a positive effect on the pressure drop over the filled reactor and thus the power consumption, as stated above.

In a preferred embodiment, the catalyst support comprises at least 50% by weight, preferably at least 90% by weight, particularly preferably at least 99% by weight, of zirconium dioxide, in particular measured by the method of X-ray fluorescence analysis for the metal content and X-ray diffraction (X. Ray Diffraction) for the detection of the oxide structure.

In a preferred embodiment, the new catalyst material is characterized in that the content of lanthanum in the form of La2Ü3 based on the calcined catalyst less than 3 wt .-%, preferably less than 2 wt .-%, more preferably less than 1 wt. %, most preferably substantially free of lanthanum constituents, in particular measured by the method of X-ray fluorescence analysis for the metal content and X-ray diffraction (X-ray diffraction) for the detection of the oxide structure. In a particularly preferred embodiment, the new catalyst material is characterized in that the content of Y ₂ O ₃ based on the calcined catalyst is less than 5 wt .-%, in particular measured by the method of X-ray fluorescence analysis for the metal content and X-ray diffraction (X-ray diffraction ) for the detection of the oxide structure. The La203 and Y2O3, which are often used as structural stabilizers, appear to affect the particular interaction between CeO 2 and ZrO 2 (see examples). In a particularly preferred embodiment, the new catalyst material is characterized in that the content of SO3 based on the calcined catalyst is less than 3 wt .-%, in particular measured by the method of X-ray fluorescence analysis for the metal content and X-ray diffraction (X-ray diffraction) Evidence of the oxide structure, [additional alternative claim] Superacid centers in SO3-doped ZrO2 appear to be rather detrimental to the space-time yield (see examples).

In a preferred embodiment, the novel catalyst material is characterized in that the porous catalyst support in the uncoated state (ie before application of the catalytic active component) has a bimodal pore radius distribution, preferably the median of a pore class 1 of 30 to 200 nm and the median of a pore class 2 of 2 to 25 nm, and wherein particularly preferably the median of a pore class 1 of 40 to 80 nm and the median e in P recre lk 2 of 5 to 20 nm be carrying, in particular measured by means of mercury porosimetry. The pores of the pore class 1 are preferably also used as transport pores during the catalyst preparation, so that the pores of the pore class 2 can be filled during the preparation by means of dry impregnation (incipient wetness) with the solvent containing cerium compounds. The pores of the pore class 1 are preferably also used as Transport pores during the HCl gas phase oxidation, so that the pores of the pore class 2 also supplied with sufficient feed gases and product gases are removed.

In a preferred embodiment, the novel catalyst material is characterized in that the catalyst support in the uncoated state (ie before application of the catalytic active component) has a surface area of from 30 to 250 m ² / g, preferably from 50 to 100 m ² / g, in particular measured the method of nitrogen adsorption with evaluation according to BET.

Particular preference is given to using a novel ZrC catalyst support which is specified as follows:

Specific surface area in the range of 55 m ² / g (nitrogen adsorption, evaluation according to BET)

• Bimodal pore radius distribution, where a pore class 1 (transport pores) has a median in the range of 60 nm and a pore class 2 (fine pores) has a median in the range of 16 nm (mercury porosimetry)

Pore volume in the range of 0.27 cmVg (mercury porosimetry) Bulk density in the range of 1280 kg / m ³

Particular preference is given to using a new ZrO ₂ catalyst support which is specified as follows:

Specific surface area in the range of 85 m ² / g (nitrogen adsorption, evaluation according to BET) Bimodal pore radius distribution, wherein a pore class 1 (transport pores) has a median in the range of 60 nm and a pore class 2 (fine pores) has a median in the range of 8 nm has (mercury porosimetry)

Pore volume in the range of 0.29 cmVg (mercury porosimetry)

• Bulk density in the range of 1160 kg / m ³ (measured in a stand cylinder with DN100 and 350 mm height)

In a preferred embodiment, the novel catalyst material is characterized in that the carrier component zirconium dioxide is at least 90% by weight, preferably at least 99% by weight, in the monoclinic crystal form, in particular estimated by X-ray diffraction. In a preferred embodiment, the new catalyst material is characterized in that the content of cerium is 1 to 20 wt .-%, preferably 3 to 15 wt .-% and particularly preferably 7 to 10 wt .-%.

In a preferred embodiment, the new catalyst material is characterized in that the oxide compounds of the cerium are the exclusive catalytic active components on the catalyst support.

Preferred oxide compounds of the cerium are Ce (III) oxide (Ce 2 O 3) and cerium (IV) oxide (CeO 2). Under conditions of HCl gas phase oxidation, Ce-Cl structures (Ce-chlorides) and also O-Ce-Cl structures (Ce-oxychlorides) are to be expected at least on the surface. In a preferred embodiment, the novel catalyst material is characterized in that the catalyst material is obtained by applying a cerium compound in particular from the following series: cerium nitrate, acetate or chloride in solution to the support by means of dry impregnation and subsequently drying and impregnating the impregnated support calcination at higher temperature. The coatings with catalytically active oxide compounds of cerium in the context of the invention are preferably obtainable by a process which comprises first applying a particularly aqueous solution or suspension of a cerium compound, preferably cerium nitrate, acetate or chloride, to the catalyst support so that the solution is particularly Preferably, the catalytic active component, ie, the oxide compound of the cerium, alternatively by Auf- and co-Auffällverfahren, and ion exchange and gas phase coating (CVD , PVD) are applied to the carrier.

After application of the cerium compound, a drying step is generally carried out. The drying step is preferably carried out at a temperature of 50 to 150 ° C, more preferably at 70 to 120 ° C. The drying time is preferably 10 minutes to 6 hours. The catalysts may be dried under normal pressure or preferably at reduced pressure, more preferably 50 to 500 mbar (5 to 50 kPa), most preferably around 100 mbar (10 kPa). Drying at reduced pressure is advantageous in order to be able to fill pores with a small diameter <40 nm in the carrier better with the preferably aqueous solution in the first step of drying.

After drying, a calcining step is generally carried out. It is preferred to calcine at a temperature of 600 to 1100 ° C, more preferably at 700 to 1000 ° C, most preferably at 850 to 950 ° C. The calcination takes place in particular in an oxygen containing atmosphere, more preferably under air. The calcination time is preferably 30 minutes to 24 hours.

The uncalcined precursor of the new catalyst can also be calcined in the reactor for the HC1 gas phase oxidation itself or particularly preferably under reaction conditions.

Preferably, the temperature is changed from one reaction zone to the next reaction zone. Preferably, the catalyst activity is changed from one reaction zone to the next reaction zone. Particularly preferably, both measures are combined. Suitable reactor concepts are described for example in EP 1 170 250 Bl and JP 2004099388 A. An activity and / or temperature profiling can help to control the position and strength of the hotspot.

Preferably, the average reaction temperature of the new catalyst for the purpose of HCl gas phase oxidation is 300-600 ° C, more preferably 350-500 ° C. Significantly below 300 ° C, the activity of the new catalyst is very low, well above 600 ° C are typically used as construction materials nickel alloys and unalloyed nickel is not long-term stability against the corrosive reaction conditions.

Preferably, the exit temperature of the new catalyst for the purpose of HCl gas phase oxidation is at most 450 ° C, more preferably at most 420 ° C. A reduced outlet temperature may be advantageous because of the then more favorable equilibrium of the exothermic HCl gas phase oxidation. Preferably, the O2 / HCl ratio is equal to or greater than 0.75 in each part of the bed containing the new catalyst. From an O2 / HCI ratio equal to or greater than 0.75, the activity of the new catalyst remains longer than when the O2 / HCI ratio is lower.

Preferably, the temperature is raised in a reaction zone when the catalyst deactivates. The initial activity of the new catalyst is particularly preferably characterized by a treatment with a higher O 2 / HCl ratio than under normal conditions of HCl gas phase oxidation, preferably at least twice as high, or under approximately HCl-free conditions (HCl / C ratio = 0 ), eg in air, partly to completely restored. Most preferably, this treatment is carried out for up to 5 hours under otherwise typical HCl gas phase oxidation temperatures. The novel catalyst is preferably combined with a separately supported ruthenium catalyst, the ruthenium catalyst being in the form of low-temperature complement, particularly preferably in the temperature range of 200-400 ° C., and the new catalyst as high-temperature complement, particularly preferably in the temperature range of 300-600 ° C. is used. Both types of catalysts are arranged in different reaction zones. Preferably, as already described above, the new catalyst composition is used in the catalytic process known as the Deacon process. Here, hydrogen chloride is oxidized with oxygen in an exothermic equilibrium reaction to chlorine, whereby water vapor is obtained. The usual reaction pressure is 1 to 25 bar, preferably 1, 2 to 20 bar, more preferably 1.5 to 17 bar, most preferably 2 to 15 bar. Since it is an equilibrium reaction, it is expedient to use oxygen in excess of stoichiometric amounts of hydrogen chloride. For example, a two- to four-fold excess of oxygen is customary. Since no loss of selectivity is to be feared, it may be economically advantageous to work at relatively high pressure and, accordingly, longer residence time than normal pressure.

A further subject of the invention is therefore a process for the thermocatalytic production of chlorine from hydrogen chloride and oxygen-containing gas, characterized in that a novel catalyst material described here is used as the catalyst. The invention also provides the use of the novel catalyst material as a catalyst in the thermocatalytic production of chlorine from hydrogen chloride and an oxygen-containing gas.

The catalytic hydrogen chloride oxidation may preferably be adiabatic or isothermal or approximately isothermal, batchwise, but preferably continuously or as a fixed or fixed bed process, preferably as a fixed bed process, more preferably adiabatically at 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 particularly preferably 2.0 to 15 bar are performed.

A preferred method is characterized in that the gas phase oxidation is operated isothermally in at least one reactor.

An alternative preferred method is characterized in that the gas phase oxidation is operated in an adiabatic reaction cascade, which consists of at least two cascaded adiabatically operated reaction stages with intermediate cooling.

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 multiple stages. In adiabatic, isothermal or nearly isothermal process control, but preferably in adiabatic process control, it is also possible to use a plurality of, in particular 2 to 10, preferably 2 to 6, series-connected reactors with intermediate cooling. The hydrogen chloride can either be completely together with the oxygen in front of the first reactor or distributed over the various reactors. This series connection of individual reactors can also be combined in one apparatus.

In a preferred embodiment, the novel catalyst is used for the purpose of HC1 gas phase oxidation in an adiabatic reaction cascade, which consists of at least two successive stages with intermediate cooling. Preferably, the adiabatic reaction cascade comprises 3 to 7 stages including respective intermediate cooling of the reaction gases. Most preferably, not all of the HCl is added before the first stage but distributed over the individual stages in each case before the respective catalyst bed or, more preferably, before the respective intermediate cooling. In a preferred embodiment, the new catalyst is used for the purpose of HC1 gas phase oxidation in an isothermal reactor, particularly preferably in only one isothermal reactor, in particular in only one tube bundle reactor in the flow direction of the feed gases. The shell-and-tube reactor is preferably subdivided into 2 to 10 reaction zones in the flow direction of the feed gases, more preferably into 2 to 5 reaction zones. In a preferred embodiment, the temperature of a reaction zone is controlled by surrounding cooling chambers in which a cooling medium flows and dissipates the heat of reaction. A suitable shell-and-tube reactor is discussed in SUMITOMO KAGAKU 2010-11 by Hiroyuki ANDO, Youhei UCHIDA, Kohei SEKI, Carlos KNAPP, Norihito OMOTO and Masahiro KTNOSHITA.

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 with arbitrary shapes, preference being given to tablets, rings, cylinders, stars, carriage wheels or spheres, particular preference being given to rings, cylinders, spheres or star strands as molds. Very particularly preferred is the spherical shape. The size of the shaped catalyst body, for example. Diameter at balls or maximum major extent is on average in particular 0.5 to 7 mm, more preferably 0.8 to 5 mm. In a preferred variant of the novel process, the cerium-containing catalyst material is combined with a separately supported ruthenium or ruthenium-containing catalyst, wherein the ruthenium catalyst as low temperature, preferably in the temperature range of 200 to 400 ° C and the cerium-containing catalyst material as Hochtemperaturkomplement, preferably in Temperature range of 300 to 600 ° C, is used.

Particularly preferably, both different types of catalyst are arranged in different reaction zones.

The conversion of hydrogen chloride in the single-pass HCl oxidation may preferably be limited to 15 to 90%, preferably 40 to 90%, particularly preferably 70 to 90%. After conversion, unreacted hydrogen chloride can be partly or completely recycled to the catalytic hydrogen chloride oxidation. The volume ratio of oxygen to hydrogen chloride at the reactor inlet is preferably 1: 2 to 20: 1, preferably 2: 1 to 8: 1, more preferably 2: 1 to 5: 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 of isocyanate distillation columns.

In a further step, 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 of water vapor formed can be carried out by condensing off aqueous sodium salt from the product gas stream of the 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

When comparing catalysts on a laboratory scale, sieve fractions are preferably used to directly measure the intrinsic activity of the catalyst and not have to take into account the influence of different shape dimensions with different influence on the mass transport. According to current doctrine, the reactor diameter should preferably be at least 10 times as large as the main extent of the particles of the catalyst material in order to neglect the influence of edge effects. Accordingly, when using sieve fractions, the laboratory reactors can preferably be kept small.

In order not to allow the pressure loss to increase disproportionately, moldings having a primary expansion of the particles of the catalyst material of at least 0.5 mm, more preferably of at least 1 mm, would be used in a fixed bed reactor on a production scale.

In addition, examples which have been characterized according to the invention have been carried out with sieve fractions, but it is to be understood that these inventive catalysts are always used in the process according to the invention as corresponding shaped bodies having a main extent of the particles of the catalyst material of at least 0.5 mm, more preferably of at least 1 mm would.

The key figures and results from the following examples are summarized in a table according to the last example.

Example 1 (according to the invention)

A ZrC catalyst support (manufacturer: Saint-Gobain NorPro, type: SZ 31 163, extrusions of 3 - 4 mm diameter and 4 - 6 mm length) in monoclinic structure with the following specifications (before mortar) was used: · Specific surface area of 55 m ² / g (nitrogen adsorption, evaluation according to BET)

• Bimodal pore radius distribution, with a pore class 1 (transport pores) having a median of 60 nm and a pore class e 2 (fine pores) having a median of 16 nm (mercury porosimetry)

• Pore volume of 0.27 cm ³ / g (mercury porosimetry) · Bulk density of 1280 kg / m ³ (measured in a stand cylinder with DN100 and 350 mm height) This ZrC catalyst support (SZ 3 1 163) was crushed with a mortar and classified into sieve fractions. 1 g of the sieve fraction 100-250 μιη was dried for 2 h at 160 ° C and 10 kPa. 50 g of cerium (III) nitrate hexahydrate was dissolved in 42 g of deionized water. 0.08 ml of the cerium (III) nitrate solution prepared in this way was initially charged with a quantity of deionized water which was sufficient for filling the entire pore volume in a rim cup and 1 g of the dried sieve fraction (100-250 μmol) of the ZrC catalyst support stirred in until the solution was completely absorbed (dry impregnation method). The impregnated ZrC catalyst support was then dried for 5 h at 80 ° C and 10 kPa and then calcined in air in a muffle furnace. For this purpose, the temperature in the muffle furnace was linearly increased within 5 h from 30 ° C to 900 ° C and held at 900 ° C for 5 h. Thereafter, the muffle furnace was linearly cooled from 900 ° C to 30 ° C within 5 h. The supported amount of cerium corresponds to a proportion of 3 wt .-% based on the calcined catalyst, wherein the catalyst components are calculated as CeC and ZrÜ2. 0.25 g of the thus prepared catalyst were diluted with 1 g Spheri glass (quartz glass, 500-800 μιη), placed in a fixed bed in a quartz reaction tube (inner diameter 8 mm) and at 430 ° C with a gas mixture of 1 L / h (Standard STP conditions) hydrogen chloride, 4 L / h (STP) oxygen and 5 L / h nitrogen (STP). The quartz reaction tube was heated by an electrically heated oven. After 2 hours, the product gas stream was passed for 30 minutes into 30% by weight potassium iodide solution. The resulting iodine was then back titrated with 0, 1 N thiosulfate standard solution to determine the amount of chlorine introduced. A chlorination rate (space-time yield = RZA) of 0.51 kg / ccKK-h (based on the catalyst mass) or 0.68 kg / cc / LREACTOR-h (based on the catalyst-filled reactor volume) was measured.

Example 2 (according to the invention)

There was prepared 1 g of a catalyst according to Example 1, wherein the supported amount of cerium was adjusted to a content of 5 wt .-% based on the calcined catalyst. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 0.92 kgci2 / kgKAh or 1.25 kgci2 / LREAKTO-h was measured.

Example 3 (according to the invention)

There was prepared 1 g of a catalyst according to Example 1, wherein the supported amount of cerium adjusted to a proportion of 7 wt .-% based on the calcined catalyst has been. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 1.17 kgci2 / kgKArh or 1.62 kgci2 LREAKTO - h was measured.

The catalysts based on undoped ZrC as carrier material have the best space-time yields (1.6-2.0 kg.sup.2 of LREAKTO-h) given sufficient Ce charges (Examples 3-6). Up to a loading of 7-10 wt .-%, based on the catalyst mass space-time yield of these particularly preferred CeC / ZrC catalysts (active component / carrier) increases approximately linearly with the cerium content. At a loading of 10-20 wt .-%, based on the catalyst mass space-time yield remains approximately constant, the ZrC catalyst carrier is saturated with active component.

Example 4 (according to the invention)

There was prepared 1 g of a catalyst according to Example 1, wherein the supported amount of cerium was adjusted to a proportion of 10 wt .-% based on the calcined catalyst. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 1.27 kgci2 / kgKArh or 1.82 kgci2 / LREACTOR-h was measured.

Example 5 (according to the invention)

There was prepared 1 g of a catalyst according to Example 1, wherein the supported amount of cerium was adjusted to a proportion of 15 wt .-% based on the calcined catalyst. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 1.28 kgci2 / kgKArh or 1.93 kgci2 LREACTOR h was measured.

Example 6 (according to the invention)

There was prepared 1 g of a catalyst according to Example 1, wherein the supported amount of cerium was adjusted to a content of 20% by weight based on the calcined catalyst. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 1.25 kgci2 / kgKArh or 1.98 kgci2 LREACTOR h was measured. Example 7 (according to the invention)

There were prepared 5 g of a catalyst according to Example 1, wherein (1) the ZrC catalyst support was not crushed before impregnation with the cerium nitrate solution, was accordingly used as an extrudate (3-4 mm in diameter and 4-6 mm in length) in which (2) the catalyst carrier extrudates loaded with cerium were only ground after calcining and classified to sieve fractions, of which the 100-250 μm sieve fraction was used in the testing and where (3) the supported amount of cerium amounted to 7 Wt .-% based on the calcined catalyst was adjusted. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 1.16 kgci2 / kgKAh or 1.61 kgci2 / LREAKTO-h was measured.

With Examples 7-8 it is shown that a similarly good space-time yield is achieved in the catalyst preparation by means of direct impregnation of the catalyst support molded body, as in the catalyst preparation by impregnation of the catalyst support sieve fractions. Catalyst support moldings are advantageously used to minimize the pressure loss in a preferred fixed bed in the HCl gas phase oxidation.

Example 8 (according to the invention)

There were prepared 5 g of a catalyst according to Example 7, wherein the supported amount of cerium was adjusted to a proportion of 10 wt .-% based on the calcined catalyst. The catalyst was tested according to Example 7. A chloroformation rate (RZA) of 1.14 kgci2 / kgKAh or 1.63 kgci2 / LREAKTO-h was measured.

Example 9 (Comparative Example)

ZrC catalyst support according to Example 1 (SZ 31 163) was crushed with a mortar and classified in sieve fractions, of which the 100-250 μιη sieve fraction was used in the testing. The ZrC catalyst support was tested according to the catalyst in Example 1. A chlorination rate (RZA) of 0.00 kgci2 kgKATh or 0.00 kgci2 / LREAKTO-h was measured. Consequently, ZrC carriers without the active component CeC are suitable only as carriers and not as active components. Example 10 (according to the invention)

A ZrC catalyst support (manufacturer: Saint-Gobain NorPro, type: SZ 31 164, extrusions of 3 - 4 mm in diameter and 4 - 6 mm in length) in monocrystalline structure with the following specifications (before mortar) was used: · Specific surface area of 85 m ² / g (nitrogen adsorption, evaluation according to BET)

• Bimodal pore radius distribution, where a pore class 1 (transport pores) has a median of 60 nm and a pore class 2 (F inp oren) has a median of 8 nm (mercury porosimetry)

• pore volume of 0.29 cm ³ / g (mercury porosimetry) · bulk density of 1160 kg / m ³ (measured in a stand cylinder with DN100 and 350 mm height)

This ZrC catalyst support (SZ 31 164) was pretreated according to Example 1 (crushed, classified, dried) and then used to produce 1 g of a catalyst according to Example 1, wherein the supported amount of cerium in a proportion of 3 wt. -% was adjusted based on the calcined catalyst. The catalyst was tested according to Example 1. A chlorination rate (RZA) of 0.51 kgci2 / kgKAT-h or 0.61 kgci2 LREAKTO ^■ h was measured.

Example 11 (According to the Invention) 1 g of a catalyst according to Example 10 was prepared, the supported amount of cerium being adjusted to a content of 5% by weight, based on the calcined catalyst. The catalyst was tested according to Example 10. A chloroformation rate (RZA) of 0.66 kgci2 / kgKAh or 0.81 kgci2 / LREAKTO-h was measured.

Example 12 (according to the invention)

There was prepared 1 g of a catalyst according to Example 10, wherein the supported amount of cerium was adjusted to a content of 7 wt .-% based on the calcined catalyst. The catalyst was tested according to Example 10. A chloroformation rate (RZA) of 0.78 kgci2 / kgKAh or 0.99 kgci2 / LREAKTO-h was measured. The catalysts based on undoped ZrC as support material have the best space-time yields at sufficient Ce loadings (Ex 12-15) (1, 0-1, 7 kgci2 / LREAKTO ^■ h). Up to a loading of 7-10 wt .-%, based on the catalyst mass space-time yield of these particularly preferred CeC / ZrC catalysts (active component / carrier) increases approximately linearly with the cerium content. At a loading of 10-20 wt .-%, based on the catalyst mass space-time yield remains approximately constant, the ZrC catalyst carrier is saturated with active component.

Example 13 (according to the invention)

There was prepared 1 g of a catalyst according to Example 10, wherein the supported amount of cerium was adjusted to a proportion of 10 wt .-% based on the calcined catalyst. The catalyst was tested according to Example 10. A chlorination rate (RZA) of 1.21 kgci2 / kgKArh or 1.58 kgci2 / LREAKTOR-h was measured.

Example 14 (According to the Invention) 1 g of a catalyst according to Example 10 was prepared, the supported amount of cerium being adjusted to a proportion of 15% by weight, based on the calcined catalyst. The catalyst was tested according to Example 10. A chloroformation rate (RZA) of 1.28 kgci2 / kgKArh or 1.76 kgci2 / LREACTOR-h was measured.

Example 15 (according to the invention)

There was prepared 1 g of a catalyst according to Example 10, wherein the supported amount of cerium was adjusted to a content of 20% by weight based on the calcined catalyst. The catalyst was tested according to Example 10. A chlorination rate (RZA) of 1.16 kgci2 / kgKArh or 1.66 kgci2 LREACTOR h was measured.

Example 16 (according to the invention)

There were prepared 5 g of a catalyst according to Example 10, wherein (1) the ZrCh catalyst carrier was not crushed before impregnation with the cerium nitrate solution, was thus used as an extrudate (3-4 mm in diameter and 4-6 mm in length) , wherein (2) the cerium-loaded catalyst support extrudates were only ground after calcination and classified to screen fractions, of which the 100-250 μιη sieve fraction used in the testing and wherein (3) the supported amount of cerium was adjusted to a content of 7% by weight based on the calcined catalyst. The catalyst was tested according to Example 10. A chloroformation rate (RZA) of 0.75 kgci2 kgKATh or 0.94 kgci2 / LREAKTO-h was measured. Examples 16-17 show that a similarly good space-time yield is achieved in the catalyst preparation by means of direct impregnation of the catalyst support molded bodies, as in the catalyst preparation by means of impregnation of the catalyst support sieve fractions. Catalyst support moldings are advantageously used to minimize the pressure loss in a preferred fixed bed in the HCl gas phase oxidation.

Example 17 (according to the invention)

There were prepared 5 g of a catalyst according to Example 15, wherein the supported amount of cerium was adjusted to a proportion of 10 wt .-% based on the calcined catalyst. The catalyst was tested according to Example 15. A chloroformation rate (RZA) of 0.94 kgci2 / kgKAh or 1.22 kgci2 / LREAKTO-h was measured.

Example 18 (comparative example)

ZrC catalyst carrier according to Example 1 (SZ 31 164) was crushed with a mortar and classified in sieve fractions, of which the 100-250 μιη sieve fraction was used in the testing. The ZrCh catalyst support was tested according to the catalyst in Example 10. A chlorination rate (RZA) of 0.00 kgci2 kgKATh or 0.00 kgci2 / LREAKTO-h was measured. Consequently, ZrCh carriers without the active component CeCh are suitable only as carriers and not as active components.

Example 19 (according to the invention)

A commercially available CeCh-doped ZrCh catalyst support (manufacturer: Saint-Gobain NorPro, type: SZ 61191, 3 mm diameter spheres) in a tetragonal structure with the following specifications (before mortar):

• 18% CeCh, remainder ZrCh · specific surface area of 110 m ² / g (nitrogen adsorption, evaluation according to BET) • Bimodal pore radius distribution, with a pore class 1 (transport pores) having a median of 1 50 nm and a pore class 2 (fine pores) having a median of 4 nm (mercury porosimetry)

• Pore volume of 0.25 cmVg (mercury porosimetry) · Bulk density of 1400 kg / m ³ (measured in a stand cylinder with DN 100 and 350 mm height)

This CeC-doped ZrC catalyst support (SZ 61 191) was crushed with a mortar and classified into sieve fractions. 1 g of the sieve fraction 100-250 μιη was dried for 5 h at 80 ° C and 10 kPa and then calcined in air in a muffle furnace. For this purpose, the temperature in the muffle furnace was linearly increased within 5 h from 30 ° C to 900 ° C and held at 900 ° C for 5 h. Thereafter, the muffle furnace was linearly cooled from 900 ° C to 30 ° C within 5 h. The amount of cerium corresponds to a fraction of 14.7% by weight based on the calcined catalyst, the catalyst components being calculated as CeC and ZrC.

A commercially available CeC-promoted ZrC catalyst support (SZ 61191) was crushed with a mortar and classified into sieve fractions, of which the 100-250 μιη sieve fraction was used in the testing. The ZrC catalyst support was tested according to the catalyst in Example 10. It was a chlorination rate (RZA) of 0.07 kgci2 / kgKAT-h and 0.08 kgci2 / LREAKTO -h measured.

The thus treated catalyst was tested according to Example 1. A chloroformation rate (RZA) of 0.92 kgci2 / kgKAh or 1.29 kgci2 / LREACTOR-h was measured. CeCh-doped ZrC has a significant space-time yield compared to the best tested catalyst system (1.29 kgci2 / LREAKTO -h versus 1.82-1.98 kgci2 / LREACTOR-h (Examples 4-6)). Although in this case the active component was not applied separately, the cerium in this case, of course, is to be understood as an active component. The example is therefore also understood as being according to the invention.

Example 20 (Comparative Example)

A ZrC catalyst support (manufacturer: Saint-Gobain NorPro, type: SZ 61 156, 3 mm diameter spheres) in a tetragonal structure with the following specifications (before mortar) was used:

• 10% La ₂ O ₃ , remainder ZrC

Specific surface area of 120 m ² / g (nitrogen adsorption, evaluation according to BET) Bimodal pore radius distribution, with a pore class 1 (transport pores) having a median of 200 nm and a pore class 2 (fine pores) having a median of 5 nm (mercury porosimetry)

• Pore volume of 0.3 cm ³ / g (mercury porosimetry) · Bulk density of 1300 kg / m ³ (measured in a stand cylinder with DN100 and 350 mm height)

This ZrC catalyst support (SZ 61156) was pretreated according to Example 1 (mortared, classified, dried) and then used to produce 1 g of a catalyst according to Example 1, wherein the supported amount of cerium to a share of 7 wt. % based on the calcined catalyst and wherein the catalyst components are calculated as CeC and ZrC. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 0.09 kgci2 / kgKAT-h and 0.12 kgci2 / LREAKTOR-h was measured.

The La2Ü3, which is often used as a structure stabilizer, appears to affect the particular interaction between CeC and ZrC. This comparative example shows that the inventors of DE '675 in Example 5 have selected an improper catalyst support. Only catalysts based on the carrier component ZrC, wherein the content of lanthanum in the form of La2Ü3 based on the calcined catalyst is less than 5% by weight and which most preferably are substantially free of lanthanum ingredients have a exceptionally high activity.

Example 21 (Comparative Example)

An AbOs catalyst support (manufacturer: Saint-Gobain NorPro, type: SA 6976, extrudates 2 to 3 mm in diameter and 4 to 6 mm in length) was used in γ-structure with the following specifications (before mortar): · Specific surface area of 250 m ² / g (nitrogen adsorption, evaluation according to BET)

• Bimodal pore radius distribution, where a pore class 1 (transport pores) has a median of 500 nm and a population class 2 (fine pores) has a median of 7 nm (mercury porosimetry)

• pore volume of 1.05 cmVg (mercury porosimetry) · bulk density of 460 kg / m ³ (measured in a stand cylinder with DN100 and 350 mm height) This AkCb catalyst support (SA 6976) was pretreated according to Example 1 (mortared, classified, dried) and then used to produce 1 g of a catalyst according to Example 1, wherein the supported amount of cerium to a share of 7 wt. % based on the calcined catalyst was adjusted and wherein the catalyst components are calculated as CeC and Al2O3. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 0.49 kgci ₂ / kgKAT-h and 0.24 kgci ₂ LREAKTO-h, respectively, was measured.

Example 22 (Comparative Example) 1 g of a catalyst according to Example 19 was prepared, wherein the supported amount of cerium was adjusted to a content of 12.5% by weight based on the calcined catalyst. The catalyst was tested according to Example 19. A chloroformation rate (RZA) of 0.86 kgci ₂ / kgKAh or 0.46 kgci ₂ / LREAKTO-h was measured.

Example 23 (comparative example)

An AbOs catalyst support (manufacturer: Saint-Gobain NorPro, type: SA 3177, extrusions of 3-4 mm in diameter and 4-6 mm in length) in mixed γ, α, Θ structure with the following specifications (before the mortars):

Specific surface area of 100 m ² / g (nitrogen adsorption, evaluation according to BET) Monomodal pore radius distribution with a median of 10 nm (mercury porosimetry)

• pore volume of 0.49 cm ³ / g (mercury porosimetry)

• Bulk density of 780 kg / m ³ (measured in a stand cylinder with DN100 and 350 mm height)

This AkCb catalyst support (SA 3177) was pretreated according to Example 1 (mortared, classified, dried) and then used to produce 1 g of a catalyst according to Example 1, wherein the supported amount of cerium to a share of 7 wt. % based on the calcined catalyst. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 0.47 kgci ₂ / kg CAT-h and 0.40 kgci ₂ / LREAKTO-h, respectively, was measured. Example 24 (comparative example)

A TiC catalyst carrier (manufacturer: Saint-Gobain NorPro, type: ST 31 1 19, extrudates 3-4 mm in diameter and 4-6 mm in length) was used in anatase structure with the following specifications (before mortar): · Specific Surface of 40 m ² / g (nitrogen adsorption, evaluation according to BET)

• Monomodal pore radius distribution with a median of 28 nm (mercury porosimetry)

• pore volume of 0.30 cm ³ / g (mercury porosimetry)

Bulk density of 1200 kg / m ³ (measured in a stand cylinder with DN100 and 350 mm height) This TiC catalyst support (ST 31 1 19) was pretreated (mortared, classified, dried) according to Example 1 and then used to 1 g of a catalyst according to Example 1, wherein the supported amount of cerium was adjusted to a proportion of 7 wt .-% based on the calcined catalyst. The catalyst was tested according to Example 1. A chloroformation rate (RZA) of 0.24 kgci ₂ / kgKAT-h and 0.32 kgci ₂ / LREAKTO-h, respectively, was measured.

Example 25 (Comparative Example)

A TiC-ZrC catalyst support (manufacturer: Saint-Gobain NorPro, type: ST 31140, extrusions of 3 - 4 mm diameter and 4 - 6 mm length) was used with the following specifications (before mortar):

• 40% T1O2 (anatase), remainder ZrC (monoclinic-tetragonal),

Specific surface area of 80 m ² / g (nitrogen adsorption, evaluation according to BET)

• Trimodal pore radius distribution, with a pore class 1 (transport pores) having a median of 121 nm, a pore class 2 having a median of 16 nm and a pore class 3 having a median of 11 nm (mercury porosimetry)

• pore volume of 0.46 cm ³ / g (mercury porosimetry)

• Bulk density of 815 kg / m ³ (measured in a stand cylinder with DN100 and 350 mm height) This Ti0 ₂ -Zr0 ₂ catalyst support (ST 31140) was pretreated according to Example 1 (mortared, classified, dried) and then used to produce 1 g of a catalyst according to Example 1, wherein the supported amount of cerium to a proportion of 7 wt .-% based on the calcined catalyst was adjusted. The catalyst was tested according to Example 1. A chlorination rate (RZA) of 0.14 kgci2 / kgKAT-hb0.13 kgci2LREAKTO ^■ h was measured.

Example 26 (according to the invention, temperature variation)

The catalyst from Example 3 was tested under otherwise identical conditions at 350, 370, 410 and 450 ° C: Chlorination rates (RZA) were obtained from:

350 ° C: 0,22 kgci2 / kgKArhb0,30 kgci2 / LREAKTOR-h

370 ° C: 0,44 kgci2 / kgKArhbzw.0,61 kgci2 / LREAKroR-h

410 ° C: 0,98 kgci2 / kgKArhbzw.1,36 kgci2LREAKTOR ^■ h

450 ° C: 1,80 kgci2 / kgKArhbzw.2,50kgci2 / LREAKTOR-h

The key figures and results from the examples given (with the exception of Ex. 26) are summarized in the table below.

Eg carrier identifier. Density prep. Test Ce RZA RZA

# kg / m ³ kg / m ³ wt% / ^h g / cm ³ h

1 Zr02 SZ31163 1327 SF SF 3 0.51 0.68

2 Zr02 SZ31163 1358 SF SF 5 0.92 1.25

3 Zr02 SZ31163 1388 SF SF 7 1.17 1.62

4 Zr02 SZ31163 1434 SF SF 10 1.27 1.82

5 Zr02 SZ31163 1509 SF SF 15 1.28 1.93

6 Zr02 SZ31163 1583 SF SF 20 1.25 1.98

7 Zr02 SZ31163 1388 Extrudate SF 7 1.16 1.61

8 Zr02 SZ31163 1434 Extrudate SF 10 1.14 1.63

9 (Cf.) Zr02 SZ31163 1280 SF SF 0 0.00 0.00

10 Zr02 SZ31164 1202 SF SF 3 0.51 0.61

11 Zr02 SZ31164 1230 SF SF 5 0.66 0.81

12 Zr02 SZ31164 1258 SF SF 7 0.78 0.99

13 Zr02 SZ31164 1300 SF SF 10 1.21 1.58

14 Zr02 SZ31164 1368 SF SF 15 1.28 1.76

15 Zr02 SZ31164 1435 SF SF 20 1.16 1.66

16 Zr02 SZ31164 1258 Extrudate SF 7 0.75 0.94

17 Zr02 SZ31164 1300 extrudate SF 10 0.94 1.22

18 (See) Zr02 SZ31164 1160 SF SF 0 0.00 0.00 19 (Zr-Ce) Ox SZ 61 191 1400 SF SF 14 0.92 1, 29

20 (Comp.) (Zr-La) Ox SZ 61 191 1410 SF SF 7 0.09 0.12

21 (Cf.) AI203 SA 6976 499 SF SF 7 0.49 0.24

22 (Cf.) AI203 SA 6976 531 SF SF 12.5 0.86 0.46

23 (Cf.) AI203 SA 3177 846 SF SF 7 0.47 0.40

24 (See) Ti02 SA 31 1 19 1302 SF SF 7 0.24 0.32

25 (See) (Ti-Zr) 02 SZ 31 140 884 SF SF 7 0.14 0.13

Conclusions:

ZrC carriers without the active component CeÜ2 have no activity (Examples 9 and 18) and are therefore suitable only as a carrier and not as an active component.

Doped with CeÜ2 ZrC (Example 19) has a compared to the best tested catalyst system considerable space-time yield to (1, 29 kgci2 LREAKTO ^■ h versus 1, 82-1, 98 kgci ₂ / L _Reacto -h (Examples 4- 6)). Although in this case the active component was not applied separately, the cerium in this case, of course, is to be understood as an active component. The example is also understood as being according to the invention.

AI2O3 (Ex 21-23), T1O2 (Ex 24), and Zr0 ₂ -Ti0 ₂ with low bulk density (Ex 25) are not optimal supports for CeC (0, 1 -0.5 kgci 2 LREAKTO ^■ h). For AI2O3, neither monomodal nor bimodal pore radius distributions are used. It is surprising that T1O2 as carrier for CeO 2 seems to be completely unsuitable. T1O2 is considered as one of the preferred support materials for the active component ruthenium dioxide in the HCl gas phase oxidation

The cited La2Ü3-doped ZrC (Ex 20) is also not an optimal support for CeC (0, 1 - 0.5 kgci2 / L EAKTO -h). The La2Ü3, which is often used as a structural stabilizer, seems to affect the particular interaction between CeÜ2 and ZrC. This comparative example shows that the inventors of DE '675 in Example 5 have selected an improper catalyst support. Only catalysts based on the carrier component ZrC, wherein the content of lanthanum in the form of La2Ü3 based on the calcined catalyst is less than 5 wt .-%, and most preferably are substantially free of lanthanum ingredients have an exceptionally high activity.

The catalysts based on undoped ZrC as carrier material have the best space-time yields at sufficient Ce loadings (Examples 3-6 and 12-15) (1.6-2.2 kg.sup.2 / LREAKTOR-h or 1, respectively) , 0-1, 7 kgci2 / LREAKTOR-II). Up to a loading of 7-10 wt .-%, based on the catalyst mass space-time yield of these two particularly preferred CeC / ZrC catalysts (active component / carrier) increases approximately linearly with the cerium content. At a Loading of 10-20 wt .-% remains based on the catalyst mass space-time yield is approximately constant, the ZrC catalyst carrier is saturated with active component.

At a comparable loading of 7 wt .-%, the best CeC / ZrC catalyst (1.28 kgci2 / kgKAT-h, Ex 5) has a 2.6 times higher based on the catalyst mass space-time yield than that best not new alternative catalyst (CeC / AhC: 0.49 kgci2 / kgKAh, Ex. 7). The active component cerium is therefore used much better in these novel CeC / ZrC catalysts than in other common carriers.

The best CeCVZrC catalyst (1.98 kg.sup.2 LREAKTO-h, Ex. 6) has a 4.3 time higher space-time yield relative to the reactor volume than the best non-inventive alternative catalyst (CeO.sub.1) -A.sub.2 C: O, 46 kgci2 / LREAKTO -h, ex. 24). As a result, the volume of the reactor is significantly better utilized in these novel CeCVZrC catalysts than in other common carriers. Of course, a reduced reactor volume also has a positive effect on the pressure loss and thus the electrical consumption.

Examples 7-8 and 16-17 show that a similarly good space-time yield is achieved in the catalyst preparation by means of direct impregnation of the catalyst support molded bodies, as in the catalyst preparation by means of impregnation of the catalyst support sieve fractions. Catalyst support moldings are advantageously used to minimize the pressure loss in a preferred fixed bed in the HCl gas phase oxidation.

Claims

Catalyst material of porous catalyst support and catalytic coating for a process for the thermo-catalytic production of chlorine from hydrogen chloride and oxygen-containing gas, wherein the catalyst material comprises at least: at least one oxide compound of cerium as catalytic active component and at least zirconium dioxide as a carrier component, characterized in that the content of lanthanum in Form of La2Ü3 based on the calcined catalyst less than 5 wt .-% is.

Catalyst material according to claim 1, characterized in that the calcined catalyst has a bulk density of at least 1000 kg / m ³ , preferably of at least 1200 kg / m ³ , more preferably of at least 1300 kg / m ³ , in particular measured in a cylinder with DN100 and 350 mm filling height, and w w w w ith the main extent of the particles of the catalyst material on average at least 0.5 mm, preferably at least 1 mm.

Catalyst material according to claim 1 or 2, characterized in that the catalyst support to at least 50 wt .-%, preferably at least 90 wt .-%, more preferably at least 99% by weight consists of zirconium dioxide.

Catalyst material according to one of claims 1 to 3, characterized in that the content of lanthanum in the form of La2Ü3 based on the calcined catalyst less than 3 wt .-%, preferably less than 2 wt .-%, more preferably less than 1 wt. %, and most preferably is substantially free of lanthanum constituents.

Catalyst material according to one of claims 1 to 4, characterized in that the porous catalyst support in the uncoated state has a bimodal pore radius distribution, wherein preferably the median of a pore class 1 of 30 to 200 nm and the median pore class 2 of 2 to 25 nm and wherein particularly preferred is the median of a pore class 1 of 40 to 80 nm and the median of a pore class 2 of 5 to 20 nm, in particular measured by means of mercury porosimetry.

Catalyst material according to one of claims 1 to 5, characterized in that the catalyst support in the uncoated state has a surface area of 30 to 250 m ² / g, preferably from 50 to 100 m ² / g, in particular measured by the nitrogen adsorption method with evaluation according to BET.

7. Catalyst material according to one of claims 1 to 6, characterized in that the carrier component is zirconium dioxide to at least 90 wt .-%, preferably at least 99% by weight in the monoclinic crystal form.

8. Catalyst material according to one of claims 1 to 7, characterized in that the content of cerium 1 to 20 wt .-%, preferably 3 to 15 wt .-% and particularly preferably 7 to 10 wt .-% is.

9. Catalyst material according to one of claims 1 to 8, characterized in that the oxide compounds of cerium, the exclusive catalytic active components on the

Catalyst supports are.

10. Catalyst material according to one of claims 1 to 9, characterized in that the oxide compounds of cerium are selected from the series: Ce (III) oxide (Ce203) and cerium (IV) oxide (Ce0 ₂ ). 11. Catalyst material according to one of claims 1 to 10, characterized in that the catalyst material is obtained by applying a cerium compound in particular from the series: cerium nitrate, acetate or chloride in solution by means of dry impregnation on the support and the impregnated support then dried and calcined at a higher temperature. 12. Use of the catalyst material according to any one of claims 1 to 11 as a catalyst in the thermo-catalytic production of chlorine from hydrogen chloride and an oxygen-containing gas.

13. A process for the thermocatalytic production of chlorine from hydrogen chloride and oxygen-containing gas, characterized in that a catalyst material according to one of claims 1 to 11 is used as the catalyst.

14. The method according to claim 13, characterized in that the gas phase oxidation is operated isothermally in at least one reactor.

15. The method according to claim 13, characterized in that the gas phase oxidation b in an adiabatic reaction cascade is operated, which consists of at least two cascaded adiabatically operated reaction stages with intermediate cooling.

16. The method according to any one of claims 13 to 15, characterized in that the cerium-containing catalyst material is combined with a separately supported ruthenium or ruthenium-containing catalyst, wherein the ruthenium catalyst as a low temperature, preferably in the temperature range of 200 to

400 ° C and the cerium-containing catalyst material as Hochtemperaturkomplement, preferably in the temperature range of 300 to 600 ° C, is used.

17. The method according to claim 16, characterized in that both different types of catalysts are arranged in different reaction zones.