BRPI0913160B1 - CATALYST FOR CATALYTIC OXIDATION OF GAS PHASE PHASE OF AROMATIC HYDROCARBONS FORMING ALDEIDS, CARBOXYLIC ACIDS AND / OR ANIDRIDS, ESPECIALLY ANXYRID OF PHYTHESIC ASPHYPHYLES, AS A PHYSICAL AND ANALYZED - Google Patents

Description

(54) Title: CATALYST FOR CATALYTIC OXIDATION OF GASEOUS PHASE

AROMATIC HYDROCARBONS FORMING ALDEHYDES, CARBOXYLIC ACIDS AND / OR CARBOXYLIC ACID ANIDIDES, ESPECIALLY ANTHYRID OF PHTHALIC ACID, AS WELL AS A METHOD FOR MANUFACTURING A CATALYST OF THIS TYPE (51) INT. B01J 23/68; C07B 41/08; C07C 51/265; B01J 23/00; B01J 8/04; B01J 8/06; B01J 23/22; B01J 27/198; B01J 27/199; B01J 35/00; B01J 37/02 (30) Unionist Priority: 08/29/2008 DE 10 2008 044 890.7 (73) Owner (s): JOSEF BREIMAIR (72) Inventor (s): JOSEF BREIMAIR

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CATALYST FOR CATALYTIC OXIDATION OF GAS PHASE OF AROMATIC HYDROCARBONS FORMING ALDEHYDES, CARBOXYLIC ACIDS AND / OR CARBOXYLIC ACID ANIDIDES, ESPECIALLY ANYTHED OF PHALYTIC ACID, AS WELL AS A METHOD OF METHOD OF METHOD FOR METHOD

A CATALYST OF THIS TYPE.

DESCRIPTION [0001] Catalytic gas-phase oxidation of aromatic hydrocarbons such as benzene, xylol, naphthalene, toluene or durol in fixed bed reactors, preferably tubular beam reactors, has long been known, and often described in the literature. In this way, they are manufactured, for

example, benzoic acid, maleic acid anhydride, anhydride anhydride in in acid phthalic, isophthalic acid, terephthalic acid and acid pyromelitic. [0002] | Therefore, in general, a mixture on one gas

containing molecular oxygen, for example air, and the hydrocarbon to be oxidized, for example o-xylol, is conducted through a so-called tubular beam reactor, in which a plurality of reaction tubes are arranged in parallel and in which there is a bed of a suitable catalyst.

[0003] To regulate temperature or to conduct the amount of heat that forms during the exothermic reaction, the tubes filled with catalyst are surrounded by a heat-carrying medium, for example, a molten salt.

[0004] Despite such temperature regulation or thermostatization, the formation of local maximum temperatures can occur in the catalyst bed, the so-called Hot-Spots (hot spots), which can cause unwanted effects, such as

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2/48 such as the total oxidation of the starting material or the formation of poorly separable by-products until the formation of a limited amount of starting material.

[0005] In order to avoid hot spots of this type, it was started in practice to have catalysts with different activity and chemical composition in layers superimposed on each other in the reaction tubes, and according to the technique in general, the catalyst presents in the range of the maximum level lower temperature activity and the catalyst layers that follow in the direction of the gas outlet show an increased activity.

[0006] In this case, the so-called shell-type catalysts have given good results, which in general are composed of a non-porous, inert carrier material, over which at least a thin layer of the catalytic action mass is formed, forming a shell.

[0007] For the catalytic properties of the catalysts in question the composition of the catalytic action mass plays a decisive role.

[0008] For the manufacture of phthalic acid anhydride from o-Xylol and / or naphthalene by oxidation in the gas phase with gases containing molecular oxygen in a fixed bed catalyst, a plurality of catalysts has been proposed in the past.

[0009] According to the state of the art, practically all industrially employed phthalic acid anhydride catalysts contain titanium dioxide compounds in the anatase and vanadium pentoxide modification as well as other components or promoters in small quantities in their catalytic action mass. mostly to improve activity, the

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3/48 reaction, yield, selectivity and long-term stability of the catalysts in question.

[00010] Such additives are, for example, cesium, antimony, phosphorus, boron, molybdenum, tungsten, tin, bismuth, silver, niobium, iron, potassium, rubidium, chromium and calcium.

[00011] Therefore, there is an effort through selective doping with different substances to further intensify the performance and stability capacity of PSA catalysts.

This means that in the course of time more complicated catalyst recipes and combinations of different catalysts are always developed to solve this problem.

[00012] So-called multi-layer catalysts are also increasingly used, which differ in terms of activity and selectivity due to their different composition from the active mass. In this case, several different catalysts are arranged in the overlapping layers in the catalyst bed, to perform different tasks according to the layer in the catalyst bed. In this case, it is basically the requirement, to safely control the exothermic reaction with high past amounts of starting substance, with both catalyst selectivity and stability.

[00013] Patent document EP A 21 325 describes catalysts for the manufacture of phthalic acid anhydride whose active mass contains 60 to 99% by weight of titanium dioxide, 1 to 40% by weight of vanadium pentoxide and, with respect to to the total amount of TiO ₂ and V ₂ O ₅ up to 2% by weight of phosphorus and up to 1.5% by weight of rubidium and / or cesium, the mass of catalytic action being

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4/48 applied in two layers on a carrier material. The inner layer in this case contains 0 to 2.0% by weight of phosphorus and does not contain rubidium and / or cesium and the outer layer 0 to 0.20% by weight of phosphorus and 0.02 to 1.5% by weight rubidium and / or cesium. The catalytic action mass of these catalysts may contain, apart from the mentioned components, yet other substances, for example, up to% by weight of an oxide of the metals molybdenum, tungsten, niobium, tin, silicon, antimony, hafnium. Steatite is used as inert carrier material.

[00014] Patent document EP A 286448 describes a method for the manufacture of phthalic acid anhydride, in which two different catalysts with similar content of titanium dioxide and vanadium pentoxide are employed. They differ basically in that a catalyst additionally contains 2 to% by weight of a cesium compound, especially cesium sulfate, but does not contain phosphorus, tin, antimony, bismuth, tungsten or molybdenum compounds and the second catalyst additionally contains 0.1 to 3.0% by weight of a compound of phosphorus, tin, antimony, bismuth, tungsten or molybdenum.

[00015] US patent document 4,864,036 relates to a catalyst for the manufacture of phthalic acid anhydride, which is manufactured in several stages. In this case, in the first stage a metal compound of the 6th subgroup, preferably a molybdenum or tungsten compound is applied in titanium dioxide in the anatase modification and then calcined. Then, in a second stage, a vanadium compound is added to the calcined pre-stage and this pre-stage is again calcined.

[00016] Patent document GB 1140264 refers to a

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5/48 oxidation catalyst for aromatic hydrocarbons forming carboxylic acids, which is composed of an inert, non-porous carrier material and a thick layer of 0.02 to 2 mm of active mass, which in turn is composed of 1 to 15 % V ₂ O ₅ and 85 to 99% titanium dioxide, with the vanadium content of the total catalyst being in the range of 0.05 to 3%. A catalyst is described in which the active mass, in addition to titanium dioxide and vanadium pentoxide, also contains 0.1 to 3% by weight of at least one metal oxide of the group of silver, iron, cobalt, nickel, chromium, molybdenum or tungsten.

[00017] Patent document EP 0447 267 describes a catalyst for the manufacture of phthalic acid anhydride which as a mass of catalytic action comprises the following: (A) 1 to 20% by weight of V ₂ O ₅ and 99 to 80% by weight of a titanium oxide in the anatase modification with a BET surface of 10 to 60m ² / g and (B), with respect to 100 parts by weight of this mixture (A), 0.05 to 1.2 parts by weight of the mixture minus one element of the group K, Cs, Rb and TI as oxide and 0.05 to 2 parts by weight of silver, calculated as silver oxide.

[00018] Patent document EP 0522 871 BI refers to a catalyst, which in addition to titanium dioxide and vanadium pentoxide also contains 0.01 to 1% by weight of niobium as niobium pentoxide, 0.05 to 2 % by weight of at least one element of the potassium, cesium, rubidium or thallium group as oxide, 0.2 to 1.2% by weight of phosphorus as P2O5, and 0.55 to 5.5% by weight of antimonoxide and

0.05 to 2% silver by weight as Ag2O, with a pentavalent antimony compound being used as the source for the antimony.

[00019] CN1108996 refers to a catalyst

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6/48 with two layers based on titanium dioxide V / 205 that additionally contains at least one rare earth compound and at least one oxide of the antimony, phosphorus, zinc and silver elements, with the closest layer at the gas inlet it also contains an alkali metal compound. Silver-vanadium oxide compounds with an atomic ratio of Ag: V <1 are known as silver bronze. The use of vanadium-silver bronze as an oxidation catalyst is generally known in the specialized literature.

[00020] DE 198 51 786 A1 describes a multimetal oxide from Ag ₃ . _b M _b V ₂ 0 _x * c H ₂ O, with a having a value of 0.3 to 1, 9, Mé a metal selected from the group Li, Na, K, Rb ₂ Cs

Ti, Mg, Ca, Sr, Ba, Cu, Zn, Cd, Pb, Cr, Au, AI, Fe, Co, Ni and / or Mo and b have a value from 0 to 0.5, where b is equal to or greater than 0.1. The use of the multimetal oxides in question is described as a precursor compound for the manufacture of pre-catalysts and catalysts for the gas phase oxidation of aromatic hydrocarbons.

[00021] WO 2005/092496 Al finally describes a catalyst for the manufacture of aldehydes, carboxylic acids and / or anhydrides of carboxylic acid, the active mass of which contains an A phase and a B phase in the form of three-dimensionally delimited areas, that phase A is a bronze of oxide and vanadium-silver and phase B is an oxide phase of mixing element based on titanium dioxide and vanadium pentoxide. The molar ratio of Ag: V in phase A is 0.15 to 0.95.

[00022] The catalysts described above, known in the state of the art with more different compounds from the active mass or do not reach selectivities, yields or satisfactory activities

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7/48 or have a very short service life or industrial manufacturing implies enormous effort or high costs.

[00023] For this reason, there is a continuing need for catalysts with selectivity and even better yields with past amount of raw material at the same time high and longer service life, which can be manufactured industrially at an acceptable cost-benefit ratio.

[00024] For this reason, it is the task of the present invention to develop an improved catalyst for the gas phase oxidation of aromatic hydrocarbons forming aldehydes, carboxylic acids and / or carboxylic acid anhydrides, especially forming phthalic acid anhydride, which results in the case of a high amount of raw material passed, in an improved selectivity with a longer useful life. In addition, the technical undertaking and financial expense for manufacturing on an industrial scale the catalyst should be kept as small as possible.

[00025] This task is solved with the characteristics of the claim 1. Preferred arrangements are the subject of the dependent claims, whose publication content is expressly incorporated in this description.

[00026] According to claim 1, a catalyst is claimed for the catalytic oxidation of the gas phase of aromatic hydrocarbons forming aldehydes, carboxylic acids and / or carboxylic acid anhydrides, especially forming phthalic acid anhydride, in which the active mass contains oxide vanadium, preferably vanadium pentoxide, titanium dioxide, preferably in anatase modification, and at least one

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8/48 silver mixing element oxide with defined elements, preferably vanadium and / or molybdenum and / or tungsten and / or niobium and / or antimony, and / or a vanadium mixing element oxide with defined elements, preferably bismuth and / or molybdenum and / or tungsten and / or antimony and / or niobium. In the manufacture of the catalyst, especially in the manufacture of a suspension of catalyst or powder mixture necessary for the coating of a carrier material, at least one oxide of silver and / or vanadium and / or at least mixture element is used a precursor compound, especially at least one multivalent precursor compound, at least one oxide of silver and / or vanadium mixing element as a source of raw material.

[00027] It has been surprisingly found that the use of mixing element oxides, preferably mixed metal oxides, silver with, for example, vanadium, molybdenum, tungsten, niobium and / or antimony, and / or the use of oxides of mixing element, preferably of mixed metal oxides, of vanadium with, for example, bismuth, molybdenum, tungsten, niobium and / or antimony, or its precursor compounds as a source of raw material in the manufacture of the catalyst suspension or in the manufacture of a powder mixture used for the coating process and / or as a component of the catalyst active mass in addition to the titanium dioxide and vanadium oxide components, also results in a significant increase in selectivity.

[00028] The reason, in this case, is not entirely clear, but it is assumed that the interaction of silver with the other catalytic action components such as the titanium dioxide / vanadium oxide monolayer is basically more effective and therefore the action of the promoter

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9/48 itself of silver (the suppression of the total oxidation of organic raw material forming carbon oxides) brings better results.

[00029] In the art the use of silver as a component of the active mass is often described. In this case, silver was used as a raw material source for the catalyst suspension, in addition to silver oxide, also corresponding salts such as silver nitrate, silver sulfate, silver halide, silver sulfide, silver phosphate , silver salts of organic acids, silver hydroxide, ammonium salts of silver and and amine complex of silver. Most of these raw material sources are transformed into silver oxide during the heating of the catalyst and are therefore present in the active mass as silver oxide, while for example silver phosphate and silver halide remain unchanged in the active mass and in the non-heat treatment are transformed into silver oxide.

[00030] An essential aspect of the catalysts according to the invention is that conventional catalysts contain at least titanium dioxide and vanadium oxide in the active mass, as additional doping agents oxides of silver with vanadium and / or other elements vanadium and / or mixing element oxides with other defined elements, with at least one silver and / or vanadium mixing element oxide and / or a corresponding precursor compound of at least one of these mixing element compounds it is added in the manufacture of the catalyst suspension or in the manufacture of a powder mixture used to coat the carrier material.

[00031] The invention furthermore expressly refers

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10/48 also to a method for the manufacture of the catalysts described here according to the invention, in which a suspension of catalyst or a mixture of the different components is manufactured, which contains at least titanium dioxide in the anatase modification and a compound of vanadium and at least one silver and / or vanadium mixed element oxide with defined elements or a corresponding precursor compound of at least one of these mixing element oxides as a source of raw material.

[00032] All components are advantageously amalgamated in the aqueous medium with each other and then applied over a ceramic carrier material using a spray method (preferably fluidized bed method or drum cleaning method). The mixture element oxide phase of silver and / or vanadium or its mixture element precursor compounds are advantageously added in this case directly to the catalyst suspension with the main components, titanium dioxide and vanadium oxide, as well as other promoters and are generally present as spatially separated phases forming a phase composed of titanium dioxide and vanadium oxide. Therefore, all components of the catalyst suspension form a unitary phase, which in addition to the titanium dioxide and vanadium oxide components, also contains the mixing element oxides in question and optionally other components.

[00033] But other systems are also possible, in which different successive layers with a different chemical compound are applied over the inert carrier material and at least one layer contains at least one oxide element.

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11/48 mixture of silver and / or vanadium with defined elements. In this case, the individual coating layers of a catalyst according to the invention can also be composed of a combination of compounds according to the invention and compounds not according to the invention.

[00034] Likewise the mixed element oxides in question can also be used individually or in combination with other compounds in one or more coating layer (s), which do not contain titanium dioxide and / or vanadium oxide in the active mass.

[00035] According to the invention, therefore, catalysts or pre-stages can be made for the production and manufacture of catalysts for partial gas phase oxidation of aromatic hydrocarbons with gas containing molar oxygen, which are structured from a material inert carrier, non-porous and with one or more layers applied over it in a shell shape, with at least one of these layers containing 0.01 to 15% by weight, in relation to the total weight of these layers, one or more of the oxides of aforementioned mixing element or its precursor compounds.

[00036] In addition, a concrete process control is claimed for the manufacture of carboxylic acids and / or carboxylic acid anhydrides through partial oxidation of aromatic hydrocarbons in the gas phase with a gas containing molar oxygen at a higher temperature in a catalyst, whose active mass is applied over a shell-like inert carrier material, a control characterized by the fact that a shell catalyst is obtained whose catalytic action mass with

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12/48 in relation to its total weight, it contains 0.01 to 15% by weight of an oxide of silver mixing element with vanadium and / or of an oxide of silver mixing element with other defined elements and / or

0.01 to 10% by weight of an elemental oxide of vanadium with bismuth and / or an elemental oxide of vanadium with other defined elements and at the same time titanium dioxide in the anatase modification and a vanadium compound (preferably

V2O5), with the mixture element oxide compound (s) or precursor compound (s) already being used for the manufacture of the catalyst suspension and / or powder mixture, from which the active mass is formed after coating the carrier material by means of heat treatment.

[00037] In this case, at least one shell catalyst not according to the invention, which in its active mass contains as essential components vanadium oxide, especially vanadium pentoxide, and titanium dioxide, especially in the anatase modification, but does not contain none of the mixing element oxides mentioned below or their precursor compounds, may be present or absent in the oxidation of aromatic hydrocarbons forming carboxylic acids and / or carboxylic acid anhydrides and be used in a combined bed (ie, in a mixture of a or several layers) together with one or more catalysts according to the invention, previously described.

[00038] Preferably a gaseous flow is introduced in this case over a bed of at least two layers of catalysts, the catalyst placed closest to the gas inlet containing a catalyst according to the invention and the catalyst bed placed downstream. contains at least one catalyst,

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13/48 whose catalytic action mass contains vanadium oxide and titanium dioxide in the anatase modification, but does not contain oxide of silver mixing element with elements such as vanadium, molybdenum, tungsten, niobium, antimony and / or also does not contain oxide of the vanadium mixture element with elements such as bismuth, molybdenum, tungsten, niobium, antimony.

[00039] However, catalyst beds composed of at least two layers can also be used, with all catalyst layers containing catalysts according to the invention. In this case, the catalysts according to the invention employed can be differentiated by the type and quantity of the mixing element oxides in the active mass.

[00040] Preferably, at least a part, especially preferably all layers of catalyst employed in the catalyst bed including the catalysts of

a deal with The invention, should to present a mass of action catalytic, what contains 1 to 40 % by weight of oxide vanadium (calculated as V ₂ O ₅ ), 50 to 99 % by weight of dioxide titanium (calculated as TiO ₂ ), up to 1% in weight of a compound of metal

alkaline (preferably a cesium compound, calculated as an alkali metal), up to 1.5% by weight of a phosphorus compound (calculated as P) and up to 10% by weight of an antimony compound (calculated as Sb ₂ O ₃ ) .

[00041] According to an especially advantageous arrangement, the catalysts according to the invention preferably contain

0.01 to 15% by weight of at least one oxide of silver mixing element with at least one element of the group vanadium, niobium, tantalum, titanium, zirconium, chromium, molybdenum, tungsten, cerium,

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14/48 lanthanum, aluminum, boron, manganese, iron, cobalt, nickel, copper, zinc, gold, cadmium, tin, lead, bismuth, antimony, arsenic, hafnium, rhenium, ruthenium, rhodium and palladium, and / or preferably 0 , 01 to 10% by weight of at least one oxide of vanadium mixing element with at least one element of the group bismuth, antimony, niobium, tantalum, titanium, zirconium, chromium, molybdenum, tungsten, cerium, marsh, aluminum, boron , manganese, iron, cobalt, nickel, copper, zinc, gold, cadmium, tin, lead, arsenic, hafnium, rhenium, ruthenium, rhodium and palladium.

[00042] The element oxide content of silver with defined elements, especially with, for example, vanadium and / or tungsten and / or molybdenum and / or niobium and / or antimony, in the active mass of catalysts in a preferred embodiment it is in a range of 0.01 to 15% by weight, in a most preferred embodiment in a range of 0.01 to 10% by weight and in an especially preferred embodiment in a range of 0.01 to 5% by weight. The oxide content of mixing element of vanadium with defined elements (with the exception of silver, see previous information regarding an oxide of mixing element of silver with vanadium), especially with, for example, tungsten and / or molybdenum and / or niobium and / or antimony, the active mass of catalysts is in an embodiment in a range of 0.01 to 10% by weight, in an especially preferred embodiment in a range of 0.01 to 5% in weight.

[00043] In a preferred embodiment, a catalyst according to the invention is used in a first catalyst layer placed closer to the gas outlet, being the layer with the maximum Hot Spot. In the direction of

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At least one other catalyst layer is placed at the gas outlet, which generally has a higher activity than the first catalyst layer and is generally a catalyst corresponding to the state of the art. The catalyst according to the invention in this case contains at least one silver mixing element oxide, preferably silver vanadate, and preferably one vanadium mixing element oxide, preferably bismuth vanadate.

[00044] It also proved to be advantageous when in a multi-layer catalyst system with at least one layer upstream of the Hot Spot catalyst layer towards the gas inlet, at least one of the catalyst layers from the gas inlet to including the maximum hot spot layer, contains a catalyst according to the invention and conventional catalysts corresponding to the prior art and / or catalysts according to the invention with a reduced content of claimed mixing element oxides are used for subsequent layers. in the active mass.

[00045] In another especially preferred embodiment, at least one of the catalyst layers, which is found before the layer with the maximum Hot Spot, contains a silver mixing element oxide, preferably a silver mixing element oxide with molybdenum and / or tungsten and especially preferably a silver oxide mixing element, while the layer with the maximum Hot Spot and the layers placed downstream do not contain silver mixing element oxide. The maximum Hot Spot layer advantageously contains an elemental oxide mixture of vanadium and bismuth. The layers of

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16/48 subsequent catalysts in the gas outlet direction of the Hot Spot catalyst layer preferably correspond to the state of the art and do not, in general, contain catalysts according to the invention.

[00046] In an especially preferred embodiment of the catalyst the compounds AgVO ₃ and / or Ag ₂ Mo0 ₄ and / or Ag ₂ WO ₄ and / or BiVO ₄ are employed in the manufacture of the catalyst suspension and / or are present in the mass active catalysts.

[00047] In this case, it is important to select the content of the mixing element oxides that act as promoters neither as low nor as high. If the oxide content of the silver mixing element is too low, the selectivity-enhancing action will not be entirely successful, whereas with a very high content of [silver mixing element oxides, there will be an increased activity which causes a reduced selectivity due to an increased total oxidation in relation to CO and CO ₂ .

[00048] In addition, it is advantageous to use the catalysts according to the invention, especially in the catalyst layers placed closer in relation to the gas inlet, even the layer with the maximum Hot Spot, since otherwise all the intensifying action of selectivity will not more can be obtained, since an essential part of the raw material had already been transformed.

[00049] A very high oxide content of mixed elements of bismuth also acts negatively on the selectivity of the catalyst and at the same time can cause the increasing formation of by-products, which cause a worsened color stability of the desired phthalic acid anhydride product. A content

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17/48 very low oxides of bismuth mixing element in counterpart does not lead to a significant increase in selectivity.

[00050] By combining at least two, but especially advantageously, several layers of catalyst in one bed, of which at least one layer of catalyst contains a catalyst according to the invention, a very good yield can be obtained in total higher than in the case with the single use of multi-layer catalyst systems with catalysts not according to the invention.

[00051] In this case, according to the state of the art in many cases the catalyst activity gradually increases from the first layer of catalyst, used in the gas inlet to the last layer placed the closest in relation to the gas inlet.

The selectivity adjustment can be done through different methods known to the person skilled in the art. For example, there is an increase in catalyst activity in the layers from the gas inlet to the gas outlet through a gradual reduction of the alkali metal content in the active mass, an increase in the average surface

BET of the titanium dioxide employed or an increase in the active mass content in the total weight of the catalyst. A combination of different measures can also be used to adjust selectivity.

[00052] The catalysts according to the invention advantageously contain in the active mass at least one type of titanium dioxide in the anatase modification, at least one compound of vanadium (preferably V2O5), at least one oxide of silver mixing element and / or vanadium and optionally an antimony compound, an alkali compound and / or a phosphorus compound.

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18/48 [00053] The total content of titanium dioxide is 50 to 99% by weight in the active mass of the catalysts according to the invention and especially preferably 80 to 99% by weight.

[00054] In this case, only one type of titanium dioxide can be used in the anatase modification with different physical properties or also a mixture of several titanium oxides with different physical properties for the manufacture of the catalyst suspension and / or the active mass of the catalysts.

[00055] The average BET surface of the titanium dioxide of the catalysts according to the invention in the case of one or more types of titanium dioxide is in this case advantageously 10-60 m ² / g and especially advantageously 12-30 m ² / g, while the BET surface of the individual types is in the range of 3 to 300 m ² / g.

[00056] The average BET surface of the titanium dioxide used is calculated from the quantity and type of surface

BET of the types individually employed. In this case, preferably at least one type of titanium dioxide is used, whose average particle size is in the range of 0.3 to 0.8 pm.

[00057] The vanadium oxide content in the active mass (calculated as V2O5) is in a preferred range of 1 to 40% by weight and in an especially preferred embodiment in a range of 1 to 20% by weight.

[00058] For the manufacture of the catalysts according to the invention, the raw material sources of vanadium pentoxide and / or vanadium oxalate are used. However, in principle, other vanadium compounds are also suitable, such as, for example, ammonium metavanadate, polyivanadinic acid, among others, or a mixture of different sources.

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19/48 [00059] In general, these precursor compounds or raw material sources of vanadium during the heat treatment of the catalyst or during the heating of the catalyst are transformed into vanadium pentoxide in the reactor in the presence of molecular oxygen so that in the active mass vanadium is basically present in the pentavalent oxidation stage.

[00060] Depending on the layer of the respective catalyst according to the invention in the catalyst bed, the active masses of these catalysts, in addition to titanium oxide, vanadium oxide, have one or more oxides of silver and / or vanadium mixing element as well as additionally one or more elements of the alkali metal group.

[00061] These are generally added as salts (for example sulphates, carbonates, nitrates, phosphates) to the catalyst suspension and are reacted during heating of the catalyst to form the corresponding oxides or remain unchanged in the active mass (after heat treatment of the catalyst ).

[00062] Alkali metal compounds are used to increase activity and at the same time improve the selectivity of catalysts.

[00063] In one embodiment, the alkali metal in the active mass is located in one by weight and especially preferably in one by weight. A soluble catalyst suspension, such as cesium sulphate, is used in a particular way.

[00064] The catalysts accordingly contain advantageously, especially in the preferred mass, the range of advantageous compounds with the active

O content in 0 to 1.0 σ. 0 0 to 0.6 σ. 0 O for The

cesium invention, layer of

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20/48 Hot Spot catalyst, also an antimony compound as a component of the active mass to improve thermal stability. The antimony content in the active mass is advantageously in a range of 0 to 10% by weight (calculated as Sb2O3) and especially preferably in a range of 0 to 5% by weight, depending on the catalyst layer in question in the bed complete with catalyst and depending on the heat treatment of the catalyst in question in the respective layer.

[00065] As starting substances for the manufacture of the catalyst suspension or a powder mixture of the catalysts according to the invention necessary for the coating of the carrier material, different antimony compounds can be used, such as antimony salts or antimony oxides at different stages of oxidation.

[00066] In a preferred embodiment of the catalyst according to the invention, antimony-111 oxide is employed in the manufacture of the catalyst suspension.

[00067] Also the catalysts according to the invention can contain a phosphorus compound in the catalytic action mass or a phosphorus compound can be added as a source of raw material in the manufacture of the catalyst suspension or a powder mixture used for the coating of the carrier material. In an especially advantageous embodiment of the catalysts according to the invention, the phosphorus content of the active mass, in this case, lies in a range of 0 to 1.5% by weight (calculated as

P) · [00068] Especially advantageously the phosphorus content increases from the gas inlet to the gas outlet in

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21/48 multi-layer catalysts with one or more catalysts according to the invention or with one or more catalysts not according to the invention in a bed. As a source of raw material for the catalysts according to the invention, dihydrogen ammonium phosphate is preferably suitable.

[00069] Furthermore, in the active masses of the catalysts according to the invention, a plurality of other compounds may be present in small amounts, which as promoters reduce or increase the activity and / or interfere with the selectivity of the catalyst.

[00070] In the literature it is described that for the increase of activity or for the weakening or even the suppression of the so-called hot spots (Hot Spots) it was decided in the technique, to employ multi-layer catalysts, which are placed in layers, especially with several layers of caliper overlapping each other in the catalyst bed, in the state of the art in general the least active catalyst is the closest to the gas inlet and the activity increases from layer to layer towards the outlet of gas.

[00071] The catalysts of the individual layers present, in this case, different chemical compositions, which in turn produce different activities and selectivities.

[00072] For the invention it is sufficient if in a multi-layer catalyst system at least one layer contains a catalyst according to the invention, which contains at least one of the mixing element oxides in question.

[00073] Preferably, mainly the first layer, which is the closest to the gas inlet and which

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22/48 is also the layer with the maximum Hot Spot, it contains a catalyst according to the invention. It is especially advantageous if all the layers in the catalyst bed, starting from the gas inlet up to and including the layer with the maximum Hot Spot, contain catalysts according to the invention. Der Gehalt und die [00074] The type of mixing element oxides, for example, silver, can in this case vary in the different layers in

question. In this case , is vatanj oso adapt also the rest dough compositions active according with your layer in bed catalyst. [00075] In an form of concretization preferred

mainly the layer with the maximum local temperature level contains an oxide of silver mixing element and / or an oxide of mixing element of bismuth with vanadium.

[00076] Especially the use of a combination of the mixing element oxides of AgVO ₃ and BiVO ₄ in the layer with the maximum Hot Spot revealed an intensifying action of selectivity in the catalysts according to the invention.

[00077] It has been surprisingly found that it is especially advantageous if at least one of the active masses of the catalyst layers, which are upstream in the direction of the gas inlet before the maximum hot spot layer, has a reduced antimony content in relation to the maximum Hot Spot layer.

[00078] In another advantageous embodiment of a catalyst with several layers in one or several beds, at least one layer of catalyst that is upstream of the layer of catalyst Hot Spot, contains at least one oxide of silver mixing element with the elements indicated, especially

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23/48 advantageously with vanadium and / or molybdenum and / or tungsten.

[00079] In a special embodiment of the catalysts according to the invention, at least one of the layers from the gas inlet to the layer with maximum Hot Spot contains a silver mixing element oxide, especially a mixing element oxide of silver with vanadium and / or molybdenum and / or tungsten, while the layer with the maximum Hot Spot preferably contains a vanadium mixing element oxide, especially a bismuth vanadium mixing element oxide.

[00080] In another especially preferred embodiment all layers from the gas inlet to the layer with

Maximum Hot Spot contains a silver mixing element oxide and only the layer with the Maximum Hot Spot an adiocnal mixing element oxide of vanadium with bismuth.

[00081] Especially advantageous is the use of multi-core mixture element oxides or their precursor compounds as a source in the manufacture of the catalyst suspension or a powder mixture used for the coating of the carrier material.

[00082] In addition, oxides of silver mixing element can also be used to manufacture the catalyst suspension and / or active mass, which have a lower or higher atomic ratio to silver than in the case of AgVO ₃ .

Depending on which atomic ratio of the elements is present in the mixture element oxide in question, the amount of the mixture element oxide and / or its precursor compounds in the catalyst suspension or powder mixture used for the coating may be adjusted, in order to obtain an ideal content of

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24/48 silver in the active mass of the finished catalyst.

[00083] It is advantageous if the described mixing element oxide phase or its precursor compound is already formed, before it is added to the catalyst suspension or to the powder mixture used to coat the carrier material. But one or more corresponding precursor compounds from the catalyst suspension or powder mixture can also be added, which are reacted during heat treatment to form the corresponding mixing element oxides.

[00084] As previously described, not only oxides of mixing element present in the molar ratio of whole numbers, of silver with other elements and / or their precursor compounds can be used as a source of raw material in the manufacture of the catalyst suspension or be present in the active mass of the catalysts according to the invention, but also oxides of two or multiple-core silver mixing element with a large atomic deficit or excess of silver.

Depending on the general formula of the mixing element oxides or their silver component, the content of the mixing element oxide in question should be increased or reduced in the catalyst suspension and / or in the active mass.

[00085] The dual or multi-core mixing element oxides of silver are described by the general formula

Ag _x M _y N _z O _n (Formula I) according to claim 11.

[00086] In the mixed metal oxide of the formula I x it especially preferably has a value of 0.1 to 5, the value of the variable y is preferably 0 to 0.3.

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25/48 [00087] Especially preferred are mixed metal oxides of the following general formula:

Ag _x N ₂ O _n where

Ag = silver x = a value of 0.1 to 5

N = an element of the group vanadium, molybdenum, tungsten, niobium, antimony z = 1 n = is a number, which is determined by the valence and frequency of the elements other than oxygen in formula I.

[00088] In principle, it is possible and covered by the invention that in the manufacture of the catalyst suspension one or more precursor compounds of the mixture element oxides in question and / or their starting compounds and the catalysts according to the invention with the mixing element oxides in question being formed first in the reactor by calcination at elevated temperature or during the heating period of the catalyst in the reactor.

[00089] In a preferred embodiment of the catalyst especially the use of the mixing element oxides

AgVO ₃ , Ag ₂ Mo0 ₄ , Ag ₂ WO ₄ and / or oxides of mixing elements of these elements with other atomic reasons, produces an improvement of the catalysts.

[00090] It was then found that the addition of oxides of silver mixing element with preferably, for example,

vanadium, tungsten and molybdenum, suspension of catalyst to instead of silver compounds from core single leads to an considerable improvement of selectivity, in Comparation The catalysts that don't feature silver on pasta active and / or to

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26/48 to which silver is added as an oxide (AgO or Ag2O) or as a salt (nitrate, phosphate, sulfate, chloride, ammonium salt, salt of an organic acid) or also as a hydroxide or as an amine complex in the catalyst suspension or is present in the active mass.

It is assumed that silver can participate in the form of a mixing element oxide or a mixing element compound more intensely in the catalytic process than in the form of a salt or a single-core oxide.

[00091] By way of example, but not in a restrictive manner, this point mentions the compound AgVO ₃ as a component of the catalysts according to the invention, which is used as an addition in the manufacture of the catalyst suspension or active mass, being that the active mass contains at least still titanium dioxide in the anatase modification and a vanadium compound. Preferably, the catalyst according to the invention further contains at least one compound of an element of the first main group. Depending on the layer of the catalyst according to the invention, the catalyst according to the invention also contains an antimony compound, especially Sb2O3 in the active mass and possibly a phosphorus compound. It has surprisingly been found that in multi-layer catalysts it is especially advantageous with regard to increasing selectivity, to employ at least one oxide of silver mixing element with vanadium and / or tungsten and / or molybdenum or its precursor compounds in the manufacture of the catalyst being that the catalyst according to the invention is advantageously used in one or more layers of catalyst from the gas inlet to the layer with the maximum Hot Spot.

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27/48 [00092] In an especially preferred embodiment, one or more or all of the aforementioned catalyst layers range from the gas inlet to the Hot layer

Maximum spot an oxide of silver mixing element with vanadium and / or tungsten and / or molybdenum from 0.01% by weight to 15% by weight, especially from 0.01 to 10.0% by weight and especially preferably from 0 , 01 to 5% by weight in the active mass.

[00093] In a special embodiment of the catalyst according to the invention, in the case of silver-vanadium mixture element oxides of compounds with a molar ratio of Ag: V of 1: 1, especially element oxide mixing AgVO3. In this case, it is not a so-called pratavanium-bronze, in which the atomic ratio of Ag: V by definition is less than 1: 1.

[00094] In addition, it has been found that the use of oxides of mixing element of vanadium with bismuth, molybdenum, tungsten, antimony, arsenic, lead, tin, zinc, copper, nickel, cobalt, iron, manganese, chromium, niobium , zirconium, titanium, gold, rhenium, lanthanum, cerium, tantalum, rhenium as a source of raw material in the manufacture of catalyst and / or as a component of the active mass produces an improvement in selectivity.

[00095] Especially the use of bismuth vanadate as a source of raw material in the manufacture of the catalyst suspension or as a component of the active mass causes an improvement in selectivity. In this case, it is advantageous if the catalysts according to the invention contain BiVO ₄ as a component of the active mass, especially in one or more layers from the gas inlet to the layer with the maximum Hot Spot.

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28/48 [00096] The catalysts according to the invention may in this case, in addition to titanium dioxide and vanadium oxide contain at least one oxide of the silver mixing element with one or more of the elements mentioned and at least an oxide of vanadium mixing element with one or more of the elements cited. In a preferred embodiment for the manufacture of the suspension of the catalysts according to the invention, silver vanadate and bismuth vanadate are used and / or are present side by side in the active mass of the catalysts.

[00097] Depending on the layer of the catalysts according to the invention in the catalyst bed, the catalysts according to the invention additionally further contain at least one alkali metal compound, preferably a cesium compound, an antimony compound, preferably oxide oxide. antimony-I I 1 and optionally a phosphorus compound.

[00098] In this case, not only oxides of the vanadium mixing element present in the atomic ratio of whole number with other elements or their precursor compounds can be used as a source of raw material in the manufacture of the catalyst suspension or present in the active mass of the catalysts of according to the invention, but also oxides of a mixture element of two or multiple nuclei of vanadium with a large deficit or excess of vanadium. Depending on the general formula of the mixture element oxides or their percentage of vanadium, the content of the mixture element oxide in the catalyst suspension and / or in the active mass must be reduced or increased.

[00099] Vanadium two- or multiple-core mixed element oxides are described by the general formula below

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29/48 according to claim 12:

M ₃ N _b V _c 0 _d (formula II) [000100] For the catalysts according to the invention, so-called shell catalysts are advantageously considered, in which the catalytic action mass is applied in shell form in one or more layers on an inert carrier material generally under reaction conditions, such as porcelain, magnesium oxide, tin dioxide, silicon carbide, cerium silicate, magnesium silicate (soapstone), zirconium silicate, aluminum oxide, Quartz , or mixtures of these carrier materials. In the technique, mainly carrier materials made of steatite or silicon carbide have given good results.

[000101] For the manufacture of shell catalysts of this type, in general, a solution containing aqueous and / or organic solvent or suspension (here called the catalyst suspension) of the active mass components and / or their precursor compounds is applied on the carrier material in the fluidized bed method (DE-A

2106796) with high temperature, until the desired percentage of active mass in the total weight of the catalyst is obtained. The coating of the inert, non-porous carrier material with the components of active mass or its precursor compounds such as suspension or powder mixture can also be done in a tablet coating device heated to high temperatures.

[000102] As during the spraying of the catalyst suspension with the components present therein of active mass and / or their precursor compounds in the tablet coating device or during the coating of the inert carrier material

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30/48 In the fluidized bed, high losses of the catalyst suspension may occur in part by nebulizing the catalyst suspension and / or by abrasion of the already coated carrier material, it was started in the art to add organic binders, preferably copolymers, to the catalyst suspension. advantageously in the form of an aqueous dispersion of vinyl acetate / vinyl laurate, vinyl acetate / acrylate, styrene / acrylate, vinyl acetate / maleate as well as vinyl acetate / ethylene, among others, and in general amounts of binder are used 10-20% by weight, based on the solids content of the catalyst suspension. In case of addition of one of the mentioned binders, the coating temperature is advantageously in the range of 50-450 ° C. The binders used decompose after the introduction of the catalyst in the reactor in most cases already during the heating of the reactor to service temperature or later during the startup of the catalyst and are removed completely from the catalyst.

[000103] The components of catalytic action remaining on the carrier material as a thin shell are called active mass. The components of the active mass can be partially differentiated from the components used in the suspension of catalyst or sources of raw material or precursor compounds, since these are partly chemically reacted through the heat treatment of the catalyst and most often transformed into the corresponding metal oxides .

[000104] It was then surprisingly found that the performance capacity of the catalysts does not depend exclusively on the composition and quantity of the active mass

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31/48 (catalytic action compounds present after heating or quenching) of the catalysts, but also the raw material sources used in the suspension of catalyst or powder mixture used to coat the carrier material have a significant influence on selectivity , activity and useful life of the catalysts.

[000105] The invention further relates to a method for the manufacture of aldehydes, carboxylic acids and / or carboxylic acid anhydrides, in which a gas stream, which contains an aromatic hydrocarbon and comprises a gas containing molecular oxygen, is placed in contact with a catalyst defined above under high temperature.

[000106] The mixture element oxides used as a source of raw material for the catalyst suspension can be manufactured in a different way and be placed in the catalyst suspension as an isolated compound or directly as a reaction mixture. In the same way, corresponding precursor compounds of the mixing element oxides of the catalyst suspension can be added. In this case, these are advantageously multi-core mixing element compounds or mixing element oxide compounds, which generally have a crystal structure different from the corresponding heat-treated mixing element oxides and present in the active mass and that can still contain crystal water.

[000107] For the manufacture of the mixing element oxides used in the catalysts according to the invention and / or their precursor compounds, in many cases the reaction of a solution of a metal compound is advantageously suitable

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32/48 with a suspension of a metal oxide under high temperatures in an aqueous or non-aqueous solvent. Thus, for example, a silver-vanadium oxide used for the catalysts according to the invention can be advantageously manufactured in that the silver nitrate is reacted in aqueous solution under high temperatures with vanadium pentoxide in the corresponding desired atomic ratios. The reaction mixture in this case formed with the mixed metal compound present therein can be added to the catalyst suspension or the corresponding mixed metal compound can also be isolated and optionally be heat treated.

[000108] As a solvent, in addition to water, polar organic solvents such as polyols, polyethers or amines also serve. The reaction of a metal oxide or several metal oxides (such as vanadium pentoxide and molybdenum trioxide) with a silver compound and optionally with another compound (such as a phosphorus compound) can be carried out in general at room temperature or at elevated temperature.

Preferably, the reaction is carried out at temperatures of 50 to 100 ° C and lasts according to the starting substances employed and reaction conditions 20 minutes to 5 days.

[000109] The mixed metal compound thus formed can be isolated from the reaction mixture and optionally deposited until the next use or directly added as a suspension solution to the catalyst suspension, which further contains at least titanium dioxide and a vanadium compound . The mixed metal compound isolated and obtained through the reaction can also be subjected to a treatment prior to addition to the catalyst suspension.

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33/48 thermal under high temperatures to produce a rearrangement of the crystal structure and a removal of crystal water.

[000110] In the case of previous isolation of the mixed metal compound, this can be done by removing the suspension and drying the solid matter obtained by filtration, and drying can be done through different methods. Advantageously, the drying of the mixed metal suspension is carried out by spray drying or freeze drying.

[000111] Alternatively to the solution reaction, mixed metal compounds can also be produced by smelting, for example, so that different finely mixed metal oxide powders are reacted in a solid matter reaction under high temperatures of 400 to 800 ° C.

[000112] The components of the catalyst suspension are generally used in the form of oxides and / or in the form of compounds, for example, salts, which turn into oxides during heating in the presence of oxygen. However, they can also be added to metal salts such as phosphates or halides, to the catalyst suspension, which remain unchanged in the catalyst active mass even after a heat treatment.

[000113] The manufacture of the catalysts according to the invention is done in general through a pre-stage of the ready catalyst, which can be deposited as such. In this case, it is an inert ceramic carrier material, on which the primary materials used in the catalyst suspension are applied by means of a dispersion process and are advantageously fixed using an organic binder.

[000114] The active catalyst in general is formed through

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34/48 heat treatment of this pre-stage or during the heating of the catalyst in the reactor. In this case, and in general the mixed metal compounds used are transformed into the corresponding metal oxides. For example, vanadium oxalate is compound and transformed into V ₂ O ₅ . Also, other compounds obtained in the catalyst suspension can be transformed during heating, into their oxidic compounds. Thus, it can be assumed that hydrogen ammonium phosphate is transformed into P ₂ O ₅ and is present as such in the active mass. In the event that mixed aqueous metal oxides are manufactured and used as a source of raw material in the manufacture of the catalyst suspension, one should generally start from the fact that they lose crystal water during the heat treatment of the catalyst and optionally change its structure crystal.

[000115] The transformation of the raw material fonts used in the catalyst suspension occurs preferably at temperatures of 200 to 500 ° C and especially preferably in the range of 300 to 500 ° C.

[000116] The shape of the inert carrier material is not decisive for the performance capacity of the catalysts according to the invention, however in the state of the art spheres or rings have proved to be advantageous solid bodies.

[000117] The layer thickness of the active mass or the sum of the layer thicknesses of the shells containing the active mass is in general 20-400 pm and varies according to the catalyst layer according to the invention in the catalyst bed .

[000118] It was also surprisingly found that in general there is no need for a spatial separation of the different

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35/48 components of the mixed metal oxide catalyst suspension used to obtain improved catalysts. All components used in the catalyst suspension are generally mixed or amalgamated with the corresponding mixed metal oxides and the mixed suspension is uniformly applied over the inert carrier material. However, catalysts are also possible, in which different catalyst suspensions are applied successively to the inert ceramic carrier material, at least one layer containing a catalyst according to the invention, thus forming an improved catalyst according to the invention. .

[000119] Furthermore, improved catalysts are possible, in which a catalyst suspension not according to the invention containing at least titanium dioxide, a vanadium compound and advantageously also an alkali metal compound, is first isolated and optionally thermally treated and then the powder formed in general is again mixed with a powder (advantageously in water), which was previously obtained from a catalyst suspension which is composed of at least titanium dioxide, a compound of vanadium and at least minus a mixed metal oxide or its precursor compound. This new catalyst suspension can be applied as a layer individually on an inert ceramic carrier material or, however, it can also be used in combination with other coating layers according or not according to the invention.

[000120] The catalysts according to the invention are generally used for the partial oxidation of the gas phase of aromatic hydrocarbons forming aldehydes, carboxylic acids

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36/48 and / or carboxylic acid anhydrides. In this case, these catalysts are mainly suitable for the oxidation of o-Xylol and / or naphthalene gas phase forming phthalic acid anhydride with a gas containing molecular oxygen.

[000121] The catalysts according to the invention can, as already mentioned, be used in a catalyst bed for this purpose, individually or in combination with other catalysts of different action, for example, catalysts of the prior art (vanadium pentoxide / anatase base without mixed metal oxide components).

[000122] In this case, the different catalysts according to or not according to the invention in general are used in separate catalyst beds, which are arranged in at least one catalyst bed. In this case, it is advantageous to use the catalysts according to the invention in the catalyst layers placed as close to the gas inlet as possible to the layer with the Hot

Maximum spot.

[000123] The use of the catalysts according to the invention in the catalyst layers subsequent to the layer with the maximum Hot Spot and catalyst layers placed closer in relation to the gas inlet has in effect a positive effect, but already an action much smaller positive with respect to

selectivity than O use of catalysts in a deal with The invention in relationship at layers of catalyst placed more next on input in gas. The catalysts in a deal with The invention and / or its catalysts precursors in a deal with The

invention are introduced into the reaction tubes of a layered reactor. The different layers can in this case be composed of

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37/48 catalysts according to the invention and not according to the invention.

[000124] It is also possible to employ in one layer a bed of a mixture made of at least one catalyst according to the invention and at least one catalyst not according to the invention and to use that bed individually or in combination with other layers of catalyst made of catalysts according to the invention and / or not according to the invention.

[000125] The reaction tubes are, in this case, thermostatized from the outside, which usually occurs through a molten salt, which bathes the tubes.

[000126] During the heating of the reactor with the reaction tubes recently filled with catalyst and / or in the case of the subsequent heat treatment of the catalyst, the properly active catalyst is formed from the catalyst pre-stage, in which the organic binder is removed by combustion and the respective raw material sources used in the catalyst suspension in general will become the corresponding oxidic compounds.

In addition, depending on the type of the mixed metal compounds and also their chemical composition and / or their crystalline structure may change.

[000127] Over a catalyst bed thermally treated in this way composed of at least one catalyst according to the invention the reaction gas is conducted at temperatures of 250-550 ° C, especially under 330 to 500 ° C and under an overpressure of in general 0.1 to 2.5 bar, preferably 0.3 to 1.5 bar, and the spatial speed in general is 1000 to 5000 h (-1).

[000128] The reaction gas carried to the catalyst is in

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38/48 is generally generated by mixing a gas containing molecular oxygen, preferably air, which, in addition to oxygen, may also contain suitable reaction moderators or diluting agents such as steam, nitrogen and / or carbon dioxide, with the aromatic hydrocarbon oxidant, the gas containing molecular oxygen in general may contain from 1 to 100% by volume and especially preferably from 10 to 30% by volume of oxygen, 0 to 30% by volume of water vapor, preferably from 0 to 20% by volume of water vapor as well as from 0 to 50% by volume, preferably from 0 to 1% by volume of carbon dioxide, nitrogen residue. For the formation of the reaction gas, the gas containing molecular oxygen in general is mixed with 20 to 200 g each Nm ³ and especially preferably with 60 to 120 g each Nm ³ of the aromatic hydrocarbon to be oxidized.

[000129] In a preferred embodiment of the method for the partial oxidation of aromatic hydrocarbons forming aldehydes, carboxylic acids and / or carboxylic acid anhydrides, which is especially advantageous for the oxidation of o-Xylol and / or mothballs forming anhydride of phthalic acid, the aromatic hydrocarbon is first reacted in a bed of the catalyst according to the invention only partially forming a reaction mixture made of starting substance, intermediate products and final product and this mixture reacted with at least one other catalyst that can be also according to the invention or one can be a catalyst corresponding to the state of the art.

[000130] The reaction, however, can also be carried out with more than one reactor, each reactor being thermostatized

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39/48 at different reaction temperatures and at least contain a bed of catalyst with at least one layer of catalyst. For the method according to the invention it is sufficient if at least one of these reactors has a layer with a catalyst according to the invention.

[000131] For the manufacture of phthalic acid anhydride made of o-Xylol the partially reacted reaction gas contains, in addition to the desired product phthalic acid anhydride, after circulating in one or more layers of catalyst, also an essential amount of o-xylol unreacted and intermediate products such as o-tolylaldehyde and o-tolyl phthaline acid.

[000132] Then in general the product mixture is conducted without further separation on at least one other layer of catalyst, which differs in relation to its chemical composition and activity of the catalyst according to the invention to guarantee the complete reaction of the material raw material or the oxidation of suboxidation products to form phthalic acid anhydride.

[000133] In addition, it is possible to separate the unreacted o-xylol after circulating through the catalyst bed with the catalyst according to the invention before the reaction gas is conducted to one or more catalyst beds.

[000134] Such a variant, however, can be carried out technically only with relatively great effort.

[000135] For this reason it is preferable that the reaction mixture passes through several layers of catalyst without separating starting substances or intermediate products, with at least one of these layers of catalyst, preferably the layer (s) placed more near the gas inlet, contain a

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40/48 bed of a catalyst according to the invention.

[000136] In general, the catalyst according to the invention is used together with at least another or several layers of catalyst, with at least one of the layers of catalyst placed from the gas inlet to the layer with the maximum Hot Spot contains a catalyst according to the invention, which in general is composed of 1 to 40% by weight of vanadium pentoxide, calculated as V2O5, 50 to 99% by weight of titanium dioxide, calculated as TiO ₂ , up to 1% in weight of an alkali metal compound, calculated as alkali metal, preferably cesium, up to 1.5% by weight of a phosphorus compound, calculated as

P, up to 10% by weight of an antimony compound, calculated as

Sb ₂ O ₃ and up to 15% by weight of at least one silver mixing element oxide with at least one of the elements described above and / or up to 10% by weight of a vanadium mixing element oxide with at least one of the elements previously described.

[000137] The catalysts used in combination in this case, which are generally used in layers, and which are closer to the gas outlet and follow after the layer with the maximum Hot Spot, are based at least on catalysts not in accordance with the invention based on titanium dioxide / V205, however it does not contain oxides of silver and / or vanadium mixing element. However, catalysts exclusively according to the invention can also be used in all layers. In this case, in general the catalysts differ in type and quantity of the mixed metal oxides present in the active mass.

[000138] Catalysts not according to the invention

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41/48 used in combination with the catalysts according to the prior art invention generally have a titanium dioxide content of 60-99% by weight, a vanadium content of 1 to% by weight, an alkali metal content up to 1% by weight, a phosphorus content up to 1.5% by weight and an antimony content up to 10% by weight.

[000139] Unaffected by the compositions described above, the active masses of the catalysts according to and / or not according to the invention may still contain small amounts of other oxidic compounds for the control of activity and selectivity.

Examples

Catalyst manufacture [000140] The different components of the catalyst suspension are successively placed as solutions and / or as a powder in the deionized water and the suspension formed is advantageously stirred for at least 12 hours. As raw material sources for the components present in the catalyst according to the invention, titanium dioxide is advantageously employed in the anatase modification, V2O5 or vanadyl oxalate, cesium sulfate, ammonium hydrogen phosphate, antimony trioxide, bismuth vanadate and vanadate silver, silver molybdate, silver tungstate and / or various other mixed metal oxides of silver and vanadium.

[000141] Then an organic binder is placed in the form of an aqueous dispersion of a vinylacetate copolymer in the aqueous catalyst suspension and the total suspension of approximately 20 to 25% is stirred for an additional 30 minutes.

[000142] Then a corresponding amount of

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42/48 aqueous suspension, which contains the active substance and / or its precursor compounds and the organic binder, is applied in the dispersion method on the inert carrier material (steatite rings 7x7x4 mm or 8x6x5 mm in size), up to a certain amount of the suspension with an adhesive content content is applied to the rings so that after calcination, the active mass shown in the examples results.

[000143] The active mass content (content of the catalytic action substances without binder) respectively refers to the percentage of the catalytic action mass in the total weight of the catalyst including the carrier material in the respective catalyst layer, determined after calcination for 4 hours under 400 ° C. [000144] The indicated phosphorus content refers to the amount added of a phosphorus compound during the manufacture of the catalyst suspension. It is known to the person skilled in the art that the effective phosphorus content may differ in the active mass, depending on how intensely the TiO _{2 used} is contaminated with phosphorus compounds.

Oxidation reaction [000145] In a tubular reactor with a reaction tube made of iron with an internal diameter of 25 mm and a length of 3.7 m, which is bathed in a salt bath, the multi catalyst system is introduced -layer, being that in the examples described the layer RI is located the closest to the gas inlet and the layer R4 or layer R-5 is located in the closest to the gas outlet.

[000146] In the reaction tube, a 2mm thermal sleeve with a built-in traction element was centrally arranged.

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43/48 for temperature measurement. Through the reaction tube, 4 Nm ³ of air with a charge of approx. 30 to 70 g- Xylol / Nm ³ in air at a salt bath temperature of 340-380 ° C.

[000147] For the determination of the catalytic performance data, the reaction gas leaving the reaction tube is conducted through an oil-cooled condenser, in which mainly the phthalic acid anhydride precipitates almost totally and the secondary products such as benzoic acid, maleic acid anhydride and phthalate precipitate only partially. The crude PSA precipitated in the condensers is melted by means of hot oil, collected, weighed and then the phthalic acid anhydride content is determined through GC analysis.

[000148] The gross PSA yield shown in the examples is calculated as follows:

Yield of crude PSA (% by weight) = (amount of crude PSA (g) x purity of crude PSA (%)) / (oXylol feed (g) x o-Xylol purity (%)).

[000149] The yield thus obtained from solid PSA is called gross PSA yield despite the deduction of secondary products present there, since pure PSA is generally a product obtained after heat treatment and distillation processing. This is also known to the person skilled in the art.

[000150] As the reaction of o-xylol in any case is practically 100%, the yield thus determined corresponds directly with the selectivity of the catalyst system.

Example 1 (comparative example): catalyst system A (4 layers)

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44/48

Composition in the layer 2a layer 3rd layer 4th layer % by weight (Hot spot) Length: 14 7cm 4 5 cm 7 0 cm 7 0 cm V205 5.0 7.7 8.5 15, 0 Sb203 2.5 2.2 2.4 0.5 BiV04 0.31 - - - Cs 0.37 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 Ti02 Rest a 100% Rest a 100% Rest a 100% Rest a 100% AM percentage 8.3 8.4 8.4 8.0

[000151] In the case of this catalyst system, it is a multi-layer system with four different layers. The individual beds of these comparative catalysts do not contain silver mixing element oxide.

[000152] In the case of a loading of 50 to 65g of o-Xylol per Nm ³ in the air and an amount of air of a total of 4.0 Nm ³ per hour and 344 to 347 ° C SBT the catalyst system was tested The described in example 1.

[000153] In this case an average crude PSA yield (with respect to 100% o-xylol purity) was obtained after the loading phase of 113.4% by weight and the phthalate content in the crude PSA was

0.01% by weight.

Example 2 (according to the invention): Catalyst system B (4 layers)

Composition in the layer 2a layer 3rd layer 4th layer % by weight (Hot spot) Length: 14 0cm 4 5 cm 70 cm 70 cm V205 5.0 7, 7 8, 5 15.0 Sb203 2, 5 2.2 2, 4 0, 5 BiV04 0.31 - - - AgV03 0.17 - - - Cs 0.40 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 Ti02 Rest a 100% Rest a 100% Rest a 100% Rest a 100% AM percentage 8.6 8, 4 8, 4 8, 0

[000154]

In the case of a loading of 58 to 63g of o-Xylol

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45/48 per Nm ³ in the air and an amount of air of in total 4.0 Nm ³ per hour and 346 at 352 ° C SBT the catalyst system B described in example 2 was tested. In this case, a yield was obtained of average crude PSA (with respect to 100% o-xylol purity) after the loading phase of 114.0% by weight and the phthalate content in the crude PSA was 0.06% by weight.

Example 3 (according to the invention): catalyst system C (4 layers)

Composition in the layer 2a layer 3rd layer 4th layer % by weight (Hot spot) Length: 14 0cm 4 5 cm 70 cm 70 cm V205 5.0 7, 7 8, 5 15.0 Sb203 2, 5 2.2 2, 4 0, 5 BiV04 0.31 - - - AgV03 0.34 - - - Cs 0.42 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 Ti02 Rest a 100% Rest a 100% Rest a 100% Rest a 100% AM percentage 8, 7 8, 4 8, 4 8, 0

[000155] In the case of a loading of 58 to 65g of o-Xylol per Nm ³ in the air and an amount of air in total of 4.0 Nm ³ per hour and 346 to 347 ° C SBT the catalyst system was tested C described in example 3. In this case, an average crude PSA yield (with respect to 100% o-xylol purity) was obtained after the loading phase of 115.3% by weight and the phthalate content in the crude PSA was 0.04% by weight.

Example 4 (according to the invention): catalyst system D (4 layers)

Composition in the layer 2a layer 3rd layer 4th layer % by weight (Hot spot) Length: 14 5 cm 4 5 cm 7 0 cm 7 0 cm V205 5.0 7.7 8.5 15, 0 Sb203 2.5 2.2 2.4 0.5 BiV04 0.31 - - - Ag2W04 0.39 - - -

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Cs 0.40 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 Ti02 Rest a 100% Rest a 100% Rest a 100% Rest a 100% AM percentage 8.7 8.4 8.4 8.0

[000156] In the case of loading 57 to 69g of o-Xylol per Nm ³ in the air and a total amount of air of 4.0 Nm ³ per hour and 346 to 348 ° C SBT the catalyst system was tested D described in example 4. In this case, an average crude PSA yield (with respect to 100% o-xylol purity) was obtained after the loading phase of 113.9% by weight and the phthalate content in the crude PSA it averaged 0.02% by weight.

Example 5 (according to the invention): catalyst system E (4 layers)

Composition in the layer 2a layer 3rd layer 4th layer % by weight (Hot Spot) 8x6x5mm 7x7x4mm 7x7x4mm 7x7x4mm Length: 140 cm 4 5 cm 7 0 cm 7 0 cm V205 5.0 7, 7 8.5 15, 0 Sb203 2.5 2.2 2.4 0.5 BiV04 0.31 - - - Ag2Mo04 0.16 - - - Cs 0.40 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 Ti02 Rest a Rest a Rest a Rest a 100% 100% 100% 100% AM percentage 8.6 8, 4 8.4 8.0

[000157] In the case of a loading of 52 to 62g of o-Xylol per Nm ³ in the air and an amount of air of a total of 4.0 Nm ³ per hour and 347 to 348 ° C SBT the catalyst system was tested It is described in example 5. In this case, an average yield of crude PSA (with respect to 100% o-xylol purity) was obtained after the loading phase of 114.2% by weight and the phthalate content in the crude PSA it averaged 0.01% by weight.

Example 6 (comparative example): catalyst system F (5 layers)

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Composition in the layer 2nd layer 3rd layer 4th layer 5th layer % by weight (Hot spot) Length: 4 5 cm 9 5 cm 50 cm 6 5 cm 7 0 cm V205 5.0 5.0 7.7 8.5 15, 0 Sb203 2.5 2.5 2.2 2.4 0.5 BiV04 0.31 0.31 - - - Cs 0.36 0.42 0.21 0.10 0.05 P 0.03 0.03 0.05 0.05 0.10 Ti02 Rest a Rest a Rest a Rest a Rest a 100% 100% 100% 100% 100% AM percentage 8.8 7.8 8.4 8.4 8.0

[000158] In the case of loading 58 to 61 of o-Xylol by

Nm ³ in the air and a total amount of air of 4 Nm ³ per hour and

350 to 354 ° C SBT the catalyst system F described in example 6 was tested. In this case, an average crude PSA yield was obtained

H (with respect to 100% o-xylol purity) of 113.1% by weight after the loading phase and the phthalate content in the raw PSA was

0.01% by weight.

Example 6 (according to the invention): catalyst system G (5 layers)

Composition in the layer 2nd layer 3rd layer 4th layer 5th layer % by weight (Hot spot) Length: 50 cm 9 Ocm 4 5 cm 7 Ocm 7 Ocm V205 4.0 5.0 7.7 8.5 15, 0 Sb203 0.2 2.5 2.2 2.4 0.5 BiV04 - 0.31 - - - AgV03 - 0.17 - - - Cs 0.28 0.40 0.21 0.10 0.05 P - 0.03 0.05 0.05 0.10 Ti02 Rest a Rest a Rest a Rest a Rest a 100% 100% 100% 100% 100% AM percentage 6.9 7.8 8.4 8.4 8.0

[000159] In the case of loading 58 to 75 g of oXylol per Nm ³ into the air and an amount of air of a total of 4 Nm ³ per hour and 348 to 350 ° C SBT, the catalyst system G described in example 6. In this case, an average yield in the raw PSA (with respect to 100% purity of o-Xylol) of 114.8% by weight after the loading phase and the phthalate content in the raw PSA were obtained

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48/48 was 0.03% by weight.

Table:

Performance data of catalysts according to the invention

Catalyst system Temperature bathing salt ° C PSA yield gross 0 (after phase load) (% in Weight) Phthalate content 0 in the gross PSA (% by weight) A (comparison) 344-347 113, 4 O, 01 B 346-352 114.0 O, 06 Ç 346-347 115.3 O, 04 D 346-348 113, 9 O, 02 AND 347-348 114, 2 O, 01 F (comparison) 350-354 113, 1 O, 01 G 348-350 114, 8 O, 03

[000160] From the comparison of examples 2 to 5 and comparative example 1 it was found that the use of oxides of silver mixing element as a source of raw material for the manufacture of a catalyst suspension in the first layer placed as near the gas inlet leads to a significant increase in selectivity.

[000161] From the comparison of example 7 with comparative example 6 it was found that the use of silver vanadate in the active mass of the Hot Spot catalyst layer also resulted in an improvement in selectivity, when applied in at least one catalyst layer subsequent to the first catalyst layer

Hot spot.

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Claims (12)

1. CATALYST FOR CATALYTIC OXIDATION OF GAS PHASE OF AROMATIC HYDROCARBONS FORMING ALDEHYDES, CARBOXYLIC ACIDS AND / OR ANhydrides of CARBOXYLIC ACID, characterized by the fact that the active mass contains vanadium oxide, titanium dioxide and at least one element of oxide and at least one element of oxide and at least one element of oxide. mixture of silver with defined elements, according to formula (I): Agx My Nz On (formula I) with Ag = silver, x = 0.01 to 100 M = an element selected from the group Li, Na, K, Rb, Cs, P, Mg, Here, Mr, Ba, You, y = 0 to 1 N = at least one element selected from the group V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ni, Pd, Cu, Au, Zn, Cd, Sn, Pb, B, THERE, Bi, Sb, As, Ti, Zr, Hf, Ce, La, z = 1 O = oxygen, n = a number, which is determined by the valence and frequency of the different oxygen elements in formula I; where in the manufacture of the catalyst, at least the oxide of the silver mixing element and / or at least one precursor compound is used, of at least one element oxide Petition 870170097007, of 12/12/2017, p. 11/18 2/6 of mixing silver as a source of raw material, where the active mass has 0.01 to 15% by weight of an oxide of silver mixing element. 2. Catalyst, according to claim 1, characterized in that the active mass has 0.01 to 10% by weight of an oxide of silver mixing element. 3. Catalyst according to claim 1 or 2, characterized in that the active mass has 0.01 to 5% by weight of an oxide of silver mixing element. 4. Catalyst according to claim 1, 2 or 3, characterized in that at least one oxide of silver mixing element is an oxide of mixing element with at least one other element of the group of vanadium, molybdenum, tungsten, niobium, tantalum, chromium, titanium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, gold, tin, zirconium, antimony, arsenic, cerium, lanthan, bismuth, hafnium, lead, boron, aluminum, ruthenium, rhenium, palladium, rhodium. 5. Catalyst according to one of claims 1 to 4, characterized by the fact that the silver mixing element oxides used as a raw material source in the manufacture of the catalyst and / or oxide mixing element oxide precursor compounds silver mixing element are isolated from the reaction mixture in its manufacture, before its use as a source of material in the manufacture of catalyst or the reaction mixture in question is used directly as a raw material in the manufacture of catalyst. Petition 870170097007, of 12/12/2017, p. 12/18 3/6 6. Catalyst according to one of claims 1 to 5, characterized in that the vanadium mixing element oxide has the formula below (II): M _a N _b V _c O _d (formula II) with M = at least one element selected from the group Nb, OK, Cr , Mo , W, Mn, Re, Fe, Ru, Co, Rh, Ni, Pd, Cu, Au, Zn, Cd, Sn ₁ Pb, B, THERE, Bi, Sb, As, Ti, Zr, Hf, Ce, La The = 0.01 to 100 N = at least one element selected from the group Li, At, K, Rb, Cs, Mg, Ca, Sr, Ba, Tl, P B = O to 1 ^, V = Vanadium c = 1 O = oxygen d = a number, which is determined by the valence and frequency of the different oxygen elements in formula II. 7. Catalyst according to one of claims 1 to 6, characterized in that the catalyst is composed of at least three layers, with the antimony content of at least one layer placed upstream of the Hot Spot catalyst layer in the gas inlet direction is reduced by 20 to 100% by weight with respect to the antimony content of the Hot Spot catalyst layer. Petition 870170097007, of 12/12/2017, p. 13/18 4/6 8. Catalyst according to one of claims 1 to 7, characterized in that the active mass of the catalyst has the following composition after hardening of the catalyst under 400 ⁰ C for a defined period, preferably 4 hours: Vanadium oxide: 1-40% by weight (calculated as V ₂ O ₅ ) titanium dioxide: 50-99% by weight (calculated as TiO ₂ ) AgxMyNzOn: 0.01-15% by weight (calculated as AgxMyNzOn) MaNbVcOd: 0 -10% by weight (calculated as MaNbVcOd) Alkali metal: 0-1.0% by weight (calculated as alkali metal) Antimony oxide: 0-10% by weight (calculated as Sb ₂ O ₃ ) phosphorus: 0-1.5% by weight (calculated as P). 9. Catalyst according to claim 8, characterized in that the active mass of the catalyst, after hardening of the catalyst under 400 ⁰ C for a defined period, preferably 4 hours, presenting the following composition: Vanadium oxide 1-20% by weight (calculated as V2O5); Titanium dioxide: 80-99% by weight (calculated as TiO2); Silver vanadate: 0-5% by weight (calculated as AgVO3); Silver tungstate: 0-5% by weight (calculated as Petition 870170097007, of 12/12/2017, p. 14/18 5/6 Ag ₂ WO4); Silver molybdate: 0-5% by weight (calculated as Ag ₂ MoO4); Bismuth vanadate: 0-3% by weight (calculated as BiVO ₄ ); Cesium: 0-1% by weight (calculated as Cs); Antimony oxide: 0-5% by weight (calculated as ^Sb 2 ^O 3) ^{; and} Phosphorus: 0-1.5% by weight (calculated as P), with at least one oxide of the silver mixing element being a component of the catalyst's active mass. 10. Catalyst according to one of claims 1 to 9, characterized in that at least two different layers are applied in the form of a shell over a preferably ceramic carrier material, at least one layer containing at least titanium dioxide and vanadium oxide and at least one other layer contains at least one silver oxide, and / or vanadium and / or mixed element with or without adicoinal titanium dioxide and vanadium dioxide. 11. Catalyst according to one of claims 1 to 10, characterized in that in at least one layer of catalyst a shell catalyst is used from the gas inlet to the layer with the maximum Hot Spot, whose active mass has a silver mixing element oxide as defined in claim 6 and / or a mixing element oxide Petition 870170097007, of 12/12/2017, p. 15/18 6/6 of the vanadium, as defined in claim 7 and in catalyst as a source of raw material for the manufacture of the catalyst, a silver mixing element oxide and / or a precursor compound of a silver mixing element oxide was employed, and in which catalyst in at least one catalyst layer from the maximum hot spot layer to the gas outlet layer, a shell catalyst is used for the oxidation of aromatic hydrocarbons, which in their active mass contains vanadium pentoxide as essential components and titanium dioxide. 12. Method for the manufacture of aldehydes, carboxylic acids and / or carboxylic acid anhydrides, characterized by being carried out by partial oxidation of aromatic hydrocarbons under high temperature in a catalyst, whose catalytic action mass PE is applied over an inert carrier material , non-porous, where a shell catalyst, whose mass of catalytic action in relation to its total weight, contains 0.01 to 15% by weight of an oxide of silver mixing element with vanadium and / or molybdenum and / or tungsten and / or niobium and / or antimony and at the same time titanium dioxide and a vanadium compound, the mixture element oxide compounds or their precursor compounds being used in the manufacture of the catalyst suspension and / or the powder mixture for the posterior active mass, be used in the presence or absence of at least one shell catalyst, which contains in its active mass essential components of vanadium pentoxide and titanium dioxide in the modification anatase. 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