KR101706790B1 - Catalyst for the catalytic gas phase oxidation of aromatic hydrocarbons to form aldehydes, carboxylic acids and carboxylic acid anhydrides, in particular phthalic acid anhydride, and method for producing said type of catalyst - Google Patents

Abstract

The present invention relates to a catalyst for the formation of aldehydes, carboxylic acids and carboxylic acid anhydrides, in particular phthalic anhydride, from aromatic hydrocarbons by catalytic gas phase oxidation, wherein the active substance of the catalyst is selected from the group consisting of vanadium pentoxide, Titanium, more preferably anatase type titanium dioxide, and at least one silver of a predetermined element, preferably vanadium or molybdenum or tungsten or niobium or antimony, with a mixed element oxide or vanadium and a predetermined element, preferably bismuth or Molybdenum or tungsten or a vanadium mixed element oxide of antimony or niobium, wherein, during the preparation of the catalyst, at least one or more silver or vanadium mixed element oxides, at least one element selected from the group consisting of Use or more precursor compounds, in particular the at least one multi-core precursor compound as a raw material source.

Description

FIELD OF THE INVENTION The present invention relates to a catalyst for forming aldehydes, carboxylic acids and carboxylic acid anhydrides, in particular phthalic anhydride, from aromatic hydrocarbons by catalytic gas phase oxidation, and to a catalyst production method of the above type (Catalysts for the Catalytic Oxidation of Arthritic HYDROCARBONS TO FORM ALDEHYDES, CARBOXYLIC ACIDS AND CARBOXYLIC ACID ANHYDRIDES, IN PARTICULAR PHTHALIC ACID ANHYDRIDE, AND METHOD FOR PRODUCING SAID TYPE OF CATALYST}

BACKGROUND OF THE INVENTION Catalytic gas phase oxidation of aromatic hydrocarbons such as benzene, xylene, naphthalene, toluene or durenne in a fixed bed reactor, preferably a multitubular reactor has long been known and is well known in the literature. In this way, for example, benzoic acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid and pyromellitic anhydride are produced.

For this purpose, a mixture consisting of a gas containing molecular oxygen, for example air, and a hydrocarbon, for example o-xylene or naphthalene, to be oxidized is introduced into a laminate composed of at least one catalyst placed in the reactor Is introduced through a number of reaction tubes present.

The tube filled with the catalyst is surrounded by a heat transfer medium, for example a molten salt, to dissipate the heat generated during the temperature control or exothermic reaction.

Despite this temperature regulation, the catalytic laminate may have a local maximum temperature ("hot spot ") which may, for example, completely oxidize the starting material or form a byproduct An undesirable effect can limit the throughput of the starting material.

In order to prevent such hot spots, catalysts having actually different active and chemical compositions are stacked on top of one another in a layer of a reaction tube, and according to the prior art, the catalyst generally has a low activity in the range of the highest maximum temperature, The activity is increased.

A so-called shell type catalyst, which is generally composed of an inert non-porous carrier material and in which a thin film layer of at least one active mass is applied in a shell form, has been used.

The composition of the catalytic actives plays an important role in the catalytic properties of the associated catalysts.

Many catalysts have been proposed for producing phthalic anhydride by gas phase oxidation of o-xylene or naphthalene with a gas containing molecular oxygen on a stationary phase catalyst from the past.

According to the prior art, catalytic actives of phthalic anhydride-catalyst which are used in practically all industrial fields include small amounts of other components for improving the conversion rate, yield, selectivity and long-term stability of titanium dioxide, vanadium pentoxide, It contains a promoter.

Examples of such additives include cesium, antimony, phosphorus, boron, molybdenum, tungsten, tin, bismuth, silver, niobium, iron, potassium, rubidium, chromium and calcium.

This doping with different materials further enhances the performance and stability of the PSA-catalyst. This suggests that technologies for increasingly complicated catalyst composition and combining different catalysts are being developed over time to solve the problems of the prior art.

Catalysts of so-called "multi-layer structure" are increasingly being used based on the composition of the active substance with respect to activity and selectivity. In this case, a number of different catalysts are sequentially layered on the catalyst laminate to perform different functions in the catalyst bed depending on the layer. The exothermic reaction which takes place at this time allows to safely control the high selectivity and stability of the catalyst at the same time with substantially high throughput to the starting materials.

EP A 21 325 discloses that the activator is composed of 60 to 99% by weight of titanium dioxide, 1 to 40% by weight of vanadium pentoxide, and 2% by weight or less of phosphorus and 1.5% by weight or less of cesium, based on the total amount of TiO ₂ and V ₂ O ₅ Described is a catalyst for the production of a phthalic anhydride containing at least one selected additive, wherein the catalyst activator is applied in two layers on a support. The inner layer contains 0 to 2 wt% phosphorus but not rubidium or cesium and the outer layer contains 0 to 0.2 wt% phosphorus and 0.02 to 1.5 wt% rubidium or cesium. The catalytically active substance of the catalyst contains, in addition to the above-mentioned components, other materials, for example, 10% by weight or less of metal molybdenum, tungsten, niobium, tin, silicon, antimony and hafnium. As the inert carrier material, steatite is used.

EP A 286448 describes a process for the preparation of phthalic anhydrides using two different catalysts with similar contents for titanium dioxide and vanadium pentoxide. One of these catalysts additionally contains 2 to 5% by weight of cesium compounds, in particular cesium sulphate, but does not contain phosphorus, tin-antimony, bismuth, tungsten or molybdenum compounds, Tin-, antimony-, bismuth-, tungsten-, or molybdenum compounds, based on the total weight of the composition.

US 4,864,036 relates to a catalyst for preparing phthalic anhydride through several steps. In the first step, a metal compound of 6-side chain group, preferably a molybdenum or tungsten compound, is applied on the anatase type titanium dioxide and then fired. Thereafter, in the second step, the calcined precursor is added to the vanadium compound and calcined again.

GB 1140264 relates to a catalyst for the oxidation of aromatic and non-aromatic hydrocarbons to carboxylic acids, which catalyst comprises an inert non-porous carrier and a layer of 0.02 to 2 mm thickness and comprising 1 to 15% of V ₂ O ₅ and 85 to 99% Of titanium dioxide, and the vanadium-content in the total catalyst is in the range of 0.05 to 3%. In addition to titanium dioxide and vanadium pentoxide, a catalyst comprising at least one metal oxide selected from the group consisting of silver, iron, cobalt, nickel, molybdenum or tungsten is further added in an amount of 0.1 to 3% by weight.

EP 0447 267 describes a catalyst for the production of phthalic anhydride comprising, as a catalytically active substance, (A) 1 to 20% by weight of V ₂ O ₅ and anatase-type titanium dioxide having a BET surface area of 10 to 60 m ² / g (B) an element selected from the group consisting of K, Cs, Rb and Ti in an amount of 0.05 to 1.2 parts by weight based on 100 parts by weight of the mixture (A) and 0.05 to 2 parts by weight Wealth.

EP 0522 871 B1 is at least one element selected from titanium dioxide and vanadium pentoxide in addition to phosphorus pentoxide and niobium as 0.01 to the group as a niobium oxide of 1% by weight, consisting of 0.05 to potassium, cesium, rubidium, or thallium of 2% by weight, P ₂ As catalysts containing 0.2 to 1.2 wt% phosphorus and 0.55 to 5.5 wt% antimony oxide as O ₅ and 0.05 to 2 wt% silver as Ag ₂ O, a catalyst using a pentavalent antimony compound as an antimony source .

CN 1108996 further relates to a catalyst having two layers based on titanium dioxide / V ₂ O ₅ containing at least one rare earth compound and at least one oxide of antimony, phosphorus, tin and silver, wherein the gas inlet Wherein the layer further contains at least one alkali metal compound.

The silver-vanadium oxide compound with atomic ratio Ag: V <1 is known as silver-bronze. Examples using silver-vanadium bronze as oxidation catalysts are generally known in the literature.

The multi-element metal oxides described in DE 198 51 786 A1 are represented by the general formula Ag _{a - b} M _b V ₂ O _x * c H ₂ O wherein a has a value of from 0.3 to 1.9, M is Li, Wherein the metal is selected from the group consisting of Na, K, Rb, Cs, Tl, Mg, Ca, Sr, Ba, Cu, Zn, Cd, Pb, Cr, Au, Al, Fe, Co, Ni and / b has a value of 0 to 0.5, and ab is 0.1 or more. The use of said multinary element metal oxide as a precursor catalyst for the gas phase oxidation reaction of aromatic hydrocarbons and as a precursor compound for preparing catalysts is described.

Finally, WO 2005/092496 A1 describes a catalyst for the production of aldehydes, carboxylic acids and / or carboxylic acid anhydrides, which comprises phases A and phase B in the form of a three-dimensionally expanded compartment region, The catalyst A is based on titanium and vanadium pentoxide, the phase A is silver-vanadium-brass and the phase B is a mixed element phase. The molar ratio of Ag: V in the phase A is in the range of 0.15 to 0.95.

These catalysts known in the prior art having various active compound compositions are unsatisfactory in selectivity, yield or activity, are short in life span, or require significant cost in industrial preparation.

There has thus been a continuing need for catalysts with improved selectivity and yields, high raw material throughput, long lifetimes and acceptable cost-benefit ratios.

The object of the present invention is to provide an improved catalyst for forming an aldehyde, a carboxylic acid and a carboxylic acid anhydride, especially a phthalic anhydride, from an aromatic hydrocarbon by a gas phase oxidation reaction, wherein the catalyst has high raw material throughput and improved selectivity It has a long life span.

The above problem is solved by the features of claim 1. Preferred embodiments are described in the dependent claims, the contents of which are incorporated herein.

Claim 1 describes a catalyst for the formation of aldehydes, carboxylic acids and carboxylic acid anhydrides, especially phthalic anhydride, from aromatic hydrocarbons by catalytic gas phase oxidation, wherein the active substance of the catalyst is vanadium oxide, At least one silver mixed element oxide of a predetermined element, preferably vanadium or molybdenum or tungsten or niobium or antimony, or a mixed element oxide of silver, Vanadium and a predetermined element, preferably bismuth or vanadium mixed oxide of molybdenum or tungsten or antimony or niobium. At least one silver or vanadium mixed element oxide, at least one precursor compound, in particular at least one polynuclear precursor compound is used as a raw material supply during the preparation of the catalyst, especially during the preparation of the powder mixture necessary for coating the catalyst suspension or carrier .

Surprisingly, a mixed element oxide of a mixed element oxide, preferably a mixed oxide of vanadium, molybdenum, tungsten, niobium or antimony with silver, preferably a mixed oxide of bismuth, molybdenum, tungsten, niobium or antimony, The selectivity is clearly increased when its precursor compound is used as a raw material supply source in the preparation of the powder mixture used in the preparation of the catalyst suspension or in the application process or as a constituent of the active substance of the catalyst in addition to the components titanium dioxide and vanadium oxide lost.

Although the cause of this is not clearly explained, the interaction between the silver and other catalytically active components such as titanium dioxide / vanadium oxide monolayer, for example, has a substantial effect, and as a result the inherent promoting effect of silver (carbon monoxide The effect of inhibiting complete oxidation of amorphous silicon) is expected to be effective.

A number of examples using silver as a constituent of an active material have been described in the prior art. According to these, besides silver oxide, a suitable silver source such as silver nitrate, silver sulfate, silver halide, silver sulfide, silver phosphate, organic acid silver salt, silver hydroxide, antimony silver salt and silver complex is used as a raw material supply source of silver for preparing a catalyst suspension. Most of these feedstocks are converted into mononuclear silver oxide by heating the catalyst in the reactor and are present in the active material as silver oxide, while silver phosphate and silver halide do not convert to an activator and do not convert to silver oxide upon heat treatment.

A substantial point of the present invention is a catalyst comprising titanium oxide and vanadium oxide as the activator and a mixed element oxide of silver and vanadium or any other element or a mixed element oxide of vanadium and any other element as an additional coating material , At least one or more mixed element oxides of silver or vanadium, or a corresponding precursor compound is added during the preparation of the powder mixture used for the preparation of the catalyst suspension or coating of the carrier.

The present invention also relates to a method for producing the catalyst of the present invention as described above, which comprises preparing a catalyst suspension or a mixture of different components, wherein the catalyst suspension or a mixture of different components comprises at least anatase titanium dioxide A mixed oxide of a vanadium compound and at least one silver or vanadium and a predetermined element or a corresponding precursor compound as a raw material supply source.

It is preferable that all the components are mixed with each other in an aqueous medium and then applied onto a ceramic carrier through a spraying method (preferably a vortex- or drum method). Silver or vanadium oxide or a mixed element oxide-precursor compound thereof is added to the catalyst suspension comprising titanium dioxide, vanadium oxide and other accelerators as main components and is not present as a generally separated phase in space, And vanadium oxide. Whereby all constituents of the catalyst suspension form a single phase which in addition to the titanium dioxide and vanadium oxide further contains the corresponding mixed element oxides and optionally other components.

It is also possible to have a catalyst system in which different layers having different chemical compositions are sequentially applied on an inert carrier and at least one layer contains silver or at least one mixed element oxide of vanadium and a predetermined element. In this case, each of the coatings-layers of the catalyst according to the invention may consist of a composition according to the invention and a composition not according to the invention.

The mixed element oxides may be used alone or in combination with other compounds in one or more coating layer (s), and the coating layer may contain no titanium dioxide or vanadium oxide as the active material.

According to the present invention, a catalyst and a catalyst precursor for carrying out a gas phase partial oxidation reaction of an aromatic hydrocarbon using a molecular oxygen-containing gas can be provided, wherein the catalyst or the catalyst precursor includes an inert nonporous carrier material and one or more shells At least one of the layers contains one or more of the above-described mixed element oxides or precursor compounds in an amount of 0 to 15% by weight, based on the total weight of the layer.

In addition, the present invention claims a specific manufacturing process for producing a carboxylic acid or a carboxylic acid anhydride through a gas phase partial oxidation reaction of an aromatic hydrocarbon at a high temperature by a gas containing molecular oxygen on a catalyst, And the catalytic activity of the shell-type catalyst is 0 to 15% by weight based on the total weight of the shell-type catalyst, a mixed element oxide of silver and vanadium or a mixed element oxide of silver and any other element, and 0 To 10 wt% of a mixed element oxide of vanadium and bismuth or a mixed element oxide of vanadium and a predetermined other element, and at the same time an anatase type titanium dioxide and a vanadium compound (preferably V ₂ O ₅ ) The oxide-compound (s) or precursor compound (s) thereof is formed by the heat treatment after the coating of the carrier, It characterized in that it is used for producing a sheet or a suspension powder mixture.

In this case, when the aromatic hydrocarbon is oxidized to a carboxylic acid or a carboxylic anhydride, the active substance contains vanadium oxide, in particular vanadium pentoxide and titanium dioxide, especially anatase-type titanium dioxide as a substantial constituent, At least one shell-type catalyst which does not contain the precursor compound of the present invention may or may not be present and may be in the form of a laminate which is combined with one or more of the catalysts of the present invention, Lt; / RTI &gt;

For this purpose, it is preferable to introduce the airflow into the catalyst bed of at least two or more catalyst beds, wherein the catalyst bed located near the gas inlet contains the catalyst according to the present invention, The active material contains vanadium oxide and anatase-type titanium dioxide, but a mixture of elemental oxides of vanadium, molybdenum, tungsten, niobium and antimony with silver or vanadium, for example, bismuth, molybdenum, tungsten, niobium, And contains at least one catalyst that does not contain any mixed element oxide with the same element at all.

A catalyst laminate composed of at least two layers containing the catalyst according to the present invention may be used. In this case, the catalyst according to the present invention can be distinguished by the form and content of the corresponding mixed element oxide in the active material.

Preferably all catalyst layers used in the catalyst bed, including at least one catalyst layer, particularly preferably the catalyst of the present invention, comprise 1 to 40 wt% vanadium oxide (expressed as V ₂ O ₅ ), 50 to 99 wt% (Expressed as TiO ₂ ), not more than 1 wt% of an alkali metal compound (preferably a cesium compound, as an alkali metal), not more than 1.5 wt% of a phosphorus compound (shown as P) and not more than 10 wt% of an antimony compound (Expressed as Sb ₂ O ₃ ).

According to a particularly preferred embodiment, the catalyst according to the invention is preferably selected from the group consisting of silver and vanadium, niobium, tantalum, titanium, zirconium, chromium, molybdenum, tungsten, cerium, lanthanum, aluminum, boron, manganese, iron, cobalt, 0 to 15% by weight of at least one mixed oxide of at least one element selected from the group consisting of copper, zinc, gold, cadmium, tin, lead, bismuth, antimony, arsenic, hafnium, rhenium, ruthenium, rhodium, And at least one of vanadium, bismuth, antimony, niobium, tantalum, titanium, zirconium, chromium, molybdenum, tungsten, cerium, lanthanum, aluminum, boron, manganese, iron, cobalt, nickel, copper, zinc, gold, cadmium, At least one element selected from the group consisting of hafnium, rhenium, ruthenium, rhodium and palladium. The.

The content of silver in the active material of the catalyst and a predetermined element, for example, a mixed oxide of vanadium or tungsten or molybdenum or niobium or antimony, in the preferred embodiment is in the range of 0 to 15% by weight, 0 to 10% by weight, particularly preferably 0 to 5% by weight. The content of the vanadium in the active material of the catalyst and the mixed element oxide of the predetermined element (for example, the mixed oxide of silver and vanadium, except for silver) mentioned above, particularly, for example, tungsten or molybdenum or niobium or antimony, From 0 to 10% by weight in the embodiment, and from 0 to 5% by weight in the particularly preferred embodiment.

In a preferred embodiment, the catalyst of the present invention is used in the first catalyst bed, which is the catalyst bed closest to the gas inlet and having the highest hot spot. At least one or more other catalyst layers, which are generally more active than the first catalyst layer and generally capable of providing catalysts according to the prior art, are connected to the gas exhaust portion. Wherein the catalyst according to the invention contains at least one or more mixed element oxides of silver, preferably silver vanadium oxide, and preferably a mixed element oxide of vanadium, preferably bismuth vanadium.

It is preferable to use a multilayer catalyst system having at least one or more hot spot catalyst layers in the layer positioned forward in the direction of the gas inlet. In this multi-layer catalyst system, at least one of the catalyst layers from the gas inlet to the layer having the highest hot spot, And a catalyst of the prior art is used for the rear layer or, in the case of the catalyst according to the present invention, a reduced content of the mixed element oxide required for the activator is used.

In another particularly preferred embodiment, the at least one catalyst layer present in front of the layer with the highest hot spot contains a mixed element oxide of silver, preferably a mixed element oxide of silver and molybdenum or tungsten, particularly preferably silver and vanadium , While the layer with the highest hot spot and the layer lying down along the airflow contain no mixed element oxides of silver at all. It is preferable that the layer having the highest hot spot contains a mixed element oxide of vanadium and bismuth. The catalyst layer located behind the hot-spot catalyst layer in the direction of the gas outlet preferably corresponds to the prior art and generally does not contain the catalyst according to the present invention.

In a particularly preferred embodiment of the catalyst, the compound AgVO ₃ , Ag ₂ MoO ₄ , Ag ₂ WO ₄ or BiVO ₄ is used in the preparation of the catalyst suspension or contained in the active substance of the catalyst.

It is important that the content of the mixed element oxide serving as "promoter" is selected to be small or not so large. When the content of oxide of the mixed oxide of silver is small, the effect of increasing the selectivity is not sufficiently effected. On the other hand, when the content of oxide of mixed element of silver is high, high activity is observed, which increases the complete oxidation reaction with CO and CO ₂ .

The catalyst according to the invention is more preferably used in all layers, in particular from the catalyst bed located near the gas inlet to the layer with the highest hot spot, since otherwise most of the feed has already been converted, Or more.

A high content of bismuth mixed oxide may negatively affect the selectivity of the catalyst, and may also result in formation of more by-products, which may deteriorate the color stability of the desired product. On the other hand, if the oxide content of the mixed oxide of bismuth is small, the effect of increasing the selectivity is not significantly exhibited.

When a laminate including the catalyst according to the present invention is used in at least one of the catalyst layers through at least two, particularly preferably a plurality of, combinations of catalyst layers, the multilayer catalyst system and the catalyst not according to the present invention are used alone A significantly higher yield can be obtained as a whole.

According to the prior art, in many cases, the catalytic activity gradually increases from the first catalyst layer used in the gas inlet to the last catalyst layer located closest to the gas outlet. Activity modulation can be accomplished through a variety of methods known to those skilled in the art. For example, by gradually reducing the content of alkali metal in the active material in the layer from the gas inlet to the gas outlet, increasing the average BET-surface area of the titanium oxide used, or increasing the activity The catalyst activity can be increased by increasing the sieve component. It is also possible to combine different methods for activity regulation.

The catalyst according to the present invention comprises at least one anatase type titanium dioxide, at least one vanadium compound (preferably V ₂ O ₅ ), at least one mixed oxide of at least one silver or vanadium, and optionally an antimony compound, It is advantageous to include a compound of an alkali element or a phosphorus compound.

The total content of titanium dioxide in the active material of the catalyst according to the present invention is 50 to 99% by weight, particularly preferably 80 to 99% by weight.

In this case, one kind of anatase type titanium dioxide having a predetermined physical property or a mixture of titanium dioxide having a different physical property can be used for the production of a catalyst suspension or an activator of a catalyst.

The average BET surface area of the titanium dioxide used in the catalyst according to the invention is advantageously 10-60 m ² / g, in particular 12-30 m ² / g for one or more titanium dioxide species, whereas for BET- The surface area is in the range of 3 to 300 m ² / g.

The average BET surface area of the titanium dioxide used is calculated from the content of the species used and the BET surface area. At least one kind of titanium dioxide having an average particle size in the range of 0.3 to 0.8 mu m is used.

The content of vanadium oxide in the active material (expressed as V ₂ O ₅ ) is preferably in the range of 1 to 40% by weight, and in a particularly preferred embodiment is in the range of 1 to 20% by weight.

It is advantageous to use vanadium pentoxide or vanadium oxalate as the feedstock for the preparation of the catalyst according to the invention. In general, other vanadium compounds such as, for example, ammonium metavanadate, of which polyanadium acid or mixtures of different sources are suitable.

In general, the precursor compound or source of vanadium is converted into vanadium pentoxide upon heat treatment of the catalyst in the presence of molecular oxygen in the reactor or heating of the catalyst, so that vanadium in the active is present in a substantially tetravalent oxidation step.

Depending on the respective layers of the catalyst according to the invention in the catalyst bed, the catalytically active substance may comprise one or more elements selected from the group consisting of titanium dioxide, vanadium oxide, one or more mixed element oxides of silver or vanadium and additionally alkali metals .

Are generally added as salts of catalyst suspensions (e.g., sulphates, carbonates, nitrates, phosphates) and are converted into the corresponding oxides upon catalyst heating or remain unchanged within the active (after heat treatment of the catalyst).

Alkali metal compounds are used to improve catalytic activity along with activity control.

In a preferred embodiment, the alkali metal content in the active is in the range of 0 to 1.0% by weight and particularly preferably in the range of 0 to 0.6% by weight. It is preferable to use a soluble cesium compound such as cesium sulfate in order to prepare a catalyst suspension.

The catalyst according to the present invention preferably contains an antimony compound as one component of the active material in order to improve the thermal stability of the active material of the hot spot catalyst layer. The antimony content in the active material is preferably in the range of 0 to 10% by weight (expressed as Sb ₂ O ₃ ) and particularly 0 to 5% by weight, depending on the layer of the catalyst in question and the heat treatment of the catalyst in each layer .

As a starting material for the powder mixture of the catalyst according to the invention which is necessary for preparing the catalyst suspension or coating the carrier, different antimony compounds such as, for example, antimony salts or antimony oxides can be used in different oxidation steps.

In a preferred embodiment of the catalyst according to the invention, antimony-III-oxide is used in the preparation of the catalyst suspension.

In some cases, the catalyst according to the present invention may contain a phosphorus compound in the catalytically active form or may be added as a feedstock source in the preparation of a powder mixture used for catalyst suspension preparation or carrier coating. In a particularly preferred embodiment of the catalyst according to the invention, the phosphorus content of the active is in the range from 0 to 1.5% by weight (expressed as P).

It is particularly advantageous to increase the phosphorus content from the gas inlet to the gas outlet in a catalyst system comprising a plurality of layers with one or more catalysts according to the invention, or with one or more catalysts according to the invention in the laminate.

The activator of the catalyst according to the present invention may contain small amounts of a number of other compounds which can reduce or increase activity as an accelerator or affect the selectivity of the catalyst.

The prior art discloses the use of multilayer catalysts as a means of reducing or preventing activity modulation or so-called " hot spots ", in which the layers in the catalyst laminate, particularly a plurality of layers, The least active catalyst exists at the position closest to the inlet and the catalyst activity increases toward the gas outlet.

The catalysts in each layer have different chemical compositions and have different activity and selectivity.

In a multi-layer catalyst system, it is preferred that at least one of the layers contains a catalyst according to the invention containing at least one of the corresponding mixed element oxides.

The first layer located closest to the gas inlet and having the highest hot spot contains the catalyst of the present invention. It is particularly preferred that all layers in the catalyst bed, that is, all layers from the gas inlet to the layer with the highest hot spot, contain the catalyst according to the invention. For example, the content and morphology of mixed element oxides of silver in different layers may vary. It is advisable to adjust the other composition of the activator to suit each layer in the catalyst bed.

In a preferred embodiment, the layer with the highest local maximum temperature comprises a mixed element oxide of silver, or alternatively a mixed element oxide of bismuth and vanadium.

In particular, the use of a combination of elemental oxides of AgVO ₃ and BiVO _{4 in} the layer having the highest temperature has the effect of increasing the activity of the catalyst according to the present invention.

Surprisingly, it has been found that at least one of the active components of the catalyst layer above the air stream upstream of the layer with the highest hot spot advantageously has a lower antimony content in the active component than the layer with the highest hot spot .

In another preferred embodiment of a catalyst having a plurality of layers in one or more stacks, at least one catalyst layer located in front of the hot spot-catalyst layer is formed of silver and a predetermined element, particularly advantageously vanadium or molybdenum or tungsten And at least one or more of the mixed element oxides.

In a particularly preferred embodiment of the catalyst according to the invention, at least one of all the layers from the gas inlet to the layer with the highest hot spot has a mixed oxide of silver and, in particular, silver and vanadium or molybdenum or tungsten While the layer with the highest hot spot contains mixed element oxides of vanadium, in particular mixed element oxides of vanadium and bismuth.

In another particularly preferred embodiment, all layers from the gas inlet to the layer with the highest hot spot contain a mixed element oxide of silver and the layer with the highest hot spot further contains a mixed element oxide of vanadium and bismuth.

It is particularly advantageous to use a polynuclear mixed oxide or its precursor compound as a source in the preparation of the catalyst suspension or in the preparation of the powder mixture used for the carrier coating.

A mixed element oxide of silver having a smaller or larger atomic ratio to silver than that of AgVO ₃ may be used for the preparation of the catalyst suspension or the production of the activator. The content of silver in the active material of the catalyst prepared by controlling the amount of the mixed element oxide or its precursor compound in the catalyst suspension or the powder mixture used for the coating should be appropriately controlled depending on the atomic ratio of the elements in the mixed element oxide.

If the mixed element oxide phase or a precursor compound thereof is already formed, the catalyst suspension or the carrier may be added in advance to the powder mixture used for coating. One or more corresponding precursor compounds may also be added to the catalyst suspension or powder mixture, which are then converted to the appropriate mixed oxide oxides upon heat treatment of the catalyst.

As already described, the mixed oxide of the elemental oxide or its precursor compound with silver and other elements present in the molar ratio of the purified water as the source of the raw material can be used in the production of the catalyst suspension or in the active substance of the catalyst according to the present invention As well as binary or multicomponent mixed element oxides with silver having a smaller or larger atomic size than that of silver. Depending on the composition of the mixed element oxide or its silver component, the content of the corresponding mixed element oxide in the catalyst suspension or the active material is increased or decreased.

The silver binary core or polynuclear mixed element oxide is represented by the general formula I according to claim 11:

Ag _x M _y N _z O _n (general formula I)

In the mixed element oxides of the general formula I, x preferably has a value of 0 to 5, and the value of the variable y is preferably 0 to 0.3.

Particularly preferred are mixed element oxides of the general formula:

Ag _x N _z O _n

In the above formula

Ag =

x = 0.1 to 1,

N is an element selected from the group consisting of vanadium, molybdenum, tungsten, niobium, and antimony,

z = 1,

n = a number determined by the bond and frequency of oxygen and other elements in the general formula I.

In principle, in the preparation of the catalyst suspension, the catalyst according to the invention, using one or more precursor compounds of the corresponding mixed element oxides or starting compounds thereof and comprising the corresponding mixed element oxides, is first heated and fired in the reactor, Can be formed during heating, which can be clearly seen from the present invention.

In a preferred embodiment of the catalyst of the present invention, mixed element oxides AgVO ₃ , Ag ₂ MoO ₄ , Ag ₂ WO ₄ or mixed element oxides of these elements with different atomic ratios are used to improve the performance of the catalyst.

For the catalyst suspension, "mononuclear" refers to a catalyst or oxide (AgO or Ag ₂ O) that does not contain silver in the active body, instead of a compound, and preferably a mixed oxide of vanadium, tungsten and molybdenum, Or as a salt, or as a salt of a salt (nitrate, phosphate, sulphate, hydrochloride, ammonium salt, organic acid) or as a hydroxide or as an amine-complex of a catalyst suspension. It is expected that silver in the form of mixed element oxides or mixed element compounds will be more effective in catalytic processes than in salt form or mononuclear oxides.

As a non-limiting example, although the compound AgVO ₃ as a component of the catalyst according to the present invention can be used as an additive in the preparation of a catalyst suspension or an active material, the active material includes at least anatase-type titanium dioxide and a vanadium compound. Preferably, the catalyst according to the invention also comprises at least one compound corresponding to at least a first major group. Depending on the layer of the catalyst according to the invention in the catalyst bed, the catalyst according to the invention contains an antimony compound, in particular Sb ₂ O ₃ and optionally a phosphorus compound, in the active.

Surprisingly, it has been found that a multi-layered catalyst prepared using at least one or more of the precursor compounds of silver and vanadium or mixed element oxides of tungsten or molybdenum is very advantageous in terms of increasing the selectivity, Layer to the layer having the highest point of the highest temperature.

In a particularly preferred embodiment, one or more or all of the catalyst layers from all of the catalyst layers from the gas inlet to the layer with the highest point of hotness, or all of the catalyst layers, contain 0-15 wt% of a mixed element oxide of silver and vanadium or tungsten or molybdenum in the active, By weight, in particular from 0 to 10,0% by weight and most preferably from 0 to 5% by weight.

In a particularly preferred embodiment of the catalyst according to the invention, the compound wherein the molar ratio of Ag: V in the silver-vanadium-mixed element oxide is 1: 1 is the mixed element oxide AgVO ₃ . In this case, the so-called silver-vanadium-bronze is not considered by definition because the atomic ratio of Ag: V is less than 1: 1.

In addition, vanadium and a raw material supply source may be formed of a metal such as bismuth, molybdenum, tungsten, antimony, bis, lead, tin, zinc, copper, nickel, cobalt, iron, manganese, chromium, niobium, zirconium, titanium, gold, rhenium, lanthanum, It has been found that the selectivity is improved when the mixed element oxide of rhenium is used as a catalyst component or as a constituent component of an activator.

In particular, bismuth vanadium oxide is used as a source of raw materials for the preparation of the catalyst suspension or as a constituent of the activator for the improvement of selectivity. In this case, it is preferable that the catalyst BiVO ₄ according to the present invention as a constituent of the active material is contained in one or more layers particularly from the gas inlet to the layer having the highest temperature.

The catalyst according to the present invention comprises, in addition to titanium dioxide and vanadium oxide, one or more mixed element oxides of silver and the above-mentioned elements, and one or more mixed element oxides of vanadium and the above-mentioned elements. In a particularly preferred embodiment, vanadium acid and bismuth vanadate are used or co-existed in the catalyst active to produce a catalyst suspension of the catalyst according to the invention.

Depending on the layer of the catalyst according to the invention in the catalyst laminate, the catalyst according to the invention comprises at least one alkali metal compound, preferably a cesium compound, an antimony compound, preferably an antimony-III-oxide and, .

The mixed oxide of vanadium and other elements present in the atomic ratio of the purified water in the production of the catalyst suspension can be used as the raw material supply source or in the active material of the catalyst according to the present invention, A binary or multinuclear mixed element oxide of vanadium with a smaller or larger atomic size than vanadium can be used. Depending on the general formula of the mixed element oxide or vanadium component thereof, the content of the corresponding mixed element oxide in the catalyst suspension or the active material is increased or decreased.

The binary or multicomponent mixed element oxide with vanadium is represented by the following general formula according to claim 12:

M _a N _b V _c O _d (formula II)

As the catalyst according to the present invention, there can be exemplified a so-called "shell type catalyst ", in which the catalyst activator is selected from porcelain, magnesium oxide, tin oxide, silicon carbide , Cerium silicate, magnesium silicate (stearate), zirconium silicate, aluminum oxide, quartz, or a mixture of these carrier materials. In the prior art, particularly stearate or silicon carbide was used as the carrier material.

Such a shell-type catalyst typically comprises a solution or suspension (referred to herein as a "catalyst suspension") containing an aqueous or organic solvent of an active constituent or a precursor compound thereof, 2106796) until the desired active ingredient is achieved, based on the total weight of the catalyst. The inert nonporous carrier material may be coated with the active ingredient or a precursor compound thereof as a suspension or powder mixture while heating in a heated dragee production drum.

The atomization of the catalyst suspension when spraying the catalyst suspension containing the active component or the precursor compound contained therein or when coating the inert carrier material in the drum or eddy current drum for producing sugar alcohols and / Partial erosion of the carrier takes place and partly high losses appear, so in the prior art it has been found that in the prior art, an organic binder, preferably a copolymer, preferably vinyl acetate / vinyl laurate, vinyl acetate / In the form of an aqueous dispersion of styrene / acrylate, vinyl acetate / maleate and vinyl acetate / ethylene, wherein the amount of the conventional binder is 10-20% by weight relative to the solids content of the catalyst suspension used. The coating temperature during the addition of the binder material is preferably in the range of 50-450 ° C. The binder material is added as soon as the reactor is heated above the operating temperature as soon as the catalyst is placed in the reactor or when the effect of the catalyst is initiated at the latest and is completely separated from the catalyst.

In this case, the catalytically active component remaining on the inert carrier material as the thin film shell is considered as an active substance. The components of this activator may be derived in part from the components used in the catalyst suspension, or from the feedstock source or precursor compound, which is chemically partially converted through the heat treatment of the catalyst and converted into the corresponding metal oxide in particular.

Surprisingly, the performance of the catalyst depends entirely on the composition of the catalyst and on the amount of active (after the temperature of the heated or formed catalytically active compound) and on the composition of the powder mixture used for the coating of the catalyst suspension or carrier Have a great influence on the selectivity, activity and service life of the catalyst.

The present invention also relates to a process for preparing an aldehyde, carboxylic acid or carboxylic acid anhydride by bringing a gas stream containing an aromatic hydrocarbon and containing a molecular oxygen-containing gas into contact with a predetermined catalyst in a heated state.

Mixed element oxides used as feedstock for the catalyst suspension can be prepared in a variety of ways and incorporated directly into the catalyst suspension in the form of separate compounds or reaction mixtures. Optionally, a corresponding precursor compound of the mixed metal oxide of the catalyst suspension may be added. In this case, the polynuclear mixed compound compound or the mixed metal oxide compound is generally a mixed element oxide present in an active material and suitably heat-treated, and may contain another crystal structure and contain crystal water thereon.

In most cases for the preparation of the mixed element oxides and / or their precursor compounds used in the catalyst according to the invention, it may be appropriate to convert the solution of the metal compound to a suspension of the metal oxide in an aqueous or non- have. For example, the silver-vanadium-oxide used for the catalyst according to the present invention can preferably be prepared by converting silver nitrate and vanadium pentoxide into the corresponding desired atomic ratio in a hot aqueous solution. At this time, the reaction mixture containing the mixed metal compound contained therein may be directly added to the catalyst suspension, or the mixed metal compound may be separated before the heat treatment as occasion demands.

In addition to water, a polar organic solvent such as polyol, polyether or amine may be used as the solvent. Metal oxides or many metal oxides (e.g., vanadium pentoxide and molybdenum trioxide) can be converted with silver compounds and optionally other compounds (such as phosphorus compounds), usually at ambient temperature or with heating. Preferably, the reaction is continued for 20 minutes to 5 days, depending on the starting materials and reaction conditions used at 50-100 &lt; 0 &gt; C.

The thus formed mixed metal compound is separated from the reaction mixture and optionally stored for other uses or added directly as a suspension of a catalyst suspension containing at least titanium dioxide and a vanadium compound. The mixed metal compound obtained through the above reaction may be reacted while heating before adding the catalyst suspension to convert the crystal structure and remove the crystal water.

When the mixed metal compound is separated in advance, the suspension is filtered and the obtained solid is dried, and this drying can be carried out in various ways. It is advisable to dry the mixed metal-suspension through spray drying or lyophilization.

Another reaction in the solution can also be obtained by co-melting the mixed metal compound, which is converted into a variety of finely mixed metal oxide powders, for example, at a high temperature of 400 to 800 DEG C in a solid reaction.

The components of the catalyst suspension are generally used in the form of a compound such as a salt which is converted to an oxide by heating in the presence of an oxide or, for example, oxygen. Metal salts, such as phosphates or halides, may also be added to the catalyst suspension, which remain unchanged as catalyst activators after heat treatment.

Catalysts according to the invention can generally be prepared from precursors of the final catalyst, which catalyst precursors can be stored in that state. In this case, it is preferable that the raw material used for the catalyst suspension is applied onto the inert ceramic carrier by spraying and fixed using an organic binder material.

The active catalyst is generally produced when the catalyst precursor is heat treated or the catalyst is heated in the reactor. In this case, commonly used metal compounds are converted to the corresponding metal oxides. For example, when vanadium oxalate is added, it is converted to V ₂ O ₅ . In some cases, the catalyst contained in the catalyst suspension is converted to its oxidized form when heated. Ammonium dihydrogen phosphate is converted to P ₂ O ₅ and is present in the active substance as it is. In this case, an aqueous mixed metal oxide is generally prepared and used as a raw material supply source in the production of the catalyst suspension, since crystal water is generally lost during the heat treatment of the catalyst and the crystal structure thereof is changed in some cases.

The conversion reaction of the feed source used in the catalyst suspension takes place preferably at a temperature of from 200 to 500 ° C, particularly preferably in a range of from 300 to 500 ° C.

The form of the inert carrier material does not depend on the performance of the catalyst according to the invention, but it has been found that spherical or annular shaped bodies are advantageous in the prior art.

The layer thickness of the active material or the total layer thickness of the shell containing the active is generally between 20 and 400 탆 and depends on the layer of the catalyst according to the invention in the catalyst bed.

It has surprisingly been found that it is generally unnecessary to spatially separate the different components of the catalyst suspension from the mixed metal oxides used to obtain the improved catalyst. All components used in the catalyst suspension are generally mixed with or mixed with the mixed metal oxide, and at the same time the mixed suspension is applied to an inert carrier. Catalyst suspensions of different compositions may be sequentially applied to the inert ceramic carrier, but the improved catalyst according to the present invention can be obtained because at least one of the layers contains the catalyst according to the present invention.

In addition, catalyst suspensions which are not in accordance with the invention, which contain titanium dioxide, vanadium compounds and preferably alkali metal compounds, are first separated and, optionally after heat treatment, the resulting powders are generally preceded by at least titanium dioxide, vanadium compounds and Improved catalysts are also possible which are prepared by mixing again (preferably in water) with powders obtained from a catalyst suspension composed of at least a mixed metal oxide or a precursor thereof. These new catalyst suspensions may be applied alone as a layer on an inert ceramic carrier or in combination with other coating-layers according to the invention or other coating-layers not according to the invention.

The catalysts according to the invention are generally used for the production of aldehydes, carboxylic acids or carboxylic acid anhydrides from aromatic hydrocarbons by partial gas phase oxidation. The catalyst is particularly suitable for the vapor phase oxidation of o-xylene or naphthalene with phthalic anhydride as a molecular oxygen-containing gas.

As already mentioned, the catalyst according to the invention can be used for this purpose, either alone or in combination with other various active catalysts, for example catalysts of the prior art (vanadium pentoxide / anatase- ) Can be used in combination.

Catalysts according to the present invention and catalysts according to the present invention which are not according to the invention are generally used in separate catalyst laminates disposed in at least one catalyst bed. It is very good to use the catalyst according to the present invention in the layer closest to the gas inlet among the layers from the layer closest to the gas inlet to the layer having the highest point.

The use of the catalyst according to the present invention in the catalyst layer positioned next to the layer with the highest hot spot and in the layer located close to the gas outlet also has a positive effect, but with respect to selectivity, Lt; RTI ID = 0.0 &gt; catalyst. &Lt; / RTI &gt; The catalyst according to the invention and its precursor catalyst are packed in layers in the reaction tube of the reactor. In this case, the different layers can be constituted by the catalyst according to the present invention and the catalyst according to the present invention.

A laminate of a mixture of at least one catalyst according to the invention and at least one catalyst according to the invention is used as a layer and this layer is used alone or in combination with a catalyst according to the invention and a catalyst according to the invention It may be possible to use it in combination with other catalyst layers.

The reaction tube is generally temperature controlled from the outside by a molten salt surrounding the tube.

Upon heating the reactor with the catalyst-filled reaction tube and subsequent heat treatment of the catalyst resulting from the catalyst precursor with inherent catalytic activity, the organic binder is calcined therein and the feedstocks used in the catalyst suspension are generally oxidized to the corresponding oxides . The chemical composition and crystal structure may vary depending on the type of the mixed metal compound.

In the laminate composed of at least one catalyst according to the present invention thus heat treated, the reactive gas is introduced at a temperature of 250-550 DEG C, especially 330-500 DEG C, and usually at a pressure of 0.1-2.5 bar, preferably 0.3-1.5 bar The space velocity is typically 1000 to 5000 h (-1).

The reactive gas introduced into the catalyst is typically mixed with a molecular oxygen-containing gas, preferably air, through which the oxygen may contain an appropriate reaction control or diluent such as steam, nitrogen or carbon dioxide and is mixed with an aromatic hydrocarbon to be oxidized, The molecular oxygen-containing gas generally comprises 1 to 100% by volume and particularly preferably 10 to 30% by volume of oxygen, 0 to 30% by volume of water vapor, preferably 0 to 20% by volume of water vapor and 0 to 50% Preferably 0 to 1% by weight of carbon dioxide, and the balance of nitrogen. To form the reaction gas, the molecular oxygen-containing gas is generally mixed with 20 to 200 g per Nm ³ of aromatic hydrocarbons to be oxidized, particularly preferably 60 to 120 g per Nm ³ .

In a preferred embodiment of the process for partial oxidation of aromatic hydrocarbons with aldehydes, carboxylic acids or carboxylic acid anhydrides, the aromatic hydrocarbons are first preferentially added to the present invention in order to oxidize o-xylene or naphthalene to phthalic anhydride In the catalytic laminate according to the invention, into a reaction mixture consisting of the starting material, an intermediate product and an end product, and the mixture is optionally converted by a catalyst according to the invention or a catalyst according to the prior art, .

This reaction can be carried out by one or more reactors, each reactor comprising at least one catalyst laminate which can be adjusted to different reaction temperatures and which has at least one catalyst layer. It is sufficient to carry out the process according to the invention if at least one reactor comprises a layer with a catalyst according to the invention.

To prepare the phthalic anhydride from o-xylene, the partially converted reactant gas after passing through one or more catalyst beds with the catalyst according to the present invention is reacted with a substantial amount of unconverted o-xylene in addition to the desired product phthalic anhydride For example, intermediate products such as o-tolyl aldehyde, o-tolyl acid and phthalide.

The product mixture is then generally separated from the catalyst according to the present invention in terms of its chemical composition and activity, reaching on at least one catalyst layer without further separation and the raw material is completely converted to the phthalic anhydride or the non- .

It is also possible to separate the unconverted o-xylene after passing through a catalyst laminate with the catalyst according to the invention before the reaction gas is introduced into at least one or more other catalyst laminates. Such a modification is technically feasible though the cost is relatively large.

It is therefore desirable to pass the reaction mixture to more catalyst beds without separating the starting material or the intermediate product, wherein the layer (s) located near the gas inlet in at least one of the catalyst beds is a layer of the catalyst according to the invention .

The catalyst according to the present invention is generally used in combination with at least one or more catalyst layers wherein at least one or more of all the catalyst layers from the gas inlet to the layer with the highest hot spot contain the catalyst according to the invention, V ₂ O vanadium pentoxide represented by ₅₁ to 40% by weight, 50 to 99% by weight of titanium dioxide represented by TiO _2, 1% by weight of an alkali metal compound represented by the alkali metal or less, the phosphorus compound of 1.5% by weight or less represented by P, Sb ₂ O ₃ and at least one mixed oxide of at least one element selected from the group consisting of silver and at least one of the above-mentioned elements, 15 wt% or less of the mixed element oxide, or vanadium and at least one of the above- % Or less.

The catalyst thus used in combination is generally used in the layer located near the gas outlet and also in the layer behind the layer with the highest hot spot, and at least a catalyst not according to the invention based on titanium dioxide / V ₂ O ₅ Does not contain any mixed oxide of silver or vanadium. The catalyst according to the present invention may be excluded from all layers. In this case, the catalysts are generally distinguished from each other depending on the form and content of the mixed metal oxide present in the active material.

Catalysts which are not used in accordance with the invention in combination with the catalyst according to the invention generally have a titanium dioxide content of 60 to 99% by weight, a vanadium oxide content of 1 to 40% by weight, an alkali metal content of 1% , A phosphorus content of 1.5 wt% or less, and an antimony content of 10 wt% or less.

The catalyst of the present invention and the catalyst of the catalyst not in accordance with the present invention may further contain a small amount of an oxidizing compound in order to increase activity and selectivity.

Example

Preparation of Catalyst

The components of the various catalyst suspensions are added sequentially to deionized water as a solution or powder and the resulting suspension is stirred for preferably at least 12 hours. As the supply source for the components contained in the catalyst according to the present invention, anatase type titanium dioxide, V ₂ O ₅ or vanadium oxalate, cesium sulfate, ammonium dihydrogenphosphate, antimony trioxide, bismuth vanadium oxide and vanadium oxide, A mixed metal oxide of tungstic acid silver or other silver and vanadium was used.

The organic binder was then added to the aqueous catalyst suspension in the form of an aqueous dispersion of the vinyl acetate-copolymer and approximately 20 to 25% of the total suspension was further stirred for 30 minutes.

Thereafter, the active material or its precursor compound and the organic binder are mixed and dispersed on an inert carrier (composed of cyclic stearate having a size of 7 x 7 x 4 mm or 8 x 6 x 5 mm) until a predetermined amount of the adhesive-containing suspension is applied. The resulting aqueous suspension was applied by spraying and fired to obtain the active material described in the examples.

The active material content (the ratio of the catalyst active substance not including the binder) is measured after each calcination at 400 ° C for 4 hours, and it refers to the ratio of the catalytic active to the total weight of the catalyst including the carrier in each catalyst layer.

The above-mentioned phosphorus content corresponds to the amount of the phosphorus compound added in preparing the catalyst suspension. It is known to those skilled in the art that the actual phosphorus content in the activator may vary depending on how impure the TiO ₂ used is by the phosphorus compound.

Oxidation reaction

Layer reactor system in which the R1-layer is the closest layer to the gas inlet, and the R4-layer is the &lt; RTI ID = 0.0 &gt; Or R5-layer is the layer closest to the gas outlet.

The reactor was equipped with a thermal sleeve having a diameter of 2 mm with an accessory for temperature measurement in the center. 4 Nm ³ of air was introduced downward through the reaction tube at a bath temperature of 340-380 ° C, and air Nm ³ About 30-70 g of xylene was added dropwise.

For the catalyst performance data measurement, the reaction gas exiting the reaction tube was introduced through an oil-cooled condenser where the resulting phthalic anhydride was completely separated and the byproducts such as benzoic acid, maleic anhydride and phthalide were only partially separated . The raw material-PSA separated from the condenser was melted by high-temperature oil, collected and weighed, and the content of phthalic anhydride was measured by GC-analysis.

The raw material-PSA yields mentioned in the examples were calculated as follows:

Raw material- PSA  Yield (% by weight) = [Raw material - PSA  Quantity (g) x Raw material - PSA  Purity (%)] / [o-xylene inflow (g) x o-xylene purity (%)]

The yield of the solid PSA thus measured is expressed by the raw material-PSA yield, even though the by-products contained therein are excluded, since the PSA purity is generally expressed as the product formed after the pretreatment and the distillation reprocessing. Are also known to those skilled in the art.

Since the conversion of o-xylene in each case is almost 100%, the raw material-yield thus measured is directly related to the selectivity of the catalyst system.

Example  One( Comparative Example ):

Catalyst system  A (4th floor)

This catalyst system is a multi-layer system having substantially four different layers. Each of the laminates of this comparison catalyst contains no mixed element oxide of silver.

Composition (% by weight)
Length The first layer (hot spot)
147cm Second layer
45cm Third Floor
70cm Fourth floor
70cm V ₂ O ₅ 5.0 7.7 8.5 15.0 Sb ₂ O ₃ 2.5 2.2 2.4 0.5 BiVO ₄ 0.31 - - - Cs 0.37 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 TiO ₂ Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% AM ratio 8.3 8.4 8.4 8.0

Air Nm ³ It was tested per the catalyst A described in Example 1 at 50 to 65g of the SBT dropped o- xylene and 4 Nm ³ total amount of air and 344 to 347 ℃ per hour. After the introduction, an average raw material -PSA-yield (based on 100% o-xylene purity) of 113.4 wt% was obtained and the phthalide content in the raw material-PSA was 0.01 wt%.

Example  2 (invention):

Catalyst system  B (4th floor)

Composition (% by weight)
Length The first layer (hot spot)
140cm Second layer
45cm Third Floor
70cm Fourth floor
70cm V ₂ O ₅ 5.0 7.7 8.5 15.0 Sb ₂ O ₃ 2.5 2.2 2.4 0.5 BiVO ₄ 0.31 - - - AgVO ₃ 0.17 - - - Cs 0.40 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 TiO ₂ Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% AM ratio 8.6 8.4 8.4 8.0

Air Nm ³ An o- xylene of 58 to 63g per test was added dropwise and the catalyst B described in Example 2 from the SBT of air and 346 to 352 of the total ℃ 4.0 Nm ³ per hour. After the introduction, an average raw material -PSA-yield (based on 100% o-xylene purity) of 114.0 wt% was obtained and the phthalide content in the raw material-PSA was 0.06 wt%.

Example  3 (invention):

Catalyst system  C (4th floor)

Composition (% by weight)
Length The first layer (hot spot)
140cm Second layer
45cm Third Floor
70cm Fourth floor
70cm V ₂ O ₅ 5.0 7.7 8.5 15.0 Sb ₂ O ₃ 2.5 2.2 2.4 0.5 BiVO ₄ 0.31 - - - AgVO ₃ 0.34 - - - Cs 0.42 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 TiO ₂ Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% AM ratio 8.7 8.4 8.4 8.0

Air Nm ³ An o- xylene of 58 to 65g per test was added dropwise and the catalyst C described in Example 3 in the amount of air SBT and 346 to 347 of the total ℃ 4.0 Nm ³ per hour. After the introduction, an average raw material -PSA-yield (based on 100% o-xylene purity) of 115.3 wt% was obtained and the phthalide content in the raw material-PSA was 0.04 wt%.

Example  4 (invention):

Catalyst system  D (4th floor)

Composition (% by weight)
Length The first layer (hot spot)
145cm Second layer
45cm Third Floor
70cm Fourth floor
70cm V ₂ O ₅ 5.0 7.7 8.5 15.0 Sb ₂ O ₃ 2.5 2.2 2.4 0.5 BiVO ₄ 0.31 - - - Ag ₂ WO ₄ 0.39 - - - Cs 0.40 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 TiO ₂ Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% AM ratio 8.7 8.4 8.4 8.0

Air Nm ³ 57 to 69 grams of o-xylene per hour were dripped and the total amount of air per hour of 4.0 Nm &lt; ³ &gt; per hour and the catalyst system D described in Example 4 at SBT from 346 to 348 deg. After the introduction, an average raw material -PSA-yield (based on 100% o-xylene purity) of 113.9 wt% was obtained and the phthalide content in the raw material-PSA was 0.02 wt%.

Example  5 (invention):

Catalyst system  E (4th floor)

Composition (% by weight)

Length The first layer (hot spot)
8 x 6 x 5mm
140cm Second layer
7 x 7 x 4mm
45cm Third Floor
7 x 7 x 4mm
70cm Fourth floor
7 x 7 x 4mm
70cm V ₂ O ₅ 5.0 7.7 8.5 15.0 Sb ₂ O ₃ 2.5 2.2 2.4 0.5 BiVO ₄ 0.31 - - - Ag ₂ MoO ₄ 0.16 - - - Cs 0.40 0.20 0.10 0.05 P 0.03 0.05 0.05 0.10 TiO ₂ Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% AM ratio 8.6 8.4 8.4 8.0

Air Nm ³ An o- xylene of 52 to 62g per test was added dropwise, and the catalyst E described in Example 5 in the amount of air SBT and 347 to 348 of the total ℃ 4.0 Nm ³ per hour. After the introduction, an average raw material -PSA-yield (based on 100% o-xylene purity) of 114.2 wt% was obtained and the phthalide content in the raw material-PSA was 0.01 wt%.

Example  6 ( Comparative Example ):

Catalyst system  F (5th floor)

Composition (% by weight)
Length The first layer
45cm Second layer (hot spots)
95cm Third Floor
50cm Fourth floor
65cm Fifth floor
70cm V ₂ O ₅ 5.0 5.0 7.7 8.5 15.0 Sb ₂ O ₃ 2.5 2.5 2.2 2.4 0.5 BiVO ₄ 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 TiO ₂ Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% AM ratio 8.8 7.8 8.4 8.4 8.0

Air Nm ³ 58 to 61 grams of o-xylene were dripped and a total of 4 Nm &lt; ³ &gt; of air was added per hour and the catalyst system F described in Example 6 was tested at SBT of 350 to 354 [deg.] C. After the introduction, an average raw material -PSA-yield (based on 100% o-xylene purity) of 113.1 wt% was obtained and the phthalide content in the raw material-PSA was 0.01 wt%.

Example 7 (invention):

Catalyst system  G (5th floor)

Composition (% by weight)
Length The first layer
50cm Second layer (hot spots)
90cm Third Floor
45cm Fourth floor
70cm Fifth floor
70cm V ₂ O ₅ 4.0 5.0 7.7 8.5 15.0 Sb ₂ O ₃ 0.2 2.5 2.2 2.4 0.5 BiVO ₄ - 0.31 - - - AgVO ₃ - 0.17 - - - Cs 0.28 0.40 0.21 0.10 0.05 P - 0.03 0.05 0.05 0.10 TiO ₂ Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% Remaining: Up to 100% AM ratio 6.9 7.8 8.4 8.4 8.0

Air Nm ³ 58 to 75 grams of o-xylene were dripped and a total of 4 Nm &lt; ³ &gt; of air was added per hour and the catalyst system G described in Example 6 was tested at SBT at 348 to 350 &lt; 0 &gt; C. After introduction, an average raw material -PSA-yield (based on 100% o-xylene purity) of 114.8 wt% was obtained and the phthalide content in the raw material-PSA was 0.03 wt%.

The performance data of the catalyst according to the present invention Catalyst system Bath temperature (℃) Φ - raw material - PSA - yield
(After the introduction step) (% by weight) Butylphthalide content (% by weight) of the raw material Φ -PSA A (comparative example) 344-347 113.4 0.01 B 346-352 114.0 0.06 C 346-347 115.3 0.04 D 346-348 113.9 0.02 E 347-348 114.2 0.01 F (comparative example) 350-354 113.1 0.01 G 348-350 114.8 0.03

As can be seen from the comparison of Examples 2 to 5 and Comparative Example 1, silver oxide was used as the raw material supply source for preparing the catalyst suspension for catalyst preparation, and the first layer nearest to the gas inlet portion was used. .

As can be seen from the comparison between Example 7 and Comparative Example 6, when vanadium acid silver in the active ingredient of the hot spot-catalyst layer was used, the selectivity of at least one of the catalyst layers behind the first catalyst layer was increased.

Claims (38)

As a catalyst for forming an aldehyde, a carboxylic acid or a carboxylic anhydride from an aromatic hydrocarbon by a catalytic gas phase oxidation reaction,
Wherein the active substance of the catalyst comprises a mixed element oxide of vanadium oxide, titanium dioxide and silver,
Wherein the silver mixed element oxide comprises the following general formula (I): &lt; EMI ID =
Ag _x M _y N _z O _n (general formula 1)
In this formula,
Ag =
x = 0.01 to 100,
M is an element selected from the group consisting of Li, Na, K, Rb, Cs, P, Mg, Ca, Sr,
y = 0 to 1,
N, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ni, Pd, Cu, Au, Zn, Cd, Sn, Pb, As, Ti, Zr, Hf, Ce, and La,
z = 1,
O = oxygen,
n = a number determined by the bond and frequency of oxygen and other elements in the general formula I,
Characterized in that, when preparing the catalyst, at least one mixed element oxide of at least one silver and at least one silver mixed element oxide precursor compound is used as a feed source,
Wherein the active material comprises from 0.01 to 15% by weight of a silver mixed metal oxide.

The catalyst according to claim 1, wherein the activator comprises 0.01 to 10% by weight of a silver mixed metal oxide. The catalyst according to claim 1, wherein the activator comprises 0.01 to 5% by weight of a silver mixed metal oxide. The method of claim 1, wherein the at least one elemental silver oxide is selected from the group consisting of vanadium, molybdenum, tungsten, niobium, tantalum, chromium, titanium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, gold, tin, zirconium, Wherein the catalyst is a mixed metal oxide with at least one additional element selected from the group consisting of arsenic, cerium, lanthanum, bismuth, hafnium, lead, boron, aluminum, ruthenium, rhenium, palladium and rhodium. delete delete delete delete delete The method according to claim 1, wherein at least one silver used as a feedstock source in the preparation of the catalyst is previously separated from the reaction mixture of the mixed element oxide and the mixed element oxide-precursor compound of the mixed element oxide before use as a feedstock source in the catalyst preparation Characterized in that the reaction mixture is used directly as a feedstock in the preparation of the catalyst.
delete 2. Catalyst according to claim 1, characterized in that the active substance of the catalyst comprises vanadium oxide as a mixed element oxide of vanadium comprising the general formula (II)
M _a N _b V _c O _d (formula II)
In this formula,
As a result, it has been found that the metal complexes of the present invention can be used in the form of a metal such as M, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ni, Pd, Cu, Au, Zn, Cd, Sn, Pb, Ti, Zr, Hf, Ce, and La,
a = 0.01 to 100,
At least one element selected from the group consisting of N = Li, Na, K, Rb, Cs, P, Mg, Ca, Sr, Ba,
b = 0 to 1,
V = vanadium,
c = 1,
O = oxygen,
d = a number determined by the bond and frequency of oxygen and other elements in the general formula II.

delete delete delete delete delete 13. The catalyst according to claim 12, wherein the active substance of the catalyst has the following composition after heat-treating the catalyst at 400 DEG C for a predetermined time:
Vanadium oxide: 1-40 wt% (expressed as V ₂ O ₅ )
Titanium dioxide: 50-99 wt% (expressed as TiO ₂ )
Ag _x M _y N _z O _n : 0-15% by weight (expressed as general formula I of claim 1)
M _a N _b V _c O _d : 0-10 wt% (expressed as the general formula II in claim 12)
Alkali metal: 0-1.0 wt% (expressed as alkali metal)
Antimony oxide: 0-10 wt% (expressed as Sb ₂ O ₃ )
Phosphorus: 0-1.5% by weight (indicated as P) 19. The catalyst according to claim 18, wherein the active material of the catalyst has the following composition after heat-treating the catalyst at 400 DEG C for a predetermined period of time:
Vanadium oxide: 1-20 wt% (expressed as V ₂ O ₅ )
Titanium dioxide: 80-99% by weight (expressed as a TiO ₂₎
Vanadium oxide: 0-5% by weight (expressed as AgVO ₃ )
Tungstic acid: 0-5 wt% (expressed as Ag ₂ WO ₄ )
Molybdic acid: 0-5 wt% (expressed as Ag ₂ MoO ₄ )
Bismuth vanadate: 0-3% by weight (expressed as BiVO ₄ )
Cesium: 0-1% by weight (expressed as Cs)
Antimony oxide: 0-5% by weight (expressed as Sb ₂ O ₃ )
Phosphorus: 0-1.5 wt% (indicated as P). delete delete delete 2. The method of claim 1, wherein the catalyst is applied in two or more different layers in shell form on a carrier, wherein at least one of the layers contains titanium dioxide and vanadium oxide, and one of the other layers Characterized in that it contains, as a raw material source, one silver mixed element oxide comprising additional titanium dioxide and vanadium oxide.
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