DE1593269A1 - Process and catalyst for the oxidative catalytic dehydrogenation of hydrocarbons - Google Patents

Description

Process and catalyst for oxidative catalytic dehydrogenation of hydrocarbons The invention relates to oxidative dehydrogenation of hydrocarbons for the production of unsaturated hydrocarbons and the like, especially the dehydrogenation of alkyl aromatic compounds too unsaturated alkyl aromatics in the presence of oxygen, whereby the exothermic Nature of the reaction so much heat is generated that that is usual for dehydration required external heat is reduced. To speed up dehydration new catalysts are used in the process according to the invention, the excellent Ensure selectivity and excellent sales.

It is known that ethylbenzene compounds form styrene at normal pressure Can be dehydrated by Wäurem is supplied from the outside so that the reactants to the reaction temperature, which is usually from -600 to 6500 C, brought will. In one of the known methods, superheated steam is 6 to 10 mol Ethylbenzene mixed to lower the partial pressure of the hydrocarbon, heat to feed for the endothermic reaction and usually that deposited on the catalyst Coke by the water gas reaction to remove.

The overheated steamer mixed with the ethylbenzene usually has a temperature of about 7100 a, while the ethylbenzene is preheated to 5000 C. The mixture enters a fixed bed reactor above 600 to 620 ° C. The inlet temperature however, it becomes common as the age of the catalyst increases and the activity of the catalyst decreases increased to 660 ° C. The heated ethylbenzene is at a space velocity from about 0.7 to 1.0 part by volume per part by volume of catalyst per hour, based on the liquid state and calculated under normal conditions, passed through the reactor.

The reaction products leave the reactor at 560 ° a, are cooled, passed through a trickle tower and condensed in a heat exchanger. The so obtained water and oil phases are separated in a sedimentation vessel, while not Condensed gases are compressed and suddenly cooled for maximum recovery of aromatic hydrocarbons formed as by-products.

In a conventional or non-oxidative dehydrogenation process, the Insert preheated slightly above the reaction temperature. The greater part of the conversion takes place in the inlet part of the catalyst bed, since the reaction is endothermic and the reactants increasing as they travel along the catalyst bed get cooler. This type of temperature profile has one due to two effects result in poor efficiency. At these lower temperatures the speed is with which the ethylbenzene reacts, naturally low. It also becomes the balance less favorable for the dehydrogenation reaction at low temperature. With this procedure sales are therefore severely limited. When the temperature in the entry part of the bed is increased, cracking and coking sharply increase and prevent working without regeneration. A regulation of the temperature in the vicinity of the exit part of the catalyst bed by supplying heat from the outside is not easy.

Liquid heating media are not stable at these high temperatures, and precise regulation by gaseous media is difficult.

The catalysts generally used consist of the oxides of iron, potassium, magnesium and copper. Other commercially available catalysts contain iron oxide with potassium carbonate and chromium oxide as activators. Further be Calcium nickel phosphate catalysts are used for this purpose. Become common these catalysts do not regenerate and have a lifespan of about 1 year. Catalysts and working conditions are advantageous for technical operation those a selectivity of 85 ffi or more and a total conversion of 50% or more can be achieved, but these requirements are not always achieved. In the In large-scale practice, turnover values of only 35-40% are typical.

The chemistry of dehydrogenation, illustrated by the production of styrene by the dehydrogenation of ethylbenzene, can be demonstrated to the test by the following equilibrium reaction: H Oa2E5 C1 C to3 CH3 + H2 It can thus be seen that the conversion is limited by chemical equilibrium. With this limited conversion of the feedstock, recycling of the ethylbenzene is necessary, which means that expensive separation devices are necessary.

More effective methods are aimed at removing hydrogen in order to shift the equilibrium, which favors the formation of the unsaturated hydrocarbon. Oxidative dehydrogenation reactions, in which oxygen is added to the system in the presence of a suitable catalyst, avoid the equilibrium constraint imposed on the dehydrogenation reaction, as illustrated by the following reaction 1/2 02 H. C 02H5 catalyst> Ca = OH2 + H20 In this way, higher conversions to alkylbenzenes, such as styrene, are possible without extensive recycling of the ethylbenzene.

So far, there are basically two types of oxidative dehydrogenation systems known. In one of these systems, ethylbenzene and oxygen are in the presence of a halogen, such as iodine, bromine or chlorine. Generally will. also a solid catalyst used. In the other system, oxygen is the one introduced Hydrocarbon added in the absence of added halogen. This reaction is also carried out in the presence of a solid catalyst. The former The process is ethylbenzene in the presence of liquefied lithium iodide in styrene at conversion temperatures of 5430 C and an oxygen / ethylbenzene ratio of 0.45 to give a liquid product containing 23% ethylbenzene and contains 77% styrene.

The lithium oxide is then converted into lithium oxide by oxidation and iodine converted. The iodine formed causes dehydration, in which hydrogen iodide occurs as a by-product.

Hydrogen iodide and lithium oxide then react to form of the lithium iodide used as the starting material.

The iodine catalyst is thus formed in situ. The catalyst and however, molten lithium iodide and lithium oxide are extremely corrosive and consequently difficult to handle.

In the second method, methylstyrene and styrene can be present in the presence of gaseous iodine by converting isopropylbenzene and ethylbenzene to an extent of 36% resp.

29% with selectivities of about 40% at 700 ° C and a ratio of oxygen sum feedstock of 0.5 can be produced. Be with the styrene however, halogen-containing compounds are also formed because of the difficulties the purification of the unsaturated hydrocarbons formed are undesirable. Furthermore, this process is characterized by the relatively low yields obtained technically disadvantageous.

In a system that works without halogen, styrene is converted from ethylbenzene produced by catalysis with carcium nickel phosphate at 500 ° C. Sales too Styrene can be experienced at diesm by adding 0.15 moles of oxygen per mole of the added ethylbenzoils can be increased from 36% to 45%.

However, the selectivity decreases from 88% to 86%. By adding Oxygen to the feedstock at higher temperatures, the selectivity is still worse. Because of this and because of the maximum sales of 45%, this process is possible undesirable from a technical point of view.

The catalyst iodide used in the known processes precursors, like linthiumoxy / lithium iodia in a molten state, are corrosive due to their Nature difficult to handle. With halogen catalysts or those working with halogen The process encounters the difficulty of halogen contamination of the unsaturated products on. In addition, some of these processes have sales below 505 and the selectivities below 85, which makes these processes technically disadvantageous. In addition, the known systems by the supply of heat from the outside to Triggering and maintaining dehydration marked.

The invention relates to a catalyst using a new catalyst carried out new process for the oxidative dehydration of alkyl-eyoloaliphatisohen and alkyl aromatic organic compounds with selectivities of 85% and more and sales of 50% and more in the case the formation of styrene and with conversions of at least 25 0 and selectivities of 50% in the case of formation of styrene derivatives. The invention is also related to the oxidative dehydrogenation of alkyl aromatic compounds for the production of styrene, and its homologues and analog connections directed. In this process, the reactor temperature with minimal input of heat as well as a balance between the absorbed and maintain the heat generated in the oxidative dehydrogenation reaction. The process is carried out using a catalyst that is proportionately easy to manufacture and use and is halogen-free.

According to the invention, organic compounds of the formula where R is any organic compound or hydrogen, n = 1-3 and Y = methyl or hydrogen, or of the formula where X is an aromatic or heterocyclic compound, n is a number from 1 to 3 and Y is methyl or hydrogen, dehydrogenated with the aid of a new catalyst. The invention is particularly directed to the oxidative dehydrogenation of the abovementioned compounds, especially of organic precursors of styrene, its homologues and analogous compounds which come under the above formulas. Furthermore, any combinations of the aforementioned reactants are suitable for the purposes of the invention.

A particularly important embodiment of the invention is dehydration from ethylbenzene to styrene and from isopropylbenzene to α-methylstyrene or the Preparation of their homologues and analogous compounds by dehydrating their hydrogenated ones Preliminary stages.

The reaction is carried out using a catalyst of the oxides of niobium in combination with the oxides of chromium or tungsten and optionally contains at least one oxide of alkali or alkaline earth metals. Of the Catalyst can per niobium atom 0.05 to 10.0 atoms of chromium or tungsten and 0.01 to Contains 2 atoms of alkali or alkaline earth metal.

The catalyst can be unsupported or on an inert support, such as molten aluminum oxide, silicon carbide, aluminum oxide or silica gel etc., layered or pills 0 The catalyst can be in the form of granules or / used in a fixed bed reactor or in powder form in a fluidized bed reactor will.

The catalyst used in the present invention can thereby have the formula M6 / X03 Nb205 A2 / yO with metal atom ratios of 0.05 to 10: 1: 0 to 2 where M is chromium and / or tungsten, x is the valence of M, A at least one Alkali or alkaline earth metal and y is the valence of A.

The reaction takes place at temperatures from 400 to 7500, C and oxygen / hydrocarbon molar ratios from 0.05 to 1.0, in particular 0.7 to 2.8 parts of liquid space, hydrocarbon feed carried out per hour per space part catalyst.

The oxygen is usually added in the form of air, however can also be pure oxygen or oxygen in combination with a diluent Gas can be used. All of the oxygen-containing gas can enter the reactor be introduced, or it can reduce the selectivity to carbon oxides at a number of locations along the Blown in the reaction zone will.

The concentration of the hydrocarbon in the total feed to the reactor can be between 1 and 50 mol-, but usually about 10 to 20 mol- used. The concentration of the hydrocarbon in the total use of the reactor can be adjusted by adding steam.

The conversion of the hydrocarbon can be carried out by a mixture of hydrocarbon, oxygen and diluent 10 minutes to The catalyst zone is fed for 10 hours, followed by the feed of the mixture interrupted and the catalyst is regenerated with supply air, whereby carbon deposits can be removed as carbon oxides on the catalyst. It is also possible to do the hydrocarbon conversion to carry out without regeneration, the mixture of hydrocarbon, oxygen and diluents continuously in the catalyst zone without intervening Regeneration is supplied. If you work without regeneration, it is in generally advantageous to add steam as part of the inert diluent use.

The hydrocarbon feed and the oxygen are prior to the introduction mixed in a reaction chamber in the appropriate molar ratio, or they can be separated to be introduced. The components can be introduced into the catalyst chamber before introduction heated with steam or other heat sources. It is also possible that Bring the reactants together with the catalyst at ambient temperature and supplying heat to the reaction chamber. The exothermic nature of oxidative dehydration, the formation of water as one of the by-products enables the implementation der-reaction with less supply of "external heat". The heat of reaction, ' the hydrogen formed as a by-product of the reaction during the oxidation arises. is used to heat the carbon dioxide together with externally supplied heat at the reaction temperature to keep out the dehydration is required.

During the usual procedure through reaction and equilibrium considerations is limited, the method according to the invention enables the temperature to keep it almost constant in bed, with high speeds being achieved and Equilibrium restrictions eliminated by converting hydrogen into water will.

It was found that using the above new catalyst in the process according to the invention, the activation energy for the oxidative dehydrogenation of hydrocarbons is much lower than in the non-oxidative process. For example, in the case of ethylbenzene, the activation force is for the reaction in the absence of oxygen 29.1 kcal. The activation energies for the oxidative dehydrogenation of ethylbenzene using oxygen / ethylbenzyl ratios of 0.17, 0.25 and 0.50 is 22 kcal. In this plague it is important that the invention is the oxidative dehydrogenation of various hydrocarbons with considerably less heat input than with the previously known methods and thus a considerable fuel saving, especially in large-scale operation enables.

The catalysts used in the present invention are prepared as follows : Appropriate amounts of precursor compounds # soluble # catalytic oxides are reacted in solution until a precipitate has formed, which calcines will. The calcined precipitation can be carried out with K2O or other oxydene precursors of alkali and / or alkaline earth metals, e.g. an aqueous solution of potassium hydroxide, alcohol, ischem Potassium hydroxide or the like, further treated when catalysts are produced supposed to contain potassium.

Suitable alkali metals for this are Li, Na, K, Rb and Cs, while as alkaline earth metals Ca, Sr and Ba come into question.

Other elements of main group I and II, e.g. B. H, Fr, Bo Mg and Ra, which correspond to the aforementioned alkali and alkaline earth metals, can also be used. Any combination of the foregoing Alkali and / or alkaline earth metals, in addition to any combinations of the above elements mentioned are needed. The aforementioned alkali and alkaline earth compounds are hereinafter referred to as "aluminum potassium compounds". The precipitates thus treated are calcined a second time. The metal oxide precursors are advantageously ammonium hydroxide added to adjust the pH to facilitate precipitation.

The precursor compounds of the oxides mentioned are generally those organic and inorganic salts of the catalyst metals, e.g. the nitrates and Oxalates of chromium and niobium, or ammonium salts of the catalyst metals, e.g.

Ammonium tungstates or chromates are possible. Other precursor compounds of metal oxides are also suitable as long as they are soluble. For example W203.Nb205 catalysts are made from ammonium metatungstate and niobium oxalate and Cr203.Nb205 catalysts are made from ammonium dichromate or chromium nitrate and Manufactured niobium oxalate.

The reaction can be carried out in such a way that the triggering of the Dehydration, the amount of externally supplied heat is inversely proportional to the amount of dehydration The amount of oxygen used can be reduced. This relationship is for the purposes of the invention are defined as the percentage heat balance "i.e. that for ethylbenzene and its equivalents mentioned here required percentage of endothermic Heat of dehydration, which is added by the heat generated during the union of hydrogen formed as a by-product is released with oxygen.

For example, the heat balance can be from 0 to 20%, preferably vary from 20 to 180 ffi or from 50 to 150 ffi.

20 to 180 ffi heat balance correspond to about 10 to 90% conversion of hydrogen with oxygen in the case of ethylbenzene as input material, and 50 to 150% heat balance correspond to about 25 to 75% conversion of the hydrogen.

Likewise, 0 to 200 ffi heat balance indicate that the reaction can be carried out without oxygen or with so much oxygen that the entire The hydrogen released during the reaction is converted into water. The heat balance is thus partly controlled by the addition of oxygen, and this addition of oxygen can be expressed as a heat balance, i.e. 0 to 200%, 20 to 180% and 50 to 150% will.

The hydrocarbon conversions and selectivities varied sb that in the production of styrene conversions of at least about 50% 0 with selectivities of at least 85% can be achieved. The transformations of hydrocarbons into Styrene derivatives are at least 25 5% with selectivities of at least 50%.

The various catalysts used for the dehydrogenation of hydrocarbons are used in detail, along with various conversion methods described in the following examples of preferred embodiments of the invention. Unless otherwise stated, nitrogen is used. as a diluent gas in all examples is used, and all 1Ratios11 are molar ratios.

Examples 1 and 2 tungsten-niobium catalysts.

Catalysts containing tungsten and niobium are made by Misohening solutions of ammonium metatungstate and niobium oxalate to evaporate the excess Water, drying and calcining at 5000 a. In this way, x become catalysts with W / Nb ratios of 0.8 to 8.5.

The conversion of ethylbenzene using these catalysts is at Temperatures of 675 and 7000 C, a space flow velocity from 1.3 V / V / h and O 2 / ethylbenzene ratios of 0.25 and 0.50. the Conversions and selectivities obtained at 675 and 7000 C are given below: 67500 7000C Um- Selek- Um- Selek-Example- Kataly- 02 / EB * set activity set activity game sator -I 1.0 WO3.0.6 Nb2o5 0.25 47 84 56 83 II 1.0 W03.1, O Nb205 0.25 43 83 54 83 * EB = ethylbenzene From the above values it can be seen that with tungsten-niobium catalysts Conversions of 43 to 56% and selectivities of 83 to 84% can be achieved. Catalysts with W / Nb ratios of 1.0 and 0.5 are similar in both activity as well as selectivity. Tungsten-niobium catalysts have roughly the same activity but surprisingly a higher selectivity than iron-niobium catalysts.

EXAMPLES III - VI Chromium-Niobium Catalysts Two series of chromium-niobium catalysts are produced. In the first row are solutions of ammonium dichromate and Niobium oxalate mixed, whereupon the excess water is evaporated. The solids are dried and calcined at 7500 C. This way they become catalysts made with Cr / nb ratios of 0.2, 0.33, 0n5 and 1.0.

The conversion of Ethylebzene (EB) with these catalysts will at temperatures from 650 to 7000 c, room flow velocities from 1.0 to 1.3 V / V / h and O2 / ethylbenzene ratios of 0.15 to 0.90 made, The Conversions and selectivities achieved at 7000 C are given below.

Secondary catalytic converter room airflow O2 / Eb 700 ° c clearance speed Um- Selektivi-V / V / std. rate, rate,% 5 III 1.0 Cr2O3. 1.3 0.25 45 83 5 Nb205 IV 1.0 Cr203. 1.0 0.25 59 85 3.0 Nb205 V 1.0 Gr2030 1.2 0.25 58 84 2, Nb2O5 VI 1.0 Cr2O3. 1.5 0.25 43 92 1.0 Nb2O5 With catalysts in which the ratio Cr / Nb 0.33 and Is 0.50, thus conversions of about 59% and a selectivity of 84 to 85% received. For catalysts with Cr / Nb ratios of 0.2 and 1.0, the Sales lower and the selectivities somewhat lower. Chromium-niobium catalysts, which are made using ammonium dichromate solution are of concern Activity and selectivity comparable to tungsten-niobium catalysts, example VII A second set of chromium-niobium catalysts is made as follows: One Ammonium hydroxide solution is added to a solution of chromium nitrate and niobium oxalate. The precipitate which separates out is filtered off, dried and caloiniert at 5000 a. In this way a catalyst with a Cr / Nb ratio of 1.67 is obtained.

The conversion of ethylbenzene with this catalyst is carried out at temperatures from 625 to 725 ° C, room flow rates from 0.7 to 2.8 and O2 / ethylbenzene molar ratios from 0.15 to 0.50 carried out. The conversion and selectivity at 7000 C are shown below specified.

700 ° C catalyst room flow 02 / EB conversion, selectivity flow rate, V / V / h

1.0 Cr203 1.2 - 1.4 0.25 63 82 - 85 0.6 Nb205 The activity of aus Chromium nitrate produced chromium-niobium catalysts increases when the Cr / Nb ratio increases from 5.0 to 0.5 decreases, while the selectivity of all catalysts with these variable molar ratios in the range from 79 to 85%.

The activity and selectivity of chromium-niobium catalysts made from Ammonium dichromate and chromium nitrate are produced, indicate that the The catalyst made from the nitrate is more active than the catalyst made from the dichromate getting produced. The highest activity in the nitrate range of catalysts is achieved in the composition range, the Or / Nb ratio from 0.6 to 1.0 is equivalent to.

Quite generally, the styrene selectivity of catalysts is made from the dichromate or chromium nitrate can be produced similarly if the comparison is made conatant temperature and constant room flow velocity is carried out.

However, the catalyst made by the nitrate method is general more selective than the catalyst made with dichromate when the two are at constant Sales are compared.

Example VIII A Commercially Available Calcium-Nickel-Phosphate Catalyst was used for the oxidative dehydrogenation of ethylbenzene at temperatures of 650 and 7000 C are used. If there is no oxygen in the feedstock (reactant) was added, the conversion was 20% and the selectivity to styrene at 650 ° C 92. By adding oxygen to the feedstock according to an oxygen / ethylbenzene ratio from 0.5 at 6500 ° C., the conversion rose to 44%, but the selectivity to styrene fell from 92% to 83%.

At 7000 C and an oxygen / ethylbenzene molar ratio of 0.5 a conversion of 55 and a selectivity of 85% was achieved.

Examples IX and X It has been found that a potassium hydroxide treated chromium-niobium catalyst compared to similar catalysts that contain no potassium, hydrocarbons, such as ethylbenzene, at temperatures below 7000 C with the formation of a minimal amount of cracked products and coke in ethylbenzene converts.

A catalyst is produced as follows: An ammonium hydroxide solution is added to a solution of chromium nitrate and niobium oxalate. The precipitate obtained is filtered off, dried and calcined at 5000C. A solution of potassium hydroxide in water is then added to the precipitation, whereupon it is dried and calcined again will. The catalyst produced in this way contains Cr2o3.Nb2O5.K2O in a molar ratio of 1: 1: 0.2.

The catalyst produced in this way, which contains the oxides of, niobium, chromium and Contains potassium, is used to convert ethylbenzene into styrene. the Conversion conditions and results are shown below: catalyst 1.0 Cr2O3.1.0 Nb2O5.0.1 K2O temperature, ° C 700 650 air flow velocity, r / v / h 0.7 0t6 02 / ethylbenzene molar ratio 0.2 0.2 conversion,% 83 67 selectivity to in ß styrene 59.8 89.9 benzene + toluene 25.0 5.5 coke 11.3 3.5 C1-C3 2.8 0.3 CO 2 + CO 1.1 0.8 The above results indicate that Chromium-niobium catalysts that contain potassium oxide, not just about twice as much are active like the calcium-nickel-phosphate catalysts according to Example VIII, but even at 6500 C a conversion of 67 r ethylbenzene to styrene with a selectivity on 90% gave, while with the calcium ~ nickel-phosphate catalysts the selectivity only 80% under comparable conditions. The one described above The conversion achieved by the chromium-niobium-potassium catalyst is approximately 1.5 to 2 times of the turnover that is achieved in large-scale operations. It is therefore evident that this new catalyst and the process according to the invention have a significant impact mean technical port step.

Example XI The following examples illustrate the space velocity, which is required to achieve a conversion of 85% ethylbenzene with a catalyst which contains 1.0 Cr203 and 1.0 Nb205. The attempt was made on the in Example 1 described manner carried out. ' The results given below were received.

Space flow rate required for 85% conversion, V / V / hour.

O2 / ethylbenzene ratio 0 0.25 0.50 Temperature, ° C 700 0.79 0.83 0.95 650 0.37 0.43 0.53 600 0 ', 15 0.22 0.30 The table above shows that at 7000 C by the addition of 0.5 mol of oxygen the catalyst activity in comparison to operate without the addition of oxygen by about 20. The catalyst activity increases at 600 ° C by adding 0.5 mol of oxygen by 100%.

Example XII Chromium-Niobium Catalysts Containing an Alkali Metal Oxide are produced as follows: A chromium-niobium catalyst is mixed with a solution of a Treated with alkali salt. The impregnated catalyst is dried and at 5000 C calcined. The catalysts produced in this way contain Cr2O3.Nb2O5.K2O, Cr2o3.Nb2O5.Rb2O and Cr2o3.nb2O5.Cs2O in a molar ratio of 1.1 t 1.0: 0.175.

The conversion of ethylbenzene with these catalysts is at a Temperature of 6500 0, a space flow velocity of 0.60 (based on Liquid state), an O2 / ethylene molar ratio of 0.20 and an ethylbenzene concentration made in the feed of 10%. The diluent used is nitrogen or Steam used.

The conversions and selectivities achieved are indicated below Cat lyser Cr2O3.Nb2O5. Cr2o3.nb2O5. Cr2O3.Nb2O5.

0.175 K2O 0.175 Rb2O 0.175 Cs2O diluent N2 steam N2 steam N2 steam temp., ° C 650 650 650 650 650 650 Room air velocity 0.6 0.6 0.6 0.6 0.6 0.6 02 / ethylbenzene molar ratio 0.2 OS2 0.2 0.2 0.2 0.2 conversion,% 65 57 74 67 41 52 styrene selectivity,% 86 85 82 84 86 80 Example XII = I This example clearly illustrates the beneficial effect of oxygen in the feed material With a Katabei 650 ° C lystator made of Cr2O3.nb2o5.0,18 Rb2O were / with Ethylbenzene as feed at 0.6 V / V / hour. and a concentration of the hydrocarbon in the feed of 10 mol% and water vapor as the diluent, the following Get values: oxygen / ethylbenzene ratio 0 0.2 conversion of ethylbenzene, % 36.7 67 selectivity,% syrene 83.8 83.8 benzene + toluene 10.2 11.8 coke 3.2 0.32 The conversion is increased by introducing the oxygen into the ethylbenzene used thus almost doubled and the selectivity to styrene kept at 83.8%. the Coke formation is reduced to a tenth.

Example XIV A granulated catalyst of the composition 1CrO3.2 Nb2O5.0,35 K20 is used for the oxidative dehydrogenation of ß-ethylnaphthalene (hereinafter referred to as EN). The following reaction conditions according to the invention are used: Temperature 6250 C room air flow velocity 0.8 V / V / hour

02 / EN molar ratio 0.4% ß-thylnaphthalene in use 12% (water vapor as diluent) The conversion of ethylnaphthalene is 46%, the selectivity for ß-vinylnaphthalene 81. The selectivity value for CO + C02 formation is 7%.

Example XV Heterocyclic ethyl compounds are tested of a supported catalyst applied to a-aluminum oxide for oxidative dehydrogenation used. The catalyst has the composition Cr2o3.4 Nb205. 0.15 K20. the The following reaction conditions according to the invention are used: Space flow rate 0s8 V / V / h.

Concentration of the organic compound in use 10% (water vapor as diluent) O / heterocyclic compound molar ratio 0.25 The following Results are obtained: Compound Optimal Conversion Selectivity,% Temp., ° C % heterocyclic CO + CO2 vinyl compound 2-ethylpyridine 625 51 81 6 2-ethylthiophene 585 74 69 22 There is no sign of catalyst poisoning.

Example XVI A feedstock comprising a mixture of 'm + p-diethylbenzene contains, is over the catalyst described in Example II the Composition 1.0 WO3.1.0 Nb205 dehydrated.

The conversion with this catalyst is carried out at 675 and 700 ° C, one Room flow rate of 0.6 V / V / hour. and an O 2 / diethylbenzene molar ratio performed by 0.52. The following results are obtained: Temp., ° C turnover, % Selectivity, 5 divinhylbenzene ethylvinylbenzyl 675 47 31 57 700 61 61 21 The above examples describe the conversion of organic compounds by oxidative dehydrogenation, however, the conversion of other compounds also falls within the scope of the invention. Examples of such compounds include: methane, Ethane, ethylene, propane, propene, n-butane, butene, isobutane, n-pentane, 1-pentene, 2-pentene, Isopentane, 3-methyl-2-butene, n-hexane, hexene, n-heptane, monomethylhexane, monomethylhexene, n-octane, n-octene, monomethylheptane, dimethylhexane, n-decane, 5-methylnonane, 2,2,3-trimethylpentane, 2, 4, 4-rYrimethylpentene, cyclopentane, cyclopentene, methylcyclopentane, cyclohexane, Methylcyclohexane, ethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane and n-propylbenzene.

A new process for the oxidative dehydrogenation of the various. organic compounds using a new catalyst described. A preferred catalyst for carrying out the reaction contains a mixture of the oxides of chromium or tungsten, niobium and potassium.

The selectivities and conversions achieved with this new catalyst are higher than can be achieved with known processes and catalysts. The reaction is further characterized as being sufficiently exothermic to the total amount of externally supplied to maintain the reaction temperature to reduce the heat required.

Claims (1)

P atent claims 1.) Process for the oxidative dehydrogenation of hydrocarbons of the general formulas in which R is hydrogen or an organic radical, Y hydrogen or methyl, X is an aromatic or heterocyclic radical and n is a number from 1 to 3, characterized in that the dehydrogenation is carried out in the presence of oxygen and in the presence of a catalyst which contains the oxides of niobium, chromium and / or tungsten and optionally alkali and / or alkaline earth oxides, and initially only supplies as much external heat as is necessary to initiate the reaction, and then supplies less external heat than is necessary to maintain the reaction. 2.) Process according to claim l, characterized in that at Temperatures between 4000 and 7500C works. 3. ') Method according to claim 1 or 2, characterized in that one with oxygen / hydrocarbon molar ratios of 0.05 to 1.0, in particular 0.7 to 2.8 liquid volume parts of hydrocarbon per hour per volume of catalyst works0 4.) The method according to claim 1 to 3, characterized in that the Oxygen in pure form or in the form of air or in combination with a diluting agent Gas used. 5.) The method according to claim 1 to 4, characterized in that the introducing oxygen at various points along the reaction zone. 6.) Method according to claim 1 to 5, characterized in that the raw hydrogen in a concentration of 1 to 50 mol%, preferably from 10 to 20 moles is used. 7.) The method according to claim 6, characterized in that the Adjusts hydrocarbon concentration using water vapor. 8.) Method according to claim 1 to 7, characterized in that the hydrocarbon and oxygen are introduced separately into the reaction zone. 9.) Method according to claim 1 to 7, characterized in that one hydrocarbon. and mixing oxygen prior to introduction into the reaction zone. 10.) Method according to claim 1 to 9, characterized in that a catalyst of the general formula M6 / x03 .Nb205 OA2 / yO with metal atom ratios from 0.05 to 10: 1 r O to 2 used, where M is chromium and / or tungsten, x is the valency of M ,, A at least one alkali or alkaline earth metal and y is the valence of A means. 11.) The method according to claim 1 to 10, characterized in that the amount of heat supplied from outside to initiate the reaction is inversely proportional reduced to the amount of oxygen used. i2.) Procedure according to claims 1 to 11, characterized in that dehydrogenation is carried out discontinuously and regenerates the catalyst with air. 13.) Dehydrogenation catalyst in the form of gray matter, powder or applied on a carrier, characterized by the general formula M6 / x93 .Nb205.A A2 / y with metal atom ratios of 0.05 to 10: 1: 0 to 2, where M is chromium and / or tungsten, x the valence of, M, A at least one alkali or alkaline earth metal and y the Valence of-A means. 14.) A method for producing a catalyst according to claim 13, characterized in that metal compounds, the catalytic oxides result until precipitation. converts, calcines the precipitate, then optionally with an alkali or alkaline earth oxide or a compound forming these oxides treated and the product calcined again. 15.) The method according to claim 14, characterized in that as Metal compounds, organic and / or inorganic salts of the catalyst metals used. 16.) Method according to claim 14 and 15, characterized in that nitrates, oxalates or ammonium salts of the catalyst metals are used. 17.) The method according to claim 14 to 16, characterized in that the precipitation is effected in the presence of ammonia.