DE1205502B - Process for the production of an oxidation catalyst - Google Patents

Description

Process for the preparation of an oxidation catalyst The present The invention relates to an oxidation catalyst consisting essentially of oxides The elements antimony and uranium are used, in particular for catalytic oxidation of olefins, especially to oxygen-containing hydrocarbon compounds, such as unsaturated aldehydes (e.g. the oxidation of propylene to acrolein) for which oxidative dehydrogenation of 1-butene to butadiene and of tert. Arnylenes to isoprene and in the presence of ammonia to unsaturated nitriles (such as oxidation of propylene-ammonia mixtures to acrylonitrile) can be used advantageously.

Various oxidation catalysts are already known. In the U.S. Patent 2,904,580 describes a catalyst made from antimony oxide and molybdenum oxide is in the form of antimony molybdate; also is the use of this Catalyst for converting propylene into acrylonitrile mentioned.

In British patent specification 846 666 a catalyst is described, which consists of an antimony oxide alone or in combination with a molybdenum oxide, tungsten oxide, Tellurium oxide, copper oxide, titanium oxide or cobalt oxide. It is said that this Catalysts are either mixtures of these oxides or oxygen-containing compounds of antimony with the other metal, e.g. B. antimony molybdate or molybdenum antimonate. It also says there that these catalysts for the production of unsaturated Aldehydes such as B. acrolein or methacrolein, from olefins such. B. propylene or isobutene, and oxygen can be used. Similar catalysts, however sulfidic type, are in German Patent 693 985 for hydrogenation reactions described. British patent 876 446 describes catalysts which contain antimony, oxygen and tin and either mixtures of antimony oxides with tin oxides or oxygen-containing compounds of antimony and of tin, such as B. Tin Antimonate.

It is also said that these catalysts are used in the manufacture of unsaturated aliphatic nitriles, such as. B. acrylonitrile, from olefins such as z. B. propylene, oxygen and ammonia, can be used. Oxidation catalysts from oxides of chromium, manganese, vanadium and / or tungsten are in German Patent 415429 described. From the German patent specification 550 933 are catalysts known from phosphates of such metals.

It has now been found that one can essentially consist of oxides of Antimony and uranium existing oxidation catalyst with improved properties can be prepared by in a manner known per se from a solution of water-soluble compounds of antimony and uranium oxides or hydrated oxides of these Elements precipitates or from an aqueous suspension of an oxide or oxide hydrate one of the two elements that is a water soluble compound of the other element contains, an oxide or oxide hydrate of this other element precipitates, the precipitate separated from the mother liquor, dried and the product obtained or a mixture heated from an oxide of antimony and an oxide of uranium to a temperature, those above 2600 C and below a temperature which is harmful to the catalyst where the compounds of the two elements are in such a ratio that the Sb: U atomic ratio in the finished catalyst is in a range from about 1:50 to about 99: 1.

This catalyst can be used for the oxidation of olefins in particular oxygen-containing hydrocarbon compounds, such as. B. acrolein, or oxidative dehydrogenating to diolefins or in the presence of ammonia to unsaturated nitriles, such as B.

Acrylonitrile, can be used.

The nature of the chemical compounds that make up the invention Catalyst is built up is unknown. The catalyst can be a mixture of Antimony oxide or oxides and uranium oxide or oxides. However, it is also possible that the antimony and the uranium with the oxygen to form an antimonate or Uranats have entered into a connection. X-ray examinations of the catalyst system indicate the presence of a structurally common phase of the antimony type, consisting from antimony oxide and some form of uranium oxide. Antimony tetroxide was considered present proven. For the purpose of describing the invention, this catalyst will be used referred to as a mixture of antimony and uranium oxides, which are not called shall mean that the catalyst consists either entirely or in part of these compounds is composed.

The ratio between antimony and uranium in the catalyst system can vary within wide limits.

The Sb: U atomic ratio can range from about 1:50 to about 99: 1 lie. However, optimum catalyst activity is achieved with Sb: U atomic ratios in Range from 1: 1 to 25: 1 obtained.

The catalyst can be used without a carrier and has an excellent activity.

However, it can also be combined with a carrier, and preferably in this case the carrier fabric makes at least 10 to about 90% of the weight of the entire catalyst. Any known carrier material can be used such as B.

Silicon dioxide, aluminum oxide, zirconium oxide, alundum, silicon carbide, Aluminum silicon oxide and the inorganic phosphates, silicates, aluminates, borates and carbonates obtained under the reaction conditions applied when using the catalyst occur, are persistent. Preferably silicon dioxide is used as a carrier.

The antimony oxide and the uranium oxide can be mixed together, or they can be prepared separately and then mixed, or they can be separately or formed together in situ.

As starting materials for the antimony oxide component, for. B. any antimony oxide such as antimony trioxide, antimony tetroxide or antimony pentoxide or Mixtures thereof are used; or it can be a hydrous antimony oxide, Methaantimonic acid, orthoantimonic acid or pyroantimonic acid can be used; or it can be a hydrolyzable or decomposable antimony salt, such as. B. an antimony halide, z. B. antimony trichloride, trifluoride or tribromide can be used; in the end can also include antimony pentachloride and antimony pentafluoride, which are formed in water of the hydrous oxide are hydrolyzable, can be used.

Antimony metal can also be used, with the hydrous Oxide by oxidation of the metal in an oxidizing acid, such as. B. nitric acid, is formed.

The uranium oxide component can be in the form of uranium oxide or by precipitation in situ from a soluble uranium salt, e.g. B. the nitrate, acetate, or a halide, such as B. the chloride, are supplied. Uranium metal can also be used as a starting material can be used, and if antimony metal is also used, the antimony can be used into the oxide and the uranium simultaneously into the nitrate by oxidation in hot nitric acid converted will. A sludge of hydrous antimony oxide that is extracted in situ from the metal in Nitric acid can also be mixed with a solution of a uranium salt, such as z. B. uranium nitrate, which are then added in situ as uranium oxide is precipitated by ammonium hydroxide. The ammonium nitrate and everything else Soluble salts are removed by filtration of the resulting sludge.

From the above it can be seen that, for example, uranium tribromide, Uranium tetrabromide, uranium trichloride, uranium tetrachloride, uranium pentachloride, uranium hexafiuoride, Uranium tetraiodide, uranyl nitrate, uranyl sulfate, uranyl chloride, uranyl bromide, uranium trioxide and uranium peroxide can be used as the starting material for the uranium oxide component can.

The catalytic activity of the catalyst is increased by heating an increased temperature improves. The catalyst mixture is dried in the process and 2 to 24 hours to a temperature of about 260 to 621 "C, preferably from about 372 to 482 "C. If the activity is not sufficient by then, can the catalyst for a further 1 to 48 hours at a temperature above 5380 C, but below a temperature which is harmful to the catalyst and at which it melts or is decomposed, preferably from about 760 to about 1038 "C, in the presence of air or heated oxygen. Usually this limit is not reached before 1095 "C, and in some cases this temperature can even be exceeded.

In general, the higher the activation temperature, the higher the Execution of activation less time required. Whether a sufficient activity for certain reaction conditions is achieved by a stain test with a sample of the material determined. Activation is best done in an open Chamber performed in which air or oxygen can circulate, so that more consumed Oxygen can be replaced again.

The antimony-uranium oxide catalyst according to the invention can by the following empirical formula can be defined: Sb «UsOe where a is a number from 1 to 99, b is a number from 50 to 1 and c is a number representing the average valences of antimony and uranium corresponds in the degrees of oxidation in which they are are in the catalyst according to the empirical formula above. So can the Sb valence between 3 and 5 and the U valence between 4 and 6.

Example 1 A catalyst made from antimony oxide and uranium oxide with an Sb: U atomic ratio of 8: 1 was prepared as follows: 90 g of antimony were dissolved in 375 cc of nitric acid (specific gravity 1.42), and the mixture was heated until the formation of nitrogen oxides ceased. To this solution Then a solution of 40.1 g of uranyl acetate [UO2 (C2H302) 2 - 2 H2O] in 400 ccm Water added. Then 300 cc of ammonium hydroxide solution were added and the filtered sludge washed with three times 200 cc of water.

The filter cake was dried overnight at 1200C, 12 hours long annealed at 427 "C and by heating at 760 "C for 12 hours activated in an open muffle furnace.

Example 2 An antimony oxide-uranium oxide catalyst with a Sb: U atomic ratio of 6: 1 was made in the following manner: 45 g of antimony metal (150 mesh U.S. standard = mesh size about 0.10 mm) were dissolved in 186 ccm nitric acid (specific Weight 1.42) dissolved by heating, heating to boiling until formation of nitrogen oxides had stopped. 26.7 g of uranyl nitrate were added to the resulting solution added dissolved in 200 cc of water. After adding 150 cc of 280/0 ammonium hydroxide solution the sludge obtained was filtered to the mixture and washed three times with 100 ccm of washing water, containing a small amount of ammonia, washed. The catalyst was over Dried overnight at 120 ° C., calcined overnight at 427 ° C. and heated for 12 hours activated to 760 "C in an open muffle furnace.

Example 3 A catalyst containing silica as a carrier was prepared by mixing 60.6 g of the prepared according to Example 2 and activated Catalyst with 198 g of an aqueous silica sol with an SiO2 content of 30.6 ° / o established. The resulting catalyst was taken in an oven at 120 "C Occasional stirring, dried for 3 hours and then overnight at 427 "C annealed.

Example 4 A catalyst containing silicon carbide as a carrier was made by mixing 60 g of the activated catalyst of Example 2 with 60 g of silicon carbide obtained, both products having a particle size that they passed through an 80-mesh screen (U.S. standard = mesh size about 0.17 mm). The mixture was stirred with 400 cc of water and the homogeneous aqueous mixture then dried in an oven at 130 "C overnight with occasional stirring and then annealed at 427 "C for 18 hours.

Example 5 An antimony oxide-uranium oxide catalyst with a Sb: U atomic ratio of 6: 1 was produced as follows: 90 g of antimony metal (particle size smaller than 80 mesh U.S. standard = mesh size about 0.17 mm) were more concentrated in 372 ccm Nitric acid heated until the formation of nitrogen oxides has ended. For this 53.4 g of uranyl acetate, which was partially dissolved in water, were added. water was added to dilute the mixture and then 300 cc of 28% ammonium hydroxide solution fed. The sludge was filtered and the filter cake with three times 300 cc a 0.1% ammonium hydroxide solution. After the last wash it was Air sucked through the filter cake for 10 minutes. The catalyst was then dried at 130 "C, annealed at 427" C and then heated to 760 "C in one open muffle furnace activated.

Example 6 A catalyst which consists of antimony oxide and uranium oxide in one Sb: U ratio of 6: 1 on one Third of its weight in silica as a carrier was made as follows: 90 grams of antimony metal (80 mesh U.S. Standard = Mesh size about 0.17 mm) were in 360 ccm hot concentrated nitric acid (specific gravity 1.42) dissolved, and the mixture was until the completion of the Formation of oxides of nitrogen heated and evaporated almost to dryness. For this 53.4 g of uranyl acetate [UO2 (C2H2O2) 2 H2O] were added with stirring. This mixture was ground in a ball mill for 4 hours. When removing the product 200 cc of water were added from the mill. Then 194 g of an aqueous Silica sol (30.6% Si ° 2) was added. Then 200 ccm 280/0 ammonia was added, the sludge obtained was filtered and treated with three times Washed 100 cc of water. The filter cake was dried at 120 to 130 "C overnight, Annealed at 427 "C for 20 hours and heated to 9820 C for 8 hours in one open muffle furnace activated.

Example 7 A catalyst system consisting of antimony oxide and uranium oxide in a Sb: U ratio of 4.9: 1 to one third of its weight in silica existed as a carrier material was produced as follows: 75 g of antimony metal (80 mesh U.S. standard = mesh size about 0.17 mm) were more concentrated in 275 cc hotter Nitric acid (specific gravity 1.42) was dissolved and the mixture was until Heated to stop the formation of oxides of nitrogen and evaporated to near dryness. 53.4 g of uranyl acetate [UO2 (C2H3O2) 2 2 H2O] were then added to this with stirring. The mixture was ball milled for 4 hours. When removing the Mass from the mill was added to 200 cc of water and then 226 g of an aqueous one Silica sol (30.6% SiO2). 150 cc of 28% strength were then added with constant stirring Ammonia added, the resulting sludge filtered and the precipitate with three times Washed 100 cc of water.

The filter cake was dried at 120 to 130 "C overnight 427 "C for 20 hours and annealed by heating to 9820 C for 8 hours in one open muffle furnace activated.

Example 8 A catalyst composed of antimony oxides and uranium oxides with an Sb: U atomic ratio of 11.7: 1 was prepared as follows: 200 g of antimony metal (smaller than 270 mesh U.S. standard = mesh size 0.05 mm) were heated in 826.7ccm of concentrated nitric acid until all red oxides of nitrogen were aborted. For this purpose, an aqueous solution of 62.9 g of uranyl acetate [UO2 (C2H302) 2 - 2 H2Oj added. The sludge was diluted with about 400 cc of water, and then 500 ccm of 280/0 ammonium hydroxide were added, whereby the pH value was brought to 8. The sludge was filtered and three times 1350 cc 2.5% Washed ammonium hydroxide solution. After the last wash it was 15 minutes long Air sucked through the filter cake. The catalyst was left in an oven overnight dried at 130 "C, then calcined overnight at 427" C and then by heating activated overnight at 760 ° C in an open muffle furnace.

Example 9 A catalyst composed of antimony oxides and uranium oxides with a Sb: U atomic ratio of 6: 1 to one third the weight of the two Oxides on silica as a carrier were prepared as follows: 90 g of antimony metal (80 mesh U.S. standard = mesh size about 0.17 mm) became hotter in 360 cc concentrated nitric acid (specific gravity 4.2) dissolved with heating until the formation of nitrogen oxides had ceased. The mixture was almost up to Evaporated to dryness.

53.4 g of uranyl acetate were then added to this with stirring. This mixture was milled in a ball mill for 4 hours. When removing the 200 cc of water were added to the product from the mill. For this purpose, 194 g of a aqueous silica sol (30.6% SiO2) added. With continuous stirring, 200 cc 28% ammonium hydroxide was added in one shot, and the precipitated sludge was filtered and washed three times with 100 cc wash water. The catalyst became then dried overnight at 120 to 130 ° C in an oven for 20 hours at 427 ° C and annealed by heating to 982 ° C for 8 hours in an open muffle furnace activated.

Example 10 40.02 g of finely divided antimony oxide, which by 120 hours Heating of commercially available antimony pentoxide [Sb2 O5] to 760 ° C was obtained, were thoroughly mixed with 12.43 g of finely divided uranium oxide, and the mixture was heated to 427 ° C for 3 hours and then heated to 940 ° C for 32 hours activated. The catalyst contains antimony and uranium in an atomic Sb: U ratio from 3.26: 1.

The catalysts have been used for the preparation of the following Tables visible products under the reaction conditions given there and used with the results listed there.

The percentage conversions are shown in the tables as follows: 0Io total conversion = 100. (moles of olefin fed) - (moles of olefin recovered) Moles of olefin fed% conversion to diolefin = 100. Moles of diolefin recovered / mole supplied olefins.

Table I. Molar ratio im Output gas percentage conversion per Catalytic temperature Molar volume gate after starting material passage relationship example Butene to air to N2 too H2O ° C total conversion of butadiene 1 butene-1 1: 3: 4: 1 494 to 505 44.5 35.0 1 trans-butene-2 ...... 1: 4: 5.4: 1,500 40.2 23.4 2 trans-butene-2 ...... 1: 7: 0: 1 488 to 500 - 18.4 2 trans-butene-2 1: 3: 4: 1 488 to 500-19.2 2 | Butene-1 ........... | 1: 3: 4: 1 | 494 to 513 | - | 30.8 Table II Total yield in%, Catalyst composition of the tor after end product starting mixture conversion set organic Example in moles ° C% compound Propylene ... 1 NH3 ....... 1.5 2 acrylonitrile .......... air ...... 12 471 to 477 100 76.5 N2 ........ 7 H2O ....... 1 Propylene ... 1 NH3 ....... 1.5 6 Acrylonitrile ........... # Air ....... 12 # 482 91 75 N2 ........ 4 H2O ....... 4 Propylene 1 | . . . || Air ....... 10 6 Acrolein N @ 7 7 449 to 454 96 60.8 H2O ....... 4 Isobutylene .. 1 7 Methacrolein ........ # Air ....... 8 # 427 60.2 52.5 H2O ....... 4 (pressure: 0.28 kg / cm²) Isobutylene .. 1 NH3 ....... 1 7 methacrylonitrile ....... # # 427 71.9 60.0 Air ....... 12 (Pressure: 0.28 kg / cm²) H2O ....... 4

Claims (3)

Claims: 1. Process for the production of an oxidation catalyst, which contains antimony and uranium, characterized in that one is known per se Way from a solution of water-soluble compounds of antimony and uranium oxides or oxydhydrates of these elements precipitates or from an aqueous suspension of one Oxyds or Oxydhydrates one of the two elements that are a water soluble compound of the other element, an oxide or oxide hydrate of this other element precipitates, the precipitate is separated off from the mother liquor, dried and the product obtained or a mixture of an oxide of antimony and an oxide of uranium at one temperature heated, the above 260 "C and below a damaging for the catalyst lichen Temperature, whereby the compounds of the two elements in such a Ratio sets in that the Sb: U atomic ratio in the finished catalyst in ranges from about 1:50 to about 99: 1. 2. The method according to claim 1, characterized in that the Connections of the two elements are used in such a ratio that the Sb: U atomic ratio in the finished catalyst in a range from about 1: 1 to about 25: 1. 3. The method according to claim 1 or 2, characterized in that the catalyst is applied to silicon dioxide as a support. Considered publications: German Patent Specifications No. 415 469, 550 933, 693 985.