DE2729841A1 - (Meth)acrolein prodn. process - by oxidn. of propylene or isobutylene using a catalyst contg. oxides of cobalt, iron, bismuth, molybdenum, potassium and opt. silicon - Google Patents

Abstract

Oxidn. catalysts for oxidising 3-6C olefins to the corresp. unsatd. aldehydes, esp. for oxidising propylene and isobutylene to acrolein and methacrolein, contains oxides of Co, Fe, Bi, Mo and K in an atomic ratio Co4.5-7.0Fe1-2Bi1-2Mo15K0.05-0.2. The catalysts give very high (70-90%) conversion of the olefin with high selectivity (85-95%) to the prodn. of the desired unsatd. olefin. Use of the remaining oxidn. prods. (mainly (meth)acrylic acid, CO and CO2) in a recycle stream as a diluent for the oxygen improves the conversion of propylene to about 99% and the selectivity to acrolein to up to 97%.

Description

Catalyst and process for the production of acrylic

acid from propylene The invention relates to a process for oxidation from olefins, especially propylene, to the corresponding aldehydes, oxidation from acrolein to acrylic acid and certain catalysts that work with the corresponding Procedures are used.

The main processes for the production of acrolein are based on the conversion of propylene by partial oxidation reaction over a suitable one Catalyst.

With some catalysts you get a mixture of acrolein and Acrylic acid, while others are highly selective for either the aldehyde or the acid are.

Examples of catalysts that are mainly selective for the aldehyde are and that come closest to the catalysts of the invention are those that in US-PS 3,855,308 are described in which cobalt, iron, Bismuth, Tungsten, molybdenum, silicon, thallium and an alkali or alkaline earth metal are used will; and those in US Pat. No. 3,799,978, in which cobalt, iron, bismuth, Tungsten, molybdenum, silicon and an alkaline earth metal can be used. The applicant of both patents is the company Nippon Shokubai Kagaku Kogyo Co. Ltd.

For the production of acrylic acid, the most common methods are used, in which propylene or acrolein is oxidized to acrylic acid. As catalysts Many different mixtures of metal oxides have been used for these processes. Most of these catalysts contain molybdenum oxide as a major component. Some the catalysts are effective in the oxidation of propylene directly in acrylic acid, although this is often a function of the conditions under which the catalysts be used. Others oxidize acrolein to the acid. In all cases, anything can unconverted acrolein or acrolein produced in the oxidation process of propylene is formed into acrylic acid is recycled to the feed stream and then recycled are oxidized with the formation of acrylic acid.

In addition to molybdenum oxide, the known catalysts contain many other metals (usually as their oxides) that have the catalytic effect of molybdenum. The transition metals of group VIII of the periodic table including iron, cobalt and nickel have been used in many such catalysts. Others, chosen from the various groups of metals in the periodic table, were also used. For example, it is known that titanium, vanadium, chromium, Tungsten and Manganese in Groups IVB, VB, VIB and VIIB are useful.

To the best of the applicant's knowledge, U.S. Patents 3,775,474, 3,833 come 649 and 3 886 092 in which the use of Mo, V, Cr, Cu and W is described in various combinations, closest to the subject of the application. However, none of these references mention the use of tantalum, titanium or niobium described, and also contain the catalyst compositions according to the invention not tungsten as referred to in the above three U.S. patents.

Surprisingly, it has been found that with the inventive Catalysts and Processes Improved Reactant Conversions and improved selectivities for the desired products can be obtained. Farther is achieved through the use of a recycle stream as a diluent for the oxygen, the conversion of propylene to about 99% and the selectivity Acrolein up to 97, 'improved. The recycle stream contains essentially Oxides of nitrogen and carbon. The properties of the catalyst make it possible it that the recycle stream can be used in place of steam, whereby both the cost of the steam and the subsequent separation can be saved of the water from the product is not required.

The invention relates to a catalyst for the oxidation of lower Olefins containing 3 to 6 carbon atoms to analogous saturated aldehydes, which contains the oxides of cobalt, iron, bismuth, molybdenum and an alkali metal, the atomic ratios of the metals being within the ranges Co4.4-7.0Fe1-2Bi1-2Mo15K0.05-0.2 lie.

The invention also relates to a carrier containing a carrier Catalyst used for the oxidation of Acrolein suitable for acrylic acid is that of the oxides of molybdenum, vanadium, chromium, copper and at least one oxide contains tantalum, titanium and niobium on an inert carrier, the atomic ratio of the metals Mo15V5-10Cr0.2-2Cu2-5M0.1-3, in which M is tantalum, titanium, niobium or their mixtures means.

The invention also relates to (A) a process for oxidation in the vapor phase of an olefin to an unsaturated aldehyde, which is characterized is that you get a gaseous mixture of the olefin and oxygen together with an inert diluent at an appropriate temperature and contact time passes over a catalyst that removes the oxides of cobalt, iron, bismuth, molybdenum, Contains potassium and optionally silicon, in which the metals are in atomic proportions of Co4.4-7.0 Fe1-2Bi1-2Mo15K0.05-0.2 and, if present, Si1-1.5; (B) a process for the oxidation of acrolein in the vapor phase to produce Acrylic acid, in which a catalyst is used with a carrier that is thereby is characterized in that a catalyst is used which contains metal oxides, the metals being present in an atomic ratio of M ° 15V5-10Crot2 ~ 2CU2 ~ 5 million 1 3 are, in which M is a metal from the group consisting of tantalum, titanium, niobium or their mixtures means; (C) a two-step process for the oxidation of propylene to acrylic acid, which is characterized in that (a) a gaseous mixture of propylene and oxygen together with an inert diluent in one suitable temperature and contact time over a catalyst that conducts the oxides Contains cobalt, iron, bismuth, molybdenum, potassium and silicon, being the metals in atomic ratios of Co4, 4-7, 0Fe1-2Bi1-2Mo15%, 05-0.2 and, if available, Sil, and (b) the effluent from (a) via a carrier containing Conducts catalyst that contains the oxides of metals in atomic proportions of Mo15V5-10Cr0.2-2Cu2-5M0.1-3 are present, wherein M is tantalum, titanium, niobium or their mixtures means.

I. Oxidation of olefins to aldehydes The production of oxidation catalysts, which are used in the process of making acrolein is done by either the aqueous solutions or suspensions of the salts of the metal components the catalysts evaporate to dryness. This can be done in the presence of a carrier for the catalyst, so that the catalytic components are on the support be deposited, or, if a carrier is not used, the resulting Solids are pulverized and then pelletized by compression. A thick slurry or paste of the catalyst ingredients can also be extruded and be cut into pellet form. Finally, the catalytic components with and without support at a temperature of about 300 to 6000C (preferably about 5000C) calcined to form the oxides, which are the catalytic components, used in the process. The original compounds of metals are not important as long as they form the desired oxides on calcination. Once in a while the original metal compounds have such properties that their solutions co-precipitate, the precipitate then being washed and calcined.

Other methods can be used such as co-gelation the various components and subsequent drying of the gel mass in itself known way. The solution or gel can also form a particulate Material which is subsequently compressed in suitable forms or such as it is is used when the particle size is for a liquid bed or

Fluidized bed reactor is suitable to be spray-dried.

The catalyst essentially consists or essentially contains the oxides of the metals cobalt, iron, bismuth, molybdenum, potassium and optionally Silicon, preferably in the form of pellets, although it is aluminum oxide, Silicon carbide or other suitable materials that do not use the oxidation process affect, as a carrier may contain. The use of the catalyst on a Support generally requires higher temperatures to achieve the same Conversions obtained using pellets. If necessary, can Silicon in an amount of about 0.5 to 3.0 atoms in the above compositions be admitted. A particularly preferred catalyst contains the metal in the Atomic ratio of Cog ,, Fe1,1E; Bi1) 3M015KO, 071 where the metals present as oxides.

The advantages of the method according to the invention, in which the preferred Catalysts used are high olefin conversion and high Selectivity to the unsaturated aldehyde in a single pass.

The properties of the catalyst still allow its use of the recycle gas as a diluent, thereby reducing the conversion of the olefin is further improved, and the use of the recycle gas instead of Steam that was used in the known processes, reducing production costs to be humiliated. The method according to the invention also allows use higher pressures, whereby a higher productivity is obtained than with the known ones Procedure.

When preparing the unsupported catalyst, soluble ones will be produced Salts of bismuth, iron and cobalt dissolved together, e.g. nitrates are often used these metals dissolved in an aqueous, acidic solution. The potassium and molybdenum salts are made in separate solutions and then to the solution of the other metal salts given. The molybdenum salt can be ammonium molybdate (NH4) 6Mo7024.4H20 and in technical Form. Potassium is usually added as KOH, although any other soluble potassium salts, e.g. KN03 or KCl, to the ammonium molybdate solution, which is somewhat basic, can be added.

Mixing the nitrates and ammonium salts gives a thixotropic one Solution, and this must be able to form a gel before it is dried and pelletized or it must be able to form a gel on a support and then it is dried. Good blending is essential to avoid premature cel formation and inconsistent Catalyst composition to avoid. After the gel has formed water is evaporated from the mixture until it contains 5 to 25% water. A more preferred one Water content is 8 to 1596.

The resulting mixture is then shaped into pellets and dried and finally calcined at a temperature in the range from 475 to 5300C. at the calcining process, the catalyst is in air for a time from 4 to 8 Heated for hours, gradually increasing the temperature from 200 ° C to 500 to 5300C during the first hour and then a temperature in the range of 500 to 530 ° C is maintained for the remainder of the time.

The resulting catalyst pellets have a porosity of over 60% and contain pores, 90% of which range in size from 0.05 to about 3.0 microns own. The surface area of the catalyst is preferably about 3 to 15 m 2 / g. With a surface area below about 3 m2 / g, the conversion falls below 90%, and with one With a surface above 15 m2 / g, so much CO and C02 is formed that the economy the process is adversely affected.

If catalysts are produced on supports, they are used as supports used, which have a surface area of 0.2 to 2 m2 / g and a porosity, where 9096 of the pores contained therein all range from 50 to 1500 microns in diameter lie.

The catalysts prepared by the process described above are used to produce acrolein from propylene or methacrolein from isobutylene used.

However, other olefins containing up to 6 carbon atoms can to the analogous, unsaturated aldehydes via the catalyst according to the invention being transformed.

The vapor phase process that is carried out over the catalyst of the present invention can be carried out is carried out by adding a gas mixture of the olefin, e.g. propylene, together with oxygen (usually air).

An inert diluent such as steam is generally used. The preferred thinning agent for the process according to the invention is recycled Gas containing nitrogen, carbon monoxide, carbon dioxide, oxygen and argon. An operable feed composition contains 0.2 to 10 vol- 'olefin, 11.8 to 20 vol, 'oxygen and 88 to 70 vol,' diluent gas. Suitable temperatures are those that are in the range of 285 to about 3750C. The contact times can can be varied from 0.5 to 5 seconds, depending on the temperature. Preferred Regions are a feed that is 4 to 8 vol-, 'olefin, 11 to 17 vol-966 oxygen and contains 84 to 75 vol-96 diluents; a temperature of 285 to 3150C and a contact time of 1.8 to 2.8 seconds. In general, by an increase the pressure on the feedstock affects both conversion and selectivity of the catalyst deteriorated. Preferred pressures are 0.7 to 6.0 kg / cm2 (10-85 psig) while the preferred range is 1.76 to 5.30 kg / cm2 (25-75 psig).

Small amounts of unsaturated acid formed in the process are of no importance, as the aldehyde often continues to take the acid Using a catalyst is oxidized, which is responsible for the oxidation of the aldehyde to the analogous acid is highly selective and the by-product acid up to this Second oxidation is carried on and from the effluent therefrom together with the acid formed at this stage is isolated.

If the aldehyde is to be used in other processes in which the Acid would be undesirable, the acid can be removed by simply distilling off the aldehyde, which at considerable boils lower than the acid, be separated.

One of the well-known catalysts where tungsten in addition to the catalytic ingredients of the invention was used, was using of nitrogen instead of steam, which is normally used in the known process is used to produce acrolein from propylene. A comparison with the catalyst of the invention shows that this known catalyst is a has the same selectivity, but only about half of the propylene is converted is compared with the catalyst of the invention.

II. Oxidation of acrolein to acrylic acid The effectiveness of the catalysts, which are made from a particular combination of metals becomes evident by the way the catalysts are made and whether they are a carrier contain or not or whether they are in pelletized form affects. the Porosity and the surface area of both the pellets and the support are important for the Effect of the catalyst is important and to some extent the amount of catalytic Affect material that is used on the carrier. When making the Catalytic converter, it is particularly important to ensure a uniform distribution of the various to achieve oxides contained therein; otherwise the effect one can get through the combination reached, lost. Molybdenum and the various catalyst or. Activator metals are added as their soluble salts, usually in acidic solution. she are sometimes mixed together in the same solution; but there possibly by premature precipitation, which is a non-uniformity in the finished catalyst would result Difficulties can arise are the metals mostly prepared in separate solutions, which in turn are controlled by the appropriate ones Conditions are mixed together. In general, the final pH is the Solutions somewhat on the acidic side, at around pH 6 to 6.5.

The solvent is then made from the solution of the catalyst components in the presence of a carrier so that the carrier is loaded if one is used is evaporated.

If a carrier is not used, the components are dried and pelletized.

The total amount of catalytic oxides applied to the support will be about 13 to about 30 weight percent based on the combined weight made of catalyst and carrier. A preferred load is about 18 to about 23 '. The preferred support is alumina and the surface area is preferred The carrier should not be more than 2 m2 / g with a porosity of 35 to 65 ', whereby 90, the pores range in diameter from 50 to 1500 microns.

The parameters for the feed composition, the flow rate, the temperature and pressure are well known. The aldehyde is generally in is present in the feed stream in an amount of 1 to 10 vol-96 with the remainder consists of molecular oxygen (0.8 to 21 vol-, ') and inert gas. Steam will often used as an inert gas, although air is normally used as the source of oxygen is used, nitrogen is also present as an inert gas component. The used Temperatures are in the range from 200 to 4000C and a pressure of 1 to 10 atm normally used. The contact times are usually on the order of magnitude from 0.4 to 15 seconds, depending on the temperature used and the effectiveness of the special catalyst.

The tantalum pentoxide used as a component is insoluble and difficult incorporate into the catalyst mixture. It will therefore generally be in solution the other components slurried. A particularly preferred method of manufacture the solution of the catalyst components consists in the fact that the tantalum pentoxide used as a colloid suspension. The commercially available oxide powder is first through a colloid mill before mixing with silica (if silica is used) and then to the remaining components, as in example 18 described, added. Using a finely divided colloid gives one better catalyst III. Oxidation of propylene to acrolein Example 1 Production of a catalyst in pellet form. Solution A is prepared by adding 344.6 Dissolve g of bismuth nitrate in 1200 ml of distilled water and then 75 ml of concentrated Adding nitric acid. 258.4 g of iron (III) nitrate are added to the resulting solution and 1014 g cobalt nitrate. Solution B is prepared by adding 1448 g of ammonium molybdate dissolves in 2750 ml of water with heating (about 900C) and stirring. After the ammol-umolybdate is dissolved, are added 2.18 g of potassium hydroxide. A thixotropic is formed Material by mixing solution A and B with stirring. Excess water will by heating (about 1000C) up to a 9.6 wt.% free water content (90.4, ' Solids) removed. The resulting catalyst material becomes cylindrical Pellets formed by slicing them into 0.95 cm (3/8 in.) Plastic sheets into the 0.64 in cm (1/4 in.) holes are drilled. The filled forms are in the oven (about 1500C) dried for 1 h and then the cylindrical catalyst pellets from the Mold pressed out with low air pressure. The pellets are then placed in an air oven 20th min calcined at about 2000C. After that, the furnace temperature will be approximately SOOC increments increased every 20 min until 5150C are reached. The temperature is then 4 h at 5150C held. This gives a catalyst with a surface area of 7.0 m2 / g, with 85 'of the pores ranging from 0.2 to 5 microns in diameter. The atomic ratio the metal elements in the catalyst composition is as follows: Mo15Co6,37Bi1 , 3Fe1, 35K0.071.

Example 2 Preparation of a supported catalyst Solution A is prepared by adding (1) 30.2 g of bismuth nitrate in 250 ml of distilled water, the 13 ml conc.

Contains nitric acid, dissolves, and in addition (2) 25.2 g iron (III) nitrate and adding 72.5 grams of cobalt nitrate. Solution A is preheated to 500 cc with stirring (1500C) aluminum oxide carrier with a surface area of <1 m2 / g added, whereby 9096 of the pores range from 50 to 420 microns in diameter.

The mixture is dried in a 150 ° C. oven for 1 hour. The solution B is prepared by adding (1) 148.4 g of ammonium molybdate (with heating and stirring) dissolves in 300 ml of distilled water. Keep stirring and heating until just one Turbidity occurs (after the cloud point, gelation occurs and the solution can not be used).

To prepare solution B, (2) prepare a second solution, by adding 2.09 g of the above potassium hydroxide solution to 50 ml of distilled water and 16.8 g of a 30% colloidal silica solution are added and (3) the solutions are added (1) and (2), prepared as above, mixed together.

Solution B then becomes the nitrate coated one (Solution A) Carrier added with stirring and then stirred on a steam bath until excess Water is removed. The carrier now impregnated with the catalyst salts is placed in an oven at 150 ° C until dry.

The catalyst is in an air oven for 20 min at 3000C, 20th Calcined at 4000 ° C. for 5 hours and at 425 ° C. for 5 hours and then removed and cooled. Man receives a catalyst with a surface area of 1.7 m2 / g. 90% of the pores lie in the range of 0.05 to 5 microns in diameter. The atomic ratio of the metals in the resulting catalyst is as follows: Mo15Co4.44Bi1.11Fe1.33K0.067Si1.49.

Example 3 A 100 ml volume of the catalyst pellets, 0.48 cm Diameter x 0.64 cm length (3/16 "x 1/4"), made as in Example 1 placed in a 2.54 cm stainless steel tubular reactor. The tube is heated to 3050C, and a gas mixture of 5.2% by volume of propylene, 60.8% by volume of air and 34% by volume of diluent (Nitrogen) is passed through the tube with a contact time of 2.6 seconds. at a propylene conversion of 93.5% with selectivities is obtained in a single pass to acrolein and acrylic acid of 86.4% and 5.7%, respectively.

Example 4 In a stainless steel tubular reactor with a jacket (diameter 1.59 cm) are added 260 ml of the carrier-containing prepared according to Example 2 Catalyst. The tube is heated to 3450C (a heat transfer medium is used in the jacket). A gas mixture of 5.2% by volume of propylene, 67.7% by volume of air and 26.7% by volume of nitrogen as dilution gas is passed through the tube with a contact time of 2.4 seconds. A propylene conversion of 86 'and one is obtained in a single pass Selectivity to acrolein of 94% and to acrylic acid of 3.0%.

E e g e 1 e 5 to 16 catalytic converters are operated in the same way, as described in Examples 1 and 2, using different atomic ratios, as in Example 3 (except for Example 15), prepared and as described in Example 4 examined. In Table I are the catalyst composition, temperatures and the contact times indicated at which the implementation will be carried out, and further are the resulting conversion of propylene and the selectivity to acrolein and Acrylic acid listed.

Table I Ex. Catalyst Composition Temp. Time Conversion Selectivity (%) No. Mo Co Fe Bi K Si (° C) (sec) (% C3H6) acrolein acrylic acid carbon oxides 5 15 4.6 1.35 1.3 0.07 1.3 310 2.6 86.4 92.9 0.13 6.97 6 15 5.2 1.35 1.3 0.07 - 315 2.5 93.0 88.7 7.01 4.29 7 15 6.4 1.35 1.3 0.07 - 310 1.6 90.5 92.2 5.4 1.1 8 15 7.0 1.35 1.3 0.07 - 300 2.7 93.4 92.0 5.1 2.9 9 15 4.6 1.35 1.3 0.07 - 295 2.3 92.9 91.0 3.7 5.3 10 15 4.6 1.35 1.66 0.07 - 300 2.7 79.8 91.1 4.7 4.2 11 15 4.6 1.73 1.3 0.07 - 340 2.5 78.8 91.2 5.0 3.8 12 15 7.0 2.03 1.96 0.11 - 315 2.7 87.6 93.1 3.6 3.3 13 15 5.7 1.66 1.6 0.09 - 300 2.7 92.5 91.4 4.8 3.8 14 15 5.0 1.0 1, 3 0.07 1.3 315 2.9 92.8 91.8 5.2 3.0 15 15 4.44 1.28 1.97 0.064 1.5 375 2.7 73+ 91 3.2 4.0 16 15 4.64 1.35 1.3 0.07 - 295 2.3 90 90 5.1 4.2 + This catalyst contains a carrier and was produced as described in Example 2 B. e i s p i e l 17 Similarly, isobutylene (IB) is passed through the catalyst composition of Example 7, Table I, with the preparation of methacrolein. The catalyst is in the form of 0.64 cm diameter x 0.64 cm long pellets with a surface of 8.7 m² / g, a porosity of 66%, with 83% of the pores between 0.1 and 3 microns. The olefin concentration in the feed is about 6.4 vol-96, Oxygen is in an amount of about 13-14 vol-96 and nitrogen is used as a diluent present in an amount of about 80 to 81 vol-96. For comparison, propylene is used passed over the same catalyst; the concentration in the feed stream is about 5.7 vol-, 'propylene, about 13 vol-,' oxygen and about 81 vol-, 'nitrogen as a diluent. The reaction temperature, the contact time and the obtained Results are shown in Table II.

Table II Olefin Temp. Time Convert. Selectivity (%) (° C) (sec) (%) + Aldehyde acid (CO & CO2 isobutylene 325 2.0 95.6 88.9 4.6 6.5 isobutylene 335 2.0 98.2 86.2 5.0 8.8 isobutylene 325 2.5 95.5 88.5 4.5 7.0 propylene 294 2.3 94.2 91.5 5.9 2.3 + Conversion is obtained in a single pass.

IV. Oxidation of acrolein to acrylic acid B e i 8 n i e l 18 Production of the catalyst A first solution is prepared by distilling 1400 ml Water to which 172.7 g of ammonium molybdate, 43.9 g of ammonium meta-vanadate and 6.0 g ammonium dichromate added, heated. A second solution is made, by adding 43.9 g of copper (II) nitrate to 75 ml of distilled water added, which was acidified with 3 ml of concentrated nitric acid. A third solution will be prepared by adding 27.5 g of tantalum pentoxide to 28.3 ml of the above colloid solution of silicon dioxide.

The second solution is added dropwise to the first solution while stirring and heating added. After the addition is complete, the third solution is added to the added to the other two with continued heating and stirring. The carrier, 0.64 cm beads of alumina, is preheated in an oven at 150 ° C and then to the above mixed solution with continued heating and stirring to remove given excess water. After most of the water has been removed, the carrier is placed in an oven at 1500C for 1 hour to dry. The dried one The catalyst is then calcined for about 6 1/2 hours.

The temperature will gradually increase from around 2000 to 4000C increased by 1 1/2 h. The temperature is then held at 4000C for the remainder of the time. The finished catalyst is removed and refrigerated before use. The same as above The catalyst prepared as described contains about 19.2% by weight of the metal oxides the catalyst support, and the atomic ratio of the metals is as follows: Mo15V5.7C40.73Cu2.76Ta1.89Si2.59 B e i s X i e l 19 In a manner similar to that described in Example 18, a Another catalyst is produced in which titanium is used instead of tantalum. After the first two solutions have been mixed as in Example 18, are 7.3 g of titanium dioxide was added to the mixed solution with heating and stirring. the remaining stages for production c; the catalyst is, as described above, carried out. The catalyst contains 19.2% by weight of metal oxides on the carrier and has the following atomic ratio of metals: Mo15V5.76Cr0.72Cu2.79Ti1 39.

EXAMPLE 20 Use of the catalyst The catalyst of Example 18 is placed in a stainless steel reactor made from a 2.54 cm Pipe with a length of 3.05 m within a concentric pipe, given that contains a heat exchange fluid for temperature control. The loading in the reactor contains 5.6 mol-96 acrolein, 30 mol-% nitrogen (as diluent gas) and oxygen, the oxygen to acrolein molar ratio being 1.48. the The temperature in the reactor is 3000C.

The contact time is 2.9 seconds. This feed stream is through passed the reactor over the above catalyst.

99% conversion of acrolein and selectivity are obtained to acrylic acid of 93.4%, with 4.4% going off for the carbon oxides. On similar ones Catalysts of different compositions are tested. The mole% Acrolein in the feed in each of the following examples is in Range from about 4.5 to about 5.5%. The results are shown in Table III. Tabel III Ex. Catalyst Components Reactor- Contact Conversion. Selectivity (%) No. Mo V Cr Cu Ta Nb Si temp. (° C) time (sec) (% Acrn.) Acrylic acid carbon oxides 21 15 6.67 0.93 3.22 2.2 - 2.92 280 3.5 95 89 9.6 22 15 5.7 0.72 2.76 1.89 - - 289 2.5 95.1 94.8 5.2 23 15 5.7 0.72 2.76 1.89 - 2.59 300 2.9 99.5 93.0 6.0 24 15 5.7 1.09 2.76 1.89 - - 301 2.2 89.8 91.2 8.8 25 15 5.71 0.74 2.76 - 1.78 4.2 283 3.7 96.0 88 9.5 26+ 15 5.47 0.71 2.64 1.82 - 2.9 276 3.2 98 91 9.0 27 15 7.48 1.51 2.75 - 1.14 - 280 3.1 89.4 88.1 10.2 28 ++ 15 5.75 0.73 2.78 1.89 - - 289 2.2 94.9 96.3 3.7 + Only 2.6 mole percent acrolein is used in the feed stream ++ The catalyst is made using a colloid form of tantalum B. e i 5 n i e 1 29 In the same manner as in Example 19, other catalysts are used which contain different amounts of titanium. As in Example 20 is described, tested and the results are shown in Table IV.

All components are the same as those in Example 19 with the exception of titanium, the atomic ratio of which is listed in the column with the heading (x) will.

Table IV Catalyst Reactor Contact Conversion Selectivity (%) sator (x) temp. (° C) time (sec) 96Acrn. Acrylic carbon acid oxides A 0.99 291 3.43 87.7 94.0 5.9 B 1.19 291 3.45 94.6 93.8 6.2 c 1.39 290 3.57 99.2 95.2 5.4 D 1.46 280 3.59 98.5 95.0 5.0 E 1.85 291 2.62 98.7 94.2 5.8 F 2.18 294 3.51 97.3 93.8 6.2 G. 3.0 291 3.3 98.4 92.2 6.9 Example 30 In a preferred manufacture of the Catalyst, a first solution is prepared by adding 6000 ml of distilled Water, to which 1427.6 g of ammonium molybdate, 362.8 g of ammonium meta-vanadate and 49.0 g ammonium dichromate added, heated. A second solution is made, by adding 363 g of copper (II) nitrate to 150 ml of distilled water containing 20 ml conc. Nitric acid has been acidified. A third solution is made, by adding 226.4 g of colloidal tantalum pentoxide with a size below 1 micron to 500 add ml of water.

The second solution is added dropwise with stirring and heating given the first solution. After this addition is complete, the third solution to the other two added with continued heating and stirring. The carrier, 0.64 cm spheres of alumina, is preheated in an oven at 1500C and then to the above mixed solution with further heating and stirring for removal excess water added. After most of the water is removed, the support is placed in an oven at 150 ° C. for 1 hour to dry. The dried one The catalyst is then calcined for a period of about 6 1/2 hours, the Temperature gradually increased from about 200 to 4000C over the course of about 1 1/2 hours will. The temperature is kept at 4000C for the rest of the time. The finished Catalyst is removed and cooled before use. The one as described above The catalyst produced contains about 22.3 total, 'metal oxides on a catalyst support. The atomic ratio of the metals is as follows: Mo15V5.75Cr0.73Cu2.78Ta1.9.

Will the above catalyst for the oxidation of acrolein be the same As used in Example 20, a 99.896 conversion of Acrolein and a selectivity of 96.5% to acrylic acid.

B e i 8 p i e l 31 A catalyst for the oxidation of propylene to acrolein becomes together with a catalyst for the oxidation of acrolein to Acrylic acid used in sequential operation in the following ways.

A metal oxide composition, the atom-to-metal ratios of Mo15Co6.7Fe1.35Bi1,3'011 possesses and in the form of pellets with a diameter of 0.64 cm and a thickness of 0.64 cm is present, is in a first column, namely a stainless steel tube reactor, 3.66 m long and 3.2 cm in diameter. A pipe connects these first column with a second column (5.8 m long x 3.81 cm inner diameter) the same stainless steel in which the carrier containing catalyst is put into of example 30 has given. Each column is filled with a heat exchange fluid that is passed through an outer, concentric tube flows, heated. You lead into the first pillar a gas stream containing 5.3 mol% propylene, 9.4 mol% oxygen and the remainder nitrogen contains, at a pressure of 2.13 atmospheres and and a flow rate of 5.67 kg / h. A contact time of 2.19 seconds is obtained. The feed material is poured onto a Temperature of 325 ° C and the first reaction column is kept at 331 0C. The exiting stream is passed through the pipe to the second column, which is at 279 ° C is maintained. The contact time in the second column is 4.87 seconds gases emerging from the second column are quenched and the non-condensable Gases are recycled to the first column. The conversion of the propylene is 98.3% and the yield of acrylic acid is 8 g.

Claims (10)

Claims 1. Catalyst for the oxidation of low olefins, which contain 3 to 6 carbon atoms, to the analogous, unsaturated aldehydes, characterized in that it contains the oxides of cobalt, iron, bismuth, molybdenum and of an alkali metal, the atomic ratios of the metals in the range of Co4 4 7.0Fe1-2Bi1-2Mo152, 05-0.2 lie. 2. Catalyst according to claim 1, characterized in that in addition Silicon is present in an atomic ratio ranging from 0.5 to 3.0. 3. Process for the preparation of an unsupported oxidation catalyst in pellet form containing the oxides of cobalt, iron, bismuth, molybdenum and an alkali metal contains, characterized in that (1) a first solution of compounds of cobalt, iron and bismuth, (2) a second solution of the compounds from molybdenum and the alkali metal, (3) the first and second solutions mixed, (4) most of the water removed from the solution, (5) pellets out of the solution forms, (6) dries the pellets, (7) the dried pellets in air calcined for a time of 4 to 8 hours, the calcining temperature gradually increasing from 2000 to 5000C during the first stage and the temperature is held at about 500 to 5300C for the remainder of the time, and (8) the calcined Pellets cools down. 4. The method according to claim 3, characterized in that the catalyst additionally contains a silicon oxide and that the silicon as a solution of a compound of silicon is added to the second solution before the second solution to the first solution is given. 5. A catalyst containing a carrier which is used for the oxidation of Acrolein is suitable for acrylic acid, characterized in that it contains the oxides of Molybdenum, vanadium, chromium, copper and at least one oxide of tantalum, and titanium Contains niobium on an inert carrier, the atomic ratios of the metals Mo15V5-10Cr0.2-2Cu2-5M0.1-3 be, where M is tantalum, titanium, niobium or their mixtures. 6. Catalyst according to claim 5, characterized in that it additionally Silicon as its oxide contains 1 to 5 atoms of silicon. 7. Process for the oxidation of an olefin to the unsaturated aldehyde in the vapor phase, characterized in that a gas mixture from the olefin and oxygen together with an inert diluent at a suitable temperature and contact time passes over a catalyst that removes the oxides of cobalt, iron, Contains bismuth, molybdenum, potassium and optionally silicon, the metals in atomic ratios of Co4.4-7.0 Fe1-2Bi1-2Mo15K0.05-0.2 and, if present, Si11.5 available. 8. The method according to claim 7, characterized in that the inert Diluent is recycle gas that essentially nitrogen, Contains or consists of carbon oxides, oxygen and argon. 9. Process for the oxidation of acrolein in the vapor phase with manufacture of acrylic acid using a catalyst containing a carrier, characterized in that a catalyst is used which contains the oxides of metals contains, the metals in the atomic ratio of Mo15V5-10Cr0.2-2Cu2-5M0.1-3 are present, in which M is a metal selected from the group consisting of tantalum, titanium, niobium or theirs Means mixtures. 10. Two-stage process for the oxidation of propylene to acrylic acid, characterized in that (A) a gaseous mixture of propylene and oxygen together with an inert diluent at a suitable temperature and contact time passes over a catalyst that removes the oxides of cobalt, iron, bismuth, molybdenum, Contains potassium and silicon, the metals in atomic ratios of Co4.4-7.0Fe1-2Bi1-2Mo15K0.05-0.2 and, if present, Si1-1.5 are present, and (B) the effluent from (A) via a a carrier containing catalyst conducts the oxides of metals in atomic proportions of Mo1 contains 5V510Cr0.22Cu25M0.13, in which M is selected from tantalum, titanium, Niobium and their mixtures.