NL7906480A - CATALYSTS AND METHODS USING THEM - Google Patents

Description

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HALCON RESEARCH AND DEVELOPMENT CORP., In New York, New York,

Far. St. v. America.

Catalysts and Methods Using These.

The invention relates to catalysts, in particular catalysts for the vapor phase oxidation with molecular oxygen of isobutene and / or tertiary butyl alcohol to form methacrolein and to a method for using such catalysts.

It is known that unsaturated aldehydes, such as acrolein and methacrolein, can be prepared by the vapor phase oxidation of the corresponding olefins by molecular oxygen in the presence of a suitable oxidation catalyst. A variety of catalyst compositions have already been proposed for this purpose, and many of them consist of the oxides of molybdenum, iron and especially bismuth. Generally, the selectivity to the desired aldehyde, ie, the molar amount of aldehyde obtained per mole of olefin converted, is relatively low when using the catalyst compositions of this type. Recently, attempts have been made to increase the selectivity of the reaction by including oxides of more unusual elements in the catalyst.

U.S. Patent 4,087,382 discloses an improved catalyst containing the elements molybdenum, bismuth, iron, cobalt, thallium, antimony and optionally silicon.

Such catalysts have been found to have improved performance over the previously known catalysts. However, further improvement has been sought since when such catalysts are to operate at pressures above atmospheric, which is typical of engineering practice, inferior results are obtained compared to the behavior at atmospheric pressure. Recovering the lost behavior at pressures above atmospheric was desired for a technically viable catalyst. In addition, an improvement in long-term stability of the catalyst was desired.

The invention now provides an improved catalyst of such a composition as that of U.S. Pat. No. 4,087,382, but with additional elements which have been found to improve performance as will be apparent from the discussion below.

The literature relating to catalysts for use in the oxidation of lower olefins to unsaturated aldehydes is difficult to oversee due to the large number of elements which have been found to be useful to various investigators. With regard to the catalyst composition disclosed below, the following patents are believed to be particularly material.

US Pat. No. 4,034,008 discloses a catalyst, which is potassium-free and contains molybdenum, bismuth, iron, cobalt and / or nickel, antimony and / or ruthenium and optionally a trace chloride. The patented catalyst does not include thallium, the rare earth metals, the alkali metals, the alkaline earth metals or tungsten. Although broadly disclosed for oxidation of α, β-unsaturated monoalkenes to the corresponding aldehydes or carboxylic acids or for ammoxidation of the same olefins to the corresponding nitriles, the examples are only about the oxidation of propylene to acrolein. It may be noted that although propylene and isobutylene are chemically related, the oxidation of isobutylene (or its equivalent, tertiary butyl alcohol) is considered to be the most difficult reaction to perform. Although o

It is stated that the catalysts are calcined at 400-550 ° C

for 2-24 hours, the examples show that the catalysts are calcined at temperatures in the range 450-490 ° C. It is also stated that the catalysts are preferably used on a support such as silicon oxide, aluminum oxide, silicon carbide, zirconium oxide, and titanium oxide.

The importance of the use of thallium is indicated in U.S. Patent 3,951,861, which shows that the thallium content is critical with respect to a catalyst composition of molybdenum, bismuth, iron, cobalt and / or magnesium and / or manganese, along with nickel and optionally phosphorus and a group of other metals, specifically copper, calcium, strontium, zinc, cadmium, tin and lead.

This catalyst contains no antimony, the alkali metals or the rare earth metals. The patent is specifically directed to the oxidation of propene to acrolein, although a related patent, U.S. Patent 5 3,928,462, discloses the advantages of small amounts of thallium in such a catalyst used for the oxidation of isobutylene to methacroline. The catalysts are generally calcined at temperatures of 525-550 ° C. Preferably they are used on a support such as silicon oxide, aluminum oxide, silicon carbide and titanium oxide.

Nickel is used in a number of catalysts, particularly in the aforementioned U.S. Pat. Nos. 4,034,008 and 3,951,861. U.S. Pat. No. 3,454,630 emphasizes the benefits of nickel and / or cobalt oxides. In this patent, nickel and cobalt are considered equivalents and it is suggested that one or the other may be used. The catalyst of this patent lacks the thallium, antimony, silicon and alkali metals of the present catalyst and requires the presence of phosphorus.

Example XLI from this patent shows relatively poor catalyst behavior with regard to selectivity to methacrolein.

Silicon is also referred to as a useful component of such catalysts as disclosed in U.S. Pat. No. 4,034,008 and U.S. Pat. Nos. 3,186,955 and 3,855,308. The catalyst of U.S. Pat. No. 3,186,955 preferably contains barium and more bismuth than molybdenum and lacks the iron, cobalt, thallium, antimony, nickel and alkali metals of the present catalyst. The catalyst is disclosed for multiple purposes, including the oxidation of isobutene to methacrolein. Calcination above about 565 ° C is indicated to be detrimental to the catalyst behavior. The catalyst of U.S. Pat. No. 3,855,308 lacks antimony and nickel, but requires tungsten and is said to be calcined at a temperature between 350-600 ° C, although a temperature of 450 ° C is generally used in the examples .

British Patent 1,456,752 claims a catalyst consisting essentially of molybdenum, bismuth, cobalt, and iron and improved by the addition of antimony. It is stated, 7906480 Λ 4, that antimony has the effect of improving the selectivity of methacrolein / but decreasing the activity of the catalyst when calcined at temperatures in the range of 500-550 ° C. In that case, add at least one element from a large group of 5 elements, including barium and nickel, to restore the activity lost by the addition of antimony. It is further stated that when a catalyst is calcined between 600-700 ° C, an improved activity is obtained. An alkali metal and / or thallium would be added to such catalysts. In the examples, the catalysts 10 are generally mixed with silicon carbide powder as a carrier. The patent states that the. pressure is not critical at. The reaction.

The patent contains no information regarding the specific surface area or pore diameter of the disclosed catalyst. Silicon oxide is not included as an ingredient of the catalyst.

In general, it is believed that the composition of a catalyst of this type cannot be predicted by combining the many elements disclosed in the prior art, but that the catalyst behavior should be determined experimentally at the expected operating conditions. . As a result, small changes in composition can be very important in obtaining improved catalyst performance and in particular in optimizing the catalyst composition to be suitable for a specific reaction and set operating conditions.

As will be shown in the description of the invention that follows, changes in operating conditions and in methods of preparation can lead to a deterioration of catalyst behavior and necessity of adding ingredients to a catalyst to restore the loss in behavior.

It has been found that the conversion of isobutene and / or tertiary butyl alcohol with high selectivity to methacrolein can be carried out by molecular oxidation in the vapor phase in the presence of a catalyst composition consisting essentially of the oxides of molybdenum, cobalt, iron, bismuth, thallium, antimony, silicon, nickel and one or more members of the group consisting of alkali metals, the alkaline earth metals, the rare earth metals, including lanthanum, tungsten and 7906480 9 * 5 mixtures thereof.

The catalyst composition of the invention can be expressed by the following general formula: 5 Mo Co, Fe Bi _T1 Sb_Si NLX.O.

abcdefghij wherein X is at least one member of the group consisting of alkali metals, alkaline earth metals, rare earth metals, including lanthaaQ, tungsten and mixtures thereof, and where aj represents the atomic ratio of each 10 component so that a = 12, b = 0.2 -8, c = 0.05-5, d »0.2-4, e = 0.1-5, f = 0.01-5, g = 1-20, and h = 0.05-5, i has a positive value of up to 4, and j has a value determined by the valency and amounts of other elements in the catalyst.

More particularly, a preferred catalyst composition according to the invention consists of the oxides of the specified elements in the following atomic ratio: Mo = 12, Co = 4, Fe = 3,

Bi = 1, T1 = 0.5, Sb = 0.3, Si * 6.6, Ni = 2, Cs = 0.3 and K = 0.3 based on the composition of the original solutions. The catalyst composition can be considered either as a mixture of oxides of the said elements or as oxygen-containing compounds of the elements and the use of the term "mixtures of oxides" is to be understood to include either or both forms. As prepared and / or under the reaction conditions, the catalyst can be in any form or both.

The catalyst is prepared according to methods generally known in the art, but is calcined at higher temperatures than those generally used heretofore, namely at least about 525 ° C and preferably above 550 ° C . After calcination for a sufficiently long time, the catalysts of the invention will have a BET specific surface area in the range of 0.5-10 m / g, preferably 2-6 m / g, and will not exceed about 10% of the pore volume, preferably about 3%, have pores smaller than about 100.10 µm.

In another aspect, the invention includes a process for the vapor phase oxidation of isobutene and / or tertiary butyl alcohol to form methacrolein in the presence of the above-described catalyst.

Description of the Preferred Embodiments.

5 Catalyst composition and preparation.

The catalyst according to the invention essentially consists of the oxides of molybdenum, cobalt, iron, bismuth, thallium, antimony, silicon, nickel and one or more members of the groups consisting of the alkali metals, the alkaline earth metals, the rare earth metals, including lanthanum , tungsten and mixtures thereof and has the following general formula:

Mo Co, Fe Bi Tl Sb_Si Ni X.O. abcdefghi] 15 wherein X is at least one member of the group consisting of the alkali metals, the alkaline earth metals, the rare earth metals, lanthanum, tungsten and mixtures thereof, and where aj denotes the atomic ratio of each component, so that when a = 12, b = 0, 6-8, c = 0.05-5, d = 0.6-4, e = CVOL — 5, f - 0.01-5, g = 1-20, h = 0.05-5, i a has a positive value up to 20 times 4, and j has a value determined by the valency and amounts of the other elements in the catalyst.

The catalyst composition is calcined at a temperature of at least 525 ° C long enough to reduce the BET specific surface area to 0.5-10 m / g catalyst. Preferably, the BET specific surface will be between about 2-6 m / g of catalyst and no more than about 3% of the surface will come from pores with a diameter of less than 100.10 µm. The BET specific surface is measured with the nitrogen adsorption method described in Brunauer, Emmett and Teller in "Journal of the American Chemical Society", 30 Vol. 60, 309 (1938). The pore diameter and volume are determined by the critical porosimeter method described in "The Analytical Edition of Industrial Engineering Chemistry", Vol. 17, page 787 (1945). The specific surface area, pore size and pore volume are often related by the equation mentioned in "The Analytical Edition of 35 Industrial Engineering Chemistry", Vol. 13, p. 28 (1941).

7 9 0 6 4 8 0 r * 7

The catalyst composition is preferably used in the form of pills or other such compressed shapes of various sizes. The composition can be formed in a conventional manner using techniques well known to those skilled in the art. For example, compounds of molybdenum, cobalt, iron, thallium, antimony, bismuth, cesium, potassium, and nickel can each be dissolved in a small amount of water or other solvent, and then combine the solutions with colloidal silica and evaporate the mixture to dryness.

To prepare the catalyst, the various components can be dissolved in the form of different salts or other compounds of suitable type, and no specific form is required for the catalyst precursors. However, the use of ammonium salts, halides, for example chlorides, nitrates or acid forms of the elements to be supplied, are particularly suitable. Preferably, however, aqueous solutions and water-soluble forms of the elements, except the silica portion of the catalyst, which is usually insoluble, are used. In some cases, acids and / or bases can be added to the solutions to facilitate dissolution of the catalyst precursor. For example, if desired, acids such as hydrochloric acid or nitric acid or bases such as ammonium hydroxide can be used. Silicon can be added in the form of an aqueous colloidal solution of SiO4. Typical suspensions of colloidal filamentous oxide particles in water or alcohol are available from Nalco Chemical Company (Nalcoag brand) and E.I. DuPont de Nemours (Ludox brand). Colloidal silicon oxide is also available in powder form from Degussa (Aerosil brand). The particles can range from - 10 2 600.10 m in size, which have a BET specific surface area of 50 m / g to particles of 40.10 m, which have a BET specific surface area of 250 m2 / g.

The powder resulting from evaporation is thoroughly dried and preferably sieved to remove large particles that would hinder the formation of uniformly compressed shapes, such as pills. The powder is typically screened through a 0.833 mm mesh screen. The powder is mixed for a long time with an organic binder of any conventional type, such as polyvinyl alcohol, and the mixture is thoroughly dried and sieved again, typically into particles of size 0.175-0.833 mm.

7906480 * 1 8

Preferably, the dried particles are then combined with a lubricant, again of any conventional type, such as stearic acid or graphite, and pressed into the desired shape, e.g., pellets, or extruded or otherwise molded, which compressed shapes typically have heights and diameters of 1 , 6-9.5 mm. Finally, the catalyst composition thus produced is activated at a higher temperature than has generally been used in the catalyst art and for a longer duration as required to obtain the desired BET specific surface area. For example, the pills are typically placed in an oven or in a tube through which air is passed at an elevated temperature (eg, at least 525 ° C, preferably above 550 ° C) for 2-10 hours. According to a particularly preferred activation step, the temperature is allowed to rise at a rate of from 20 ° C per hour to 600 ° C and maintains this temperature for 3 hours.

It will be understood that the foregoing description regarding the preparation of the catalyst in a form suitable for use in the vapor phase oxidation reaction is merely illustrative of many possible preparative methods and is given by way of example only, with the exception of the calcination portion of the preparation procedure, which is an important aspect of the invention. However, this method is particularly suitable and preferred.

Use of the catalyst.

The catalyst and methods of the invention are useful in general for the production of unsaturated aldehydes by oxidation with molecular oxygen of lower olefins and the ammoxidation of olefins. The preferred starting materials are the monophenically unsaturated olefins having 3 or 4 carbon atoms or mixtures of olefins. As noted previously, the catalysts have been specifically developed for optimal performance under particular starting materials and processing conditions. Thus, the catalyst disclosed and claimed herein is particularly suitable for the oxidation of isobutylene and / or tertiary butyl alcohol to methacrolein.

When the catalyst according to the invention is used in the vapor phase oxidation of isobutene and / or tertiary butylalko 79 ft 6 4 8 0 8 ft.

hollow to form methacrolein, the processing conditions used generally are those associated with this reaction. The reaction in which the catalyst compositions of the invention are of particular utility and providing high selectivity involves contacting isobutene and / or tertiary butyl alcohol in the vapor phase with the catalyst and molecular oxygen, preferably also in the presence of steam. Once the reaction has started, it is self-entertaining because of its exothermic nature. A variety of reactors have been found to be useful, and the common multiple tube heat exchange type, with the catalyst pellets located within the tubes, is sufficient. The process can be performed in conventional equipment commonly used for reactions of this type.

The gaseous feed to the reactor contains relatively low concentrations of olefin, oxygen and steam. Typically, an inert gas such as nitrogen is also present. The oxygen is usually added as such or as air or as oxygen-enriched air.

As mentioned, conventional oxidation conditions can be used but for best results, the olefin is generally present in concentrations of about 2-20% by volume of the total feed, preferably 5-15% by volume, and the corresponding ranges for oxygen are 4-30 vol.% (Limited by the flammability range of mixtures) and preferably 10-20 vol.% And for steam up to 30 vol.%, Preferably 5-25 vol.%, The remainder being inert gas or gases.

The temperature of the reaction should be within the range of 250-500 ° C, preferably 300-400 ° C for best results, and the optimum temperature is 310-370 ° C. Since the reaction is exothermic, heat transfer means are commonly used, such as by surrounding the tubes containing the catalyst pellets, with a salt bath or with boiling water.

The pressure in the reactor has an effect on the catalyst behavior, as will be seen later. Although the reaction can be carried out at atmospheric, superatmospheric or subatmospheric pressure, pressures ranging from atmospheric pressure to a maximum of 1470 kPa, preferably 784 kPa and most preferably 617 kPa are preferably used. Typically, a pressure of 333 kPa is used.

7906480 9

The methacrolein product can be recovered by various methods known to those skilled in the art. For example, the methacrolein can be condensed or washed with water or other suitable solvents, followed by separation of the unsaturated aldehyde product from the washing liquid. The gases remaining after the methacrolein removal step can be recycled to the reaction if desired, and in such a case, the net CO produced by reaction can be removed by conventional means, such as absorption in an aqueous carbonate solution, or blowdown from the system.

The invention will now be illustrated by the following examples, which are for illustrative purposes only and should not be construed as limiting the invention.

Example I

15 Known state of the art.

636 g of the molybdenum salt (NH.), .Mu. 4H.0 op. 262 g of Co (NO.) Are then dissolved. 6H 2 O 40/24 2 322 in 300 ml of water, 60.6 g of Fe (NO 2) 3. 9H 2 O in 200 ml water, 79.8 g Tl NO 3 in 400 ml water, 68.4 g Sb Cl 2 in a mixture of 100 ml water and 30 ml concentrated hydrochloric acid and 275 g Bi (NO). 5HO in a mixture of 200 ml of water and 50 ml of concentrated nitric acid. Sufficient ammonium hydroxide is added to bring the pH of the solution to a value of 7. These solutions are fed to a rotary dryer with a capacity of 4000 ml and the mixture is evaporated to dryness in the dryer and the temperature is allowed to rise to 300 ° C. The resulting powder is removed from the dryer and dried in an oven at 400 ° C for 12 hours. The dried powder is sieved through a sieve with a mesh size of 0.833 mm, a 4% aqueous solution of polyvinyl alcohol is added in an amount sufficient to obtain a moist mixture and the mixture is dried at 75-80 ° C, until it is 30 ° C. moisture content reaches 2-4%. The dried mixture is then screened to a size of 0.251-0.833 mm and about 2% stearic acid powder is mixed thoroughly. Pills of the resulting mixture having a height and diameter of 4.8 mm are then formed. The pills are then activated in an oven by gradually heating it at a rate of 0 o 20 C per hour to about 380 C and holding at this temperature for 7906480 & 3 10 16 hours. The activated pills have a density of 0.95 g per cm and a specific surface area of 6.5 m / g. The catalyst components molybdenum, cobalt, iron, thallium, antimony and bismuth, based on the amounts in the original solutions, have atomic ratios of 12.5, 0.5, 1.1, 1.5 respectively.

50 ml of this catalyst composition is charged to a reactor consisting of a 1.25 cm stainless steel pipe, 2.7 m long, which is filled with 300 ml of inert filler (silicon carbide) below the catalyst bed and sufficient inert filler above the catalyst bed. fill the reactor. Nitrogen-diluted mixtures containing 9% by volume of isobutene, 10% by volume of oxygen and 20% by volume of steam are fed to the reactor at a pressure of about 1 atmosphere at temperatures of 360-370 ° C and a space velocity of about 3000 hours. The term "space velocity" is used here in the conventional sense and means liters of gas at standard temperature and pressure per liter of catalyst per hour. The reaction is run with continuous supply of feed and continuous extraction of exhaust gas. The exhaust gas is analyzed by gas chromatography at several hour intervals except for the measurement of CO / CC> 2 by infrared absorption using conventional methods.

The combined production of methacrolein and methacrylic acid is reported as both products are useful and generally the methacrolein can be separated and oxidized in a separate reactor to form additional methacrylic acid, typically for conversion to methyl methacrylate. The predominant product is meth-acrolein and the amount of methacrylic acid present is only about 2-3% of the total, shown in Table A: 7906480 s 11

T & BEL A

Selectivity,%

Methacrolein Acetic Acid CO +

Test Duration in Isobutene- + methacryl- CO ^ 5 no. Hour conversion% acid __ 1 12 55.0 86.9 2.4 4.7 2 62 54.0 88.5 1.7 4.8 3 172 61, 8 86.8 1.54 4.34 4 177 60.0 87.8 1.76 3.70 10 5 180 59.2 87.4 1.9 3.80 6 210 61.6 86.0 1.51 4.80 7 214 65.3 87.4 1.35 3.91 8 231 67.3 88.8 1.85 2.47 9 235 59.1 87.5 1.65 3.32 15 10 238 58, 6 87.4 1.42 3.65 11 255 60.7 87.6 1.48 3.71 12 261 57.6 87.2 1.60 3.63 13 279 63.4 86.5 1.89 3 .78 14 285 57.1 85.0 2.05 4.11 20 15 306 57.2 86.9 1.80 3.59 16 308 63.2 85.1 1.86 4.08

Example II

A catalyst with the same composition as in Example 1 and a specific surface area of 5.6 m / g is tested.

2

The reactor pressure increases to 3.46 kg / cm absolute, leading to a decrease in conversion and selectivity to methacrolein as shown in Table B. The feed gas space velocity is 3000 hours * and the gas composition is substantially same as in Example 1, but now 8.5% by volume of tertiary butyl alcohol (TBA) supplied for the isobutene feed used in Example 1, with the result that after dehydration the gas composition is 7% by volume of isobutene, 9 , 8% by volume of oxygen and 20% by volume of steam, the balance being nitrogen. The temperature is between 335-340 ° C.

35 From a comparison of Tables A and B

7906480 -r- * 12 it can be seen that an increase in reaction pressure leads to an inferior behavior, as indicated by the poorer selectivity for the desired product methacrolein and the increase in by-product acetic acid and CO / CO2. Since the conversion is lower in this example, the selectivity would be expected to be higher than that of Table A had the increased pressure had no effect. This inferior behavior at higher pressure was found even though the catalyst of Table B has not been used as long as that of Table A, which may have suffered some loss in behavior over time. It can be concluded that the oxidation of isobutene and / or tertiary butyl alcohol (they are considered equivalent starting materials) to methacrolein is sensitive to increase in pressure in this relatively low range. It should be noted that one would normally use a pressure above atmospheric and that the 340 kPa pressure used in Example II is a more realistic value for industrial applications.

7906480 13

TABLE · B

Selectivity /% Methacrolein Vinegar- CO +

Test Duration in TBA + methacrylic acid CO2 5 No Hour Conversion% Acid 17 38 46 76.5 6.1 13.2 18 54 51 75.8 5.2 13.3 19 56 50 76.5 5.4 12 .3 20 58 46 77.4 5.0 11.4 10 21 60 47 78.3 4.7 10.8 22 66 43 77.5 4.4 12.3 23 68 46 78.3 4.7 11, 1 24 80 60 79.3 5.0 9.8 25 82 60 77.3 5.5 10.9 15 26 86 50 78.9 4.4 11.0 27 82 45 79.7 4.4 10.6 28 96 60 76.3 5.2 13.1 29 100 61 76.9 6.1 12.1 30 104 61 77.7 5.6 11.7 20 31 108 57 79.1 5.5 10.5 32 118 51 79.4 5.0 10.4 33 122 52 80.5 4.4 10.0 34 126 51 79.2 4.9 10.6 35 130 50 78.8 4.8 11.1 25

Example III

Example II is repeated, but now O 0 is heated

in the preparation of the catalyst to about 600 ° C instead of 380 ° C

2 in example II. The specific surface area of the catalyst is found to be 2.4 m / 5P g. The feed gas composition is 5.7 vol.% TBA, 9.8 vol.% Oxygen, 20% steam and the balance nitrogen. It appears that a temperature of 435-445 ° C is required to obtain a conversion of 33-36% and a selectivity to methacrolein + methacrylic acid of about 75.5%.

The CO + CO2 selectivity appears to be about 20%. Thus, heating the 55 catalyst to a temperature of 600 ° C instead of 380 ° C of Example 790 results in a significant deterioration in the catalyst behavior.

Example IV

3 636 g of the molybdenum salt are dissolved in 750 cm of water. 4Η ^ 0. Furthermore, 349 g of Co (NO2) 2 are dissolved. 6H 2 O in 400 ml of water, 336 g Fe (NO 2). . 9HJ5 in 400 cm 3 water, 175 g 3 J J 1 3

Ni (NO1). 6H_0 in 300 cm water, 40 g Tl NO in 400 cm water, 3 2. έ 2 3 17.4 g CsNO, in 100 cm water, 6 g KOH in 50 cm water, 20.4 g J 3 3 10 SbCl in 30 cm water and 10 cm concentrated hydrochloric acid and 145 g 3 3 3

Bi (NO ^) 2. 5H20 in 100 cm water and 25 cm concentrated nitric acid.

To all the above solutions mixed together, 300 g of 40% colloidal silicon dioxide (Ludox HS 40%, from DuPont de Nemours and with an average particle size of 120.10 m and a BET specific surface area of 232 m / g) are added. Sufficient ammonium hydroxide is added to bring the pH of the solution to a value of 7. The solution is then evaporated to dryness and made into pellets in the manner described in Example I, but now the pellets are activated by heating in air at a rate of 20 ° C per hour to about 340 ° C and then quickly to 600 ° C C and held at that temperature for 2.5 hours. The final catalyst has atomic ratios of molybdenum, cobalt, iron, bismuth, thallium, antimony, silicon, nickel, cesium and potassium of 12, 4, 3, 1, 0.5, 0.3, 6.6, 2.0, 3 and 0.3, respectively, based on the composition of the original solutions. During activation, the specific surface area decreases from about 23 m / g to 5.1 m / g.

The catalyst is tested under the conditions of Example III, but now only a temperature of about 335 ° C is required to obtain the superior results shown in Table C. The catalyst is superior to the results of Example II and also of Example I, which is carried out at the more favorable pressure of 1 atmosphere.

7906480 'r. v 15

TABLE C

Selectivity /% Methacrolein Vinegar- CO +

Test Duration in TBA + methacrylic acid CO2 5 no, hour conversion,% acid 36 12 67 84.7 2.4 6.3 37 18 70 83.9 2.3 7.5 38 22 70 84.2 2.2 7 , 1 39 26 72 84.2 3.3 5.0 10 40 34 70 84.9 2.2 6.6 41 38 70 85.2 2.4 6.4 42 60 71 83.8 2.7 6, 2 43 100 68 84.2 2.1 7.6 44 2000 68 84.4 2.4 6.5 15

It has been found that the catalyst of Example I with added nickel, silica, cesium and potassium has superior performance compared to the catalyst of Example I used so far, but under more rigorous conditions of Example III.

20

Example V

Such results are shown in the following Table D, in which a catalyst of the same composition as in Example IV is prepared, but now the silicon content is increased from an atomic content of 6.6 to 12. The specific surface area of the catalyst 2 O

tor decreases from about 23 m / g to 7.8 m / g by heating to 600 ° C

during the preparation of the catalyst. In contrast to the previous examples, the feed composition, pressure and space velocity are varied during the test run.

7906480 16 <*> +

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7906480

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Example VI

The effect of nickel on the catalyst of the invention is shown in the following Table E, in which the catalyst composition of Example IV, excluding the nickel content, is tested under the same conditions as in Example IV.

TABLE E

Selectivity,%

Trial Duration Temp. TBA Methacrolein Vinegar- CO + 10 no. In hours ° C conversion + methacrylic acid CC> 2% acid _; _ I__ 60 9 368 65 82.5 3.1 9 61 11 368 66 83.3 3.3 8 62 13 366 64 83.6 2.9 8.9 15 63 19 372 68 80.9 3.2 11

Comparing Tables C and E, it appears that the conversion of tertiary butyl alcohol is lower when the catalyst lacks nickel, as evidenced both directly by measurement and indirectly by the temperature required for the reaction. The specific surface area of the catalyst is 4.8 m / g.

Example VII

A catalyst according to example IV is prepared, but.

Now potassium and cesium are replaced by calcium and 52.8 g 3 are dissolved

Ca (C2H.jO2). H2O in 200 cm of water and add to the solution to provide calcium in a catalyst of the following composition (based on the original solutions): 30 Mo12Co4Pe3Bi1Tl0i5Sb6i6Ni2Ca1Oj o

The catalyst is heated to about 600 ° C for 3 hours during the calcination, which causes the specific surface area to decrease from about 20 m / g to 5 m / g. The catalyst is tested with a feed composition of 7 vol.% Isobutene, 15 vol.% Steam, 16 vol.% Oxygen 7906480 2 18 and the remainder nitrogen and a pressure of 2.44 kg / cm absolute and a space speed of approximately 2250 hours 1 with the following results:

TABLE F

5 Selectivity,%

Test Duration Tempe- iC ^ Methacrolein Vinegar- CO + no. In hour rature turnover- + methacrylic acid CO2 _ ° C ting,% _acid ____ 64 9 345 66 78.2 3.7 10.7 10 65 33 371 75 80 , 8 3.7 10.6 66 42 379 84 79.7 5.2 11.2 67 63 379 87 80.7 3 12.6 68 91 351 83 79.6 4 11.8

Example VIII

A catalyst according to example IV is prepared, but now 124 g of La (NO2) 2 are dissolved. δΗ ^ Ο in 300 cm of water and add to the solution to provide lanthanum in a catalyst of the following composition (based on the original solutions): 20

La 4

Mo._Co.Fe_Bi.Tl _Sbn, Si. ' NiiCs. -K. , 0.

12 4 3 1 0.5 0.3 6.6-2.3 0.3 j

Example IX

A catalyst according to example IV is prepared, but now it is dissolved with 76.2 g (NH.). W_0 ". . H_0 in 300 cm of water and add 467 24 2 to the solution to provide tungsten in a catalyst of the following composition (based on the original solutions):

Wj

Mo. Co. Fe0Bi Tl rSb Si Hi ^ Cs ^ 0.

12 4 3 1 0.5 0.3 6.6 2 ^ 0.3 0.3 y 30

In addition to the effect of the reconditioned catalyst composition, it is believed that it is important to maintain the specific surface area of the catalyst within a relatively narrow range, globally 2 van 0.5-10 m / g and preferably 2-6 m / g measured according to the BET method.

The specific surface is related to the pore size, one of them

79 0 6 4 8 C

A particle with many small pores would have a large specific surface area and a particle with only large pores would have a relatively small specific surface area. Heating the catalyst for a sufficiently long time

time to a temperature of at least 525 C and preferably above 550 C

5 appears to have the effect of eliminating the smaller pores and thus reducing the specific surface area. Although calcination of the catalyst is preferred for use at about 600 ° C, calcination at somewhat lower temperatures, at least about 525 ° C, can be performed when the specific surface area of the final catalyst is below about 10 m / g and at preference is below about 26 m / g, as will be apparent from the following Example X.

Example X.

A catalyst according to example IV is prepared to obtain a catalyst of the following composition (based on the original solutions): M ° 12C ° 4Pe3Bll'rl0.5Sb0.3S ± 6.6Ni2Cs0.3K0.3 ° j * 20. heat the catalyst to about 550 ° C for 3 hours during the 2 calcination to give a specific surface area of 9.6 m / g and test the catalyst with a feed composition of 5.4 vol% isobutene, 9.8 vol. % oxygen, 16 vol.% steam and the remainder nitrogen and a pressure of 3.4 kg / cm2 absolute, a temperature of about 335 ° C and a space velocity of about 3000 hours 1 with the following results: 7906480 20

TABLE G

Trial Duration in iC ^ = Methacrolein Vinegar- CO + ar. hour conversion + methacrylic acid CO ^ _% acid___ 5 69 8 74.6 82.15 2.58 8.01 70 10 73.5 82.25 2.50 8.07 71 12 74.2 82.73 2, 54 7.83 72 14 74.5 82.64 2.30 8.24 73 26 68.5 82.5 2.51 8.2 10

Example XI

At a catalyst of the composition

Mo. "Co.Fe_.Bi.Tl ,. -Sb ,. Si_Ni_Cs K o. A total specific 12 4 3 1 0.5 ° r ° 2 surface of 23 m / g is measured after calcination with temperatures up to a maximum of 280 ° C. The pore volume was measured by the mercury porosimeter method and it was found to be 0.3 cm / g and the pore distribution by the same method was found to be such that 70% of the internal surface of the catalyst belongs to pores with a diameter of 100.10 * ^ m and larger and 30% of the internal surface area of pores smaller than 100.10 ^ m. The average 20 pore diameter is 1600.10 10 m.

A catalyst identical to that described above is prepared, but the mixture is now calcined at 600 ° C for 3 hours in air. The pore volume remains 0.3 cm3 / g but the total specific surface 2 appears to be 6.24 m / g and 97% of the internal specific surface belongs to pores of 100.10 µm in diameter and larger and only 3 % of the internal surface area with pores smaller than 100.10 ^ m diameter. The average diameter is 3660.10 ^ m.

As can be seen from Example XI, one effect of heating the catalyst to above normal temperatures is to reduce the specific surface area by eliminating the pores with a diameter of less than about 100.10 m, which has the effect of increasing the average pore diameter. Other effects can also be important.

7906480

Claims (7)

Catalyst composition suitable for the vapor phase oxidation of isobutene and / or tertiary butyl alcohol to methacrolein, characterized in that it consists essentially of the oxides of molybdenum, cobalt, iron, bismuth, thallium, antimony, silicon, nickel and a member of the trench consisting of the alkali metals, alkaline earth metals, rare earth metals, including lane, tungsten and mixtures thereof. Catalyst composition according to claim 1, characterized in that it is calcined in air at a temperature of at least about 525 ° C for a time sufficient to reduce the BET specific surface area to a predetermined value. Catalyst according to claim 1, characterized in that it has the formula Mo Co. Fe Bi .Tl Sb-Si Ni.X.O. wherein X is one or more abcdefghio members of said group of alkali metals, alkaline earth metals, rare earth metals including lanthanum, tungsten and mixtures thereof, and wherein a = 12, b = 0.2-8, c = 0.05 -5, d = 0.2-4, e = 0.01-5, f = 0.01-5, g = 1-20, h = 0.05-5, i = a positive number up to 4, and j depends on the valence and amounts of the other elements. Catalyst composition according to claim 1, 2, characterized in that the BET specific surface area lies between 0 - 5-10 m / g catalyst. 5 Mo Co, Fe Bi.Tl Sb_Si Ni. X.o. wherein X represents one or more members abcdefghlj of said group of alkali metals, alkaline earth metals, rare earth metals including lanthanum, tungsten and mixtures thereof, and wherein a = 12, b = 0.2-8, c = 0.5-5, d = 0.2-4, e = 0.01-5, f = 0.01-5, g = 1-20, h = 0.05-5, i = a positive number up to 4 and j is dependent of 10 the valence and quantities of the other elements » Process according to claim 7, characterized in that said catalyst composition has a BET specific surface area 2 between 0.5-10 m / g catalyst. 10. Process according to claim 9, characterized in that the BET specific surface area is between 2-6 m / g catalyst and no more than about 3% of the specific surface area of said catalyst belongs to pores with a diameter of less than 100.10 m. 11. Catalyst composition suitable for the vapor phase oxidation of isobutene and / or tertiary butyl alcohol to form methacrolein and containing molybdenum, cobalt, iron, bismuth, thallium, antimony and silicon, characterized in that catalytically effective amounts of nickel are added and a member of the group consisting of alkali metals, the alkaline earth metals, rare earth metals including lanthanum, tungsten and mixtures thereof, and said catalyst is calcined for use in said oxidation, at a temperature of at least 525 ° C in air to decrease the BET specific surface area 2 to the range of about 0.5-10 m / g. Catalyst composition according to claim 11, 2, characterized in that the BET specific surface area is between 2-6 m / g 30 catalyst and no more than about 3% of the specific surface area of said catalyst belongs to pores with a diameter of less than 100.10 "10 m. Catalyst composition according to claim 11, characterized in that it has the formula Mo Co Fe Bi Tl Sb. Si Ni XO, - abcdefghij 35 wherein X is one or more members of said group of alkali metals, earth 7906480 -y · ► 23 represents alkali metals, rare earth metals, including lanthanum and tungsten, and wherein a = 12, b - 0.2-8, c = 0.05-5, d = 0.2-4, e = 0.01-5, f = 0.01-5, g = 1-20, h - 0.05-5, i = a positive number of up to 4, and j depends on the valency and amounts of other elements. 14. A process for preparing a silica-containing metal oxide catalyst for the vapor-phase oxidation of isobutene and / or tertiary butyl alcohol to methacrolein, characterized in that a dried mixture of colloidal silicon oxide and aqueous base metal solutions is calcined in air. a temperature of at least 525 ° C for a time sufficient to reduce the BET specific surface area 2 to the range of about 0.5-10 m / g catalyst. 15. Process according to claim 14, characterized in that the BET specific surface area is between 2-6 m / g catalyst and no more than about 3% of the surface area of said catalyst belongs to pores of diameter smaller than 100.10 m. 16. Any of the processes or products or devices or any combinations thereof, substantially as described herein. Catalyst composition according to claim 4, characterized in that the BET specific surface area is between about 2 2-6 m / g catalyst and not more than about 3% of the surface area of said catalyst consists of pores with a diameter smaller than 100.10 "10 m. 6. Process for the preparation of methacrolein, characterized in that isobutene and / or tertiary butyl alcohol is oxidized in the vapor phase with molecular oxygen in the presence of a catalyst composition consisting essentially of the oxides of molybdenum, cobalt, iron, bismuth, thallium, antimony, nickel, silicon and a member of the group consisting of the alkali metals, the alkaline earth metals, the rare earth metals including lanthanum, tungsten and mixtures thereof. A method according to claim 6, characterized in that said catalyst composition is calcined in air at a 7906480 -V-22 temperature of at least about 525 ° C for a time sufficient to reduce the BET specific surface area to a predetermined value. , Process according to claim 6, characterized in that said catalyst composition has the formula 7 JU) 6 4 8 0 / v-y