Process for producing methacrolein and methacrylic acid
United States Patent [1 1 Ono et al.  
 [451 Apr. 22, 1975 7 [75] Inventors: lsao Ono; Teruhisa Sakamoto;  
 Toshio Hironaka, all of Yamaguchi, Japan [73] Assignee: Toyo Soda Manufacturing Co., Ltd., Yamaguchi, Japan [22] Filed: May 30, 1973 [21] Appl. No.: 365,100  
 [30] Foreign Application Priority Data May 30. I972 Japan 47-53662 Aug. 2, I972 Japan 47-77469 [52] U.S. Cl 260/533 N; 252/456; 252/464:  
  252/469; 252/467; 260/604 R [51] Int. Cl C07c 51/32; C07c 57/04 [58] Field of Search 260/533 N, 604 R [56] References Cited UNITED STATES PATENTS 3,574,729 4/l97l Ganon 260/530 N 3.736.355 5/1973 Croci et al. 260/533 N FOREIGN PATENTS OR APPLICATIONS 97l.666 9/1964 United Kingdom 260/533 N 2,050,155 5/l972 Germany 260/530 N Primary Examiner-Lorraine A. Weinberger Assistant Examiner-Richard D. Kelly Attorney, Agent. or Firm-Oblon, Fisher, Spivak, McClelland &amp; Maier [57] ABSTRACT Methacrolein and methacrylic acid are produced by the catalytic oxidation of isobutylene in the vapor phase with molecular oxygen over a catalytic amount of a mixture of solid metal oxides, represented by the empirical formula Sb,,V,,Mo Te,,W ,M,O wherein M represents at least one element selected from the group consisting of bismuth, thallium and uranium, and wherein the elemental atomic ratios of said empirical formula have values of a=l0, b=0. ll0, c=0.4-l 5, d=0.l-l0, e=02, #0-2 and g=l6-l27, so as to satisfy the empirical formula.  
 12 Claims, No Drawings PROCESS FOR PRODUCING METIIACROLEIN AND METHACRYLIC ACID BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing methacrolein and methacrylic acid in high yields by the vapor phase catalytic oxidation of isobutylene. More particularly, it relates to a process for the vapor phase catalytic oxidation which comprises the use of a novel multi-component catalytic system consisting of antimony, vanadium, molybdenum and tellurium and- /or tungsten and one or more elements selected from the group consisting of bismuth, thallium and uranium.  
 2. Description of the Prior Art Substantial research has been done on methods for producing methacrolein and methacrylic acid by the catalytic vapor phase oxidation of isobutylene. Numerous catalyst systems have also been studied and reported for this oxidation reaction. Of primary importance, from the industrial point of view, is the achievement of the highest possible single-pass yield of useful products, because it is generally uneconomical to recover and recycle unreacted isobutylene. However, as the conversion rate of isobutylene is increased, the quantity of undesirable products produced, such as carbon dioxide, carbon monoxide and acetic acid also increases because of gradual oxidative decomposition. This causes a decrease in the selectivity for methacrolein and methacrylic acid. In addition to the requirement for high single-pass yields of product the catalyst system must also have a sufficient activity as well as possess a sufficient lifetime so as to be useable in industrial applications.  
  Although various catalyst systems have been reported in connection with the production of methacrolein and methacrylic acid from isobutylene, satisfactory results have not been attained with these systems. For instance, Japanese Patent Publ. No. 9872/1964 discloses an oxide catalyst system consisting of molybdenum, vanadium and phosphorus and Japanese Patent Publn. No. 3164/1968 discloses an oxide catalyst system consisting of molybdenum, vanadium and bismuth. In both of these catalyst systems extremely high reaction temperatures, ranging from 450 to 550C are required, which shortens the lifetime of the catalysts. Also the single-pass yields of methacrolein and methacrylic acid are insufficiently low. Thus, both of these catalyst systems are considered to be industrially unsatisfactory.  
  Example 3 of Japanese Patent Publn. No. 19485/1970 discloses the use ofa catalyst system consisting of molybdenum, antimony, tellurium, and sodium or potassium which produces a fairly good singlepass yield of methacrolein and methacrylic acid. However, the activity of the catalyst is insufficient, and also the lifetime of the catalyst is limited when sodium or potassium are lacking. In another catalyst system consisting of iron, antimony, tellurium and vanadium (or molybdenum or tungsten) as disclosed in Japanse Patent Publn. No. 1607/1972, a high combustion rate of isobutylene is achieved resulting in single-pass yields of methacrolein which amount to only about 60 percent, with the by-product of methacrylic acid limited to only about 1 to 2 percent.  
  A need, therefore, exists for a catalyst system which promotes the oxidative conversion of isobutylene to methacrolein and methacrylic acid in high single-pass yields while achieving high selectivity for methacrolein and methacrylic acid.  
 SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to 7 provide a catalyst system which promotes the oxidative conversion of isobutylene to methacrolein and methacrylic acid in high yields and high selectivity.  
  Another object of the present invention is to provide a multicomponent catalyst system for the oxidative conversion of isobutylene which contains antimony in addition to at least three other polyvalent metal elements.  
  Briefly, these objects and other objects of the invention as hereinafter will become readily apparent can be achieved by use of a solid metal oxide catalyst for the vapor phase, catalytic oxidation of isobutylene with molecular oxygen which comprises a mixture of metal oxides having the empirical formula Sb V Mo Te W,.M,0,,, wherein M represents one or more elements selected from the group consisting of bismuth, thallium and uranium and wherein the elemental atomic ratios of said empirical formula have values of a=l0, b=0.1-l0, c=0.4-l5, d=O.l-l0, e=02, f= 02 and g=l6l27, so as to satisfy the empirical formula.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention for the catalytic conversion of isobutylene to methacrolein and methacrylic acid in high yields a solid metal oxide catalyst system is used which is represented by the empirical formula Sb,,V,, Mo Te W Mp wherein M is one or more elements selected from the group consisting of bismuth, thallium and uranium and a, b, c, d, e,fand g are the atomic ratios of the elements. The atomic ratios encompass the ranges ofa=l0, b=0.l-lO, c=O.4-l5, d=0. l-lO, e=0-2, FO-Z and g=l6-l27. Optimum catalyst performance is obtained when the atomic ratios in the catalyst compositions preferably encompass the ranges of 0 10, b=1-4, c=l-8, a=28, e=().ll and f=().1l and g satisfies the empirical formula.  
  The catalyst of the present invention may be employed as is, or it may be mixed with a suitable carrier such as diatomaceous earth, silica, alumina, titanium oxide, carborundum pellets, zirconium oxide to improve the physical strength, thermal stability, reactivity, selectivity and the like of the catalyst. Although the catalyst of this invention may be prepared by any of several conventional methods, it is preferably prepared by uniformly mixing aqueous solutions of each component followed by isolating and drying the mixture.  
  In one embodiment of the preparation, for example, a catalyst is prepared which uses antimony trioxide as the source of antimony, ammonium meta-vanadate as the vanadium source, tellurium dioxide as the tellurium source, ammonium molybdate as the molybdenum source, ammonium tungstate as the tungsten source, bismuth nitrate as the bismuth source, thallium trichloride or thallium nitrate as the thallium source and uranyl nitrate as the uranium source. First, ammonium molybdate is dissolved in warm water into which an aqueous solution of ammonium metavanadate is dissolved and mixed. Aqueous solutions of ammonium tungstate and/or tellurium dioxide are added to the mixture and thoroughly stirred. Aqueous solutions of reaction may be carried out at temperatures ranging a wide range, but it is preferable to use a feed gas combismuth nitrate and/or thallium trichloride and/or urapercent isobutylene, about 60 mole percent air and nyl nitrate are added, and antimony trioxide is mixed about 35 mole percent steam was fed into the reactor in the composition. The composition is thoroughly while it was heated. The apparent contact time was sestirred, and then is concentrated by evaporation. If delected to fall within the range of 4 to 7 seconds at a consired, a suitable carrier material as indicated above may stant reaction temperature in the range of 360 to be added. The slurry is further concentrated and dried, 430C. The gas evolved from the reactor was cooled by and then calcined in air at a temperature in the range an ice water solution and by a dryice methanol soluof 400 to 600C. The calcination temperature is not tion. After passage of the gas through the cold traps, critical, but it is desirable to conduct the calcination at the evolved gas and the liquids trapped in the dry-ice a temperature of 460 to 540C for several hours. 10 bath were analyzed by gas chromatography and par- Suitable reactors for the oxidation of isobutylene intially by titrimetry and the constituents and their reclude either fixed bed or fluid bed reactors which conspective quantities were determined.  
 tain the catalyst of this invention. The gas fed to the re- EXAMPLE 1 actors is composed of isobutylene and molecular oxygen to which nitrogen, carbon dioxide, steam or the like may optionally be added as an inert diluent. The  
 Is An 18.0 gram amount of ammonium paramolybdate (NH Mo O .4l-l O was dissolved in 400cc of distilled water, and 11.6 grams of ammonium metavanadate NH VO was added and dissolved in the molybdate solution with stirring while being heated over a hot water bath. An 8.0 gram amount of tellurium dioxide TeO and 73.2 grams of antimony trioxide Sb O were added to the solution and it was thoroughly stirred. The resulting solution was concentrated by evaporation and the residue was dried. The dried residue was punched into 25 tabloids of 3mm diameter which were calcined at a temperature of 520C for 5 hours. A catalyst having a composition of Sb:V:Mo:Te=10:2:2:1 (atomic ratio) was obtained in this manner.  
  The oxidative conversion of isobutylene was conducted over this catalyst at a reaction temperature of 400C and a contact time of 5.0 seconds. The results are shown in Table I wherein the conversion of isobutylene is 96.4 percent, the selectivities of methacrolein and methacrylic acid 74.0 and 7.6 percent respectively; and the composite single-pass yield of methacrolein from 250 to 500C, preferably ranging from 350 to 420C. Though the apparent contact time of the reactants greatly varies according to the reaction tempera- 20 ture and the composition of the feed gas, a range of 0.5 to 20 seconds, preferably a range of l to 12 seconds is suitable. The composition of the feed gas may vary over position which is in the range of l to 10 mole percent isobutylene, 20 to 90 mole percent air and l to 50 mole percent steam.  
  The isobutylene which is used as the raw material of the invention need not be ofa high purity. Even if other saturated or unsaturated hydrocarbons such as ethylene, propylene, propane, butane, and the like are present, these substances are not oxidized but merely pass through the reactor, as would any inert diluent. Similarly it is not always necessary to use pure oxygen as the source of oxygen. Air is a suitable source of oxygen and and methacrylic acid is 78.6 percent. 15 desirable for economical reasons.  
  By using the catalyst of this invention in conventional EXAMPLE 2 processes, such as is disclosed in Japanese Patent A catalyst with a composition of Sb:V:Mo:- Publn. No. 7881/1967, it is possible to produce meth- Te=l0g2:4:2 t i ratio) was prepared in a manner acrolein and methacrylic aCid from isob yl n and similar to that described in Example 1. The oxidative simultaneously butadiene from n-butenes by the oxidaconversion was conducted under the same reaction tion of a C hydrocarbon fraction. conditions as described in Example 1. The results ob- Having generally described this invention, a further tained are shown in Table I, wherein the conversion of understanding can be obtained by reference to certain isobutylene is 97.5 percent, the selectivity of methacro- 5 specific examples which are provlded herein for purlem is 76.0 percent, the selectivity of methacrylic acid pose of illustration only and are not intended to be limis 5.3 percent, and the composite single-pass yield of iting unless otherwise specified. The terms conversion methacrolein and methacrylic acid is 79.3 percent. of isobutylene, selectivity and single-pass yield EXAMPLE 3 which are used herein are defined by the following A catalyst having a Composition f ;\/;M equations- Te=l0:3:2:2 (atomic ratio) was obtained in a manner moles of isobutylene converted moles of isobutylene fed carbon number of each product moles of each product X Conversion of isobutylene Selectivity moles of isobutylene converted x 100% carbon number of each product moles of each product X Single-pass yield )K 100% moles of isobutylene fed The results of the experiments using the catalyst of similar to that described in Example 1. The oxidative this invention are shown in the examples and a number conversion of isobutylene was conducted under the of comparative examples, were conducted using the exsame reaction conditions described in Example 1. The perimental procedure described below. results obtained are shown in Table I, wherein the con- A 20 gram amount of a catalyst in tablet form with version of isobutylene is 99.8 percent, the selectivities a diameter of 3mm was placed in a fixed bed tubular of methacrolein and methacrylic acid are 67.2 and 10.2 reactor made of pyrex glass having an inside diameter percent respectively, and the composite single pass of 20mm. The reactor was immersed in a tubular elecyield of methacrolein and methacrylic acid is 77.2 pertric furnace, and a gas mixture containing about 5 mole cent.  
 EXAMPLES 4, 5, and 6 Te=10:2:3: l .6 (Example 6) were prepared in a manner similar to that described in Example 1. The oxidative conversion of isobutylene was conducted with the catalysts prepared in the manner indicated. The results obtained are shown in Table 1, wherein the conversion of shown in Table I, wherein the conversion of isobutylene is 89.7 percent, the selectivities of methacrolein and methacrylic acid are 27.2 and 12.3 percent respectively and the composite single-pass yield of methacrolein and methacrylic acid is 35.4 percent.  
 COMPARATIVE EXAMPLE 3 A catalyst having a composition of Sb:Te:Mo=l 0:2:2 (atomic ratio) was obtained in a manner similar to that isobutylene is 94.2 percent, the selectivities of methacdescrbed m 35 2 iff that at; a l rolein and methacrylic acid are 72.6 and 6.21 percent i 3 l e m g d e f f respectively and the composite single-pass yield of 3 uty i i con i ti methacrolein and methacrylic acid is 74.2 percent for o i a 3 enpera ure 0 3 Example 4; the conversion of isobutylene is 92.3 per- 5 0 H I h th cent, the selectities of methacrolein and methacrylic S 9 2 a e C i .9 m; acid are 74.8 and 5.2 percent respectively and the comi 15(1) y 3 ls th F e g fg h f posite single-pass yield of methacrolein and methi sg gg i g i gz i; acrylic acid is 73.8 percent for Example 5; and the conpield of metgacroleii and methacr 8 p 5 version of isobutylene is 96.8 percent, the selectivities 2O g y of methacrolein and methacrylic acid are 70.8 and 6.7 percent respectively, and the composite single-pass COMPARATIVE EXAMPLE 4 yield of methacrolein and methacrylic acid is 75.0 per- A catalyst having a composition of Mon-6:242 Cent for Example (atomic ratio) was obtained in a manner similar to that COMPARATIVE EXAMPLE 1 described in Example 1 except that the antimony coml pound was not added in this case. The oxidative con- A Q havmg CPmPQSmOn of y- 5 1 1 version of isobutylene was conducted with the catalyst (atomic rat1o) was obtalned In a manner Slml ar to t at obtained at a reaction temperature of 420C with 3 described in Example 1 except that the molybdenum Contact time of seconds compoufld not added thls Case and h oxldatwe The results are shown in Table I, wherein the converconversl?&#34; oflsobutylelle was conducted P sion of isobutylene is 93.7 percent, the selectivities of lyst 9 at a reacuon temperature of 435 C methacrolein and methacrylic acid are 62.0 and 4.6 a Contact of Secondspercent respectively, and the composite single-pass The results obtijlmed are shown m Table wherem yield of methacrolein and methacrylic acid is 62.4 perthe conversion ofisobutylene 15 94.0 percent, the seleccent tivities of methacrolein and methacrylic acid are 57.6 and 6.3 percent respectively and the composite single- COMPARATIVE EXAMPLE 5 pass yield of methacrolein and methacrylic acid is 60.0 A catalyst having a composition of V:Mo:Te=6:8:1 percent. (atomic ratio) was obtained in a manner similar to that 40 described in Comparative Example 4, and the oxidative COMPARATIVE EXAMPLE 2 conversion of isobutylene was conducted over the cata- A catalyst having a composition of Sb:V:Mo=l0=2:2 lyst obtained at a reaction temperature of 400C with (atomic ratio) was prepared in a manner similar to that a contact time of 5.0 seconds. The results obtained are described in Example 1 except that the tellurium comshown in Table 1, wherein the conversion of isobutyl-- pound was not added in this instance. The oxidative ene is 89.0 percent, the selectivities of methacrolein conversion of isobutylene was conducted with the cataand methacrylic acid are 42.3 and 9.6 percent respeclyst obtained at a reaction temperature of 440C with tively, and the composite single-pass yield of methacroa contact time of 4.8 seconds. The results obtained are lein and methacrylic acid is 46.3 percent.  
 TABLE I Con- Catalyst Composition ver- Composite (in atomic ratio) Reaction Condition sion Selectivity 71 single-pass Sb V Mo Te W Reaction Conc. Contact of MAL MAA Acetic CO; CO yield of MAL g pof iso- Ilme iso acid and MM A C butylcnc but- 7: ylenc 1 10 2 2 1 0 400 5.36 5.0 96.4 74.0 7.6 3.8 8.6 4.0 78.6 2 10 2 4 2 0 400 5.12 5.0 97.5 76.0 5.3 4.7 7.9 4.7 79.3 3 10 3 2 2 0 400 5.61 5.0 99.8 67.2 10.2 3.3 11.7 6.0 77.2 4 10 2 8 2 O 415 5.24 5.4 94.2 72.6 6.2 5.0 10.2 5.4 74.2 5 l0 2 3 6 0 420 5.18 6.0 92.3 74.8 5.2 4.8 9.2 4.3 73.8 6 10 2 3 1.6 0 400 5.60 5.0 96.8 70.8 6.7 4.2 9.4 4.2 75.0 Com P rative Note:  
 MAL: Methacrolein MAA: Math-acrylic acid EXAMPLE 7 A 21.6 gram amount of ammonium paramolybdate (NH Mo O .4H O was dissolved in 400cc of water and 11.6 grams of ammonium metavanadate NH VO were added to the solution. The added material was dissolved by stirring over a hot water bath. Then 4.8 grams of bismuth nitrate (Bi(NO .51-l O as a fine powder, and 16.0 grams of tellurium dioxide TeO were added to the solution with thorough stirring. Finally 73.2 grams of antimony trioxide Sb O were added and the solution was further stirred thoroughly.  
  The resulting solution was concentrated by evaporation and the residue obtained was dried. The dried residue was punched into tabloids with a diameter of 3mm, and was further dried and calcined at 500C for hours. A catalyst having a composition of Sb V Mo ,Te Bi (atomic ratio) was prepared in this manner.  
  The oxidative conversion of isobutylene was conducted with the catalyst prepared at a reaction temperature of 400C with a contact time of 4.6 seconds. The results obtained are shown in Table 11, wherein the conversion of isobutylene is 99.0 percent, the selectivities of methacrolein and methacrylic acid are 67.4 and 14.6 percent respectively, and the selectivities of acetic acid, carbon dioxide and carbon monoxide are 2.8, 8.6 and 5.0 percent respectively. As a consequence, the single-pass yield of methacrolein and methacrylic acid was 81.2 percent.  
 EXAMPLE 8 A catalyst having a composition of Sb V Mo Te Bi (atomic ratio) was prepared in a manner similar to that described in Example 7. The oxidative conversion of isobutylene was conducted over the catalyst prepared at a reaction temperature of 400C with a contact time of 4.6 seconds. The results are shown in Table 11, wherein the conversion of isobutylene is 99.5 percent, the selectivities of methacrolein and methacrylic acid are 67.8 and 12.8 percent respectively and the composite single-pass yield of methacrolein and methacrylic acid is 80.2 percent.  
 EXAMPLE 9 A catalyst having a composition of Sb V Mo Te W Bi (atomic ratio) was prepared in a manner similar to that described in Example 7 except that 100cc of an aqueous solution containing 3.9 grams of ammonium paratungstate was added to the solution prior to the addition of bismuth nitrate.  
  The oxidative conversion of isobutylene was conducted over the catalyst obtained at a reaction temperature of 380C with a contact time of 4.6 seconds. The results obtained are shown in Table 11, wherein the conversion of isobutylene is 99.2 percent, the selectivities of methacrolein and methacrylic acid are 63.4 and 15.8 percent respectively, the single-pass yield of methacrylic acid is 15.7 percent and the composite singlepass yield of methacrolein and methacrylic acid is 78.6 percent.  
 EXAMPLE 10 A catalyst having a composition of Sb V Mo Te Tl (atomic ratio) was prepared in a manner similar to that described in Example 7, except that an aqueous solution of thallium trichloride was used instead of a solution of bismuth nitrate. The oxidative conversion of isobutylene was conducted over the catalyst obtained at a reaction temperature of 400C with a contact time of 5.0 seconds. The results obtained are shown in Table 11, wherein the conversion of isobutylene is 96.8 percent, the selectivities of methacrolein and methacrylic acid are 67.6 and 15.3 percent respectively, the single-pass yield of methacrylic acid is 14.7 percent, and the composite single-pass yield of methacrolein and methacrylic acid is 80.2 percent.  
 EXAMPLE 1 l A catalyst of a composition of Sb V Mo Te Tl (atomic ratio) was prepared in a manner similar to that described in Example 10. The oxidative conversion of isobutylene was conducted at a reaction temperature of 400C with a contact time of 5.0 seconds. The results obtained are shown in Table 11, wherein the conversion of isobutylene is 94.9 percent, the selectivites of methacrolein and methacrylic acid are 72.8 and 12.3 percent respectively, and the selectivities of acetic acid, carbon dioxide and carbon monoxide are 2.6, 6.3 and 2.8 percent respectively. As a consequence, the singlepass yield of methacrylic acid was 1 1.7 percent and the composite single-pass yield of methacrolein and methacrylic acid was 80.8 percent.  
 EXAMPLE 12 A 47.7 gram amount of ammonium paramolybdate (NH Mo O .,.41-1 O was dissolved in 600cc of water and 31.6 grams of ammonium methavanadate NHNO were added thereto. The vanadate material was dissolved by stirring the mixture over a warm water bath. To this solution was added cc of an aqueous solution containing 20.7 grams of thallium trichloride TlCl .41l O and the solution was thoroughly stirred. Next, 28.7 grams of tellurium dioxide was added with stirring to the solution. Then, after 157.4 grams of antimony trioxide were added and thoroughly mixed in the solution, 29.1 grams of diatomaceous earth was added with continuous stirring. The resulting solution was concentrated by evaporation and the residue was dried. The dried residue was punched into tabloids with a diameter of 3mm and was dried and calcined at 500C for 5 hours. A catalyst of a composition of Sb, V Mo Te Tl (atomic ratio) containing 10 percent by weight diatomaceous earth carrier was prepared in this manner.  
  The oxidative conversion of isobutylene was conducted over the catalyst obtained in this way at a reaction temperature of 400C with a contact time of 4.2 seconds. The results showed a 99.1 percent conversion of isobutylene, a 63.0 percent selectivity of methacrolein, and a 17.8 percent selectivity of methacrylic acid. The selectivities of acetic acid, carbon dioxide and carbon monoxide were 3.9, 9.8 and 4.5 percent respectively. As a consequence, the single-pass yield of methacrylic acid was, as shown in Table II 17.6 percent and the composite single-pass yield of methacrolein and methacrylic acid was 80.1 percent.  
 EXAMPLE 13 A catalyst having a composition of Sb, V Mo Te W Tl (atomic ratio) was obtained in a manner similar to that described in Example 9 except that thallium trichloride was used instead of bismuth nitrate.  
  When the oxidative conversion of isobutylene was conducted over the catalyst obtained at a reaction temperature of 390C with a contact time of 4.6 seconds, results were obtained which are shown in Table 11, wherein the conversion of isobutylene is 95.3 percent,  
 the selectivities of methacrolein and methacrylic acid are 64.8 and 16.0 percent respectively, the single-pass yield of methacrylic acid is 15.2 percent, and the composite single-pass yield of methacrolein and methacrylic acid is 77.0 percent.  
 EXAMPLE 14 A catalyst of a composition of Sb V Mo Te w Bi Tl,, (atomic ratio) was prepared in a manner similar to that described in Example 9 except that thallium trichloride was added to the solution after the addition of bismuth nitrate.  
  The oxidative conversion of isobutylene was conducted over the catalyst prepared in this way at a reaction temperature of 386C with a contact time of 4.6 seconds. The results obtained are shown in Table 11, wherein the conversion of isobutylene is 98.3 percent, the selectivites of methacrolein and methacrylic acid are 61.7 and 16.5 percent respectively, the single-pass yield of methacrylic acid is 16.2 percent, and the composite single-pass yield of methacrolein and methacrylic acid is 76.9 percent.  
 EXAMPLES 15, 16, 17  
  Catalysts of compositions (atomic ratios) of V2M03Te U (Example Sb 0V Mo Te U0 4 (Example 16) and Sb, V Mo Te U (Example 17) were prepared in a manner similar to that described in Example 7 except that uranyl nitrate was added to the mixture instead of bismuth nitrate. The subsequent oxidative conversions of isobutylene with each catalyst prepared were conducted at a reaction temperature of 380C with a contact time of 5.0 seconds. As shown in Table II, the best catalytic performance was obtained when the atomic ratio of uranium was about 0.2 in relation to Sb=l0.  
 EXAMPLE 18 A catalyst of a composition of sb.,,v,Mo,Te U, Bi (atomic ratio) was prepared in a manner similar to that described in Example 7, except that uranyl nitrate was added to the mixture after the addition of bismuth nitrate. The oxidative conversion of isobutylene was conducted with the catalyst obtained at a reaction temperature of 380C with a contact time of 4.6 seconds. The results obtained are shown in Table 11, wherein the conversion of isobutylene is 98.0 percent, the selectivity of methacrolein is 64.2 percent, the single-pass yield of methacrylic acid is 17.0 percent, and the composite single-pass yield of methacrolein and methacrylic acid is 79.9 percent.  
 EXAMPLE 19 A catalyst having a composition of Sb V Mo Te W U Bi (atomic ratio) was prepared in a manner similar to that described in Example 18 with the addition of tungsten. The oxidative conversion of isobutylene was conducted at a reaction temperature of 375C with a contact time of 4.6 seconds. The results are shown in Table 11, wherein the conversion of isobutylene is 98.5 percent, the selectivities of methacrolein and methacrylic acid are 61.3 and 15.1 percent respectively, the single-pass yield of methacrylic acid is 14.9 percent, and the composite single-pass yield of methacrolein and methacrylic acid is 75.3 percent.  
 EXAMPLE 20 The oxidative conversion of isobutylene was conducted in the presence of 20 grams of the catalyst of Example 7. The composition of the gaseous mixture fed to the catalyst zone consisted of 5.6 mole percent isobutylene, 5.4 mole percent 1butene, 54 mole percent air and 35 mole percent steam at an apparent contact time of 5.0 seconds at a reaction temperature of 396C.  
  The results obtainedshowed a 94.8 percent conversion of isobutylene, selectivities for methacrolein and methacrylic acid of 70.5 and 14.5 percent respectively and selectivities for carbon dioxide, carbon monoxide and acetic acid of 7.5, 3.2 and 4.3 percent respectively. As a consequence, the single-pass yield of methacrylic acid was 13.7 percent and the composite single-pass yield of methacrolein and methacrylic acid was 80.6 percent. The results also showed that 27.8 percent of the l-butcne in the gaseous raw material had reacted, and that the selectivity for product butadiene was 69.2 percent and the selectivities for trans-2 butene and cis- Z-butene were 1 1.4 and 15.6 percent respectively.  
 EXAMPLE 21 The oxidative conversion of isobutylene was conducted with 20 grams of the catalyst of Example 7 by feeding a gaseous raw material gas having a composition of 10 mole percent of a C hydrocarbon fraction composed of 42 mole percent isobutylene,-27 mole percent l-butene, 10 mole percent trans-2-butene, 7 mole percent cis-2-butene, 10 mole percent n-butane, 55 mole percent air and 35 mole percent steam with an apparent contact time of 5.0 seconds at a reaction temperature of 400C.  
  The results obtained showed a 95.7 percent conversion of isobutylene, selectivities for methacrolein and methacrylic acid of 69.0 and 14.2 percent respectively, a single-pass yield of methacrylic acid of 13.6 percent, and a composite single-pass yield of methacrolein and methacrylic acid of 79.6 percent. The results also showed that 42.3 percent of the n-butenes had reacted and the selectivity of butadiene was 67.6 percent.  
 COMPARATIVE EXAMPLE 6 An 11.6 gram amount of ammonium metavanadate NHq VOg was dissolved in 400cc of water and 200cc of an aqueous solution containing 26.1 grams of uranyl nitrate UO (NO .6H O was added thereto and the combined solutions were thoroughly stirred. A 16.0 gram quantity of tellurium dioxide and 73.2 grams of antimony trioxide were added to the solution while being thoroughly stirred. The resulting mixture was concentrated by evaporation and the residue dried. The dried residue was punched into tabloids of 3mm diamter which were dried and calcined at 520C for 5 hours. The catalyst obtained in this manner had a composition of Sb V Te U (atomic ratio). The oxidative conversion of isobutylene was conducted over the catalyst obtained at a reaction temperature of 420C with a contact time of 5.0 seconds. The results obtained are shown in Table 11, wherein the conversion of isobutylene is 87.7 percent, the selectivities of methacrolein and methacrylic acid are 53.5 and 6.1 percent respectively, and the selectivities of acetic acid, carbon dioxide and carbon monoxide are 3.0, 24.3 and 9.1 percent respectively. As a consequence, the single-pass yield of methacrylic acid was 5.3 percent and the composite single-pass yield of methacrolein and methacrylic acid was 52.3 percent.  
 COMPARATIVE EXAMPLE 7 A catalyst having a composition of Sb Mo Te U (atomic ratio) was prepared in a manner similar to that =10, and  
  12 Having now fully described this invention, it will be apparent to one of ordinary skill in the art that many c=l-8, d=2-8, e=0.l-l, f=0.ll  
  What is claimed as new and intended to be covered by letters patent is:  
  I. A process for producing methacrolein and methacrylic acid which comprises reacting isobutylene with molecular oxygen in the vapor phase in the presence of a catalytic amount of a catalyst consisting essentially of a mixture of solid metal oxides represented by the empirical formula Sb V MO Te W M O wherein M represents at least one element selected from the group consisting of bismuth, thallium and uranium and 2. The process of claim 1, wherein the elemental tained at a reaction temperature of 420C h a 20 atomic ratios of said empirical formula are a contact time of 5.0 seconds. The results obtained are 1 4 shown in Table ll, wherein the conversion of isobutylene is 94.3 percent, the selectivities of methacrolein and methacrylic acid are 35.7 and 7.2 percent respecchanges and modifications can be made thereto without departing from the spirit or scope of the invention set forth herein.  
 wherein the elemental atomic ratios of said empirical formula have values of a=l0, b=0. l-lO, c=0.4-l5,  
  3. The process of claim 1, wherein the catalyst is supported by a carrier.  
  4. The process of claim 3, wherein said carrier is selected from the group consisting of diatomaceous earth, silica, alumina, titanium oxide, carborundum, and zirconium oxide.  
 5. The process of claim 1, wherein said oxidation of 30 isobutylene is conducted at a temperature in the range of 250 to 500C.  
  6. The process of claim 1, wherein said oxidation of isobutylene is conducted at a temperature in the range of 350 to 420C.  
  0.- lar to that described in Example 9 except that antimony trioxide was not added. The oxidative conversion of isobutylene was conducted over the catalyst obtained described in Comparative Example 6 except that 26.6 grams of ammonium molybdate were used instead of ammonium metavanadate. The oxidative conversion of isobutylene was conducted over the catalyst obtained at a reaction temperature of 425C with a contact time as of 5.0 seconds. The results obtained are shown in Table II, wherein the conversion of isobutylene is 82.1 percent, the selectivities of methacrolein and methacrylic acid are 57.6 and 4.1 percent respectively, the singlepass yield of methacrylic acid is 3.4 percent, and the composite single-pass yield of methacrolein and methacrylic acid is 50.7 percent.  
 COMPARATIVE EXAMPLE 8 A catalyst having a composition of Sb V Mo W Bi (atomic ratio) was prepared in a manner similar to that described in Example 9 except that tellurium dioxide was not added in this case. The oxidative conversion of isobutylene was conducted over the catalyst obtively, the single-pass yield of methacrylic acid is 6.8- percent, and the composite single-pass yield of methacrolein and methacrylic acid is 40.5 percent.  
 COMPARATIVE EXAMPLE 9 A catalyst having a composition of V Mo Te W gBiog (atomic ratio) was prepared in a manner simi at a reaction temperature of 430C&#39;with a contact time of 5.0 seconds. The results are shown in Table II,  
  7. The process of claim 1, wherein said oxidation of wherein the conversion of isobutylene is 87.2 percent, isobutylene is conducted at a Contact time in the range the selectivities of methacrolein and methacrylic acid of to 20 Secondsare 58.9 and 4.3 percent respectively, the single-pass The Process of Claim wherein the molecular oxyyield of methacrylic acid is 3.7 percent, and the comgen is Supplied in the form of air.  
  9. The process of claim 1, wherein said oxidation of isobutylene is conducted in the presence of an inert TABLE II Singlepass Yield MAL MAA  
 Reaction Condition Re- Cone.  
 action of isotemp. butylene time -pass yield of methacrolein and methacrylic acid is 55.1 percent.  
 Ex. Catalyst Composition (in atomic ratio) Sb V Mo Te W posite single Irllilllll- 28 2 063232462212 00.0 00000000000 0 B B W U B UUUBU U Note: MAL: Mclhacrulcin MAA: Mclhucrylic acid gaseous diluent.  
  10. The process of claim 9, wherein the inert gaseous diluent is selected from the group consisting of steam, nitrogen, and carbon dioxide.  
  1 1. The process of claim 1, wherein isobutylene is admixed with another saturated or unsaturated hydrocarbon gas.  
 12. The process for producing methacrolein and methacrylic acid which comprises oxidizing isobutylene with a mixture of air and steam, in the vapor phase, at a temperature in the range of 250 to 500C in which the concentration of isobutylene, air and steam are