MXPA00009533A - A catalyst useful for the gas phase oxidation of alkanes, alkenes or alcohols to unsaturated aldehydes or carboxylic acids - Google Patents

Abstract

A catalyst useful for oxidation reactions is disclosed. The catalyst is useful for the gas phase oxidation of alkanes, propylene, acrolein, or isopropanol to unsaturated aldehydes or carboxylic acids.

Description

TO A USEFUL CATALYST FOR OXIDATION REACTIONS This invention relates to a catalyst, which is useful for oxidation reactions. In particular, the invention relates to a catalyst, which is efficient in converting alkanes, alkenes or alcohols to aldehydes and unsaturated acids, and to a process for preparing these aldehydes and unsaturated acids with the use of the catalyst. The aldehydes and unsaturated acids are products important chemicals. Of particular importance is (meth) acrylic acid. The double bond and acid function, highly reactive, of (meth) acrylic acid, makes it especially suitable as a monomer, which can be polymerized only or with other monomers, to produce polymers important commercially. These unsaturated acids are also useful as a starting material for esterification in the production of commercially important (meth) acrylate esters. Materials derived from (meth) acrylic acids or esters are useful as sheets and pieces of plastic, paints and other coatings, adhesives, caulks, sealants, plastic additives and detergents, as well as other applications. lliii ifitfiim. -. *** & . * ,. , *. *. - - .. *. : ...

. . The production of unsaturated acids by the oxidation of an olefin is well known in the art. Acrylic acid, for example, can be manufactured commercially by the oxidation, in the gas phase, of propylene. It is also known that the more saturated carboxylic acids can also be prepared by the oxidation of the alkanes. For example, acrylic acid can be prepared by the oxidation of propane. Such a process is especially convenient, because alkanes have generally a lower cost than olefins. For example, at the time of submitting this application, propylene costs were approximately three times higher than that of propane. A suitable economic process for the oxidation of alkanes, as well as the oxidation of starting materials, to the saturated aldehydes, which is commercially viable, still has to be achieved. There is continuous research in the area of new catalysts and starting materials for the production of (meth) acrylic acid and (meth) acrolein. This research is generally aimed at reducing the cost of raw materials or increasing the performance of the oxidation process.

• - • - "^ HiiÉiiif An obstacle to the production of a commercially viable process in the catalytic oxidation of an alkane to an unsaturated acid, is the identification of a catalyst that has adequate conversion and selectivity, thus providing sufficient yield of the final product of the unsaturated acid U.S. Patent No. 5,380,933 discloses a method for the preparation of a catalyst useful in the oxidation of the gas phase from an alkane to a more saturated carboxylic acid. Prepares a catalyst by combining the ammonium metavanadate, telluric acid and ammonium paramolybdate to obtain a uniform aqueous solution.To this solution, niobium oxalate and ammonium is added to obtain an aqueous paste.The water is removed from the aqueous paste, obtain a solid catalyst precursor.This solid catalyst precursor is molded into a tablet, sieved to a particle size desired and then calcined at 600 ° C under a stream of nitrogen, to obtain the desired catalyst. The Patent Application, also pending, of the United States of America, No. 09/316007, discloses a process for preparing a catalyst, to catalyze an alkane in a - j., 1 .... ».",.-u- ***. &. *. . - ^. .. «- | üfi? Lt Ir-jni'-" - ** aldehyde or unsaturated carboxylic acid, where phase segregation is minimized and improvements in selectivity, conversion and yield are achieved. the references, there is a continuing need for new catalysts and improved processes for the production of (meth) acrylic acid and / or (meth) acrolein In one aspect of the present invention, a catalyst is provided, having the formula: AaMmNnXx0o where 0.25 < a < 0.98, 0.003 < m < 0.5, 0.003 < n < 0.5, 0.003 < x 0.5 and o is dependent on the oxidation state of the elements, and A is at least one of the Mo, W, Fe, Nb, Ta, Zr and Ru; M is at least one of V, Ce and Cr; N is al minus one of Te, Bi, Sb and Se; and X is at least one of Nb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B, In, and Ce; in which the catalyst exhibits at least two crystal phases, one phase includes major X-ray diffraction ridges in 22.1, 28.2, 36.2, 45.2, 50.5, 54.2, 55.4 and 58.5, and a second phase includes major X-ray diffraction crests in 22.1, 27.2, 35.3, 45.2 and 51.1. Í-á-a - n-Aa-c - i¿ - ^^^^^ _ J -_- ^ Ju- - * - .. ~, *** .. ** ^ *. *****, * ... ...... * *. . *.

In a second aspect of the present invention, a process for preparing aldehydes and saturated acids is provided, which includes subjecting an alkane to catalytic oxidation, in the presence of a catalyst having the formula: AaMmNnXx0o where 0.25 < a < 0.98, 0.003 < m < 0.5, 0.003 < n < 0.5, 0.003 < x < 0.5 and o is dependent on the oxidation state of the elements, and A is at least one of the Mo, W, Fe, Nb, Ta, Zr and Ru; M is at least one of V, Ce and Cr; N is at least one of Te, Bi, Sb and Se; and X is at least one of Nb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B, In, and Ce; in which the catalyst exhibits at least two phases of crystals, one phase includes major crests of X-ray diffraction in 22.1, 28.2, 36.2, 45.2, 50.5, 54.2, 55.4 and 58.5, and a second phase includes X-ray diffraction principal crests in 22.1, 27.2, 35.3, 45.2 and 51.1. In a third aspect, the present invention provides a process for preparing aldehydes and acids msaturated, which includes subjecting a compound, selected from propylene, acrolein and isopropanol to oxidation ia ^ aia &iMéiia ^ iMi - ^ - awt ^? fc-ta- catalytic, in the presence of a catalyst, which has the formula: AaMraNnXx0o where 0.25 < a < 0.98, 0.003 < m < 0.5, 0.003 < n < 0.5, 5 0.003 < x < 0.5 and o is dependent on the oxidation state of the elements, and A is at least one of Mo, Fe, Nb, Ta, Zr and Ru; M is at least one of V, Ce and Cr; N is at least one of Te, Bi, Sb and Se; and X is at least one of Nb, Ta, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B, In and Ce; in which the catalyst exhibits at least two crystal phases, one phase includes X-ray diffraction main crests at 22.1, 28.2, 36.2, 45.2, 50.5, 54.2, 55.4 and 58.5, and a second phase includes principal rays diffraction crests X in 22.1, 27.2, 35.3, 45.2 and 51.1. Figure 1 illustrates the X-ray diffraction (XRD) spectrum of main XRD ridges for catalysts 1-7. As used herein, the expression "(meth) acrylic acid" is intended to include both methacrylic acids as acrylic within your reach. In a similar manner, the expression of "(met) acplatos" attempts to include both * M * ,. ** > **? tllM *. ^ * .. r .-, t i. -.... * .., .-. *, - *., .. * - - -.-. ** .. **. m ^ - *. ^ .. methacrylates such as acrylates within their scope, and the expression of "met) acrolein" are intended to include both acrolein and methacrolein within their scope. As used herein, the term "(C3-C8) alkane" means an alkane, straight or branched chain, having from 3 to 8 carbon atoms per molecule of alkane. As used herein, the term "mixture" is understood to include within its scope, all forms of mixtures including, but not limited to, simple mixtures as well as combinations, alloys, etc. For the purposes of this application, the "% conversion" is equal to (moles of alkane consumed / moles of alkane supplied) x 100; "% selectivity equals (moles of desired carboxylic acid or unsaturated aldehyde, formed / moles of alkane consumed) x 100; and% yield "is equal to (moles of desired carboxylic acid or unsaturated aldehyde, formed / moles of alkane supplied) x (carbon number of the desired carboxylic acid or unsaturated aldehyde, formed / carbon number of the alkane supplied) x 100. For purposes of this application, "solution" means that more than 95 percent of the solid metal added to a solvent dissolves.It will be understood that the greater the amount of the solid metal not initially in solution, the poorer the performance of the derivative catalyst As mentioned above, a catalyst having at least two specific phases of crystals is described.The two phases of crystals can be obtained either through a specific method of catalyst preparation or by varying the composition of the catalyst. stage of the catalyst preparation method, a solution is formed by mixing the metal compounds, at least one of which contains or Xigen, and at least one solvent, in appropriate amounts, to form a solution. Generally, the metal compounds contain the elements A, M, N, X and 0. In one embodiment, A is at least one of the elements Mo,, Fe, Nb, Ta, Zr and Ru; M is at least one of the elements V, Ce and Cr; N is at least one of the elements Te, Bi, Sb and Se; and X is at least one of the elements Nb, Ta, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb,. Bi, B, In and Ce. In a preferred embodiment, A is at least one of the Elements Mo and; M is at least one of V, Ce and Cr; N is at least one of Te, Bi and Sb; and X is at *. ** *,. *. ** * ¿**. ** .. minus one of Nb, Ta and Zr. In a preferred embodiment, A is Mo, M is V, N is Te and X is Nb. Suitable solvents include water, alcohols include, but are not limited to, methanol, ethanol, propanol, and diols, etc., as well as other polar solvents known in the art. In general, water is preferred. Water is any water suitable for use in chemical synthesis, including, without limitation, distilled water and deionized water. The amount of water The present is that amount sufficient to keep the elements substantially in solution for a sufficient period, to avoid or minimize segregation of the composition and / or phase, during the preparation stages. Therefore, the amount of water will vary from according to the amounts and the solubility of the combined materials. However, as noted above, the amount of water must be sufficient to ensure an aqueous solution and not an aqueous paste at the time of mixing. Once the aqueous solution is formed, the water is removed by the combination of any suitable method known in the art to form a precursor of the ^ j ^^^ S j * ^^ catalyst. These methods include, without limitation, vacuum drying, freeze drying, spray drying, rotary evaporation and air drying. Vacuum drying is generally carried out at pressures ranging from 10 to 500 mm / Hg. Freeze drying typically leads to freezing of the solution, using, for example, liquid nitrogen, and drying the frozen solution under vacuum. Spray drying is generally carried out under an inert atmosphere, such as nitrogen, argon or air, with an inlet temperature ranging from 125 to 200 ° C and an outlet temperature ranging from 75 to 150 ° C. Rotary evaporation is generally carried out at a bath temperature of 25 to 90 ° C and a pressure of 10 to 760 mm / Hg, preferably at a bath temperature of 40 to 90 ° C and a pressure of 10 to 350 mm / Hg. , more preferably 40 to 60 ° C and a pressure of 10 to 40 mm / Hg. Air drying can occur at temperatures ranging from 10 to 90 ° C. Rotary evaporation or air drying are generally preferred. Once obtained, the catalytic precursor is calcined under an inert atmosphere. This inert atmosphere can be of any material that is substantially ~ * ^ - ^. ^ * - l ^ * ^ ¿j ¿** inert, that is, do not react or interact with the catalyst precursor. Suitable examples include, without limitation, nitrogen argon, xenon, helium, or mixtures thereof. Preferably, the inert atmosphere is argon or nitrogen, more preferably argon. The inert atmosphere may flow over the surface of the catalytic precursor or may not flow (a static environment). It is important to understand that an atmosphere without flow means that the inert gas is not allowed to flow over the surface of the catalytic precursor. It is preferred that the inert atmosphere does not flow over the surface of the catalytic precursor. However, when the inert atmosphere does not flow over the surface of the catalytic precursor, the flow rate can vary over a wide range, for example to a space velocity from 1 to 500 hr "1. Calcination is typically done at a temperature of 350 to 850 ° C, preferably 400 to 700 ° C, more preferably 500 to 640 ° C. adequate amount of time, to form the catalyst. In one embodiment, the calcination is carried out in 0.5 to 30 hours, preferably 1 to 25 hours, more preferably 1 to 15 hours. • - ^ ---- * "* • -áaa¿A --_ í_t ^ -toßl With the calcination, a catalyst is formed, which has the formula AaMmNnXx0o where A, M, N and X have the above definitions. The 5 molar ratios, a, m, n and x are typically 0.25 < a < 0.98, 0.003 < m < 0.5, 0.003 < n < 0.5, 0.003 < x < 0.5; preferably 0.35 < a < 0.87m 0.045 < m < 0.37, 0.020 < n < 0.27 and 0.005 < x < 0.35. The catalyst prepared will exhibit at least two phases of crystals, one phase includes major X-ray diffraction ridges at 22.1, 28.2, 36.2, 45.2, 50.5, 54.2, 55.4, and 58.5, and a second phase includes X-ray diffraction principal crests at 22.1, 27.2, 35.3, 45.2, and 51.1. The second ase also includes X-ray diffraction ridges in 7.9, 9.1 and 29.2. Such major crests and ridges are more fully defined in Table 1 (XRD crests of Phase A) and Table 2 (XRD crests of Phase B) below.

Table 1 twenty Table 2 The molar ratio "o", that is, the amount of oxygen (0) present, is dependent on the oxidation state of the other elements in the catalyst. However, typically "o" is from 3 to 4.7,. based on the other elements present in the catalyst. When the composition of the catalyst varies outside the ranges defined above, the catalyst will not exhibit both phases of X-ray diffraction. The catalyst of this invention can be used as a solid catalyst alone or can be used with a suitable support, such as , without limitation, silica, alumina, titania, aluminosilicate, diatomaceous earth or zirconia. The configuration of the catalyst can be of any suitable configuration and will depend on the application of the catalyst. In a similar manner, the particle size of the catalyst can be any suitable particle size, depending on the particular use of the catalyst.

In a second aspect of the present invention, a process for preparing aldehydes and saturated acids, including subjecting an alkane to catalytic oxidation, is provided in the presence of the catalyst described above. The starting materials for this process are generally one or more alkane gases and at least one gas containing oxygen. It is preferred that the starting materials also include water vapor. Therefore, a gas from a starting material is supplied to the system, which includes a gas mixture of at least one alkane and water vapor. This at least one gas containing oxygen can be included in this mixture or can be supplied separately. Also, the dilution gas, such as an inert gas, includes, without limitation, nitrogen, argon, helium, water vapor or carbon dioxide. The dilution gas can be used to dilute the starting material and / or adjust the space velocity, the partial pressure of the oxygen and the partial pressure of the water vapor. Suitable molar ratios of the alkane / oxygen / dilution gas / water in the gas mixture of the starting material are known in the art, as is the charge ratio of the alkane / air / water vapor. By example, suitable ranges are presented in the US patent. , No. 5, 380, 933. The alkane, starting material, is generally any alkane suitable for the oxidation of gas phase in an aldehyde or unsaturated acid. Generally, the alkane is a C3-C8 alkane, preferably propane, isobutane or n-butane, more preferably propane or isobutane, and especially preferred is propane. Also, in another embodiment, the alkane can be a mixture of alkanes, which include the C3-C8 alkanes, as do the lower alkanes, such as methane and ethane. This at least one gas containing used oxygen, can be a pure oxygen gas, a gas containing oxygen, such as air, a gas enriched with oxygen, or mixtures thereof. In a preferred embodiment, the starting material is a gas mixture of propane, air and water vapor. The mixture of the starting gas is subjected to catalytic oxidation, in the presence of the catalyst of the present invention. The catalyst may be in a fluidized bed reactor or in a fixed bed. The reaction is usually conducted under atmospheric pressure, but may be * M ** ^^ ** ma * driven under high or reduced pressure. The reaction temperature is generally 200 to 550 ° C, preferably 300 to 480 ° C, more preferably 350 to 440 ° C. The space velocity of the gas is generally from 100 to 10,000 hr "1, preferably from 300 to 6,000 hr" 1, more preferably from 300 to 3,000 hr? . Likewise, in the method of the present invention, it will be understood that an unsaturated aldehyde can also be formed. For example, when propane is the starting alkane, acrolein can be formed, and when isobutane is the starting alkane, methacrolein can be formed. In a third aspect of the present invention, a process for preparing aldehydes and saturated acids is provided, which includes subjecting a compound, selected from propylene, acrolein and isopropanol, to a catalytic oxidation, in the presence of the catalyst described above. The process is carried out in the same manner described above for the conversion of alkanes to aldehydes or unsaturated acids, except that the alkane is replaced by propylene, acrolein or isopropanol. Likewise, the reaction temperature is generally 150 to 500 ° C. For propylene and isopropanol, the reaction temperature is preferably 250 to 400 ° C and for acrolein, it is preferably 180 to 350 ° C. The space velocity of the gas is generally 100 to 10,000 hr "1, preferably 5 300 to 6,000 hr 1. The abbreviations used in this application are: ° C = degrees centigrade mm = mm Hg = mercury g = grams cm = centimeters mole = millimoles 10% = weight percent N2 = nitrogen ml / m = milliliters per minute The following examples illustrate the process of the present invention Based on the amount of the starting material used, there is no segregation of the composition nor Also, no loss of certain elements during the preparation stages, all samples of the catalyst were prepared as follows, when they have an empirical formula of MOjVg Te0 23Nb0.08-0.120n, where n was determined by the oxidation state of the other elements . The solutions or pastes Aqueous compounds containing the desired metal elements were prepared by heating the appropriate compounds in water, at a temperature ranging from 25 to 95 ° C. Whenever - ^^ ** * t * te * * í ** * *. . - ...,. ». ** .. ** -_. , .. r .. * * * * **. - * - *. ********* necessary, the aqueous solutions or pastes were cooled to temperatures ranging from 25 to 60 ° C. The water was then removed from the aqueous solutions or pastes by the appropriate drying method, at pressures ranging from 760 to 10 mm / Hq.

Example 1 A catalyst-1 was prepared with the empirical formula of Mo1Vo.3Teo.23Nb0 10, as follows. IN a flask, which contains 420 g of water, 25.8 g of ammonium heptamolybdate tetrahydrate (Aldrich, Chemical Company), 5.1 g of ammonium metavanadate (Aldrich, Chemical Company) and 7.7 g of telluric acid (Aldrich Chemical Company) were dissolved, on heating at 80 ° C. After cooling to 40 ° C, mixed 121.2 g of an aqueous solution of niobium oxalate (Reference Metals Company), containing 17.3 mmoles of niobium, to obtain a solution. The water in this solution was removed by means of a rotary evaporator, with a hot water bath, at 50 ° C and at 28 mm / Hg, to obtain 46 g of a solid catalyst precursor. Twenty grams of the solid catalyst precursor was calcined in a covered crucible, previously purged with m m átí M? ^. *** ^ * ^. *. **. r * ¿A > ± »i ^^ á» l_J-ifc --_ argon, in an environment without flow, at 600 ° C, for 2 hours. The oven had previously been heated to 200 ° C and remained so for one hour, then gradually rose to 600 ° C. During the calcination, the covered crucible was inside a covered laboratory cuvette, with an Ar space velocity of 57 hr "1. Due to the covered crucible, the argon did not flow on the surface of the precursor, but rather served to ensure that the atmosphere outside the crucible remained argon.The atmosphere inside the crucible was argon and the gases escaped from the catalyst. The catalyst, thus obtained, was ground into a fine powder and pressed into a mold and then ground and sieved into granules of 10 to 20 mesh. The catalyst (13.4 g) was packed in a reactor.

U-tube, stainless steel, with internal diameter of 1.1 cm, for the oxidation of propane in the gas phase. The oxidation was carried out with a temperature of the reactor bath (molten salt) of 390 ° C, a propane / air / water vapor charge ratio of 1/15/14 and a speed Spatial of 1,200 hr "1. The reactor effluent was condensed to separate the liquid phase (the condensable material) and the gas phase.This phase of gas was analyzed by the Gas chromatography ("GC") to determine the conversion of propane. The liquid phase was also analyzed by GC for the yield of acrylic acid. The oxidation results are presented in Table 4. The catalyst was also analyzed by X-ray diffraction to determine its crystalline structure. The principal diffraction angles and corresponding relative intensities are shown in Table 3 and in Figure 1.

Example 2 A catalyst 2 was prepared, with the empirical formula of MoAo 32Teo 23NA os and was tested in the same manner as described in Example 1. The results of the oxidation are shown in Table 4. The main angles 15 of the diffraction and the corresponding relative intensities are shown in Table 3 and in Figure 1.

Example 3 A catalyst 3 was prepared, with the formula Empirical of MoAo 3Teo 2Nfro n and tested in the same manner as described in Example 1. The results of the oxidation are shown in Table 4. The main angles of the diffraction and the corresponding relative intensities are shown in Table 3 and in Figure 1.

Comparative Example 1 A catalyst 4 was prepared with the empirical formula of MoAo 2oTeo 4oNA 05 and tested in the same manner as described in Example 1. The oxidation results are shown in Table 4. The main angles of the diffraction and the corresponding relative intensities are shown in Table 3 and Figure 1.

Comparative Example 2 A catalyst 5 was prepared, with the empirical formula of Mo-, V031Te-or 46Nb0 13, and was tested in the same manner as described in Example 1. The results of the oxidation are shown in Table 4. The principal angles of the diffraction and the corresponding relative intensities are shown in Table 3 and in Figure 1.

Comparative Example 3 A catalyst 6 was prepared, with the empirical formula of MOjV ,, S0Te050Nb0 06, and was tested in the same way as described in Example 1. The oxidation results are shown in Table 4. The main angles of the diffraction and the corresponding relative intensities are shown in Table 3 and in Figure 1.

Comparative Example 4 A catalyst-7 was prepared, with the empirical formula of MoAo 3Te023Nb0 10, as follows. Into a flask, containing 400 g of water, 18.4 g of ammonium heptamolybdate tetrahydrate (Aldrich, Chemical Company), 3.7 g of ammonium metavanadate (Aldrich, Chemical Company) and 5.5 g of telluric acid (Aldrich Chemical Company) were dissolved. ), when heating to 80 ° C. After cooling to 40 ° C, 75.5 g of an aqueous solution of niobium oxalate (Metals Company Reference), containing 8.0 mmoles of niobium, were mixed to obtain a solution. The solution was dried in the same manner as described in Example 1, to obtain a catalyst precursor. This precursor of the catalyst was pre-treated with air at 315 ° C for 180 minutes, before calcining and pressed into granules in the same manner as described in Example 1. wk-á_-b ^ dí - i-? One gram of the catalyst was packed in a quartz tube reactor with an internal diameter of 3.8 mm for the oxidation of the gas phase propane. Oxidation was conducted with a reactor bath temperature of 380 ° C, a propane / air / water vapor charge ratio of 1/96/3, and a space velocity of 1,200 hr "1. The reactor effluent it was analyzed by the infrared (IR) spectrum to determine the propane conversion and the AA yield The oxidation results are shown in Table 10 4. The main diffraction angles and the corresponding relative intensities are shown in Table 3 and in Figure 1.

Table 3 fifteen MMtMriatlMtottibuii *. *. ** ^ * - ** The above data shows that both phases of X-ray diffraction are present in the catalyst, when this catalyst is prepared by the method described above and within the ranges of composition 5 described above. The catalyst does not exhibit both phases of X-ray diffraction when prepared by a different method or when the composition is outside the ranges described above.

*? M ¡mm l ^ tebM IM-.

Table 4 Comp. = comparative (%) of Conv. = percentage of converted propane (%) of selec. = selectivity of the conversion of propane to acrylic acid in percent (%) yield = the yield of acrylic acid in percent. The above data demonstrate that the catalyst is efficient in converting propane to acrylic acid, when the catalyst contains both phases of X-ray diffraction. The catalyst is not effective when only catalyst present in one of the X-ray diffraction phases. Example 4 Catalyst 2 was tested in oxidation, as in Example 1, except that propane was replaced with propylene. Oxidation was conducted with a reactor bath temperature (molten salt) of 350 ° C, a propylene / air / water vapor / nitrogen charge ratio of 1/35/10/2.8, and a space velocity of 3,600 hr. "1. The The reactor effluent was condensed to separate the liquid phase (the condensable material) and the gas phase. This gas phase was analyzed by gas chromatography ("GC") to determine the conversion of propylene. The liquid phase was also analyzed by the GC for the acid yield acrylic. The results of the oxidation are shown in Table 5.

Comparative Example 5 Catalyst 4 was tested in the same manner as described in Example 4. Oxidation results are shown in Table 5.

Comparative Example 6 Catalyst 8, with the empirical formula of M?., V0 iTe023Nb010, was prepared from the same starting material, as described in Example 4. A solution containing 5.39.5 g of heptamolybdate ammonium tetrahydrate, 7.85 g of ammonium metavanadate and 11.8 g of telluric acid and a solution of ammonium niobium oxalate, containing 27.7 mmoles of niobium, was prepared in the same manner as that described in Example 1. This solution was frozen to a Solid form in a bath of acetone and dry ice, and dried under vacuum, to obtain 64 g of acid of the solid powder. The powdered catalyst precursor was pressed and sized to granules and then calcined at 600 ° C for two hours, with a stable nitrogen flow. The resulting catalyst (42 g) was pressed and sized into granules. This catalyst (23 g) was tested in the same manner as described in Example 4, except that a reactor bath temperature of 390 ° C and a propylene / air / water vapor charge composition was used. with a volume ratio of 1/15/14. The results of the oxidation are shown in Table 5. im-Mii? ÉÉtfimtirhtipr - - • - - "" - Table 5 (%) of Conv. = percent of converted propylene. Temp .. = temperature (%) of selc. = selectivity of the conversion of propylene to acrylic acid in percent (%) yield = the yield of acrylic acid in percent Comp. = Comparative 10- The above data shows that the catalyst is more efficient to convert propylene to acrylic acid, when this catalyst contains both phases of diffraction of X-aids. The catalyst is less effective when only one phase of X-ray diffraction is present 15 on the catalyst.

Example 5 *? mftMlntat *, *? i *? * 1 ** ^ - **. *. ? . - ,, **. *. * ... -. ^. ^^ -. ^ ..., *. ......., *! *! *. * .. - * - * '< - • - Catalyst 2 was tested in oxidation as in Example 1, except that propane was replaced with isopropanol. Oxidation was conducted with a reactor bath temperature (molten salt) of 350 ° C, a charge ratio of isopropanol / air / water vapor / nitrogen of 1/35/10/2 2.8 and a space velocity of 3,600 hr. "1. The reactor effluent was condensed to separate the liquid phase (the condensable material) and the gas phase.This gas phase was analyzed by gas chromatography (" GC ") 10 to determine the conversion of isopropanol. The liquid phase was also analyzed by the GC for the performance of acrylic acid.The results of the oxidation are shown in Table 6.

Comparative Examples 7 and 8 Catalyst 4 was tested in the same manner as described in Example 5, except that the temperatures of the reactor bath were both 320 and 390 ° C and the charge composition of isopropanol / air / water vapor 20 in volume ratio was 1/15/14. The results of the oxidation are shown in Table 6. ? * k * ¿l **? .i i *. . -. »? , .. > . > -.-. -..- .... .. .t *. * i.i. .Jj-l-U -au. ^ Table 6 (%) of Conv. = percent of converted propylene. Temp .. = temperature 5 (%) of selc. = selectivity of the conversion of propylene to acrylic acid in percent (%) yield = the yield of acrylic acid in percent. Comp. = Comparative 10 The above data demonstrates that the catalyst is more efficient to convert isopropanol to acrylic acid, when this catalyst contains both phases of diffraction of X-aids. The catalyst is less effective when only one phase of X-ray diffraction is present. in the catalyst.

Example 6 '~ ^ * «- = * > i ----...- J. -, t .. i. * - **** > ** - * ******* • ».. -te--, ii - .vH ** * .- Catalyst 2 was tested in oxidation as in Example 1, except that the propane was replaced with Acrolein Oxidation was conducted with a reactor bath temperature (molten salt) of 251 ° C, an acrolein / air / water vapor / ratio of 1.7 / 52/47, and a space velocity of 3,600 hr x. The effluent from the reactor was condensed to separate the liquid phase (the condensable material) and the gas phase. This gas phase was analyzed by gas chromatography ("GC") to determine the conversion of acrolein. The liquid phase was also analyzed by GC for the yield of acrylic acid. The results of the oxidation are shown in Table 7.

Example 7 Catalyst 2 was tested in the oxidation as in Example 6, except that the oxidation was conducted at a reactor bath temperature (molten salt) of 220 ° C. The results of the oxidation are shown in Table 7.

Comparative Examples 9 and 10 Catalyst 4 and catalyst 8 were tested in the same manner as described in Example 6, except that the temperatures of the reactor bath were both 251 and 250 ° C, respectively, and the charge composition of the Acrolein / air / water vapor in volume ratio was 1/15/14. The results of the oxidation are shown in Table 6.

Table 7 (%) of Conv. = percent of converted propylene. Temp .. = temperature (%) of selc. = selectivity of the conversion of propylene to acrylic acid in percent (%) yield = the yield of acrylic acid in percent. Comp. = Comparative The above data demonstrate that the catalyst is more efficient to convert isopropanol to acrylic acid, when this catalyst contains both phases of X-ray diffraction. The catalyst is less effective when only one phase of X-ray diffraction is present in the catalyst. ! ^ g *? a ii i? tl? i ?? áls? *? **** t ** aá **? ** ^ **. I 11 Ü l ¡11 ill II

Claims (14)

1. CLAIMS 1. A catalyst, which has the formula AaMraNnXx0o where 0.25 < a < 0.98, 0.003 < m < 0.5, 0.003 < n < 0.5, 0.003 < x 0.5 and o is dependent on the oxidation state of the elements, and A is at least one of the Mo,, Fe, Nb, Ta, Zr and Ru; M is at least one of V, Ce and Cr; N is at least one of Te, Bi, Sb and Se; and X is at least one of Nb, Ta, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B, In, and Ce; in which the catalyst exhibits at least two crystal phases, one phase includes X-ray diffraction main crests at 22.1, 28.2, 36.2, 45.2, 50.5, 54.2, 55.4 and 58.5, and a second phase includes principal rays diffraction crests X in 22.1, 27.2, 35.3, 45.2 and 51.1.
2. 2. The catalyst, according to claim 1, wherein this catalyst comprises 0.35 < a < 0.87, 0.045 < m < 0.37, 0.020 < n < 0.27 and 0.005 < x < 0.35.
3. 3. The catalyst, according to claim 1, wherein A is at least one of the elements Mo and W; M is at least one of V, Ce and Cr; N is at least one of Te, Bi and Sb; and X is at least one of Nb, Ta and Zr.
4. 4. The catalyst, according to claim 1, wherein A is Mo, M is V, N is Te, and X is 5 Nb.
5. 5. The catalyst, according to claim 1, wherein the second phase further comprises X-ray diffraction ridges in 7.9, 9.1 and 29.2
6. 6. A process for preparing aldehydes and unsaturated acids, comprising subjecting an alkane to a catalytic oxidation, in the presence of the catalyst of claim 1.
7. 7. The process, according to claim 6, wherein the alkane is propane and the unsaturated aldehyde is 15 the acrolein.
8. 8. The process, according to claim 1, wherein the alkane is propane and the unsaturated acid is acrylic acid.
9. 9. The process for preparing aldehydes and saturated acids, which comprises subjecting a compound, The selected catalyst of propylene, acrolein and isopropanol, to catalytic oxidation, in the presence of the catalyst of claim 1.
10. 10. The process, according to claim 5 9, wherein the compound is propylene and the unsaturated aldehyde is acrolein.
11. 11. The process, according to claim 9, wherein the compound is propylene and the unsaturated acid is acrylic acid.
12. 12. The process according to claim 9, wherein the compound is acrolein and the unsaturated acid is acrylic acid.
13. 13. The process, according to claim 9, wherein the compound is isopropanol and the aldehyde 15 unsaturated is acrolein.
14. 14. The process, according to claim 9, wherein the compound is isopropanol and the msaturado acid is acrylic acid. ikBiaiHMÍIiaMMtttiii-ft-fcrita¡ ^ - y ^^^