FR2693384A1 - Catalyst for oxidn. of cyclic or acyclic alkane(s) to alkene(s), unsatd. aldehydes and acids - comprises nickel molybdate opt. impregnated with ammonium phosphate and mixed with tellurium molybdate, esp. for industrial scale conversion of propane to propylene, acrolein and acrylic acid - Google Patents

Abstract

The catalyst for oxidn. of alkanes into alkenes and the corresp. ethylenically unsatd. aldehydes and carboxylic acids, has the formula: (NiO)x.(MoO3)y.(Te2MoO7)z.(P2O5)t (I); x,y,z and t are the respective percentages (by wt.) of the active agents, Ni, Mo, Te and P, and (x+y) = 0.1-15%, z = 0-10%, (0.1-10%) t = 0-10% and y/x = 1.2-9. Pref., the catalyst has a specific surface of 20-50 m2/g and an ave. particle size of 0.1-5mm. The catalyst is unsupported or mixed with a diluent or a solid or inert support. Pref., the alkane is contacted with O2(-contg. gas) in a mol. ratio alkane to O2 of 0.1-30, in the catalyst at 400-700 deg.C and 0.5-10 bars, e.g., for an apparent contact time of 0.01-30 s. The catalysts are prepd. by (i) preparing a first powdered precursor comprising a Ni molybdate of formula (NiO)x.(MoO3)y (II) from an aq. soln. of Ni nitrate and an aq. soln. of molybdic acid; (ii) opt. preparing a second powdered precursor comprising Te molybdate of formula Te2MoO7 (III) from an aq. soln. of ammonium paramolybdate and an aq. soln. of telluric acid; (iii) impregnating the precursor (II) with an aq. soln. of (NH4)2HPO4 to obtain a powdered impregnated precursor of formula (NiO)x.(MoO3)y.(P2O5)t (IV) and (iv) homogeneously mixing calculated amts. of the precursors (IV) and (III) to form the required catalyst (NiO)x.(MoO3)y.(Te2MoO7)z.(P2O5)t (I). The precursor (II) and/or the precursor (III) and/or the impregnated precursor (IV) and/or the final catalyst (I) may each be thermally treated at 200-700 deg.C for 15 mins. - 24 hrs. The catalyst is activated by a thermal treatment comprising raising the catalyst temp. stagewise to the alkane oxidn. temp. in the oxidn. reactor and maintaining it at the temp. for 5 mins. - 10 hrs. before introducing the reaction mixt. into the reactor. USE/ADVANTAGE - The catalysts are useful for oxidn. of 2-20C opt. cyclic alkanes into alkenes and the corresp. unsatd. aldehydes and carboxylic acids, esp. for industrial scale conversion of propane into a mixt. of propylene, acrolein and acrylic acid and conversion of isobutane into a mixt. of isobutene, methacrolein and methacrylic acid. The catalysts give controlled and selective oxidn. of alkenes in the gas phase at elevated temps. to pref. ethylenically unsatd. prods. without excessive conversion into total oxidn. prods., e.g., CO, CO2 and H2O.

Description

CATALYST AND METHOD OF OXIDATION, HOUSEHOLD AND SELECTIVE
On aLKANES
The present invention provides a mild and selective oxidation catalyst for alkanes to obtain the corresponding alkenes and ethylenically unsaturated aldehydes and carboxylic acids; on a method of manufacturing said catalyst; as well as on the corresponding catalytic oxidation process, wherein said catalyst is used.

 Examples of such alkane oxidation reactions, which are currently of great industrial importance, are the selective oxidation of propane to a mixture of propene, acrolein and acrylic acid, as well as oxidation of isobutane to a mixture of isobutene, methacrolein and methacrylic acid.

He is known, particularly by French patents
FR-A-2 093 773 and FR-A-2 222 349, that propane and acrolein can not be selectively oxidized to acrylic acid, and that, in the same way, isobutene and methacrolein can be oxidized into methacrylic acid. The fact of obtaining these intermediates from propane and isobutane, respectively, with good selectivity, makes it possible to develop complete processes for the production of acrylic acid from propane and methacrylic acid from 1 isobutane.

The literature has already reported various propane oxidation catalysts acrolein and acrylic acid. For example, in the article of
YC KIM, W. UEDA and Y. MORO-OKA "New Developments in
Selective Oxidation, Preprints - University of Bologna (Italy), 1989 ", and in Japanese Patent JP 02/83348 are described silver-doped bismuth vanad-molybdate catalysts, which have been shown to be active for ammoxidation of propane in acrylonitrile and for the oxidation of propane to acrolein (conversion: 13% selectivity: 63.5%) One can also mention the oxidation of propane on boron phosphate type catalysts (Japanese Patent JP 02 / 67,236), on doped or non-doped tellurium-molybdates doped with cadmium halides: GIORDANO, JCJ BART, P. VITARELLI and S.CAVALLARO,
Oxidation Communications 7, 99-111 (1984) J, and on catalysts of the SbPMoO type (US Pat. No. 4,260,822).

 As regards the catalytic oxidation of isobutane, it is possible to mention the use of catalysts of the Mo, P and V type heteropolyanion type, described in European Patent Applications EP-A-425 666 and EP-A -418 657, which, for isobutane conversion rates of about 10%, make it possible to obtain selectivities in methacrolein of 15t-16t and selectivities in methacrylic acid of the order of 55% -56%.

 The object of the present invention is to provide a catalyst capable of selectively oxidizing, in the gas phase and in the presence of oxygen, various alkanes, more particularly propane and isobutane, into controlled oxidation products, avoiding a significant conversion to total oxidation products, such as CO, CO2 and H20.

The subject of the present invention is therefore firstly a controlled and selective oxidation catalyst for alkanes to the corresponding alkenes and aldehydes and carboxylic acids with ethylenic unsaturation, characterized in that it corresponds to the formula
(NiO) x '(MoO3) y (Te2MoO7) z. (P205) t wherein x, y, z and t represent the mass percentages in the active mass of the respective active ingredients, namely Ni, Mo, Te and P, and satisfy the following relationships
0.1% <x + y <15% 0% O% # z <10;
0% <t <10%; and
1,2 <y / x <9
In particular, z satisfies the following relationship 0.1% <z <10 t.

 The specific surface of the catalysts according to the invention is generally between 20 and 50 m 2 / g, while the average particle size is generally between 0.1 and 5 mm approximately (particle size between 50 and 2500 mesh).

 The catalysts according to the present invention can be used in bulk form, that is to say in the unsupported state. They can also be used in the form of a mixture with a solid or inert diluent or support, such as silicon carbide, which makes it possible to prevent hot spots from being created in certain zones of the catalytic bed. In the case of a supported catalyst, the mass percentages x, y, z and t are independent of the amount of support used.

The present invention also relates to a method of manufacturing the catalyst as defined above, characterized in that it comprises
the preparation of a first powdery precursor
consisting of a nickel molybdate of general formula
(NiO) x (MoO3) y, from an aqueous solution of
nickel nitrate and an aqueous acid solution
molybdic; with, as the case may be
the preparation of a second powdery precursor
consisting of a tellurium molybdate of formula
Te2MoO7, from an aqueous solution of
ammonium paramolybdate and an aqueous solution
of telluric acid
impregnation of said first precursor with a solution
aqueous (NH4) 2HPO4 to obtain a precursor
impregnated with a general formula
(NiO) x (MOO3) y (P205) t; and
the homogeneous mixture of said impregnated precursor
powder and said second powder precursor for
obtain the desired catalyst (NiO) x (MOO3) y (Te2MoO7). (P205) t, the choice of the relative quantities of starting constituents and process parameters, such as pH, precipitation temperature, concentration, filtration temperature, temperature and drying time, as is well known to those skilled in the art.

 In a particularly preferred embodiment of the process for preparing the catalysts according to the invention, there is provided a heat treatment of the first powder precursor and / or the second powder precursor and / or the first impregnated powder precursor and / or the final catalyst, each heat treatment being conducted at a temperature generally between 200 and 700 ° C for a period of between 15 minutes and 24 hours.

 It is also recommended to carry out a final step of thermal activation of the catalyst according to the invention, this step of bringing said catalyst, stepwise, under a nitrogen-oxygen mixture, to the operating temperature of the controlled oxidation and alkane, in the oxidation reactor, and to maintain the catalyst at this temperature for a period of time of between 5 minutes and 10 hours, in particular between 15 minutes and 1 hour, before introducing the reaction mixture into said oxidation reactor.

 The present invention also relates to a controlled and selective oxidation process of a linear, branched or cyclic alkane containing from 2 to 20 carbon atoms, in particular propane and isobutane, leading to the alkene as well as to the corresponding aldehyde and the corresponding carboxylic acid, comprising contacting said alkane with molecular oxygen or a molecular oxygen-containing gas, at a temperature in particular between 400 ° C and 700 ° C at a pressure in particular of between 0.5 and 10 bar and in the presence of a catalyst, characterized in that a catalyst as defined above is used.

 The oxidation is conducted with an apparent contact time, i.e., a ratio between the reaction volume and the incoming gas flow rate calculated under normal conditions of temperature and pressure, which is between 0.01 and 30 seconds, and preferably between 0.1 and 5 seconds, while the molar ratio between alkane and oxygen is generally between 0.1 and 30, and preferably between 0.1 and 10. .

 Moreover, in known manner, the reaction mixture can be diluted with an inert gas, such as nitrogen, carbon dioxide, water vapor, etc.

 The oxidation process according to the invention may be carried out in a conventional catalytic gas phase oxidation reactor, such as a fixed bed reactor or a fluidized bed reactor.

 The specific examples given below describe the preparation of catalysts according to the invention, as well as the oxidation process of propane and isobutane using these catalysts. These examples are given for information only and not limiting.

In the examples, the catalysts according to the invention are generally designated by
A + b% B + c% C, where A = (NiO) x (MoO3) y
B = Te2MoO7 or 2TeO2, MoO3
C = P205
b is z
c is t
b and c represent mass% in the total mass
oxides
Example 1
Preparation of catalysts A1 + b% B + c% C with v / x = 1.5
in A1
First stage
Preparation of Aj
In a first step, two solutions were prepared separately: the first from 133.04 g of nickel nitrate hexahydrate in 2000 cm3 of distilled water (0.23 mol / liter) at a temperature of 85 ° C and a pH 4.9, the second, of the same molarity, from 74.04 g of H2MoO4 in 2000 cm3 of an ammoniacal solution at a temperature of 85 ° C and a pH of 5.6.

 The nickel nitrate solution was then poured into the molybdic acid solution with stirring to precipitate the nickel molybdate. The starting pH of the mixture was 5.2 and the precipitation temperature was maintained at 85 ° C. The total time of the precipitation was 80 minutes, and the resulting precipitate was yellow in color.

 To obtain the amount of over-stoichiometric molybdenum relative to nickel, the temperature of the solution containing the precipitate was lowered to 65 ° C and filtered while maintaining this temperature.

 The precipitate obtained was washed extensively with distilled water and then dried in an oven at 120 ° C. for 2 hours The mass of product obtained was 48.3 g with y / x = 1.5.

 After drying, the product was air-stripped in a muffle furnace at 550 ° C for 2 hours, then cooled to room temperature and stored in a desiccator. The specific product after treatment was 27.2 m2 / g.

Second step
Preparation of B
The tellurium molybdate was prepared from 11.346 g of ammonium paramolybdate and 29.75 g of telluric acid H6TeO6. The two salts were dissolved with stirring in a minimum of distilled water. It was then heated slowly to boiling to concentrate the solution which became increasingly yellow and more and more viscous.

It was concentrated to a paste which was then dried in an oven at 120 ° C. to give a powder which, after light grinding, was calcined at 47 ° C. The Te 2 MoO 4 tellurium molybdate obtained was characterized by X-ray diffraction measurements, infrared spectroscopy and BET surface area determination, which was 1 m 2 / g.

Third step
Impregnation of (NiO) x. (MoO3) y. by (NHL2HPoxl
0.0918 g of (NH4) 2HPO4 were dissolved with stirring in a minimum of distilled water, and this solution was added to 5 g of (NiO) x (M0O3) y obtained in the first step, heated to 300 ° C. under vacuum. When the addition was complete, it was brought back to atmospheric pressure and the product was dried under a stream of argon at 200 ° C. When the impregnating product was dry, it was calcined in the air at 500 C.

Fourth stage
Preparation of a catalyst of the title
A tellurium molybdate dispersion was prepared
Te2MoO7 in the silicon carbide corresponding to 0.5 g of catalyst per 10 g of silicon carbide. To this dispersion, the corresponding quantity of the impregnating product of the third stage was then intimately mixed until a homogeneous mixture having an average particle size of about 0 was obtained. 15 mm (100 mess).

 For some catalysts, the impregnation step was not conducted (c = 0).

Example 2
Preparation of catalysts A2 + b% B + c? C with v / x = 2.8
in A2
The procedure is as in Example 1 while conducting the first step as follows
Two solutions were prepared separately: the first from 218.1 g of nickel nitrate hexahydrate in 1500 cm3 of distilled water (0.5 mole / liter) at a temperature of 70 ° C and a pH of 4.9 the second, of the same molarity, from 121.5 g of H2MoO4 in 1500 cm3 of an ammoniacal solution at a temperature of 70 ° C and a pH of 5.75.

 The nickel nitrate solution was poured into the 70% molybdic acid solution with stirring to precipitate the molybdate, and 25 minutes after the start of precipitation the temperature of the solution containing the precipitate was lowered to 25%. C.

 When the precipitation was complete, the resulting precipitate was filtered and washed extensively with distilled water. It was then dried in an oven at 1200 ° C. for 2 hours. The mass of product obtained was 102.3 g with y / x = 2.8.

 After drying, the product was subjected to a heat treatment in a muffle furnace, as at the end of the first step of Example 1. The value of the specific surface area of A2 after the heat treatment was 21.2 m 2 / g.

Examples 3 to 20
Catalytic Oxidation of Propane on Catalysts of
Example 1
A sample of 0.5 g of a catalyst studied was diluted in approximately 10 g of silicon carbide, then introduced into a total volume quartz tube reactor = 30 cm3 (internal diameter: 1 cm), connected to three flowmeters mass fed respectively with nitrogen, oxygen and propane. Prior to the catalytic oxidation reaction, the catalyst was further processed by calcining in the reactor under a nitrogen-oxygen mixture. To do this, the temperature was increased in steps to the operating temperature T ("C) and this temperature was maintained for 30 minutes. After this operation, the starting gaseous reactant mixture having the following composition: 15% of propane, 17.85% of oxygen and 67.15% of nitrogen (t by volume) The flow rate used is D (l / h), and the pressure of 1.2 bar.

 The products obtained during the reaction were analyzed online by gas chromatography (TCD and FID).

 The results corresponding to a series of tests are given in the following Table I, these results having been obtained in the stationary state after several days of operation.

Table I: Light Oxidation of Propane on Catalysts of Type A1 + b% B + c% C

Ex. <SEP> Catalysts <SEP> H2O / Propane <SEP> D <SEP> T <SEP> Conversion <SEP> Sétectivité ** <SEP> (%)
<tb> (report <SEP> (l / h) <SEP> (C) <SEP> *
<tb> molar) <SEP> (%) <SEP> CO <SEP> CO2 <SEP> Ethylene <SEP> Propene <SEP> Acetaldehyde <SEP> Acrolein <SEP> Acid
<tb> acrylic
<tb> 3 <SEP> A1 <SEP> + <SEP> 0.5% B <SEP> 0 <SEP> 5 <SEP> 450 <SEP> 9.9 <SEP> 21.8 <SEP> 16.3 <SEP> 0.4 <SEP> 24.4 <SEP> 0.67 <SEP> 13 <SEP> 23
<tb> 4 <SEP>"<SEP> 0 <SEP> 5 <SEP> 460 <SEP> 11.9 <SEP> 26.8 <SEP> 18.9 <SEP> 0.6 <SEP> 33.7 <SEP> 0.94 <SEP> 9.6 <SEP> 9.3
<tb> 5 <SEP>"<SEP> 0 <SEP> 10 <SEP> 450 <SEP> 5.6 <SEP> 14.3 <SEP> 11.9 <SEP> 0 <SEP> 40.9 <SEP > 0 <SEP> 19.9 <SEP> 13
<tb> 6 <SEP>"<SEP> 1 <SEP> 5 <SEP> 450 <SEP> 6.4 <SEP> 13.6 <SEP> 9 <SEP> 0 <SEP> 34.8 <SEP> 0 <SEP> 20.4 <SEP> 22.3
<tb> 7 <SEP>"<SEP> 0.4 <SEP> 5 <SEP> 460 <SEP> 11 <SEP> 21.2 <SEP> 12.8 <SEP> 0.5 <SEP> 28.4 <SEP> 0.5 <SEP> 12.5 <SEP> 24
<tb> 8 <SEP>"<SEP> 0.3 <SEP> 5 <SEP> 460 <SEP> 9 <SEP> 17.9 <SEP> 10.8 <SEP> 0.4 <SEP> 37.1 <SEP> 0.8 <SEP> 13.1 <SEP> 19.8
<tb> 9 <SEP> A1 <SEP> + <SEP> 1% B <SEP> + <SEP> 2% C <SEP> 0 <SEP> 5 <SE> 450 <SE> 9.9 <SEP> 24 , 8 <SEP> 15.5 <SEP> 0.4 <SEP> 37.4 <SEP> 1 <SEP> 11 <SEP> 9.7
<tb> 10 <SEP>"<SEP> 0 <SEP> 5 <SEP> 460 <SEP> 12.4 <SEP> 26.3 <SEP> 17.9 <SEP> 0.55 <SEP> 24.5 <SEP> 0.8 <SEP> 12 <SEP> 17.8
<tb> 11 <SEP>"<SEP> 0.5 <SEP> 5 <SEP> 460 <SEP> 12.3 <SEP> 23.5 <SEP> 17 <SEP> 0.4 <SEP> 22.4 <SEP> 0.6 <SEP> 12.7 <SEP> 23.3
<tb> 12 <SEP>"<SEP> 0.8 <SEP> 5 <SEP> 460 <SEP> 8.4 <SEP> 17.8 <SEP> 10.8 <SEP> 0.4 <SEP> 27 , 4 <SEP> 0.5 <SEP> 17.7 <SEP> 25.3
<tb> 13 <SEP> A1 <SEP> + <SEP> 2% B <SEP> 0 <SEP> 5 <SEP> 450 <SEP> 5.4 <SEP> 12.4 <SEP> 13.6 <SEP > 0 <SEP> 27 <SEP> 0 <SEP> 21.8 <SEP> 25.2
<tb> 14 <SEP>"<SEP> 0 <SEP> 5 <SEP> 470 <SEP> 7.6 <SEP> 24.1 <SEP> 25.1 <SEP> 0.6 <SEP> 19.7 <SEP> 0 <SEP> 16.9 <SEP> 13.6
<tb> 15 <SEP>"<SEP> 1 <SEP> 5 <SEP> 450 <SEP> 3.3 <SEP> 5.8 <SEP> 8 <SEP> 0 <SEP> 43.7 <SEP> 0 , 8 <SEP> 15.7 <SEP> 25.9
<tb> 16 <SEP>"<SEP> 1 <SEP> 5 <SEP> 470 <SEP> 5.6 <SEP> 16.3 <SEP> 18.2 <SEP> 0 <SEP> 33.5 <SEP > 0 <SEP> 16.9 <SEP> 15.1
<tb> 17 <SEP> A1 <SEP> + <SEP> 2% B <SEP> + <SEP> 2% C <SEP> 0 <SEP> 5 <SEP> 450 <SEP> 8.9 <SEP> 20 , 4 <SEP> 13 <SEP> 0.48 <SEP> 34.7 <SEP> 0.71 <SEP> 11.2 <SEP> 19.4
<tb> 18 <SEP>"<SEP> 0 <SEP> 5 <SEP> 460 <SEP> 9.5 <SEP> 19.7 <SEP> 14.3 <SEP> 0.57 <SEP> 23.6 <SEP> 0.42 <SEP> 16 <SEP> 25.3
<tb> 19 <SEP>"<SEP> 0.4 <SEP> 5 <SEP> 450 <SEP> 7.5 <SEP> 15.3 <SEP> 10.2 <SEP> 0.33 <SEP> 35 , 5 <SEP> 0.68 <SEP> 14.2 <SEP> 23.8
<tb> 20 <SEP>"<SEP> 0.4 <SEP> 5 <SEP> 460 <SEP> 8.35 <SEP> 17.1 <SEP> 11.4 <SEP> 0.48 <SEP> 30 , 3 <SEP> 0.57 <SEP> 15 <SEP> 25
<tb> * The molar conversion represents the total propane converted into different products ** The selectivity indicates, for each product, the percentage of this obtained compared to converted propane
Examples 21 to 25
Gentle oxidation of isobutane on catalysts of
type A + b% B + c% C.

 The procedure is as for Examples 3 to 20, replacing the butane with isobutane.

The results are reported in Table II. Table II: Managed Oxidation of Isobutane on catalysts of type A + b% B + c% C

Ex. <SEP> Catalysts <SEP> H2O / <SEP> D <SEP> T <SEP> Conversion <SEP> Selectivity <SEP> (%)
<tb> isobutane <SEP> (l / h) <SEP> (C) <SEP> (%)
<tb> (SEP report> CO <SEP> CO2 <SEP> Ethy- <SEP> Propene <SEP> Methacrylate <SEP> Acid
<tb> molar) <SEP> lene <SEP> methacrylic lee <SEP>
<tb> 21 <SEP> A3 * <SEP> 0 <SEP> 5 <SEP> 450 <SEP> 9.2 <SEP> 30.4 <SEP> 29.6 <SEP> 0.14 <SEP> 0, 96 <SEP> 38.9 <SEP> n / a
<tb> 22 <SEP> A4 ** <SEP> + <SEP> 10% B <SEP> 0 <SEP> 5 <SEP> 440 <SEP> 10 <SEP> 33 <SEP> 55.7 <SEP> 0 , 7 <SEP> 0.6 <SEP> 10 <SEP> nd
<tb> 23 <SEP> A4 <SEP> + <SEP> 10% B <SEP> 1.24 <SEP> 5 <SEP> 440 <SEQ> 4.6 <SEP> 21.3 <SEP> 29.4 <SEP> 0.3 <SEP> 0 <SEP> 49 <SEP> n / a
<tb> 24 <SEP> A4 <SEP> + <SEP> 10% B <SEP> 1.24 <SEP> 5 <SEP> 460 <SEP> 7.0 <SEP> 27.6 <SEP> 37.4 <SEP> 0.4 <SEP> 0 <SEP> 34.7 <SEP> n / a
<tb> 25 <SEP> A1 <SEP> + <SEP> 1% B <SEP> + <SEP> 2% C <SEP> 0 <SEP> 10 <SEQ> 460 <SEP> 8.2 <SEP> 27 , 7 <SEP> 29.4 <SEP> 0.4 <SEP> 6.7 <SEP> 23.8 <SEP> 11
<tb> * A3 is y / x = 6; ** A4 corresponds to y = x.

nd: not determined

Claims (10)

 1 - Catalyst for the controlled and selective oxidation of alkanes to the corresponding alkenes and aldehydes and carboxylic acids with ethylenic unsaturation, characterized in that it corresponds to the formula (Nio) X (MoO3) ye (Te2MoO7) z ( P2 5) t in which x, y, z and t represent the mass percentages in the active mass of the respective active ingredients, namely Ni, Mo, Te and P, and satisfy the following relationships  0.1% <x + y <15%  O% <z <10%  0% <t <10%; and  1,2 <y / x <9  2 - Catalyst according to claim I, characterized in that 0.1% <z <10%.  3 - Catalyst according to one of claims 1 and 2, characterized in that it has a specific surface area of between 20 and 50 m 2 / g and an average particle size of between 0.1 and 5 mm.  4 - Catalyst according to one of claims 1 to 3, characterized in that it is in the unsupported state.  5 - Catalyst according to one of claims 1 to 3, characterized in that it is in the form of a mixture with a diluent or solid or inert support.  6 - Process for manufacturing the catalyst as defined in one of claims 1 to 5, characterized in that it comprises  the preparation of a first powdery precursor  consisting of a nickel molybdate of general formula  (NiO) x (MoO3) y, from an aqueous solution of  nickel nitrate and an aqueous acid solution  molybdic; with, as the case may be  the preparation of a second powdery precursor  consisting of a tellurium molybdate of formula  Te2MoO7, from an aqueous solution of  ammonium paramolybdate and an aqueous solution  of telluric acid  impregnation of said first precursor with a solution  aqueous (NH4) 2HPO4 to obtain a precursor  impregnated pulp of general formula (NiO), (Moo) y (P 2 O 5) t; and  the homogeneous mixture of said impregnated precursor  powder and said second powder precursor for  get the desired catalyst  (NiO) x. (MoO3) y. (Te2MoO7) z. (P2o5) t, the mass percentages x, y, z and t being adjusted to the desired final values by the choice of the relative quantities of the starting constituents and the parameters of the process.  7 - Process according to claim 6, characterized in that it comprises a heat treatment of the first powder precursor and / or the second powder precursor and / or the first impregnated powder precursor and / or final catalyst, each heat treatment being conducted at a temperature between 200 ° C and 700 ° C for a period of between 15 minutes and 24 hours.  8 - Process according to one of claims 6 and 7, characterized in that it comprises a final step of thermal activation of the catalyst consisting in bringing it in step with the operating temperature of the oxidation and selectively the alkane, in the oxidation reactor, and maintain it at this temperature for a period of time between 5 minutes and 10 hours before introducing the reaction mixture into said oxidation reactor.  9 - Process for the controlled and selective oxidation of a linear, branched or cyclic alkane containing from 2 to 20 carbon atoms, in particular propane and isobutane, leading to the alkene as well as to the aldehyde corresponding and the corresponding carboxylic acid, comprising contacting said alkane with molecular oxygen or a molecular oxygen-containing gas at a temperature between 400 ° C and 700 ° C, at a pressure of between 0.5 and 10 bar, and in the presence of a catalyst, characterized in that a catalyst as defined in one of claims 1 to 5 is used.  10 - Process according to claim 9, characterized in that the oxidation is conducted with an apparent contact time of between 0.01 and 30 seconds, and with a molar ratio of alkane to oxygen between 0 , 1 and 30.