EP1453785A2

EP1453785A2 - Method for producing acrylic acid from propane in the absence of molecular oxygen

Info

Publication number: EP1453785A2
Application number: EP02799759A
Authority: EP
Inventors: Jean-Luc Dubois; Stéphanie SERREAU; Julien Jacquel
Original assignee: Atofina SA
Current assignee: Arkema France SA
Priority date: 2001-11-30
Filing date: 2002-11-28
Publication date: 2004-09-08
Also published as: FR2833005B1; AU2002364406A8; FR2833005A1; US7161028B2; US20050054880A1; AU2002364406A1; WO2003045886A2; CN1286794C; WO2003045886A3; CN1596244A; KR20040058339A; JP2005510553A

Abstract

The invention concerns a method for producing acrylic acid from propane in the absence of molecular oxygen. Said method is characterized in that it consists in passing a gas mixture free of molecular oxygen and comprising propane, water vapour, as well as, optionally, an inert gas, over a catalyst including molybdenum, vanadium, tellurium, oxygen and at least another element X selected among niobium, tantalum, tungsten, titanium, aluminium, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium, and on a co-catalyst of formula (II): Mo1Bia'Feb'Coc'Nid'Ke'Sbf'Tig'Sih'Cai'Nbj'Tek'Pbl'Wm'Cun'. The invention also concerns a solid catalytic composition comprising said catalyst and co-catalyst and the use of said composition for producing acrylic acid from propane.

Description

PROCESS FOR THE MANUFACTURE OF ACRYLIC ACID FROM PROPANE

AND IN THE ABSENCE OF MOLECULAR OXYGEN

The present invention relates to the production of acrylic acid from propane in the absence of molecular oxygen.

It is known, from European patent application No. 608 838, to prepare an unsaturated carboxylic acid, such as acrylic acid, from an alkane such as propane, by subjecting this alkane to a reaction of catalytic oxidation in the vapor phase possibly devoid of molecular oxygen and in the presence of a catalyst containing a mixed metal oxide essentially comprising molybdenum, vanadium, tellurium, oxygen and at least one other element X chosen from niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron 1 'indium and cerium, the proportions of these elements satisfying the following conditions: 0.25 <r _Mo <0.98 0.003 <r _v <0.5 0, 003 <r _Te <0, 5 0, 003 <r _x <0.5 in which r _Mo , r _v , r _Te and r _x represent respectively the molar fractions of Mo, V, Te and X, based on the sum of the numbers of moles of all the elements of the catalyst, except oxygen.

• This process has the major drawback of producing propionic acid as a by-product. This acid poses problems in certain applications of acrylic acid when it is present in too large a quantity. The invention therefore aims to reduce the production of propionic acid in such a process. Thus, the subject of the invention is a process such as that which has just been described but in which the gaseous mixture is also passed over a co-catalyst.

A more specific subject of the invention is therefore a process for manufacturing acrylic acid from propane, in which a gaseous mixture devoid of molecular oxygen and comprising propane, steam, as well as , where appropriate, an inert gas, on a catalyst comprising molybdenum, vanadium, tellurium, oxygen and at least one other element X chosen from niobium, tantalum, tungsten, titanium, aluminum , zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium, to oxidize propane according to the following redox reaction (1):

Oxidized SOLID + PROPANE - _reduced SOLID + ACRYLIC ACID (1)

this process being characterized in that the gaseous mixture is also passed over a co-catalyst of formula (II)

MθιBia <Fe _b 'Co _c <Ni _d' K _e <Sb _f - Ti _g - Si _h <Cai <Nb. Te _k . P ι <W _{ra '} Cu _n <(II)

in which :

- a 'is between 0.006 and 1, limits included

- b 'is between 0 and 3.5, bounds included c' is between 0 and 3.5, bounds included is between 0 and 3.5, bounds included e 'is between 0 and 1, bounds included; f is between 0 and 1, limits included;

- g 'is between 0 and 1, limits included;

- h 'is between 0 and 3.5, limits included

- i 'is between 0 and 1, limits included j' is between 0 and 1, limits included

- k 'is between 0 and 1, limits included l is between 0 and 1, limits included

- m 'is between 0 and 1, limits included; and - is between 0 and 1, limits included.

Such a process therefore makes it possible to greatly reduce the propionic acid / acrylic acid ratio at the outlet of the reactor. In addition, it also decreases the formation of acetone, which is also a by-product of the manufacture of acrylic acid from propane.

Another subject of the invention is a solid catalytic composition comprising: a) the catalyst as defined above; as well as b) the co-catalyst as defined above.

Other characteristics and advantages of the invention will now be described in detail in the description which follows.

DETAILED DESCRIPTION OF THE INVENTION The co-catalyst used in the process according to the invention corresponds to formula (II) indicated above. The oxides of the different metals used in the composition of the mixed oxide of formula (II) can be used as raw materials in the preparation of this composition, but the raw materials are not limited to oxides; as other raw materials, there may be mentioned: - in the case of molybdenum, ammonium molybdate, ammonium paramolybdate, ammonium heptamolybdate, molybdic acid, molybdenum halides or oxyhalides such as MoCl ₅ , organometallic molybdenum compounds such as molybdenum alkoxides such as Mo (OC ₂ H ₅ ) ₅ , acetylacetone molybdenyl; - in the case of vanadium, ammonium metavanadate, vanadium halides or oxyhalides such as VC1 ₄ , VC1 ₅ or V0C1 ₃ , organometallic compounds of vanadium such as vanadium alkoxides such as

VO (OC ₂ H ₅ ) ₃ ; - in the case of niobium, niobic acid, Nb2 (C204) 5, niobium tartrate, niobium hydrogen oxalate, oxotrioxalatoammonium niobiate {(NH4) 3 [Nb0 (C204) 3] "l , 5H2θ}, niobium and ammonium oxalate, niobium and tartrate oxalate, halides or oxyhalides of nobium such as NbCl3, EbC15 and organometallic compounds of niobium such as niobium alkoxides such as Nb (0C2H5 ) 5, Nb (0-n-Bu) 5;

- in the case of nickel, cobalt, bismuth, iron or potassium, the corresponding nitrates; and, in general, all the compounds capable of forming an oxide by calcination, namely, the metallic salts of organic acids, the metallic salts of mineral acids, the complex metallic compounds, etc. The silicon source generally consists of colloidal silica.

According to particular embodiments, solid compositions of formula (II) can be prepared by mixing, with stirring, aqueous solutions of niobic acid, ammonium heptamolybdate, ammonium metavanadate, telluric acid, preferably adding colloidal silica, then precalcining in air at about 300 ° C and calcining under nitrogen at about 600 ° C.

Preferably, in the co-catalyst of formula (II):

- a 'is between 0.01 and 0.4, limits included;

- b 'is between 0.2 and 1.6, limits included

- it is between 0.3 and 1.6, limits included d is between 0.1 and 0.6, limits included - e 'is between 0.006 and 0.01, limits included

- f is between 0 and 0.4, limits included;

- g 'is between 0 and 0.4, limits included;

- h 'is between 0.01 and 1.6, limits included;

- i 'is between 0 and 0.4, limits included - j' is between 0 and 0.4, limits included

- k 'is between 0 and 0.4, limits included

- l is between 0 and 0.4, limits included - m 'is between 0 and 0.4, limits included; and

- is between 0 and 0.4, limits included.

According to one embodiment of the invention, the catalyst is such as that used in the process of the above-mentioned European patent application No. 608 838, and in particular, the catalyst of formula MθιV ₀ , ₃ Te ₀ , ₂₃ Nbo, ιO _n , the preparation of which is described in Example 1 of this patent application.

According to a preferred embodiment of the invention, the catalyst corresponds to the following formula (I):

MθιN _a Te _b Nb _c Si _d O _x (I)

in which: a is between 0.006 and 1, limits included b is between 0.006 and 1, limits included c is between 0.006 and 1, limits included d is between 0 and 3.5, limits included; and - x is the quantity of oxygen linked to the other elements and depends on their oxidation states, Advantageously: a is between 0.09 and 0.8, limits included

- b is between 0.04 and 0.6, limits included - c is between 0.01 and 0.4, limits included; and d is between 0.4 and 1.6, limits included. Such a catalyst can be prepared in the same way as the co-catalyst of formula (II) and from the same raw materials with, in addition, as tellurium source, tellurium oxide, telluric acid or, of a in general, all the compounds capable of forming a tellurium oxide by calcination, namely, metallic salts of organic acids, metallic salts of mineral acids, complex metallic compounds, etc.

According to the invention, the manufacture of acrylic acid is carried out by passing a gaseous mixture lacking of molecular oxygen and comprising propane and water vapor, as well as, if appropriate, an inert gas, on a catalyst and a cocatalyst as defined above, to conduct the reaction redox (1) as indicated above.

The mass ratio of the catalyst to the co-catalyst is generally greater than 0.5 and preferably at least 1.

According to an advantageous embodiment of the invention, the catalyst and the cocatalyst are located in the same reactor. Thus, the redox reaction is carried out in a single step.

The catalyst and the cocatalyst can be in the form of a solid catalytic composition.

They may each be in the form of grains, the grains of catalyst and of cocatalyst being mixed before the implementation of the process according to the invention.

The catalyst and the cocatalyst can also be in the form of a solid catalytic composition composed of grains, each of which comprises both the catalyst and the cocatalyst.

Generally, the redox reaction (1) is carried out at a temperature of 200 to 500 ° C, preferably from 250 to 450 ° C, more preferably still, from 350 to 400 ° C. The pressure is generally from 1.01.10 ⁴ to 1.01.10 ^e Pa

(0.1 to 10 atmospheres), preferably 5.05.10 ⁴ to 5.05.10 ⁵ Pa

(0.5-5 atmospheres).

The residence time is generally 0.01 to 90 seconds, preferably 0.1 to 30 seconds. The propane / water vapor volume ratio in the gas phase is not critical and can vary within wide limits.

Likewise, the proportion of inert gas, which may be helium, krypton, a mixture of these two gases, or nitrogen, carbon dioxide, etc., is also not critical and may also vary within wide limits. As an order of magnitude of the proportions of the starting mixture, the following ratio (by volume) can be cited: propane / inert (He-Kr) / H ₂ 0 (vapor): 10-20 / 40-50 / 40-50

During the redox reaction (1), the solid composition undergoes a reduction and, in general, a progressive loss of its activity. This is why, once the solid composition has at least partially gone to the reduced state, the regeneration of said solid composition is carried out according to reaction (2):

SOLID _reduced + 0 ₂ - SOLIDoxidized (2) by heating in the presence of oxygen or an oxygen-containing gas at a temperature of 250 to 500 ° C., for the time necessary for the reoxidation of the solid composition.

The process is generally carried out until the reduction rate of the solid composition is between

10 and 40%. This reduction rate can be monitored during the reaction by the quantity of products obtained. The equivalent amount of oxygen is then calculated. It can also be followed by the exothermicity of the reaction.

After the regeneration, which can be carried out under conditions of temperature and pressure identical or different from those of the redox reaction, the solid composition regains initial activity and can be used in a new reaction cycle.

The redox reaction (1) and the regeneration can be carried out in a conventional reactor, such as a fixed bed reactor, a fluidized bed reactor or a transported bed reactor.

The redox reaction (1) and the regeneration can therefore be carried out in a two-stage device, namely a reactor and a regenerator which operate simultaneously and in which two charges of solid composition alternate periodically; we can also conduct the reaction redox (1) and regeneration in the same reactor by alternating the reaction and regeneration periods.

Preferably, the redox reaction (1) and the regeneration are carried out in a reactor with a transported catalyst bed.

You can use a single pass or recycle mode of operation.

According to a preferred embodiment, the propylene produced as a secondary product and / or the unreacted propane are recycled (or returned) to the inlet of the reactor, that is to say that they are reintroduced to the 'inlet of the reactor, in mixture or in parallel with the starting mixture of propane, water vapor and if necessary inert gas (ies).

Examples

The following examples illustrate the present invention without, however, limiting its scope.

In the formulas given in Examples 1 to 3, x is the quantity of oxygen linked to the other elements and depends on their oxidation states.

The selectivities and yields are defined as follows:

Number of moles of acrylic acid formed

Selectivity (%) = x 100 in acrylic acid Number of moles of propane reacted

Number of moles of acrylic acid formed

Yield (%) = x 100 in acrylic acid Number of moles of propane introduced

The selectivities and yields relative to the other compounds are calculated in a similar manner.

Example 1

Preparation of catalyst A of formula Mo_Vo _{t 3} _Jiibo, ιιTeo, z2Sio.9sO _x a) Preparation of a niobium solution In a 5 1 beaker, 640 g of distilled water are introduced and then 51.2 g of niobic acid (ie 0, 304 moles of niobium). We then add 103.2 g (0.816 mole) of oxalic acid dihydrate.

The oxalic acid / niobium molar ratio is therefore 2.69.

The solution obtained above is heated at 60 ° C for 2 hours, covering to avoid evaporation and stirring. A white suspension is thus obtained which is allowed to cool with stirring to 30 ° C, which lasts for about 2 hours.

b) Preparation of a solution of Mo, V and Te

2120 g of distilled water, 488 g of ammonium heptamolybdate (or 2.768 moles of molybdenum), 106.4 g of ammonium metavanadate NHVO ₃ (or 0.912 mole of vanadium) are introduced into a 5 l beaker. and 139.2 g of telluric acid

(supplier: FLUKA) (i.e. 0.608 mole of tellurium).

The solution obtained above is heated to 60 ° C. for

1 hour and 20 minutes, covering to avoid evaporation and stirring. This gives a clear red solution which is allowed to cool with stirring to 30 ° C, which lasts for about 2 hours.

c) Introduction of silica

393.6 g of Ludox silica (containing 40% by weight of silica, supplied by the company Dupont) are introduced with stirring into the solution of Mo, V and Te prepared above. The latter retains its clarity and red coloration.

The niobium solution prepared above is then added. A fluorescent orange gel is thus obtained after a few minutes of stirring. This solution is then spray dried. The atomizer used is a laboratory atomizer (ATSELAB from the company Sodeva). The atomization takes place under a nitrogen atmosphere (in order to avoid any oxidation and any untimely combustion of the oxalic acid present in the slip).

The operating parameters are overall: - nitrogen flow rate of the order of 45 Nm3 / h; slip flow of the order of 500 g / h; gas inlet temperature between 155 ° C and 170 ° C; gas outlet temperature between 92 ° C and 100 ° C. The recovered product (355.2 g), which has a particle size of less than 40 microns, is then placed in an oven at 130 ° C. overnight in a teflon-coated tray. 331 g of dry product are thus obtained.

d) Calcination

The precalcinations and calcinations were carried out under air and nitrogen flow in steel capacities. These capacities are directly installed in muffle furnaces and the air supply is through the chimney. An internal thermowell allows proper temperature control. The cover is useful to avoid a return of air to the catalyst.

First of all, the 331 g of the precursor obtained previously is precalcined for 4 hours at 300 ° C. under an air flow of 47.9 ml / min / g of precursor.

The solid obtained is then calcined for 2 hours at 600 ° C. under a nitrogen flow of 12.8 ml / min / g of solid.

Catalyst A is thus obtained.

Example 2

Preparation of co-catalyst B of formula

MθχBi _0ι 22K0, ooβSbo, osSi o, 6β _x

A solution A is prepared by dissolving 79.7 g of ammonium heptamoblydate in 220.3 g of water at room temperature, with stirring, for 5 minutes.

A colorless solution A is thus obtained.

A solution B is prepared by dissolving 51.5 g of cobalt nitrate and 0.3327 g of potassium nitrate in 55 g of water at room temperature, with stirring, for 5 minutes. This gives a purple solution B. A solution C is prepared by dissolving 56.4 g of iron nitrate, 19.3 g of bismuth nitrate and 28.6 g of nickel nitrate in 85.1 g of water as follows: the nitrates are introduced in a small amount of water, 4.4 g of 68% nitric acid are added, then the rest of the water is added. The mixture is stirred for 30 to 45 minutes.

This gives a green solution C.

A solution D is prepared by dissolving 44.5 g of LUDOX AS40 silica in 16.4 g of distilled water at room temperature, with stirring.

This gives a solution D.

Then pour solution B into solution A and stir for 10 minutes. Then, 5.9 g of antimony trioxide and solution C are added over 10 minutes. Finally, solution D is added over 10 minutes followed by 16.2 g of ammonia (28% by weight) to bring the pH of the solution to 2.3.

While continuing stirring, the temperature is increased to 70 ° C and maintained at this temperature for 90 minutes.

Evaporation is then carried out under vacuum with a water bath and with stirring, until a thick gel is obtained. The drying of the precursor is then completed in an oven at 130 ° C for 24 hours. 158.3 g of dry precursor are thus recovered. The calcination is carried out in air (47 ml / min / g of precursor) according to the following programming:

- temperature rise from 2 ° C / min to 320 ° C;

- level off at 320 ° C for 2 hours;

- temperature rise from 2 ° C / min to 540 ° C; - level at 540 ° C for 999 minutes (16.7 hours).

23.9 g of co-catalyst B are thus obtained.

Example 3

Preparation of co-catalyst C of formula MOxBi

a) Preparation of the precursor A solution of 7970.0 g of ammonium heptamolybdate in 22000 g of distilled water is added, in a mixer, to a solution of 5151 g of cobalt nitrate hexahydrate and. 33.0 g of potassium nitrate in 5000 g of water. The resulting solution is stirred for 10 minutes at room temperature. 127.6 g of Ti0 ₂ with a particle size of less than 1 micron are then poured into it. Then, in 10 minutes, a solution consisting of:

5637 g of non-hydrated ferric nitrate, - 1920 g of bismuth nitrate pentahydrate, 2859 g of nickel nitrate hexahydrate,

- 417 g of 68% nitric acid and

- 8500 g of distilled water.

Finally, 594 g of a colloidal silica solution containing 30% by weight of silica in 1500 g of distilled water are introduced over 5 minutes.

The mixture is kept stirring at room temperature. Then the temperature is gradually increased to 70 ° C. The mixture is kept stirred at this temperature for 90 minutes. Then, the heating and stirring are stopped and the mixture is allowed to cool to room temperature. The mixture contains approximately 33% by weight of solid matter and its pH is less than 1. The mixture is then micronized in a ball mill until particles are obtained whose average size is less than 2 microns.

b) Preparation of a polysilicic acid solution (APS) at 6% by weight of silica This solution is prepared by diluting 1091 g of a sodium silicate solution (360 g of silica) with 4909 g of distilled water . This solution is mixed for a few minutes; the pH of this mixture is approximately 12. Then, with vigorous stirring, a sulfonic cation exchange resin sold by the company Dow Chemicals under the trademark DOWEX Monosphere 650C (H) is added, until the pH of the mixture is between 2.5 and 3. Then the resin is filtered and the filtrate is stored in ice and must be used within the next hour to prepare a precursor suspension-PSA solution for atomization.

c) Preparation and atomization of the precursor suspension - APS solution

1110 g of the APS solution with 6% silica (obtained in the previous step) are added to 2000 g of the mixture of micronized precursor and the whole is kept under stirring in ice. The resulting suspension, which contains 22.7% solids, has a pH of 1 ± 0.1. This suspension is atomized at a speed of about 200 ml / min, with a nozzle pressure of 0.3 bar and a temperature chamber temperature of 390 ° C, so as to obtain porous microspheres, usable in the redox process, in a transported bed.

d) Calcination

The microspheres collected under the atomizer chamber are calcined in an oven by heating from room temperature to 90 ° C in 1 hour, maintaining the temperature at 90 ° C for 2 hours, then heating to 300 ° C in 2 hours, maintaining the temperature at 300 ° C for 5 hours, then heating to 550 ° C in 2 hours and maintaining the temperature at 550 ° C for 6 hours. The desired cocatalyst C is thus obtained.

Example 4 a) Procedure

The operating mode implemented is detailed below. A first height of 1 ml of silicon carbide in the form of particles of 0.62 mm in diameter is loaded into a vertical reactor from the bottom up, a second height of 1 ml of silicon carbide in the form of particles of 0.125 mm in diameter and 5 g of catalyst in the form of particles of 0.02 to 1 mm, then a third height of silicon carbide in the form of particles of 1.19 mm in diameter. The reactor is then heated to 250 ° C and the vaporizer to 200 ° C. The electric priming of the water pump is activated.

Once the reactor and the vaporizer have reached the temperatures indicated above, the water pump is activated and the temperature of the reactor is raised to 380 ° C. and it is waited 30 minutes for the hot point to be stabilized.

Then, oxygen is introduced in 10 pulses of 23 seconds each to oxidize the catalyst well. The catalyst is considered to be completely oxidized when the temperature of the hot spot has stabilized, that is to say when there is no longer any exotherm due to the reaction (by following the temperature of the catalyst measured by means of 'a thermocouple placed in the catalytic bed, we can see the temperature fluctuations as a function of the pulses). With regard to the production of acrylic acid proper, a redox balance is made up of 60 redox cycles. A redox cycle represents:

- 9.5 or 12 seconds of propane, as the case may be, in a continuous flow of helium-krypton / water, - 45 seconds of continuous flow of helium-krypton / water,

- 20 seconds of oxygen in a continuous flow of helium-krypton / water,

- 45 seconds of continuous helium-krypton / water flow. During the assessment, four liquid samples are taken, each representing 15 cycles. 4 gas samples are also taken using gas bags, each sample representing approximately 15 cycles.

Each small washing bottle (25 ml of capacity and filled with 20 ml of water) is equipped with a gas pocket, and when the bottle is connected to the outlet of the reactor (as soon as the liquid bubbles) ), the pocket is opened and the stopwatch is started.

To check the oxidation state of the catalyst, a new series of 10 pulses of 23 seconds of oxygen is carried out. It shows that the solid state of oxidation was maintained during the balance. Liquid effluents are analyzed on an HP 6890 chromatograph, after performing a specific calibration.

The gases are analyzed during the balance on a micro-GC Chrompack chromatograph. An acidity assay is carried out on each bottle to determine the exact number of moles of acid produced during each micro-balance and to validate the chromatographic analyzes.

The final result which is rendered corresponds to the average of the micro-assessments carried out on the 4 washing bottles and the 4 gas pockets.

b) Results bl) Tl and T2 tests A first Tl test was carried out with 5 g of catalyst A. The duration of the propane pulses had been adjusted to approximately 9.5 s, by adjusting the opening time of the mass flow meter. The number of moles of propane sent to the catalyst is thus predetermined. We proceed as described above. The results obtained are collated in Table 1.

A second T2 test was carried out, by loading into the reactor, instead of the 5 g of catalyst A, a mechanical mixture of 5 g of catalyst A and 5 g of co-catalyst B. The operating parameters were identical. The results obtained are recorded in Table 1 below.

It is therefore found that the addition of the cocatalyst makes it possible to reduce the propionic acid / acrylic acid ratio from 0.75% to 0.20%. In addition, the acetone / acrylic acid ratio drops from 1.64% to 0.59%.

b2) T3 and T4 tests A third T3 test was carried out with 5 g of catalyst A. The duration of the propane pulses had been adjusted to approximately 12 s, by adjusting the opening time of the mass flow meter. The number of moles of propane sent to the catalyst is thus predetermined. We proceed as described above. The results obtained are collated in Table 2.

A fourth test T4 was carried out, by loading into the reactor, instead of the 5 g of catalyst A, a mechanical mixture of 5 g of catalyst A and 5 g of co-catalyst C. The operating parameters were identical. The results obtained are recorded in Table 2 below.

It can therefore be seen that the addition of the cocatalyst makes it possible to reduce the propionic acid / acrylic acid ratio from 0.35% to 0.09%. In addition, the acetone / acrylic acid ratio drops from 0.09% to 0.38%.

Claims

Process for the production of acrylic acid from propane, in which a gaseous mixture devoid of molecular oxygen and comprising propane, water vapor and, where appropriate, an inert gas, is passed over a catalyst comprising molybdenum, vanadium, tellurium, oxygen and at least one other element X chosen from niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium, to oxidize propane according to the following redox reaction (1) :

SOLIDEoxyrdé + PROPANE -> REDUCED _SOLID + ACRYLIC ACID (1)

OiBi _a - Fe _b - Co _c <Ni _d > KO Sb _f -Ti _g . If _h <Ca ^ Nb-,. Te _k <Pbi-W _m - Cu _n - (II]

in which: a 'is between 0.006 and 1, limits included; b 'is between 0 and 3.5, limits included c' is between 0 and 3.5, limits included d 'is between 0 and 3.5, limits included - e' is between 0 and 1, limits included f is between 0 and 1, bounds included g 'is between 0 and 1, bounds included h' is between 0 and 3.5, bounds included i 'is between 0 and 1, bounds included j' is included between 0 and 1, limits included k 'is between 0 and 1, limits included is between 0 and 1, limits included m 'is between 0 and 1, limits included; and n 'is between 0 and 1, limits included.

2. Method according to claim 1, in which, in the cocatalyst of formula (II): a 'is between 0.01 and 0.4, limits included; b 'is between 0.2 and 1.6, limits included c' is between 0.3 and 1.6, limits included d 'is between 0.1 and 0.6, limits included - e' is included between 0.006 and 0.01, limits included f is between 0 and 0.4, limits included; g 'is between 0 and 0.4, limits included; h 'is between 0.01 and 1.6, limits included; i 'is between 0 and 0.4, limits included - j' is between 0 and 0.4, limits included k 'is between 0 and 0.4, limits included l' is between 0 and 0.4 , limits included is between 0 and 0.4, limits included; and n 'is between 0 and 0.4, limits included.

3. Method according to claim 1 or claim 2, in which the proportions of the elements of the catalyst satisfy the following conditions:

0.25 <r _Mo <0.98 0.003 <r _v <0.5 0.003 <r _Te <0.5 0.003 <r _x <0.5 in which r _Mo , r _v , r _Te and r _x represent the molar fractions, respectively, of Mo, V, Te and X, relative to the sum of the numbers of moles of all the elements of the catalyst, with the exception of oxygen.

4. Method according to claim 1 or claim 2, in which the catalyst corresponds to the following formula (I):

MOiVaTe _b NbcSi _d Ox (I) in which: a is between 0.006 and 1, limits included

- b is between 0.006 and 1, limits included - c is between 0.006 and 1, limits included d is between 0 and 3.5, limits included; and

- x is the quantity of oxygen linked to the other elements and depends on their oxidation states.

5. Method according to claims 4, wherein, in formula (I): a is between 0.09 and 0.8, limits included

- b is between 0.04 and 0.6, limits included c is between 0.01 and 0.4, limits included; and - d is between 0.4 and 1.6, limits included.

6. Method according to one of claims 1 to 5, in which a mass ratio of the catalyst to the cocatalyst is greater than 0.5 and preferably at least 1.

7. Method according to one of claims 1 to 6, in which the catalyst and the cocatalyst are mixed.

8. Method according to one of claims 1 to 7, wherein the catalyst and the cocatalyst are in the form of grains, each grain comprising both the catalyst and the cocatalyst.

9. Method according to one of claims 1 to 8, in which the redox reaction (1) is carried out at a temperature of 200 to

500 ° C and preferably from 250 to 450 ° C.

10. Method according to one of claims 1 to 9, in which the redox reaction (1) is carried out under a pressure of 1.01.10 ⁴ to 1.01.10 ⁶ Pa (0.1 to 10 atmospheres) and preferably 5 , 05.10 ⁴ to 5.05.10 ⁵ Pa (0.5-5 atmospheres).

11. Method according to one of claims 1 to 10, in which the redox reaction (1) is carried out with a residence time of 0.01 to 90 seconds and preferably from 0.1 to 30 seconds.

12. Method according to one of claims 1 to 11, characterized in that once the solid composition has at least partially gone to the reduced state, the regeneration of said solid composition is carried out according to the reaction (2):

S0LIDE _reduced + 0 ₂ "SOLID oxidized (2)

by heating in the presence of oxygen or of an oxygen-containing gas at a temperature of 250 to 500 ° C., for the time necessary for the reoxidation of the solid composition.

13. Method according to the preceding claim, characterized in that the redox reaction (1) and the regeneration are carried out in a two-stage device, namely a reactor and a regenerator which operate simultaneously and in which periodically alternate two charges of solid composition.

14. Method according to claim 12, characterized in that the redox reaction (1) and the regeneration are carried out in the same reactor, alternating the reaction and regeneration periods.

15. The method of claim 12, characterized in that the redox reaction (1) and the regeneration are carried out in a transported bed reactor.

16. Method according to one of claims 1 to 15, characterized in that the propylene produced and / or the unreacted propane are recycled at the inlet of the reactor.

17. Solid catalytic composition comprising: a) a catalyst comprising molybdenum, vanadium, tellurium, oxygen and at least one other element X chosen from niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium; and b) a co-catalyst of formula (II)

MouBia'Feb'COc'Nid'Ke'Sbf'Tig'Si '(II)

in which: a 'is between 0.006 and 1, limits included - b' is between 0 and 3.5, limits included

C is between 0 and 3.5, limits included d is between 0 and 3.5, limits included e 'is between 0 and 1, limits included f is between 0 and 1, limits included - g' is between 0 and 1, limits included h 'is between 0 and 3.5, limits included i' is between 0 and 1, limits included j 'is between 0 and 1, limits included k' is between 0 and 1, limits included - l is between 0 and 1, limits included m 'is between 0 and 1, limits included; and n 'is between 0 and 1, limits included.

18. Solid catalytic composition according to claim 17, in which: i) the catalyst corresponds to the following formula (I):

MθιV _a Te _b Nb _c Si _d O _x (I)

in which: a is between 0.006 and 1 and preferably between 0.09 and 0.8, limits included; b is between 0.006 and preferably between 0.04 and 0.6, limits included; c is between 0.006 and preferably between 0.01 and 0.4, limits included; d is between 0 and 3.5 and preferably between 0.4 and 1.6, limits included; and x is the amount of oxygen bound to the other elements and depends on their oxidation states; and

ϋ) in the co-catalyst of formula (II): a 'is between 0.01 and 0.4, limits included b' is between 0.2 and 1.6, limits included

C is between 0.3 and 1.6, limits included d 'is between 0.1 and 0.6, limits included e' is between 0.006 and 0.01, limits included f 'is between 0 and 0 , 4, terminals included; g 'is between 0 and 0.4, limits included; h 'is between 0.01 and 1.6, limits included; i 'is between 0 and 0.4, limits included j' is between 0 and 0.4, limits included k 'is between 0 and 0.4, limits included l' is between 0 and 0.4, bounds included is between 0 and 0.4, bounds included; and n 'is between 0 and 0.4, limits included

19. Solid catalytic composition according to claim 17 or claim 18 being in the form of grains, each grain comprising both the catalyst and the cocatalyst.

20. Use of a solid composition according to one of claims 17 to 19 in the manufacture of acrylic acid from propane.