KR20010005583A - Catalysts with modified molybdenum oxycarbide base prepared from oriented molybdenum oxide and method for producing same - Google Patents

Abstract

The present invention is characterized in that the specific surface area is made from molybdenum oxide MoO ₃ having a structure comprising a single crystalline wafer oriented in a selective direction obtained by sublimation-condensation and having a catalytic activity, in particular a specific velocity. A modified oxymolybdenum-based catalyst having an improved specific rate and a method of obtaining the catalyst.

Description

Modified oxymolybdenum-based catalyst prepared from oriented molybdenum oxide and a method for preparing the same

French Patents 2,666,520 and 2,712,587 disclose catalysts for the isomerization of C ₄ to C ₂₀ or more straight chain hydrocarbons, for the hydrogenation of aromatic compounds with molybdenum oxycatalysts and for the decyclization reactions. Catalysts for the reaction and decyclicification are described as being obtained by direct activation of the precursor oxide (MoO ₃ ) by the reaction mixture itself.

The oxymolybdenum-based catalyst has been described as providing most of the advantages even when the conversion is high, since the selectivity is always high. It is also much cheaper than conventional Pt-based catalysts and reacts less sensitively by toxic substances.

However, there is still a problem in the petrochemical reaction catalyzed by molybdenum oxycarbide that the specific speed of the reaction, expressed in moles of the converted product per gram of catalyst per second, is not sufficient.

By way of example, this specific rate is 150 for conventional Pt-based catalysts on zeolite supports and generally about 50 for molybdenum oxycarbide prepared by standard methods.

FIELD OF THE INVENTION The present invention relates to catalysts for chemical or petrochemical reactions comprising metal oxycarbides with large specific surface areas, methods for their preparation and their use. Such catalysts are suitable for the purification and conversion of oil products, in particular for the isomerization of saturated hydrocarbons, for the hydrogenation and decyclication of cyclic and aromatic hydrocarbons, and for providing improved catalytic properties, in particular improved specific rates. do.

1 shows the selectivity (%) of n-heptane isomer (iC ₇ ) in relation to the degree of conversion of nC ₇ .

Thus, the inventors have improved the possibility of improving the catalytic performance of this type of catalyst, in particular in order to increase the specific velocity of the petrochemical reaction with respect to the unit weight of the catalyst.

A first feature of the present invention lies in modified molybdenum oxycarbide having a large specific surface area, which is made of molybdenum oxide MoO ₃ having a structure mainly composed of a wafer having a preferred orientation.

The orientation plane of MoO _{3 that} is optimal for obtaining efficient oxycarbide is the plane 010 having the desired orientation improvement in direction 001.

Such wafers have a length of at least 1 μm in the direction of the preferred orientation. It is characteristic that it can be at or larger than 10 000 μm. The thickness of the wafer is generally at least 0.1 μm, the width of which is at least 0.5 μm, which can sometimes be 6,000 μm. They are generally single crystalline and are somewhat tightly packed.

The specific surface area BET of this oxycarbide is greater than 5 m 2 / g, generally greater than 20 m 2 / g and even greater than 90 m 2 / g, which is substantially greater than the specific surface area BET of the initially oriented MoO ₃ . .

This makes it difficult to know the microstructure specificity that gives the unexpected surprising results of the present invention. However, it can be regarded as a detrimental by-product of the reduction reaction, and almost all of the MoO ₂ oxides contained in the oxycarbide obtained from polycrystalline MoO ₃ are almost removed.

A second feature of the present invention is a method of obtaining modified molybdenum oxycarbide having a high specific surface area, using any molybdenum compound (for example, ammonium heptamolybdate) or polycrystalline molybdenum oxide which is converted into an oxide as a starting material. Molybdenum oxide was heat treated by sublimation-condensation in a closed space under an oxidizing gas atmosphere at a temperature of 500 ° C. to 800 ° C. for at least 5 hours to obtain an oriented recrystallized oxide, which was then treated under a flow of a hydrocarbon and hydrogen mixture to modify it. It is characterized by obtaining oxymolybdenum.

The sublimation-condensation step is generally carried out at a slow rate in a static atmosphere or under a flow of dry or wet oxidizing gas, wherein the gas is air as possible. In this way, the recrystallization reaction of molybdenum oxide is carried out in situ without substantially moving the material.

To obtain a supported catalyst, initial oxides or precursors are mixed or attached using or on a material that is inert to the oxide, which material serves as a support for the modified oxycarbide catalyst. Such materials generally include refractory materials such as, for example, alumina, but are preferably carbides having a high specific surface area such as pure SiC or doped SiC.

The obtained recrystallized oxide becomes an oxide having an orientation structure almost including a single crystalline wafer of elongated form having a preferred orientation.

The manufacturing method for producing the oxycarbide from the recrystallized oxide is carried out by the method described in the aforementioned patent document.

A third feature of the present invention is the modification which is made from MoO ₃ which has a high specific surface area and is oriented as a catalyst in petrochemical reactions, in particular hydrocarbon isomerization, in particular hydrogenation of aromatics, to obtain high selectivity and high conversion. It is in the use of molybdenum oxycarbon.

Such catalysts according to the present invention provide much improved activity compared to conventional polycrystalline molybdenum oxycarbide. In particular, this specific rate is about 10 times that of MoOC obtained from polycrystalline MoO ₃ , that is, the amount of catalyst required for the same reaction is less than 10 times. In addition, the specific velocity is also high, and if necessary, it is four times higher than that obtained using a conventional Pt-based catalyst on zeolite.

Specific selectivity or conversion properties for MoOC (higher conversion selectivity much higher than that of Pt) are typically not denatured.

The catalyst of the invention can be prepared as such (ie in bulk) or supported on a SiC support having a high specific surface area, for example as described above.

Various methods for producing bulk or supported oxide phase MoO ₃ having an orientation suitable for obtaining a catalyst comprising modified molybdenum oxycarbide with high activity and selectivity to the isomerization reaction are described below.

The first production method preferably consists of heating the bulk polycrystalline MoO ₃ powder under a slow air flow at a temperature of 650 ° C. to 750 ° C. for a period of 5 to 240 hours. Instead of the molybdenum oxide used, a precursor salt (heptamolybdate) or an oxidized metal wafer or metal powder can be used. After this treatment, the molybdenum oxide takes on the appearance of a powder or wafer with the desired orientation. Other oxygen containing gases may be used instead of the air stream. In general, slow flow air streams may be used in the form of dry gases or in the form that may contain steam. In addition, the synthesis can be carried out under static atmosphere of air or a mixture of oxygen and an inert gas.

The second preparation consists of heating the complete mixture of polycrystalline MoO ₃ and SiC granules, not the polycrystalline MoO ₃ powder. The processing method is the same as that of the 1st manufacturing method. The resulting product consists of a MoO ₃ wafer coated with SiC granules with the desired orientation.

A third preparation consists of impregnating a SiC-based support with a molybdenum salt containing solution, for example a heptamolybdate solution. The support is then dried in a drying oven at 120 ° C. for 12 hours and then calcined under air flow. The temperature is raised to a calcination temperature (650 ° C.-750 ° C.) at room temperature with a gradient of 60 ° C. per minute and then held at this temperature for an additional 24 hours. The gas mixture used is the same as the two gases of the first recipe.

General preparation conditions for bulk or supported molybdenum oxide with preferred orientation are as follows.

The oxidizing gas used is generally air, but can be pure oxygen or oxygen slightly diluted with an inert gas. Mass dilution of oxygen is not necessary and it is preferred to use a gas containing at least 10% oxygen. The gas mixture can be used in anhydrous form or as a vapor containing form as described above.

The treatment temperature should be in the range 500 ° C to 800 ° C. Treatment at temperatures below 500 ° C. will require undesirable treatment times to effect this treatment effectively, and treatment at temperatures above 800 ° C. will cause excessive product evaporation.

-Processing time is longer than 5 hours. Generally, it is 24 to 72 hours when it is carried out in the presence of humid air, and it is 48 to 120 hours when it is carried out in the presence of dry air. However, it may be longer because the performance of the catalyst increases with the duration of the treatment time.

When treated in the presence of humid air, the degree of conversion to oriented oxide can be increased, resulting in a higher amount of recrystallized oxide than in the presence of dry air.

Example 1

This example firstly illustrates how the bulk molybdenum oxide (MoO ₃ ) oriented by the present invention is obtained using the first method, and secondly, for the purpose of catalyzing the isomerization of n-heptane. The manufacturing method which obtains a modified molybdenum oxycarbonide is illustrated.

The oriented oxide was prepared by the following method. 1,000 mg of polycrystalline MoO ₃ chunks are placed in a quartz tube placed inside the tubular oven. These were treated with a stream of dry air (10 cm 3 / min). The oven temperature was raised from room temperature to 680 ° C. at a rate of 20 ° C. per minute. This temperature was maintained for 100 hours. The oven temperature was then reduced to room temperature while maintaining the air flow. MoO ₃ oriented or single crystalline at room temperature was taken out of the oven and stored in a glove box for later conversion to modified oxycarbide according to the invention.

Carbonization and use of some of the bulk oriented oxides obtained in the presence of dry air were carried out under the following conditions.

12 mg of oriented molybdenum oxide (wafer type) mass prepared as described above was placed in a tubular reactor of stainless steel between two layers of silica wool. The reactor was drained under atmospheric pressure for 30 minutes at room temperature under hydrogen flow (higher than 99.95% purity). The pressure of the system was then elevated to 6 bar under hydrogen flow, at which time the reaction temperature was 350 ° C. Once the temperature and pressure are reached, n-heptane is introduced into the hydrogen stream to bring the molar ratio of H ₂ and n-heptane in the mixture to 30 to obtain molybdenum oxycarbide.

Catalyst performance obtained during n-heptane modification was recorded over time to assess for any maturation of the modified molybdenum oxycarbide catalyst. Details of the results obtained and the reaction products obtained are shown in Table 1 below.

In Table 1 below, the elapsed time since start of operation is listed at the top. The line is shown as follows.

The total conversion of the system [% of n-heptane molecules converted by isomerization or cracking distillation];

Specific velocity: number of initial hydrocarbon molecules converted per second, per gram of catalyst,

The total selectivity of the C ₇ isomer [% of isomerized molecule relative to the total converted molecule],

-C ₇ isomer yield (product of the selectivity and conversion of the isomerization reaction,%),

% Of corresponding isomerized species to the total isomers obtained (C ₇ isomers,%).

DMPen = Dimethyl-2,2-pentane + Dimethyl-2,3-pentane + Dimethyl-2,4-pentane

2MHex = methyl-2-hexane

3MHex = methyl-3-hexane

3EPent = ethyl-3-pentane

Cyclic Compounds = Methylcyclohexane + Toluene

-Ratio of the obtained cracked distillation species to the total cracked distillation products obtained (degraded distillation products,%).

The specific surface area BET is 80 m 2 / g.

Isomerization of n-heptane in bulk modified molybdenum oxycarbonate prepared from bulk MoO ₃ oriented in the presence of a dry atmosphere Hour 2.0 15.5 19.5 25.0 41.5 % Conversion 2.3 16.2 16.1 16.1 16.0 Specific velocity (10 ^-7 molg ^{-1s -1} ) 71.0 613.5 620.0 608.4 606.0 iC ₇ selectivity (%) 95 96 96 96 95 iC ₇ reaction yield (%) 2.2 15.6 15.5 15.5 15.4 Distribution of reaction products % Of C ₆ isomers DMPen 9.5 9.6 9.5 9.6 9.6 2Mhex 40.4 40.3 40.1 40.2 40.1 3Mhex 46.4 46.5 46.3 46.7 46.4 3EPen 3.2 3.1 3.1 3.1 3.0 Decomposition distillation products (%) Cyclic compound 0.7 0.5 0.9 0.5 0.8 C ₆ + C ₁ 18.0 17.0 14.0 16.0 19.1 C ₅ + C ₂ 17.9 18.9 13.7 13.1 15.3 C ₄ + C ₃ 60.5 60.8 66.6 67.2 63.5 Etc 3.6 3.3 5.7 3.7 2.2

The following conclusions were obtained from Table 1.

1. The number of converted molecules of n-heptane is very low during the first hour of the reaction. After about 2 hours under the flow of n-heptane and hydrogen, the catalyst becomes active resulting in a significant change in its surface area. This activation is converted to reactive modified oxycarbide by reduction and carbonization of molybdenum oxide oriented in reaction with the reaction mixture (n-heptane / hydrogen) as in the case of polycrystalline molybdenum oxide.

2. C ₇ isomer selectivity is very important at the start of the reaction and remains as high as 95%. The isomeric product formed consists of almost single branched molecules (methyl-2-hexane and methyl-3-hexane) and double branched molecules (dimethylpentane), and cyclic molecules are formed in very small amounts (<1%).

1, the selectivity of the nC ₇ isomer remained very high regardless of the degree of conversion of the reaction.

Example 2

This example firstly illustrates a method of obtaining an Mo oxide oriented by the present invention supported on a SiC-based support using a third method, and secondly SiC to catalyze the isomerization reaction of n-heptane. It will be illustrated how to obtain modified molybdenum oxycarbide supported on a phase.

SiC granules having a specific surface area BET of 19 m 2 / g are impregnated with an aqueous solution of ammonium heptamolybdate and calcined at 350 ° C. for 2 hours to decompose the heptamolybdate to MoO ₃ oxide.

SiC granules were impregnated with polycrystalline MoO ₃ , and the resultant was placed in a ceramic tray, which was then inserted into a quartz tube placed in a tubular oven. The unit was treated with a stream of dry air at a rate of 20 cm 3 · min ⁻¹ . The temperature rise and the rest of the assembly are the same as those used in Example 1. The used temperature was 700 degreeC. The system was held for 72 hours at this temperature. The oven temperature was then cooled to room temperature while maintaining a dry air stream. The monocrystalline MoO ₃ supported on this or oriented product or SiC at room temperature was removed from the oven and stored in a glove box for later conversion to modified oxycarbide.

The carbonization reaction obtained using the orientation and supported oxide obtained in the presence of dry air was carried out as described above.

The C ₇ isomer selectivity and specific velocity obtained on the catalyst with respect to time under flow are listed in Table 2 below. In addition, the details of the distribution of the reaction products are also described in Table 2 below.

Isomerization of n-heptane in modified molybdenum oxycarbide supported on SiC prepared from MoO ₃ supported on oriented SiC in the presence of a dry atmosphere Hour 2 6 10 21 25 49 % Conversion 13.5 20.2 22.6 23.6 22.7 23.5 Specific velocity (10 ^-7 molMoO ₃ g ^{-1s -1} ) 81.0 121.2 872.4 904.2 880.2 896.4 iC ₇ selectivity (%) 94 94 95 95 96 94 iC ₇ reaction yield (%) 12.7 19.0 21.5 22.5 21.8 22.1 Distribution of reaction products % Of C ₆ isomers DMPen 9.1 10.2 9.4 9.0 8.8 8.7 2Mhex 34.5 41.6 40.5 41.2 40.5 40.2 3Mhex 34.8 44.5 46.5 46.2 46.5 47.2 3EPen 19.5 3.5 3.0 3.0 3.1 3.1 Cyclic compound 2.1 0.2 0.6 0.6 1.1 0.8 Decomposition distillation products (%) C ₆ + C ₁ 12.9 11.9 12.0 12.4 14.5 17.0 C ₅ + C ₂ 15.7 20.2 20.6 21.9 21.6 19.1 C ₄ + C ₃ 70.9 65.9 62.0 60.8 59.7 59.9 Etc 0.5 2.0 5.7 4.9 4.2 4.0

This oxycarbide supported on SiC had good solidity (wear resistance, mechanical resistance), good use conditions (no contamination of the reactor), and improved yields in use (a small amount was used for the treated product). .

Example 3

This example illustrates the results obtained using bulk molybdenum oxycarbide modified by the present invention using intermediate oriented oxides obtained in the presence of a humid oxidizing atmosphere. For this purpose, the method of Example 1 was used, in which a humid air stream containing 3% by volume of steam at a rate of 30 cm 3 / min was used instead of the flow of dry air.

After treating for 48 hours, it was converted to oxycarbide to give an oriented oxide which was used for the isomerization of n-heptane as in Example 1.

The results are shown in Table 3 below.

Isomerization of n-heptane in bulk modified molybdenum oxycarbonate prepared from bulk MoO ₃ oriented in the presence of a humid atmosphere Hour 2.75 14.75 19.25 23.25 42 % Conversion 9.9 21.6 21 20.9 20.9 Specific velocity (10 ^-7 molg ^{-1s -1} ) 177.7 362.4 353.7 352.8 352.7 iC ₇ selectivity (%) 88 93 93 93 93 iC ₇ reaction yield (%) 8.7 20.1 19.5 19.4 19.4 Distribution of reaction products % Of C ₆ isomers DMPen 14 13.5 13.3 13.3 13.3 2Mhex 41.5 39.7 39.6 39.6 39.6 3Mhex 40.9 43.1 43.2 43.2 43.2 3EPen 2.7 2.9 2.9 3 2.9 Decomposition distillation products (%) Cyclic compound 0 0.4 0.4 0.5 0.4 C ₆ + C ₁ 5.9 11.3 10.6 11.3 11.2 C ₅ + C ₂ 8.9 10.8 10.9 10.7 10.8 C ₄ + C ₃ 79.5 74.4 74.5 74.8 74.7 Etc 5.6 3.5 4 3.2 3.3

It can be seen that although the specific velocity is lower than when producing oriented Mo oxide in the presence of dry air, the specific velocity is always high. In contrast, the production of oriented oxides requires a much shorter period.

Example 4

In this example, using a bulk modified oxycarbide-based catalyst prepared from a bulk MoO ₃ precursor oriented in the presence of dry air and activated at 6 bar and 350 ° C. in a mixture of n-heptane and hydrogen as in Example 1 The specific rate obtained is compared with the specific rate obtained using a catalyst prepared from a common bulk polycrystalline MoO ₃ and activated under the same conditions.

Specific rates and C ₇ isomeric selectivity obtained with these two catalysts and details of these reaction products are listed in Table 4 below.

Isomerization of n-heptane in bulk modified molybdenum oxycarbide prepared from MoO ₃ and polycrystalline MoO ₃ oriented in the presence of a dry atmosphere Denatured MoO _x C _y Normal MoO _x C _y Hour 2.0 15.5 25.0 2.0 10.0 25.0 % Conversion 2.3 16.2 16.1 26.4 43.0 43.2 Specific velocity (10 ^-7 molg ^{-1s -1} ) 71.0 613.5 608.4 37.3 53.1 53.2 iC ₇ selectivity (%) 95 96 96 93 93 94 iC ₇ reaction yield (%) 2.2 15.6 15.5 24.6 40.0 40.6 Distribution of reaction products % Of C ₆ isomers DMPen 9.5 9.6 9.6 13.3 13.5 13.4 2Mhex 40.4 40.3 40.2 41.4 39.2 39.1 3Mhex 46.4 46.5 46.7 42.4 44.1 44.2 3EPen 3.2 3.1 3.1 2.9 3.2 3.2 Cyclic compound 0.7 0.5 0.5 0 0 0 Decomposition distillation products (%) C ₆ + C ₁ 18 17 16 20 25 25 C ₅ + C ₂ 18 19 13 11 14 16 C ₄ + C ₂ 60 61 67 67 58 56 Etc 4 3 4 2 3 2

The following conclusions were obtained from Table 4.

1. The specific rate for n-heptane isomerization reaction obtained on modified oxycarbide prepared from MoO ₃ oriented by the present invention was much higher than that obtained from the same activity prepared from polycrystalline MoO ₃ (53 × 10). ^-7 mol · g ^-1 · s ^{-1, not, 608 × 10 -7 mol · g} -1 · s -1 Im).

2. The distribution of the reaction product (isomer and cracking distillation) was substantially the same for both catalysts. It can be seen that the active phase formed has the same chemical properties as the so-called molybdenum oxycarbon.

Example 5

The same type of comparison (modified oxycarbide / normal oxycarbide) was performed as in Example 4.

Oxycarbide supported from Si oxide supported on SiC and obtained from polycrystalline MoO ₃ supported on the same SiC with the specific rate (as in Example 3) of the modified Mo oxycarbide denatured in the presence of a humid atmosphere The specific velocity of was compared.

The operating conditions for activation and isomerization of n-heptane are the same as described in Example 4.

The results are shown in Table 5 below.

Isomerization of n-heptane in supported molybdenum oxycarbide prepared from MoO ₃ and polycrystalline MoO ₃ on SiC oriented in the presence of a humid atmosphere MoO _x C _y modified on SiC Conventional MoO _x C _y on SiC Hour 2 5.75 24 2 6 25 % Conversion 10.7 42.3 41.4 13.5 20.2 22.7 Specific velocity (10 ^-7 molg ^{-1s -1} ) 79.7 420.2 421.9 91.5 131.1 146.7 iC ₇ selectivity (%) 85 92 93 94 94 96 iC ₇ reaction yield (%) 9.1 38.9 38.5 12.7 19 21.8 Distribution of reaction products % Of C ₆ isomers DMPen 14.3 13.7 13.1 9.1 10.2 8.8 2Mhex 40.5 40.2 39.7 34.5 41.6 40.5 3Mhex 39.8 42.6 43.5 34.8 44.5 46.5 3EPen 2.7 2.9 3 19.5 3.5 3.1 Decomposition distillation products (%) Cyclic compound 1.8 0.3 0.3 2.1 0.2 1.1 C ₆ + C ₁ 5.3 11 12.5 12.9 11.9 16 C ₅ + C ₂ 7.5 11.5 11.7 15.7 20.2 21.6 C ₄ + C ₃ 81.5 73 71.3 70.9 65.9 59.7 Etc 5.8 4.6 4.5 0.5 2 2.7

It was found that the specific rate obtained using the supported modified oxycarbide was substantially increased compared to the specific rate of the oxycarbide obtained from polycrystalline MoO ₃ .

Example 6

This example illustrates the use of bulky molybdenum oxycarbide modified by the present invention in the hydrogenation and decyclicification of benzene.

In this example, the catalyst of the modified oxycarbide was obtained from the oriented MoO ₃ (wafer form) synthesized in the presence of dry air in Example 1, which was used for hydrogenation and decyclicification of benzene. Reaction temperature and working pressure were 350 ° C. and 60 bar, respectively. The results obtained are shown in Table 6 below. The catalyst was initially activated at 6 bar under a mixture of n-heptane / hydrogen (see Example 3) and then placed under a mixture of benzene / hydrogen at 60 bar.

Hydrogenation of benzene in bulk modified Mo oxycarbide obtained from MoO ₃ after being oriented in the presence of dry air and activated under n-heptane / hydrogen (see Example 3) Hour 2 5 8 22 28 % Conversion 45.5 60.3 70.5 75.0 74.1 iC ₇ selectivity (%) 99 98 97 98 98 iC ₇ reaction yield (%) 45.0 59.1 68.4 73.5 72.6 Distribution of Reaction ProductsC ₆ Product Selectivity (%) Methylcyclopentane 42.4 33.0 24.0 22.8 23.0 Cyclohexane 45.6 55.3 63.8 64.9 64.7 Decyclic reaction 12.0 11.7 12.2 12.3 12.3 Decomposition distillation products (%) C ₆ + C ₁ 49.7 51.0 52.0 51.2 50.0 C ₅ + C ₂ 25.7 26.0 27.0 26.8 27.3 C ₄ + C ₃ 10.0 9.2 10.0 9.6 10.2 Etc 14.6 12.8 11.0 12.4 12.5

From this, two characteristics can be seen.

The selectivity for the C ₆ product is always greater than 97%, so the selectivity is very high.

-Significant degree of decyclization is achieved without decomposition distillation to about 12%. Given that this value is quite high for various reactions and is the most difficult aromatic compound to deprotonate benzene, the catalyst of the present invention may be useful for the decyclicification of aromatic compounds in the purification of oils. will be.

Claims (10)

A modified molybdenum oxycarbonide based catalyst prepared from molybdenum oxide MoO ₃ having a structure comprising a single crystalline wafer oriented in an optional direction. The modified oxymolybdenum catalyst according to claim 1, wherein the specific surface area BET is 5 m 2 / g or more. The modified oxymolybdenum catalyst according to claim 1 or 2, wherein the oxycarbide is supported on a support, and the support is preferably high in specific surface area BET. The modified molybdenum carbide-based catalyst according to claim 3, wherein the support is pure or doped with silicon carbide. Conventional polycrystalline molybdenum oxide or any precursor molybdenum compound converted to oxide is used as a starting material, and such molybdenum oxide is sublimed in a closed space under an oxidizing gas atmosphere at a temperature in the range of 500 ° C to 800 ° C for at least 5 hours. Heat treating by condensation to obtain an oriented recrystallized oxide, which is then treated under a mixture flow of hydrocarbon and hydrogen to obtain modified molybdenum oxycarbide catalyst. The method for producing a modified oxymolybdenum catalyst according to claim 5, wherein the polycrystalline molybdenum oxide or a precursor molybdenum compound of the oxide is mixed with or supported on the support before heat treatment. 7. The process of claim 5 or 6, wherein the oxidizing gas atmosphere is a slow flow rate or a static atmosphere. The method for producing a modified molybdenum oxycarbide catalyst according to any one of claims 5 to 7, wherein the oxidizing gas is dry air or wet air. Use of the oriented molybdenum oxycarbide-based catalyst of any one of claims 1 to 4 as a catalyst in the catalytic reaction of a petrochemical reaction or of the catalyst obtained by the method of any one of claims 5 to 8. Use as a catalyst in catalysis of petrochemical reactions. Use according to claim 9, characterized in that the petrochemical reaction is isomerization and hydrogenation of linear hydrocarbons or cyclic hydrocarbons or decyclicization of aromatic compounds.