METHOD FOR PREPARING A STEAM REFORMING CATALYST, CATALYST AND RELATED USE

Abstract

The present invention addresses to a method of preparing steam reforming catalysts, of the eggshell type, using a solution of glycerin, in polar solvent, preferably water, to occupy the pores of a support. Next, the solvent is removed and the support is impregnated with a nickel salt solution, which may contain promoters such as rare earths. The steps can be repeated until the desired content of the active phase and promoters is reached.

Claims

1. A method of preparing a steam reforming catalyst, characterized in that it comprises the following steps: a) impregnating an inorganic oxide support with a solution of glycerin and polar solvent, at temperatures lower than 90° C. and contact times of less than 1 hour; b) drying the inorganic oxide support of step (a) to remove the solvent, at a temperature between 50° C. and 290° C.; c) impregnating the support obtained in step (b) with a solution containing a nickel salt and optionally promoters, at a temperature between 25° C. and 90° C. and contact times between the nickel solution and the support of less than 1 hour; d) drying the catalyst obtained in step (c) at a temperature of less than 150° C.; e) calcining the catalyst at temperatures between 300° C. and 600° C.; f) optionally, repeating steps c) to e) to obtain the desired content of nickel oxide in the catalyst.

2. The method of preparing a steam reforming catalyst according to claim 1, characterized in that the inorganic oxide support is selected from alpha- or theta-alumina, calcium aluminate, magnesium aluminate, hexa-aluminates or a mixture thereof, which may contain alkali metals.

3. The method of preparing a steam reforming catalyst according to claim 1, characterized in that the promoters are lanthanum, cerium or a combination of these elements.

4. The method of preparing a steam reforming catalyst according to claim 2, characterized in that the shape of the particles of the inorganic oxide support is cylindrical or spherical, containing one or multiple holes, with a smooth or wavy outer surface.

5. The method of preparing a steam reforming catalyst according to claim 4, characterized in that the support particles have diameters and lengths between 10 mm and 25 mm and a surface area between 1 and 100 m.sup.2/g.

6. The method of preparing a steam reforming catalyst according to claim 5, characterized in that the surface area of the support particles is between 10 m.sup.2/g and 80 m.sup.2/g.

7. The method of preparing a steam reforming catalyst according to claim 1, characterized in that the impregnation of the support with glycerin solution (step (a)) can be carried out by the pore volume method or by the excess solution method.

8. The method of preparing a steam reforming catalyst according to claim 1, characterized in that the solvents used for impregnating the support with glycerin in step (a) are polar solvents.

9. The method of preparing a steam reforming catalyst according to claim 8, characterized in that the solvent used to impregnate the support with glycerin in step (a) is water.

10. The method of preparing a steam reforming catalyst according to claim 1, characterized in that, in step (a), the solvent:glycerin ratio is adjusted in order to control the thickness of the active phase on the support.

11. The method of preparing a steam reforming catalyst according to claim 1, characterized in that the drying of the support (step (b)) is carried out at temperatures between 50° C. and 90° C.

12. The method of preparing a steam reforming catalyst according to claim 1, characterized in that the impregnation step with soluble nickel salts (step (c)) uses nickel nitrate.

13. The method of preparing a steam reforming catalyst according to claim 1, characterized in that the impregnation of step (c) occurs at temperatures of up to 90° C., with the contact time between the nickel solution and the support containing glycerin of less than 30 minutes.

14. The method of preparing a steam reforming catalyst according to claim 1, characterized in that the calcination temperature (step (e)) is between 350° C. and 450° C.

15. A catalyst as obtained in claim 1, characterized in that the active phase of nickel oxide and promoters is deposited on the support particle, concentrated on the outer surface or in a small depth layer.

16. The catalyst according to claim 15, characterized in that the thickness of the active phase layer is less than 0.2 mm.

17. A use of the catalyst as obtained in claim 1, characterized in that the catalyst is applicable to the steam reforming reaction or hydrogenation reactions wherever the active phase of metallic nickel is necessary.

18. The method of preparing a steam reforming catalyst according to claim 8, characterized in that the polar solvents comprise methanol, ethanol or water.

19. The method of preparing a steam reforming catalyst according to claim 10, characterized in that, in step (a), the solvent:glycerin ratio is adjusted from 10:90 to 20:80 v/v.

20. The catalyst according to claim 16, characterized in that the thickness of the active phase layer is less than 0.1 mm.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0024] The present invention will be described in more detail below, with reference to FIGS. 1 to 8 which, in a schematic way and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:

[0025] FIG. 1 illustrating a NiO/magnesium aluminate catalyst, prepared according to Example 1, using prior impregnation of the support with water and nickel acetate aqueous solution. The darker color indicates the presence of nickel oxide;

[0026] FIG. 2 illustrating a NiO/magnesium aluminate catalyst, prepared according to Example 2, using prior impregnation of the support with water and nickel nitrate aqueous solution. The darker color indicates the presence of nickel oxide;

[0027] FIG. 3 illustrating a NiO/magnesium aluminate catalyst, prepared according to Example 3, using prior impregnation of the support with n-heptane and nickel nitrate aqueous solution. The darker color indicates the presence of nickel oxide;

[0028] FIG. 4 illustrating a NiO/magnesium aluminate catalyst, prepared according to Example 3 (top), Example 4 (middle) and Example 5 (bottom), using prior impregnation of the support with glycerin aqueous solution and nickel nitrate aqueous solution. The darker color indicates the presence of nickel oxide;

[0029] FIG. 5 illustrating a NiO/magnesium aluminate catalyst, prepared according to Example 5, using prior impregnation of the support with glycerin aqueous solution and nickel nitrate aqueous solution. The darker color indicates the presence of nickel oxide;

[0030] FIG. 6 illustrating a NiO/magnesium aluminate catalyst, prepared according to Example 8, using prior impregnation of the support with ethylene glycol aqueous solution and nickel nitrate aqueous solution. The darker color indicates the presence of nickel oxide;

[0031] FIG. 7 illustrating a NiO/magnesium aluminate catalyst, prepared according to Example 9, using prior impregnation of the support with ethanol and glycerin solution and nickel nitrate solution in ethanol. The darker color indicates the presence of nickel oxide;

[0032] FIG. 8 illustrating a NiO-La.sub.2O.sub.3/magnesium aluminate catalyst, prepared according to Example 10, using prior impregnation of the support with glycerin aqueous solution and aqueous solution of nickel and lanthanum nitrate. The darker color indicates the presence of nickel oxide;

[0033] FIG. 9 compares the coke deposition resistance of the catalyst prepared according to Example 6 of the present invention and commercial natural gas and naphtha steam reforming catalysts.

DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention addresses to a method of preparing a catalyst applicable to the steam reforming reaction where the active phase containing nickel is located in the outer layer of the particle or with a thickness of less than 0.2 mm, preferably less than 0.1 mm.

[0035] The adopted solution was a method of preparing a catalyst comprising the following steps: [0036] a) impregnating an inorganic oxide support with a solution of glycerin and water; [0037] b) drying the inorganic oxide support to remove water; [0038] c) impregnating the glycerin-containing support with a solution containing a nickel soluble salt, preferably nickel nitrate; [0039] d) drying the nickel salt impregnated support; [0040] e) calcining the nickel salt impregnated support to transform this salt into a nickel oxide layer located on the surface or at a small depth of the support; [0041] f) optionally, repeating steps c) to e) to obtain the desired content of nickel oxide.

[0042] The inorganic oxide support is selected from the group consisting of alpha- or theta-alumina, calcium aluminate, magnesium aluminate, hexa-aluminates, rare earth oxide or mixtures thereof, and may contain alkali metals, preferably potassium, in contents of up to 10% m/m. The support can have different shapes such as cylinders or spheres containing one or multiple holes, and its outer surface can be smooth or preferably wavy, to increase the outer area. The diameter and length of the support particles are between 10 mm and 25 mm. Preferably, the support has a surface area (measured by the nitrogen adsorption technique) between 1 and 100 m.sup.2/g, preferably between 10 m.sup.2/g and 80 m.sup.2/g.

[0043] The impregnation of the support with the glycerin and water solution can be carried out by the pore volume methods or, preferably, by the excess solution method. In the preferred method, the support particles are immersed in the glycerin and water solution at temperatures below 90° C., preferably at room temperature, for a period of time sufficient for the solution to penetrate the interior of the particles. Typically, 10 minutes are sufficient for this purpose, but longer times can be used, when necessary. Water is the preferred solvent for glycerin solution because of its low cost and high miscibility with glycerin. Other polar solvents, like alcohols, such as methanol or ethanol, can also be used, when there is some degradation of the support in the presence of water or when it is advantageous to use a solvent with a boiling point lower than that of water to reduce the costs of the steps of drying.

[0044] The proportion of solvent, preferably water, in the glycerin solution is chosen in order to control the penetration of the nickel oxide phase into the support particle. As an example, a solution containing 10% water and 90% glycerin is used when it is desired that only 10% of the pore volume of the support is available for later occupation with the nickel solution. This available volume will be located close to the surface of the particles, while the interior of the particles will remain occupied by glycerin. In this way, after the subsequent steps of impregnation with the solution containing nickel salt, drying and calcination, a layer of nickel oxide will preferably be formed in the space previously occupied by water, covering the surface of the particle and with controlled thickness. The thickness of the nickel oxide layer is less than 0.2 mm, preferably less than 0.1 mm.

[0045] The drying of the inorganic oxide support containing the glycerin and water solution must be carried out in order to remove the water and preserve the glycerin phase inside the support particles; for this purpose, temperatures between 50° C. and 90° C. are preferable, as they allow a slow and gradual removal of water without dragging the glycerin phase. Drying temperatures above 100° C. can cause rapid water vaporization (and drag of the glycerin phase), in addition to favoring the breakage or reduction of the mechanical strength of the support particles. The maximum drying temperature must be below the boiling point of glycerin at 290° C.

[0046] The impregnation of the support containing glycerin with the nickel salt solution can be carried out by the impregnation technique of the pore volume or preferably by the technique of excess solution. Water is preferably used as a solvent because of its low cost and high solubility of nickel salts. Other polar solvents, like alcohols, such as methanol or ethanol, can also be used, if there is any degradation of the support in an aqueous medium. The preferred nickel salt is nitrate, such as Ni(NO.sub.3).sub.3.6H.sub.2O, due to its low cost and high water solubility. The impregnation can be carried out at room temperature or preferably at temperatures up to 90° C. to increase the solubility of nickel nitrate and, consequently, reduce the number of repetitions of the steps necessary to obtain the desired content of nickel oxide in the support. The contact times between the nickel solution and the support containing glycerin are less than 1 hour, preferably less than 30 minutes and more preferably less than 5 minutes, considering aspects of increasing the productivity of the process. However, times longer than 1 hour can be used, when industrially necessary for reasons of logistics, type or handling of equipment, without losing the formation of the surface layer of nickel oxide. Several promoters can be added to the nickel salt solution in order to increase the activity or the resistance to coke deposition in the H2 production process by steam reforming, being preferable the addition of rare earth elements, such as lanthanum and cerium, or other elements such as copper or noble metals.

[0047] The drying of the support can be carried out preferably at temperatures lower than 90° C., with no limitation as to drying the material at temperatures below the melting temperature of the salts, such as nickel nitrate. The calcination for the decomposition of the nickel precursor salts and the formation of the nickel oxide layer is carried out between 300° C. and 600° C., preferably between 350° C. and 450° C.

[0048] The method does not require pH control, or the addition of complexing agents or the use of specific nickel salts, such as acetates, to control the interaction between the charges of the metallic cations and the surface of the support, in order to obtain the nickel oxide layer on the surface of the support particles.

[0049] The catalyst thus prepared will be in the form of nickel oxide deposited on a refractory support and, for use in reactions where an active phase of metallic nickel is required, such as in hydrogenation or steam reforming reactions, it is necessary to carry out a reduction procedure, which can preferably be carried out “in-situ”, that is, inside the industrial reactor. For the steam reforming process, the “in-situ” reduction is preferably carried out by passing hydrogen and steam or natural gas and steam, in the molar ratios of steam/H.sub.2 or steam/C between 6 and 8 mol/mol at temperatures above 400° C., preferably above 550° C., at the inlet of the process gases in the tubes of the primary reformer, and between 700° C. and 900° C. at the outlet of the process gases from the tubes of the primary reformer. The pressure to be used during the reduction is limited by the metallurgy of the tubes or by equipment such as compressors, in general, pressures between 5 and 15 kgf/cm.sup.2 (0.49 and 1,47 MPa) are typically used in the reduction step. The natural gas used in this way must be free of sulfur and olefins (<0.1% v/v). In another understanding, catalysts can be reduced externally to the unit using hydrogen or hydrogen-rich gases and then passivated with mixtures, preferably less than 5% v/v oxygen, air or carbon dioxide in nitrogen. When the passivation process is carried out at temperatures below 50° C., natural gas can be used as an inert gas.

[0050] The catalyst thus prepared has preferential application in reactions where there are restrictions on mass transfer within the support particles, such as occurs, due to the high temperatures of the process, in the steps of primary reform, secondary reform and to a lesser extent in the pre-reforming step of the steam reforming process for the production of hydrogen or hydrogen-rich gases and in liquid-phase hydrogenation reactions.

EXAMPLES

[0051] The following examples are presented in order to illustrate the nature of the present invention and the manner of practicing the same, without, however, being considered as limiting its content.

Example 1

[0052] This example illustrates the preparation of a catalyst containing nickel oxide, using nickel acetate and a commercial support. Ten grams of a magnesium aluminate-type support (DYTECH, Ceraguard 1616, with dimensions of 16×16×7 mm, in the shape of a ring with 6 holes) were broken into smaller pieces. The support was then immersed in deionized water for 10 minutes, drained and weighed, obtaining a content of 0.27 g of water/g of support. Then, the material was partially dried at 70° C. for 30 minutes, the water content being reduced to 0.19 g of water/g of support, and then immersed and kept for 10 minutes in an aqueous solution containing 20 g of tetrahydrate nickel acetate (C.sub.4H.sub.6NiO.sub.4.4H.sub.2O) in 200 g of water. Then the material was separated from the solution, dried at 100° C. for 1 hour and calcined at 400° C. for 1 hour, obtaining a distribution of the nickel oxide phase with eggshell predominance, as can be seen in FIG. 1.

Example 2

[0053] This example illustrates that the use of nickel nitrate does not allow to obtain an eggshell distribution of the nickel oxide phase, when the catalyst is prepared according to the state of the art. The preparation was carried out in a similar way to EXAMPLE 1, except that, in the immersion step of the pellets in the aqueous solution of nickel salt, a solution of nickel nitrate (Ni(NO.sub.3).sub.2.6H.sub.2O) at 70% m/m was used. The final catalyst showed a distribution of nickel oxide inside the particle, as illustrated in FIG. 2. Alterations to the method were tested, but the eggshell distribution was not obtained in any of the variations: a) use of a contact time of 3 minutes; b) use of temperatures at 200° C. in the drying step and direct placement of the wet samples in the oven at 400° C. In this last condition, there were still technical problems related to the breakage and projection of the samples due to the sudden loss of moisture and generation of gases. The final product showed distribution of NiO along the entire particle, showing the difficulty of using nickel nitrate to prepare eggshell catalysts by the technique described in the state of the art.

Example 3

[0054] This example, according to the state of the art, illustrates that the previous impregnation of the support with non-polar hydrocarbons and the subsequent immersion in an aqueous solution of nickel nitrate favors a homogeneous distribution of the nickel oxide phase, not obtaining the desired eggshell distribution. Ten grams of a magnesium aluminate-type support (DYTECH, Ceraguard 1616, with dimensions of 16×16×7 mm, in the shape of a ring with 6 holes) were broken into smaller pieces. The support was then immersed in n-heptane for 10 minutes, drained and weighed and partially dried at 70° C. for 3 minutes, obtaining a content of n-heptane inside the particles of 0.20 mL/g. Next, the material was immersed and maintained for 10 minutes in an aqueous solution of 80% m/m of nickel nitrate (Ni(NO.sub.3).sub.2.6H.sub.2O). Next, the material was separated from the solution, dried at 100° C. for 1 hour and calcined at 400° C. for 1 hour, obtaining a distribution of the nickel oxide phase inside the particles, as shown in FIG. 3, even for a contact time with the nickel nitrate solution as short as 3 minutes.

Example 4

[0055] This example, according to the present invention, illustrates the preparation of a catalyst containing nickel oxide located predominantly on the surface or in a layer close to the surface of a preformed support. One hundred grams of a magnesium aluminate-type support (DYTEC, Ceraguard 1616, with dimensions of 16×16×7 mm in the shape of a ring with 6 holes), without being previously dried, were immersed in a solution containing 80% glycerin and 20% water, at room temperature (25° C.) for 10 minutes, followed by gravity drainage and drying at 70° C. for 2 hours to remove the water. Next, the pellets were immersed for 20 minutes in an aqueous solution containing 70% m/m nickel nitrate (Ni(NO.sub.3).sub.2.6H.sub.2O) at room temperature. The material was next gravity drained, dried at 70° C. for 2 hours and calcined with a temperature scheduling from 70° C. to 400° C. at a rate of 10° C./min. The temperature of 400° C. was maintained for 2 hours. The pellets were broken for visual inspection, which showed the predominance of the nickel oxide phase on the surface of the particles, as illustrated in FIG. 4.

Example 5

[0056] This example was carried out as described in Example 4, with the difference that the procedure was repeated 2 times to increase the content of incorporated nickel oxide. The pellets were broken for visual inspection, which showed the predominance of the nickel oxide phase on the surface of the particles, as illustrated in FIG. 4.

Example 6

[0057] This example was carried out as described in Example 4, with the difference that the procedure was repeated 3 times to increase the content of nickel oxide incorporated. The pellets were broken for visual inspection, which showed the predominance of the nickel oxide phase on the surface of the particles, as seen in FIG. 4.

Example 7

[0058] This example, according to the present invention, illustrates that contact times greater than 1 hour, between the support previously impregnated with the glycerin solution and the aqueous solution of nickel nitrate, do not affect the distribution of the oxide layer nickel, which remains predominantly on or near the surface. The pellets were broken for visual inspection, which confirmed the predominance of the nickel oxide phase on the surface of the particles, as shown in FIG. 5, for all tested contact times.

Example 8

[0059] This example illustrates that ethylene glycol cannot replace glycerin in the present invention, despite its physicochemical proximity, that is, it is not enough to be a polar hydrocarbon. Ten grams of a magnesium aluminate-type support (DYTECH, Ceraguard 1616, with dimensions of 16×16×7 mm, in the shape of a ring with 6 holes) were broken into smaller pieces. The support was then immersed in an ethylene glycol solution (70% m/m) and water for 10 minutes, drained and dried at 70° C. for 30 minutes. Next, the support was immersed in an aqueous solution containing 70% m/m of nickel nitrate (Ni(NO.sub.3).sub.2.6H.sub.2O), at room temperature for periods between 3 minutes and 1 hour. Next, the material was separated from the solution, dried at 100° C. for 1 hour and calcined at 400° C. for 1 hour. The final catalyst showed a distribution of nickel oxide inside the particle, as seen in FIG. 6, for all tested contact times.

Example 9

[0060] This example, according to the present invention, illustrates the preparation of a catalyst containing nickel oxide located predominantly on the surface or in a layer close to the surface of a commercial support, replacing the water in the solutions with ethanol. One hundred grams of a magnesium aluminate-type support (DYTEC, Ceraguard 1616, with dimensions of 16×16×7 mm in the shape of a ring with 6 holes), without being previously dried, were immersed in a solution containing 80% glycerin and 20% ethanol, at room temperature (25° C.) for 10 minutes, followed by gravity drainage and drying at 70° C. for 2 hours to remove the ethanol. Next, the pellets were immersed for 20 minutes in a solution containing 70% m/m of nickel nitrate (Ni(NO.sub.3).sub.2.6H.sub.2O) in ethanol at room temperature. The material was then gravity drained, dried at 70° C. for 2 hours and calcined with a temperature scheduling from 70° C. to 400° C. at a rate of 10° C./min. The temperature of 400° C. was maintained for 2 hours. The pellets were broken for visual inspection, which showed the predominance of the nickel oxide phase on the surface of the particles, as illustrated in FIG. 7.

Example 10

[0061] This example, according to the present invention, illustrates the use of salts based on nitrates for the preparation of a catalyst containing nickel oxide and promoted by lanthanum. One hundred grams of a magnesium aluminate-type support (DYTEC, Ceraguard 1616, with dimensions of 16×16×7 mm in the shape of a ring with 6 holes), without being previously dried, were immersed in a solution containing 80% glycerin and 20% water, at room temperature (25° C.) for 10 minutes, followed by gravity drainage and drying at 70° C. for 2 hours to remove the water. Next, the pellets were immersed for 60 minutes in an aqueous solution containing 210 g of nickel nitrate (Ni(NO.sub.3).sub.2.6H.sub.2O), 32 g of lanthanum nitrate (La(NO.sub.3).sub.3.6H.sub.2O and 90 g of water at 50° C. The material was gravity drained, dried at 70° C. for 2 hours and calcined with a temperature scheduling from 70° C. to 400° C. at a rate of 10° C./min. The temperature of 400° C. was maintained for 2 hours. The pellets were broken for visual inspection, which showed the predominance of the nickel oxide phase on the surface of the particles, as illustrated in FIG. 8.

Example 11

[0062] This comparative example, according to the state of the art, shows the preparation of a conventional catalyst, that is, with predominantly homogeneous distribution along the particle. Preparation was carried out in a similar manner to Example 4, except that glycerin was not used. One hundred grams of a magnesium aluminate-type support (DYTEC, Ceraguard 1616, with dimensions of 16×16×7 mm in the shape of a ring with 6 holes), without being previously dried, were immersed in water at room temperature (25° C.) for 10 minutes, followed by gravity drainage and drying at 70° C. for 2 hours to remove the water. Next, the pellets were immersed for 20 minutes in an aqueous solution containing 70% m/m of nickel nitrate (Ni(NO.sub.3).sub.2.6H.sub.2O) at room temperature. The material was then gravity drained, dried at 70° C. for 2 hours and calcined with a temperature scheduling from 70° C. to 400° C. at a rate of 10° C./min. The temperature of 400° C. was maintained for 2 hours. The pellets were broken for visual inspection, which showed the predominance of the nickel oxide phase on the surface of the particles, as shown in FIG. 4.

Example 12

[0063] This example illustrates the use of the catalyst of the present invention for the steam reforming reaction. The activity of the catalysts was experimentally determined in a commercial equipment AutoChem II (Micrometrics). The tests were performed using 200 mg of the solid, in a range smaller than 170 mesh, obtained by scraping the outer surface of the samples. Initially, an activation (reduction) step was carried out at a temperature of 750° C., at atmospheric pressure, for two hours, by passing 40 mL/min of a mixture containing 10% H.sub.2/argon saturated with water vapor at 50° C. over the catalyst. After the activation, the methane steam reforming reaction was carried out, by passing a stream of methane (99.99%) saturated in water vapor at 90° C., which corresponds to a steam/carbon ratio of 2.3 mol/mol, at reaction temperatures of 500° C., 550° C. and 600° C., respectively. The effluent gases from the reactor were analyzed by gas chromatography and the activity measured by the degree of methane conversion.

[0064] Table 1 presents the results of the catalytic activity of steam reforming of methane at different temperatures, and it can be observed that: a) the catalysts according to the present invention show superior activity to the materials prepared according to the state of the art (comparison of Example 2 with the other examples in Table 1), with the additional advantage of having a lower NiO content/product mass; b) the activity of the catalyst of the present invention can be adjusted by the number of preparation steps, without losing the nature of the eggshell distribution of the nickel phase (comparison between Examples 4, 5 and 6 of Table 1); and c) the developed method allows the use of promoters, such as lanthanum, which allow an even higher activity to be obtained, while maintaining the eggshell distribution (comparison of Examples 5 and 10).

TABLE-US-00001 TABLE 1 Catalytic Activity T = T = T = Example Type 500° C. 550° C. 600° C. 2 Magnesium Ni-aluminate 20.0 28.0 34.0 (1 step) 4 Magnesium Ni-aluminate 24.0 34.0 41.0 (1 step) 5 Magnesium Ni-aluminate 27.0 36.0 44.0 (2 steps) 6 Magnesium Ni-aluminate 34.0 46.0 52.0 (3 steps) 10 Magnesium Ni-La- 33.0 44.0 48.0 aluminate (2 steps)

Example 13

[0065] This example illustrates that the catalysts prepared according to the present invention have resistance to coke deposition superior to those prepared according to prior art, making them especially suitable for use in the production of hydrogen by the steam reforming reaction. The procedure for measuring the resistance of coke deposition consisted of: a) reducing the catalysts in H.sub.2 flow at 700° C. for 2 h to obtain the active phase of metallic nickel; b) carrying out the CH.sub.4 steam reforming reaction at a temperature of 600° C., atmospheric pressure and a steam/carbon ratio of 0.01 mol/mol for 15 minutes for the deposition of coke; c) reducing the reactor temperature in N2 flow to 350° C.; d) carrying out the combustion of the deposited coke in a synthetic air flow, with temperature scheduling from 350° C. to 650° C. at a rate of 150° C./h, following the evolution of CO.sub.2 by mass spectrometry. A lower evolution of CO.sub.2 indicates a lower content of deposited coke, that is, a greater resistance of the catalyst to coke deposition.

[0066] The more resistant, more active and robust catalysts contribute to the reduction of the risk of the appearance of high temperature regions of the wall of the tubes of the reformer of the hydrogen production process. Such a situation tends to reduce the useful life of the tubes with the risk of unscheduled shutdowns of the unit and personal risks.

[0067] The steam reforming catalyst is the essential part of the H.sub.2 generation process. Its performance affects the entire unit. The higher the catalyst activity, the lower the temperature of the reformer tubes, allowing them to operate in less severe conditions and, therefore, with greater potential to reach the expected campaign.

[0068] More active steam reforming catalysts provide a reduction in the fuel used in the H.sub.2 production process, with a consequent reduction in CO.sub.2 emissions. The invention also allows a use for glycerin, which is a by-product of the biodiesel production process.

[0069] It should be noted that, although the present invention has been described in relation to the attached drawings, it may undergo modifications and adaptations by technicians skilled on the subject, depending on the specific situation, but provided that it is within the inventive scope defined herein.