WO2010060736A1

WO2010060736A1 - Non-noble metals based catalysts for ammonia decomposition and their preparation

Info

Publication number: WO2010060736A1
Application number: PCT/EP2009/064425
Authority: WO
Inventors: Claudiu Constantin Pavel; Massimiliano Comotti; Chiara Emiliani; Adriana Scaffidi
Original assignee: Acta S.P.A.
Priority date: 2008-11-03
Filing date: 2009-11-02
Publication date: 2010-06-03
Also published as: ITFI20080210A1

Abstract

The present invention relates to catalysts based on non precious metal nanoparticles, their oxides or mixture thereof supported onto inorganic materials obtained via a process including several steps, which might be divided into (a) support preparation and (b) deposition of the active phase. The catalysts described in the present invention are active in the ammonia decomposition reaction for producing hydrogen.

Description

Non-noble metals based catalysts for ammonia decomposition and their preparation

FIELD OF THE INVENTION The present invention refers to the non-noble metals based catalysts, in particular to their preparation and use for decomposition of ammonia.

STATE OF THE ART

Recent European and International directives are making even more stringent regulations for the emissions of carbon dioxide generated from production activities and automotive sector, stimulating, where possible, the trapping and/or the conversion of the already existing carbon dioxide. From this point of view, ammonia, as naturally free of carbon, is presented as the most viable alternative to traditional fuels used so far. The catalysts described in this patent have been designed in such a way that they can be used within internal combustion engines (ICE) operating with mixtures Hydrogen/Ammonia. In fact in the literature is reported that from a theoretical point of view an internal combustion engine fueled by ammonia is more efficient than one running with gasoline. However, in practice it is requested the presence of hydrogen as an additive in various amounts from 2.5 to 5 % (N. Arora et al., Metals and Mineral Review, (1970) 17). A first step in this direction was attempted by Hydrogen Energy Center (USA), using hydrogen stored in tanks assembled onto the vehicle, but these are unpractical from the dimension and security point of view. To overcome the technological problems associated to hydrogen storage, the Applicant has made catalysts that can generate hydrogen in-situ by decomposition of ammonia. In this case, ammonia works both as a carrier for on-demand production of hydrogen, and as co-fuel in internal combustion engines. One of the advantages associated with the use of ammonia is its availability both from degradation processes of organic waste and from direct synthesis, and its density that allows, for the same volume of gas, to contain more hydrogen than pure H₂ gas, providing an effective intermediate for hydrogen storage that does not require the drastic conditions of pressure and temperature demanded by pure hydrogen storage. Furthermore, while the large scale employment of hydrogen powered vehicles would require a drastic change in the local distribution network to adequate it to the security parameters required for the storage of such material, ammonia can be transported more easily, and in some countries such as USA it is already widely distributed to be used as fertilizer. Moreover, when new technologies for providing hydrogen from renewable sources will become available, since the efficiency of conversion process from hydrogen to ammonia is about 90 %, this technique would make an advantageous solution in terms of hydrogen storage.

Processes involving the decomposition of ammonia are described in both patent (e.g. WO98/4031 1 A1 ) and scientific literature (CH. Christensen et al., "Towards an ammonia-mediated hydrogen economy?", Cat. Today 1 1 1 (2006) 140). However, this process requires the use of precious metals such as platinum, iridium or ruthenium (see e.g. Yin et al., App. Cat. A: General 301 (2006) 202, or Pilecka et al., J. Catal., 218 (2003) 465). The main problem with the use of precious metals as active phase for catalyst preparation on the large scale, such as in automotive, is their high cost and low natural abundance. In fact, the natural reserves of precious metals would be enough to cover the world demand for just a few years and the prices are totally unsustainable, especially for emerging countries such as India or China.

The State of the Art highlights that in recent years a study aimed to preparation of catalysts for the thermal oxidation of ammonia using non-precious metals such as iron or nickel has been started. For example, ltoh et al., Material Transaction, 43 (2002) 2763, describes the use of high iron loadings co-precipitated on cerium oxide as promoter for the ammonia reforming reaction. However, this catalyst shows catalytic activity only at low space velocity, thus not exhibiting the activity necessary to produce the hydrogen required by an operating internal combustion engine. In the case of EP1872852A1 patent the catalyst is active in the temperature range 300 - 350 °C. However, these catalysts contains together with non-noble metals such as copper also small amounts of platinum, thus not showing its ability to perform the reforming of ammonia using only metals easily available. Furthermore, the amount of ammonia treated is very small (1 wt.% in air) and is not guaranteed the possibility to treat larger amounts as required by an internal combustion engine. Moreover in this case the reaction of ammonia decomposition has not place, but rather its oxidation in air. It is therefore evident the need of catalysts based on non-noble metals that are capable of promoting the decomposition of ammonia.

BRIEF DESCRIPTION OF FIGURES

Figure 1 - shows conversion values as a function of temperature for decomposition of ammonia, using some of the catalysts of this invention compared to the commercial catalyst G90-B (Sϋd Chemie)

Figure. 2 - shows for some catalysts of the invention the influence of polymer loading on the support surface area and activity for ammonia decomposition at

500 °C

DETAILED DESCRIPTION OF INVENTION

The present invention relates to nanoparticled catalysts based on non-noble metals or their corresponding oxides or mixture thereof supported on a porous inorganic material obtained by a process comprising the following steps: i. preparation of the support by coating the porous inorganic material with an organic material and subsequent pyrolysis; ii. deposition onto the support of ions of the above mentioned non-noble metals by impregnation and subsequent reducing or oxidizing thermal treatment, depending on the required active metal phase metal form with the zero oxidation grade, or metal oxides or mixture thereof.

These non-noble metals or metal oxides are selected from the first series of transition metals, preferable Fe, Co and Ni and/or their mixtures and/or alloys.

Said porous inorganic material is selected from metal oxides or their mixtures such as AI₂O₃, ZrO₂, CeO_x, MgO, MgAI₂O₄, La₂O₃, SiO₂, Y₂O₃; preferably AI₂O₃, ZrO₂, CeOx, MgO or MgAI₂O₄ (which have been proved to be some of the most active for these catalysts) eventually enriched with doping amounts of promoters such as

La₂O₃, SiO₂, Y₂O₃ (in order to improve the catalytic activity). Preparation of the support able to activate and promote the catalytic activity for catalytic decomposition of ammonia consists in covering fine particles of metal oxides (the porous inorganic material) by impregnation (or combination in various forms of some metal oxides) with a nano-structured organic material comprising carbon, nitrogen and oxygen, at least two aromatic or heteroaromatic groups and at least one conjugated double bond, in order to arrange the organic coating, through intra- and intermolecular binding bond in a structure very rigid and stable. The subsequent pyrolysis of the nano-structured organic material impregnated on the surface of the small particles of inorganic support leads to the formation of a well organized microporosity in which can be adsorbed the metal salts, that during the reduction/oxidation processes become nanoparticles with a particular catalytic activity. As an organic material for the purposes of the present invention it is intended preferably a compound with formula (A)

where R1 is chosen from the group consisting of: H and a hydrocarbon radical having from 1 to 10 carbon atoms, possible halogenated, R2 and R3 independently represent preferentially a electron-attractor group consisting of hydrogen, halogen, acyl, ester, carboxylic acid, formyl, nitrile, sulfonic acid, aryl groups, linear or branched alkyl groups having 1 to 15 carbon atoms possible functionalized with halogens or linked together to form one or more condensed cycles with phenyl ring and nitro groups or a polymer selected from those described in WO2004/036674A2 represented by the formula (C)

(C)

where, y can vary between 2 and 120; x can be 1 or 2, n can vary between 1 and 3, and R₁, R₂, R₃ are defined as above, and R₄ and R₅ independently represent a electron-donor group chosen from a group containing H, OH, ether, amines, aryl and alkyl, linear or branched groups, having from 1 to 15 carbon atoms. The coating of an inorganic support with an organic material can be done using classic impregnation methods (e.g. wet or incipient wetness) at a temperature comprised between 20 and 90 °C, according to the solvent and to the pressure used to dissolve the organic material. As solvent, depending on the concentration and the solubility of the organic matrix, can be used for example water, alcohols, aldehydes and/or ketones or other solvents that are efficient for such purpose. Preferibly the solvents used in this phase of the process are water, at a pH comprised between 9 and 12, or ethanol, acetone, DMF, DMSO. Once the complete impregnation of the metal oxide by the organic material is obtained, the solid obtained by solvent removal and drying is thermally treated in inert atmosphere at a temperature comprised between 400 and 1000 °C. Such thermal process promotes the carbonization of the organic component, nonetheless maintaining almost unchanged the tridimensional structure of the outer layer. In such way it is possible to obtain a considerable increase of the surface area and of the microporosity of the support.

It had been observed that the ratio between the organic material and inorganic support play a fundamental role, inducing very important and substantial structural modifications in the obtained composite materials, especially related to surface area and porosity of the support (see Table 2). The investigations regarding catalyst composition pointed out that the amount of organic material used to coat the inorganic support and thus the ratio between organic material and inorganic support could advantageously be varied between 0.5:1 and 2:1 in weight, but more preferably between 0.75:1 and 1.5:1 in weight. Once obtained a highly porous and nanostructured support, the following synthetic step consists in the deposition of active metal ions, from non-noble metals, by classic impregnation methods (e.g. wet or incipient wetness) at a temperature comprised between 20 and 90 °C, according to the solvent and to the pressure. Once obtained the deposition of the metallic precursors inside the porous nanostructured support, it is necessary to make a thermal treatment that requires, depending which chemical nature of the metallic particle is needed (metal with zero valence or metal oxide, or a mixture of them), a reduction with hydrogen (pure or diluted with another inert gas) or a calcination with oxygen (pure or diluted with another inert gas). Such thermal treatment can be carried on at a temperature comprised between 300 and 1000 °C, obtaining a total metal loading in the final product comprised between 5 and 50 wt% of total catalyst weight. After these thermal treatments the surface area of the so obtained catalyst can be comprised between 30 and 350 m² g^"1. Moreover, it has to be pointed out that during the thermal treatment the catalyst undergoes to structural and chemical modifications, which trigger processes devoted to increase stability of the resultant material when exposed to reaction conditions (see example 10 and Table 3).

In case the catalyst contain more than one active metal ion, the deposition process can be carried out either in one (by means of co-impregnation) or multiple steps (by means of consecutive impregnations). In the latter case, each impregnation is alternated with a thermal treatment.

In a non limiting example the composite support can be firstly impregnated with an iron salt solution and then thermally treated at a temperature T₁. The resultant solid can be then impregnated with a cobalt salt solution and again thermally treated at a temperature T₂ in order to obtain the final material formulation. Such thermal treatments can be either oxidative or reductive, depending on desired product. Temperatures values T₁ and T₂ might be equal or different depending from the case and comprised between 300 and 1000 °C. In fact, it has been found that in some cases consecutive impregnations might drive to different nanoparticles composition and morphology (e.g. core-shell type or alloy nanoparticles), with different activities for the ammonia decomposition reaction. Catalyst stability under ammonia stream at high temperature was also found to be influenced from this aspect.

The precursor of said non-noble active metals can be salts such as acetates, halides, nitrates, carbonates, bicarbonates, sulfates, oxides, malonates, and analogous organic salts and their mixtures. Optionally, the catalyst composition can be doped with other elements which could be considered as promoters, able to increase both structural stability and catalytic activity. The addition of such elements, typically belonging to the alkaline, earth- alkaline and lanthanides gruops of the periodic table, and in particular but not limited to Cs, K, Ba, Mg, Y, Ce and La, can be performed by classic impregnation methods (e.g. wet or incipient wetness) at a temperature comprised between 20 and 90 °C, according to the solvent and to the pressure employed. The addition of such elements can be performed at any step of the catalyst preparation process, but preferably it is performed after the nanostructured support has been prepared. The promoter to non noble metal(s) ratio can be varied in the range 2-0.01 taking into account the complete amount of non noble metal(s) composing the end product. After the addition of the promoter precursor the material can undergoes either to a thermal treatment (which could be either performed under oxidative or reducing atmosphere) or to an another impregnation step. The precursor of said promoters can be salts such as nitrates, sulfates, bromides, carbonates, chlorides, fluorides, iodides, oxalates, hydroxides, perchlorates, and phosphates.

The catalysts of this inventions are useful for ammonia decomposition; thus object of the invention is a method for producing hydrogen from ammonia, said method wherein a catalyst as described above is used. Catalysts of the invention as described above can be used in devices for ammonia reforming. Thus further object of the present invention are ammonia reformers comprising at least a catalyst as above described.

Further object of the invention are hydrogen powered systems, such as internal combustion engine fueled by hydrogen/ammonia mixtures as well as fuel cells, said systems comprising at least an ammonia reformer as described above, or wherein the necessary hydrogen is produced by the method above.

The present described invention could be better understood in view of the following examples.

EXAMPLE 1 : Preparation of a "Catalyst A"

In a 250 ml_ flask 5 g of γ-AI₂O₃ (Sasol) or alumina (Disperal 40, Sasol), 7 g of polymer (as described in WO2004/036674A2, Example 1 ), 7 g of ammonium nitrate and 150 ml_ of distilled water were added. A 30 wt% ammonia solution was added dropwise till the pH of the solution was 9. The suspension was then heated up to 50 °C and left stirring for 8 h. At this point, the solvent was removed via vacuum evaporation, and the obtained solid was dried in oven at 70 °C overnight. The dried material was thus pyrolyzed in argon flow at 900 °C for 2 h (heating rate from room temperature: 10 °C min^"1). 0.9 g of the composite material obtained as reported above are impregnated via incipient wetness with a aqueous solution containing 0.31 g of Iron (II) acetate in order to obtain a 10 wt %. final metal load. After impregnation the material is dried in oven at 70 °C and finally reduced in hydrogen flow at 500 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

EXAMPLE 2: Preparation of a "Catalyst B"

In a 250 mL flask 5 g of γ-AI₂O₃ (Sasol) or alumina (Disperal 40, Sasol), 7 g of polymer (as described in WO2004/036674A2, Example 1 ), 7 g of ammonium nitrate and 150 mL of distilled water were added. A 30 wt% ammonia solution was added dropwise till the pH of the solution was 9. The suspension was then heated up to 50 °C and left stirring for 8 h. At this point, the solvent was removed via vacuum evaporation, and the obtained solid was dried in oven at 70 °C overnight. The dried material was thus pyrolyzed in argon flow at 900 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

0.9 g of the composite material obtained as reported above are impregnated via incipient wetness with a aqueous solution containing 0.42 g of Nichel (II) acetate in order to obtain a 10 wt %. final metal load. After impregnation the material is dried in oven at 70 °C and finally reduced in hydrogen flow at 500 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

EXAMPLE 3: Preparation of a "Catalyst C" In a 250 ml_ flask 5 g of γ-AI₂O₃ (Sasol) or alumina (Disperal 40, Sasol), 7 g of polymer (as described in WO2004/036674A2, Example 1 ), 7 g of ammonium nitrate and 150 ml_ of distilled water were added. A 30 wt% ammonia solution was added dropwise till the pH of the solution was 9. The suspension was then heated up to 50 °C and left stirring for 8 h. At this point, the solvent was removed via vacuum evaporation, and the obtained solid was dried in oven at 70 °C overnight. The dried material was thus pyrolyzed in argon flow at 900 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

0.9 g of the composite material obtained as reported above are impregnated via incipient wetness with a aqueous solution containing 0.42 g of Cobalt (II) acetate in order to obtain a 10 wt %. final metal load. After impregnation the material is dried in oven at 70 °C and finally reduced in hydrogen flow at 500 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

EXAMPLE 4: Preparation of a "Catalyst D" In a 250 mL flask 5 g of alumina (Disperal 40, Sasol), 7 g of polymer (as described in WO2004/036674A2, Example 1 ), 7 g of ammonium nitrate and 150 mL of distilled water were added. A 30 wt% ammonia solution was added drop wise till the pH of the solution was 9. The suspension was then heated up to 50 °C and left stirring for 8 h. Then the solvent was removed via vacuum evaporation, and the obtained solid was dried in oven at 70 °C overnight. The dried material was thus pyrolyzed in argon flow at 900 °C for 2 h (heating rate from room temperature: 10 °C min^"1). 0.8 g of the composite material obtained as reported above are impregnated via incipient wetness with a aqueous solution containing 1.44 g of Iron (III) nitrate in order to obtain a 20 wt %. final metal load. After impregnation the material is dried in oven at 70 °C and finally reduced in hydrogen flow at 800 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

EXAMPLE 5: Preparation of a "Catalyst E"

In a 250 ml_ flask 5 g of alumina (Disperal 40, Sasol), 7 g of polymer (as described in WO2004/036674A2, Example 1 ), 7 g of ammonium nitrate and 150 ml_ of distilled water were added. A 30 wt% ammonia solution was added drop wise till the pH of the solution was 9. The suspension was then heated up to 50 °C and left stirring for 8 h. At this point, the solvent was removed via vacuum evaporation, and the obtained solid was dried in oven at 70 °C overnight. The dried material was thus pyrolyzed in argon flow at 900 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

0.8 g of the composite material obtained as reported above are impregnated via incipient wetness with a aqueous solution containing 0.99 g of cobalt (II) nitrate in order to obtain a 20 wt %. final metal load. After impregnation the material is dried in oven at 70 °C and finally reduced in hydrogen flow at 800 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

EXAMPLE 6: Preparation of a "Catalyst F"

In a 250 mL flask 5 g of alumina (Disperal 40, Sasol), 7 g of polymer (as described in WO2004/036674A2, Example 1 ), 7 g of ammonium nitrate and 150 mL of distilled water were added. A 30 wt% ammonia solution was added drop wise till the pH of the solution was 9. The suspension was then heated up to 50 °C and left stirring for 8 h. At this point, the solvent was removed via vacuum evaporation, and the obtained solid was dried in oven at 70 °C overnight. The dried material was thus pyrolyzed in argon flow at 900 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

0.8 g of the composite material obtained as reported above are impregnated via incipient wetness with a aqueous solution containing 0.92 g of cobalt (II) nitrate. After impregnation the material is dried in oven at 70 °C and finally reduced in hydrogen flow at 800 °C for 2 h (heating rate from room temperature: 10 °C min^"1). The composite material obtained after reduction step was impregnated via incipient wetness with a aqueous solution containing 0.31 g of nickel (II) nitrate in order to obtain a molar ratio Co:Ni=3:1. After second impregnation the material is dried in oven at 70 °C and finally re-reduced in hydrogen flow at 800 °C for 2 h (heating rate from room temperature: 10 °C min^"1).

EXAMPLE 7: Activity evaluation on ammonia decomposition 75 mg of Catalysts A, D and F prepared respectively as reported in Examples 1 , 4 and 6 have been placed in a quartz reactor (4 mm inner diameter) and then placed inside a tubular furnace. The furnace temperature was heated up to 600 °C (heating rate 10 °C min^"1) under argon flow and then in hydrogen for 30 minutes. At the end of this pretreatment, pure ammonia (18.8 ml_/min) was fluxed and the catalytic activity was measured keeping the catalyst at the temperature of 600 °C, 550 °C, 500 °C, 450 °C and 400 °C for 30 minutes each. As comparison we applied the same evaluation protocol to a commercial catalyst G90-B (Sϋd Chemie), that similarly does not contain noble metal. The measured conversions are reported in Figure 1. It is visible that the activity of Catalyst A starts at 400 °C and reaches 100% conversion at 650 °C, activity of Catalyst D starts at 400 °C and reaches 100% conversion at 600°C and catalyst F reaches almost 100% conversion at 550 °C while catalyst G90-B starts at 450 °C and reaches 100% conversion at 700 °C.

EXAMPLE 8: Surface area measurements

Surface areas of the supports and catalysts have been evaluated via a QUADRASORB SI (Quantachrome Instruments). The BET surface area has been determined in accordance with the "multipoint BET" methodology using points having p/p₀ in the 0.05 - 0.35 range. Microporosity has been measured with the t- plot technique implemented in the Quadrawin software. Table 1 : Surface area and microporosity of catalyst A, its precursor and alumina.

BET surface area Micropore area

Sample description

Alumina 56 0

Composite (Alumina + organic matter) 208 126

Catalyst A 197 144

It can be seen that after the deposition process and the following thermal treatment, the surface area increases considerably and this value is stable even after the deposition of the metallic particles and further thermal treatment at 500 °C (Table 1 ).

EXAMPLE 9: Influence of polymer/alumina ratio on the activity of resultant catalysts It has been found that the amount of polymer used for the composite support preparation, and thus the polymer/alumina ratio, has a great influence on the composite surface area and porosity.

In order to evaluate the influence of the ratio between organic polymer and inorganic support on surface properties and catalytic activity of the materials, catalysts with variable ratios polymer/alumina were prepared. For all these samples the synthetic procedure was similar to that described in Example 1. The only difference consisted in the last thermal treatment, run at 800 °C instead of 500 °C. The method for the surface properties investigation was the same as for example 8 and the catalytic activity measurements followed the protocol described in Example 7. The data obtained are reported in (Table 2). Table 2. Influence of polymer loading on the support porosity and catalyst activity for ammonia decomposition measured according to protocol listed in example 7.

BET surface area of the Catalyst activity as

Polymer/AI2O3 Ratio support ammonia conversion

0 56 19.9

0.5 176 21.3

0.75 207 29.5

1.0 238 42.3

1.2 273 47.1

1.4 208 38.2

^* measured at 500 °C, GHSV 15000 cm "Wg_∞t -h^"1.

The data reported in Table 2 show that the ratio polymer/inorganic support influences the surface area of the support itself and the catalysts activity, that follows the same trend registered for the BET surface area. Such trend has a bell- shape behavior and, in particular, it has been found a maximum of BET surface area and of catalyst activity for a Polymer/AI₂0₃ ratio equal to 1.2 (Fig 2),

EXAMPLE 10: Catalysts stability under ammonia stream at high temperature Aging tests have been performed in the same apparatus described in example 7 using technical grade ammonia (99.75 vol.% NH₃, 0.25 vol.% H₂O) at P=O.1 MPa and GHSV=I 5000 cm³ g_cat ^"1 h^"1. In particular, 75 mg of the catalyst was first tested following the protocol described in example 7. Successively, the temperature was raised (10 °C min^"1) to 700 °C and the catalyst was kept at this temperature for 100 h. Then, temperature was further raised (10 °C min^"1) to 800°C and the catalyst was kept at this temperature for 3 h. Finally temperature was decreased to 600 °C, and the catalyst tested again following the protocol described in example 7. Non limiting examples of catalyst stability (for the catalysts prepared according to example D and E) under the above mentioned conditions are reported in Table 3. Table 3: Catalysts activity before and after aging.

Catalyst D Catalyst E

Temperature

Conversion (%) Conversion (%) Conversion (%) Conversion (%) (O) before aging after aging before aging after aging

600 100.0 100.0 100.0 100.0

550 75.0 111 87.0 81 .9

500 51 .7 51 .5 51 .7 55.4

450 22.9 23.4 23.4 24.7

400 5.6 6.6 8.2 9.1

The data regarding the catalytic activity before and after aging tests confirm the stability of the prepared catalysts even after prolonged treatments at high temperatures.

EXAMPLE 1 1 : Metal particle size determination.

Non-noble metals size and particles dispersion were determinated by

Transmission Electron Microscopy (TEM) technique using a JEOL 200 EX microscope (12OkV) and magnifications from 140.00Ox to 280.00Ox. The specimens for TEM were prepared by dispersion of the catalyst sample in ethanol, dropping it on a copper microscope grid covered with carbon followed by solvent evaporation.

For instance, "Catalyst A" shows a bimodal size distribution, most of nanoparticles being characterized by a average diameter of 3 nm, but also few bigger iron clusters were observed (Table 4).

Table 4: Iron size distribution and particles frequency in case of "catalyst A". Iron particles diameter Particles frequency (%) d=1.9 - 4.3 nm (d_aVerag_e=3 nm) 98 d=21 - 28 nm (d_avθragθ=25 nm) 2

Claims

1. Nanoparticle catalysts based on non-noble metals or their oxides or mixtures thereof supported on inorganic porous material obtained by means of a process comprising the following steps: i. preparation of the support by means of coating an inorganic porous material with an organic material and subsequent pyrolysis; ii. deposition on the support of ions of said non-noble metals by means impregnation and subsequent heat treatment reducing or oxidant depending on the desired active metallic phase in form of metal at oxidation grade zero, or in form of oxide, or mixtures thereof; wherein said non-noble metals o their oxides are chosen among those of the first transition series; said inorganic porous material is chosen among metallic oxides alumina, ZrO₂, CeO_x, MgO, MgAI₂O₄, La₂O₃, SiO₂, Y₂O₃Or their mixture; said organic material contains carbon, nitrogen and oxygen, comprises at least two aromatic or heteroaromatic groups and at least one conjugated double bond.

2. Catalysts according to claim 1 wherein said non-noble metals, or their oxides or mixtures there of are chosen among Fe, Co, Ni or their mixtures.

3. Catalysts according to claim 1 wherein said organic material is a compound with formula (A)

where R1 is chosen from the group consisting of: H and a hydrocarbon radical having from 1 to 10 carbon atoms, possible halogenated, R2 and R3 independently represent preferentially a electron-attractor group consisting of hydrogen, halogen, acyl, ester, carboxylic acid, formyl, nitrile, sulfonic acid, aryl groups, linear or branched alkyl groups having 1 to 15 carbon atoms possible functionalized with halogens or linked together to form one or more condensed cycles with phenyl ring and nitro groups; or is a polymer represented by the formula (C)

(C) where, y can vary between 2 and 120; x can be 1 or 2, n can vary between 1 and 3, and R1 , R2, R3 are defined as above, and R4 and R5 independently represent a electron-donor group chosen from a group containing H, OH, ether, amines, aryl and alkyl, linear or branched groups, having from 1 to 15 carbon atoms.

Catalysts according to claim 1 further comprising at least a promoter, belonging to the alkaline, earth-alkaline and lanthanides gruops of the periodic table.

Catalysts according to claimi wherein the ratio between organic material and inorganic porous material is comprised between 0.5 and 2 wt/wt.

Catalysts according to any of claims 1 -5 wherein the total metal loading is comprised between 5 and 50 % by weight respect to the total weight.

Catalysts according to claim 2 characterized by a surface area comprised between 30 and 350 m²g^"1.

8. Process for the preparation of catalysts according to any of claims 1 -7 comprising the following steps: a) formation of a mixture comprising the inorganic porous material and the organic material in a solvent able to dissolve the organic material at a temperature comprised between 20 and 90 °C; b) removal of the solvent and drying; c) heat treatment in inert atmosphere at a temperature comprised between

400 and 1000°C; d) deposition of metal ions of non-noble metals by means of classical impregnation methods at temperature comprised between 20 and 90 °C; e) drying; f) heat treatment at a temperature comprised between 400 and 1000 °C in presence of hydrogen for obtaining of the active metal phase in form of metal at zero oxidation grade; in presence of oxygen for obtaining of the active metal phase in form of metal oxide. 9. Process according to claim 8 wherein said d) deposition of metal ions of non- noble metals is performed by means of incipient wetness impregnation method.

10. Process according to any of claims 8-9 wherein steps (d)-(f) are repeated consecutively once or more times when the active metals are more than one. 1 1. Process according to any of claims 8-10 for the preparation of catalyst according to claim 4 wherein, at any step of the process, at least a promoter, belonging to the alkaline, earth-alkaline and lanthanides gruops of the periodic table, is added.

12. A method for producing hydrogen from ammonia, said method wherein a catalyst according to any of claims 1 -7 is used.

13. Ammonia reformers comprising at least a catalyst according to any of claims 1 -7.

14. Hydrogen powered systems, such as internal combustion engine fueled by hydrogen/ammonia mixtures as well as fuel cells, said systems comprising at least an ammonia reformer according to claim 13, or wherein the necessary hydrogen is produced by the method according to claim 12.