Process for production of hydrogen

Abstract

The present invention relates to a process for production of hydrogen at low temperature starting from alcohols without formation of carbon using an oxyhydride material based on cerium and nickel and to the use of such a material as catalyst for transformation of alcohols to hydrogen.

Claims

1. Process for production of hydrogen at low temperature by transformation of an alcohol or of a mixture of alcohols, said process comprising the steps of: 1) a first step of synthesis of an electrically neutral oxyhydride material M1, based on cerium, nickel, oxygen atoms, hydrogen atoms and optionally a metal M selected from Al and Zr, and in said material: i) the Ni/Ce molar ratio varies from 0.1 to 5, ii) the M/Ce molar ratio varies from 0 to 1, and iii) at least a proportion of the hydrogen atoms present in said material M1 is in the form of hydride ions, said synthesis being carried out according to the following substeps 1-i) to 1-v): 1-i) a first substep of preparation of an aqueous solution comprising at least one cerium precursor, at least one nickel precursor and optionally at least one precursor of metal M, 1-ii) a second substep of coprecipitation of said precursors of cerium, of nickel and optionally of metal M in the form of the corresponding hydroxides of cerium, of nickel and optionally of metal M, by adding at least one precipitant to said aqueous solution, 1-iii) a third substep of filtration of said hydroxides to obtain a filtered solid, 1-iv) a fourth substep of drying the filtered solid obtained above in substep 1-iii) at a temperature between 40 C. and 150 C., for a time between 1 and 24 hours, to obtain an electrically neutral solid material M2 based on cerium, nickel, oxygen atoms, hydrogen atoms and optionally a metal M, in which: i) the definitions of metal M and the Ni/Ce and M/Ce molar ratios are the same as those relating to the oxyhydride material M1, ii) at least a proportion of the hydrogen atoms present in said material M2 forms hydroxyl functions with the oxygen atoms, and iii) said solid material M2 is free from hydride ions, and 1-v) a fifth substep of treatment of the solid material M2 obtained above in the preceding step in the presence of hydrogen, to obtain an oxyhydride material M1, 2) a second step of contacting, at low temperature, the oxyhydride material M1 obtained above in the preceding step, firstly with a gas mixture comprising at least one lower alcohol, water and nitrogen, then secondly with oxygen, wherein the step of synthesis of the oxyhydride material M1 does not comprise a substep of calcination.

2. Process according to claim 1, wherein the cerium precursor is a cerium(III) salt selected from cerium nitrate, cerium acetate and cerium chloride and in that the nickel precursor is a nickel(II) salt selected from nickel nitrate, nickel chloride and nickel sulphate.

3. Process according to claim 1, wherein the concentration of cerium precursor and of nickel precursor in said aqueous solution varies independently from 0.1 to 1 mol/l.

4. Process according to claim 1, wherein the precipitant is selected from triethylamine, ammonium hydroxide, potassium hydroxide, sodium hydroxide and sodium carbonate.

5. Process according to claim 1, wherein the low temperature is a temperature in the range from 20 C. to 60 C.

6. Process according to claim 1, wherein the substep 1-v) of treatment of the solid material M2 in the presence of hydrogen is carried out at a temperature from 50 C. to 400 C.

7. Process according to claim 1, wherein the oxyhydride material M1 is selected from those in which the M/Ce molar ratio is equal to zero and the Ni/Ce molar ratio varies from 0.3 to 1.

8. Process according to claim 1, wherein said alcohol is selected from methanol, ethanol, propan-1-ol, butan-1-ol and pentan-1-ol and bio-ethanol.

9. Process according to claim 1, wherein said contacting step 2) is carried out according to the following sequences: 2-i) introducing a water/alcohol/nitrogen gas mixture into a reactor comprising oxyhydride material M1 obtained in the preceding step 1), at a temperature of at least 130 C., 2-ii) introducing oxygen into the reactor and maintaining the temperature for an induction period of at least 3 minutes, then 2-iii) lowering the temperature to a temperature below 60 C.

10. Process according to claim 9, wherein said water/alcohol/nitrogen gas mixture is fed into the reactor at a temperature of 160 C. during sequence 2-i) and in that the temperature is lowered to a temperature of 50 C. during step 2-iii).

11. Process according to claim 9 wherein said water/alcohol/nitrogen gas mixture fed into the reactor at the start contains 15 mol % of alcohol relative to the water/alcohol/nitrogen gas mixture.

12. Process according to claim 1, wherein the water/alcohol molar ratio in the gas mixture varies from 1/2 to 13/1.

13. Process according to claim 1, wherein the flow rate of the water/alcohol/nitrogen/oxygen gas mixture varies from 10 to 100 ml/min.

14. Process according to claim 1, wherein the Oz/alcohol molar ratio varies from 0.5/1 to 2.5/1.

15. Process according to claim 1, wherein an alcohol/water/O.sub.2/N.sub.2 gas mixture is used in which the molar proportions of the alcohol/water/O.sub.2/N.sub.2 mixture are 1/3/1.6/1.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1(I)-1(III) show variations in hydrogen consumption (H.sub.2 cons., in arbitrary units a.u.) as a function of the temperature (in C.) for example 1, in accordance with one embodiment;

(2) FIGS. 2(I)-2(II) show variation in intensity (in arbitrary units a.u.) as a function of the angle 2 (in degrees) for example 1, in accordance with one embodiment;

(3) FIGS. 3(I)-3(II) show variation in intensity (in arbitrary units a.u.) as a function of the energy (in cm.sup.1) for example 1, in accordance with one embodiment:

(4) FIG. 4 shows that the reaction developed in a stable manner and that the hydrogen compound is obtained in a high proportion for example 2, in accordance with one embodiment;

(5) FIGS. 5(I)-5(II) and 6(I)-6(I) show variation in intensity (in arbitrary units a.u.) as a function of energy (in cm.sup.1) for example 2, in accordance with one embodiment;

(6) FIG. 7 shows an ethanol conversion rate in example 3, in accordance with one embodiment; and

(7) FIG. 8 shows an ethanol conversion rate in example 4, in accordance with one embodiment.

DETAILED DESCRIPTION

(8) The present invention is illustrated by the following embodiment examples, but it is not limited to these.

Example 1

Preparation and Characterizations of Solid Materials M2 According to the Invention Comparisons with Calcined Compounds According to the Prior Art

(9) 1.1 Preparation of the Solid Materials M2 Resulting from the Drying, Step 1-iv) of the Process According to the Invention (Dried Compounds)

(10) 1.1-a) Preparation of the Dried Compound 1, in which the Ni/Ce Molar Ratio is Equal to 1 and the M/Ce Molar Ratio is Equal to 0

(11) The dried compound 1 was prepared by coprecipitation of the corresponding hydroxides starting from a solution comprising a volume of 100 mL of 0.5 M aqueous solution of cerium nitrate and a volume of 100 mL of 0.5 M aqueous solution of nickel nitrate and using triethylamine as the precipitant.

(12) Said solution was added dropwise, quickly, to a volume of 250 mL of a solution of triethylamine diluted to 1.5 Ni in methanol.

(13) During this addition, formation of a precipitate of metal hydroxides was observed, which was filtered, washed and rinsed with a total volume equivalent to the volume recovered, 3 times, with water and with methanol. The solid obtained was then dried at 100 C. for 24 hours and ground.

(14) 1.1-b) Preparation of the Dried Compound 2, in which the Ni/Ce Molar Ratio is Equal to 0.5 and the M/Ce Molar Ratio is Equal to 0

(15) The dried compound 2 was prepared by coprecipitation of the corresponding hydroxides starting from a solution comprising a volume of 200 mL of 0.5 M aqueous solution of cerium nitrate and a volume of 100 mL of 0.5 M aqueous solution of nickel nitrate and using triethylamine as the precipitant.

(16) Said solution was added dropwise, quickly, to a volume of 375 mL of a solution of triethylamine diluted to 1.5 M in methanol.

(17) During this addition, formation of a precipitate of metal hydroxides was observed, which was filtered, washed and rinsed with a total volume equivalent to the volume recovered, 3 times, with water and with methanol. The solid obtained was then dried at 100 C. for 24 hours and ground.

(18) 1.1-c) Preparation of the Dried Compound 3, in which the Ni/Ce Molar Ratio is Equal to 0.25 and the M/Ce Molar Ratio is Equal to 0

(19) The dried compound 3 was prepared by coprecipitation of the corresponding hydroxides starting from a solution comprising a volume of 200 mL of 0.5 M aqueous solution of cerium nitrate and a volume of 50 mL of 0.5 M aqueous solution of nickel nitrate and using triethylamine as the precipitant.

(20) Said solution was added dropwise, quickly, to a volume of 312.5 mL of a solution of triethylamine diluted to 1.5 NI in methanol.

(21) During this addition, formation of a precipitate of metal hydroxides was observed, which was filtered, washed and rinsed with a total volume equivalent to the volume recovered, 3 times, with water and with methanol. The solid obtained was then dried at 100 C. for 24 hours and ground.

(22) 1.2 Characterization of the Dried Compounds 1, 2 and 3 and Comparison with Calcined Compounds According to the Prior Art

(23) The dried compounds 1, 2 and 3 were analysed by measurements of programmed temperature reduction (PTR).

(24) These measurements were carried out with an analyser comprising a thermal conductivity detector (TCD), sold under the trade name Micromeritics AutoChem 2920 Analyzer by the company Micromeritics.

(25) The appended FIG. 1 shows the variation in hydrogen consumption (H.sub.2 cons., in arbitrary units a.u.) as a function of the temperature (in C.) on the one hand for the dried compounds 1, 2 and 3 resulting from step 1-iv) of the process according to the invention (solid materials M2) and on the other hand for certain calcined compounds corresponding to the formula CeNi.sub.xO.sub.y already described in Pirez et al. (ibid.) and in Jalowiecki-Duhamel et al., Int. J. Hydrogen Energy, 2010, 35, 12741-12750.

(26) In FIG. 1, the first peak corresponds to the temperature required for carrying out the step of treatment in the presence of hydrogen, leading to an oxyhydride. It has been shown, moreover, that a higher temperature of treatment in the presence of hydrogen leads to a decrease in the rate of ethanol conversion during the next step of bringing the ethanol into contact with the oxyhydride previously formed.

(27) According to FIG. 1, the dried compounds 3 (FIG. 1-Ia), 2 (FIG. 1-Ib) and 1 (FIG. 1-Ic) must be treated in the presence of hydrogen at a temperature between 200 C. and 300 C. and more particularly at a temperature of about 250 C.-270 C. In fact, a peak of reduction at low temperature is observed at 250-270 C.

(28) For comparative purposes, the compounds calcined at 500 C. CeNi.sub.0.2O.sub.y (FIG. 1-IIa), CeNi.sub.0.4O.sub.y (FIG. 1-IIb), CeNi.sub.0.7O.sub.y (FIG. 1-IIc), CeNi.sub.0.9O.sub.y (FIG. 1-IId) and CeNi.sub.1.0O.sub.y (FIG. 1-III) must also be treated in the presence of hydrogen at a temperature between 200 C. and 300 C.

(29) In conclusion, FIG. 1 shows that the dried compounds 1, 2 and 3 (solid materials M2) display behaviour that is different from the calcined compounds at so equivalent nickel content with a far greater peak of reduction at low temperature on the dried compounds 1, 2 and 3 (solid materials M2).

(30) Moreover, analyses by X-ray diffractometry (XRD) of the dried compounds 1, 2 and 3 (solid materials M2 obtained according to step 1-iv) of the process according to the invention) and, for comparative purposes, of certain calcined compounds described in the work of Ponchel et al. (Phys. Chem. Chem. Phys., 2000, 2, 303-312), were carried out.

(31) The XRD analyses were carried out using a diffractometer sold under the trade name D8 Advance by the company Bruker.

(32) These analyses make it possible to show whether the compounds have a ceria phase CeO.sub.2 and/or a nickel phase. The nickel phase in the calcined compounds of the prior art corresponds to nickel oxide NiO. The nickel phase in the dried compounds 1, 2 and 3 (solid materials M2) obtained according to the process of the invention, when observed by XRD, corresponds to a complex mixture of nickel hydroxides. For low Ni contents, no phase associated with Ni is observed, therefore it may be amorphous and/or the nickel ions may be inserted in the ceria phase, forming a solid solution.

(33) FIG. 2 shows the variation in intensity (in arbitrary units a.u.) as a function of the angle 2 (in degrees). In FIG. 2-I, the crosses correspond to the ceria phase CeO.sub.2. In FIG. 2-II the filled circles correspond to the ceria phase CeO.sub.2 and the empty squares correspond to the nickel phase.

(34) FIG. 2-I shows absence of a nickel phase in the dried compounds 3 (FIG. 2-Ia), 2 (FIG. 2-Ib) and 1 (FIG. 2-Ic), obtained by the process according to the invention.

(35) For comparative purposes, FIG. 2-II shows that the nickel phase is not observed in the compound CeO, and in the compound calcined at 500 C. CeNi.sub.0.2O.sub.y, which has a very low nickel content. In contrast, it is observed in the compounds calcined at 500 C. CeNi.sub.0.5O.sub.y, CeNi.sub.0.7O.sub.y, and CeNi.sub.1.0O.sub.y.

(36) Regarding the ceria phase, it is observed in the dried compounds 1, 2 and 3 according to the invention, as well as in all the calcined compounds of the prior art. In contrast, the presence of a background noise in the XRD spectra corresponding to the dried compounds according to the invention (FIG. 2-I) indicates that the ceria phase is crystallized less well in these compounds than in the calcined compounds of the prior art (FIG. 2-II.

(37) Finally, measurements of specific surface area of the dried compounds 1, 2 and 3 (solid materials M2) obtained according to the process of the invention were carried out.

(38) These measurements of specific surface areas were performed using the BET method (Brunauen-Emmett-Teller) and were carried out with equipment sold under the trade name Tristar II 3020 by the company Micromeritics.

(39) Table 1 below shows the specific surface areas (in m.sup.2.Math.g.sup.1) the dried compounds 1, 2 and 3 and, for comparison, of various calcined compounds of formula CeNi.sub.xO.sub.y (x in the range from 0.07 to 1), of NiO and of CeO.sub.2 reported in Pirez et al. (ibid.) and Jalowiecki-Duhamel et al. (ibid.).

(40) TABLE-US-00001 TABLE 1 Specific surface area Crystallite size.sup.(a) Dried (B.E.T) nm compounds m.sup.2 .Math. g.sup.1 CeO.sub.2 Nickel hydroxides 1 145 3.3 2 141 4.2 3 75 4.6 Calcined Specific surface area Crystallite size.sup.(a) compounds of (B.E.T) nm the prior art m.sup.2 .Math. g.sup.1 CeO.sub.2 NiO CeNi.sub.5.0Oy 84 4.6 9.4 CeNi.sub.1.0Oy 94 5.0 10.0 CeNi.sub.0.9Oy 109 4.4 11.0 CeNi.sub.0.7Oy 91 4.8 12.0 CeNi.sub.0.4Oy 136 4.7 8.0 CeNi.sub.0.2Oy 100 5.1 CeNi.sub.0.07Oy 92 5.6 CeO.sub.2 61 7.8 NiO 27 20.8 .sup.(a)deduced from XRD analysis using Scherrer's equation

(41) In conclusion, the specific surface areas are of the same order of magnitude throughout for the dried compounds 1, 2 and 3 according to the invention and the calcined compounds according to the prior art.

(42) In contrast, it appears that the specific surface area of the dried compound 1 is greater (145 m.sup.2.Math.g.sup.1) than the specific surface area of a calcined compound (CeNi.sub.1.0O.sub.y)(94 m.sup.2.Math.g.sup.1) with the same nickel content.

(43) Table 1 also shows the size (in nm) of the crystallites of the ceria phase and the size (in nm) of the crystallites of the nickel phase in the various compounds when it was possible to determine them.

(44) In fact, in the calcined compounds according to the prior art, when x0.3 (low nickel content), the size of the crystallites of the nickel phase cannot be Obtained. Moreover, the size of the crystallites of the nickel phase cannot be obtained for the dried compounds 1, 2 and 3. In fact, it was observed that in these dried compounds, the nickel phase appears when the Ni/Ce molar ratio is strictly greater than 1. These observations are in agreement with the XRD spectra described above.

(45) Moreover, the size of the crystallites of the ceria phase could be determined for all the dried and calcined compounds. According to Table 1, the average size of w the particles of CeO.sub.2 in the dried compounds is smaller compared to the average size of the particles of CeO.sub.2 in the calcined compounds.

(46) Neutron diffusion experiments (INS) were also carried out on the dried compound 1 using the spectrometer IN1 Lagrange of the Institut Lane Langevin de Grenoble, France (ILL), at 10 K using a Cu(220) monochromator for the energy transfers between 200 and 2500 cm.sup.1 and compared to those reported previously on the compound calcined at 500 C. CeNi.sub.1.0O.sub.y, and obtained using the IN1 spectrometer of the Institut Lane Langevin de Grenoble, France (ILL), at 10 K using a monochromator of Cu(220) for the energy transfers between 200 and 2500 cm.sup.1.

(47) Before performing the INS analyses, the solid that we wish to analyse is placed in a cell of the apparatus and undergoes a treatment in situ under vacuum at 200 C. for 2 hours. This treatment can thus ensure that the physisorbed water present in the ambient air has been removed completely.

(48) FIG. 3 shows the variation in intensity (in arbitrary units a.u.) as a function of the energy (in cm.sup.1).

(49) More particularly, FIG. 3 shows the neutron diffusion analysis of the dried compound 1 (FIG. 3-I) and, for comparison, the analysis of the calcined compound CeNi.sub.1.0O.sub.y already described in Jalowiecki-Duharnel et al., Int. J. Nuclear Hydrogen Production and Applications, 2009, 2, 2, 148-158 (FIG. 3-II.

(50) FIG. 3-I shows the presence of numerous hydroxyl functions in the dried compound 1 characterized by the peaks at 440 cm.sup.1 and 660 cm.sup.1. FIG. 3-II also shows the presence of hydroxyl functions in the compound calcined at 500 C. CeNi.sub.1.0O characterized by the peaks at 250 cm.sup.1, 400 cm.sup.1 and 630 cm.sup.1.

(51) Moreover, the chemical formulae of the dried compounds 1, 2 and 3 were evaluated on the basis of results of elemental analyses and are as follows: for compound 1: CeM.sub.pNi.sub.xO.sub.yH.sub.z (I-1) in which p=0, x=1, y=5.8 and z 3.8. for compound 2: CeM.sub.pNi.sub.xO.sub.yH.sub.z (I-2) in which p=0, x=0.4, y=4.0 and z=2.4, for compound 3: CeM.sub.pNi.sub.xO.sub.yH.sub.z (I-3) in which p=0, x=0.2, y=3.3 and z=2.1.

Example 2

Production of Hydrogen by the Process According to the Invention

(52) 2.1 Production of Hydrogen by the Process According to the Invention Catalysed by an Oxyhydride Material M1 in which the Ni/Ce Molar Ratio is Equal to 1 and the M/Ce Molar Ratio is Equal to 0 (Catalyst 1)

(53) 0.03 g of the dried compound 1 obtained above in example 1.1-a) (solid material M2) was put in a quartz reactor. This material was then treated in situ with hydrogen at 250 C. for 10 hours to form the corresponding oxyhydride material M1 (catalyst 1).

(54) A mixture of water and ethanol was prepared with a water/ethanol molar ratio of 3/1.

(55) The resultant mixture was heated and vaporized in a preheating chamber in a nitrogen stream in such a way that about 15 mol % of ethanol relative to the ethanol/water/nitrogen gas mixture was used.

(56) The reactor containing catalyst 1 was then supplied with a gaseous stream of ethanol/water/nitrogen mixture at 165 C. with a total gas flow rate of 60 ml/min. Then oxygen was fed into the reactor in such a way that the ethanol/water/oxygen/nitrogen gas mixture is 1/3/1.6/1.3 with a total gas flow rate of 60 ml/min. The furnace temperature was maintained for 2-3 minutes after introduction of the oxygen and was then lowered to 50 C.

(57) The measured reaction temperature was 320 C. inside the reactor, largely due to the reactivity between the hydride ions and oxygen.

(58) The reaction was stable for at least 50 hours.

(59) The gases were analysed in line at reactor outlet by gas chromatography (GC) using a chromatograph coupled to a flame ionization detector (HD) and to a thermal conductivity detector (TCD), sold under the trade name Trace GC Ultra by the company Thermo Electron Corporation.

(60) The data were collected as a function of time and are reported in the appended FIG. 4, in which the ethanol conversion rate (in mol %, filled black diamonds) and the distribution of the different gas species formed and analysed in line (in mol %) are expressed as a function of time (in h), the empty diamonds corresponding to H.sub.2, the empty circles to CO.sub.2, the filled black circles to CO, the empty triangles to CH.sub.4 and the empty squares to acetaldehyde CH.sub.3CHO.

(61) Complete conversion of the ethanol and oxygen was obtained.

(62) The appended FIG. 4 shows that the reaction developed in a stable manner and that the hydrogen compound is obtained in a high proportion.

(63) The products formed are gaseous and comprise 42 mol % of H.sub.2, 38 mol % of CO.sub.2 and 18 mol % of CO.

(64) Very small amounts of methane and acetaldehyde are present (CH.sub.4+CH.sub.3CHO1.6%).

(65) Extremely slight formation of carbon was observed after 50 hours of reaction (4 mg/gh) compared to a value of 63 mg/gh reported in the work of Pirez et al. (ibid.) using an oxyhydride that had undergone a calcination step.

(66) 2.2 Characterization of the Oxyhydride Material M1 in which the Ni/Ce Molar Ratio is Equal to 1 and the M/Ce Molar Ratio is Equal to 0 (Catalyst 1)

(67) Neutron diffusion experiments (INS) were carried out on catalyst 1 obtained according to the process of the invention and, for comparison, on the oxyhydride catalyst obtained by the process described in Pirez et al. (ibid.) using the same apparatus as that described above in example 1.2.

(68) FIGS. 5 and 6 show the variation in intensity (in arbitrary units a.u.) as a function of energy (in cm.sup.1),

(69) FIG. 5-I shows the neutron diffusion analysis of catalyst 1, obtained after treatment of the dried compound 1 in the presence of hydrogen for 10 hours at 250 C. according to step 1-v) of the process according to the invention (curve drawn with solid line). Three broad peaks are observed at about 470 cm.sup.1, 640 cm.sup.1 and 900 cm.sup.1. The peak at 470 cm.sup.1 can be attributed to the hydride ions. When the catalyst 1 obtained is treated in the presence of oxygen (curve drawn with dotted line), the peaks at 470 cm.sup.1 and at 900 cm.sup.1 decrease, the reaction being very exothermic, and several broad peaks are observed, including peaks at 440 cm.sup.1 and at 660 cm.sup.1 indicating formation of hydroxyl functions during oxidation.

(70) For comparative purposes, FIG. 5-II shows the neutron diffusion analysis of the oxyhydride obtained after treatment of the calcined compound of the prior art CeNi.sub.1.0O.sub.y in the presence of hydrogen for 10 hours at 250 C. according to Jalowiecki-Duhamel et al., Int. J. Nuclear Hydrogen Production and Applications, 2009, 2, 2, 148-158 (curve drawn with solid line). When the oxyhydride obtained is treated in the presence of oxygen, the INS spectrum is represented by the curve drawn with a dotted line.

(71) In conclusion, the neutron diffusion analyses of catalyst 1 obtained according to the process of the invention (FIG. 5-I) and the oxyhydride obtained according to the process of the prior art comprising a calcination step (FIG. 5-II are different.

(72) FIG. 6-I shows the difference between the two INS spectra in FIG. 5-I curve drawn with solid line in FIG. 5-I minus curve drawn with dotted line in FIG. 5-I) FIG. 6-II shows the difference between the two INS spectra in FIG. 5-II (curve drawn with solid line in FIG. 5-II minus curve drawn with dotted line in FIG. 5-II.

(73) FIG. 6 thus provides good visualization of the hydride ions inserted during the treatment in the presence of hydrogen and which then reacted and disappeared during the treatment in the presence of oxygen. These hydride ions are thus characterized by a fairly thin peak at 490 cm.sup.1.

Example 3

Production of Hydrogen by the Process According to the Invention

(74) In this example, production of hydrogen was carried out, catalysed by an oxyhydride material M1 in which the Ni/Ce ratio is equal to 0.5 and the M/Ce ratio is equal to 0 (catalyst 2).

(75) 0.03 g of the dried compound 2 as obtained above in example 1.1-b) was put in a quartz reactor. This material was then treated in situ with hydrogen at 250 C. for 10 hours to form the corresponding oxyhydride material M1 (catalyst 2).

(76) A mixture of water and ethanol was prepared with a water/ethanol molar ratio of 3/1.

(77) The resultant mixture was heated and vaporized in a preheating chamber in a nitrogen stream in such a way that about 15 mol % of ethanol relative to the ethanol/water/nitrogen gas mixture was used.

(78) The reactor containing the catalyst 2 was then supplied with a gaseous stream of ethanol/water/nitrogen mixture at 160 C. with a total gas flow rate of 60 ml/min. Then oxygen was fed into the reactor in such a way that the ethanol/water/oxygen/nitrogen gas mixture is 1/3/1.6/1.3 with a total gas flow rate of 60 ml/min. The furnace temperature was maintained for 2-3 minutes after introduction of the oxygen and was then lowered to 50 C.

(79) The measured reaction temperature was 335 C. inside the reactor, largely due to the reactivity between the hydride ions and oxygen.

(80) The reaction was stable for at least 75 hours.

(81) The gases are analysed in line at reactor outlet by gas chromatography as indicated above in example 2.

(82) The data were collected as a function of time and are reported in the appended FIG. 7, in which the ethanol conversion rate (in mol %, filled black diamonds) and the distribution of the different gas species formed and analysed in line (in mol %) are expressed as a function of time (in h), the empty diamonds corresponding to H.sub.2, the empty circles to CO.sub.2, the filled black circles to CO, the empty triangles to CH.sub.4 and the empty squares to acetaldehyde CH.sub.3CHO.

(83) Complete conversion of the ethanol and oxygen was obtained.

(84) The appended FIG. 7 shows that the reaction developed in a stable manner and that the hydrogen compound is obtained in a high proportion.

(85) The products formed are gaseous and comprise 37 mol % of H.sub.2, 41 mol % of CO.sub.2 and 20 mol % of CO.

(86) Very small amounts of methane and acetaldehyde are present (CH.sub.4+CH.sub.3CHO1.7%).

(87) Extremely slight formation of carbon was observed after 75 hours of reaction (1.2 mg/gh) compared to a value of 63 mg/gh reported in the work of Pirez et al. (ibid.) using an oxyhydride that had undergone a calcination step.

Example 4

Production of Hydrogen by the Process According to the Invention

(88) In this example, production of hydrogen was carried out, catalysed by an oxyhydride material M1 in which the Ni/Ce ratio is equal to 0.25 and the MICe ratio is equal to 0 (catalyst 3).

(89) 0.03 g of the dried compound 3 as obtained above in example 1.1-c) was put in a quartz reactor. This material was then treated in situ with hydrogen at 250 C. for 10 hours to form the corresponding oxyhydride material M1 (catalyst 3).

(90) A mixture of water and ethanol was prepared with a water/ethanol molar ratio of 3/1.

(91) The resultant mixture was heated and vaporized in a preheating chamber in a nitrogen stream in such a way that about 15 mol % of ethanol, relative to the ethanol/water/nitrogen gas mixture, was used,

(92) The reactor containing the catalyst 3 was then supplied with a gaseous stream of ethanol/water/nitrogen mixture at 256 C. with a total gas flow rate of 60 ml/min. Then oxygen was fed into the reactor in such a way that the ethanol/water/oxygen/nitrogen gas mixture is 1/3/1.6/1.3 with a total gas flow rate of 60 ml/min. The furnace temperature was maintained for 2-3 minutes after introduction of the oxygen and was then lowered to 50 C.

(93) The measured reaction temperature was 335 C. inside the reactor, largely due to the reactivity between the hydride ions and oxygen.

(94) The reaction was stable for at least 20 hours.

(95) The gases are analysed in line at reactor outlet by gas chromatography as indicated above in example 2.

(96) The data were collected as a function of time and are reported in the appended FIG. 8, in which the ethanol conversion rate (in mol %, filled black diamonds) and the distribution of the different gas species formed and analysed in line (in mol %) are expressed as a function of time (in h), the empty diamonds corresponding to H.sub.2, the empty circles to CO.sub.2, the filled black circles to CO, the empty triangles to CH.sub.4 and the empty squares to acetaldehyde CH.sub.3CHO.

(97) Complete conversion of the ethanol and oxygen was obtained.

(98) The appended FIG. 8 shows that the reaction developed in a stable manner and that the hydrogen compound is obtained in a high proportion.

(99) The products formed are gaseous and comprise 34 mol % of H.sub.2, 47 mol % of CO.sub.2 and 18 mol % of CO.

(100) Very small amounts of methane and acetaldehyde are present (CH.sub.4+CH.sub.3CHO1.8%).

(101) No formation of carbon was observed after 20 hours of reaction, compared to a value of 63 mglgh reported in the work of Pirez et al. (ibid.) using an oxyhydride that had undergone a calcination step.