WO2002032573A1 - The preparation of a hydrazine decomposition catalyst and its use - Google Patents

Abstract

The present invention provides a hydrazine decomposition catalyst which can decompose pure or hydrated hydrazine at room temperature into N2 and H2, and its preparation. The catalyst has following composition: XYC, wherein, X is metal element of Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, In, Os, Ir, Pt, Au, Y is perofskite or fluorite or millerite-type complex oxide, C is nanometer carbon black, X can be one or more metal elements, Y is one of the three type oxides, and C can be included or not be included. The catalyst of the present invention can decompose pure or hydrated hydrazine to produce H2 with high selectivity, which can provide a H2 source for fuel cells or as a H2 source used in metal processing.

Description

 Preparation and application of hydrazine decomposition catalyst

FIELD OF THE INVENTION The present invention relates to the preparation and application of a catalyst, in particular to a catalyst capable of decomposing hydrazine into N ₂ and ¾ at normal temperature. BACKGROUND Hydrazine is a widely used chemical material containing hydrogen. There are several main ways of hydrazine decomposition: 3N ₂ ¾ → N ₂ + 4 Li ₃ ; ΔΗ =-1 STkJ.mor ¹

H2 + N ₂ ¾ → 2 dish ₃ ; ΔΗ =-187.8kJ.mor '

It is not difficult to see from the above thermodynamic data that hydrazine is easily decomposed, and the products are mainly NH ₃ and N ₂ . In the past 60 years, researchers have done a lot of research on the decomposition of hydrazine on the surface of metal single crystals, metals and metal-supported catalysts, and believe that there are two ways to break the intramolecular bond of hydrazine: one is the break of NH bond; two It is the break of the NN key. The NH bond energy is δΑΚπιοΓ ¹ and the NN bond energy is θθυ.ιηοΓ ¹ , so the NN bond is more easily broken in thermodynamics. Studies on the adsorption and dissociation of hydrazine on the surface of metal single crystals (ML Wagner ed al., Surface Science 257

(1991) 113-128; R. Dopheide etal., 257 (1991) 86-96; Diann J. Alberas et al., Surface Science 278 (1992) 51-61): Hydrazine on the surface of different metal single crystals Fe (lll ), Ru (001), Rh (lll), Pd (100), Os (100), Ir (lll) ₅ Pt (lll) have selective NH and NN bond cleavage. NN bonds are easily broken on the Fe (ll11) crystal plane. On the R (111) crystal plane, the NH bond is easily activated and broken. Ken-IchiAika et al. (Joural of Catalysis 19, 140-143

(1970) The hydrazine decomposition performance of Ir, Ru, Pt, Ni, Co, Rh, Fe, W, Mo metals or catalysts prepared on celite or diatomaceous earth was studied, and hydrazine was found to be below 200 ^{The Q} C decomposition products are N ₂ and N ¾, and the formation of ¾ cannot be detected. A small amount of ¾ was detected above 200 ^Q C. In addition, in the early days, hydrazine was used for rocket attitude adjustment, and its catalyst was Ir / AL ₂ 0 ₃ (TJJenning et al, US Patent 3503212, 1970; Greer et al, J. Spacecraft and Rockets, 1971, 8, 105- 110), the reaction products are N ₂ and NH ₃ . Thermodynamic data indicate that hydrazine decomposes at room temperature It is possible for N ₂ and ¾, but so far, there have been no reports that hydrazine can be selectively decomposed into ¾ and N ₂ on the catalyst at room temperature. OBJECTS OF THE INVENTION An object of the present invention is to provide a novel catalyst which can effectively solve the above problems, which can decompose hydrazine into hydrogen and nitrogen with high selectivity at room temperature. The purpose of the present invention is briefly described as follows: The composition formula of the catalyst can be expressed as: XYC, where X is Fe, Co, Ni, Cu, Zn, Ru, Rl, Pd, In, Os, Ir, Pt, Au metal element, Y is a perovskite-type or fluorite-type or goethite-type composite oxide, C is a nano-carbon black, X may be one or more metals, and europium is one of three types of oxides Species, C can be added or not added.

The above catalysts can be divided into two types: supported type and mixed type: The general formula of the supported type is expressed as χ / γ, where X is Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, In, Os , Ir, Pt, Au metal elements, Y is a perovskite-type or fluorite-type or goethite-type composite oxide, X may be one or more metals, and Y is one of three types of oxides , The loading of X on Y is 0.5 ^ 20%; the composition formula of the mixed type is expressed as (X / C) _a + Y _b , where X is Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, In, (Ir, Pt, Au metal elements, C is nano carbon black, Y is perovskite or fluorite or goethite type composite oxide, X may be one or more metals, Y It is one of three types of oxides, and the loading amount of X on C is 0.5 to 40%. A, b are the masses of two kinds of X / C and Y, and the ratio a:

 In the present invention, the preferred component for the first type of catalyst is between 1 and 10%, and the preferred component for the second type of catalyst is between 10 and 25%, l> a: b> 0.1.

Many conventional and advanced catalyst preparation methods can be used for the above catalyst preparation. For X / Y catalysts, including metal salt solution impregnation-calcination-reduction method; impregnation-reduction-drying method, metal carbonyl compound thermal decomposition chemical deposition method, Grinding-roasting-reduction method. The (X / C) _a + Y _b type catalyst preparation method can be divided into two steps: The first step is the preparation of X / C, including metal salt solution impregnation-roasting-reduction method; impregnation-reduction dry method, gold carbonyl Chemical decomposition of chemical compounds Product method, grinding-calcination-reduction method. The second step is the mixing of X / C and Y, including mechanical mixing method, grinding method, grinding-ultrasonic vibration method.

 Preparation method of supported catalyst: First, the sol-gel method (using EDTA and citric acid as co-complexing agents, using soluble metal salts as starting materials, and hexanediol and glycerol as dispersants is used. Stir at 70-90 ° C to form a transparent colloid. The colloid is cured at 100-150 ° C, pre-baked at 250-350 ° C for 1-10 hours, and finally calcined at 1000-1400 ° C for 1-100 hours.) Or solid grinding method (using metal nitrate as raw material, first mixing and grinding thoroughly, then firing at 1000-1400 ° C, taking out every 1-5 hours, then grinding and firing, repeated 5-10 times) to prepare calcium titanium Mineral or fluorite or goethite type composite oxide, then add ethanol or water, formaldehyde, KOH, and the soluble metal salt or acid solution to be supported, and stir at 20 ~ 60 ° C for 1 ~ 4 hours , Filter or stand and pour the upper solution, rinse with water to make the pH reach 7, and then dry at 8 (150 ° C).

Preparation method of mixed catalyst: Disperse nano carbon black with ethanol, then add formaldehyde, KOH and required metal soluble salt, stir at 20 60 ^Q C for 14 hours, filter or leave to pour the upper solution, rinse with water The PH value reaches 7, and it is dried at 80 ~ 150 ° C to obtain X / C. X / C and perovskite-type or fluorite-type or goethite-type composite oxides obtained during the preparation of a supported catalyst are mixed and ground, and then the mixed solid is immersed in a distilled aqueous solution for 0.1 to 3 hours under ultrasonic vibration. 80 ~ 150 ° C.

The gas produced by the catalyst of the present invention after decomposing pure hydrazine or hydrazine hydrate at normal temperature can be used as a hydrogen source for a proton exchange membrane fuel cell. Air breathing at normal temperature can achieve a single cell voltage of 0.8V and a current density of 1.50mA / cm ² .

 In addition, the above-mentioned hydrogen can be used as a hydrogen source in metal processing.

Compared with the existing catalyst materials for hydrazine decomposition, the catalyst provided by the present invention can decompose hydrazine or hydrazine hydrate with high selectivity to generate hydrogen gas at normal temperature. Selective. The selectivity of hydrogen is represented by S, S-2 [H ₂ ] X100 / 2 [H ₂ ] +3 [NH ₃ ] o

Temp (° C) S Pd7 La _{0. 2} Sr _{0. 8} Co ₂ Fe _{0. 8} O ₃ 25 65

 50 80

 Pt / Lao.2Sro.8Coo.2Feo.gO3 25 70

 0 50 90

 25 20

 〇 50 25

 W / Lao.2Sro.8Coo.2Feo.8O3 25 30

 50 40

Rh Ba _{0. 2} Sr ₈ Co _{0. 2} Fe ₀ , _s O ₃ 25 50

 50 60

 Fe / Bao.2Sro.8C00 Feo.8O3 25 10

 50 20 From the above table data, it can be seen that when using the catalyst of the present invention for hydrazine decomposition, the selectivity of hydrogen can reach 92%. This shows that this series of catalysts have high hydrogen selectivity. BRIEF DESCRIPTION OF THE DRAWINGS The present invention is described in detail below with reference to specific embodiments and drawings:

Figure 1 shows Bao. ₅ Sr (). ₅ Co. . ₆ Fe. . ₄ Ow powder diffraction XRD pattern.

 FIG. 2 is a schematic diagram of an application example (a fuel cell using hydrogen produced by decomposition of hydrazine) as a raw material.

 Fig. 3 is a polarization curve of a proton membrane fuel cell test unit using hydrogen produced by the decomposition of hydrazine as a hydrogen source on an evaluation device. (Operating conditions: the pressure of ¾ is 0.1 MPa, the flow rate is 50 ml / min, the pressure of air is 0.1 MPa, and the battery temperature is 90 ° C.) Detailed description Example 1 Supported catalyst and preparation method thereof

The supported catalyst has the general formula (X / C) _a + Y _b , where X is Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, In, Os, Ir, Pt, Au, C is nano carbon black, Y is one of three types of oxide rhenium, and the loading of X on C is 0.540%. a, b are two masses of X / C and Y, Its ratio a: b = 0. 10. The catalyst composition of this embodiment is: (lOroPt / Q ^ CBao.sSro.sCoo.eFeo ^ Os.s). Its preparation method is as follows:

The perovskite-type Ba _a5 Sr was prepared by complex method. . ₅ Co. . ₆ Fe. . ₄ 0 ₃ _ _s oxide. Weigh 70 g of EDTA acid and dissolve it in 200 liters of concentrated ammonia water under heating, add 0.1mol Ba (O ₃ ) ₂ crystals, heat to dissolve, and then add 0.1 mol Sr (N0 ₃ ) ₂ , 0.12mol Co (N0 ₃ ) ₂ , 0.08 A mixed solution of mol Fe (N0 ₃ ) ₃ is heated and stirred at 80 ° C. As the water evaporates, a transparent hot-melt fuchsia colloid is obtained. The colloid is cured at 120 ° C for several hours, and then 300 ° C. Pre-baking for 3 hours, and finally baking in a muffle furnace at 950 ° C for 7 hours to obtain a black powder. XRD powder diffraction measurement showed that a pure phase perovskite structure was formed, as shown in Figure 1. The BET specific surface area measurement showed that the specific surface area of the powder was 50 m2 / g. The XR diffraction peak half-width method calculates the grain size of the powder to be 15-40 nm. After mixing 1.8 g of XC-72 carbon powder with 700 ml of ethanol and dispersing it with ultrasonic waves, 0.54 g of ¾PtCl _{4 and} 120 ml of 33% formaldehyde were introduced into the mouth, and placed in a 80 ° C constant temperature water bath. After stirring for 1 hour, 240 g of a 50% KOH solution was added dropwise and stirred for 20 min. After the reaction is completed, wait for the solution to clarify, pour out the upper supernatant, and wash it twice with deionized water to wash off the K ⁺ and Cl- in the solution until the pH of the solution is about 7. Bake it in an oven at 80 ° C for 3 h and 120 ° C for 3 hours to obtain Pt / C. The / C with the same quality _{Ba 0. 5 Sr 5 Co Q} , 6 Fe 4 O ^ mixed and ground, at 15Mpa pressure tableted, and then crushed to 40-60 mesh particles, i.e., to obtain the finished catalyst. Example 2 Mixed catalyst and preparation method thereof

The general formula of the mixed catalyst is: X / Y, where X is Fe, Co, Ni, Cu, Zn, Ru, Rh ₃ Pd _; In, Os, Ir, Pt, Au metal elements, Y is perovskite or For fluorite-type or goethite-type composite oxides, X may be one or more metals, Y is one of three types of oxides, and the loading amount of X on Y is 0.5 to 20%. The catalyst composition of this embodiment is: 10% Pt / La ₂ Ba. , ₈ Co ₃ Fe. . ₇ O _s . Its preparation method is as follows:

The perovskite-type La ₂ Ba _{Q. 8} Co ₃ Fe ₇ O _{s was} prepared by the complex method, 70 g of EDTA acid was weighed and dissolved in 200 ml of concentrated ammonia water, and 0,04 mol La (N0 ₃ ) _{3 was} 0.16 mol. Ba (NO ₃ ) ₂ , 0.06 mol Co (NO ₃ ) ₂ , Fe (NO ₃ ) _{3 were} added to the solution, stirred at 80 ° C as the water evaporated to obtain a colloid, and the colloid was cured at 120 ° C. For thousands of hours, then pre-baking at 300 ° C for 2 hours, and finally baking in a muffle furnace at 1050 ° C for 10 hours Get powder. Add 0.9g La ₂ Ba. . ₈ Co. . ₃ Fe. ₇ Os was poured into 350 ml of ethanol solvent. After dispersing uniformly with ultrasonic waves, 0.27 g of ¾PtCl ₄ and 60 ml of 33% formaldehyde were added, and placed in a constant temperature water bath at 80 ° C, stirred for 1 hour, and then dropped into 50%. 60 grams of KOH solution, stirred 20mm. After finishing, wait for the solution to clarify, pour out the supernatant, rinse with deionized water twice, clarify, and pour out the supernatant. Repeat this several times to remove K ⁺ and CI— from the solution, until the pH of the solution is reached. It is around 7. The catalyst was baked in an oven at 80 ° C for 3 hours and at 120 ° C for 3 hours. Tablet and crush into 40-60 mesh particles to obtain the finished catalyst. Application examples of the present invention

为水合肼催化剂， 在如图 2的反应器中 产生氢气提供给燃料电池。 图中 1为燃料电池， 2为导气管， 3为催化反 应罐， 4 为水合肼， 5 为催化剂。 在常温下进行反应， 加入 0.03g Lao.₂Sr₀.₈Co₀.₂Fe₀.₈O_s+Pt/C催化剂， La₀.₂Sr₀._sCo_a2Fe₀,₈Os与 Pt/C两物质的质 量比为 1 :1。 肼分解产生的 1¾进入燃料电池， 测得单电池电压为 0.8V，电 流密度为 150mA/cm²。 电池的性能曲线如图 3。催化反应 1周， 没有发现 电池性能有明显的变化。 To

For a hydrazine catalyst, hydrogen is produced in a reactor as shown in FIG. 2 and supplied to a fuel cell. In the figure, 1 is a fuel cell, 2 is an air pipe, 3 is a catalytic reaction tank, 4 is hydrazine hydrate, and 5 is a catalyst. The reaction was carried out at normal temperature, and 0.03 g of Lao. ₂ Sr _{0. 8} Co _{0. 2} Fe _{0. 8} O _s + Pt / C catalyst was added, La _{0. 2} Sr _{0. S} Co _a2 Fe ₀ , ₈ Os and Pt / The mass ratio of the two substances C is 1: 1. The 1¾ produced by the decomposition of hydrazine enters the fuel cell, and the measured single cell voltage is 0.8V and the current density is 150mA / cm ² . The performance curve of the battery is shown in Figure 3. After 1 week of catalytic reaction, no significant change in battery performance was found.

Claims

Rights request 1. A catalyst for the preparation and application of a hydrazine decomposition catalyst, characterized in that the composition of the catalyst is as follows:  XYC, where X is Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, In, Os, Ir, Pt, Au metal elements, Y is perovskite or fluorite or goethite composite Oxide, c is nano carbon black, X may be one or more metals, rhenium is one of three types of oxides, c may be added or not added.  2. The catalyst according to claim 1, wherein the metal-supported composition is as follows:  Χ / Υ, where X is Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, In, Os, Ir, Pt, Au metal elements, Y is perovskite or fluorite or goethite Type composite oxide, X may be one or several metals, rhenium is one of three types of oxides, and the loading of X on rhenium is 0.5 ^ 20%. 3. The catalyst according to claim 1, characterized in that the composition of the mixed type is as follows: (X / C) _a + Y _b , where X is Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd , In, Os, Ir, Pt, Au metal element, C is nano carbon black, Y is one of three types of oxides, and the loading amount of X on C is 0.5 to 40%. a, b are two kinds of X / C and Y masses, and their ratios are a: b = 0.1 ~ 10.  4. A method for preparing a catalyst according to claim 2, characterized by: first using a sol-gel method (using EDTA and citric acid as a common complexing agent, using a soluble metal salt as a starting material, Alcohol and glycerin are dispersants. The system is stirred at a constant temperature of 70-90 ° C to form a transparent colloid. The colloid is cured at 100-150 ° C, pre-baked at 250-350 ° C for 1-10 hours, and finally at 1000. Roasting at -1400 ° C for 1-100 hours) or solid grinding method (using metal nitrate as raw material, first mixing and grinding thoroughly, then baking at 1000-1400 ° C, taking out every 1-5 hours and then fully grinding Baking, repeated 5-10 times) to prepare perovskite-type or fluorite-type or goethite-type composite oxide, and then add ethanol or water, formaldehyde, KOH, and the soluble metal salt or acid solution to be carried, Stir at 20 ~ 60 ° C for 1 ~ 4 hours, filter or leave to pour the upper solution, rinse with water to make the Hi value reach 7, then dry at 80 ~ 150 ° C. 5. A method for preparing a catalyst as claimed in claim 3, characterized in that: nano carbon black is dispersed with ethanol, and then formaldehyde, KOH and a desired metal soluble salt are added, and the mixture is stirred at 20 to 60 ° C. 1 ~ 4 hours, filter or leave to pour the upper solution, rinse with water to make PH The value reaches 7, and it is dried at 80 150 ° C to obtain X / C. 3h。 X / C and perovskite-type or fluorite-type or goethite-type composite oxide prepared in accordance with the method of claim 3 mixed grinding, and then the mixed solid was immersed in a distilled aqueous solution of ultrasonic vibration O. 3h , Baking at 80-150 ° C.  6. A catalyst according to claim 1 or 2 or 3, characterized in that the catalyst can be used for generating a hydrogen source of a proton exchange membrane fuel cell.