Sponge carrier catalyst for catalytic hydrolysis hydrogen production and preparation method and application thereof
阅读说明：本技术 一种催化水解制氢的海绵载体催化剂及其制备方法和应用 (Sponge carrier catalyst for catalytic hydrolysis hydrogen production and preparation method and application thereof ) 是由 邓霁峰 谢镭 郑捷 李星国 刘啸 时雨 于 2020-08-07 设计创作，主要内容包括：本发明属于储氢技术领域和燃料电池领域,具体涉及一种基于高分子海绵负载过渡金属基催化剂及其制备方法和在催化NaBH<Sub>4</Sub>水解制氢中的应用。该催化剂的载体为海绵,催化剂活性组分为过渡金属,过渡金属与海绵的质量比为1：1～100,所述的海绵其表面带有含氧基团。过渡金属与高分子海绵载体通过化学键合作用形成较强的连接,在气体和液体冲刷、海绵挤压过程中负载的过渡金属均不会脱落,有效提高NaBH<Sub>4</Sub>水解制氢系统的性能。本发明基于海绵具有强吸水性,使得本发明的海绵载体催化剂在简易装置制氢应用过程中的绝大部分时间体系中不存在流动的液态水,提高了装置使用便捷性。(The invention belongs to the technical field of hydrogen storage and the field of fuel cells, and particularly relates to a transition metal-based catalyst based on polymer sponge loading, a preparation method thereof and application thereof in catalyzing NaBH 4 Application in hydrolysis hydrogen production. The carrier of the catalyst is sponge, the active component of the catalyst is transition metal, and the mass ratio of the transition metal to the sponge is 1: 1-100, wherein the surface of the sponge is provided with an oxygen-containing group. The transition metal and the macromolecular sponge carrier form stronger connection through chemical bonding, and the transition metal loaded in the processes of gas and liquid scouring and sponge extrusion is not allCan fall off and effectively improve NaBH 4 Performance of a hydrolysis hydrogen production system. Based on the fact that sponge has strong water absorption, the sponge carrier catalyst provided by the invention has no flowing liquid water in most time systems in the application process of hydrogen production of a simple device, and the use convenience of the device is improved.)
1. A sponge carrier catalyst for preparing hydrogen by catalytic hydrolysis is characterized in that: the catalyst comprises a carrier of sponge and an active component of a catalyst of transition metal, wherein the mass ratio of the transition metal to the sponge is 1: 1-100, wherein the surface of the sponge is provided with an oxygen-containing group.
2. The sponge carrier catalyst for catalytic hydrolysis hydrogen production according to claim 1, wherein: the sponge is polyvinyl formal sponge.
3. The sponge carrier catalyst for catalytic hydrolysis hydrogen production according to claim 2, characterized in that: the catalyst is prepared by the following steps:
cutting the polyvinyl formal sponge into a required shape;
preparing a transition metal salt aqueous solution, putting polyvinyl formal sponge, extruding and dipping to ensure that the sponge fully absorbs the transition metal salt aqueous solution;
putting the polyvinyl formal sponge which fully absorbs the aqueous solution of the transition metal salt into an oven, and drying in vacuum;
putting the dried polyvinyl formal sponge into NaBH4And carrying out reduction reaction in the aqueous solution, and after the reaction is finished, washing with water and extruding to obtain the sponge carrier catalyst for hydrogen production by catalytic hydrolysis.
4. The sponge carrier catalyst for catalytic hydrolysis hydrogen production according to claim 3, wherein: the mass percentage of the transition metal salt aqueous solution is 2-15%, and the NaBH is added4The mass percentage of the aqueous solution is 1-10%, and the transition metal salt solution is selected from one of nitrate or chloride aqueous solutions of Co, Ni, Fe and Mn; the vacuum drying temperature is 60-120 ℃, and the vacuum drying time is 6-24 h.
5. The sponge carrier catalyst for catalytic hydrolysis hydrogen production according to claim 1, wherein: the sponge is subjected to plasma modification, so that oxygen-containing functional groups are introduced to the surface of the sponge fiber.
6. The sponge carrier catalyst for catalytic hydrolysis hydrogen production according to claim 5, wherein: the plasma modification method comprises the following steps: cutting the sponge into small pieces, and placing the small pieces in a radio frequency discharge plasma reactor for modification, wherein the modification temperature is 20-150 ℃, and the reactor pressure is 1-1000 Pa; the atmosphere is air containing water vapor, and the relative humidity is 0-100%; the total flow rate of the gas is controlled to be 50-10000 mL/min, the power of the radio frequency discharge plasma is controlled to be 30-1000W, and the processing time is controlled to be 10-120 min.
7. The sponge supported catalyst for catalytic hydrolysis hydrogen production according to claim 5 or 6, wherein: the sponge is melamine sponge.
8. A method of preparing a sponge supported catalyst for the production of hydrogen by catalytic hydrolysis according to claim 1, wherein: the preparation method comprises the following steps:
transition metal salt impregnation loading
Soaking sponge with surface oxygen-containing groups into aqueous solution of transition metal salt to prepare the sponge loaded with the transition metal salt, wherein the mass percentage of the transition metal salt solution is 0.05-50%, and the ratio of the apparent volume of the sponge to the volume of the transition metal salt solution is 1: 1-10 ℃, and the dipping temperature is 10-100 ℃;
2) preparation of sponge-supported catalyst
Immersing the sponge loaded with the transition metal salt prepared in the step 1) into NaBH4In the solution, reducing the transition metal salt into transition metal or boride of transition metal to obtain the sponge carrier catalyst, wherein NaBH4The mass percentage content of the solution is 0.5-20%, the reaction temperature is 0-80 ℃, and the reaction time is 0.1-6 h.
9. The preparation method of the sponge carrier catalyst for hydrogen production by catalytic hydrolysis according to claim 8, characterized in that: the transition metal salt solution is selected from one of nitrate or chloride aqueous solutions of Co, Ni, Fe and Mn.
10. The use of the sponge supported catalyst for the catalytic hydrolysis of hydrogen as claimed in claim 1, wherein: for catalyzing NaBH4And (3) hydrolyzing to prepare hydrogen.
Technical Field
The invention belongs to the technical field of hydrogen storage and the field of fuel cells, and particularly relates to a transition metal-based catalyst based on polymer sponge loading, a preparation method thereof and application thereof in catalyzing NaBH4Application in hydrolysis hydrogen production.
Background
Hydrogen storage is a key technology for hydrogen fuel cell applications. NaBH4The hydrolysis hydrogen production is an efficient in-situ hydrogen production technology, has the advantages of high theoretical hydrogen storage density, easy control of reaction and the like, and is very suitable for hydrogen supply of medium and small fuel cells.
NaBH4Can form a very stable alkaline aqueous solution, NaBH4Under the catalysis of Co, Ni and other transition metals, NaBH is added into the alkaline aqueous solution4Can be hydrolyzed quickly to release hydrogen. Thus, the common NaBH4The hydrolysis hydrogen production method is to make NaBH4The alkaline aqueous solution of (a) is contacted with a transition metal catalyst such as Co, Ni and the like.
In order to facilitate the recycling of the catalyst, the catalyst is usually loaded on a porous carrier material substrate, and then the loaded catalyst is wholly filled in a fixed bed reactor by controlling NaBH4The rate of entry of the aqueous alkaline solution into the reactor controls the rate of hydrogen generation. The most commonly used catalyst support is porous ceramic, which is usually prepared by mixing a catalyst slurry with the porous ceramic, drying, and sintering at high temperature to support the catalyst on the porous ceramic. The whole hydrogen supply device generally comprises a fuel tank, a water pump and a controller, a reactor, a gas-liquid separation device, a water removal device and the like.
The above conventional NaBH4The hydrolysis hydrogen production technology needs a more complex auxiliary system, and the hydrogen storage density of the system is obviously reduced. In addition, the reactor is provided with a plurality of holesThe ceramic carrier has a large weight, the volume of the reactor cannot be too large in order to increase the hydrogen storage density, and the loading process of the catalyst is also complicated.
In order to reduce the quality of a catalyst carrier, the invention provides NaBH based on a macromolecular sponge4A catalyst. Of course, the subject group of the present invention has proposed a solid hydrolysis hydrogen production material, and patent publication nos.: CN 106495096A, although the technical scheme of the patent also relates to the adoption of sponge and also serves as a carrier, the sponge adopted in the technical scheme of the patent is used for meeting the use requirement that the water guiding speed is high and the adsorption force on water cannot be too strong by virtue of the special water absorption effect of the sponge, and the sponge is added for improving water and NaBH4The degree of uniformity of the contact. In addition, although the preparation method in the patent also involves mixing and drying a transition metal salt solution and melamine sponge, the subject group of the present invention further studies and finds that: only weak physical adsorption exists between melamine sponge and transition metal salt, and NaBH is adopted4The transition metal is likely to fall off from the surface of the melamine sponge during the hydrolysis process, and the positive effects of catalyst recovery and repeated use in the present invention cannot be achieved, and in fact, previous research work on the subject group of the present invention does not involve the strong interaction between the sponge and the transition metal.
The invention develops a sponge carrier catalyst for preparing hydrogen by catalytic hydrolysis for further application on the basis of the technology of the prior patent.
Disclosure of Invention
The invention aims to provide NaBH based on a polymer sponge loaded transition metal base aiming at the problems in the background technology4The transition metal and the macromolecular sponge carrier form stronger connection through chemical bonding, the loaded transition metal can not fall off in the processes of gas and liquid scouring and sponge extrusion, and the NaBH is effectively improved4Performance of a hydrolysis hydrogen production system.
The invention also aims to provide a preparation method of the sponge carrier catalyst for preparing hydrogen by catalytic hydrolysis.
The invention further aims to provide application of the sponge carrier catalyst for preparing hydrogen by catalytic hydrolysis.
The technical scheme adopted for realizing the aim of the invention is as follows: a sponge carrier catalyst for hydrogen production by catalytic hydrolysis is provided, wherein a carrier of the catalyst is sponge, and an active component of the catalyst is transition metal, wherein the mass ratio of the transition metal to the sponge is 1: 1-100, wherein the surface of the sponge is provided with an oxygen-containing group.
Preferably, the sponge of the present invention is a polyvinyl formal sponge.
Further preferably, the catalyst using the polyvinyl formal sponge as the carrier is prepared by the following steps:
1) cutting the polyvinyl formal sponge into a required shape;
2) preparing a transition metal salt aqueous solution, putting polyvinyl formal sponge, extruding and dipping to ensure that the sponge fully absorbs the transition metal salt aqueous solution;
3) putting the polyvinyl formal sponge which fully absorbs the aqueous solution of the transition metal salt into an oven, and drying in vacuum;
4) putting the dried polyvinyl formal sponge into NaBH4And carrying out reduction reaction in the aqueous solution, and after the reaction is finished, washing with water and extruding to obtain the sponge carrier catalyst for hydrogen production by catalytic hydrolysis.
Wherein, the mass percentage content of the transition metal salt aqueous solution is 2 percent to 15 percent, and the NaBH is4The mass percentage of the aqueous solution is 1-10%, the transition metal salt solution is selected from one of nitrate or chloride aqueous solutions of Co, Ni, Fe and Mn, the vacuum drying temperature is 60-120 ℃, and the vacuum drying time is 6-24 h.
Preferably, the sponge of the present invention is subjected to plasma modification treatment to introduce oxygen-containing functional groups to the surface of the sponge fibers.
Further preferably, the plasma modification method comprises: cutting the sponge into small pieces, and placing the small pieces in a radio frequency discharge plasma reactor for modification, wherein the modification temperature is 20-150 ℃, and the reactor pressure is 1-1000 Pa; the atmosphere is air containing water vapor, and the relative humidity is 0-100%; the total flow rate of the gas is controlled to be 50-10000 mL/min, the power of the radio frequency discharge plasma is controlled to be 30-1000W, and the processing time is controlled to be 10-120 min.
More preferably, the sponge is melamine sponge.
The technical scheme adopted for realizing the other purpose of the invention is as follows: a preparation method of a sponge carrier catalyst for hydrogen production by catalytic hydrolysis comprises the following steps:
1) transition metal salt impregnation loading
Soaking sponge with surface oxygen-containing groups into aqueous solution of transition metal salt to prepare the sponge loaded with the transition metal salt, wherein the mass percentage of the transition metal salt solution is 0.05-50%, and the ratio of the apparent volume of the sponge to the volume of the transition metal salt solution is 1: 1-10 ℃, and the dipping temperature is 10-100 ℃;
2) preparation of sponge-supported catalyst
Immersing the sponge loaded with the transition metal salt prepared in the step 1) into NaBH4In the solution, reducing the transition metal salt into transition metal or boride of transition metal to obtain the sponge carrier catalyst, wherein NaBH4The mass percentage content of the solution is 0.5-20%, the reaction temperature is 0-80 ℃, and the reaction time is 0.1-6 h.
More preferably, the transition metal salt solution is selected from one of nitrate or chloride aqueous solutions of Co, Ni, Fe, Mn.
The invention also aims to provide application of the sponge carrier catalyst for preparing hydrogen by catalytic hydrolysis to catalyze NaBH4And (3) hydrolyzing to prepare hydrogen.
Compared with the prior art, the invention has the following advantages:
(1) the invention uses the light sponge as the carrier, greatly reduces the weight of the catalyst, improves the actual hydrogen storage density of the system, and most importantly, further discovers the transition metal-loaded NaBH of the invention4The catalyst comprises the following components: different kinds of sponges as carriers have important influence on the catalytic performance of the catalyst, such as: melamineThe surface of the amine (MF) sponge has no functional group coordinated with transition metal ions, and the surface of the polyvinyl formal (PVF) sponge has an oxygen-containing group which can directly adsorb the transition metal ions, so that the transition metal and the sponge carrier form stronger connection through chemical bonding.
(2) The invention aims at the surface characteristics of the melamine MF sponge, optimizes proper plasma surface modification conditions, enhances the acting force of the melamine MF sponge and transition metal ions, leads the transition metal and the sponge carrier to form stronger connection through chemical bonding, leads the loaded transition metal not to easily fall off in the processes of gas and liquid scouring and sponge extrusion, and effectively improves the NaBH4Performance of a hydrolysis hydrogen production system.
(3) The sponge carrier catalyst prepared by the invention can discharge reaction product solution in a mechanical extrusion mode, and is convenient for recycling the catalyst for multiple times; the sponge carrier catalyst of the invention has simple preparation method, is easy to be processed into different shapes, and can meet the requirements of different types of reaction devices.
(4) Based on the strong water absorption of the sponge, the sponge carrier catalyst provided by the invention has no flowing liquid water in most time systems in the application process of hydrogen production of the simple device, and the use convenience of the device is improved.
Drawings
FIG. 1 is a schematic diagram of the preparation process of the sponge carrier catalyst for hydrogen production by catalytic hydrolysis.
FIG. 2 is an SEM photograph of a sponge supported catalyst framework prepared in example 1 of the present invention.
FIG. 3 is a TEM photograph of a catalyst prepared by a dipping reduction method in example 1 of the present invention.
FIG. 4 shows that the sponge supported catalyst of example 1 of the present invention absorbs 10mL of 10% NaBH4The hydrogen release curve chart of the solution for 5 times of hydrolysis hydrogen production.
Fig. 5 is a schematic diagram of an electric energy output by using a sponge supported catalyst as a hydrogen source to supply hydrogen for a fuel cell in example 1 of the present invention.
FIG. 6 shows a sponge carrier catalyst in example 1 of the present inventionApplication of Agents to NaBH4A reaction device for solution hydrolysis.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments.
The invention relates to a transition metal-based catalyst based on macromolecule sponge load, a preparation method thereof and application thereof in catalyzing NaBH4The application in the hydrolysis hydrogen production, the specific technical scheme of the catalyst preparation and the application is as follows:
1. and (4) selecting a sponge carrier. The sponge carrier needs to be at pH>13 in the alkaline aqueous solution, the stability is good within the range of room temperature to 120 ℃, and the alkaline aqueous solution has a communicated open pore structure, larger porosity and lower apparent density. There are no particular requirements for porosity, pore size and apparent density in principle, but practical applications require a high porosity: (>10 cm3(g) low apparent density<0.1g/cm3) Sponges with better water absorption properties, including but not limited to: polyvinyl formal sponge (PVF), melamine sponge (MF). The size and shape of the sponge carrier are not limited, according to the requirements of practical application.
2. Plasma surface modification of sponge fibers. The purpose is to introduce oxygen-containing functional groups such as-OH, -COOH, C = O, -O-and the like to the surface of the sponge fiber, and improve the adhesion of transition metal ions on the surface of the sponge. The practical application of the subject group finds that: the PVF sponge has more oxygen-containing groups, and the plasma surface modification treatment can be omitted. The plasma modification method comprises the following steps: discharging in oxygen-containing gas (including but not limited to air, oxygen, ozone, water vapor, etc.) can generate high-activity oxygen-containing groups, so that the oxygen-containing groups are introduced to the surface of the sponge.
3. And (4) loading of transition metal. Impregnation of sponge with surface oxygen-containing groups to transition metal salts (e.g., CoCl)2、Ni(NO3)2、FeCl3、MnCl2Etc.) in the aqueous solution, the salt solution concentration is 0.05-50%, the apparent volume of the sponge and the volume ratio of the salt solution are 1: 1-1: 10, the dipping temperature is 10-150 ℃, and the dipping time is 5 min-2 h.
Acid-base or buffer solution can be added to regulate pH in the process of impregnation or hydrothermal synthesis, and surfactant and ligand are added to regulate the shape and size of the loaded transition metal product; the sponge loaded with transition metal is subjected to mechanical extrusion, drying, freeze-drying and other modes to remove the solvent. The loading-drying step can be repeated for multiple times to regulate the loading amount of the transition metal. The oxidation state of the transition metal on the sponge is the same as that of the metal salt, and the transition metal and the sponge form stronger bonding force through the chemical bond of metal-oxygen.
4. And (4) reducing the transition metal. Immersing a transition metal-loaded sponge in NaBH4In solution, the transition metal is reduced to metal or metal boride, and the specific composition of the reduction product is related to the type of metal and the reduction conditions. NaBH4The concentration is 0.5-20%, the reaction temperature is 0-80 ℃, and the reaction time is 0.1-6 h. After reduction, the sponge was sufficiently washed with deionized water. Through transition metal loading and NaBH4Finally, the transition metal catalyst component stably loaded on the sponge accounts for 1 to 100 percent of the mass of the sponge. NaBH used in the preparation of the catalyst4The solution is dilute in concentration and is mainly used for reducing the transition metal salt, and although part of hydrogen is generated, the hydrogen does not influence the total reduction of the transition metal. In practice, a slight excess of sodium borohydride was used to ensure complete reduction of the transition metal. Alternatively, the hydrogen generation rate may be reduced by lowering the reaction temperature, but it is not necessary to completely avoid hydrogen generation.
5. Sponge catalyst catalysis of NaBH4Application of hydrolysis hydrogen production.
The first scheme is as follows: immersing the sponge carrier catalyst in NaBH directly4In solution (2), the apparent volume of the sponge is NaBH420-300% of the volume of the solution, and NaBH is used in the reaction process4Is absorbed into the pores of the sponge and contacts with the catalyst component supported on the sponge to generate hydrogen. NaBH4NaBH containing NaOH can be used4Solution, NaBH4The concentration of the solution is 5 to 30 percent, and the concentration of the NaOH solution is 0.1 to 10 percent; NaBH may also be used4And adding water into the solid for on-site preparation. After use, the mixture is mechanically extrudedNaBH remaining in the sponge4The solution is discharged quickly, and the sponge carrier catalyst can be reused for many times.
Scheme II: the catalyst is used for a traditional fixed bed reactor, and a monolithic sponge catalyst or sponge catalyst particles are filled into the fixed bed reactor to replace a traditional porous ceramic carrier-loaded catalyst. NaBH4The operation and operation of the hydrolysis apparatus are the same as those of the conventional fixed bed reactor.