CN102390805A - Hydrogen production composition and preparation method thereof, and method for preparing hydrogen - Google Patents

Abstract

The invention discloses a hydrogen production composition and a preparation method thereof, and a method for preparing hydrogen. The hydrogen production composition is formed by mixing a metal powder body, an activating agent and an additive, wherein the metal powder body is a mixture of one or more than two of aluminum powder, magnesium powder and zinc powder; the activating agent is a mixture of one or more than two of sodium chloride, potassium chloride and sodium fluoride; and the additive is a mixture of one or more of calcium hydroxide, barium hydroxide and calcium chloride. In the hydrogen production method, the hydrogen production quantity, the hydrogen production speed and/or the hydrogen production time are controlled by changing a composition proportion of the hydrogen production composition and/or changing a proportion of the hydrogen production composition to water. The hydrogen production composition is convenient to use and preserve, low in cost, and nontoxic and harmless; and on-site hydrogen supply and enduring hydrogen supply in which the hydrogen production quantity and the hydrogen production speed can be controlled can be realized.

Description

A kind of hydrogen production composition and its preparation method and hydrogen production method

technical field

The invention relates to the technical field of hydrogen energy, and mainly relates to a method for producing hydrogen by spontaneous hydrolysis of a metal powder composition.

Background technique

Hydrogen is a very promising renewable clean energy. Compared with other energy sources, hydrogen energy has a very obvious advantage, because hydrogen has a high energy density, and the heat energy released by hydrogen per unit mass is three times that of gasoline. Moreover, the only product of the hydrogen-oxygen reaction is water, which does not negatively impact the environment. In particular, the advent of fuel cells and hydrogen engines that use hydrogen as a raw material has brought about a profound revolution in the automotive industry worldwide. To realize the widespread use of hydrogen energy, two problems must first be solved: 1. On-site supply of hydrogen; 2. Storage and transportation of hydrogen. At present, the commonly used hydrogen production methods include electrolysis of water to produce hydrogen, fossil energy to produce hydrogen, biological hydrogen to produce hydrogen, hydrocarbon decomposition to produce hydrogen, ammonia cracking to produce hydrogen, hydrogen sulfide to decompose hydrogen to produce hydrogen, solar direct photoelectric hydrogen to produce hydrogen, radiation catalyst to produce hydrogen, Electron resonance cracking water, hydride hydrolysis hydrogen production and so on. The main hydrogen storage methods include high-pressure gaseous hydrogen storage, liquefied hydrogen storage, metal oxide hydrogen storage, carbonaceous adsorption hydrogen storage and chemical hydride hydrogen storage.

Hydrogen is an efficient fuel for proton exchange membrane fuel cells. However, there are still big problems in the industrial structure of hydrogen production, transportation and storage. Especially for the application of portable fuel cells, the establishment of on-site hydrogen production and hydrogen supply systems is very urgent. Metal hydride hydrogen storage technology is a miniaturized hydrogen storage technology method. Although this hydrogen storage method has the advantages of good reversibility of hydrogen charging and discharging and long cycle life, due to the high density of metals, the hydrogen storage capacity is low. 1. Hydrogen storage alloys are easy to pulverize, and the hydrogen storage mass fraction of most metals is 1.5%~3%, which cannot meet the practical requirements. In the existing chemical hydrogen production technology, magnesium hydride is one of the hydrogen production materials. It can be hydrolyzed when it meets water, the reaction rate is fast, and it has very good hydrogen desorption kinetic properties. However, the hydrolysis reaction of magnesium hydride is very intense, the rate of hydrogen production is difficult to control, and it can spontaneously combust when exposed to air, which is dangerous and not conducive to storage. Moreover, magnesium hydride is expensive and the cost of hydrogen production is high.

Borohydride is a class of chemical hydrogen storage materials. Taking sodium borohydride as an example, when it was used as a reducing agent in the 1950s, people recognized its ability to produce hydrogen by hydrolysis and utilized it. As a good hydrogen storage material, sodium borohydride can be stored stably under certain conditions. It has a long half-life and can exist stably when alkali is added. At present, the method of hydrogen production by hydrolysis of borohydride mainly utilizes catalyst decomposition. In order to improve the hydrogen production effect, the catalyst is usually loaded on the substrate with high specific surface area, but this method still has great limitations: 1. The process of loading the catalyst on the substrate is complicated, and at the same time, it will 2. The adhesion of the catalyst on the substrate is poor, because the hydrogen generated during the reaction will continuously impact the catalyst on the substrate, causing the catalyst to fall off from the substrate and affect the effect of the reaction ; 3. The borohydride solution needs to be stabilized with a strong base first, which is not only difficult in practical application, but also easily causes problems such as alkali climbing, adhesion, and corrosion; 4. The borohydride will continuously generate metaborate during the reaction process. For high-concentration borohydride solutions, with the continuous consumption of water during the hydrolysis reaction, metaborate will exist in the solution in the form of colloids. These colloids will cover the surface of the substrate, inhibit the catalytic effect of the catalyst, and make the reaction The rate decays quickly, making it difficult to achieve large-scale stable hydrogen production [E.Y. Marrero-Alfonso, et al., Int. J. Hydrogen Energy, 2007, 32, 4723-4730].

Chinese patent [publication number CN 101568487A] discloses a hydrogen production composition, which involves aluminum powder (alumina powder), calcium oxide, sodium hydroxide, chloride and other components. This composition can produce hydrogen quickly, but the rate of hydrogen production is difficult to control. Due to the addition of strong alkali components for dissolving aluminum hydroxide, the pH value of the solution is relatively high; due to the addition of calcium oxide, the reaction system generates serious heat, because the dissolution of calcium oxide releases a large amount of heat, etc., resulting in inconvenient use. Chinese patent application [Application No. 200810010747.X, 200810229173.5] discloses a formula for producing hydrogen by dehydrating aluminum, which is made by mixing aluminum halide and aluminum powder. This recipe needs a certain temperature to start, so it needs an auxiliary heating device, which makes it difficult to use portablely. the

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the existing metal powder hydrogen production technology, and provide a hydrogen production composition and its preparation method and hydrogen production method. The present invention can realize convenient, controllable and highly stable on-site supply hydrogen.

The object of the present invention is achieved through the following technical solutions:

A hydrogen production composition obtained by mixing a metal powder, an activator and an additive, the metal powder being one or a mixture of two or more of aluminum powder, magnesium powder or zinc powder; the activator is One or more mixtures of sodium chloride, potassium chloride or sodium fluoride; the additive is one or more mixtures of calcium hydroxide, barium hydroxide or calcium chloride.

As a technical solution for further optimization of the above-mentioned hydrogen production composition, the metal powder accounts for 50-90% by weight of the composition; the activator accounts for 0.1-20% by weight of the composition; The weight ratio of the substance is 0.1-30%.

As a technical solution for further optimization of the above-mentioned hydrogen-generating composition, the metal powder, activator and additive are uniformly mixed by ball milling to obtain the hydrogen-generating composition.

In the hydrogen production method of the above hydrogen production composition, adding the hydrogen production composition into water can stably generate hydrogen.

As a technical solution for further optimizing the hydrogen production method of the above-mentioned hydrogen-producing composition, it can control the amount of hydrogen produced, the rate of hydrogen production and/or by changing the composition ratio of the hydrogen-producing composition and/or changing the ratio of the hydrogen-producing composition to water or hydrogen production time.

As a technical solution for further optimizing the hydrogen production method of the above hydrogen production composition, the weight ratio of the metal powder to the composition is 50-99%.

As a technical solution for further optimizing the hydrogen production method of the above hydrogen production composition, the activator accounts for 0.5-20% by weight of the composition.

As a technical solution for further optimizing the hydrogen production method of the above hydrogen production composition, the weight ratio of the additive to the composition is 0.5-30%.

As a technical solution for further optimizing the hydrogen production method of the above-mentioned hydrogen-producing composition, the weight ratio of the hydrogen-producing composition to water is 1:200-1:10.

Compared with the prior art, the present invention has the following advantages: 1) The measures for activating the metal surface are different. Metals such as aluminum have the ability to self-decompose to produce hydrogen in aqueous solution, but because the product such as aluminum hydroxide forms a surface film, which hinders the further progress of the reaction, the hydrogen production rate of pure aluminum in water is very slow. The principle of the above-mentioned several inventions is to utilize alkali (such as sodium hydroxide) to dissolve aluminum hydroxide, because aluminum hydroxide is an amphoteric compound. However, the addition of alkali results in a higher pH of the solution. Especially when used in proton exchange membrane fuel cells, alkaline components need to be removed, which is inconvenient to use. The starting point of the invention is to add components capable of corroding and destroying the aluminum hydroxide film in the composition, so that the aluminum is constantly in an activated state. And this ingredient is safer, cheaper, non-toxic and harmless than alkali. 2) The temperature can be effectively controlled. The heating of the hydrogen production reaction system using the alkaline formula is very serious, and increasing the temperature can increase the reaction speed, but there are safety hazards in use. The invention can conveniently control the temperature by changing the amount of additives and water. 3) The rate and time of hydrogen production can be effectively controlled by selecting an appropriate proportion of components. 4) The hydrogen production composition of the present invention does not absorb moisture in the air, and can be packed into bags with non-woven fabrics, etc., which are very convenient to use and store. 5) On-site hydrogen supply and long-term hydrogen supply can be realized. The invention also has the advantages that the hydrogen production device used for hydrogen production by using the hydrogen production composition is simple, has low requirements on water, and can be reused. The aqueous solution does not need to add alkali to be stable like sodium borohydride, and it is easy to replace the solution. Moreover, in the application of large-scale hydrogen production, the product is easy to recover, thereby saving costs.

Detailed ways

Example 1

The aluminum powder accounting for 99% of the raw material mass fraction was mixed with 0.5% sodium chloride and 0.5% calcium hydroxide, and ball milled for 1 hour to obtain a hydrogen-producing composition. the

Example 2

Mix aluminum powder accounting for 50% of the mass fraction of raw materials with 20% sodium chloride and 30% calcium hydroxide, and ball mill for 1 hour to obtain a hydrogen-producing composition. It is packaged into a bag with non-woven fabric, soaked in water 10 times the mass of the hydrogen production composition, and can continuously produce hydrogen at a speed of 5 liters per minute.

Example 3

Mix 90% aluminum powder with 9.9% sodium chloride and 0.1% calcium hydroxide, and ball mill for 1 hour to obtain a hydrogen-producing composition. It is packaged into a bag with non-woven fabric, soaked in water 200 times the mass of the hydrogen production composition, and can continuously produce hydrogen at a rate of 0.5 liters per minute.

Example 4

The aluminum powder accounting for 90% of the raw material mass fraction was mixed with 0.1% sodium chloride, 6% calcium chloride and 3.9% calcium hydroxide, and ball milled for 1 hour to obtain a hydrogen-producing composition. It is packaged into a bag with non-woven fabric, soaked in water 50 times the mass of the hydrogen production composition, and can continuously produce hydrogen at a rate of 1 liter/min.

Example 5

Mix 15 g of aluminum powder with 0.2 g of sodium chloride, 1 g of calcium chloride and 0.2 g of calcium hydroxide, and ball mill for 1 hour to obtain a hydrogen-producing composition. It is packaged into a bag with non-woven fabric, soaked in 300 ml of water, and can continuously produce hydrogen at a rate of 50 ml/min for more than 4 hours.

Example 6

Mix 30 grams of aluminum powder with 2 grams of sodium chloride and 1.5 grams of calcium chloride, and ball mill for 1 hour to obtain a hydrogen-producing composition. It is packaged into a bag with non-woven fabric, soaked in 500 ml of water, and can continuously produce hydrogen at a rate of 600 ml/min for 1 hour.

Example 7

The calcium hydroxide in Examples 1-4 was replaced by barium hydroxide, and ball milled for 1 hour to obtain a hydrogen-producing composition.

Example 8

The sodium chloride in Example 1-4 was replaced with potassium chloride, and ball milled for 1 hour to obtain a hydrogen-producing composition.

Example 9

The sodium chloride in Examples 1-4 was replaced with sodium fluoride, and ball milled for 1 hour to obtain a hydrogen-producing composition. the

Example 10

The aluminum in Examples 1-4 and 7-9 was replaced by magnesium, and ball milled for 1 hour to obtain a hydrogen-producing composition.

Example 11

The aluminum in Examples 1-4 and 7-9 was replaced with zinc, and ball milled for 1 hour to obtain a hydrogen-producing composition.

Claims (9)

1. A hydrogen production composition, characterized in that it is obtained by mixing metal powder, an activator and an additive, and the metal powder is one or a mixture of two or more of aluminum powder, magnesium powder or zinc powder; The activator is one or a mixture of two or more of sodium chloride, potassium chloride or sodium fluoride; the additive is one or one of calcium hydroxide, barium hydroxide or calcium chloride a mixture of the above. 2. The hydrogen production composition according to claim 1, characterized in that the metal powder accounts for 50-90% by weight of the composition; the activator accounts for 0.1-20% by weight of the composition; The additive accounts for 0.1-30% by weight of the composition. 3. The method for preparing the hydrogen-producing composition according to claim 1, characterized in that the metal powder, activator and additive are mixed uniformly by ball milling to obtain the hydrogen-producing composition. 4. The method for producing hydrogen using the hydrogen-producing composition according to claim 1, characterized in that the hydrogen-producing composition can be stably generated by adding the hydrogen-producing composition to water. 5. The hydrogen production method according to claim 4, characterized in that by changing the composition ratio of the hydrogen production composition and/or changing the ratio of the hydrogen production composition to water, the amount of hydrogen production, the rate of hydrogen production and/or the production of hydrogen are controlled. hydrogen time. 6. The hydrogen production method according to claim 5, characterized in that the weight ratio of the metal powder to the composition is 50-99%. 7. The hydrogen production method according to claim 5, characterized in that the weight ratio of the activator to the composition is 0.5-20%. 8. The hydrogen production method according to claim 5, characterized in that the weight ratio of the additive to the composition is 0.5-30%. 9. The hydrogen production method according to claim 5, characterized in that the weight ratio of the hydrogen production composition to water is 1:200-1:10.