WO2021143277A1

WO2021143277A1 - Method for storing hydrogen using structure-h hydrate

Info

Publication number: WO2021143277A1
Application number: PCT/CN2020/125061
Authority: WO
Inventors: 王燕鸿; 尹凯东; 樊栓狮; 郎雪梅; 李刚; 王盛龙; 于驰
Original assignee: 华南理工大学
Priority date: 2020-01-15
Filing date: 2020-10-30
Publication date: 2021-07-22
Also published as: ZA202202485B; CN111204706A; CN111204706B

Abstract

Provided is a method for storing hydrogen using a structure-H clathrate hydrate. According to the method, by means of a hydrogenation reaction of an aromatic compound, hydrogen is stored in an alkane product obtained after the hydrogenation in the form of hydrogen protons, and then the alkane product forms a structure-H clathrate hydrate with water to form a cavity, so that hydrogen is encaged in the cavity of the clathrate hydrate. Compared with other hydrogen storage methods, the present method has the advantages of environmental protection, economy, and safety. Compared with conventional hydrate-based hydrogen storage methods, the present method has higher hydrogen storage density and milder conditions.

Description

A method of using H-type hydrate to store hydrogen

Technical field

The present invention belongs to the field of gas hydrate hydrogen storage research, and specifically relates to a method for using H-type hydrate hydrogen storage; the present invention not only uses a hydrate clathrate structure to store hydrogen, but also uses the hydrogenation reaction of organic matter to convert hydrogen to hydrogen. The proton form exists in the hydrate guest molecule.

Background technique

Clathrate hydrates are non-stoichiometric compounds formed by host water molecules and guest gas molecules at low temperature and high pressure. The cavity structure of water molecules connected by hydrogen bonds can trap gas molecules and allow them to stay under stable conditions. At present, people have discovered three kinds of hydrate lattice structures in nature: SI, SII and SH. SI is usually composed of molecules with a radius of 2.0-2.6Å, while SII is composed of molecules with a radius of less than 2Å or greater than 2.8Å. Due to the larger size of the large cage (5 ¹² 6 ⁸ ) in the SH structure, only organic molecules with larger molecular sizes can form SH hydrates.

Hydrogen is considered a green fuel and an ideal resource because people already know that its combustion only produces water and releases more energy than many other fossil fuels. Because hydrogen is the lightest gas, people face difficulties in the process of hydrogen storage and transportation. There are three general hydrogen storage methods: physical methods, chemical methods and other methods. The hydrate method of hydrogen storage does not require high pressure and low temperature as strictly as physical methods, nor does it require excessive chemical materials. As we all know, the hydrate method has the advantages of low cost and high safety. But it can only achieve relatively low storage capacity.

The current hydrate hydrogen storage method requires high pressure, slow gas storage speed, low gas storage density, and gas storage materials cannot be recycled. A practical and single gas storage method is difficult to promote in the industry. Therefore, the present invention proposes a The cage type of organic compound conforms to the hydrogen storage method, which has the advantages of rapid hydrogen storage, mild gas storage conditions, high gas storage density, etc., and allows a gas storage material to store hydrogen in two ways.

Technical solutions

The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for composite hydrogen storage of cage compounds. The present invention has mild conditions, which not only allows hydrogen to be stored in organic matter in the form of hydrogen protons, but also allows hydrogen to be stored in molecular form in the hydrate cage voids, and it is easy to resolve all the hydrogen stored in the hydrate. The characteristics of high hydrogen storage density, safety, environmental protection and easy transportation.

The present invention is realized through the following technical solutions:

A method of using H-type hydrate to store hydrogen includes the following steps:

(1) Put the aromatic compound that can be used for hydrogenation in the reaction kettle, control the temperature of the reaction kettle to 20-90℃, put in the metal catalyst, extract the air from the reaction kettle, and pass in 1.0-5.0MPa hydrogen for 12-14h Afterwards, the reaction mixture in the reactor is subjected to solid-liquid separation to obtain a hydrogenated product after hydrogenation;

(2) Cool down the temperature of the cold bath to -50-20°C, which is required for the formation of H-form hydrate, put the reactor containing pure water and the hydrogenation product in step (1) into the cold bath, and seal the reactor. Take out the air in the reactor and pass in an appropriate amount of methane. When the pressure in the reactor reaches 0.2-40.0MPa, stop the methane flow. After the pressure in the reactor drops and stabilizes, extract the gas in the reactor and pass in hydrogen. When the pressure reaches 1.0-70.0MPa, stop the hydrogen flow, and after the pressure in the reactor drops and stabilizes, the hydrate hydrogen storage ends.

In the present invention, the hydrogen storage method is a combination of chemical hydrogen storage and H-hydrate hydrogen storage.

The molecular weight of the aromatic compound that can be used for hydrogenation is 40-200, preferably 80-150, and the molecular radius is 0.2-1.5 Å, most preferably 0.4-1.0 Å.

The metal nano-catalyst used in the hydrogenation reaction of aromatic compounds is prepared with a carbon-based material as a carrier, and the main body of the catalyst adopts any one or two of Ni, Al, Co, Ru, Rh, Pd or Pt.

The volume ratio of the pure water added to the reaction kettle and the hydrogenation product when the hydrate is formed is 0.5-20, preferably 2.5-6.

In the method of the present invention, the product of step (1) and methane are combined to form a hydrate skeleton, and then the gas in the kettle is extracted to allow methane to escape from the hydrate phase, and then hydrogen is introduced into the reactor to allow hydrogen to diffuse into the hydrate. Holes.

The hydrogen stored in the present invention exists in two or forms: a part of hydrogen forms active hydrogen protons under the presence of a catalyst, and undergoes a hydrogenation reaction with the hydrogenated aromatic compound to form a hydrogenated product with a ring. The hydrogen product has a large molecular radius and can form H-type hydrates with water and methane. After the methane is pumped out, hydrogen can be fed into the empty cage of the H-hydrate to achieve the purpose of further storing hydrogen.

Beneficial effect

The advantages and beneficial effects of the present invention over the prior art:

(1) Hydrogen clathrate compound crystals are milder than hydrogen hydrate formation conditions, with a temperature of -50-20°C and a pressure of 1.0-70.0MPa, thus improving the high pressure conditions required for hydrogen storage of clathrate hydrates (temperature 273K, pressure Up to 200MPa).

(2) Compared with using only clathrate compounds to store hydrogen, the hydrogenation reaction of aromatic compounds allows hydrogen to also exist in the form of hydrogen protons in the guest molecules forming hydrates, and the hydrogen storage density is higher and the efficiency is higher.

(3) From the hydrogenation reaction to the formation of hydrate crystals, the catalysts, aromatic compounds, water and methane can all be recycled.

(4) The hydrogen cage compound has mild hydrogen storage conditions, stores hydrogen in solid form, and is safe to transport.

Embodiments of the present invention

Because the present invention uses methane and hydrogenation products to first form an H-type hydrate framework, the methane consumption can be used to calculate the mass of water in the hydrate and the mass of hydrogenation products, that is, methane: hydrogenation product: water = 5:1: 34. Hydrogen is stored in the hydrate cage and hydrogenation products, so the hydrogen storage calculation formula (1) in the embodiment of the present invention:

△P is the pressure change in the reactor (P ₁ -P ₂ ), V is the volume of the hydrate reactor, T is the temperature in the reactor, R=8.3145Jmol ^-1 K ^-1 .

In this article, the hydrogenation reaction and the formation of hydrates are all used in high pressure reactors.

During the hydrogenation reaction, the temperature of the constant temperature water bath is adjusted, and when the temperature of the water bath reaches 20-90°C, the reaction kettle is immersed in the constant temperature water bath.

During the hydrate formation reaction, put the reaction kettle into a constant temperature cold bath. The inside of the constant temperature cold bath is filled with ethylene glycol, and ethylene glycol is used as a refrigerant. The reaction kettle is immersed in it to maintain a certain temperature (-50-20℃). ). The reactor is connected with a pressure sensor and thermocouple to measure pressure and temperature respectively.

Example 1

(1) Put 30g of toluene in reactor 1, put in Ni/Al catalyst with carbon-based material as the carrier, seal the reactor, and after evacuating the air in the reactor, pass in 4.0MPa hydrogen, and immerse the reactor 1 in a 50℃ After 13 hours of reaction in a constant temperature water bath, the reaction mixture in the reactor was filtered to separate the metal catalyst and the methylcyclohexane product. Among them, the catalyst preparation method refers to Li Xueli, Liu Yunqi, Cui Min, etc. The hydrogenation conversion reaction of toluene on precious metal catalysts[J]. Petroleum Refining and Chemical Industry, 2004, 35(12):18-22.

(2) Put the methylcyclohexane product and 100cm ^{3 of} pure water into the reactor 2, then immerse the reactor in a constant temperature cold bath at 2°C, seal the reactor, draw out the air in the reactor, and pass methane into the reactor. After the internal pressure reaches 5.0MPa, stop the ventilation. After the pressure in the reactor drops and stabilizes, extract the gas from the reactor and pass in hydrogen. When the pressure in the reactor reaches 5.0MPa, stop the ventilation. After the pressure in the reactor drops and stabilizes, the hydrogen is stored. end. The hydrogen storage capacity is calculated according to formula (1). In this embodiment, the hydrogen storage capacity is 2.48 wt%.

When the stored hydrogen is needed, the clathrate hydrate can be resolved to obtain pure hydrogen. The analysis is divided into two steps: the first step is to increase the temperature of the environment where the hydrate is located, so that the temperature of the hydrate is outside the phase equilibrium line, so the hydrogen stored in the form of hydrogen molecules will be resolved; the second step After the liquid phase product methylcyclohexane is decomposed from the hydrate, the methylcyclohexane and Pt/C catalyst are placed in the reactor, and nitrogen is used as the carrier gas and the inert diluent. The reaction temperature is 380℃. The pressure is 0.5MPa, the carrier gas flow rate is 10ml/min, and methylcyclohexane is decomposed into toluene and hydrogen.

Example 2

(1) Put 33g of 1,3-xylene in reactor 1, put in the Ni/Al catalyst with carbon-based material as the carrier, seal the reactor, vent the air in the reactor, and then pass in 4.0MPa hydrogen gas. After being immersed in a constant temperature water bath at 50°C and reacting for 13 hours, the reaction mixture in the reactor was filtered to separate the metal catalyst and 1,3-methylcyclohexane. Among them, the catalyst preparation method refers to Li Xueli, Liu Yunqi, Cui Min, etc. The hydrogenation conversion reaction of toluene on precious metal catalysts[J]. Petroleum Refining and Chemical Industry, 2004, 35(12):18-22.

(2) Put 40cm ^{3 of} 1,3-dimethylcyclohexane and 100cm ^{3 of} pure water into reactor 2, immerse the reactor in a constant temperature cold bath at 2°C, seal the reactor, and extract the air in the reactor. Pour in methane, stop the ventilation when the pressure in the kettle reaches 5.0MPa, and after the pressure in the reactor drops and stabilize, extract the gas from the reactor and feed in hydrogen. When the pressure in the kettle reaches 5.0MPa, stop the ventilation, and the pressure in the reactor will drop. After it stabilizes, the hydrogen storage ends. The hydrogen storage capacity is calculated according to formula (1), and the hydrogen storage capacity in this embodiment is 2.90wt%.

When the stored hydrogen is needed, the clathrate hydrate can be resolved to obtain pure hydrogen. The analysis is divided into two steps: the first step is to increase the temperature of the environment where the hydrate is located, so that the temperature of the hydrate is outside the phase equilibrium line, so the hydrogen stored in the form of hydrogen molecules will be resolved; the second step After the liquid phase product 1,3-dimethylcyclohexane is decomposed from the hydrate, the 1,3-dimethylcyclohexane and Pt/C catalyst are placed in the reactor, and nitrogen is used as the carrier gas and inert Diluent gas, reaction temperature is 380°C, reaction pressure is 0.5MPa, carrier gas flow rate is 10ml/min, 1,3-dimethylcyclohexane is decomposed into 1,3-xylene and hydrogen.

Example 3

(1) Put 33g of 1,2-xylene in reactor 1, put in the Ni/Al catalyst with carbon-based material as the carrier, seal the reactor, vent the air in the reactor, and then pass in 4.0MPa hydrogen. After immersing in a constant temperature water bath at 50°C and reacting for 13 hours, the reaction mixture in the reactor was filtered to separate the metal catalyst and 1,2-dimethylcyclohexane. Among them, the catalyst preparation method refers to Li Xueli, Liu Yunqi, Cui Min, etc. The hydrogenation conversion reaction of toluene on precious metal catalysts[J]. Petroleum Refining and Chemical Industry, 2004, 35(12):18-22.

(2) Put 40cm ^{3 of} 1,2-dimethylcyclohexane and 100cm ^{3 of} pure water into reactor 2, immerse the reactor in a constant temperature cold bath at 2°C, seal the reactor, and extract the air in the reactor. Pour in methane, stop the ventilation when the pressure in the kettle reaches 5.0MPa, and after the pressure in the reactor drops and stabilize, extract the gas from the reactor and feed in hydrogen. When the pressure in the kettle reaches 5.0MPa, stop the ventilation, and the pressure in the reactor will drop. After it stabilizes, the hydrogen storage ends. The hydrogen storage capacity is calculated according to formula (1). In this embodiment, the hydrogen storage capacity is 2.06wt%.

When the stored hydrogen is needed, the clathrate hydrate can be resolved to obtain pure hydrogen. The analysis is divided into two steps: the first step is to increase the temperature of the environment where the hydrate is located, so that the temperature of the hydrate is outside the phase equilibrium line, so the hydrogen stored in the form of hydrogen molecules will be resolved; the second step After decomposing the liquid phase product 1,2-dimethylcyclohexane from hydrate, put 1,2-dimethylcyclohexane and Pt/C catalyst in the reactor, using nitrogen as carrier gas and inert Diluent gas, reaction temperature is 380°C, reaction pressure is 0.5MPa, carrier gas flow rate is 10ml/min, 1,2-dimethylcyclohexane is decomposed into 1,2-xylene and hydrogen.

Claims

A method for hydrogen storage using H-type hydrate is characterized in that it comprises the following steps:

(1) Put the aromatic compounds that can be used for hydrogenation in the reactor, control the temperature of the reactor to 20-90℃, put in the metal catalyst, and pass in 1.0-5.0MPa hydrogen. After 12-14h, the The reaction mixture is subjected to solid-liquid separation to obtain the hydrogenated product after hydrogenation; the aromatic compounds that can be used for hydrogenation include: toluene, p-xylene, 1,2-xylene, 1,3-xylene, 1,2 ,3-Trimethylbenzene, 1,2,4-trimethylbenzene or 1,3,5-trimethylbenzene;

(2) Cool the cold bath to the temperature required for the formation of H-hydrate, put the reactor filled with pure water and the hydrogenation product in step (1) into the cold bath, seal the reactor, and extract the air in the reactor. Feed in methane. When the pressure in the reactor reaches the specified pressure, stop the flow of methane. After the pressure in the reactor drops and stabilizes, draw out the gas in the reactor and pass in hydrogen. When the pressure in the reactor reaches the specified pressure, stop the flow of hydrogen. After the pressure in the reactor drops and stabilizes, the hydrate hydrogen storage ends.
The method for hydrogen storage using H-hydrate hydrate according to claim 1, wherein in step (1), the molecular weight of the aromatic compound that can be used for hydrogenation is 40-200, and the molecular radius is 0.2-1.5 Å.
The method of using H-hydrate hydrogen storage according to claim 1, characterized in that, in step (1), the molecular weight of the aromatic compound that can be used for hydrogenation is 80-150; the molecular radius is 0.4-1.0Å. between.
The method for hydrogen storage using H-hydrate hydrate according to claim 1, wherein in step (1), the metal nanocatalyst is prepared with a carbon-based material as a carrier, and the main body of the catalyst is Ni, Al, Co, Ru, Any one or two of Rh, Pd or Pt.
The method for storing hydrogen using H-type hydrate according to claim 1, wherein in step (2), the volume ratio of the pure water added to the reaction kettle and the hydrogenation product when the hydrate is formed is 0.5-20.
The method for hydrogen storage using H-type hydrate according to claim 1, characterized in that, in step (2), the volume ratio of the pure water added to the reactor and the hydrogenation product when the hydrate is formed is 2.5-6.
The method for hydrogen storage using H-type hydrate according to claim 1, wherein the temperature required for the formation of the H-type hydrate is -50-20°C.
The method for hydrogen storage using H-type hydrate according to claim 1, characterized in that the pressure of methane introduced during the hydration reaction is 0.2-40.0 MPa.
The method for hydrogen storage using H-type hydrate according to any one of claims 1 to 8, characterized in that the pressure of the hydrogen introduced during the hydration reaction is 1.0-70.0 MPa.