Use of n-acyl amino acid surfactants in gas hydrate formation
By using N-acyl amino acid surfactants as gas hydrate generation promoters, the environmental pollution and foaming problems of traditional surfactants have been solved, achieving efficient, green, and economical gas hydrate generation and storage.
Patent Information
- Application Number
- CN202411372872.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2025-10-21
- Estimated Expiration
- 2044-09-29
AI Technical Summary
Traditional surfactants have problems with non-degradability and foam generation in the formation of gas hydrates, which leads to increased environmental pollution and difficulty in recycling processes, as well as low formation rate and gas storage efficiency.
An N-acyl amino acid surfactant, such as sodium cocoyl glycinate, was used as a hydrate formation promoter to prepare solid gas hydrates by forming a mixed solution in water and reacting it with a gas under specific conditions.
It improves the formation rate and storage capacity of gas hydrates, solves environmental pollution and foaming problems, reduces costs, simplifies operation procedures, and improves gas storage efficiency.
Smart Images
Figure CN119192019B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of hydrate formation promoters, and particularly relates to a method for using an N-acylamino acid type surfactant as a gas hydrate promoter and applying it in gas hydrate preparation. Background Art
[0002] In recent years, as environmental problems caused by traditional fossil fuels have become increasingly severe, green economy clean energy sources such as methane and hydrogen have attracted increasing attention. While gas fuels are greener and cleaner, their low energy density and the poor safety of traditional storage and transportation methods have prevented them from achieving large-scale application. Against this backdrop, hydrate gas solidification technology, a safer and more environmentally friendly method, has garnered widespread attention.
[0003] Gas hydrates are non-stoichiometric cage-like crystalline substances formed by water and small gas molecules such as methane, ethane, and hydrogen under suitable temperature and pressure conditions. The main water molecules are linked by hydrogen bonds to form polyhedral cages, which are filled with guest gas molecules, making them thermodynamically stable. Depending on the size of the guest molecules, each cubic meter of hydrate can store 160–180 cubic meters of gas. However, due to the extremely slow formation rate of gas hydrates in pure water systems and low gas storage efficiency, researchers have proposed a series of physical and chemical methods to enhance the reaction. The use of physical methods requires a large amount of energy, which is not conducive to the industrialization of hydrate gas solidification technology. Chemical methods, on the other hand, mainly rely on the addition of small amounts of accelerators to enhance the reaction, which can effectively reduce energy consumption, simplify the process, and thus reduce costs and improve economic benefits.
[0004] Surfactants have been reported as gas hydrate formation promoters. Their mechanism is adsorption on the solution surface. To stabilize the system, surfactant molecules, after dissolving in water, accumulate on the liquid surface. Furthermore, because surfactant molecules are organic compounds with weak intermolecular interactions, their accumulation on the liquid surface rapidly decreases with increasing concentration, further reducing the surface Gibbs function. This increases the solubility and diffusion coefficient of sparingly soluble gases in the liquid, enhancing gas-liquid contact at the molecular level and thus promoting the rapid initiation of gas hydrate formation. Furthermore, due to their excellent dispersibility, the addition of surfactants prevents gas hydrates from agglomerating on the liquid surface, isolating them from contact and preventing further reaction. Therefore, the addition of surfactants as kinetic promoters during gas hydrate formation can significantly increase the reaction rate and enhance the reaction's completeness, resulting in greater gas storage capacity and significantly improving gas hydrate formation efficiency. However, the use of conventional surfactants presents two critical challenges: environmental challenges posed by their non-degradability and the generation of large amounts of foam during gas hydrate decomposition and recovery, which complicates the recovery process. Summary of the Invention
[0005] In response to the problems existing in traditional surfactants when used as gas hydrate formation promoters, the present invention provides a new type of hydrate formation promoter and its application method, which is green, efficient, economical, safe and has good application prospects.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] One of the purposes of the present invention is to protect a class of hydrate formation promoters, which are specifically N-acylamino acid type surfactants, and their general structural formula is as follows:
[0008] ,
[0009] Wherein, R is selected from one of lauroyl, cocoyl, oleyl, etc.; R1 and R2 are independently selected from one of glutamic acid, glycine, alanine, and sarcosine.
[0010] The second purpose of the present invention is to protect the use of the hydrate in the preparation of gas hydrates, especially high gas storage density gas hydrates.
[0011] Furthermore, the application method is specifically to add the hydrate formation promoter into water to form a mixed solution, and then introduce gas to react, thereby obtaining solid gas hydrate.
[0012] Furthermore, the amount of the hydrate formation promoter added to water is 50 ppm to 5000 ppm.
[0013] Furthermore, the mixed solution can be frozen and crushed into particles for use.
[0014] Furthermore, the particle size of the particles is 0.1 mm to 1 mm.
[0015] Furthermore, the gas is a gas that is hardly soluble in water, such as methane, ethane, propane, ethylene, hydrogen, hydrogen sulfide, oxygen, nitrogen, argon, krypton, xenon, etc.
[0016] Furthermore, the reaction is carried out at a temperature of 268.15-288.15 K and a pressure of 0.5-15.0 MPa, and the reaction time is 0.5-12 h.
[0017] N-acyl amino acid surfactants are biodegradable and extremely mild. Unlike traditional surfactants, they do not produce large amounts of foam, making them particularly suitable for hydrate-solidified gas applications. Furthermore, N-acyl amino acid surfactants, such as sodium cocoyl glycinate and sodium lauroyl glycinate, are already commercially available, ensuring quality and affordability. Furthermore, when used as hydrate-forming promoters, the dosage required per reaction is extremely small, with the optimal dosage being only 500 parts per million (ppm), effectively controlling the cost of industrial applications.
[0018] The present invention has the following advantages and features:
[0019] (1) N-acylamino acid surfactants are mild, biodegradable, and economical anionic surfactants. While retaining the excellent properties of traditional surfactants, they can solve the environmental damage problems caused by the use of traditional surfactants and the foaming problem during recycling.
[0020] (2) The present invention uses N-acylamino acid surfactant as a gas hydrate formation promoter, which can greatly increase the gas hydrate formation rate and gas storage capacity, improve the gas storage efficiency, and provide a feasible solution for the industrialization of the storage and transportation method of hydrate-solidified gas.
[0021] (3) The method of using N-acylamino acid surfactant as a promoter to prepare high gas storage density hydrate is simple to operate, green and environmentally friendly, low cost and good economic effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 Schematic diagram of the transparent sapphire high-pressure reaction system used.
[0023] Figure 2Graph showing pressure changes during methane hydrate formation in Example and Comparative Example.
[0024] Figure 3 Graph showing changes in methane gas absorption per unit volume of hydrate in Examples and Comparative Examples.
[0025] Figure 4 The induction time and T 90 Comparison chart of the graph. DETAILED DESCRIPTION
[0026] The technical solutions and implementation effects of the present invention are further described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of implementation of the present invention.
[0027] In order to study the effect of N-acylamino acid surfactant as hydrate kinetic promoter on gas hydrate formation, sodium cocoyl glycinate was used as an example. Figure 1 The experiment was conducted in a transparent sapphire high-pressure reaction system with visualization. The system mainly consists of a high-pressure reactor, a balance reactor, a water bath, a temperature sensor, a pressure sensor data collection system, etc. The maximum working volume of the high-pressure reactor is 425 cm 3 , the maximum working pressure is 20 MPa and the working temperature range is -80-150 ℃.
[0028] Before the reaction begins, the entire experimental system is cleaned with deionized water and vacuum-dried. The prepared reagents are then placed in a high-pressure reactor, and the water bath temperature is set to the experimental temperature. After the system temperature stabilizes for 2 hours, pure methane gas is introduced into the reactor from the equilibrium vessel, displacing the air within the vessel 3-4 times. Experimental gas is then introduced at a pressure (less than the equilibrium pressure for hydrate formation at this temperature, calculated using the Chen-Guo hydrate model) to allow dissolution equilibrium. Experimental gas is then introduced from the equilibrium vessel to raise the system pressure to the test pressure. The inlet valve is closed and the reaction is initiated. The reaction is considered complete when the reaction pressure remains constant for 2 hours.
[0029] Example 1
[0030] The reaction system consisted of a mixed solution of 0.004 g of sodium cocoyl glycinate and 39.996 g of deionized water, with a mass fraction of 100 ppm. This mixed solution was fed into a reactor with pure methane as the experimental gas, at a pressure of 6.0 MPa and a temperature of 275.15 K.
[0031] The results showed that hydrates were formed rapidly during the entire experimental process, indicating that the hydrate promoter had a good effect in promoting hydrate formation.
[0032] Example 2
[0033] The reaction system consisted of a mixed solution of 0.02 g of sodium cocoyl glycinate and 39.98 g of deionized water, with a mass fraction of 500 ppm. This mixed solution was fed into a reactor with pure methane as the experimental gas, at a pressure of 6.0 MPa and a temperature of 275.15 K.
[0034] The results showed that hydrates were formed rapidly during the entire experimental process, indicating that the hydrate promoter had a good effect in promoting hydrate formation.
[0035] Example 3
[0036] The reaction system consisted of a mixed solution of 0.04 g of sodium cocoyl glycinate and 39.96 g of deionized water, with a mass fraction of 1000 ppm. This mixed solution was fed into a reactor with pure methane as the experimental gas at a pressure of 6.0 MPa and a temperature of 275.15 K.
[0037] The results showed that hydrates were formed rapidly during the entire experimental process, indicating that the hydrate promoter had a good effect in promoting hydrate formation.
[0038] Example 4
[0039] The reaction system consisted of a mixture of 0.004 g of sodium cocoyl glycinate and 39.996 g of deionized water, with a mass fraction of 100 ppm. The resulting mixture was frozen at -20°C and pulverized into frozen pellets with a particle size of 0.1 mm to 1 mm. The frozen pellets were then fed into a reactor, where pure methane was introduced at a pressure of 6.0 MPa and a temperature of 272.15 K.
[0040] The results showed that hydrates were formed rapidly during the entire experimental process, indicating that the hydrate promoter had a good effect in promoting hydrate formation.
[0041] Example 5
[0042] The reaction system consisted of a mixed solution of 0.02 g of sodium cocoyl glycinate and 39.98 g of deionized water, with a mass fraction of 500 ppm. The resulting mixed solution was frozen at -20°C and crushed into frozen pellets with a particle size of 0.1 mm to 1 mm. The frozen pellets were then fed into a reactor, where pure methane was introduced as the experimental gas at a pressure of 6.0 MPa and a temperature of 272.15 K.
[0043] The results showed that hydrates were formed rapidly during the entire experimental process, indicating that the hydrate promoter had a good effect in promoting hydrate formation.
[0044] Example 6
[0045] The reaction system consisted of a mixture of 0.04 g of sodium cocoyl glycinate and 39.96 g of deionized water, with a mass fraction of 1000 ppm. The resulting mixture was frozen at -20°C and crushed into frozen pellets with a particle size of 0.1 mm to 1 mm. The frozen pellets were then fed into a reactor, where pure methane was introduced at a pressure of 6.0 MPa and a temperature of 272.15 K.
[0046] The results showed that hydrates were formed rapidly during the entire experimental process, indicating that the hydrate promoter had a good effect in promoting hydrate formation.
[0047] Comparative Example 1
[0048] The reaction system was 40 g of deionized water. The solution was fed into the reactor. The experimental gas introduced was pure methane. The experimental pressure was 6.0 MPa and the experimental temperature was 275.15 K.
[0049] The results showed that hydrate formation was slow throughout the experiment.
[0050] Comparative Example 2
[0051] The reaction system consisted of a mixed solution of 0.02 g of glycine and 39.96 g of deionized water, with a mass fraction of 500 ppm of glycine. This mixed solution was fed into a reactor with pure methane as the experimental gas. The experimental pressure was 6.0 MPa and the experimental temperature was 275.15 K.
[0052] The results show that during the entire experiment, the hydrate formation rate was slow and the gas storage capacity was low.
[0053] Comparative Example 3
[0054] The reaction system consisted of a mixed solution of 0.02 g of sodium lauryl sulfate (SLS) and 39.96 g of deionized water, with a mass fraction of 500 ppm. This mixed solution was fed into a reactor with pure methane as the experimental gas. The experimental pressure was 6.0 MPa and the experimental temperature was 275.15 K.
[0055] The results showed that hydrates formed rapidly throughout the experiment, but the gas storage capacity was low.
[0056] Table 1 shows the induction time of the examples and comparative examples. T 90(the time required for the gas storage volume to reach 90% of the final gas storage volume) and the final gas storage volume.
[0057] Table 1 Summary of results
[0058]
[0059] As can be seen from Table 1, the use of N-acylamino acid surfactant as a gas hydrate formation promoter can greatly increase the gas hydrate formation rate and gas storage capacity, thereby improving the gas storage efficiency.
[0060] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.
Claims
1. A method for preparing gas hydrates using an N-acylamino acid surfactant as a hydrate formation promoter, characterized in that: An N-acylamino acid surfactant is added to water as a hydrate formation promoter to form a mixed solution, and then a gas is introduced to react, thereby obtaining a solid gas hydrate; The N-acyl amino acid surfactant is sodium cocoyl glycinate; The gas is methane.
2. The method according to claim 1, wherein The amount of the N-acylamino acid surfactant added to water is 50 ppm to 5000 ppm.
3. The method according to claim 1, characterized in that The mixed solution was frozen and pulverized into particles for use.
4. The method according to claim 3, characterized in that The particle size of the particles is 0.1 mm to 1 mm.
5. The method according to claim 1, wherein The reaction is carried out at a temperature of 268.15-288.15 K and a pressure of 0.5-15.0 MPa for a time of 0.5-12 h.