CN115304027A

CN115304027A - Method for preparing hydrogen by laser total hydrolysis

Info

Publication number: CN115304027A
Application number: CN202211056603.4A
Authority: CN
Inventors: 杨国伟; 闫波; 曹玮玮
Original assignee: Sun Yat Sen University
Current assignee: Sun Yat Sen University
Priority date: 2022-08-31
Filing date: 2022-08-31
Publication date: 2022-11-08

Abstract

The invention belongs to the technical field of hydrogen production by full hydrolysis, and particularly relates to a method for producing hydrogen by laser full hydrolysis. The invention utilizes the pulse laser to focus in the liquid to generate the vacuole, and realizes the high-efficiency full decomposition of water through the microenvironment such as instantaneous high energy, high temperature and the like provided by the rapid quenching of the vacuole to generate the high added value products such as hydrogen, oxygen and the like. On one hand, the laser is utilized to generate a local high-temperature environment, which is beneficial to the rapid reaction and the rapid dissociation of water; on the other hand, cavitation bubbles generated by laser can quench rapidly, causing the product to be released rapidly and difficult to return to the initial state by reverse reaction. The method does not need a catalyst, is simple, clean and efficient, has high yield, and can be realized at room temperature. Compared with the classical photocatalysis, thermocatalysis and electrocatalysis methods, the method avoids harsh reaction conditions such as high temperature, high pressure and high current of the environment, and has important significance for developing new technologies of hydrogen production and oxygen production by full hydrolysis and the application of pulse laser in local high-temperature chemical synthesis.

Description

Method for preparing hydrogen by laser total hydrolysis

Technical Field

The invention belongs to the technical field of hydrogen production by full hydrolysis, and particularly relates to a laser full hydrolysis hydrogen production method.

Background

In recent years, the world has been faced with serious energy crisis and environmental challenges due to the increasing human activities. "carbon neutralization" is an important method to address this crisis. To achieve the goal of "carbon neutralization," fossil energy use is curtailed and new clean sustainable energy sources are sought. Hydrogen has received wide attention from people as a clean, environmentally friendly energy source with high mass energy density and high combustion heat value. The hydrogen source is wide, and the cleanest and efficient method is to prepare hydrogen and oxygen by water cracking. At present, the conventional full-hydrolytic methods mainly comprise thermal catalysis, photocatalysis, electrocatalysis and the like. However, the above methods have the disadvantages of complicated process, high energy consumption, low efficiency, etc. due to the large chemical reaction barrier and complicated reaction path required for the full water hydrolysis. In addition, the lack of an economically efficient catalyst also greatly hinders the application of full-scale hydrolysis. Therefore, there is a need to find a simple, mild, and green process for the full hydrolysis of water to produce hydrogen and oxygen.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a method for preparing hydrogen by fully hydrolyzing water with laser, which adopts pulse laser to generate vacuoles in water to realize the full hydrolysis of the water and generate hydrogen and oxygen.

In order to realize the purpose, the invention is realized by the following technical scheme:

the invention provides a method for preparing hydrogen by laser total hydrolysis, which is characterized in that high-temperature vacuoles are generated in water-containing liquid by laser, and the water is driven to be totally decomposed by rapid quenching of the high-temperature vacuoles to generate hydrogen.

Preferably, the laser is a pulsed laser.

Preferably, the aqueous liquid is pure water.

The invention utilizes the pulse laser to focus in the liquid such as water and the like and generates high-temperature vacuole, thereby leading the water to be quickly and completely decomposed and generating related products such as hydrogen, oxygen and the like. The pulse laser total water splitting method utilizes the thermodynamics and kinetics mechanism of high-temperature chemical reaction in the bubbles. Thermodynamically, the extremely high temperature induced in the liquid by the pulsed laser promotes efficient reaction and ensures high yield. From a kinetic point of view, the rapid quenching process of the bubble causes the primary products of the high temperature chemical reaction in the bubble to freeze, while the high energy barrier of the reverse reaction prevents the products from returning to the original state. Therefore, the synergy of thermodynamics and kinetics ensures high efficiency of pulsed laser full-hydrolysis. Therefore, the cavitation technology generated in the liquid by the pulse laser is expected to become a method for preparing hydrogen and oxygen by high-efficiency full-hydrolysis under a mild condition except catalytic chemistry.

Preferably, the action time of the laser is more than 40min.

Preferably, the yields of oxygen and hydrogen increase with increasing laser energy; at the same time, the yields of oxygen and hydrogen also increase with increasing laser frequency.

Preferably, the laser has an environment of room temperature.

Compared with the prior art, the invention has the beneficial effects that:

the invention discloses a method for preparing hydrogen by laser total hydrolysis, which utilizes pulse laser to generate vacuole in liquid to realize high-efficiency total hydrolysis of water and generate hydrogen and oxygen. On one hand, the laser is utilized to generate a local high-temperature environment, which is beneficial to the rapid reaction and the rapid dissociation of water; on the other hand, cavitation bubbles generated by laser can quench rapidly, causing the product to be released rapidly and difficult to return to the initial state by reverse reaction. The method does not need a catalyst, is simple, clean, efficient and high in yield, and can be realized at room temperature. Compared with the classical catalysis paths such as photocatalysis, thermocatalysis, electrocatalysis and the like, the method avoids harsh reaction conditions such as high temperature, high pressure, high current and the like of the environment, and has important significance for developing new technologies of hydrogen production and oxygen production by full hydrolysis and the application of pulse laser in local high-temperature chemical synthesis.

Drawings

FIG. 1 is a schematic diagram of a pulsed laser full-hydrolysis device;

FIG. 2 shows hydrogen gas yields at different laser pulse energies;

FIG. 3 shows the hydrogen yield for different laser pulse durations;

FIG. 4 shows the oxygen yield for different laser pulse durations;

FIG. 5 shows the hydrogen and oxygen yields at different laser pulse frequencies;

FIG. 6 is a schematic diagram of pulsed laser total hydrolysis (A is pulsed laser generating high temperature cavitation in water, B is cavitation rapid quenching generating instantaneous high energy and high temperature).

Detailed Description

The following further describes the embodiments of the present invention. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The experimental procedures in the following examples were carried out by conventional methods unless otherwise specified, and the test materials used in the following examples were commercially available by conventional methods unless otherwise specified.

Example 1 method for preparing hydrogen by laser total hydrolysis

The method focuses laser beams under the water surface through pulse laser, and forms high-temperature vacuoles at a focus, so that water is driven to be efficiently cracked into hydrogen and oxygen, a reaction container is a quartz reactor (shown in figure 1), and the specific process for preparing the hydrogen and the oxygen by efficiently decomposing the water comprises the following steps:

pouring ultrapure water into a quartz chamber reactor at room temperature, focusing a laser beam generated by a pulse energy and frequency adjustable pulse laser (manufacturer: spectra-physics, model: PRO-250-10E) below a water surface to enable the focal spot size of the laser beam to be about 1mm, forming high-temperature vacuole at the focal point, rapidly quenching the vacuole to provide instantaneous microenvironments of high energy, high temperature and the like to crack water to prepare hydrogen and oxygen, and changing the concentration of a product by adjusting the pulse energy, the frequency and the acting time of the laser.

First, the pulse energy (200-700 mJ/pulse) of the laser was varied under the conditions that the laser frequency was 10Hz and the action time was 20min, and the gas generated from the reaction apparatus was collected and detected by gas chromatography, and the results thereof are shown in FIG. 2, which indicates that the yields of oxygen and hydrogen increased as the laser energy increased. Therefore, the pulse laser is focused underwater to realize full water decomposition, and high-value-added products such as hydrogen, oxygen and the like can be generated efficiently and selectively.

Secondly, changing the action time (20-60 min) of the laser under the conditions that the laser energy is 400mJ and the frequency is 10Hz, collecting the gas generated by the reaction device by using a gas bag, and detecting the generated gas by using a gas chromatograph to verify the generation of oxygen and hydrogen. The results are shown in fig. 3 and 4, which show that the hydrogen and oxygen yields increase with increasing laser action. Because the laser is a pulse laser, water can be more efficiently cracked into hydrogen and oxygen when the action time of the pulse laser is increased.

Finally, changing the frequency (1-10 Hz) of the laser under the conditions that the laser energy is 400mJ and the acting time is 20min, collecting the gas generated by the reaction device by using a gas bag, and detecting the generated gas by using a gas chromatograph to verify that oxygen and hydrogen are generated. The results are shown in fig. 5, which shows that the hydrogen and oxygen yields increase with increasing laser frequency. Because the laser is a pulsed laser, water can be more efficiently split into hydrogen and oxygen as the frequency of the pulsed laser is increased.

The mechanism of the invention is that the pulsed laser is used to generate bubbles in the liquid water, and the temperature in the bubbles can reach 10 DEG ⁴ K, the bubble quenching rate can reach 10 ⁸ K/s. Thermodynamically, the ultra-high temperature environment inside the bubble can cause the water to be completely decomposed without any other catalyst; in terms of dynamics, the ultra-fast cooling rate enables hydrogen and oxygen generated by high-temperature reaction to be rapidly and sufficiently cooled to room temperature, and the reverse reaction of the hydrogen and the oxygen which react again at high temperature to generate water is prevented, so that the ultra-efficient hydrogen production efficiency by full water splitting is achieved. (as shown in fig. 6). Thus, the present invention utilizes a pulsed laser focused in a liquid to create a cavity in which to emptyThe method has the advantages of simple, clean, efficient and high-yield, and can realize high-efficiency complete decomposition of water in bubbles to generate high-value-added products such as hydrogen, oxygen and the like without catalysts. In conclusion, besides catalytic chemistry, the pulse laser can be used as a method for preparing hydrogen and oxygen by hydrolysis at normal temperature and normal pressure, and the method has the advantages of simplicity, cleanness, high yield and the like.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.

Claims

1. A method for preparing hydrogen by laser full-hydrolysis is characterized in that high-temperature vacuoles are generated in water-containing liquid through laser, and the water is driven to be fully decomposed by utilizing rapid quenching of the high-temperature vacuoles to generate hydrogen.

2. The method for preparing hydrogen through laser total hydrolysis according to claim 1, wherein the laser is a pulse laser.

3. The method for producing hydrogen by laser total hydrolysis as claimed in claim 1, wherein the aqueous liquid is pure water.

4. The method for preparing hydrogen through laser total hydrolysis as claimed in claim 1, wherein the action time of the laser is more than 40min.

5. The method for preparing hydrogen through laser total hydrolysis according to claim 1, wherein the working environment of the laser is room temperature.