CN112387117A

CN112387117A - Light-promoted carbon dioxide desorption reaction device and desorption method

Info

Publication number: CN112387117A
Application number: CN202011251836.0A
Authority: CN
Inventors: 朱英明
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2020-11-11
Filing date: 2020-11-11
Publication date: 2021-02-23

Abstract

The invention provides a device for desorbing carbon dioxide by light promotion and a method for desorbing the carbon dioxide, which comprises an absorption reactor and a desorption reactor; the absorption reactor and the desorption reactor are communicated through a pump; the absorption reactor is a darkroom, and absorption solution is arranged in the darkroom; the absorption reactor is also provided with a flue gas inlet pipe and a nitrogen gas outlet pipe, the lower end of the flue gas inlet pipe is positioned below the liquid level of the solution, and the lower end of the nitrogen gas outlet pipe is positioned above the liquid level of the solution; one side of the desorption reactor is provided with an illumination device, and the top of the desorption reactor is provided with a carbon dioxide exhaust pipe. The invention can realize the desorption of carbon dioxide at normal temperature, namely 20-50 ℃, and saves energy.

Description

Light-promoted carbon dioxide desorption reaction device and desorption method

Technical Field

The invention relates to the technical field of waste gas treatment, in particular to a light-promoted carbon dioxide desorption reaction device and a desorption method.

Background

Efficient and economic carbon capture is one of key technologies for realizing large-scale carbon dioxide emission reduction. A part of the emission of carbon dioxide in China comes from coal-fired power plants, and accounts for 37% of the total emission, and the capture of carbon dioxide after combustion is the most feasible technical means for solving the problem of carbon dioxide emission of the coal-fired power plants. Among them, the organic amine method for capturing carbon dioxide has large absorption capacity, high selectivity and low requirement on external devices, but the method has the main problem of high carbon dioxide desorption energy consumption which accounts for 70-80% of the total energy consumption in the capturing process. The energy consumption of carbon dioxide desorption comprises 1, desorbing reaction heat; 2. sensible heat required by heating of the absorption liquid; 3. latent heat required for solvent vaporization. Taking Monoethanolamine (MEA) as an example, two reaction processes of carbamate decomposition (1) and deprotonation (2) of protonated amine can not be carried out spontaneously at normal temperature, in order to ensure desorption rate and desorption rate, an organic amine aqueous solution needs to be desorbed at 100-140 ℃, a large amount of sensible heat and latent heat are consumed, and the method is the root cause of high energy consumption in carbon dioxide desorption by an organic amine method.

Disclosure of Invention

Aiming at the technical problems, the invention provides a light-promoted carbon dioxide desorption reaction device and a desorption method, which are used for realizing carbon dioxide desorption at the room temperature.

The specific technical scheme is as follows:

a device for light-promoted desorption of carbon dioxide, comprising an absorption reactor and a desorption reactor; the absorption reactor and the desorption reactor are communicated through a pump;

the absorption reactor is a darkroom, and absorption solution is arranged in the darkroom; the absorption reactor is also provided with a flue gas inlet pipe and a nitrogen gas outlet pipe, the lower end of the flue gas inlet pipe is positioned below the liquid level of the solution, and the lower end of the nitrogen gas outlet pipe is positioned above the liquid level of the solution;

one side of the desorption reactor is provided with an illumination device, and the top of the desorption reactor is provided with a carbon dioxide exhaust pipe.

The invention also provides a method for promoting carbon dioxide desorption by light, and the device for promoting carbon dioxide desorption by light comprises the following steps:

(1) introducing the flue gas into an absorption reactor for carbon dioxide absorption reaction;

(2) pumping the absorption solution into a desorption reactor for desorption after the absorption is finished;

(3) and pumping the desorbed absorption solution back to the absorption reactor for reabsorption reaction.

Wherein, the absorption solution is organic amine solution added with photoacid molecules and reversible photoacid.

Further, the organic amine solution is an MEA solution, and the mass fraction of the organic amine solution is 5-30%; the dosage of the photoacid molecule is 0.01-12% of the mass fraction of the absorption solution, and the reversible photoacid is merocyanin.

Preferably, the desorption condition is normal temperature, and light is irradiated by an illumination device.

The invention has the advantages that:

the invention can realize the desorption of carbon dioxide at normal temperature, namely 20-50 ℃, and saves energy.

Drawings

FIG. 1 is a schematic diagram of the apparatus of the present invention;

FIG. 2 is a UV-VIS absorption spectrum of an aqueous solution of 2-naphthol and merocyanin;

FIG. 3 is a graph showing the change in pH of the absorption solution before and after light irradiation.

Detailed Description

The following examples are described in detail.

As shown in fig. 1, the apparatus for photo-assisted desorption of carbon dioxide comprises an absorption reactor 1 and a desorption reactor 2; the absorption reactor 1 is communicated with the desorption reactor 2 through a pump 6;

the absorption reactor 1 is a darkroom and is internally provided with absorption solution; the absorption reactor 1 is also provided with a flue gas inlet pipe 3 and a nitrogen gas outlet pipe 4, the lower end of the flue gas inlet pipe 3 is positioned below the liquid level of the solution, and the lower end of the nitrogen gas outlet pipe 4 is positioned above the liquid level of the solution;

and one side of the desorption reactor 2 is provided with an illumination device 7, and the top of the desorption reactor is provided with a carbon dioxide exhaust pipe 5.

(1) introducing the flue gas into an absorption reactor 1 to perform carbon dioxide absorption reaction; the absorption solution is organic amine solution added with photoacid molecules and reversible photoacid. The organic amine solution is an MEA solution, and the mass fraction is 5-30%; the dosage of the photoacid molecule is 0.01-12% of the mass fraction of the absorption solution, and the reversible photoacid is merocyanin. The desorption condition is normal temperature, and light is emitted through the illumination device 7.

(2) After the absorption is finished, the absorption solution is pumped into the desorption reactor 2 by a pump 6 for desorption;

(3) the desorbed absorbing solution is returned to the absorption reactor 1 by the pump 6 to undergo the reabsorption reaction.

A photo acid molecule (mass fraction of 0.01% to 12%) and a reversible photo acid such as 2-naphthol (pKa 9.5, pKa 3.1) or merocyanin (pKa 7.8, pKa 3.2) are added to an organic amine solution (a solution such as MEA, mass fraction of 5% to 30%), and a carbon dioxide absorption reaction is performed in a dark room. After absorption, the absorption solution is pumped into the desorption reactor 2 for desorption under the condition of normal temperature (20-50 ℃), and light (such as Wie tungsten lamp, xenon lamp, LED, sunlight and the like) is emitted to the right side of the desorption reactor 2 to realize desorption of carbon dioxide. The desorbed solution is pumped into the absorption reactor 1 for reabsorption reaction.

Naphthol compounds such as 2-naphthol (pKa 9.5, pKa 3.1), merocyanin (pKa 7.8, pKa 3.2) and other reversible photoacid, which show significant transition absorption at wavelengths of 350nm and 515nm, respectively, as shown in fig. 2 and 3, indicating that protons are released at this wavelength of incident light. The pH decreased from 7.1 to 4.8 after 10min of light irradiation with 0.1 wt.% 2-naphthol solution; and 0.01 wt.% of meroanthocyanins was irradiated for 30s with light to decrease the pH from 6.7 to 4.5. The experiment of adjusting and controlling the pH of the rich solution by absorbing CO2 by MEA shows that when the pH of the solution is 4.5, the desorption rate can reach 85% +/-3% at room temperature.

Claims

1. The device for desorbing the carbon dioxide by light promotion is characterized by comprising an absorption reactor and a desorption reactor; the absorption reactor and the desorption reactor are communicated through a pump;

2. A method for photo-assisted desorption of carbon dioxide using the photo-assisted desorption apparatus of claim 1, comprising the steps of:

3. The method of claim 2, wherein the absorption solution is an organic amine solution with added photoacid molecules or reversible photoacid.

4. The method for photo-assisted desorption of carbon dioxide as claimed in claim 3 wherein the organic amine solution is an MEA solution with a mass fraction of 5-30%; the dosage of the photoacid molecule is 0.01-12% of the mass fraction of the absorption solution, and the reversible photoacid is merocyanin.

5. The method for photo-assisted desorption of carbon dioxide as claimed in claim 2, wherein the desorption conditions are normal temperature and light is irradiated by the light irradiation device.