A biochar-based catalyst, a method for preparing the same and a method for desorption of an organic amine-rich liquid

Abstract

The present application belongs to the field of catalysts, and particularly relates to a biochar-based catalyst, a preparation method thereof and a desorption method of organic amine rich solution. The biochar-based catalyst is prepared from shell biochar through impregnation and anaerobic pyrolysis; the shell biochar is prepared from shell through crushing and carbonization; the shell is at least two of coconut shell, apricot shell, walnut shell and peanut shell; the impregnation liquid contains an aluminum source compound and potassium hydroxide. The biochar-based catalyst is simple to prepare, has excellent catalytic performance, good cycle stability, little influence on the performance of organic amine in absorbing CO2, long service life, is easy to recycle and reuse, low in cost and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalysts, and particularly relates to a biochar-based catalyst, a preparation method thereof and a desorption method of an organic amine rich solution. BACKGROUND

[0002] There are mainly three ways of CO2 capture: pre-combustion capture, in-combustion capture and post-combustion capture. Among them, the post-combustion capture technology is more mature, and is the most widely used carbon capture method on an industrial scale. The post-combustion carbon capture technology refers to separating and enriching CO2 from flue gas discharged from an industrial coal-fired power plant, and mainly includes absorption separation method, adsorption separation method and membrane separation method, etc. Organic amines, ionic liquids and ammonia water, etc. are often used as chemical absorbents of the absorption separation method, among which the organic amine method becomes the most mature carbon capture technology and is the only one that has realized commercial application, due to the advantages of high absorption rate, large absorption capacity, simple process flow, low cost, no pollution, etc.

[0003] Primary amines and secondary amines have a relatively fast CO2 absorption rate, and the bicarbonate formed by the reaction of tertiary amines with CO2 is conducive to reducing the desorption energy consumption, so a mixed organic amine combining primary amines or secondary amines with tertiary amines is often used as a carbon capture absorbent in industry. The desorption temperature of the conventional organic amine absorbent is usually 120-140℃, and the regeneration energy consumption is too high due to the sensible heat and latent heat of vaporization of water in the absorbent, and the energy consumption accounts for about 60% of the entire CO2 capture process cost.

[0004] Studies have shown that adding a proper catalyst can make the CO2-rich amine solution desorb CO2 at a lower temperature, promote the regeneration of the rich amine solution, save the energy consumption required in the CO2 desorption process, and minimize the corrosion of equipment and the degradation of amine solution. At present, the catalysts commonly used to promote the regeneration of the organic amine rich solution mainly include carbonic anhydrase, molecular sieves, solid superacids and metal oxides, etc. However, most of the catalysts have problems such as poor thermal stability, complex preparation process, high cost of raw materials, low catalytic performance, great influence on the CO2 absorption performance of organic amines, difficulty in recycling and utilization, short service life, etc. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a biochar-based catalyst, a preparation method thereof and a desorption method of an organic amine rich solution. The biochar-based catalyst provided by the present application has the advantages of simple preparation, excellent catalytic performance, good cycle stability, little influence on the CO2 absorption performance of organic amines, long service life, easy recycling and reuse, low cost and environmental friendliness.

[0006] The present application provides a biochar-based catalyst prepared from shell biochar through impregnation and anaerobic pyrolysis.

[0007] The shell biochar is made of shell after crushing and carbonization; the shell is at least two of coconut shell, apricot shell, walnut shell and peanut shell.

[0008] The impregnation solution contains aluminum source compound and potassium hydroxide.

[0009] Preferably, the shell is coconut shell and peanut shell; the mass ratio of the coconut shell and the peanut shell is 1:(0.5-2).

[0010] Preferably, the concentration of the aluminum source compound in the impregnation solution is 1-20wt%; the concentration of the potassium hydroxide in the impregnation solution is 1-20wt%; the use amount ratio of the shell biochar to the impregnation solution is 1g:(2-5)mL.

[0011] Preferably, the specific surface area of the biochar-based catalyst is 900-1300m 2 / g; the pore size of the biochar-based catalyst is 2-40nm; the total pore volume of the biochar-based catalyst is 0.4-1.3cm 3 / g.

[0012] The application provides a preparation method of the biochar-based catalyst.

[0013] a) crushing and carbonizing shell to obtain shell biochar; the shell is at least two of coconut shell, apricot shell, walnut shell and peanut shell;

[0014] b) impregnating the shell biochar in an impregnation solution containing aluminum source compound and potassium hydroxide to obtain an impregnation mixture;

[0015] c) performing anaerobic pyrolysis on the impregnation mixture to obtain a biochar-based catalyst.

[0016] Preferably, in step a), the carbonization temperature is 300-700℃; the carbonization time is 0.5-2h.

[0017] Preferably, in step c), the anaerobic pyrolysis temperature is 300-650℃; the anaerobic pyrolysis time is 0.5-3h.

[0018] The application provides a desorption method of organic amine rich solution, comprising the following steps:

[0019] The organic amine rich solution is heated and desorbed in the presence of a catalyst to obtain organic amine lean solution and gaseous CO2;

[0020] The catalyst is the biochar-based catalyst in the above technical solution or the biochar-based catalyst prepared by the preparation method in the above technical solution.

[0021] The organic amine rich solution is a product of the absorption of CO2 by the organic amine solution.

[0022] Preferably, the organic amine in the organic amine solution is one or more of ethanolamine, N-methyldiethanolamine, piperazine, 3-diethylaminopropylamine, diethylaminoethanol, diethylenetriamine, N,N-dimethylacetamide, triethylenetetramine and 2-amino-2-methyl-1-propanol.

[0023] Preferably, the organic amine in the organic amine solution is N-methyldiethanolamine and piperazine.

[0024] Compared with the prior art, the present application provides a biochar-based catalyst, a preparation method thereof and a desorption method of organic amine rich solution. The biochar-based catalyst provided by the present application is prepared from shell biochar through impregnation and anaerobic pyrolysis; the shell biochar is prepared from shell through crushing and carbonization; the shell is at least two of coconut shell, apricot shell, walnut shell and peanut shell; the impregnation solution used in the impregnation contains an aluminum source compound and potassium hydroxide. In the present application, the compounded shell biochar is used as raw material, and the compounded shell biochar is modified into a rich mesoporous structure and the aluminum oxide is loaded on the surface of the compounded shell biochar through potassium hydroxide modification and aluminum source loading and anaerobic pyrolysis. The mesoporous biochar surface has rich hydroxyl and carboxyl groups, which can provide the protons (H + ) required for the rich solution desorption reaction as an excellent proton acid, and the aluminum oxide loaded thereon acts as an amphoteric oxide, which can not only provide the basic sites required for the deprotonation reaction of the protonated amine (i.e. the transfer of H + from the protonated amine to water to form H3O + ), but also provide the acid sites to promote the desorption reaction. In addition, the moderate pore size of the mesoporous biochar can enable the desorption reaction substances and products to rapidly migrate in the pore channel, promote the mass transfer process and facilitate the desorption reaction. The catalyst provided by the present application simultaneously has proton acid, basic sites, Lewis acid sites and mesoporous structure, and can synergistically catalyze the desorption of the organic amine rich solution, effectively reduce the temperature of the amine solution regeneration, thereby reducing the energy consumption of the desorption, and the catalyst is simple to prepare, has good stability, is easy to recycle and utilize, has low cost and is environmentally friendly, and is particularly suitable for the desorption and regeneration of the mixed amine rich solution mainly containing N-methyldiethanolamine (MDEA). BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the provided drawings.

[0026] Figure 1It is the schematic view of the organic amine rich solution desorption test table provided by the embodiment of the present application.

[0027] In the drawing, 1 is an oil bath pot, 2 is a thermometer, 3 is a sampling port, 4 is an A rotor, 5 is a catalyst, 6 is a condenser water outlet, 7 is a condenser water inlet, and 8 is a three-necked round-bottom flask. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0029] The present application provides a kind of biochar-based catalyst, is made by shell biochar through impregnation and anaerobic pyrolysis.

[0030] In the biochar-based catalyst provided by the application, the shell biochar is made from shell after crushing and carbonization; the shell is at least two of coconut shell, apricot shell, walnut shell and peanut shell, preferably coconut shell and peanut shell; the mass ratio of the coconut shell and peanut shell is preferably 1:(0.5-2), and can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2; the shell is preferably dried before being crushed; the drying method is preferably drying; the drying temperature is preferably 50-80°C, and can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; the drying time is preferably 4-6h, and can be 4h, 4.2h, 4.5h, 4.7h, 5h, 5.2h, 5.5h, 5.7h or 6h; the shell is preferably sieved after being crushed, and the sieve size is preferably 20-100 mesh, and can be 20 mesh, 30 mesh, 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh or 100 mesh; the carbonization is preferably carried out in an inert gas atmosphere; the inert gas is preferably one or more of argon (Ar), nitrogen (N2) and carbon dioxide (CO2); the gas flow rate of the inert gas is preferably 0.1-0.3L / min, and can be 0.1L / min, 0.15L / min, 0.2L / min, 0.25L / min or 0.3L / min; the carbonization temperature is preferably 300-700°C, and can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C or 700°C; the carbonization time is preferably 0.5-2h, and can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h.

[0031] In the biochar-based catalyst provided by the application, the impregnation solution used for impregnation contains an aluminum source compound and potassium hydroxide; the aluminum source compound is preferably one or more of AlCl3, Al(NO3)3, Al2(SO4)3, and NaAlO2; the concentration of the aluminum source compound in the impregnation solution is preferably 1-20 wt%, and can be specifically 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt%; the concentration of potassium hydroxide in the impregnation solution is preferably 1-20 wt%, and can be specifically 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, or 20 wt%; the use amount ratio of the nutshell biochar to the impregnation solution is preferably 1 g:(2-5) mL, and can be specifically 1 g:2 mL, 1 g:2.5 mL, 1 g:3 mL, 1 g:3.5 mL, 1 g:4 mL, 1 g:4.5 mL, or 1 g:5 mL; the impregnation mode is preferably ultrasonic impregnation; the impregnation temperature is preferably 10-40°C, and can be specifically 10°C, 15°C, 20°C, 25°C (room temperature), 30°C, 35°C, or 40°C; and the impregnation time is preferably 0.5-2 h, and can be specifically 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, or 2 h.

[0032] In the biochar-based catalyst provided by the application, the impregnant is preferably dried to a solvent-free state before the anaerobic pyrolysis; the drying method is preferably vacuum drying box drying; the drying temperature is preferably 60-80℃, and can be specifically 60℃, 65℃, 70℃, 75℃ or 80℃; the drying time is preferably 6-8h, and can be specifically 6h, 6.2h, 6.5h, 6.7h, 7h, 7.2h, 7.5h, 7.7h or 8h; the anaerobic pyrolysis is preferably carried out in an inert gas atmosphere; the inert gas is preferably one or more of argon (Ar), nitrogen (N2) and carbon dioxide (CO2); the gas flow rate of the inert gas is preferably 0.1-0.3L / min, and can be specifically 0.1L / min, 0.15L / min, 0.2L / min, 0.25L / min or 0.3L / min; the temperature of the anaerobic pyrolysis is preferably 300-650℃, and can be specifically 300℃, 320℃, 350℃, 370℃, 400℃, 420℃, 450℃, 470℃, 500℃, 520℃, 550℃, 570℃, 600℃, 620℃ or 650℃; the time of the anaerobic pyrolysis is preferably 0.5-3h, and can be specifically 0.5h, 0.7h, 1h, 1.2h, 1.5h, 1.7h, 2h, 2.3h, 2.5h, 2.7h or 3h.

[0033] In the biochar-based catalyst provided by the application, after the anaerobic pyrolysis is completed, the obtained product is preferably washed and dried.

[0034] In the biochar-based catalyst provided by the application, the specific surface area of the biochar-based catalyst is preferably 900-1300m 2 / g; the pore size of the biochar-based catalyst is preferably 2-40nm; and the total pore volume of the biochar-based catalyst is preferably 0.4-1.3cm 3 / g.

[0035] In the biochar-based catalyst provided by the application, the biochar-based catalyst is loaded with the pyrolysis product of an aluminum source compound on the surface; the pyrolysis product of the aluminum source compound is preferably AlOOH (flaky) and / or Al2O3 (granular); the thickness of the AlOOH is preferably 20-50nm; the size of the AlOOH is preferably 200-500nm; and the particle size of the Al2O3 is preferably 0.5-3nm.

[0036] The application also provides a preparation method of the biochar-based catalyst described in the above technical solution, which comprises the following steps:

[0037] a) crushing and carbonizing the fruit shell to obtain a fruit shell biochar;

[0038] b) impregnating the nutshell biochar in an impregnation solution containing an aluminum source compound and potassium hydroxide to obtain an impregnation mixture;

[0039] c) subjecting the impregnation mixture to anaerobic pyrolysis to obtain a biochar-based catalyst.

[0040] In the preparation method provided by the present application, in step a), the nutshell is at least two of coconut shell, apricot shell, walnut shell and peanut shell, preferably coconut shell and peanut shell; the mass ratio of the coconut shell and peanut shell is preferably 1:(0.5-2), and can be specifically 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.

[0041] In the preparation method provided by the present application, in step a), before the nutshell is crushed, it is preferably dried first; the drying method is preferably vacuum drying box drying; the drying temperature is preferably 50-80°C, and can be specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; the drying time is preferably 4-6h, and can be specifically 4h, 4.2h, 4.5h, 4.7h, 5h, 5.2h, 5.5h, 5.7h or 6h.

[0042] In the preparation method provided by the present application, in step a), before the nutshell is dried, it is preferably cleaned first.

[0043] In the preparation method provided by the present application, in step a), after the nutshell is crushed, it is preferably sieved, and the sieve hole of the sieving is preferably 20-100 mesh, and can be specifically 20 mesh, 30 mesh, 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh or 100 mesh.

[0044] In the preparation method provided by the present application, in step a), the carbonization is preferably carried out in an inert gas atmosphere; the inert gas is preferably one or more of argon (Ar), nitrogen (N2) and carbon dioxide (CO2); the gas flow rate of the inert gas is preferably 0.1-0.3L / min, and can be specifically 0.1L / min, 0.15L / min, 0.2L / min, 0.25L / min or 0.3L / min.

[0045] In the preparation method provided by the application, in step a), the temperature of carbonization is preferably 300-700℃, and can be specifically 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃ or 700℃; the time of carbonization is preferably 0.5-2h, and can be specifically 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h.

[0046] In the preparation method provided by the application, in step b), the aluminum source compound is preferably one or more of AlCl3, Al(NO3)3, Al2(SO4)3 and NaAlO2; the concentration of the aluminum source compound in the impregnation solution is preferably 1-20wt%, and can be specifically 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%.

[0047] In the preparation method provided by the application, in step b), the concentration of potassium hydroxide in the impregnation solution is preferably 1-20wt%, and can be specifically 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt% or 20wt%.

[0048] In the preparation method provided by the application, in step b), the ratio of the use amount of the nutshell biochar to the impregnation solution is preferably 1g:(2-5)mL, and can be specifically 1g:2mL, 1g:2.5mL, 1g:3mL, 1g:3.5mL, 1g:4mL, 1g:4.5mL or 1g:5mL.

[0049] In the preparation method provided by the application, in step b), the impregnation mode is preferably ultrasonic impregnation; the temperature of impregnation is preferably 10-40℃, and can be specifically 10℃, 15℃, 20℃, 25℃ (room temperature), 30℃, 35℃ or 40℃; the time of impregnation is preferably 0.5-2h, and can be specifically 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h.

[0050] In the preparation method provided by the application, in step c), before the anaerobic pyrolysis, the impregnation mixture is preferably dried to a solvent-free state; the drying method is preferably vacuum drying box drying; the drying temperature is preferably 60-80℃, and can be specifically 60℃, 65℃, 70℃, 75℃ or 80℃; the drying time is preferably 6-8h, and can be specifically 6h, 6.2h, 6.5h, 6.7h, 7h, 7.2h, 7.5h, 7.7h or 8h.

[0051] In the preparation method provided by the application, in step c), the anaerobic pyrolysis is preferably carried out in an inert gas atmosphere; the inert gas is preferably one or more of argon (Ar), nitrogen (N2) and carbon dioxide (CO2); the gas flow rate of the inert gas is preferably 0.1-0.3L / min, and can be specifically 0.1L / min, 0.15L / min, 0.2L / min, 0.25L / min or 0.3L / min.

[0052] In the preparation method provided by the application, in step c), the temperature of the anaerobic pyrolysis is preferably 300-650℃, and can be specifically 300℃, 320℃, 350℃, 370℃, 400℃, 420℃, 450℃, 470℃, 500℃, 520℃, 550℃, 570℃, 600℃, 620℃ or 650℃; the time of the anaerobic pyrolysis is preferably 0.5-3h, and can be specifically 0.5h, 0.7h, 1h, 1.2h, 1.5h, 1.7h, 2h, 2.3h, 2.5h, 2.7h or 3h.

[0053] In the preparation method provided by the application, in step c), preferably further comprising: after the anaerobic pyrolysis, the obtained product is washed and dried.

[0054] The application further provides a desorption method of an organic amine-rich solution, comprising the following steps:

[0055] The organic amine-rich solution is heated and desorbed in the presence of a catalyst to obtain an organic amine-lean solution and gaseous CO2;

[0056] The catalyst is the biochar-based catalyst described in the above technical solution or the biochar-based catalyst prepared by the preparation method described in the above technical solution.

[0057] The organic amine-rich solution is the product after the absorption of CO2 by an organic amine solution.

[0058] In the desorption method provided by the application, the organic amine in the organic amine solution is preferably one or more of ethanolamine (MEA), N-methyldiethanolamine (MDEA), piperazine (PZ), 3-diethylaminopropylamine (DEAPA), diethylaminoethanol (DEEA), diethylene triamine (DETA), N,N-dimethylacetamide (DMAC), triethylene tetramine (TETA) and 2-amino-2-methyl-1-propanol (AMP), and more preferably N-methyldiethanolamine (MDEA) and piperazine (PZ); the concentration of the N-methyldiethanolamine in the organic amine solution is preferably 5-30 wt%, and can be 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt% or 30 wt% in particular; the concentration of the piperazine in the organic amine solution is preferably 5-30 wt%, and can be 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt% or 30 wt% in particular.

[0059] In the desorption method provided by the application, the amount of the catalyst is 0.5-2 wt% of the mass of the organic amine rich solution, and can be 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2 wt% in particular.

[0060] In the desorption method provided by the application, the temperature of the heating desorption is preferably 75-95℃, and can be 75℃, 77℃, 80℃, 82℃, 85℃, 87℃, 90℃, 92℃ or 95℃ in particular.

[0061] The application uses compounded shell biochar as raw material, modifies it by potassium hydroxide, loads aluminum source and pyrolyzes in anaerobic environment, modifies the compounded shell biochar into rich mesoporous structure, and loads aluminum oxide on the surface of the biochar; the mesoporous biochar surface has rich hydroxyl and carboxyl groups, can provide the required protons (H + ) for the rich solution desorption reaction as excellent protonic acid, and the aluminum oxide loaded thereon is amphoteric oxide, which can not only provide the required basic sites (i.e. H + ) for the deprotonation reaction of the protonated amine, but also can provide the required proton (H +), and can also provide acidic sites to promote desorption reaction; in addition, the moderate pore size of the mesoporous biochar can enable the desorption reactants and products to rapidly migrate within the pores, promoting the mass transfer process and facilitating the desorption reaction. The catalyst provided by the present application simultaneously has protonic acid, basic sites, Lewis acid sites and mesoporous structure, and can synergistically catalyze the desorption of amine-rich liquid, effectively reducing the temperature of amine liquid regeneration, thereby reducing the energy consumption of desorption. In addition, the catalyst is simple to prepare, has good stability, is easy to recycle and use, has low cost and is environmentally friendly, and is particularly suitable for the desorption and regeneration of mixed amine rich liquid mainly containing MDEA.

[0062] For a clearer understanding, the following examples are described in detail below.

[0063] Example 1

[0064] (1) Washing and drying: 50 g of coconut shells and 50 g of peanut shells were washed and placed in a 70℃ oven for 5 h;

[0065] (2) Grinding and carbonization: the dried coconut shells and peanut shells were mixed, ground and passed through a 100 mesh sieve, then loaded into a corundum boat and placed in a muffle furnace, and carbonized at 600℃ for 2 h; N2 was introduced during the carbonization process, and the N2 flow rate was 0.2 L / min;

[0066] (3) Impregnation and loading: 5 g of the shell biochar obtained after carbonization was dispersed in 20 mL of an aqueous solution containing 10 wt% AlCl3 and 10 wt% potassium hydroxide, and ultrasonic immersion was performed for 1 h;

[0067] (4) Anaerobic pyrolysis: the mixed solution of step (3) was dried at 80℃ to remove water, and then pyrolyzed at 300℃ in a muffle furnace for 2 h; N2 was introduced during the pyrolysis process, and the N2 flow rate was 0.2 L / min;

[0068] (5) Washing and drying: the pyrolyzed material was washed with pure water until it was neutral, and then dried to obtain a biochar-based catalyst, denoted as AlOOH-MAC ① (mesoporous biochar loaded with aluminum oxyhydroxide).

[0069] The AlOOH-MAC ① prepared in this example has a specific surface area of about 1024.8 m 2 / g, a pore size of about 27 nm, and a total pore volume of about 0.83 cm 3 / g; the thickness of AlOOH is about 40 nm, and the size is 300-400 nm.

[0070] Comparative Example 1

[0071] The preparation process of Comparative Example 1 is referred to, except that 50 g of coconut shell and 50 g of peanut shell are replaced by 100 g of coconut shell, and the prepared biochar-based catalyst is recorded as AlOOH-MAC ② .

[0072] The AlOOH-MAC prepared in Comparative Example 1 ② has a specific surface area of about 986.8 m 2 / g, a pore size of about 26 nm, and a total pore volume of about 0.76 cm 3 / g; the thickness of AlOOH is about 40 nm, and the size is 300-400 nm.

[0073] Comparative Example 2

[0074] The preparation process of Comparative Example 1 is referred to, except that 50 g of coconut shell and 50 g of peanut shell are replaced by 100 g of peanut shell, and the prepared biochar-based catalyst is recorded as AlOOH-MAC ③ .

[0075] The AlOOH-MAC prepared in Comparative Example 1 ③ has a specific surface area of about 786.5 m 2 / g, a pore size of about 24 nm, and a total pore volume of about 0.57 cm 3 / g; the thickness of AlOOH is about 40 nm, and the size is 300-400 nm.

[0076] Example 2

[0077] (1) Washing and drying: 50 g of coconut shell and 50 g of peanut shell are weighed and washed and placed in a 70°C oven for 5 h;

[0078] (2) Grinding and carbonization: the dried coconut shell and peanut shell are mixed, ground, and passed through a 100-mesh sieve, then loaded into a corundum boat and placed in a muffle furnace for carbonization at 300°C for 2 h; N2 is introduced during the carbonization process at a flow rate of 0.2 L / min;

[0079] (3) Impregnation and loading: 5 g of the husk biochar obtained after carbonization is dispersed in 20 mL of an aqueous solution containing 20 wt% AlCl3 and 20 wt% potassium hydroxide, and ultrasonic impregnation is performed for 1 h;

[0080] (4) Anaerobic pyrolysis: the mixed solution of step (3) is dried at 80°C to remove water, then placed in a muffle furnace for pyrolysis at 650°C for 3 h; N2 is introduced during the pyrolysis process at a flow rate of 0.3 L / min;

[0081] (5) Washing and drying: the pyrolyzed material is washed with pure water until neutral, then dried, to obtain a biochar-based catalyst, recorded as Al2O3-MAC (mesoporous biochar loaded with alumina).

[0082] The Al2O3-MAC prepared in this embodiment has a specific surface area of ​​approximately 1114.2 m². 2 / g, pore size approximately 29nm, total pore volume approximately 0.89cm³. 3 / g; The particle size of Al2O3 is approximately 1.34nm.

[0083] Example 3

[0084] Catalytic desorption experiment of organic amine-rich solution

[0085] exist Figure 1 An intermittent catalytic desorption experiment of organic amine-rich solution was conducted on the experimental platform shown. The specific process was as follows: when the temperature of the oil bath reached 85℃, a 1L three-necked round-bottom flask containing 600g of organic amine-rich solution saturated with CO2 and a certain amount of catalyst was placed into the oil bath. The rotation speed of the oil bath was adjusted to 10r / min, and the desorption reaction was started. The amount of CO2 desorbed in the experiment was recorded by a gas chromatograph, and the desorption energy consumption was calculated. The desorption energy consumption (kJ / mol) refers to the energy required to desorb 1 mol of CO2.

[0086] Table 1 shows the energy consumption of desorption of rich solutions under different organic amine-rich solutions and catalyst conditions:

[0087] Table 1 Comparison of desorption energy consumption for different rich solutions

[0088]

[0089]

[0090] In Table 1, the amount of catalyst added is the mass percentage of the catalyst to the organic amine-rich solution; AlOOH and HZSM-5 are both commercially available, manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd.; the mesoporous biochar synthesis process is the same as the method in Example 1 above, except that AlCl3·6H2O and potassium hydroxide are not added in step (3); AlOOH-MAC ① The catalyst prepared in Example 1; AlOOH-MAC ② The catalyst prepared in Comparative Example 1; AlOOH-MAC ③ The catalyst prepared in Comparative Example 2 is shown; Al2O3-MAC is shown in Example 2.

[0091] Table 1 shows that the desorption energy consumption of mixed amine solutions is reduced compared to traditional amine liquid MEA; the addition of different catalysts can reduce the desorption energy consumption of organic amine-rich solutions; Example catalyst (AlOOH-MAC) ①, Al2O3-MAC) has better desorption promoting effect on mixed amine solution PZ+MDEA than other amine solutions; the desorption promoting effect of the catalyst (AlOOH-MAC ① ) of the example on the mixed amine solution is better than that of the catalyst (AlOOH-MAC ② , AlOOH-MAC ③ ) of the comparative example, which shows that the catalytic performance of the catalyst prepared by compounding multiple shells is better than that of a single shell.

[0092] Example 4

[0093] CO2 absorption experiment of lean organic amine solution

[0094] 500 g of the lean organic amine solution after the desorption experiment of Example 3 was placed in a constant temperature oil bath with a stirring speed of 10 r / min and an oil bath temperature of 40℃, and 200 mL / min of CO2 with a concentration of 99.995% was introduced into the oil bath until the solution was saturated with CO2. The CO2 content in the solution was titrated with dilute sulfuric acid, so as to compare the effects of the catalysts on the CO2 absorption performance of the amine solution.

[0095] The absorption performance of the lean solution under different organic amine lean solutions and catalyst working conditions is shown in Table 2.

[0096] Table 2: Comparison of absorption performance of different lean solutions

[0097]

[0098]

[0099] As can be seen from the above table, compared with no catalyst, the addition of the catalyst has little effect on the CO2 absorption performance of the lean solution, and the addition of the catalyst (AlOOH-MAC ① , Al2O3-MAC) of the example has almost no effect on the CO2 absorption performance of the lean solution.

[0100] Example 5

[0101] Cyclic stability experiment

[0102] According to the experimental conditions of Example 3 and Example 4, the organic amine solution was subjected to absorption and desorption experiments for 6 cycles, and the cyclic catalytic desorption stability of AlOOH-MAC ① , Al2O3-MAC was recorded, and the experimental results are shown in Table 3.

[0103] Table 3: Cyclic catalytic desorption stability of the catalyst of the example

[0104]

[0105] As can be seen from the above table, the catalyst AlOOH-MAC① The cycle stability of the Al2O3-MAC is excellent, and the desorption performance is almost unchanged after 6 amine desorption regeneration experiments.

[0106] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for desorption of organic amine-rich solutions, characterized in that, Includes the following steps: Under the presence of a catalyst, the organic amine-rich solution is heated and desorbed to obtain an organic amine-poor solution and gaseous CO2; The catalyst is a biochar-based catalyst, which is made from fruit shell biochar through impregnation and anaerobic pyrolysis. The fruit shell biochar is made by crushing and carbonizing fruit shells; the fruit shells are coconut shells and peanut shells; the mass ratio of coconut shells to peanut shells is 1:(0.5~2). The impregnation solution used contains an aluminum source compound and potassium hydroxide; The organic amine-rich solution is the product of organic amine solution absorbing CO2.

2. The desorption method according to claim 1, characterized in that, The concentration of aluminum source compound in the impregnation solution is 1~20wt%; the concentration of potassium hydroxide in the impregnation solution is 1~20wt%; and the ratio of the amount of fruit shell biochar to the impregnation solution is 1g:(2~5)mL.

3. The desorption method according to claim 1, characterized in that, The specific surface area of ​​the biochar-based catalyst is 900~1300 m². 2 / g; the pore size of the biochar-based catalyst is 2~40nm; the total pore volume of the biochar-based catalyst is 0.4~1.3cm³. 3 / g.

4. The desorption method according to claim 1, characterized in that, The biochar-based catalyst was prepared according to the following steps: a) The fruit shells are crushed and carbonized to obtain fruit shell biochar; the fruit shells are coconut shells and peanut shells; the mass ratio of coconut shells to peanut shells is 1:(0.5~2); b) The fruit shell biochar was impregnated in an impregnation solution containing an aluminum source compound and potassium hydroxide to obtain an impregnation mixture; c) The impregnation mixture is subjected to anaerobic pyrolysis to obtain a biochar-based catalyst.

5. In the desorption method according to claim 4, in step a), the carbonization temperature is 300~700℃; and the carbonization time is 0.5~2h.

6. In the desorption method according to claim 4, in step c), the temperature of the anaerobic pyrolysis is 300~650℃; and the time of the anaerobic pyrolysis is 0.5~3h.

7. The desorption method according to claim 1, characterized in that, The organic amine in the organic amine solution is one or more of the following: ethanolamine, N-methyldiethanolamine, piperazine, 3-diethylaminopropylamine, diethylaminoethanol, diethylenetriamine, N,N-dimethylacetamide, triethylenetetramine, and 2-amino-2-methyl-1-propanol.

8. The desorption method according to claim 7, characterized in that, The organic amines in the organic amine solution are N-methyldiethanolamine and piperazine.

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