A catalyst for carbon dioxide capture-conversion coupling in flue gas and its preparation method and application

Abstract

The present invention discloses a catalyst for carbon dioxide capture-conversion coupling in flue gas, wherein the catalyst is represented by M-M Ⅱ M Ⅲ / Ⅳ ‑LDHs‑Al2O3, where M is one or two of the noble metals Pt, Pd, Au, and Ag. Ⅱ M Ⅲ / Ⅳ ‑LDHs is layered double hydroxide, M Ⅱ Mg 2+ 、Cu 2+ 、Ni 2+ and Zn 2+ One of them, M Ⅲ / Ⅳ Fe 3+ 、Ti 4+ Cr 3+ 、Mn 4+ 、Co 3+ The weight of the catalyst is 100%, and the content of each component is as follows: M 0.5-1 wt%, M Ⅱ M Ⅲ / Ⅳ The present invention also discloses a method for preparing and applying the catalyst. The catalyst provided by the present invention can achieve a balance between CO2 capture and conversion, without the need for prior desulfurization of flue gas.

Description

Technical Field

[0001] The present invention belongs to the field of CO2 capture, conversion and storage, and specifically relates to a catalyst for coupled capture-conversion of carbon dioxide in flue gas and a preparation method and application thereof using oil column molding. Background Art

[0002] Due to the excessive use of fossil energy, the concentration of CO2 in the atmosphere has been increasing year by year, causing problems such as the greenhouse effect and environmental pollution. Since the carbon peak and carbon neutrality goals were proposed, CO2 capture and conversion have become particularly urgent and important. In modern industry, CO2 emissions mainly come from flue gas, the main components of which are CO2, H2O, O2, and trace amounts of SO2 and NOx, which brings certain difficulties to the selective capture of CO2. At present, CO2 capture mainly uses alkaline oxides or organic amines, which do not show good selectivity for SO2 and NOx. Therefore, there is an urgent need to develop a class of materials that can selectively capture CO2. At the same time, the captured CO2 materials should be converted in a timely manner to achieve a balance between capture and conversion. Summary of the Invention

[0003] In response to the defects of the existing technology, the present invention provides a catalyst for the coupled capture and conversion of carbon dioxide in flue gas, as well as its preparation method and application. Variable-valence metal ions are selected and added to the LDHs layer as a "switch" to achieve control over the capture and release of CO2, and have good selectivity for CO2; and with the assistance of precious metal nanoparticles as conversion sites, selective capture and conversion of CO2 can be achieved, providing technical support for CO2 emission reduction and its comprehensive utilization.

[0004] A catalyst for coupled capture-conversion of carbon dioxide in flue gas, the catalyst being denoted as MM Ⅱ M Ⅲ / Ⅳ -LDHs-Al2O3, wherein M is one or two of the noble metals Pt, Pd, Au, and Ag. Ⅱ M Ⅲ / Ⅳ -LDHs is a layered double hydroxide, the M Ⅱ Mg 2+ 、Cu 2+ 、Ni 2+ and Zn 2+ One of the M Ⅲ / Ⅳ Fe 3+ 、Ti 4+ Cr 3+ 、Mn 4+ 、Co 3 + The weight of the catalyst according to 100%, the content of each component is as follows: M content is 0.5-1 wt%, M ⅡM Ⅲ / Ⅳ -LDHs content is 10-30%, the balance is Al2O3; Ⅱ M Ⅲ / Ⅳ -LDHs content is expressed in M Ⅱ M Ⅲ / Ⅳ The total amount of M Ⅱ With M Ⅲ / Ⅳ The molar ratio is (2-4):1.

[0005] Preferably, the M is Pd and Pt, the M Ⅱ Mg 2+ , the M Ⅲ / Ⅳ Fe 3+ 、Ti 4+ Cr 3+ One of them.

[0006] The method for preparing the catalyst for coupled capture and conversion of carbon dioxide in flue gas is prepared by an oil column molding method, comprising the following steps:

[0007] (1) Preparation of sol:

[0008] Dissolve aluminum powder in pure water to obtain solution A; weigh M Ⅱ 、M Ⅲ / Ⅳ The corresponding metal chloride salt is dissolved in a hydrochloric acid solution to obtain a solution B; the solution B is added dropwise to the solution A at 50-100°C and the reaction is continued for 24-80 hours to obtain a sol;

[0009] (2) Molding:

[0010] The sol is placed in an ice-water bath, hexamethylenetetramine is added thereto, and the mixture is stirred to obtain a mixed sol, and the mixed sol is dropwise added into an oil column at a rate of 2-30 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the oil column is 70-120° C. and the height of the oil column is 1-12 meters; and the oil in the oil column is one of vacuum pump oil, white oil, and kerosene;

[0011] (3) Aging:

[0012] The preliminarily solidified spherical carrier is transferred to the oil in the oil column, aged at 0.1-1.0 MPa and 100-180°C for 12-48 h, then washed with deionized water for 6-12 times, dried, and calcined to obtain spherical M Ⅱ M Ⅲ / Ⅳ -LDO-Al2O3 support;

[0013] (4) Load:

[0014] The precursor of the noble metal M is dissolved in pure water to prepare the spherical M ⅡM Ⅲ / Ⅳ -LDO-Al2O3 carrier with an equal volume of precious metal impregnation solution, then add urea to it, stir and mix, and then add spherical M Ⅱ M Ⅲ / Ⅳ -LDO-Al2O3 carrier, heated at 120-130 ° C for 36-48 hours, filtered, washed to neutrality, to obtain a catalyst precursor, added a reducing agent to the catalyst precursor for reduction, dried, to obtain catalyst MM Ⅱ M Ⅲ / Ⅳ -LDHs-Al2O3.

[0015] Preferably, in step (1), the particle size of the aluminum powder is 100-500 mesh; the mass ratio of water to Al in solution A is (10-15):1; the concentration of the hydrochloric acid solution is 10-15 wt%; the amount of the hydrochloric acid solution is (Al + M Ⅱ +M Ⅲ / Ⅳ ) and HCl is calculated as 2.

[0016] Preferably, the amount of hexamethylenetetramine added in step (2) is based on the ratio of Al to NH4 + The mass ratio of the noble metal M to the urea is (2-6):1 for calculation; the molar ratio of the noble metal M to the urea in step (3) is 300:1.

[0017] More preferably, the amount of hexamethylenetetramine added in step (2) is based on the ratio of Al to NH4 + The mass ratio is (3-4):1 for calculation.

[0018] Preferably, the reducing agent is a sodium borohydride solution; the molar ratio of the sodium borohydride to the noble metal M is 5:1, and the concentration of the sodium borohydride solution is 0.05-0.06 g / mL.

[0019] Preferably, the oil in the oil column is kerosene, the temperature of the oil column is 80-100° C., and the height of the oil column is 5-6 meters.

[0020] Preferably, the drying condition is 100-120° C. for 6-8 hours, and the calcination condition is 500-600° C. for 4-5 hours.

[0021] Preferably, the precursor of the noble metal M corresponds to chloroplatinic acid, sodium chloropalladate, chloroauric acid or silver nitrate.

[0022] The application of the catalyst in carbon dioxide capture-conversion is as follows:

[0023] A. The catalyst is loaded into a fixed bed reactor, and flue gas is introduced into the fixed bed reactor. The reaction temperature is 30-100 ° C, the reaction pressure is 0.1-0.8 MPa, and the CO2 concentration is monitored until the CO2 adsorption in the flue gas reaches saturation. The flue gas space velocity is 6400 h -1 ;

[0024] B. Then switch the flue gas to H2, and the space velocity of H2 is 4000 h -1 , while introducing H2O, the space velocity of H2O is 2000h -1 , after H2O and H2 are mixed and passed through the catalyst bed, the adsorbed CO2 is hydrogenated at 50-150 ℃ and 1-5 MPa;

[0025] C. Detect the product and determine whether the captured CO2 conversion is complete based on the CO2 capture amount and the carbon content in the product;

[0026] D. Switch the atmosphere back to flue gas and repeat operations A, B, and C to start the next cycle.

[0027] Advantages of the present invention:

[0028] The catalyst prepared by the present invention can be used in the fields of CO2 capture, conversion and storage. It can realize the capture and in-situ low-temperature conversion of CO2, and can achieve a balance between the capture and conversion of CO2. It has good selectivity for CO2, SO2, and NOx in flue gas, is not interfered by SO2 and NOx, and does not require desulfurization treatment of flue gas in advance. It can provide technical support for CCUS technology to achieve the goals of "carbon peak" and "carbon neutrality". DETAILED DESCRIPTION

[0029] Example 1

[0030] 1. A catalyst for coupled carbon dioxide capture and conversion in flue gas, the catalyst being a Pd-MgFe-LDHs-Al2O3 catalyst, wherein the MgFe-LDHs is a layered double hydroxide and the Al2O3 is spherical Al2O3; based on 100% by weight of the catalyst, the contents of the components are as follows: 0.5 wt% Pd, 30% MgFe-LDHs, and the balance Al2O3; wherein the content of MgFe-LDHs is MgFe-LDHs. 2+ 、Fe 3+ Mg 2+ with Fe 3+ The molar ratio is 2:1;

[0031] 2. The method for preparing the catalyst for coupled capture and conversion of carbon dioxide in flue gas is prepared by an oil column molding method, comprising the following steps:

[0032] (1) Preparation of sol:

[0033] According to the mass ratio of water to Al of 10:1, aluminum powder with a particle size of 100-500 mesh was dissolved in pure water to obtain solution A; according to (Al+ Mg 2+ +Fe 3+ ) and HCl is calculated as 2, MgCl2·6H2O and FeCl3·6H2O are weighed and dissolved in a 12wt% hydrochloric acid solution to obtain solution B; solution B is added dropwise to solution A at 90°C, and the reaction is continued for 48h to obtain a sol;

[0034] (2) Molding:

[0035] The sol was placed in an ice water bath and the mixture was stirred at room temperature according to the conditions of Al and NH4 + The mass ratio of hexamethylenetetramine to the sol is 3:1, and the mixture is stirred to obtain a mixed sol. The mixed sol is dropwise added into a kerosene column at a rate of 5 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the kerosene column is 90° C. and the height of the kerosene column is 10 meters;

[0036] (3) Aging:

[0037] The preliminarily solidified spherical support was transferred to kerosene, aged at 0.6 MPa and 140°C for 24 h, then washed with deionized water 6 times, dried at 120°C for 6 h, and calcined at 600°C for 4 h to obtain a spherical MgFe-LDO-Al2O3 support;

[0038] (4) Load:

[0039] Sodium chloropalladate is dissolved in pure water to prepare a precious metal impregnation solution of the same volume as the spherical MgFe-LDO-Al2O3 carrier, and then urea is added thereto according to a molar ratio of precious metal Pd to urea of ​​300:1, and the mixture is stirred and mixed. Then, the spherical MgFe-LDO-Al2O3 carrier obtained in step (3) is added thereto, and the mixture is heated at 120°C for 48 hours, filtered, and washed until neutral to obtain a catalyst precursor. Then, 0.06 g / mL of sodium borohydride solution is added to the catalyst precursor according to a molar ratio of sodium borohydride to precious metal Pd of 5:1 for reduction, and the mixture is dried at 120°C for 6 hours to obtain the catalyst Pd-MgFe-LDHs-Al2O3.

[0040] Example 2

[0041] 1. A catalyst for coupled carbon dioxide capture and conversion in flue gas, the catalyst being a Pt-MgFe-LDHs-Al2O3 catalyst, wherein the MgFe-LDHs is a layered double hydroxide and the Al2O3 is spherical Al2O3; the weight of the catalyst being 100%, the contents of the components are as follows: 0.5 wt% Pt, 30% MgFe-LDHs, and the balance Al2O3; wherein the content of MgFe-LDHs is MgFe-LDHs. 2+ 、Fe 3+ Mg 2+ with Fe 3+ The molar ratio is 2:1;

[0042] 2. The method for preparing the catalyst for coupled capture and conversion of carbon dioxide in flue gas is prepared by an oil column molding method, comprising the following steps:

[0043] (1) Preparation of sol:

[0044] According to the mass ratio of water to Al of 10:1, aluminum powder with a particle size of 100-500 mesh was dissolved in pure water to obtain solution A; according to (Al+ Mg 2+ +Fe 3+ ) and HCl is calculated as 2, MgCl2·6H2O and FeCl3·6H2O are weighed and dissolved in a 12wt% hydrochloric acid solution to obtain solution B; solution B is added dropwise to solution A at 90°C, and the reaction is continued for 48h to obtain a sol;

[0045] (2) Molding:

[0046] The sol was placed in an ice water bath and the mixture was stirred at room temperature according to the conditions of Al and NH4 + The mass ratio of hexamethylenetetramine to the sol is 3:1, and the mixture is stirred to obtain a mixed sol. The mixed sol is dropwise added into a kerosene column at a rate of 5 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the kerosene column is 90° C. and the height of the kerosene column is 10 meters;

[0047] (3) Aging:

[0048] The preliminarily solidified spherical support was transferred to kerosene, aged at 0.6 MPa and 140°C for 24 h, then washed with deionized water 6 times, dried at 120°C for 6 h, and calcined at 600°C for 4 h to obtain a spherical MgFe-LDO-Al2O3 support;

[0049] (4) Load:

[0050] Chloroplatinic acid was dissolved in pure water to prepare a precious metal impregnation solution of the same volume as the spherical MgFe-LDO-Al2O3 carrier, and then urea was added thereto at a molar ratio of precious metal Pt to urea of ​​300:1, and the mixture was stirred and mixed. Then, the spherical MgFe-LDO-Al2O3 carrier obtained in step (3) was added thereto, and the mixture was heated at 120°C for 48h, filtered, and washed until neutral to obtain a catalyst precursor. Then, 0.05g / mL of sodium borohydride solution was added to the catalyst precursor at a molar ratio of sodium borohydride to precious metal Pt of 5:1 for reduction, and the mixture was dried at 120°C for 6h to obtain the catalyst Pt-MgFe-LDHs-Al2O3.

[0051] Example 3

[0052] 1. A catalyst for coupled carbon dioxide capture and conversion in flue gas, the catalyst being Au-ZnCr-LDHs-Al2O3 catalyst, wherein the ZnCr-LDHs is a layered double hydroxide and the Al2O3 is spherical Al2O3; based on 100% by weight of the catalyst, the contents of the components are as follows: 0.5 wt% Au, 30% ZnCr-LDHs, and the balance Al2O3; wherein the content of ZnCr-LDHs is based on Zn 2+ Cr 3+ Calculation, and Zn 2+ With Cr 3+ The molar ratio is 2:1;

[0053] 2. The method for preparing the catalyst for coupled capture and conversion of carbon dioxide in flue gas is prepared by an oil column molding method, comprising the following steps:

[0054] (1) Preparation of sol:

[0055] According to the mass ratio of water to Al of 10:1, aluminum powder with a particle size of 100-500 mesh was dissolved in pure water to obtain solution A; according to (Al+Zn 2+ +Cr 3+ ) and HCl is calculated as 2, ZnCl2 and CrCl3·6H2O are weighed and dissolved in a 12wt% hydrochloric acid solution to obtain solution B; solution B is added dropwise to solution A at 90°C, and the reaction is continued for 48h to obtain a sol;

[0056] (2) Molding:

[0057] The sol was placed in an ice water bath and the mixture was stirred at room temperature according to the conditions of Al and NH4 +The mass ratio of hexamethylenetetramine to the sol is 3:1, and the mixture is stirred to obtain a mixed sol. The mixed sol is dropwise added into a kerosene column at a rate of 5 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the kerosene column is 90° C. and the height of the kerosene column is 10 meters;

[0058] (3) Aging:

[0059] The preliminarily solidified spherical support was transferred to kerosene, aged at 0.6 MPa and 140°C for 24 h, then washed with deionized water 6 times, dried at 120°C for 6 h, and calcined at 600°C for 4 h to obtain a spherical ZnCr-LDO-Al2O3 support;

[0060] (4) Load:

[0061] Chloroauric acid was dissolved in pure water to prepare a precious metal impregnation solution of the same volume as the spherical ZnCr-LDO-Al2O3 carrier, and then urea was added thereto at a molar ratio of precious metal Au to urea of ​​300:1, and the mixture was stirred and mixed. Then, the spherical ZnCr-LDO-Al2O3 carrier obtained in step (3) was added thereto, and the mixture was heated at 120°C for 48h, filtered, and washed until neutral to obtain a catalyst precursor. Then, 0.05g / mL of sodium borohydride solution was added to the catalyst precursor at a molar ratio of sodium borohydride to precious metal Au of 5:1 for reduction, and the mixture was dried at 120°C for 6h to obtain the catalyst Au-ZnCr-LDHs-Al2O3.

[0062] Example 4

[0063] 1. A catalyst for coupled carbon dioxide capture and conversion in flue gas, the catalyst being an Ag-MgTi-LDHs-Al2O3 catalyst, wherein the MgTi-LDHs is a layered double hydroxide and the Al2O3 is spherical Al2O3; the weight of the catalyst is 100%, and the contents of the components are as follows: 0.5 wt% Ag, 30% MgTi-LDHs, and the balance Al2O3; wherein the content of MgTi-LDHs is MgTi-LDHs. 2+ 、Ti 4+ Mg 2+ With Ti 4+ The molar ratio is 2:1;

[0064] 2. The method for preparing the catalyst for coupled capture and conversion of carbon dioxide in flue gas is prepared by an oil column molding method, comprising the following steps:

[0065] (1) Preparation of sol:

[0066] According to the mass ratio of water to Al of 10:1, aluminum powder with a particle size of 100-500 mesh was dissolved in pure water to obtain solution A; according to (Al+Mg 2+ +Ti 4+ ) and HCl is calculated as 2 in a molar ratio, MgCl2·6H2O and TiCl4 are weighed and dissolved in a 12 wt% hydrochloric acid solution to obtain a solution B; solution B is added dropwise to solution A at 90°C, and the reaction is continued for 48 hours to obtain a sol;

[0067] (2) Molding:

[0068] The sol was placed in an ice water bath and the mixture was stirred at room temperature according to the conditions of Al and NH4 + The mass ratio of hexamethylenetetramine to the sol is 3:1, and the mixture is stirred to obtain a mixed sol. The mixed sol is dropwise added into a kerosene column at a rate of 5 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the kerosene column is 90° C. and the height of the kerosene column is 10 meters;

[0069] (3) Aging:

[0070] The preliminarily solidified spherical support was transferred to kerosene, aged at 0.6 MPa and 140°C for 24 h, then washed with deionized water 6 times, dried at 120°C for 6 h, and calcined at 600°C for 4 h to obtain a spherical MgTi-LDO-Al2O3 support;

[0071] (4) Load:

[0072] Silver nitrate was dissolved in pure water to prepare a precious metal impregnation solution of the same volume as the spherical MgTi-LDO-Al2O3 carrier, and then urea was added thereto at a molar ratio of precious metal Ag to urea of ​​300:1, and the mixture was stirred and mixed. Then, the spherical MgTi-LDO-Al2O3 carrier obtained in step (3) was added thereto, and the mixture was heated at 120°C for 48h, filtered, and washed until neutral to obtain a catalyst precursor. Then, 0.06g / mL of sodium borohydride solution was added to the catalyst precursor at a molar ratio of sodium borohydride to precious metal Ag of 5:1 for reduction, and the mixture was dried at 120°C for 6h to obtain the catalyst Ag-MgTi-LDHs-Al2O3.

[0073] Example 5

[0074] 1. A catalyst for coupled carbon dioxide capture and conversion in flue gas, the catalyst being Au-MgMn-LDHs-Al2O3 catalyst, wherein the MgMn-LDHs is a layered double hydroxide and the Al2O3 is spherical Al2O3; the weight of the catalyst being 100%, the contents of the components are as follows: 0.5 wt% Au, 30% MgMn-LDHs, and the balance Al2O3; wherein the content of MgMn-LDHs is Mg 2+ 、Mn 4+ Mg 2+ With Mn 4+ The molar ratio is 2:1;

[0075] 2. The method for preparing the catalyst for coupled capture and conversion of carbon dioxide in flue gas is prepared by an oil column molding method, comprising the following steps:

[0076] (1) Preparation of sol:

[0077] According to the mass ratio of water to Al of 10:1, aluminum powder with a particle size of 100-500 mesh was dissolved in pure water to obtain solution A; according to (Al+ Mg 2+ + Mn 4+ ) and HCl is calculated as 2, MgCl2·6H2O and MnCl4 are weighed and dissolved in a 12wt% hydrochloric acid solution to obtain solution B; solution B is added dropwise to solution A at 90°C, and the reaction is continued for 48h to obtain a sol;

[0078] (2) Molding:

[0079] The sol was placed in an ice water bath and the mixture was stirred at room temperature according to the conditions of Al and NH4 + The mass ratio of hexamethylenetetramine to the sol is 3:1, and the mixture is stirred to obtain a mixed sol. The mixed sol is dropwise added into a kerosene column at a rate of 5 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the kerosene column is 90° C. and the height of the kerosene column is 10 meters;

[0080] (3) Aging:

[0081] The preliminarily solidified spherical support was transferred to kerosene, aged at 0.6 MPa and 140°C for 24 h, then washed with deionized water 6 times, dried at 120°C for 6 h, and calcined at 600°C for 4 h to obtain a spherical MgMn-LDO-Al2O3 support;

[0082] (4) Load:

[0083] Chloroauric acid was dissolved in pure water to prepare a precious metal impregnation solution of the same volume as the spherical MgMn-LDO-Al2O3 carrier, and then urea was added thereto at a molar ratio of precious metal Au to urea of ​​300:1, and the mixture was stirred and mixed. Then, the spherical MgMn-LDO-Al2O3 carrier obtained in step (3) was added thereto, and the mixture was heated at 120°C for 48h, filtered, and washed until neutral to obtain a catalyst precursor. Then, 0.05g / mL of sodium borohydride solution was added to the catalyst precursor at a molar ratio of sodium borohydride to precious metal Pt of 5:1 for reduction, and the mixture was dried at 120°C for 6h to obtain the catalyst Au-MgMn-LDHs-Al2O3.

[0084] Example 6

[0085] 1. A catalyst for coupled carbon dioxide capture and conversion in flue gas, the catalyst being Au-CuCo-LDHs-Al2O3 catalyst, wherein the CuCo-LDHs is a layered double hydroxide and the Al2O3 is spherical Al2O3; the weight of the catalyst is 100%, and the contents of the components are as follows: 1 wt% Au, 10% CuCo-LDHs, and the balance Al2O3; wherein the content of CuCo-LDHs is based on Cu 2+ 、Co 3+ Plan, and Cu 2+ With Co 3+ The molar ratio is 2:1;

[0086] 2. The method for preparing the catalyst for coupled capture and conversion of carbon dioxide in flue gas is prepared by an oil column molding method, comprising the following steps:

[0087] (1) Preparation of sol:

[0088] According to the mass ratio of water to Al of 10:1, aluminum powder with a particle size of 100-500 mesh was dissolved in pure water to obtain solution A; according to (Al+ Cu 2+ + Co 3+ ) and HCl is calculated as 2, CuCl2·2H2O and CoCl3 are weighed and dissolved in a 10wt% hydrochloric acid solution to obtain solution B; solution B is added dropwise to solution A at 50°C, and the reaction is continued for 80h to obtain a sol;

[0089] (2) Molding:

[0090] The sol was placed in an ice water bath and the mixture was stirred at room temperature according to the conditions of Al and NH4 +The mass ratio of hexamethylenetetramine to the sol is 2:1, and the mixture is stirred to obtain a mixed sol. The mixed sol is dropwise added into a white oil column at a rate of 2 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the white oil column is 70° C. and the height of the white oil column is 12 meters;

[0091] (3) Aging:

[0092] The preliminarily solidified spherical support was transferred to white oil, aged at 0.1 MPa and 100°C for 48 h, then washed with deionized water 12 times, dried at 100°C for 8 h, and calcined at 500°C for 5 h to obtain a spherical CuCo-LDO-Al2O3 support;

[0093] (4) Load:

[0094] Chloroauric acid was dissolved in pure water to prepare a precious metal impregnation solution of the same volume as the spherical CuCo-LDO-Al2O3 carrier, and then urea was added thereto at a molar ratio of precious metal Au to urea of ​​300:1, and the mixture was stirred and mixed. Then, the spherical CuCo-LDO-Al2O3 carrier obtained in step (3) was added thereto, and the mixture was heated at 130°C for 36 hours, filtered, and washed until neutral to obtain a catalyst precursor. Then, 0.05 g / mL of sodium borohydride solution was added to the catalyst precursor at a molar ratio of sodium borohydride to precious metal Pt of 5:1 for reduction, and the mixture was dried at 100°C for 8 hours to obtain the catalyst Au-CuCo-LDHs-Al2O3.

[0095] Example 7

[0096] 1. A catalyst for coupled carbon dioxide capture and conversion in flue gas, the catalyst being Au-NiMn-LDHs-Al2O3 catalyst, wherein the NiMn-LDHs is a layered double hydroxide and the Al2O3 is spherical Al2O3; the weight of the catalyst being 100%, the contents of the components are as follows: 0.5 wt% Au, 20% NiMn-LDHs, and the balance Al2O3; wherein the content of NiMn-LDHs is based on Ni 2+ 、Mn 4+ Plan, and Ni 2+ With Mn 4+ The molar ratio is 4:1;

[0097] 2. The method for preparing the catalyst for coupled capture and conversion of carbon dioxide in flue gas is prepared by an oil column molding method, comprising the following steps:

[0098] (1) Preparation of sol:

[0099] According to the mass ratio of water to Al of 10:1, aluminum powder with a particle size of 100-500 mesh was dissolved in pure water to obtain solution A; according to (Al+Ni 2+ + Mn 4+ ) and HCl is calculated as 2, NiCl2·6H2O and MnCl4 are weighed and dissolved in a 12wt% hydrochloric acid solution to obtain solution B; solution B is added dropwise to solution A at 100°C, and the reaction is continued for 24 hours to obtain a sol;

[0100] (2) Molding:

[0101] The sol was placed in an ice water bath and the mixture was stirred at room temperature according to the conditions of Al and NH4 + The mass ratio of hexamethylenetetramine to the sol is 3:1, and the mixture is stirred to obtain a mixed sol. The mixed sol is dropwise added into a vacuum pump oil column at a rate of 30 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the vacuum pump oil column is 120° C., and the height of the vacuum pump oil column is 1 meter;

[0102] (3) Aging:

[0103] The preliminarily solidified spherical support was transferred to vacuum pump oil, aged at 1.0 MPa and 180° C. for 12 h, then washed 10 times with deionized water, dried at 120° C. for 6 h, and calcined at 600° C. for 4 h to obtain a spherical NiMn-LDO-Al2O3 support;

[0104] (4) Load:

[0105] Chloroauric acid was dissolved in pure water to prepare a precious metal impregnation solution of the same volume as the spherical NiMn-LDO-Al2O3 carrier, and then urea was added thereto at a molar ratio of precious metal Au to urea of ​​300:1, and the mixture was stirred and mixed. Then, the spherical NiMn-LDO-Al2O3 carrier obtained in step (3) was added thereto, and the mixture was heated at 130°C for 36 hours, filtered, and washed until neutral to obtain a catalyst precursor. Then, 0.05 g / mL of sodium borohydride solution was added to the catalyst precursor at a molar ratio of sodium borohydride to precious metal Au of 5:1 for reduction, and the mixture was dried at 120°C for 6 hours to obtain the catalyst Au-NiMn-LDHs-Al2O3.

[0106] Example 8

[0107] The application of the catalyst of the present invention in carbon dioxide capture-conversion is as follows:

[0108] A. The catalyst is loaded into a fixed bed reactor, and flue gas is introduced into the fixed bed reactor. The reaction temperature is 30-100 ° C, the reaction pressure is 0.1-0.8 MPa, and the CO2 concentration is monitored until the CO2 adsorption in the flue gas reaches saturation. The flue gas space velocity is 6400 h -1 ;

[0109] B. Then switch the flue gas to H2, and the space velocity of H2 is 4000 h -1 , while introducing H2O, the space velocity of H2O is 2000h -1 , after H2O and H2 are mixed and passed through the catalyst bed, the adsorbed CO2 is hydrogenated at 50-150 ℃ and 1-5 MPa;

[0110] C. The tail liquid after the reaction is collected and sent to GC for detection. The conversion of captured CO2 is determined based on the amount of CO2 captured and the amount of C in the product.

[0111] D. Switch the atmosphere back to flue gas and repeat operations A, B, and C to start the next cycle.

[0112] Performance testing

[0113] Based on Example 8, the details are as follows:

[0114] A. The catalyst is loaded into a fixed bed reactor, and flue gas is introduced into the fixed bed reactor. The reaction temperature is 30° C., the reaction pressure is 0.1 MPa, and the tail gas is analyzed by GC. The CO2 concentration is monitored until the CO2 adsorption in the flue gas reaches saturation; wherein the space velocity of the flue gas is 6400 h -1 ;

[0115] B. Then switch the flue gas to H2, and the space velocity of H2 is 4000 h -1 , while introducing H2O, the space velocity of H2O is 2000h -1 , after H2O and H2 are mixed and passed through the catalyst bed, the adsorbed CO2 is hydrogenated at 50-150 ℃ and 1-5 MPa;

[0116] C. The tail liquid after the reaction is collected and sent to GC for detection. The conversion of captured CO2 is determined based on the amount of CO2 captured and the amount of C in the product.

[0117] D. Switch the atmosphere back to flue gas and repeat operations A, B, and C to start the next cycle.

[0118] When the first carbon dioxide capture-low-temperature conversion was completed in Example 1-7, the carbon dioxide capture amount and conversion status corresponding to the unit mass of catalyst were shown in Table 1.

[0119] Table 1 Carbon dioxide capture-conversion results

[0120]

[0121] As can be seen from Table 1, the catalyst provided by the present invention can convert the captured carbon dioxide in a timely manner to achieve a balance between capture and conversion, and has good selectivity when absorbing flue gas. The capture selectivity of the absorbed flue gas for CO2 reaches more than 96%, and only contains a small amount of SO2 and NOx, so there is no need for additional desulfurization treatment of the flue gas.

Claims

1. A method for preparing a catalyst for coupled capture-conversion of carbon dioxide in flue gas, characterized in that: The catalyst is denoted as MM Ⅱ M Ⅲ / Ⅳ -LDHs-Al2O3, wherein M is one or two of the noble metals Pt, Pd, Au, and Ag. Ⅱ M Ⅲ / Ⅳ -LDHs is a layered double hydroxide, the M Ⅱ Mg 2+ 、Cu 2+ 、Ni 2+ and Zn 2+ One of the M Ⅲ / Ⅳ Fe 3 + 、Ti 4+ Cr 3+ 、Mn 4+ 、Co 3+ The weight of the catalyst according to 100%, the content of each component is as follows: M content is 0.5-1 wt%, M Ⅱ M Ⅲ / Ⅳ -LDHs content is 10-30%, the balance is Al2O3; Ⅱ M Ⅲ / Ⅳ -LDHs content is expressed in M Ⅱ M Ⅲ / Ⅳ The total amount of M Ⅱ With M Ⅲ / Ⅳ The molar ratio is (2-4):1; The catalyst is prepared by an oil column forming method, comprising the following steps: (1) Preparation of sol: Dissolve aluminum powder in pure water to obtain solution A; weigh M Ⅱ 、M Ⅲ / Ⅳ The corresponding metal chloride salt is dissolved in a hydrochloric acid solution to obtain a solution B; the solution B is added dropwise to the solution A at 50-100°C and the reaction is continued for 24-80 hours to obtain a sol; (2) Molding: The sol is placed in an ice-water bath, hexamethylenetetramine is added thereto, and the mixture is stirred to obtain a mixed sol, and the mixed sol is dropwise added into an oil column at a rate of 2-30 mL / min to obtain a preliminarily solidified spherical carrier; wherein the temperature of the oil column is 70-120° C. and the height of the oil column is 1-12 meters; and the oil in the oil column is one of vacuum pump oil, white oil, and kerosene; (3) Aging: The preliminarily solidified spherical carrier is transferred to the oil in the oil column, aged at 0.1-1.0 MPa and 100-180°C for 12-48 h, then washed with deionized water for 6-12 times, dried, and calcined to obtain spherical M Ⅱ M Ⅲ / Ⅳ -LDO-Al2O3 support; (4) Load: The precursor of the noble metal M is dissolved in pure water to prepare the spherical M Ⅱ M Ⅲ / Ⅳ -LDO-Al2O3 carrier with an equal volume of precious metal impregnation solution, then add urea to it, stir and mix, and then add spherical M Ⅱ M Ⅲ / Ⅳ -LDO-Al2O3 carrier, heated at 120-130 ° C for 36-48 hours, filtered, washed to neutrality, to obtain a catalyst precursor, added a reducing agent to the catalyst precursor for reduction, dried, to obtain catalyst MM Ⅱ M Ⅲ / Ⅳ -LDHs-Al2O3; the molar ratio of the noble metal M to urea in step (3) is 300:

1.

2. The method for preparing a catalyst for coupled capture-conversion of carbon dioxide in flue gas according to claim 1, characterized in that: The M is Pd and Pt, the M Ⅱ Mg 2+ , the M Ⅲ / Ⅳ Fe 3+ 、Ti 4+ Cr 3+ One of them.

3. The method for preparing a catalyst for coupled capture-conversion of carbon dioxide in flue gas according to claim 1, characterized in that: In step (1), the particle size of the aluminum powder is 100-500 mesh; the mass ratio of water to Al in solution A is (10-15):1; the concentration of the hydrochloric acid solution is 10-15 wt%; the amount of the hydrochloric acid solution is (Al + M Ⅱ +M Ⅲ / Ⅳ ) and HCl is calculated as 2.

4. The method for preparing a catalyst for coupled capture-conversion of carbon dioxide in flue gas according to claim 3, characterized in that: The amount of hexamethylenetetramine added in step (2) is based on the ratio of Al to NH4 + The mass ratio is (2-6):1 for calculation.

5. The method for preparing a catalyst for coupled capture-conversion of carbon dioxide in flue gas according to claim 4, characterized in that: The reducing agent is a sodium borohydride solution; the molar ratio of the sodium borohydride to the noble metal M is 5:1, and the concentration of the sodium borohydride solution is 0.05-0.06 g / mL.

6. The method for preparing a catalyst for coupled capture-conversion of carbon dioxide in flue gas according to claim 5, characterized in that: The oil in the oil column is kerosene, the temperature of the oil column is 80-100° C., and the height of the oil column is 5-6 meters.

7. The method for preparing a catalyst for coupled capture-conversion of carbon dioxide in flue gas according to claim 5, characterized in that: The drying conditions are as follows: drying at 100-120° C. for 6-8 hours; and the calcining conditions are as follows: calcining at 500-600° C. for 4-5 hours.

8. Use of a catalyst for coupled capture-conversion of carbon dioxide in flue gas in carbon dioxide capture-conversion, characterized in that: The catalyst is prepared by the preparation method according to claim 1, and the application is specifically as follows: A. The catalyst is loaded into a fixed bed reactor, and flue gas is introduced into the fixed bed reactor. The reaction temperature is 30-100 ° C, the reaction pressure is 0.1-0.8 MPa, and the CO2 concentration is monitored until the CO2 adsorption in the flue gas reaches saturation. The flue gas space velocity is 6400 h -1 ; B. Then switch the flue gas to H2, and the space velocity of H2 is 4000 h -1 , H2O was introduced at the same time, and the space velocity of H2O was 2000 h -1 , after H2O and H2 are mixed and passed through the catalyst bed, the adsorbed CO2 is hydrogenated at 50-150 ℃ and 1-5 MPa; C. Detect the product and determine whether the captured CO2 conversion is complete based on the CO2 capture amount and the carbon content in the product; D. Switch the atmosphere back to flue gas and repeat operations A, B, and C to start the next cycle.

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