A carbon dioxide-fixing enzyme adsorbent material, its preparation method and application

Abstract

The present invention belongs to the technical field of enzyme engineering, and provides a carbon dioxide-fixing enzyme adsorbent material, a preparation method and an application thereof. The adsorbent material belongs to a nanoscale composite, and comprises the following components in parts by weight: 5-300 of calcium oxide and 1-30 of molecular sieve; the nanoscale composite is used for immobilizing enzyme preparations including carbonic anhydrase preparation, cellulase, lipase, lysozyme, glucose oxidase. The carbon dioxide-fixing enzyme adsorbent material of the present invention is used for the adsorption and in-situ utilization of carbon dioxide in flue gas, realizes the selective absorption and fixation of carbon dioxide under normal temperature and pressure conditions, reduces the reaction energy consumption, and realizes the low-cost adsorption and utilization of carbon dioxide.

Description

Technical Field

[0001] The present invention belongs to the technical field of enzyme engineering, and particularly relates to a carbon dioxide-fixing enzyme adsorbent material, a preparation method thereof, and an application thereof. Background Art

[0002] In-Situ Carbon Capture and Utilization (ICCU) technology is an innovative carbon dioxide capture and utilization technology that can complete two reaction processes of carbon capture and carbon utilization in the same catalyst. The ICCU technology eliminates the economic cost of CO2 compression and transportation in traditional carbon capture and storage (CCU) technology, thereby improving the energy efficiency and technical economy of the entire process. The ultra-high energy-consuming CO2 desorption step in traditional CCU technology can be replaced by the desorption of catalytic reaction products in ICCU, thereby reducing the energy consumption for the regeneration of adsorption sites. The ICCU technology has broad application prospects in multiple fields. The ICCU technology can be applied to the capture of CO2 in flue gases such as power plants, transportation, and industrial waste gases, and catalytically convert it into valuable fuels or production raw materials. ICCU can effectively reduce CO2 emissions in flue gases while realizing the recycling of resources, and can also be applied to the capture of extremely low-concentration CO2 in the air. The ICCU technology theoretically has great advantages in energy conservation and consumption reduction, but its technology maturity is still a challenge. The ICCU technology requires more complex catalysts and reaction conditions, which increases its R & D cost and difficulty. The high cost of the ICCU technology limits its promotion and application. In the ICCU technology, achieving efficient and selective CO2 capture and conversion is the key. However, due to the relatively high chemical stability of CO2, its conversion process often requires a relatively high energy input and specific catalysts. This may lead to low reaction efficiency or the generation of by-products, affecting the purity and quality of the products. In addition, in addition to CO2, flue gases also contain other pollutants (such as NO x , SO x , particulate matter, etc.), and these pollutants may have an adverse impact on the performance of the catalyst, reducing the reaction efficiency and selectivity.

[0003] Therefore, how to reduce costs and lower the reaction energy consumption on the premise of achieving efficient carbon dioxide fixation and effective carbon utilization is a problem that needs to be solved. Summary of the Invention

[0004] Aiming at the problems of carbon dioxide fixation and recycling in the existing technology, the purpose of the present invention is to provide a carbon dioxide-fixing enzyme adsorbent material, its preparation method and application. By using the adsorbent material described in the present application to treat carbon dioxide in flue gas, it is possible to achieve efficient adsorption of carbon dioxide at room temperature and in-situ fixation, reduce the pressure and temperature requirements for the adsorbent loading device during the adsorption process, and reduce energy consumption.

[0005] It is used for the fixation and utilization of carbon dioxide in flue gas or the environment, can effectively reduce carbon dioxide emissions and achieve carbon cycling, and avoid high-energy-consuming experimental conditions during this process, realizing low-cost and low-energy-consuming carbon cycling. The adsorption performance and effect of existing adsorbents on carbon dioxide are affected by temperature and pressure conditions. During the carbon dioxide capture process, higher temperature and pressure conditions are required, resulting in higher energy consumption. Chemical adsorbents such as amine solvents perform well in selective absorption, but also have higher regeneration energy consumption. Therefore, the inventors have conducted research on this and found that through the immobilized enzyme technology, it is possible to form an efficient carbon dioxide adsorption layer on the surface of nano-scale medium micropores, construct an alkaline reaction condition by mixing calcium oxide and molecular sieve, promote the adsorption and in-situ utilization of carbon dioxide on the adsorption surface, increase the adsorption efficiency, reduce energy consumption, and at the same time, the adsorbent can be regenerated under weak alkaline conditions, which is a new material for efficient energy-saving carbon dioxide fixation and reuse. Carbon dioxide in the gas is selectively adsorbed by the carbonic anhydrase immobilized on the surface of the adsorbent, efficiently catalyzes the fixation of carbon dioxide into carbonic acid, and the formed carbonic acid further reacts in-situ with the alkaline components in the adsorption material, represented by calcium oxide, to generate calcium carbonate.

[0006] In view of this, the inventors provide the following solutions of the present invention.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The first aspect of the present invention provides a carbon dioxide-fixing enzyme adsorbent material, which belongs to a nano-scale composite and comprises the following components in parts by weight:

[0009] Calcium oxide 5 - 300

[0010] Molecular sieve 1 - 30;

[0011] The nano-scale composite is used for immobilizing enzyme preparations including carbonic anhydrase preparation, formate dehydrogenase, and carboxylase.

[0012] Further, the molecular sieve includes 5A, 4A, and 3A molecular sieves.

[0013] The second aspect of the present invention provides a preparation method of the carbon dioxide-fixing enzyme adsorbent material described in the first aspect, comprising the following steps:

[0014] Step 1, preparation of the adsorption matrix: Mix calcium oxide and molecular sieve according to the parts by weight described in Claim 1, and grind them in a ball mill. First, perform coarse particle grinding to grind the raw materials into a coarse product with a particle size not greater than 500 nm. After sieving, the coarse product is further finely ground until the particle size distribution reaches 100 - 50 nm;

[0015] Step 2, enzyme preparation: Dissolve the enzyme preparation in a solvent to prepare an enzyme solution with a concentration of 1 - 10 mg / mL;

[0016] Step 3, enzyme immobilization: Add the adsorption matrix prepared in Step 1 and the enzyme solution prepared in Step 2 to an incubation tube in a ratio of adsorption matrix mass: enzyme solution volume (mg: mL) of 10 - 5:1, and perform oscillating incubation at a temperature of 30 - 50 °C;

[0017] Step 4, rinsing of the adsorption material: Resuspend and centrifuge the incubated adsorption material with a solvent, and elute it until the ultraviolet absorption value of the eluate at 280 nm is less than 0.2;

[0018] Step 5, freeze - drying and storage: Freeze - dry the immobilized enzyme adsorption material in the presence of a freeze - drying protectant to prepare the finished adsorption material.

[0019] Furthermore, in Step 2 and Step 4, the solvent is one of PBS, phosphate buffer solution, TAE, or TrisHCl buffer solution.

[0020] Furthermore, in Step 5, the freeze - drying protectant is one of sugars, fatty acids, amino acids, polyols, or thiol reagents.

[0021] Furthermore, in Step 5, the addition amount of the freeze - drying protectant is 1% - 3% of the mass of the enzyme preparation.

[0022] Furthermore, in Step 5, the conditions for freeze - drying treatment are: vacuum degree 0 - 10 Pa, temperature - 20 °C to - 30 °C, and freeze - drying time 12 h - 24 h.

[0023] The third aspect of the present invention provides a method for treating flue gas using the carbon dioxide - fixing enzyme adsorption material described in the first aspect, including the following steps:

[0024] The flue gas to be treated enters the adsorption device from the inlet pipeline through the first gas on - line detection device. The adsorption device is filled with the carbon dioxide - fixing enzyme adsorption material described in the first aspect;

[0025] In the adsorption device, carbon dioxide in the flue gas to be treated is selectively adsorbed, captured, and in - situ utilized by the adsorption material;

[0026] The treated flue gas is discharged outward through the second gas on - line detection device and the outlet pipeline.

[0027] Further, the adsorption device is connected to a temperature control device so that the temperature of the adsorption material in the adsorption device is maintained at 30°C to 50°C.

[0028] The beneficial effects of the present invention compared with the prior art are as follows:

[0029] 1. In the prior art, the fixation of carbon dioxide in flue gas often requires high-energy-consuming conditions such as high temperature and high pressure, with high costs and low efficiency; the carbon dioxide-fixing enzyme adsorption material described in this application uses calcium oxide and zeolite nanocomposite as the main matrix, and the carbonic anhydrase fixed by the adsorption matrix can achieve specific adsorption and efficient catalysis of carbon dioxide under normal temperature conditions, improving the selectivity of the reaction CO2(g) + H2O → H2CO3 and the purity of the product; at the same time, the alkaline component (calcium oxide) in the matrix can realize the in-situ conversion and utilization of the fixed carbon dioxide;

[0030] 2. The carbon dioxide-fixing enzyme adsorption material described in this application is used for the adsorption and in-situ utilization of carbon dioxide in flue gas and the environment, which can effectively reduce carbon dioxide emissions, improve the adsorption efficiency, reduce energy consumption, and realize the fixation and utilization of carbon dioxide;

[0031] 3. The carbon dioxide-fixing enzyme adsorption material described in this application has good adsorption stability during use. This adsorption material can be regenerated using a low-concentration sodium hydroxide solution, with low regeneration energy consumption and high regeneration efficiency, which can reduce the energy consumption cost. In the prior art, single metal oxides used as carbon dioxide absorbents, such as magnesium oxide, sodium oxide, calcium oxide, etc., usually carry out the carbon dioxide adsorption process at a high temperature above 300°C, and a reversible chemical reaction occurs between carbon dioxide and the metal compound, while the desorption process requires calcination to above 300°C. Although traditional zeolites have a high adsorption capacity and selectivity and a lower regeneration temperature, their stability is poor. The present invention uses enzyme engineering technology to immobilize the selective carbon dioxide adsorption catalyst carbonic anhydrase on the surface of the adsorbent, reducing the reaction temperature while improving the reaction selectivity and efficiency, reducing the regeneration energy consumption, and fixing carbon at low cost. Taking coal-fired flue gas as the gas source, after desulfurization and dust removal, the carbon dioxide concentration is 6% - 10%. After the carbon dioxide and moisture content in the flue gas are measured by an on-line device, it enters the capture system. The adsorption device is filled with a certain height of carbon dioxide adsorbent. The regeneration method is to put the adsorbent into a low-concentration sodium hydroxide solution for regeneration, and it can be reused after low-temperature drying. The CO2 adsorption capacity can reach 0.72 mmol / g at room temperature and 0.80 mmol / g at 60°C. Description of the Drawings

[0032] The present invention will be further described below with reference to the drawings and embodiments:

[0033] Figure 1 Schematic structural diagram of the carbon dioxide adsorption and fixation experimental device described in the embodiment;

[0034] Figure 2 Pore size distribution diagram of the nano matrix in Example 1;

[0035] Figure 3 Electron micrograph of the carbon dioxide-fixing enzyme adsorption material described in Example 1;

[0036] Figure 4 Electron micrograph of the carbon dioxide-fixing enzyme adsorption material described in Example 2;

[0037] Figure 5 Electron micrograph of the carbon dioxide-fixing enzyme adsorption material described in Example 3;

[0038] Figure 6 Comparison result diagram of the carbon dioxide-fixing enzyme adsorption material and activated carbon adsorption in Example 4;

[0039] Figure 7 Comparison result diagram of the carbon dioxide-fixing enzyme adsorption material and organic amine adsorbent in Example 5;

[0040] Figure 8 Dynamic adsorption schematic diagram of different adsorbents (a, b, c correspond to the adsorption materials in Examples 1 to 3 respectively) in Example 6. Detailed implementation manners

[0041] The examples given are for better illustration of the present invention, but the content of the present invention is not limited only to the examples given. Therefore, those skilled in the art who make non-essential improvements and adjustments to the implementation manners according to the above-mentioned invention content still fall within the protection scope of the present invention.

[0042] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0043] The present invention will be described in detail below through examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention in an exemplary manner, and are not used to limit the present invention.

[0044] Some raw materials involved in the following examples are shown in Table 1.

[0045] Table 1

[0046] reagent grade manufacturer calcium oxide reagent grade Shanghai Aladdin Biochemical Technology Co., Ltd. molecular sieve 5 Å, pellets, 2.5 - 3.5 mm Shanghai Aladdin Biochemical Technology Co., Ltd. carbonic anhydrase ≥3,000 units / mg dry weight Shanghai Aladdin Biochemical Technology Co., Ltd. phosphate buffer solution pH6.5 (25℃) Shanghai Aladdin Biochemical Technology Co., Ltd. PBS PBS solution, pH 7.5, ultrapure grade Shanghai Aladdin Biochemical Technology Co., Ltd. TrisHCl ≥99% Shanghai Aladdin Biochemical Technology Co., Ltd. TAE pH 8.2 - 8.4 Shanghai Aladdin Biochemical Technology Co., Ltd.

[0047] Experimental instruments are shown in Table 2.

[0048] Table 2

[0049] instrument name model manufacturer lyophilizer Heto PowerDry PL9000 Thermo Fisher Scientific

[0050] Example 1

[0051] This example provides a carbon dioxide-fixing enzyme adsorption material, and the preparation method includes the following steps:

[0052] Mix calcium oxide and 5A molecular sieve in a ratio of 5:1 by parts, and grind them with a ball mill. First, perform coarse particle grinding to grind the raw materials into a crude product with a particle size not greater than 500 nm, then sieve it, and further finely grind the crude product until the particle size distribution reaches ~70 nm to obtain an adsorption matrix; the pore size distribution of the adsorption matrix is as Figure 2 shown.

[0053] Dissolve the carbonic anhydrase preparation in PBS solvent to prepare an enzyme solution with a concentration of 3 mg / mL; add the adsorption matrix and the enzyme solution to an incubation tube in a ratio of adsorption matrix mass: enzyme solution volume (mg:mL) of 10:1, and oscillate and incubate at a temperature of 37 °C. Resuspend and centrifuge the obtained adsorption material after incubation with PBS blank dissolution solution, and elute until the ultraviolet absorption value of the eluate at 280 nm is less than 0.2. Store it in a freeze-dried manner. The fixed enzyme adsorption material is freeze-dried under the condition of a freeze-drying protectant, usually 8%-10% (mass-to-volume ratio) of trehalose and mannitol as the freeze-drying protectant, to prepare the finished product of the carbon dioxide-fixing enzyme adsorption material.

[0054] Use an electron microscope to observe the structure of the prepared finished adsorption material, as Figure 3 shown.

[0055] Example 2

[0056] This example provides a carbon dioxide-fixing enzyme adsorption material, and the preparation method includes the following steps:

[0057] Mix calcium oxide and 3A molecular sieve in a ratio of 7:3 by parts, and grind them with a ball mill. First, perform coarse particle grinding to grind the raw materials into a crude product with a particle size not greater than 500 nm, then sieve it, and further finely grind the crude product until the particle size distribution reaches ~50 nm to obtain an adsorption matrix.

[0058] Dissolve the carbonic anhydrase preparation in TAE solvent to prepare an enzyme solution with a concentration of 1 mg / mL; add the adsorption matrix and the enzyme solution to an incubation tube at a ratio of adsorption matrix mass: enzyme solution volume (mg: mL) of 5:1, shake and incubate at a temperature of 37 °C. Resuspend and centrifuge the obtained adsorption material after incubation with TAE blank dissolution solution, and elute until the ultraviolet absorption value of the eluate at 280 nm is less than 0.2. Store by freeze-drying. Freeze-dry the fixed enzyme adsorption material in the presence of a freeze-drying protectant, usually 8%-10% (mass to volume) of trehalose and mannitol as the freeze-drying protectant, to prepare the finished product of the carbon dioxide-fixing enzyme adsorption material. Use an electron microscope to observe the structure of the obtained finished adsorption material, as Figure 4 shown.

[0059] Example 3

[0060] This example provides a carbon dioxide-fixing enzyme adsorption material, and the preparation method includes the following steps:

[0061] Mix calcium oxide and 4A molecular sieve in a ratio of 6:4 by parts, and grind them with a ball mill. First, perform coarse particle grinding to grind the raw materials into a crude product with a particle size not greater than 500 nm, and then sieve it. Further finely grind the crude product until the particle size distribution reaches ~80 nm to obtain the adsorption matrix.

[0062] Dissolve the carbonic anhydrase preparation in TAE solvent to prepare an enzyme solution with a concentration of 5 mg / mL; add the adsorption matrix and the enzyme solution to an incubation tube at a ratio of adsorption matrix mass: enzyme solution volume (mg: mL) of 8:1, shake and incubate at a temperature of 37 °C. Resuspend and centrifuge the obtained adsorption material after incubation with TAE blank dissolution solution, and elute until the ultraviolet absorption value of the eluate at 280 nm is less than 0.2. Store by freeze-drying. Freeze-dry the fixed enzyme adsorption material in the presence of a freeze-drying protectant to prepare the finished product of the carbon dioxide-fixing enzyme adsorption material, usually 8%-10% (mass to volume) of trehalose and mannitol as the freeze-drying protectant. Use an electron microscope to observe the structure of the obtained finished adsorption material, as Figure 5 shown.

[0063] Example 4 - Laboratory determination of the adsorption capacity of the carbon dioxide-fixing enzyme adsorption material

[0064] This example is to detect the carbon fixation effect of the carbon dioxide-fixing enzyme adsorption material prepared in Example 1, and the Figure 1 shown reactor is selected. Use a simulated flue gas of 12% carbon dioxide and 88% air, and the test is carried out at room temperature and normal pressure. The control adsorption material is 5A molecular sieve.

[0065] The method for flue gas treatment includes the following steps:

[0066] The introduced simulated flue gas enters the adsorption device 2 from the intake pipeline through the first on-line gas detection device 1. The adsorption device is filled with the carbon dioxide-fixing enzyme adsorption material or molecular sieve described in Example 1.

[0067] When the adsorption device 2 contains the adsorption material described in Example 1, carbon dioxide in the simulated flue gas is selectively adsorbed, captured and in-situ utilized by the adsorption material.

[0068] The treated simulated flue gas is discharged outwards through the second on-line gas detection device 3 and the outlet pipeline.

[0069] According to the set conditions, an adsorption reaction is carried out between carbon dioxide and the adsorption material sample for 20 minutes. The adsorption material and carbon dioxide gas undergo static adsorption under fixed temperature and pressure. As Figure 6 shown, from the analysis of the adsorption capacity, the carbon dioxide-fixing enzyme adsorption material exceeds the adsorption capacity of the molecular sieve by more than 50%. It shows that the carbon dioxide-fixing enzyme adsorption material described in Example 1 can effectively adsorb carbon dioxide.

[0070] Example 5 - Laboratory determination of the adsorption capacity of the carbon dioxide-fixing enzyme adsorption material

[0071] This example is to detect the carbon fixation effect of the carbon dioxide-fixing enzyme adsorption material prepared in Example 2. The reactor shown in Figure 1 is selected, and simulated flue gas of 15% carbon dioxide and 85% N2 is used. The test is carried out at room temperature and atmospheric pressure, and the control adsorption material is an organic amine adsorbent. The method for flue gas treatment refers to Example 4. The carbon dioxide-fixing enzyme adsorption material and the organic amine adsorbent are respectively loaded into the adsorption device, and the simulated flue gas is introduced. According to the set conditions, an adsorption reaction is carried out between carbon dioxide and the sample for 20 minutes. The adsorption material and carbon dioxide gas undergo static adsorption under fixed temperature and pressure. As Figure 7 shown, from the analysis of the adsorption capacity, the carbon dioxide-fixing enzyme adsorption material exceeds the adsorption capacity of the molecular sieve by more than 30%. It shows that the carbon dioxide-fixing enzyme adsorption material described in Example 2 can effectively adsorb carbon dioxide.

[0072] Example 6 - Laboratory determination of the relationship between the adsorption capacity of the carbon dioxide-fixing enzyme adsorption material and temperature

[0073] This example is to detect the relationship between the adsorption capacity of the immobilized enzyme adsorption materials described in Examples 1 to 3 and temperature. After preparing the different carbon dioxide immobilized enzyme adsorption materials, an atmospheric pressure variable temperature device is selected, and simulated flue gas with 15% carbon dioxide and 85% N2 is used to detect the change of the adsorption capacity of the adsorbent with temperature. For the flue gas treatment device and method, refer to Example 4. The carbon dioxide immobilized enzyme adsorption materials are respectively loaded into the adsorption device, and the simulated flue gas is introduced. According to the set conditions, carbon dioxide is made to react with the sample for 30 minutes. Dynamic adsorption occurs between the adsorbent and carbon dioxide gas. As Figure 8 shown, from the analysis of the adsorption capacity, the adsorption capacity of the carbon dioxide immobilized enzyme adsorption material is related to temperature. It shows that the carbon dioxide immobilized enzyme adsorption materials described in Examples 1 to 3 can effectively adsorb carbon dioxide, and its adsorption capacity can be further adjusted by the reaction temperature.

[0074] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred arrangement, those of ordinary skill in the art should understand that the technical solution of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for treating flue gas using a carbon dioxide-fixing enzyme adsorption material, characterized in that The method includes the following steps: The flue gas to be treated enters the adsorption device (2) from the intake pipeline through the first on-line gas detection device (1). The adsorption device is filled with a carbon dioxide-fixing enzyme adsorption material. The carbon dioxide-fixing enzyme adsorption material belongs to a nanoscale composite and includes the following components in parts by weight: Calcium oxide 5 - 300 Molecular sieve 1 - 30; And a carbonic anhydrase preparation fixed on the calcium oxide and molecular sieve composite; The molecular sieve is one of 5A, 4A or 3A molecular sieves; In the adsorption device, carbon dioxide in the flue gas to be treated is selectively adsorbed, captured and in-situ utilized by the adsorption material. The treated flue gas is discharged outwards through the second on-line gas detection device (3) and the outlet pipeline.

2. The method according to claim 1, wherein The preparation method of the carbon dioxide-fixing enzyme adsorption material includes the following steps: Step 1, prepare the adsorption matrix: According to the parts by weight of calcium oxide 5 - 300 and molecular sieve 1 - 30, mix calcium oxide and molecular sieve, and grind them with a ball mill. First, perform coarse particle grinding to grind the raw materials into a coarse product with a particle size not greater than 500 nm. After sieving, the coarse product is further finely ground until the particle size distribution reaches 100 - 50 nm. Step 2, enzyme preparation: Dissolve the enzyme preparation in a solvent to prepare an enzyme solution with a concentration of 1 - 10 mg / mL. Step 3, enzyme immobilization: Add the adsorption matrix prepared in Step 1 and the enzyme solution prepared in Step 2 to the incubation tube according to the ratio of adsorption matrix mass: enzyme solution volume of 10 - 5:1, and perform oscillating incubation at a temperature of 30 - 50°C. Step 4, adsorption material washing: Resuspend and centrifuge the incubated adsorption material with a solvent, and elute it until the ultraviolet absorption value of the eluate at 280 nm is less than 0.

2. Step 5, freeze-drying and storage: Freeze-dry the immobilized enzyme adsorption material in the presence of a freeze-drying protectant to prepare the finished adsorption material.

3. The method according to claim 2, wherein In Step 2 and Step 4, the solvent is one of PBS, phosphate buffer solution, TAE or TrisHCl buffer solution.

4. The method according to claim 2, wherein In Step 5, the freeze-drying protectant is one of sugars, fatty acids, amino acids, polyols or thiol reagents.

5. The method according to claim 2 or 4, characterized in that In Step 5, the addition amount of the freeze-drying protectant is 1% - 3% of the mass of the enzyme preparation.

6. The method according to claim 2, characterized in that In Step 5, the conditions for freeze-drying treatment are: vacuum degree 0 - 10 Pa, temperature -20°C to -30°C, and freeze-drying time 12 h - 24 h.

7. The method according to claim 2, wherein The adsorption device (2) is connected to a temperature control device so that the temperature of the adsorption material in the adsorption device is maintained at 30°C - 50°C.

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