Composite absorbent for enhancing carbon dioxide absorption and method for preparing the same

Abstract

The application discloses a composite absorbent for reinforcing carbon dioxide absorption and a preparation method thereof, and the composite absorbent is composed of N-methyldiethanolamine (MDEA) aqueous solution, graphite and graphene, and the preparation steps comprise the following steps: adding a certain amount of graphite powder into the MDEA aqueous solution, uniformly dispersing, then performing ultrasonic treatment by using a cell pulverizer, and then adding MEDA and water to adjust the viscosity, concentration and stability of the dispersion liquid, so that the composite absorbent can be obtained; the composite absorbent has high absorption rate, the preparation method is simple, the cost is low, and the composite absorbent has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, specifically to a composite absorbent for enhancing carbon dioxide absorption and its preparation method. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) is of great significance for reducing carbon dioxide emissions and mitigating the greenhouse effect. Methods for capturing carbon dioxide mainly include cryogenic distillation, membrane separation, adsorption, and chemical absorption. Among these, chemical absorption has advantages such as high absorption rate and large absorption capacity, and has been widely used in industry, making it a relatively mature method for CO2 capture. N-methyldiethanolamine (MDEA) is one of the most widely used CO2 chemical absorbents, possessing advantages such as low heat of reaction, low desorption temperature, chemical stability, and regeneration and recycling. However, MDEA's absorption of carbon dioxide is a liquid-film controlled process, resulting in a slow reaction rate. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an MDEA composite absorbent and its preparation method.

[0004] The technical solution of the present invention is as follows:

[0005] A composite absorbent for enhancing carbon dioxide absorption, composed of MEDA aqueous solution, graphite, and graphene.

[0006] A method for preparing a composite absorbent for enhancing carbon dioxide absorption includes the following steps:

[0007] (1) Add graphite powder to MDEA aqueous solution, stir, and ultrasonically disperse in an ultrasonic cleaner to obtain graphite-MDEA suspension.

[0008] The particle size of graphite powder is 100-325 mesh;

[0009] In aqueous MDEA solutions, the volume fraction of MDEA is 5-90%.

[0010] The preferred mass ratio of graphite powder to MDEA aqueous solution is 0.004–0.04:1;

[0011] The preferred ultrasonic cleaner has an ultrasonic power of 30-300W; the preferred ultrasonic dispersion time is 20-200 minutes.

[0012] (2) The graphite-MDEA suspension obtained in step (1) was ultrasonically exfoliated using a cell disruptor to obtain an MDEA dispersion containing graphene.

[0013] The preferred cell disruptor has an ultrasonic time of 1-10 hours and an ultrasonic power of 200-2000W;

[0014] (3) Add pure MDEA and water to the MDEA dispersion containing graphene obtained in step (2), and sonicate in an ultrasonic cleaner to obtain MDEA composite absorbent.

[0015] The purpose of adding pure MDEA and water is to adjust the viscosity, concentration and stability of the dispersion. The volumetric amounts of pure MDEA and water are 0-400% and 0-2000% of the MDEA dispersion containing graphene, respectively.

[0016] The preferred ultrasonic cleaner has an ultrasonic power of 30-300W; the preferred ultrasonic dispersion time is 20-200 minutes.

[0017] The present invention has the following beneficial effects:

[0018] (1) Compared with MDEA aqueous solution, this composite absorbent has better CO2 absorption kinetics performance, high CO2 absorption rate and low system energy consumption;

[0019] (2) The prepared MDEA composite absorbent is stable in nature. The graphite and graphene particles in it can be stably suspended in the MDEA aqueous solution and are not prone to agglomeration or sedimentation, which is conducive to maintaining the enhanced ability of the composite absorbent to absorb CO2.

[0020] (3) The preparation method adopted in this invention is simple, low in cost, easy to scale up production, and has good application prospects. Detailed Implementation

[0021] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0022] The ultrasonic cleaner used in the following examples is a KQ-300DE CNC ultrasonic cleaner manufactured by Kunshan Ultrasonic Instrument Co., Ltd.; the cell disruptor is a JY92-IIN cell disruptor manufactured by Ningbo Xinzhi Biotechnology Co., Ltd.

[0023] Example 1

[0024] (1) Weigh 4g of graphite powder with a particle size of 100 mesh and add it to 500ml of MDEA aqueous solution with a concentration of 40%. Stir thoroughly and then ultrasonically disperse it in an ultrasonic cleaner with an ultrasonic power of 120W for 10 minutes to obtain a graphite-MDEA suspension.

[0025] (2) The suspension obtained in step (1) was sonicated for 4 hours using a cell disruptor with an ultrasonic power of 200W (working for 2 seconds, with a 1-second interval) to obtain a MDEA dispersion containing graphene.

[0026] (3) Add 200ml of pure MDEA and 3300ml of water to the dispersion obtained in step (2), and then sonicate for 10 minutes in an ultrasonic cleaner with an ultrasonic power of 120W to obtain a composite absorbent.

[0027] Using a centrifugal rotating bed as the absorption reactor, under the conditions of a carbon dioxide gas flow rate of 1500 L / h, a volume concentration of 8%, a rotating bed speed of 250 r / min, and an absorbent flow rate of 400 mL / min, the composite absorbent showed a carbon dioxide absorption rate enhancement factor of 1.110 compared to a 10% MDEA aqueous solution.

[0028] Example 2

[0029] (1) Weigh 5g of graphite powder with a particle size of 270 mesh and add it to 500ml of MDEA aqueous solution with a concentration of 60%. Stir thoroughly and then ultrasonically disperse it in an ultrasonic cleaner with an ultrasonic power of 210W for 40 minutes to obtain a graphite-MDEA suspension.

[0030] (2) The suspension obtained in step (1) was sonicated for 1 hour using a cell disruptor with an ultrasonic power of 500W (working for 2 seconds, with a 1-second interval) to obtain a MDEA dispersion containing graphene.

[0031] (3) Add 100ml of pure MDEA and 3400ml of water to the dispersion obtained in step (2), and then sonicate for 40 minutes in an ultrasonic cleaner with an ultrasonic power of 210W to obtain a composite absorbent.

[0032] Using a centrifugal rotating bed as the absorption reactor, under the conditions of a carbon dioxide gas flow rate of 1500 L / h, a volume concentration of 8%, a rotating bed speed of 400 r / min, and an absorbent flow rate of 400 mL / min, the composite absorbent showed a carbon dioxide absorption rate enhancement factor of 1.096 compared to a 10% MDEA aqueous solution.

[0033] Example 3

[0034] (1) Weigh 6g of graphite powder with a particle size of 325 mesh and add it to 500ml of MDEA aqueous solution with a concentration of 80%. Stir thoroughly and then ultrasonically disperse it in an ultrasonic cleaner with an ultrasonic power of 150W for 20 minutes to obtain a graphite-MDEA suspension.

[0035] (2) The suspension obtained in step (1) was sonicated for 2 hours using a cell disruptor with an ultrasonic power of 665W (working for 2 seconds, with a 1-second interval) to obtain a MDEA dispersion containing graphene.

[0036] (3) Add 3500 ml of water to the dispersion obtained in step (2), and then sonicate it for 20 minutes in an ultrasonic cleaner with an ultrasonic power of 150 W to obtain the composite absorbent.

[0037] Using a centrifugal rotating bed as the absorption reactor, under the conditions of a carbon dioxide gas flow rate of 1500 L / h, a volume concentration of 8%, a rotating bed speed of 250 r / min, and an absorbent flow rate of 330 mL / min, the composite absorbent showed a carbon dioxide absorption rate enhancement factor of 1.130 compared to a 10% MDEA aqueous solution.

[0038] Example 4

[0039] (1) Weigh 10g of graphite powder with a particle size of 140 mesh and add it to 500ml of 50% MDEA aqueous solution. Stir thoroughly and disperse in an ultrasonic cleaner with an ultrasonic power of 300W for 60 minutes to obtain a graphite-MDEA suspension.

[0040] (2) The suspension obtained in step (1) was sonicated for 6 hours using a cell disruptor with an ultrasonic power of 1250W (working for 2 seconds, with a 1-second interval) to obtain a MDEA dispersion containing graphene.

[0041] (3) Add 150ml of pure MDEA and 3350ml of water to the dispersion obtained in step (2), and then sonicate for 20 minutes in an ultrasonic cleaner with an ultrasonic power of 300W to obtain a composite absorbent.

[0042] Using a centrifugal rotating bed as the absorption reactor, under conditions of carbon dioxide gas flow rate of 1500 L / h, volume concentration of 8%, rotating bed speed of 250 r / min, and absorbent flow rate of 400 mL / min, the composite absorbent showed a carbon dioxide absorption rate enhancement factor of 1.139 compared to a 10% MDEA aqueous solution.

[0043] Example 5

[0044] (1) Weigh 8g of graphite powder with a particle size of 200 mesh and add it to 500ml of MDEA aqueous solution with a concentration of 70%. Stir thoroughly and disperse in an ultrasonic cleaner with an ultrasonic power of 240W for 120 minutes to obtain a graphite-MDEA suspension.

[0045] (2) The suspension obtained in step (1) was sonicated for 5 hours using a cell disruptor with an ultrasonic power of 875W (working for 2 seconds, with a 1-second interval) to obtain a MDEA dispersion containing graphene.

[0046] (3) Add 450ml of pure MDEA and 3050ml of water to the dispersion obtained in step (2), and then sonicate for 120 minutes in an ultrasonic cleaner with an ultrasonic power of 240W to obtain a composite absorbent.

[0047] Using a centrifugal rotating bed as the absorption reactor, under conditions of carbon dioxide gas flow rate of 1500 L / h, volume concentration of 8%, rotating bed speed of 250 r / min, and absorbent flow rate of 400 mL / min, the composite absorbent showed a carbon dioxide absorption rate enhancement factor of 1.144 compared to a 20% MDEA aqueous solution.

[0048] Example 6

[0049] (1) Weigh 16g of graphite powder with a particle size of 170 mesh and add it to 500ml of 90% MDEA aqueous solution. Stir thoroughly and then ultrasonically disperse it in an ultrasonic cleaner with an ultrasonic power of 180W for 30 minutes to obtain a graphite-MDEA suspension.

[0050] (2) The suspension obtained in step (1) was sonicated for 2 hours using a cell disruptor with an ultrasonic power of 1000W (working for 2 seconds, with a 1-second interval) to obtain a MDEA dispersion containing graphene.

[0051] (3) Add 350ml of pure MDEA and 3150ml of water to the dispersion obtained in step (2), and then sonicate for 30 minutes in an ultrasonic cleaner with an ultrasonic power of 180W to obtain a composite absorbent.

[0052] Using a centrifugal rotating bed as the absorption reactor, under conditions of carbon dioxide gas flow rate of 1500 L / h, volume concentration of 10%, rotating bed speed of 250 r / min, and absorbent flow rate of 400 mL / min, the composite absorbent showed a carbon dioxide absorption rate enhancement factor of 1.130 compared to a 20% MDEA aqueous solution.

Claims

1. A composite absorbent for enhancing carbon dioxide absorption, characterized in that, The composite absorbent is composed of MDEA aqueous solution, graphite, and graphene; The preparation method of the composite absorbent is as follows: (1) Add graphite powder to MDEA aqueous solution, stir, and ultrasonically disperse in an ultrasonic cleaner to obtain graphite-MDEA suspension; (2) The graphite-MDEA suspension obtained in step (1) was ultrasonically exfoliated using a cell disruptor to obtain an MDEA dispersion containing graphene. (3) Add pure MDEA and water to the MDEA dispersion containing graphene obtained in step (2), and sonicate in an ultrasonic cleaner to obtain MDEA composite absorbent.

2. The composite absorbent for enhancing carbon dioxide absorption as described in claim 1, characterized in that, In step (1) of the preparation method, the particle size of the graphite powder is 100-325 mesh.

3. The composite absorbent for enhancing carbon dioxide absorption as described in claim 1, characterized in that, Preparation method steps (1) In the MDEA aqueous solution, the volume fraction of MDEA is 5-90%.

4. The composite absorbent for enhancing carbon dioxide absorption as described in claim 1, characterized in that, In step (1) of the preparation method, the mass ratio of graphite powder to MDEA aqueous solution is 0.004~0.04:

1.

5. The composite absorbent for enhancing carbon dioxide absorption as described in claim 1, characterized in that, In step (2) of the preparation method, the time for sonication of the cell disruptor is 1-10 hours and the ultrasonic power is 200-2000W.

6. The composite absorbent for enhancing carbon dioxide absorption as described in claim 1, characterized in that, In step (3) of the preparation method, the volume of pure MDEA and water used are 0-400% and 0-2000% of the MDEA dispersion containing graphene, respectively.

7. The composite absorbent for enhancing carbon dioxide absorption as described in claim 1, characterized in that, In step (1) or step (3) of the preparation method, the ultrasonic power of the ultrasonic cleaner is 30-300W; the ultrasonic dispersion time is 20-200 minutes.