Preparation method and application of cerium-nickel bimetal synergistic modified steel slag-based oxygen carrier

Abstract

The invention discloses a preparation method of a cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier, and belongs to the technical field of industrial solid waste resource utilization and sludge treatment.The preparation method comprises the steps that steel slag is used as a carrier, and the cerium-nickel bimetal synergistically modified porous nanostructure oxygen carrier is prepared through an ultrasonic-assisted dipping and microwave-assisted roasting technology; the oxygen carrier has high specific surface area, rich active sites and good oxygen transmission capacity and catalytic performance, the yield and purity of hydrogen in the sludge gasification process can be remarkably improved, the cycling stability and the anti-agglomeration performance of the oxygen carrier are improved, and the dual purposes of industrial solid waste recycling and efficient sludge treatment are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial solid waste resource utilization and sludge treatment, and specifically relates to a preparation method of a cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier and the application of the cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier in chemical looping gasification of sludge for hydrogen production. Background Art

[0002] With the acceleration of the urbanization process, the output of municipal sludge has increased rapidly. Sludge contains a large amount of organic matter, heavy metals and pathogenic microorganisms. If not properly treated, it will cause serious pollution to the environment. Traditional sludge treatment methods such as landfill, incineration and land use have problems such as large land occupation, secondary pollution and resource waste.

[0003] Chemical looping gasification technology provides a way to solve the above sludge treatment dilemma. This technology uses an oxygen carrier as a medium, and through a stepwise oxidation-reduction reaction, the organic matter in the sludge is directionally converted into syngas, while realizing the stabilization of heavy metals and the synergistic removal of pollutants. Compared with traditional incineration, it has higher energy utilization efficiency and can effectively control the emission of pollutants such as NOx. This technology realizes the efficient decomposition of sludge organic matter to produce hydrogen and the solidification and stabilization of heavy metals in the sludge, achieving the goals of sludge reduction, harmlessness, resource utilization and stabilization, and providing a solution for sludge treatment.

[0004] The screening of high-performance oxygen carriers is the key to the development of chemical looping gasification technology. Existing technologies have used single metal oxides such as Fe, Ni, Cu or CaSO4 as oxygen carriers, but there are problems such as high cost and insufficient stability, and there is still great room for improvement in performance. The current research on oxygen carriers focuses on the collaborative development of composite systems and industrial solid waste resource utilization (steel slag, phosphogypsum, etc.). By doping metals to modify the oxygen carriers made of waste residues (steel slag, phosphogypsum, etc.), the problems of less active ingredients and poor reaction activity of the oxygen carriers are solved, the use cost of the oxygen carriers is reduced, the storage and pollution of waste residues are reduced, and both economic and environmental benefits are achieved. Summary of the Invention

[0005] The present invention provides a preparation method of a cerium-nickel bimetal synergistically modified porous nanostructured steel slag-based oxygen carrier. Through an ultrasonic-assisted impregnation and microwave-assisted calcination process, an oxygen carrier with a high specific surface area, rich active sites and good oxygen transport ability is prepared, significantly improving the hydrogen production and purity in the chemical looping gasification process of sludge, enhancing the cyclic stability and anti-agglomeration performance of the oxygen carrier, and achieving the dual goals of industrial solid waste resource utilization and efficient sludge treatment.

[0006] The preparation method of the cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier of the present invention is as follows: 1. Crush and screen the steel slag to a particle size less than 80 mesh; The steel slag is the pressurized hot-smothered steel slag produced by the iron and steel industry; 2. Prepare a mixed solution containing cerium salt and nickel salt, where the mass ratio of metal ions to steel slag is 5-20%, the metal salt concentration in the mixed solution containing cerium salt and nickel salt is 0.1-0.3 mol / L, and the mass ratio of cerium salt to nickel salt is 1:1-5:1. Ultrasonic stirring is used during the preparation; 3. Add the sieved steel slag into the mixed solution containing cerium salt and nickel salt, and ultrasonically impregnate for 2-3 hours. The ultrasonic frequency is 40 kHz and the power is 300 W; the pH value of the mixed solution containing cerium salt and nickel salt is 5-7 4. Dry the impregnated steel slag at 105-120 °C, and then calcine it under microwave conditions at 800-900 °C for 20-30 min to obtain a cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier; the microwave power is 800-900 W.

[0007] The specific benefits of the present invention are as follows: 1. High oxygen-carrying capacity and catalytic performance: Through the synergistic modification of cerium-nickel bimetals, the oxygen carrier exhibits excellent oxygen transport capacity and catalytic performance during the chemical-looping gasification process, significantly increasing the yield and purity of hydrogen; 2. Excellent cycle stability and anti-agglomeration performance: The oxygen carrier with a porous nanostructure can still maintain a stable structure and performance after multiple cycles of use, avoiding the problems of easy agglomeration and decreased activity of traditional oxygen carriers at high temperatures; 3. Resource utilization of industrial solid wastes: Using steel slag as a carrier not only reduces the preparation cost of the oxygen carrier but also realizes the resource utilization of industrial solid wastes, with good economic and environmental benefits; 4. Simple preparation process: The ultrasonic-assisted impregnation and microwave-assisted calcination processes are adopted, with simple operation and easy industrial production. Specific embodiments

[0008] The technical solutions of the present invention will be further described in detail below through examples. However, the content of the present invention is not limited thereto. The methods in the following examples are conventional methods unless otherwise specified, and the materials, reagents, etc. are obtained from commercial sources or prepared by conventional methods unless otherwise specified; Example 1

[0009] (1) Crush and sieve the steel slag to a particle size less than 80 mesh; (2) Weigh cerium nitrate and nickel nitrate in a ratio of 3:1 by mass, add water to prepare a mixed solution with a concentration of 0.2 mol / L (pH 6), and ultrasonically stir for 30 minutes; (3) Add the sieved steel slag into the mixed salt solution, with the mass ratio of metal ions to steel slag being 15%. Ultrasonically impregnate for 3 hours under the conditions of an ultrasonic frequency of 40 kHz and a power of 300 W; (4) Dry the impregnated steel slag at 110 °C for 12 hours; roast the dried material at 800 °C with a microwave power of 850 W for 25 minutes to obtain a cerium-nickel bimetal synergistically modified porous nanostructured steel slag-based oxygen carrier; At the same time, prepare an unmodified steel slag oxygen carrier in the same manner as above, except that an aqueous solution is used to replace the mixed salt solution; (5) Apply the prepared oxygen carrier to the chemical looping gasification of sludge for hydrogen production experiment. Compared with commercially available Fe2O3 and the unmodified steel slag oxygen carrier, the oxygen carrier prepared by the present invention has significant improvements in hydrogen production, the volume fraction of H2 in the syngas, and the activity retention rate after cyclic use, verifying its excellent performance and application prospects. The specific comparison results are as follows: 。 Example 2

[0010] (1) Crush and screen the steel slag to a particle size less than 80 mesh; (2) Weigh cerium nitrate and nickel nitrate in a mass ratio of 1:1, add water to prepare a mixed solution with a concentration of 0.1 mol / L (pH 6), and ultrasonically stir for 40 minutes; (3) Add the screened steel slag to the mixed salt solution, with the mass ratio of metal ions to steel slag being 10%, and ultrasonically impregnate for 2 hours under the conditions of an ultrasonic frequency of 40 kHz and a power of 300 W; (4) Dry the impregnated steel slag at 105 °C for 12 hours; roast the dried material at 850 °C with a microwave power of 800 W for 20 minutes to obtain a cerium-nickel bimetal synergistically modified porous nanostructured steel slag-based oxygen carrier; (5) Performance test: Apply the prepared oxygen carrier to the chemical looping gasification of sludge for hydrogen production experiment. Compared with commercially available Fe2O3 and the unmodified steel slag oxygen carrier (the same as in Example 1), the oxygen carrier prepared by the present invention has significant improvements in hydrogen production, the volume fraction of H2 in the syngas, and the activity retention rate after cyclic use, verifying its excellent performance and application prospects. The specific comparison results are as follows: 。 Example 3

[0011] (1) Crush and screen the steel slag to a particle size less than 80 mesh; (2) Weigh cerium nitrate and nickel nitrate in a mass ratio of 5:1, add water to prepare a mixed solution with a concentration of 0.3 mol / L (pH 6), and ultrasonically stir for 35 minutes; (3) Add the screened steel slag to the mixed salt solution, with the mass ratio of metal ions to steel slag being 20%, and ultrasonically impregnate for 2.5 hours under the conditions of an ultrasonic frequency of 40 kHz and a power of 300 W; (4) Dry the impregnated steel slag at 120 °C for 12 hours; roast the dried material at a microwave power of 900 W and 900 °C for 30 minutes to obtain a cerium-nickel bimetal synergistically modified porous nanostructured steel slag-based oxygen carrier; (5) Performance test: Apply the prepared oxygen carrier to the chemical-looping gasification of sludge for hydrogen production. Compared with commercially available Fe2O3 and unmodified steel slag oxygen carriers (same as in Example 1), the oxygen carrier prepared by the present invention has significantly improved hydrogen production, H2 volume fraction in syngas, and activity retention rate after cyclic use, verifying its excellent performance and application prospects. The specific comparison results are as follows: 。 Example 4

[0012] (1) Crush and screen the steel slag to a particle size less than 80 mesh; (2) Weigh cerium nitrate and nickel nitrate according to a mass ratio of 4:1, mix them, add water to prepare a mixed solution with a concentration of 0.2 mol / L (pH 5), and ultrasonically stir for 35 minutes; (3) Add the screened steel slag to the mixed salt solution, with the mass ratio of metal ions to steel slag being 5%, and ultrasonically impregnate for 2 hours under the conditions of an ultrasonic frequency of 40 kHz and a power of 300 W; (4) Dry the impregnated steel slag at 110 °C for 12 hours; roast the dried material at a microwave power of 850 W and 900 °C for 25 minutes to obtain a cerium-nickel bimetal synergistically modified porous nanostructured steel slag-based oxygen carrier; (5) Performance test: Apply the prepared oxygen carrier to the chemical-looping gasification of sludge for hydrogen production. Compared with commercially available Fe2O3 and unmodified steel slag oxygen carriers (same as in Example 1), the oxygen carrier prepared by the present invention has significantly improved hydrogen production, H2 volume fraction in syngas, and activity retention rate after cyclic use, verifying its excellent performance and application prospects. The specific comparison results are as follows: 。

Claims

1. A preparation method of a cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier, characterized in that: Crush and screen the steel slag to a particle size less than 80 mesh; add the screened steel slag into a mixed solution containing cerium salt and nickel salt, after ultrasonic impregnation for 2 - 3 hours, the impregnated steel slag is dried at 105 - 120 °C, and then calcined at 800 - 900 °C under microwave conditions for 20 - 30 min to obtain a cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier.

2. The preparation method of the cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier according to claim 1, characterized in that: The mass ratio of metal ions to steel slag is 5 - 20%, the metal salt concentration in the mixed solution containing cerium salt and nickel salt is 0.1 - 0.3 mol / L, and the mass ratio of cerium salt to nickel salt is 1:1 - 5:

1.

3. The preparation method of the cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier according to claim 1, characterized in that: The ultrasonic frequency is 40 kHz and the power is 300 W; the microwave power is 800 - 900 W.

4. The preparation method of the cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier according to claim 1, characterized in that: The steel slag is the pressure-heated and simmered steel slag produced by the iron and steel industry.

5. The preparation method of the cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier according to claim 1, characterized in that: The pH value of the mixed solution containing cerium salt and nickel salt is 5 - 7.

6. Application of the cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier prepared by the preparation method of the cerium-nickel bimetal synergistically modified steel slag-based oxygen carrier according to any one of claims 1 - 5 in the process of chemical-looping gasification of sludge for hydrogen production.