An OMS-2 molecular sieve-based combustion-promoting catalyst for coal combustion

Abstract

This invention discloses an OMS-2 molecular sieve-based coal combustion aid catalyst and its preparation method, belonging to the field of catalytic combustion technology for efficient coal utilization. The OMS-2 molecular sieve-based coal combustion aid catalyst is prepared by doping iron and cerium atoms onto an OMS-2 molecular sieve using a one-step redox method. The OMS-2 molecular sieve-based combustion aid catalyst prepared by this invention effectively improves combustion efficiency, reduces the ignition temperature of coal and the activation energy of the reaction, resulting in significant economic benefits and broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of catalytic combustion technology for efficient coal utilization, specifically relating to an OMS-2 molecular sieve-based combustion-promoting catalyst for promoting coal combustion and its preparation method. Background Technology

[0002] Electricity, as a core power source in modern society, continuously drives economic growth and people's livelihoods. For a long time, the coal-fired power supply system has played a pivotal role in ensuring the safety and stability of the power grid. Under the framework of clean energy transition, systematic carbon reduction upgrades have been implemented for existing coal-fired power plants.

[0003] To improve coal utilization efficiency and enhance the economic benefits of related industries, exploration of coal-fired catalysts has been undertaken in fields such as coal-fired power generation and industrial heating since the 19th century. This technology was initially mainly applied to power generation and heating boilers, and in recent years has been gradually extended to the cement industry, achieving large-scale use in production lines with a capacity of 3000–5000 tons / day. Actual operational data shows that the addition of catalysts significantly reduces coal consumption, stabilizes clinker production, improves strength at all stages, increases the rate of free calcium oxide compliance, improves raw meal calcination performance, and lowers the eutectic temperature by approximately 50–100℃. Therefore, the promotion of coal-fired catalysts can bring both economic and environmental benefits to the industry.

[0004] Currently, based on relevant research findings both domestically and internationally, coal-fired catalysts can be categorized into three types: the first type consists of mixed metal salts such as alkali metals, alkaline earth metals, and rare earth metals; the second type comprises metal oxides containing alkali metals, alkaline earth metals, and rare earth metals; and the third type uses organic materials such as low-molecular-weight alcohols or biomass. Among these, the first and second types of catalytic materials have attracted significant attention from researchers in recent years due to their stable physicochemical properties and excellent catalytic activity. Ji Li et al. used thermogravimetric analysis to study the effects of composite catalysts CuSO4 / Fe2(SO4)3, CuSO4 / ZnCl2, Fe2(SO4)3 / ZnCl2, and Fe2(SO4)3 / Zn(NO3)2 on the combustion characteristics of coal char. The results showed that the composite catalysts had good catalytic effects on the combustion of coal char in both anthracite and bituminous coal, with zinc chloride and sulfate showing the best catalytic effects. With the increase of coal metamorphism, the catalytic effect of CuSO4 / Fe2(SO4)3 was significantly enhanced, the decrease in coal char burnout temperature was greater, and the maximum combustion rate was increased. CuSO4 / ZnCl2 and Fe2(SO4)3 / ZnCl2 changed from inhibiting to promoting the ignition of coal char and promoted the burnout of coal char. The apparent activation energy of the coal samples loaded with each catalyst was lower than that of the raw coal char. Gong et al. used thermogravimetric analysis to study the effects of CeO2 and Fe2O3 on the combustion reaction characteristics of several fuels (including tertiary coal, graphite, and anthracite char). The results showed that the addition of CeO2 or Fe2O3 improved the combustion reaction characteristics of all samples except lignite. Although the above studies have confirmed the positive effects of coal-fired catalysts, they still suffer from problems such as easy agglomeration and poor dispersibility, which can lead to a significant decrease in active components and severely restrict the combustion-supporting effect. Therefore, developing novel catalysts that can inhibit the agglomeration of rare earth metal oxides and improve dispersion stability is of great significance for further improving the performance of coal-saving agents. Summary of the Invention

[0005] The purpose of this invention is to provide an OMS-2 molecular sieve-based coal combustion catalyst, in which iron and cerium atoms are simultaneously loaded during the OMS-2 molecular sieve process, thereby effectively improving coal combustion efficiency and reducing the coal ignition temperature and reaction activation energy.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing an OMS-2 molecular sieve-based coal combustion catalyst: iron and cerium atoms are doped onto an OMS-2 molecular sieve by a one-step redox method to obtain the OMS-2 molecular sieve-based coal combustion catalyst.

[0007] Includes the following steps: (1) Dissolve 3g of manganese acetate (Mn(CH3COO)2•4H2O) in 40mL of pure water, add cerium nitrate (Ce(NO3)3•6H2O) and ferric nitrate (Fe(NO3)3•9H2O), stir for 30min to obtain solution A; (2) Dissolve 1.3g of potassium permanganate in 30mL of pure water and stir vigorously at room temperature for 5min to obtain solution B; (3) Slowly add solution B to solution A; after the solution stabilizes, add concentrated nitric acid to adjust the pH of the reaction system; (4) The reaction was carried out at 100℃ for 24 hours, cooled to room temperature, filtered, and repeatedly washed with deionized water until the filtrate was neutral. The mixture was dried at 100℃ for 12 hours, ground, and passed through an 80-mesh sieve to obtain the OMS-2 molecular sieve-based coal combustion catalyst.

[0008] Furthermore, the mass ratio of cerium nitrate, ferric nitrate, and manganese acetate is 1-2:1-2:3.

[0009] Furthermore, in step (3), the pH of the reaction system is adjusted to 0.5-1.0.

[0010] The OMS-2 molecular sieve-based coal combustion catalyst was prepared by the method described above.

[0011] The OMS-2 molecular sieve-based coal combustion catalyst prepared by the method described above is applied to the catalytic combustion reaction of coal.

[0012] The beneficial effects of this invention are as follows: 1. Modified OMS-2 molecular sieve has abundant acidic sites, and the introduction of metal ions Ce and Fe can effectively catalyze the oxidation reaction of volatiles (such as CO, H2 and hydrocarbons) and fixed carbon in coal, reduce the combustion activation energy, and thus promote coal to ignite at a lower temperature and achieve more complete combustion.

[0013] 2. The porous structure of modified OMS-2 molecular sieve has the ability to adsorb and enrich O2, which can form a local high oxygen concentration environment at the combustion interface, accelerate the carbon-oxygen reaction process, and effectively inhibit the generation of incomplete combustion products.

[0014] 3. Modified OMS-2 molecular sieve can disperse coal particles, reduce their agglomeration, and increase the effective contact area between coal and oxygen; at the same time, it maintains a stable porous structure under high temperature conditions, providing a continuous "reaction channel" for the combustion process.

[0015] 4. The entire synthesis process is carried out in a low-temperature environment. The reaction method is simple, easy to operate, and the reaction is rapid. There are no special requirements for the reaction vessel, and it has good process adaptability and scalability. Attached Figure Description

[0016] Figure 1 This is a scanning electron microscope image of the OMS-2 molecular sieve-based coal combustion catalyst prepared in Example 2; Figure 2 Thermogravimetric analysis (TGA) of pulverized coal with OMS-2 molecular sieve-based coal combustion catalyst added in Example 1; Figure 3 Thermogravimetric analysis (TGA) of pulverized coal with OMS-2 molecular sieve-based coal combustion catalyst added in Example 2; Figure 4 Thermogravimetric analysis (TGA) diagram of pulverized coal with OMS-2 molecular sieve-based coal combustion catalyst added in Example 3; Figure 5 Thermogravimetric analysis (TGA) diagram of coal powder without OMS-2 molecular sieve-based coal combustion catalyst, for Comparative Example 1. Detailed Implementation

[0017] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0018] A method for preparing an OMS-2 molecular sieve-based coal combustion catalyst: iron and cerium atoms are doped onto an OMS-2 molecular sieve by a one-step redox method to obtain the OMS-2 molecular sieve-based coal combustion catalyst.

[0019] Includes the following steps: (1) Dissolve 3g of manganese acetate (Mn(CH3COO)2•4H2O) in 40mL of pure water, add cerium nitrate (Ce(NO3)3•6H2O) and ferric nitrate (Fe(NO3)3•9H2O), stir for 30min to obtain solution A; (2) Dissolve 1.3g of potassium permanganate in 30mL of pure water and stir vigorously at room temperature for 5min to obtain solution B; (3) Slowly add solution B to solution A; after the solution stabilizes, add concentrated nitric acid to adjust the pH of the reaction system; (4) The reaction was carried out at 100℃ for 24 hours, cooled to room temperature, filtered, and repeatedly washed with deionized water until the filtrate was neutral. The mixture was dried at 100℃ for 12 hours, ground, and passed through an 80-mesh sieve to obtain the OMS-2 molecular sieve-based coal combustion catalyst.

[0020] Furthermore, the mass ratio of cerium nitrate, ferric nitrate, and manganese acetate is 1-2:1-2:3.

[0021] Furthermore, in step (3), the pH of the reaction system is adjusted to 0.5-1.0.

[0022] Thermogravimetric analysis (TGA) experiments were conducted using a TGA / DSC3+ simultaneous thermal analyzer from METTLER TOLEDO, Switzerland. The test conditions were set as follows: 20 mg of the sample was heated from 25°C to 950°C at a heating rate of 30°C / min under an oxygen atmosphere. The sample mass change as a function of temperature was monitored and recorded in real time during the experiment. Based on the obtained TGA data, key combustion characteristic parameters of the pulverized coal, such as ignition temperature, burnout temperature, ignition index, burnout index, and activation energy, were further analyzed and calculated.

[0023] In Example 1, 3g of manganese acetate tetrahydrate (Mn(CH3COO)2•4H2O) was dissolved in 40mL of pure water, followed by the addition of 1g of cerium nitrate hexahydrate (Ce(NO3)3•6H2O) and 1g of ferric nitrate nonahydrate (Fe(NO3)3•9H2O). The mixture was stirred for 30 minutes to obtain solution A. 1.3g of potassium permanganate was dissolved in 30mL of pure water to obtain solution B. The mixture was stirred vigorously at room temperature for 5 minutes, and then solution B was slowly added dropwise to solution A. After the solution stabilized, concentrated nitric acid was added to adjust the pH of the reaction system to 0.7. After adjustment, the solution was transferred to a 100mL hydrothermal reactor and reacted at 100℃ for 24 hours. After cooling to room temperature, the catalyst was removed, filtered, and repeatedly washed with deionized water until the filtrate was neutral. The filter cake was dried at 100℃ for 12 hours, ground, and passed through an 80-mesh sieve to obtain the OMS-2 molecular sieve-based catalyst material, denoted as Ce / Fe-OMS-2. Finally, 1 g of Ce / Fe-OMS-2 combustion catalyst was mixed with 100 g of pulverized coal to obtain the pulverized coal sample to be tested.

[0024] In Example 2, 3g of manganese acetate tetrahydrate (Mn(CH3COO)2•4H2O) was dissolved in 40mL of pure water, followed by the addition of 1g of cerium nitrate hexahydrate (Ce(NO3)3•6H2O) and 2g of ferric nitrate nonahydrate (Fe(NO3)3•9H2O). The mixture was stirred for 30 minutes to obtain solution A. 1.3g of potassium permanganate was dissolved in 30mL of pure water to obtain solution B. The mixture was stirred vigorously at room temperature for 5 minutes, and then solution B was slowly added dropwise to solution A. After the solution stabilized, concentrated nitric acid was added to adjust the pH of the reaction system to 0.7. After adjustment, the solution was transferred to a 100mL hydrothermal reactor and reacted at 100℃ for 24 hours. After cooling to room temperature, the catalyst was removed, filtered, and repeatedly washed with deionized water until the filtrate was neutral. The filter cake was dried at 100℃ for 12 hours, ground, and passed through an 80-mesh sieve to obtain the OMS-2 molecular sieve-based catalyst material, denoted as Ce / Fe-OMS-2. Finally, 1 g of Ce / Fe-OMS-2 combustion catalyst was mixed with 100 g of pulverized coal to obtain the pulverized coal sample to be tested.

[0025] In Example 3, 3g of manganese acetate tetrahydrate (Mn(CH3COO)2•4H2O) was dissolved in 40mL of pure water, followed by the addition of 2g of cerium nitrate hexahydrate (Ce(NO3)3•6H2O) and 2g of ferric nitrate nonahydrate (Fe(NO3)3•9H2O). The mixture was stirred for 30 minutes to obtain solution A. 1.3g of potassium permanganate was dissolved in 30mL of pure water to obtain solution B. The mixture was stirred vigorously at room temperature for 5 minutes, and then solution B was slowly added dropwise to solution A. After the solution stabilized, concentrated nitric acid was added to adjust the pH of the reaction system to 0.7. After adjustment, the solution was transferred to a 100mL hydrothermal reactor and reacted at 100℃ for 24 hours. After cooling to room temperature, the catalyst was removed, filtered, and repeatedly washed with deionized water until the filtrate was neutral. The filter cake was dried at 100℃ for 12 hours, ground, and passed through an 80-mesh sieve to obtain the OMS-2 molecular sieve-based catalyst material, denoted as Ce / Fe-OMS-2. Finally, 1 g of Ce / Fe-OMS-2 combustion catalyst was mixed with 100 g of pulverized coal to obtain the pulverized coal sample to be tested.

[0026] Comparative Example 1: 100 g of coal powder was taken to obtain the coal powder sample to be tested.

[0027] As can be seen from the data in Table 1, the combustion performance of coal is improved after adding a certain amount of catalyst. In Example 2, when the mass ratio of cerium nitrate hexahydrate, ferric nitrate nonahydrate, and manganese acetate tetrahydrate is 1:2:3, the catalyst can minimize the ignition temperature and activation energy of coal. This is because appropriate iron and cerium doping exposes more acid sites and catalytic sites on the catalyst, allowing it to more effectively attack the weak bonds in coal during combustion, increasing the proportion of reactive carbon atoms, and promoting coal combustion.

[0028] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing an OMS-2 molecular sieve-based coal combustion-promoting catalyst, characterized in that: The OMS-2 molecular sieve-based coal combustion catalyst was prepared by doping iron and cerium atoms onto OMS-2 molecular sieve using a one-step redox method.

2. The method according to claim 1, characterized in that: Includes the following steps: (1) Dissolve 3g of manganese acetate in 40mL of pure water, add cerium nitrate and ferric nitrate, stir for 30min to obtain solution A; (2) Dissolve 1.3g of potassium permanganate in 30mL of pure water and stir vigorously at room temperature for 5min to obtain solution B; (3) Slowly add solution B to solution A; after the solution stabilizes, add concentrated nitric acid to adjust the pH of the reaction system; (4) The reaction was carried out at 100℃ for 24 hours, cooled to room temperature, filtered, and repeatedly washed with deionized water until the filtrate was neutral. The mixture was dried at 100℃ for 12 hours, ground, and passed through an 80-mesh sieve to obtain the OMS-2 molecular sieve-based coal combustion catalyst.

3. The method according to claim 2, characterized in that: The mass ratio of cerium nitrate, ferric nitrate and manganese acetate is 1-2:1-2:

3.

4. The method according to claim 2, characterized in that: In step (3), the pH of the reaction system is adjusted to 0.5-1.

0.

5. An OMS-2 molecular sieve-based coal combustion catalyst prepared by the method according to any one of claims 1-4.

6. An OMS-2 molecular sieve-based coal combustion-promoting catalyst prepared by the method according to any one of claims 1-4, used in coal catalytic combustion reaction, characterized in that: The mass ratio of the OMS-2 molecular sieve-based coal combustion catalyst to pulverized coal is 1:100.

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