A nitrogen-doped petroleum coke-based activated carbon catalyst for catalytic oxidation of H2S at room temperature, and its preparation method and application

Abstract

The present invention discloses a nitrogen-doped petroleum coke-based activated carbon catalyst for catalytic oxidation of H2S at room temperature, as well as its preparation method and application. The method comprises: (1) first grinding and sieving lump petroleum coke to obtain petroleum coke powder; (2) then thoroughly mixing the petroleum coke powder with an activator, activating the mixture at high temperature, cooling the mixture, washing, and drying the mixture to obtain activated activated carbon; (3) finally grinding and mixing the activated activated carbon with melamine OAT waste residue, and calcining the mixture at high temperature to obtain nitrogen-doped petroleum coke-based activated carbon. The method first utilizes nitrogen atoms embedded in the carbon skeleton to increase the Lewis alkalinity and power supply capacity of the material surface, thereby improving the ability to ionize H2S and absorb O2. Simultaneously, the large specific surface area and well-developed pores of the activated carbon are utilized to effectively store H2S catalytic oxidation products, thereby improving the reactive ability of the activated carbon to catalytically oxidize H2S.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen sulfide purification, and in particular to a preparation method and application of a nitrogen-doped petroleum coke-based activated carbon material for catalytic oxidation of hydrogen sulfide (H2S) at room temperature. Background Art

[0002] H2S is one of the main components of malodorous gases. It has a low odor threshold and is highly toxic, causing human poisoning or death. In addition, its strong corrosiveness can cause hydrogen embrittlement and fracture in metal pipes and equipment, causing great harm. It is essential to treat H2S through appropriate methods and materials.

[0003] H2S is widely present in municipal wastewater, petrochemicals, natural gas plants, and other industrial processes. Treatment methods typically include absorption, adsorption, biological, and oxidation for waste gases with varying emission characteristics. Absorption, which absorbs H2S using liquid adsorbents, is highly efficient but produces large amounts of wastewater and carries high treatment costs. Adsorption is suitable for low-temperature, high-concentration waste gases, but current adsorbent materials have low sulfur capacity, short adsorbent replacement cycles, and high operating costs. Biological methods are often used to treat H2S in municipal wastewater, but are prone to problems such as decreased purification efficiency and increasing acidity. Oxidation, which oxidizes H2S to elemental sulfur or sulfur oxides, offers excellent treatment results and allows for its reuse. The Claus process is one of the most widely used oxidation methods, but due to thermodynamic equilibrium, it cannot completely remove H2S from exhaust gases.

[0004] Porous activated carbon catalytically oxidizes H2S, effectively treating it at room temperature and relatively low temperatures (below 230°C). Unaffected by thermodynamic equilibrium, it can thoroughly purify H2S. This material has a wide range of applications, simple application methods, excellent purification effects, and high efficiency, making it a highly promising H2S purification material.

[0005] In the industrial application of this material, improving sulfur capacity and controlling and reducing costs are the key. A large number of studies have shown that by doping activated carbon materials with nitrogen, the local Lewis alkalinity and power supply capacity of the material surface can be improved, thereby promoting the ionization of H2S and the adsorption of O2, thereby improving the catalytic performance and sulfur capacity of the activated carbon material [CHEN L, YUAN J, LI T, et al. Aregeneric N-rich hierarchical porous carbon synthesized from waste biomass for H2S removal at room temperature [J]. Sci Total Environ, 2021, 768: 144452; LIJ, YIN S, DONG F, et al. Tailoring Active Sites via Synergy between Graphitic and Pyridinic N for Enhanced Catalytic Efficiency of a Carbocatalyst [J]. Acs Applied Materials & Interfaces, 2017, 9 (23): 19861-9.]. Currently, researchers have studied the preparation of desulfurization nitrogen-doped activated carbon materials, but most preparation methods have problems such as complex processes, expensive materials, high preparation costs, and poor performance of the resulting materials, making it difficult to achieve commercial promotion. Long Donghui et al. used phenol, melamine, and formaldehyde as carbon precursors and used a silica sol-gel method to prepare nitrogen-doped activated carbon. This method accurately controls the pore size of the activated carbon, and the material has the best reported sulfur penetration capacity (2.77 g / g). However, its complex preparation process is not conducive to promotion and application [SUN FG, LIUJ, CHEN HC, et al. Nitrogen-Rich Mesoporous Carbons: Highly Efficient, Regenerative Metal-Free Catalysts for Low-Temperature Oxidation of H2S[J]. Acs Catalysis, 2013, 3(5): 862-70.].Jiang Xia et al. used waste polyurethane (PU) as raw material and prepared nitrogen-doped desulfurized activated carbon by simple activated carbonization, realizing waste utilization, but its penetration sulfur capacity was only (205 mg / g) and the material performance was poor [CHEN W, ZHANGG, LI D, et al. Preparation of Nitrogen-Doped Porous Carbon from Waste Polyurethane Foam by Hydrothermal Carbonization for H2S Adsorption[J]. Industrial & Engineering Chemistry Research, 2020, 59(16): 7447-56.]. Therefore, it is urgent to develop a high-efficiency and low-cost desulfurized nitrogen-doped activated carbon. Petroleum coke is a low-value by-product of petroleum refining, and its high carbon content can be used to prepare activated carbon; melamine OAT waste residue is a by-product produced in the high-pressure melamine production process. Its main components include melamine, ammeline, ammeline, etc., and its nitrogen content is high, which is suitable for use as a nitrogen-doped raw material. Using the above two low-value materials as raw materials can greatly reduce the preparation cost of activated carbon.

[0006] In light of this, the present invention proposes a method for preparing a nitrogen-doped petroleum coke-based activated carbon catalyst for the ambient-temperature catalytic oxidation of H2S using petroleum coke and melamine OAT waste as raw materials. Compared to other raw materials (chemical raw materials, biomass, etc.), this method significantly simplifies the preparation process and reduces costs, while demonstrating excellent ambient-temperature catalytic H2S oxidation performance. By selecting appropriate raw materials and an appropriate preparation method, this method combines low-value material utilization, low preparation costs, and high catalytic performance, demonstrating significant practical value. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of existing catalysts such as high preparation cost and low sulfur capacity, and provide a method for preparing nitrogen-doped activated carbon using low-value materials such as petroleum coke and melamine OAT waste residue as raw materials. The prepared activated carbon has excellent performance in catalytic oxidation and purification of H2S at room temperature.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing a nitrogen-doped petroleum coke-based activated carbon catalyst for catalytic oxidation of H2S at room temperature comprises the following steps: first preparing a petroleum coke-based activated carbon activated by potassium hydroxide, and then calcining the activated carbon with melamine OAT waste residue at high temperature to obtain a nitrogen-doped petroleum coke-based activated carbon catalyst; the method first utilizes nitrogen atoms embedded in a carbon skeleton to enhance the Lewis alkalinity and power supply capacity of the material surface, thereby enhancing the ability to ionize H2S and absorb O2; and simultaneously utilizes the large specific surface area and developed pores of the activated carbon to effectively store H2S catalytic oxidation products, thereby enhancing the reactivity of the activated carbon in catalytic oxidation of H2S.

[0010] The preparation method comprises:

[0011] (1) Grinding and sieving lump petroleum coke to obtain petroleum coke powder;

[0012] (2) fully mixing petroleum coke powder and an activator, activating them at high temperature, cooling them, washing them, and drying them to obtain activated carbon;

[0013] (3) Grind and mix the activated carbon and melamine OAT waste residue, and calcine at high temperature to obtain nitrogen-doped petroleum coke-based activated carbon.

[0014] In the above method, in step (1), the petroleum coke is delayed coke; and the petroleum coke powder particles are 100-200 meshes.

[0015] In the above method, in step (2), the activator is one or more of potassium hydroxide, sodium hydroxide, and sodium bicarbonate, preferably potassium hydroxide.

[0016] In the above method, in step (2), the mass ratio of the activator to the petroleum coke powder is 1 to 3:1, preferably 1.5 to 2:1.

[0017] In the above method, in step (2), the high-temperature activation temperature is 750-800°C; the heating rate is 5-10°C / min; the activation time is 1-2h; the activation atmosphere is nitrogen; and the nitrogen flow rate is 50-100ml / min.

[0018] In the above method, in step (2), the washing liquid is deionized water; the drying temperature is 80 to 105° C.; and the drying time is 8 to 24 hours.

[0019] In the above method, in step (3), the mass ratio of the melamine OAT waste residue to the activated petroleum coke-based activated carbon is 0.5 to 2:1, preferably 0.75 to 1:1.

[0020] In the above method, in step (3), the high-temperature calcination temperature is 500-900°C; the heating rate is 5-10°C / min; the activation time is 1-2h; the activation atmosphere is nitrogen; and the nitrogen flow rate is 50-100ml / min.

[0021] A nitrogen-doped petroleum coke-based activated carbon material for catalytic oxidation of H2S at room temperature, wherein the petroleum coke-based activated carbon has a specific surface area of ​​834 to 1347 mg / g and a pore volume of 0.35 to 0.57 cm 3 / g; space velocity is 17500h -1 The maximum penetration sulfur capacity is 458 mg / g.

[0022] The application of the nitrogen-doped petroleum coke-based activated carbon catalyst in the catalytic oxidation of hydrogen sulfide at room temperature.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. In the preparation method of the desulfurization activated carbon material of the present invention, petroleum coke and melamine OAT waste residue are used as raw materials, and high-value materials are prepared from low-value raw materials, which can greatly reduce the preparation cost of the desulfurization activated carbon material.

[0025] 2. The present invention's method for preparing desulfurization activated carbon material utilizes a two-step process to achieve activation, pore formation, and nitrogen doping control. This method is simple and easy to operate, with controllable nitrogen doping configurations, making it suitable for large-scale production.

[0026] 3. In the preparation method of the desulfurization activated carbon material of the present invention, the amount of the alkali activator used is relatively low, which reduces production costs and reduces equipment corrosion and environmental pollution problems.

[0027] 4. The desulfurization activated carbon material of the present invention has a space velocity of 17500h at room temperature (25°C). -1 The maximum penetration sulfur capacity can reach 458 mg / g, and it has good hydrogen sulfide removal ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The H2S penetration curves of the activated carbon materials of Examples 1 to 5 of the present invention are shown. (Activated carbon 150 mg, quartz sand 300 mg, gas flow rate 135 ml / min, space velocity 17500 h -1 , H2S concentration 1000ppm, humidity ~60%);

[0029] Figure 2 N2 adsorption and desorption curves of the activated carbon materials of Examples 1 to 5 of the present invention;

[0030] Figure 3 This is the DFT pore size distribution diagram of the activated carbon materials of Examples 1 to 5 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be described in further detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto.

[0032] Example 1

[0033] (1) Grind the lump petroleum coke and sieve to obtain 100-200 mesh petroleum coke powder.

[0034] (2) Petroleum coke powder and potassium hydroxide were mixed in a mass ratio of 1:2 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and activated at 800°C for 1 h at a heating rate of 5°C / min under a nitrogen atmosphere of 100 ml / min. After cooling, the mixture was washed with deionized water until neutral, filtered, and the obtained solid sample was placed in an oven and dried at 105°C for 12 h to obtain activated petroleum coke-based activated carbon.

[0035] (3) Activated petroleum coke-based activated carbon and melamine OAT waste residue were mixed in a mass ratio of 1:0.75 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and calcined at 800°C for 2 h at a heating rate of 5°C / min in a nitrogen atmosphere of 100 ml / min. After cooling, the product petroleum coke-based nitrogen-doped activated carbon was obtained, which was designated as NPC-2-0.75(800).

[0036] Example 2

[0037] (1) Grind the lump petroleum coke and sieve to obtain 100-200 mesh petroleum coke powder.

[0038] (2) Petroleum coke powder and potassium hydroxide were mixed in a mass ratio of 1:2 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and activated at 800°C for 1 h at a heating rate of 5°C / min under a nitrogen atmosphere of 100 ml / min. After cooling, the mixture was washed with deionized water until neutral, filtered, and the obtained solid sample was placed in an oven and dried at 105°C for 12 h to obtain activated petroleum coke-based activated carbon.

[0039] (3) Activated petroleum coke-based activated carbon and melamine OAT waste residue were mixed in a mass ratio of 1:1 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and calcined at 800°C for 2 h at a heating rate of 5°C / min in a nitrogen atmosphere of 100 ml / min. After cooling, the product petroleum coke-based nitrogen-doped activated carbon was obtained, which was designated as NPC-2-1(800).

[0040] Example 3

[0041] (1) Grind the lump petroleum coke and sieve to obtain 100-200 mesh petroleum coke powder.

[0042] (2) Petroleum coke powder and potassium hydroxide were mixed in a mass ratio of 1:1.5 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and activated at 800°C for 1 h at a heating rate of 5°C / min under a nitrogen atmosphere of 100 ml / min. After cooling, the mixture was washed with deionized water until neutral, filtered, and the obtained solid sample was placed in an oven and dried at 105°C for 12 h to obtain activated petroleum coke-based activated carbon.

[0043] (3) Activated petroleum coke-based activated carbon and melamine OAT waste residue were mixed in a mass ratio of 1:1 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and calcined at 800°C for 2 h at a heating rate of 5°C / min in a nitrogen atmosphere of 100 ml / min. After cooling, the product petroleum coke-based nitrogen-doped activated carbon was obtained, which was designated as NPC-1.5-1(800).

[0044] Example 4

[0045] (1) Grind the lump petroleum coke and sieve to obtain 100-200 mesh petroleum coke powder.

[0046] (2) Petroleum coke powder and potassium hydroxide were mixed in a mass ratio of 1:2 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and activated at 800°C for 1 h at a heating rate of 5°C / min under a nitrogen atmosphere of 100 ml / min. After cooling, the mixture was washed with deionized water until neutral, filtered, and the obtained solid sample was placed in an oven and dried at 105°C for 12 h to obtain activated petroleum coke-based activated carbon.

[0047] (3) Activated petroleum coke-based activated carbon and melamine OAT waste residue were mixed in a mass ratio of 1:1 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and calcined at 700°C for 2 h at a heating rate of 5°C / min under a 100 ml / min nitrogen atmosphere. After cooling, the product petroleum coke-based nitrogen-doped activated carbon was obtained, which was designated as NPC-2-1(700).

[0048] Example 5

[0049] (1) Grind the lump petroleum coke and sieve to obtain 100-200 mesh petroleum coke powder.

[0050] (2) Petroleum coke powder and potassium hydroxide were mixed in a mass ratio of 1:2 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and activated at 800°C for 1 h at a heating rate of 5°C / min under a nitrogen atmosphere of 100 ml / min. After cooling, the mixture was washed with deionized water until neutral, filtered, and the obtained solid sample was placed in an oven and dried at 105°C for 12 h to obtain activated petroleum coke-based activated carbon.

[0051] (3) Activated petroleum coke-based activated carbon was ground for 10 min to obtain activated carbon powder. The activated carbon powder was placed in a tube furnace and calcined at 800°C for 2 h at a heating rate of 5°C / min under a 100 ml / min nitrogen atmosphere. After cooling, the product petroleum coke-based activated carbon was obtained, which was designated as PC-2(800).

[0052] H2S room temperature catalytic oxidation method: 150mg of 100-200 mesh catalyst and 300mg of quartz sand were fully mixed and loaded into a quartz tube with an outer diameter of 8nm and an inner diameter of 6nm. During the experiment, a mixed gas containing H2S was introduced for reaction (H2S concentration was 1000ppm, dry air balance, flow rate was 135ml / min, space velocity was 17500h -1 , reaction temperature 25°C, relative humidity RH ~ 60%). The H2S concentration at the reactor outlet was detected by a portable H2S detector.

[0053] Figure 1 This is the penetration curve of the activated carbon material described in Examples 1-5 of the present invention. The test conditions are: 150 mg of activated carbon, 300 mg of quartz sand, gas flow rate of 135 ml / min, and space velocity of 17500 h -1 , H2S concentration 1000ppm, humidity ~60%. Table 1 shows the sulfur penetration capacity of the activated carbon materials described in Examples 1-5 of the present invention. Figure 1 As shown in Table 1, the material described in Example 1 has the highest breakthrough sulfur capacity, which is 458 mg / g.

[0054] Figure 2 The N2 adsorption and desorption curves of the activated carbon materials described in Examples 1-5 of the present invention are shown in FIG. Figure 2 As shown in the figure, the N2 adsorption-desorption curves of all materials have the characteristics of type I adsorption-desorption curves.

[0055] Figure 3 This is the DFT pore size distribution diagram of the activated carbon material described in Examples 1-5 of the present invention. Figure 3 As shown, the pore size of all materials is mainly micropores less than 2 mm, with the smallest pore size being 0.6-0.7 mm, and having a good microporous structure.

[0056] Table 2 shows the BET specific surface area and pore volume of the activated carbon materials described in Examples 1 to 5 of the present invention. As shown in Table 2, the materials are mainly microporous structures, with a micropore ratio of up to 86%.

[0057] Table 1 H2S breakthrough sulfur capacity of activated carbon materials of Examples 1 to 5 of the present invention

[0058]

[0059] Table 2 shows the BET specific surface area and pore volume of the activated carbon materials of Examples 1 to 5 of the present invention.

[0060]

Claims

1. Application of a nitrogen-doped petroleum coke-based activated carbon catalyst in the catalytic oxidation of hydrogen sulfide at room temperature, characterized in that: The preparation method of the nitrogen-doped petroleum coke-based activated carbon catalyst comprises: (1) Grinding and sieving lump petroleum coke to obtain 100-200 mesh petroleum coke powder; (2) Petroleum coke powder and potassium hydroxide were mixed in a mass ratio of 1:2 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and activated at 800°C for 1 h at a heating rate of 5°C / min under a nitrogen atmosphere of 100 mL / min. After cooling, it was washed with deionized water until neutral and filtered. The obtained solid sample was placed in an oven and dried at 105°C for 12 h to obtain activated petroleum coke-based activated carbon. (3) Activated petroleum coke-based activated carbon and melamine OAT waste residue were mixed in a mass ratio of 1:0.75 and ground for 10 min to obtain a mixed powder. The mixed powder was placed in a tube furnace and calcined at 800°C for 2 h at a heating rate of 5°C / min under a nitrogen atmosphere of 100 mL / min. After cooling, the product nitrogen-doped petroleum coke-based activated carbon was obtained. The air space velocity was 17500 h -1 The breakthrough sulfur capacity of nitrogen-doped petroleum coke-based activated carbon is 458 mg / g.

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