A method and apparatus for activation and regeneration of metal sulfide mercury sorbents by hydrogen reduction of lattice sulfur

Abstract

The application adopts hydrogen to react on the surface of metal sulfide to generate a reducing sulfur intermediate, the reducing sulfur intermediate and sulfur dioxide in flue gas occur in-situ reverse disproportionation reaction to generate active sulfur substance for flue gas mercury adsorption, the saturated adsorbent is reduced by hydrogen atmosphere at high temperature to effectively resolve mercury, and the adsorbent activation step is repeated, the surface sulfate of the adsorbent is effectively removed, the poisoning interference of sulfur dioxide in flue gas and the surface sulfate of the adsorbent to the active site is avoided, the mercury adsorbent is regenerated, the mercury adsorption capacity is greatly improved, the energy consumption is reduced, the service life of the adsorbent is improved, the use amount of the adsorbent is reduced, the cost is saved, and the application can be widely applied to the mercury adsorption field.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a method and apparatus for hydrogen reduction of lattice sulfur to activate and regenerate a mercury metal sulfide adsorbent. Background Technology

[0002] Mercury is a toxic element that is persistent, bioaccumulative, highly toxic, and mobile in the atmosphere, posing a significant threat to the ecological environment and human health. Existing wet desulfurization equipment and electrostatic precipitators can effectively remove divalent mercury (Hg). 2+ Mercury and particulate mercury (Hgp), while gaseous zero-valent mercury (Hg) 0 Removing ) is much more difficult.

[0003] Adsorption is the process of removing and recovering Hg from the gaseous environment. 0 The most promising method. Currently used adsorbents include activated carbon, fly ash, metals, and metal oxides. However, traditional mercury adsorbents generally suffer from low adsorption efficiency and low capacity. Metal sulfide adsorbents used in cutting-edge research exhibit excellent adsorption performance, but they also suffer from low capacity and easy deactivation. Furthermore, SO2 and other gases are generated in coal combustion, smelting, and chemical industries and are carried by mercury. 0 When emitted together, SO2 will poison and deactivate most adsorbents, thereby reducing mercury adsorption activity.

[0004] Therefore, a green and environmentally friendly method is needed to solve the sulfate poisoning on the surface of the adsorbent and eliminate the negative impact of SO2 in sulfur-containing flue gas. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned technologies and provide a method and apparatus for activating and regenerating a metal sulfide mercury adsorbent by reducing lattice sulfur with hydrogen. This method is applicable to the activation and regeneration process of the metal sulfide adsorbent in the adsorption and purification of sulfur-containing mercury flue gas.

[0006] Therefore, the present invention provides a method for hydrogen reduction of lattice sulfur to activate and regenerate a mercury metal sulfide adsorbent, characterized by comprising the following steps: (1) Mercury adsorption process: The sulfur-containing mercury flue gas is passed into an adsorption furnace containing a metal sulfide mercury adsorbent, so that the mercury in the flue gas is captured by the metal sulfide mercury adsorbent in the adsorption furnace. (2) Adsorbent regeneration process: The mercury adsorbent saturated with mercury adsorption in step (1) is subjected to high-temperature reduction and regeneration treatment by introducing hydrogen gas to activate the mercury-sulfur bond and realize mercury desorption. (3) Adsorbent reactivation process: Hydrogen and sulfur-containing mercury flue gas are introduced into the metal sulfide mercury adsorbent after mercury desorption in step (2). Hydrogen activates the lattice sulfur sites on the surface of the metal sulfide mercury adsorbent to generate a reducing sulfur intermediate. The reducing sulfur intermediate reacts with sulfur dioxide in the flue gas in an in-situ reverse disproportionation reaction to generate active sulfur substances, thereby activating the surface of the metal sulfide mercury adsorbent and repeating the mercury adsorption process. During the regeneration and reactivation of the adsorbent, hydrogen reacts with the sulfate generated on the surface of the metal sulfide, reducing it to active sulfur substances and reducing sulfur intermediates, effectively removing sulfate from the surface of the adsorbent and preventing poisoning and deactivation of the active sites of the metal sulfide.

[0007] The main reactions involved in the process are as follows: Mercury adsorption process: Active sulfur substances + Hg 0 HgS SO2 + O2 + Metal sulfides sulfates Adsorbent regeneration process: H2+HgS Hg 0 +Reducing sulfur intermediates H2+ metal sulfide lattice sulfur Reducing sulfur intermediate (secondary reaction) H2+ sulfate Reducing sulfur intermediate + reactive sulfur substance + H2O Adsorbent reactivation process: H2+ metal sulfide lattice sulfur Reducing sulfur intermediates Reducing sulfur intermediate + SO2 active sulfur substances H2+ sulfate Reducing sulfur intermediate + reactive sulfur substance + H2O Repeated loop... Preferably, the metal sulfide is a chalcophile or ironophile sulfide.

[0008] Preferably, the metal sulfide is at least one of copper sulfide, zinc sulfide, molybdenum sulfide, and cobalt sulfide.

[0009] Preferably, the hydrogen concentration used in the adsorbent regeneration process is in the range of 10-5000 ppm, and the reaction temperature is 100-600℃.

[0010] Preferably, the hydrogen concentration used in the adsorbent reactivation process is in the range of 10-5000 ppm, and the reaction temperature is 100-600℃.

[0011] An apparatus for implementing the above-described method of hydrogen reduction lattice sulfur activation and regeneration of mercury sulfide adsorbents includes two adsorption furnaces and a six-way valve. The two adsorption furnaces are adsorption furnace I and adsorption furnace II. The six-way valve is provided with inlet valve I, inlet valve II, inlet valve IV, inlet valve V, and outlet valves III and VI. Adsorption furnace I is located on a pipeline connecting outlet valve VI and inlet valve V. A three-way valve VII is also provided on the pipeline between adsorption furnace I and inlet valve V. Adsorption furnace II is located on a pipeline connecting outlet valve III and inlet valve IV. A three-way valve VIII is also provided on the pipeline between adsorption furnace II and inlet valve IV.

[0012] The process route consists of three steps, and two tubular adsorption furnaces are used in conjunction to achieve these three steps, as detailed below: Preferably, during the mercury adsorption process, the inlet valve II is opened to introduce sulfur-containing mercury flue gas, followed by the sequential opening of the outlet valve VI, three-way valve VII, inlet valve V, and outlet valve III. The sulfur-containing mercury flue gas is introduced according to the inlet valve II. Air outlet valve VI Three-way valve VII Intake valve V The flow path of exhaust valve III passes sequentially through adsorption furnace I and adsorption furnace II, allowing the mercury in the flue gas to be captured by the mercury adsorbent in the adsorption furnaces. Three-way valve VII connects the pipeline between adsorption furnace I and inlet valve V.

[0013] Preferably, during the adsorbent regeneration process, hydrogen gas is introduced by opening the inlet valve I and the outlet valve VI is opened to allow hydrogen gas to pass through the adsorption furnace I, thereby increasing the furnace temperature to desorb and regenerate the adsorbent. This process can effectively activate the mercury-sulfur bond and achieve mercury desorption.

[0014] Preferably, during the adsorbent reactivation process, inlet valves I and II are opened to introduce hydrogen and sulfur- and mercury-containing flue gas, while outlet valves VI, VII, V, and III are opened, allowing the airflow to follow the direction of inlet valve II. Air outlet valve VI Three-way valve VII Intake valve V The gas flows through outlet valve III, where hydrogen and sulfur-containing mercury flue gas sequentially pass through adsorption furnace I and adsorption furnace II to perform in-situ reactivation of the adsorbent through reverse disproportionation. In this process, hydrogen effectively activates lattice sulfur and metal-sulfur sites. Furthermore, at high temperatures, hydrogen reacts with sulfates on the adsorbent surface, reducing them to active sulfur substances and reducing sulfur intermediates, thereby removing sulfates and preventing poisoning and deactivation of metal sulfide active sites.

[0015] Both tubular adsorption furnaces in the process route can be used for mercury adsorption, and are mainly controlled by the valve opening and closing sequence of a six-way valve. In the process route of this invention, the mercury adsorption and adsorbent reactivation processes pass through two tubular adsorption furnaces, while the adsorbent regeneration process only passes through the tubular adsorption furnace that needs to be regenerated.

[0016] This invention provides a method and apparatus for activating and regenerating metal sulfide mercury adsorbents based on hydrogen reduction of lattice sulfur, which has the following beneficial effects: (1) By activating the surface of metal sulfides with trace amounts of hydrogen, SO2 in flue gas undergoes an in-situ reverse disproportionation reaction, thereby converting SO2 into active sulfur substances for mercury adsorption, greatly increasing the mercury adsorption capacity and reducing the toxic effects of SO2 in sulfur-containing mercury flue gas. At the same time, the activation with hydrogen will not release toxic and harmful gases.

[0017] (2) During the high-temperature regeneration process, the presence of trace amounts of hydrogen can effectively activate mercury-sulfur bonds and desorb mercury. Hydrogen can also effectively remove sulfates on the surface of the adsorbent, avoid poisoning and deactivation of metal sulfide active sites, continuously form active sites on the surface of the adsorbent, reduce the regeneration temperature, significantly reduce energy consumption, and realize low-temperature mercury desorption and recovery.

[0018] (3) The adsorption efficiency of the activated adsorbent is greatly improved and it can be regenerated and recycled, which greatly improves the service life of the adsorbent and reduces the amount of adsorbent used, thus saving costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow for the hydrogen reduction of lattice sulfur activation and regeneration of the mercury adsorbent for metal sulfides according to the present invention.

[0020] In the diagram: 1. Intake valve I; 2. Intake valve II; 3. Exit valve III; 4. Intake valve IV; 5. Intake valve V; 6. Exit valve VI; 7. Three-way valve VII; 8. Three-way valve VIII. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments to aid in understanding its content. Unless otherwise specified, the methods used in this invention are conventional methods; the raw materials and apparatus used, unless otherwise specified, are conventional commercially available products.

[0022] like Figure 1 As shown, the process route consists of three steps, as detailed below: Mercury adsorption process: Open intake valve II2 to introduce sulfur- and mercury-containing flue gas, then sequentially open outlet valve VI6, three-way valve VII7, intake valve V5, and outlet valve III3. The sulfur- and mercury-containing flue gas is introduced according to the intake valve II2. Air outlet valve VI6 Three-way valve VII7 Intake valve V5 The flow path of the exhaust valve III3 passes sequentially through adsorption furnace I and adsorption furnace II, allowing the mercury in the flue gas to be captured by the mercury adsorbent in the adsorption furnace. Furthermore, the three-way valve VII7 connects the pipeline between adsorption furnace I and the inlet valve V.

[0023] Adsorbent regeneration process: Open the inlet valve I1 to introduce hydrogen gas, and open the outlet valve VI6 to allow the hydrogen gas to pass through adsorption furnace I, raising the furnace temperature to desorb and regenerate the adsorbent.

[0024] Adsorbent reactivation process: Open intake valves I1 and II2 to introduce hydrogen and sulfur- and mercury-containing flue gas. Open exhaust valves VI6, VII7, V5, and III3 to allow airflow according to intake valve II2. Air outlet valve VI6 Three-way valve VII7 Intake valve V5 The gas flows through the outlet valve III3, where hydrogen and sulfur- and mercury-containing flue gas pass sequentially through adsorption furnace I and adsorption furnace II to perform in-situ reactivation of the adsorbent through reverse disproportionation. Example 1

[0025] In the pilot-scale experiment, an alumina-supported copper sulfide adsorbent was first synthesized using alumina (3-5 mm) microspheres as a substrate and copper sulfide as the active adsorbent component via a hydrothermal method. The synthesis amount was 10 kg, and the copper sulfide loading was 10 wt%. The synthesized adsorbent was loaded into two tubular furnaces, with 5 kg of adsorbent loaded into each furnace (Furnace I and Furnace II), and mercury adsorption experiments were conducted. The mercury concentration in the flue gas was 1.2 mg / m³. 3 The SO2 concentration was 3000 ppm, and the oxygen concentration was 5%. The reaction conditions were set at a reaction temperature of 80 degrees Celsius and a space velocity of 80,000 h⁻¹. -1In the mercury adsorption stage, adsorption furnace I and adsorption furnace II are connected in series. The initial mercury adsorption rate of adsorption furnace I is 99.8%, and that of adsorption furnace II is 100%. After 24 hours, the mercury adsorption rate of adsorption furnace I drops to 96.2%, while that of adsorption furnace II remains at 100%. After 168 hours, the mercury adsorption rate of adsorption furnace I is 63.1%, and that of adsorption furnace II is 99.5%. In the adsorbent regeneration stage, to regenerate the adsorbent in adsorption furnace I, the flue gas is shut off, the hydrogen pipeline is opened, and the connection between adsorption furnace I and adsorption furnace II is disconnected. 500 ppm of hydrogen is introduced into adsorption furnace I, and the temperature of adsorption furnace I is raised to 400 degrees Celsius at a rate of 10 degrees Celsius per minute, and maintained at 400 degrees Celsius for 1 hour to regenerate the mercury adsorbent. In the adsorbent reactivation stage, the flue gas pipeline is opened, and adsorption furnace I and adsorption furnace II are reconnected in series, and the temperature of adsorption furnace II is raised to 300 degrees Celsius. Flue gas and 500 ppm hydrogen were introduced into adsorption furnace I for reactivation, which was maintained for 1 hour. The activated adsorbent was then used in repeated mercury adsorption experiments. The results showed that the initial mercury adsorption efficiency in adsorption furnace I was 99.87%, while that in adsorption furnace II was 100%. After 24 hours, the mercury adsorption efficiency in adsorption furnace I was 98.9%, while that in adsorption furnace II remained at 100%. After 168 hours, the mercury adsorption efficiency in adsorption furnace I was 72.3%, and that in adsorption furnace II was 98.2%. This demonstrates that in-situ activation via sulfur reverse disproportionation can effectively improve mercury adsorption efficiency and achieve in-situ regeneration of the mercury adsorbent. Example 2

[0026] Mercury adsorption treatment was performed on waste flue gas from a smelter. First, an alumina-supported zinc sulfide adsorbent was synthesized using a hydrothermal method, with alumina (4-8 mm) microspheres as the substrate and zinc sulfide as the active adsorbent component. The synthesis amount was 20 kg, and the zinc sulfide loading was 15 wt%. The synthesized adsorbent was then loaded into two tubular furnaces, 10 kg each in furnace I and furnace II, for mercury adsorption treatment of the flue gas. The mercury concentration in the sulfur-containing mercury flue gas emitted from the smelter was 0.9 mg / m³. 3 The SO2 concentration was 5000 ppm, and the oxygen concentration was 7%. The reaction conditions were set as follows: tubular furnace reaction temperature 100 degrees Celsius, space velocity 120000 h⁻¹. -1During the adsorption stage, adsorption furnace I and adsorption furnace II were connected in series. The initial mercury adsorption rate of adsorption furnace I was 99.6%, while that of adsorption furnace II was 100%. After 24 hours, the mercury adsorption rate of adsorption furnace I dropped to 96.0%, while that of adsorption furnace II remained at 100%. After 168 hours, the mercury adsorption rate of adsorption furnace I was 62.5%, and that of adsorption furnace II was 99.2%. During the adsorbent regeneration stage, to regenerate the adsorbent in adsorption furnace I, the flue gas was shut off, the hydrogen pipeline was opened, and the connection between adsorption furnace I and adsorption furnace II was disconnected. 800 ppm of hydrogen was introduced into adsorption furnace I, and the temperature of adsorption furnace I was raised to 400 degrees Celsius at a rate of 10 degrees Celsius per minute, maintaining this temperature for 1 hour to regenerate the mercury adsorbent. During the adsorbent reactivation stage, the flue gas pipeline was opened, and adsorption furnace I and adsorption furnace II were reconnected in series, raising the temperature of adsorption furnace II to 350 degrees Celsius. Flue gas and 600 ppm of hydrogen were introduced into adsorption furnace I for reactivation, maintaining the activation time for 1 hour. The above mercury adsorption-regeneration-activation process was repeated three times. After three activation cycles, the adsorbent was tested again for mercury adsorption. The results showed that the initial mercury adsorption efficiency of adsorption furnace I was 97.6%, and that of adsorption furnace II was 100%. After 24 hours, the mercury adsorption efficiency of adsorption furnace I was 98.9%, while that of adsorption furnace II remained at 99.8%. After 168 hours, the mercury adsorption efficiency of adsorption furnace I was 70.6%, and that of adsorption furnace II was 97.2%. This verified that even after three in-situ activations via sulfur reverse disproportionation, the adsorbent's activity only decreased by about 2% with repeated use.

[0027] In summary, this invention provides suitable reaction conditions in a tubular adsorption furnace, allowing hydrogen to react on the surface of metal sulfides to generate a reducing sulfur intermediate. This intermediate then undergoes an in-situ reverse disproportionation reaction with sulfur dioxide in the flue gas to generate active sulfur substances for mercury adsorption. The saturated adsorbent is then reduced at high temperature in a hydrogen atmosphere to effectively remove mercury. The adsorbent activation step is repeated to effectively remove sulfates from the adsorbent surface, avoiding the toxic interference of sulfur dioxide in the flue gas and sulfates on the adsorbent surface to the active sites, thus regenerating the mercury adsorbent. The sulfur-containing mercury flue gas adsorbed by this device fully meets national mercury emission requirements. After adsorption, the sulfur and mercury resources can be recycled to obtain additional economic value. Furthermore, the used adsorbent can be regenerated and reused by removing sulfates and generating new active sulfur sites through surface activation.

[0028] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for activating and regenerating a mercury metal sulfide adsorbent by reducing lattice sulfur with hydrogen, characterized in that, Includes the following steps: (1) Mercury adsorption process: The sulfur-containing mercury flue gas is passed into an adsorption furnace containing a metal sulfide mercury adsorbent, so that the mercury in the flue gas is captured by the metal sulfide mercury adsorbent in the adsorption furnace. (2) Adsorbent regeneration process: The mercury adsorbent saturated with mercury adsorption in step (1) is subjected to high-temperature reduction and regeneration treatment by introducing hydrogen gas to activate the mercury-sulfur bond and realize mercury desorption. The hydrogen concentration used in the adsorbent regeneration process is in the range of 500-800 ppm, and the reaction temperature is 400-600℃. (3) Adsorbent reactivation process: Hydrogen and sulfur-containing mercury flue gas are introduced into the metal sulfide mercury adsorbent after mercury desorption in step (2). Hydrogen activates the lattice sulfur sites on the surface of the metal sulfide mercury adsorbent to generate a reducing sulfur intermediate. The reducing sulfur intermediate reacts with sulfur dioxide in the flue gas in an in-situ reverse disproportionation reaction to generate active sulfur substances, thereby activating the surface of the metal sulfide mercury adsorbent and repeating the mercury adsorption process. The hydrogen concentration used in the adsorbent reactivation process is in the range of 500-600 ppm, and the reaction temperature is 300-600℃. During the regeneration and reactivation of the adsorbent, hydrogen reacts with the sulfate generated on the surface of the metal sulfide, reducing it to active sulfur substances and reducing sulfur intermediates, effectively removing sulfate from the surface of the adsorbent and avoiding poisoning of the active sites of the metal sulfide.

2. The method for hydrogen reduction of lattice sulfur to activate and regenerate a mercury sulfide adsorbent according to claim 1, characterized in that, The metal sulfide is a chalcophile or ironophile sulfide.

3. The method for hydrogen reduction of lattice sulfur to activate and regenerate a mercury sulfide adsorbent according to claim 2, characterized in that, The metal sulfide is at least one of copper sulfide, zinc sulfide, molybdenum sulfide, and cobalt sulfide.

4. An apparatus for implementing the method of hydrogen reduction lattice sulfur activation and regeneration of a metal sulfide mercury adsorbent according to any one of claims 1-3, characterized in that, The equipment includes two adsorption furnaces and a six-way valve. The two adsorption furnaces are adsorption furnace I and adsorption furnace II. The six-way valve is equipped with inlet valve I, inlet valve II, inlet valve IV, inlet valve V, and outlet valve III and outlet valve VI. Adsorption furnace I is located on the pipeline connecting outlet valve VI and inlet valve V. A three-way valve VII is also provided on the pipeline between adsorption furnace I and inlet valve V. Adsorption furnace II is located on the pipeline connecting outlet valve III and inlet valve IV. A three-way valve VIII is also provided on the pipeline between adsorption furnace II and inlet valve IV.

5. The apparatus for implementing the method of hydrogen reduction of lattice sulfur activation and regeneration of metal sulfide mercury adsorbent according to claim 4, characterized in that, During the mercury adsorption process, inlet valve II is opened to introduce sulfur-containing mercury flue gas. Then, outlet valve VI, three-way valve VII, inlet valve V, and outlet valve III are opened sequentially. The sulfur-containing mercury flue gas is introduced according to the inlet valve II. Air outlet valve VI Three-way valve VII Intake valve V The gas flows through the outlet valve III, passing sequentially through adsorption furnace I and adsorption furnace II, so that the mercury in the flue gas is captured by the mercury adsorbent in the adsorption furnace.

6. The apparatus for implementing the method of hydrogen reduction of lattice sulfur activation and regeneration of metal sulfide mercury adsorbent according to claim 4, characterized in that, During the adsorbent regeneration process, hydrogen gas is introduced by opening the inlet valve I and the outlet valve VI is opened to allow hydrogen gas to pass through the adsorption furnace I, thereby increasing the furnace temperature and desorbing and regenerating the adsorbent.

7. The apparatus for implementing the method of hydrogen reduction of lattice sulfur activation and regeneration of metal sulfide mercury adsorbent according to claim 4, characterized in that, During the adsorbent reactivation process, inlet valves I and II are opened to introduce hydrogen and sulfur-containing mercury flue gas. Outlet valves VI, VII, V, and III are also opened to allow airflow to follow the flow pattern specified by inlet valve II. Air outlet valve VI Three-way valve VII Intake valve V The gas flows through the outlet valve III, where hydrogen and sulfur- and mercury-containing flue gas pass sequentially through adsorption furnace I and adsorption furnace II to perform in-situ reactivation of the adsorbent through reverse disproportionation.

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