A method for producing hydrogen gas using a sulfuric acid residue

Abstract

The application relates to a method for preparing hydrogen gas by using sulfuric acid residue, which comprises the following steps: chemically reacting a first mixed gas with sulfuric acid residue to obtain ferrous sulfate and a second mixed gas; wherein the first mixed gas comprises hydrogen sulfide gas, water vapor and oxygen; cooling the second mixed gas and then separating the second mixed gas to obtain hydrogen gas. The application solves the technical problem that the existing sulfuric acid residue is difficult to effectively utilize.

Description

Technical Field

[0001] This application relates to the field of solid waste recycling technology, and in particular to a method for preparing hydrogen from sulfuric acid residue. Background Technology

[0002] Sulfuric acid slag is the waste residue from the production of sulfuric acid in the pyrite industry. Large-scale stockpiling of this waste occupies land and easily causes pollution. The main components of sulfuric acid slag are Fe₂O₃ (55-60%), SiO₂ (6-8%), and CaO, MgO, and Al. l2 The O3 content is less than 3%, and the S content is less than 1%.

[0003] During the coking process, approximately 30% to 35% of the sulfur in coal is converted into hydrogen sulfide and other sulfides, which enter the coal gas and form gaseous impurities. Hydrogen sulfide is highly corrosive and toxic. In subsequent coal gas production processes, it causes severe corrosion to production equipment and pipelines, leading to poisoning and deactivation of the syngas chemical reaction catalyst, seriously affecting the yield and quality of the final product, and polluting the environment. Summary of the Invention

[0004] This application provides a method for preparing hydrogen from sulfuric acid residue, thereby solving the technical problem that existing sulfuric acid residue is difficult to utilize effectively.

[0005] In a first aspect, this application provides a method for preparing hydrogen from sulfuric acid residue, the method comprising:

[0006] The first mixed gas is chemically reacted with sulfuric acid residue to obtain ferrous sulfate and a second mixed gas; wherein the first mixed gas includes hydrogen sulfide gas, water vapor and oxygen;

[0007] The second mixed gas is cooled and then separated to obtain hydrogen.

[0008] Optionally, the particle size of the sulfuric acid residue is 20-200 mesh.

[0009] Optionally, the molar ratio of the hydrogen sulfide gas, the water vapor, and the oxygen is (10-50):(30-40):(5-10).

[0010] Optionally, the temperature of the chemical reaction is 443–500 K.

[0011] Optionally, the temperature of the chemical reaction is 473K.

[0012] Optionally, the step of cooling and then separating the second mixed gas to obtain hydrogen includes:

[0013] The second mixed gas was cooled and then separated using an alkali metal carbonate solution to obtain hydrogen.

[0014] Optionally, the second mixed gas is 10 to 100 parts by volume relative to 1 part by volume of the alkali metal carbonate solution.

[0015] Optionally, the flow rate of the hydrogen sulfide gas is ≥0.1L / min.

[0016] Optionally, the oxygen flow rate is ≤0.05L / min.

[0017] The technical solutions provided in this application have the following advantages compared with the prior art:

[0018] The method for preparing hydrogen from sulfuric acid slag provided in this application involves passing hydrogen sulfide, water vapor, and oxygen through sulfuric acid slag to obtain ferrous sulfate and hydrogen. This method comprehensively utilizes sulfuric acid slag and hydrogen sulfide, which are difficult to use in industry. It reduces the amount of solid waste and obtains new raw materials, ferrous sulfate and hydrogen, which can create objective economic value and find a new direction for hydrogen production. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart of a method for preparing hydrogen from sulfuric acid residue, provided as an embodiment of this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0024] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0026] Firstly, this application provides a method for preparing hydrogen from sulfuric acid residue; please refer to [link to relevant documentation]. Figure 1 The method includes:

[0027] S1. The first mixed gas is chemically reacted with sulfuric acid residue to obtain ferrous sulfate and a second mixed gas; wherein, the first mixed gas includes hydrogen sulfide gas, water vapor and oxygen;

[0028] In some embodiments, the particle size of the sulfuric acid residue is 20 to 200 mesh.

[0029] In this embodiment, the particle size of the sulfuric acid slag is controlled to ensure the smooth progress of subsequent chemical reactions. If the particle size is too large, the reaction contact surface of the sulfuric acid slag is small during the above chemical reaction, making it difficult to contact the center of the sulfuric acid slag particles, resulting in incomplete reactions. If the particle size is too small, the reactants are easily blown out of the experimental tube during aeration, which may cause experimental deviations. Specifically, the particle size of the sulfuric acid slag can be 20 mesh, 40 mesh, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh, 200 mesh, etc.

[0030] In some embodiments, the molar ratio of the hydrogen sulfide gas, the water vapor, and the oxygen is (10-50):(30-40):(5-10).

[0031] In this embodiment, the molar ratio of hydrogen sulfide gas, water vapor, and oxygen is controlled, with hydrogen sulfide in excess in the reactants to minimize oxygen in the product mixture. The excess hydrogen sulfide is then absorbed by the alkali metal carbonate, yielding relatively pure hydrogen. Excessive hydrogen sulfide in the reactants leads to waste of the alkali metal carbonate and increased costs. Insufficient hydrogen sulfide reduces the reaction rate and prolongs the reaction time, resulting in energy waste. Excessive water vapor reduces reactant concentration, slowing the reaction rate and prolonging the reaction time, also wasting energy. Insufficient water vapor increases reactant concentration, causing the reaction to proceed too quickly and potentially leading to accidents. Excessive oxygen increases reactant concentration, causing the reaction to proceed too quickly and making the experiment difficult to control. Insufficient oxygen reduces reactant concentration, slowing the reaction rate and prolonging the reaction time, also wasting energy. Specifically, the molar ratio of hydrogen sulfide gas, water vapor, and oxygen can be 2:6:1, 5:4:1, 5:4:1, 40:35:7, 5:9:2, etc.

[0032] In some embodiments, the temperature of the chemical reaction is 443–500 K.

[0033] In some embodiments, the temperature of the chemical reaction is 473 K.

[0034] In the embodiments of this application, the reaction equation for the above chemical reaction is Fe2O3 + 2H2S + 3O2 → 2FeSO4 + H2O +

[0035] H2 is used to control the temperature of the chemical reaction, making the reaction controllable. If the temperature is too high, there will be too many side reactions and the products will be uncontrollable; if the temperature is too low, the reaction will be difficult to proceed. Specifically, the temperature of this chemical reaction can be 443K, 445K, 450K, 455K, 460K, 470K, 480K, 490K, 500K, etc., preferably 473K. Furthermore, ferrous sulfate is subsequently dissolved in water, filtered, and evaporated to obtain pure ferrous sulfate crystals.

[0036] S2. The second mixed gas is cooled and then separated to obtain hydrogen.

[0037] In some embodiments, cooling and then separating the second mixed gas to obtain hydrogen includes:

[0038] The second mixed gas was cooled and then separated using an alkali metal carbonate solution to obtain hydrogen.

[0039] In this embodiment, hydrogen sulfide is removed using an alkali metal carbonate desulfurization process, specifically a vacuum carbonation desulfurization process. This process offers advantages such as high product purity and quality, full utilization of waste heat, no secondary pollution, good environmental protection, and reliable and stable system operation. The alkali metal carbonate can be potassium carbonate or sodium carbonate.

[0040] In some embodiments, the second mixed gas is 10 to 100 parts by volume relative to 1 part by volume of the alkali metal carbonate solution.

[0041] In this embodiment, the amount of alkali metal carbonate solution is controlled to reduce the amount of absorbent during the recovery of hydrogen sulfide in the later stages of the experiment, thereby improving the recovery rate of hydrogen sulfide. Specifically, relative to 1 volume part of alkali metal carbonate solution, the second mixed gas is 10 volume parts, 20 volume parts, 30 volume parts, 40 volume parts, 50 volume parts, 60 volume parts, 70 volume parts, 80 volume parts, 90 volume parts, or 100 volume parts.

[0042] In some embodiments, the flow rate of the hydrogen sulfide gas is ≥0.1 L / min.

[0043] In some embodiments, the oxygen flow rate is ≤0.05 L / min.

[0044] In this embodiment, the flow rate of hydrogen sulfide gas is controlled to ensure a stable reaction. Specifically, the flow rate of the hydrogen sulfide gas can be 0.1 L / min, 0.15 L / min, 0.2 L / min, 0.25 L / min, etc. The flow rate of oxygen is controlled to reduce reaction risk and obtain purer hydrogen gas as a reactant. Specifically, the flow rate of oxygen can be 0.05 L / min, 0.045 L / min, 0.04 L / min, etc.

[0045] For a detailed description of the method for producing hydrogen from sulfuric acid residue, please refer to the following:

[0046] I. Preparation and connection of the test system:

[0047] 1. Gas preparation: Connect the hydrogen sulfide cylinder and gas flow meter and input it into the sealed water tank. Connect the oxygen cylinder to the gas flow meter. After checking the airtightness of the gas system, connect it to the gas inlet pipe.

[0048] 2. Preparation of sulfuric acid residue: Dry 5 grams of the obtained sulfuric acid residue, grind it into a fine powder using a mortar and pestle, weigh 5 grams of the prepared sulfuric acid residue and place it into a quartz tube. Seal both ends of the quartz tube with short quartz fibers, place the quartz tube into the heating furnace, and connect the glass gas supply pipe. Check the airtightness of the quartz tube system.

[0049] 3. Preparation of the gas receiving system: Collect the test hydrogen gas using the air displacement method, connect the gas tank to the gas flow meter, then connect the gas flow meter to the collection bottle containing water, and finally connect it to the collection bottle containing potassium carbonate. Check the airtightness of the gas collector, and then connect it to the gas outlet pipe of the test device.

[0050] II. Experimental Procedure:

[0051] 1. Turn on the heater and control the temperature of the heater.

[0052] 2. First, heat the closed water tank to generate water vapor, which is then introduced into the test system to purge the air from the system. Then, open the hydrogen sulfide cylinder to control the flow rate, and finally, open the oxygen cylinder to control the flow rate.

[0053] 3. Collection of reaction gases: The gases generated in the reaction first pass through a potassium carbonate gas collection bottle to absorb the unreacted excess hydrogen sulfide gas and water vapor. The gases not collected by the potassium carbonate collection bottle are then collected in a gas collection bottle filled with water and flow meter into the gas tank.

[0054] 4. End of reaction: When the flow rate of the flow meter before the gas cylinder approaches the preset value of 0.05L / min, turn off the hydrogen sulfide cylinder and the oxygen cylinder in sequence, and disconnect the reaction system from the receiving system.

[0055] 5. Extraction of ferrous sulfate: Turn off the heating furnace, stop adding water, cool to room temperature, remove the quartz tube, dissolve the solid in water, filter out the insoluble matter, the solution is an aqueous solution of ferrous sulfate, evaporate the aqueous solution, and crystallize to obtain ferrous sulfate crystals.

[0056] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0057] This application provides a method for preparing hydrogen from sulfuric acid residue, the method comprising:

[0058] S11. The first mixed gas is chemically reacted with sulfuric acid residue to obtain ferrous sulfate and a second mixed gas; wherein, the first mixed gas includes hydrogen sulfide gas, water vapor and oxygen;

[0059] S21. The second mixed gas is cooled and then separated to obtain hydrogen. Please refer to Table 1 for specific process parameters.

[0060] Table 1. Process parameters for hydrogen production from sulfuric acid residue.

[0061]

[0062]

[0063] The results of the methods for preparing hydrogen from sulfuric acid residue in Examples 1-3 were evaluated, and the results are shown in Table 2.

[0064] Table 2. Indicators of ferrous sulfate crystals and hydrogen gas

[0065] Serial Number Purity % of solid ferrous sulfate crystals Ferrous sulfate yield (g) Hydrogen yield L Hydrogen purity % Example 1 90.1 2.01 0.52 93.1 Example 2 90.5 2.14 0.54 92.1 Example 3 90.8 2.24 0.56 93.4

[0066] The method for preparing hydrogen from sulfuric acid residue in this application achieves high purity of ferrous sulfate and hydrogen, and the yield of ferrous sulfate and hydrogen is considerable.

[0067] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing hydrogen from sulfuric acid residue, characterized in that, The method includes: The first mixed gas is chemically reacted with sulfuric acid residue to obtain ferrous sulfate and a second mixed gas; wherein the first mixed gas includes hydrogen sulfide gas, water vapor and oxygen; The second mixed gas is cooled and then separated to obtain hydrogen. The molar ratio of the hydrogen sulfide gas, the water vapor, and the oxygen is (10~50):(30~40):(5~10); The temperature of the chemical reaction is 443~500K.

2. The method according to claim 1, characterized in that, The particle size of the sulfuric acid residue is 20-200 mesh.

3. The method according to claim 1, characterized in that, The temperature of the chemical reaction is 473K.

4. The method according to claim 1, characterized in that, The step of cooling and separating the second mixed gas to obtain hydrogen includes: The second mixed gas was cooled and then separated using an alkali metal carbonate solution to obtain hydrogen.

5. The method according to claim 4, characterized in that, The second mixed gas is 10 to 100 parts by volume relative to 1 part by volume of the alkali metal carbonate solution.

6. The method according to claim 1, characterized in that, The flow rate of the hydrogen sulfide gas is ≥0.1L / min.

7. The method according to claim 1, characterized in that, The oxygen flow rate is ≤0.05L / min.

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