High-temperature dechlorination agent for removing hydrogen chloride gas and preparation method thereof

Abstract

The application discloses a high-temperature dechlorination agent for removing hydrogen chloride gas and a preparation method thereof, and belongs to the technical field of dechlorination. The preparation method of the high-temperature dechlorination agent for removing hydrogen chloride gas comprises four steps of preparing sepiolite loaded active calcium powder, preparing copper-aluminum coated calcium carbonate whiskers, forming and calcining. The high-temperature dechlorination agent for removing hydrogen chloride gas obtained by the application has a chlorine penetration capacity of 78.5~81.7%, a crushing strength of 142~160 N·cm ‑1 , and an abrasion rate of 0.8~1.2%.

Description

Technical Field

[0001] This invention relates to a high-temperature dechlorination agent for removing hydrogen chloride gas and its preparation method, belonging to the field of dechlorination technology. Background Technology

[0002] Chlorides in coal evaporate and transform under the reducing atmosphere of the gasifier, with most precipitating as hydrogen chloride. Hydrogen chloride is a highly reactive and corrosive harmful gas, and the amount produced is estimated to be 1 mg / m³. 3 ~500mg / m 3 Hydrogen chloride readily corrodes equipment and pipelines. The Electric Power Research Institute (EPRI) in the United States specifically studied the corrosion of IGCC power generation systems by chlorine in coal gas and found that chlorine in coal gas increases the corrosion rate of low-alloy steel. Hydrogen chloride gas in coal gas also reacts readily with desulfurizing agents in the desulfurization system to form volatile chlorides, reducing the desulfurization effect and clogging the pipeline system. Therefore, the trace amounts of hydrogen chloride contained in the high-temperature coal gas produced by coal-fired power generation must be removed.

[0003] The removal of hydrogen chloride from high-temperature coal gas generally employs chemical absorption separation technology. Two common dechlorination processes exist: one involves injecting powdered dechlorinating agents into the gasifier to induce a chlorination reaction for in-furnace dechlorination; the other places the dechlorination reactor at the gasifier outlet, using an adsorbent for gas-phase dechlorination. Powdered dechlorinating agents generally suffer from low dechlorination efficiency and complex operation. The adsorbent-based gas-phase dechlorination method, which relies on the adsorption of hydrogen chloride from the coal gas by the dechlorinating agent, is highly efficient and simple to operate, thus its application is widespread. Most dechlorinating agents for adsorbing and removing hydrogen chloride, both domestically and internationally, employ the method of impregnating porous carriers with active components. However, the dechlorinating agents obtained by this method generally have low chlorine capacity and operate at relatively low temperatures, mostly belonging to room temperature or medium temperature dechlorinating agents. However, the outlet temperature of the coal gas produced by high-temperature gasifiers is as high as 500~650℃. If room temperature or medium temperature dechlorinating agents are used, a gas cooling system must be added, thereby increasing the entire production process and costs. Therefore, developing a high-temperature dechlorinating agent that can withstand high temperatures for a long time and has high chlorine capacity has very practical application value for reducing the dechlorination cost of high-temperature coal gas.

[0004] Chinese patent CN108654567A discloses a medium-high temperature dechlorination agent for removing HCl gas from flue gas and its preparation method. The dechlorination agent consists of an active ingredient, a carrier and additives, and a binder. The active ingredient has a mass percentage of 70-88%, the carrier and additives have a mass percentage of 10-25%, and the binder has a mass percentage of 2-5%. The active ingredient is obtained by high-temperature calcination of an active precursor component, which is obtained by mixing pretreated electrolytic stone with one or more of Ca(NO3)2, Zn(NO3)2, and NaHCO3. The medium-high temperature dechlorination agent obtained by this patent can withstand high dechlorination operating temperatures, but its chlorine penetration capacity is low, not exceeding 80%.

[0005] Chinese patent CN114797758A discloses a high-temperature dechlorination agent and its preparation method, comprising the following components in parts by weight: 25-50 parts of hydrated alumina, 3-40 parts of magnesium hydroxide, 15-65 parts of magnesium oxide, and 0-12 parts of binder. This invention uses self-made hydrated alumina with a high specific surface area, and uses hydrated alumina, magnesium oxide, and magnesium hydroxide as the main active components to prepare the high-temperature dechlorination agent. This dechlorination agent can effectively remove chlorine-containing gases from fuel gas or flue gas at high temperatures. The high-temperature dechlorination agent obtained by this patent is suitable for higher dechlorination temperatures, but it also has the drawback of relatively low chlorine penetration capacity, with the highest penetration capacity only reaching 81.1%.

[0006] As can be seen, high-temperature dechlorinating agents for removing hydrogen chloride gas still have problems such as low chlorine penetration capacity and insufficient mechanical properties under high-temperature operating conditions. Therefore, developing a high-temperature dechlorinating agent with high chlorine penetration capacity and good mechanical properties has very practical application value for removing hydrogen chloride from high-temperature coal gas. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a high-temperature dechlorination agent for removing hydrogen chloride gas and its preparation method, achieving the following objectives: to prepare a high-temperature resistant dechlorination agent for use under high-temperature operating conditions, which has the advantages of high chlorine penetration capacity and high crushing strength and low abrasion rate in terms of mechanical properties.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A high-temperature dechlorination agent for removing hydrogen chloride gas and its preparation method are disclosed. The high-temperature dechlorination agent for removing hydrogen chloride gas has a chlorine penetration capacity of 78.5-81.7% and a crushing strength of 142-160 N·cm. -1 The wear rate is 0.8~1.2%;

[0010] The preparation method of the high-temperature dechlorination agent for removing hydrogen chloride gas includes four steps: preparing sepiolite-supported active calcium powder, preparing copper-aluminum coated calcium carbonate whiskers, molding, and calcination.

[0011] The following are further improvements to the above technical solution:

[0012] Step 1: Preparation of sepiolite-supported active calcium powder

[0013] Calcium chloride and anhydrous ethanol were added to the reaction vessel and stirred until completely dissolved. Then sepiolite was added and stirred at high speed until the sepiolite was evenly dispersed. The stirring speed was then reduced to low speed, and sodium hydroxide aqueous solution was added to the vessel. After stirring at low speed until the reaction was complete, the mixture was washed and dried to obtain sepiolite-supported active calcium powder.

[0014] The sepiolite has a particle size of 0.01~1μm;

[0015] The sodium hydroxide aqueous solution contains 8-18 wt% sodium hydroxide.

[0016] The mass ratio of calcium chloride, anhydrous ethanol, sepiolite, and sodium hydroxide aqueous solution is 14~40:150~420:20~45:25~70;

[0017] The high-speed stirring has a stirring rate of 2500~4000 rpm;

[0018] The sepiolite is to be dispersed evenly, and the stirring and dispersing time is 2-6 hours.

[0019] The low-speed stirring has a stirring rate of 800~1600 rpm;

[0020] The low-speed stirring reaction is complete, and the reaction time is 6-11 hours;

[0021] The washing process involves washing with anhydrous ethanol 3 to 5 times, with the amount of anhydrous ethanol used each time being equal to the mass of the solid being washed.

[0022] The drying process involves a drying temperature of 70-95℃ and a drying time of 8-15 hours.

[0023] Step 2: Preparation of copper-aluminum coated calcium carbonate whiskers

[0024] Calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water were added to a high-speed dispersion vessel and stirred at high speed to form a stable and uniform suspension. While maintaining high-speed stirring, the temperature was raised and kept constant until the reaction temperature was reached. Then, urea was added to control the pH value of the reaction system at 5.9~6.8. After the reaction was completed, the temperature was lowered to room temperature, and then filtered, washed, and dried to obtain copper-aluminum coated calcium carbonate whiskers.

[0025] The calcium carbonate whiskers have a diameter of 0.5~1.2μm and a length of 8~30μm;

[0026] The mass ratio of calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water is 40~90:35~65:14~30:230~460;

[0027] The high-speed stirring has a stirring rate of 4000~5500 rpm;

[0028] The reaction temperature is 60~80℃;

[0029] After the reaction is completed, the reaction time is 6 to 10 hours;

[0030] The washing process involves washing the filtered solid with deionized water until the pH of the washing solution is neutral.

[0031] The drying process involves a drying temperature of 85-110℃ and a drying time of 13-18 hours.

[0032] Step 3, Shaping

[0033] Sepiolite-loaded active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite are placed in a high-speed mixer and mixed evenly at high speed to obtain a mixed powder. Then, the mixed powder and deionized water are added to a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the shaped high-temperature dechlorination agent granules are obtained.

[0034] The composite pore-forming agent is a mixture of starch and oxalate powder;

[0035] The oxalate powder is one or a mixture of any two or more of calcium oxalate, iron oxalate, magnesium oxalate, copper oxalate, manganese oxalate, and zinc oxalate in any mass ratio.

[0036] The oxalate powder has a particle size of 0.1~1μm;

[0037] The mass ratio of starch to oxalate powder is 39~78:10;

[0038] The composite accelerator is a mixture of carbonate powder and aluminate powder;

[0039] The carbonate powder is one or a mixture of any two or more of magnesium carbonate, zinc carbonate, and manganese carbonate in any mass ratio.

[0040] The aluminate powder is one or a mixture of any two or more of zinc aluminate, magnesium aluminate, and calcium aluminate in any mass ratio.

[0041] The particle size of the carbonate powder is 0.1~1μm;

[0042] The aluminate powder has a particle size of 0.1~1μm;

[0043] The mass ratio of the carbonate powder to the aluminate powder is 40~90:13;

[0044] The active adsorbent is one or a mixture of any two or more of magnesium stannate, copper stannate, and calcium stannate in any mass ratio.

[0045] The particle size of the pseudoboehmite is 0.1~2μm;

[0046] The mass ratio of the sepiolite-supported active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite is 40~100:8~25:5~18:1~7:0.5~4:10~35.

[0047] The mass ratio of the mixed powder to deionized water is 55~100:14;

[0048] The high-speed stirring process ensures uniform mixing, with a stirring speed of 150-300 rpm and a stirring time of 1-2.5 hours.

[0049] The drying process involves a drying temperature of 70-85℃ and a drying time of 15-24 hours.

[0050] The elongated particles have a cross-sectional diameter of 2-6 mm and a length of 9-17 mm.

[0051] Step 4, roasting

[0052] The original high-temperature dechlorinating agent particles were calcined at 550~750℃ for 3~6 hours and then cooled to room temperature to obtain a high-temperature dechlorinating agent that removes hydrogen chloride gas.

[0053] Compared with the prior art, the present invention achieves the following beneficial effects:

[0054] 1. The sepiolite-loaded active calcium powder prepared by this invention plays a crucial role in improving the adsorption and removal performance of high-temperature dechlorination agents. Utilizing the huge specific surface area and strong adsorption properties of sepiolite, a large number of calcium ions are first adsorbed on the inner and outer pore walls of sepiolite. Under the action of sodium hydroxide, the calcium ions precipitate as calcium hydroxide on the inner and outer pore walls of sepiolite and are adsorbed on the inner and outer pore walls of sepiolite. After high-temperature calcination, the calcium hydroxide decomposes into calcium oxide. Thus, the sepiolite contained in the high-temperature dechlorination agent has a large amount of calcium oxide attached to the inner and outer surfaces of its pore walls. Since calcium oxide has a particularly strong ability to adsorb and remove hydrogen chloride, sepiolite loaded with active calcium has a very significant effect on improving the chlorine penetration capacity of the high-temperature dechlorination agent.

[0055] 2. To improve the crushing strength and wear resistance of the high-temperature dechlorinating agent, this invention uses calcium carbonate whiskers to comprehensively strengthen and toughen the dechlorinating agent. To further enhance the strengthening and toughening effect of the calcium carbonate whiskers by forming a dense sinter with the other raw materials of the dechlorinating agent, this invention uses aluminum sulfate and copper sulfate as raw materials and employs a precipitation method to coat the calcium carbonate whiskers with copper and aluminum. Copper and aluminum ions first adhere tightly to the surface of the calcium carbonate whiskers in the form of hydroxide precipitates or alkaline complexes. Then, during the calcination of the dechlorinating agent, the copper and aluminum hydroxide precipitates or alkaline complexes decompose to generate oxides. During this decomposition process, i.e., the formation of copper and aluminum oxides, the copper and aluminum oxides can sinter together with other powder raw materials to form a relatively dense sintered product. Therefore, the toughening and strengthening effect of the calcium carbonate whiskers is greatly improved. Moreover, the newly formed copper and aluminum oxides have high reactivity with hydrogen chloride, which can also greatly improve the dechlorinating agent's ability to remove hydrogen chloride.

[0056] 3. The composite pore-forming agent added in this invention is composed of starch and oxalate powder. Starch has a low decomposition temperature and a relatively fast decomposition rate, while oxalate powder has a high decomposition temperature and a slow decomposition rate. The combination of these two can form micropores with a gradient distribution of pore size inside the dechlorinating agent. The gradient distribution of multi-level pore size can not only appropriately reduce the permeation resistance of high-temperature coal gas inside the dechlorinating agent and improve the adsorption and removal efficiency, but also control the adsorption residence time of hydrogen chloride contained in high-temperature coal gas inside the dechlorinating agent, so that hydrogen chloride can fully react with the active substances inside the dechlorinating agent, thereby maximizing the penetration chlorine capacity of the high-temperature dechlorinating agent.

[0057] 4. The composite accelerator added in this invention consists of carbonate powder and aluminate powder. The carbonate powder includes magnesium carbonate, zinc carbonate, and manganese carbonate. These three carbonates decompose into corresponding metal oxides during high-temperature calcination. During this decomposition process, the carbonate powder plays a certain role in creating pores. The generated magnesium, zinc, and manganese metal oxides are all strongly alkaline metal oxides with very high reactivity with hydrogen chloride, thus significantly promoting the adsorption and removal of hydrogen chloride. The aluminate powder includes zinc aluminate, magnesium aluminate, and calcium aluminate. These three aluminates have good high-temperature resistance and a certain degree of alkalinity. Their main function is to enhance the adsorption capacity of the high-temperature dechlorinating agent for hydrogen chloride under high-temperature conditions, making the residence time of hydrogen chloride gas in the micropores inside the dechlorinating agent longer. This further prolongs the contact time and reaction time between the active substance and hydrogen chloride, thereby improving the penetration chlorine capacity of the high-temperature dechlorinating agent.

[0058] 5. The high-temperature dechlorination agent for removing hydrogen chloride gas obtained by this invention has a chlorine penetration capacity of 78.5%~81.7% and a crushing strength of 142~160 N·cm. -1 The wear rate is 0.8~1.2%. Attached Figure Description

[0059] Figure 1 The high-temperature dechlorination agent for removing hydrogen chloride gas obtained in Example 1 is shown in a scanning electron microscope image with a cross-section magnified 5000 times.

[0060] Figure 2 The image shows a scanning electron microscope (SEM) image of the cross-section of the high-temperature dechlorinating agent obtained in Comparative Example 4, which removes hydrogen chloride gas. The image is magnified 5000 times. Detailed Implementation

[0061] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0062] Example 1: A method for preparing a high-temperature dechlorination agent for removing hydrogen chloride gas.

[0063] Step 1: Preparation of sepiolite-supported active calcium powder

[0064] Calcium chloride and anhydrous ethanol were added to the reaction vessel and stirred until completely dissolved. Then sepiolite was added and stirred at high speed until the sepiolite was evenly dispersed. The stirring speed was then reduced to low speed, and sodium hydroxide aqueous solution was added to the vessel. After stirring at low speed until the reaction was complete, the mixture was washed and dried to obtain sepiolite-supported active calcium powder.

[0065] The sepiolite has a particle size of 0.5 μm;

[0066] The sodium hydroxide aqueous solution contains 11 wt% sodium hydroxide.

[0067] The mass ratio of calcium chloride, anhydrous ethanol, sepiolite, and sodium hydroxide aqueous solution is 19:300:28:50.

[0068] The high-speed stirring has a stirring rate of 3500 rpm;

[0069] The sepiolite is to be dispersed evenly, and the stirring and dispersing time is 5 hours.

[0070] The low-speed stirring has a stirring rate of 1300 rpm;

[0071] The low-speed stirring reaction was completed, and the reaction time was 8 hours;

[0072] The washing process involves washing four times with anhydrous ethanol, with the amount of anhydrous ethanol used each time being equal to the mass of the solid being washed.

[0073] The drying process involves a drying temperature of 80°C and a drying time of 11 hours.

[0074] Step 2: Preparation of copper-aluminum coated calcium carbonate whiskers

[0075] Calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water were added to a high-speed dispersion vessel and stirred at high speed to form a stable and uniform suspension. While maintaining high-speed stirring, the temperature was raised and kept constant until the reaction temperature was reached. Then, urea was added to control the pH value of the reaction system at 6.3. After the reaction was completed, the temperature was lowered to room temperature, and then filtered, washed, and dried to obtain copper-aluminum coated calcium carbonate whiskers.

[0076] The calcium carbonate whiskers have a diameter of 1 μm and a length of 15 μm;

[0077] The mass ratio of calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water is 60:45:19:330.

[0078] The high-speed stirring has a stirring rate of 4800 rpm;

[0079] The reaction temperature is 75°C;

[0080] The reaction was completed after 9 hours.

[0081] The washing process involves washing the filtered solid with deionized water until the pH of the washing solution is neutral.

[0082] The drying process is carried out at a temperature of 100°C for 15 hours.

[0083] Step 3, Shaping

[0084] Sepiolite-loaded active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite are placed in a high-speed mixer and mixed evenly at high speed to obtain a mixed powder. Then, the mixed powder and deionized water are added to a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the shaped high-temperature dechlorination agent granules are obtained.

[0085] The composite pore-forming agent is a mixture of starch and oxalate powder;

[0086] The oxalate powder is calcium oxalate;

[0087] The oxalate powder has a particle size of 0.4 μm;

[0088] The mass ratio of starch to oxalate powder is 65:10;

[0089] The composite accelerator is a mixture of carbonate powder and aluminate powder;

[0090] The carbonate powder is magnesium carbonate;

[0091] The aluminate powder is zinc aluminate;

[0092] The carbonate powder has a particle size of 0.4 μm;

[0093] The aluminate powder has a particle size of 0.6 μm;

[0094] The mass ratio of the carbonate powder to the aluminate powder is 50:13;

[0095] The active adsorbent is magnesium stannate;

[0096] The particle size of the pseudoboehmite is 0.6 μm;

[0097] The mass ratio of the sepiolite-supported active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite is 70:18:11:4:2:19.

[0098] The mass ratio of the mixed powder to deionized water is 87:14;

[0099] The high-speed stirring process ensures uniform mixing at a stirring speed of 250 rpm for 2 hours.

[0100] The drying process is carried out at a temperature of 80°C for 19 hours.

[0101] The elongated granules have a cross-sectional diameter of 5 mm and a length of 16 mm.

[0102] Step 4, roasting

[0103] The original high-temperature dechlorination agent particles were calcined at 650°C for 5 hours and then cooled to room temperature to obtain a high-temperature dechlorination agent that removes hydrogen chloride gas.

[0104] Example 2: A method for preparing a high-temperature dechlorination agent for removing hydrogen chloride gas.

[0105] Step 1: Preparation of sepiolite-supported active calcium powder

[0106] Calcium chloride and anhydrous ethanol were added to the reaction vessel and stirred until completely dissolved. Then sepiolite was added and stirred at high speed until the sepiolite was evenly dispersed. The stirring speed was then reduced to low speed, and sodium hydroxide aqueous solution was added to the vessel. After stirring at low speed until the reaction was complete, the mixture was washed and dried to obtain sepiolite-supported active calcium powder.

[0107] The sepiolite has a particle size of 0.01 μm;

[0108] The sodium hydroxide aqueous solution contains 8 wt% sodium hydroxide.

[0109] The mass ratio of calcium chloride, anhydrous ethanol, sepiolite, and sodium hydroxide aqueous solution is 14:150:20:25.

[0110] The high-speed stirring has a stirring rate of 2500 rpm;

[0111] The sepiolite is to be evenly dispersed, and the stirring and dispersion time is 2 hours.

[0112] The low-speed stirring has a stirring rate of 800 rpm;

[0113] The low-speed stirring reaction was completed within 6 hours;

[0114] The washing process involves washing three times with anhydrous ethanol, with the amount of anhydrous ethanol used each time being equal to the mass of the solid being washed.

[0115] The drying process is carried out at a temperature of 70°C for 8 hours.

[0116] Step 2: Preparation of copper-aluminum coated calcium carbonate whiskers

[0117] Calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water were added to a high-speed dispersion vessel and stirred at high speed to form a stable and uniform suspension. While maintaining high-speed stirring, the temperature was raised and kept constant until the reaction temperature was reached. Then, urea was added to control the pH value of the reaction system at 5.9. After the reaction was completed, the temperature was lowered to room temperature, and then filtered, washed, and dried to obtain copper-aluminum coated calcium carbonate whiskers.

[0118] The calcium carbonate whiskers have a diameter of 0.5 μm and a length of 8 μm.

[0119] The mass ratio of calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water is 40:35:14:230.

[0120] The high-speed stirring has a stirring rate of 4000 rpm;

[0121] The reaction temperature is 60°C;

[0122] The reaction takes 6 hours to complete.

[0123] The washing process involves washing the filtered solid with deionized water until the pH of the washing solution is neutral.

[0124] The drying process was carried out at a temperature of 85°C for 13 hours.

[0125] Step 3, Shaping

[0126] Sepiolite-loaded active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite are placed in a high-speed mixer and mixed evenly at high speed to obtain a mixed powder. Then, the mixed powder and deionized water are added to a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the shaped high-temperature dechlorination agent granules are obtained.

[0127] The composite pore-forming agent is a mixture of starch and oxalate powder;

[0128] The oxalate powder is ferric oxalate;

[0129] The oxalate powder has a particle size of 0.1 μm;

[0130] The mass ratio of starch to oxalate powder is 39:10;

[0131] The composite accelerator is a mixture of carbonate powder and aluminate powder;

[0132] The carbonate powder is zinc carbonate;

[0133] The aluminate powder is magnesium aluminate;

[0134] The carbonate powder has a particle size of 0.1 μm;

[0135] The aluminate powder has a particle size of 0.1 μm;

[0136] The mass ratio of the carbonate powder to the aluminate powder is 40:13;

[0137] The active adsorbent is copper stannate;

[0138] The particle size of the pseudoboehmite is 0.1 μm;

[0139] The mass ratio of the sepiolite-supported active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite is 40:8:5:1:0.5:10.

[0140] The mass ratio of the mixed powder to deionized water is 55:14.

[0141] The high-speed stirring is used to mix the ingredients evenly. The stirring speed is 150 rpm and the stirring time is 1 hour.

[0142] The drying process is carried out at a temperature of 70°C for 15 hours.

[0143] The elongated granules have a cross-sectional diameter of 2 mm and a length of 9 mm.

[0144] Step 4, roasting

[0145] The original high-temperature dechlorination agent particles were calcined at 550°C for 3 hours and then cooled to room temperature to obtain a high-temperature dechlorination agent that removes hydrogen chloride gas.

[0146] Example 3: A method for preparing a high-temperature dechlorination agent for removing hydrogen chloride gas.

[0147] Step 1: Preparation of sepiolite-supported active calcium powder

[0148] Calcium chloride and anhydrous ethanol were added to the reaction vessel and stirred until completely dissolved. Then sepiolite was added and stirred at high speed until the sepiolite was evenly dispersed. The stirring speed was then reduced to low speed, and sodium hydroxide aqueous solution was added to the vessel. After stirring at low speed until the reaction was complete, the mixture was washed and dried to obtain sepiolite-supported active calcium powder.

[0149] The sepiolite has a particle size of 1 μm;

[0150] The sodium hydroxide aqueous solution contains 18 wt% sodium hydroxide.

[0151] The mass ratio of calcium chloride, anhydrous ethanol, sepiolite, and sodium hydroxide aqueous solution is 40:420:45:70.

[0152] The high-speed stirring has a stirring rate of 4000 rpm;

[0153] The sepiolite is to be dispersed evenly, and the stirring and dispersing time is 6 hours.

[0154] The low-speed stirring has a stirring rate of 1600 rpm;

[0155] The low-speed stirring reaction was completed in 11 hours;

[0156] The washing process involves washing five times with anhydrous ethanol, with the amount of anhydrous ethanol used each time being equal to the mass of the solid being washed.

[0157] The drying process involves a drying temperature of 95°C and a drying time of 15 hours.

[0158] Step 2: Preparation of copper-aluminum coated calcium carbonate whiskers

[0159] Calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water were added to a high-speed dispersion vessel and stirred at high speed to form a stable and uniform suspension. While maintaining high-speed stirring, the temperature was raised and kept constant until the reaction temperature was reached. Then, urea was added to control the pH of the reaction system at 6.8. After the reaction was completed, the temperature was lowered to room temperature, and then filtered, washed, and dried to obtain copper-aluminum coated calcium carbonate whiskers.

[0160] The calcium carbonate whiskers have a diameter of 1.2 μm and a length of 30 μm;

[0161] The mass ratio of calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water is 90:65:30:460.

[0162] The high-speed stirring has a stirring rate of 5500 rpm;

[0163] The reaction temperature is 80°C;

[0164] The reaction was completed after 10 hours.

[0165] The washing process involves washing the filtered solid with deionized water until the pH of the washing solution is neutral.

[0166] The drying process involves a drying temperature of 110°C and a drying time of 18 hours.

[0167] Step 3, Shaping

[0168] Sepiolite-loaded active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite are placed in a high-speed mixer and mixed evenly at high speed to obtain a mixed powder. Then, the mixed powder and deionized water are added to a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the shaped high-temperature dechlorination agent granules are obtained.

[0169] The composite pore-forming agent is a mixture of starch and oxalate powder;

[0170] The oxalate powder is magnesium oxalate;

[0171] The oxalate powder has a particle size of 1 μm;

[0172] The mass ratio of starch to oxalate powder is 78:10;

[0173] The composite accelerator is a mixture of carbonate powder and aluminate powder;

[0174] The carbonate powder is manganese carbonate;

[0175] The aluminate powder is calcium aluminate;

[0176] The particle size of the carbonate powder is 1 μm;

[0177] The aluminate powder has a particle size of 1 μm;

[0178] The mass ratio of the carbonate powder to the aluminate powder is 90:13;

[0179] The active adsorbent is calcium stannate;

[0180] The particle size of the pseudoboehmite is 2 μm;

[0181] The mass ratio of the sepiolite-supported active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite promoter, active adsorbent, and pseudoboehmite is 100:25:18:7:4:35.

[0182] The mass ratio of the mixed powder to deionized water is 100:14;

[0183] The high-speed stirring process ensures uniform mixing at a stirring speed of 300 rpm for 2.5 hours.

[0184] The drying process involves a drying temperature of 85°C and a drying time of 24 hours.

[0185] The elongated granules have a cross-sectional diameter of 6 mm and a length of 17 mm.

[0186] Step 4, roasting

[0187] The original high-temperature dechlorinating agent particles were calcined at 750°C for 6 hours and then cooled to room temperature to obtain a high-temperature dechlorinating agent that removes hydrogen chloride gas.

[0188] Example 4: A method for preparing a high-temperature dechlorination agent for removing hydrogen chloride gas.

[0189] Steps 1 and 2 are the same as in Example 1;

[0190] Step 3, Shaping

[0191] The oxalate powder is copper oxalate, and other operations are the same as in Example 1;

[0192] Step 4 is the same as in Example 1.

[0193] Example 5: A method for preparing a high-temperature dechlorination agent for removing hydrogen chloride gas.

[0194] Steps 1 and 2 are the same as in Example 1;

[0195] Step 3, Shaping

[0196] The oxalate powder is manganese oxalate, and other operations are the same as in Example 1;

[0197] Step 4 is the same as in Example 1.

[0198] Example 6: A method for preparing a high-temperature dechlorination agent for removing hydrogen chloride gas.

[0199] Steps 1 and 2 are the same as in Example 1;

[0200] Step 3, Shaping

[0201] The oxalate powder is zinc oxalate, and other operations are the same as in Example 1;

[0202] Step 4 is the same as in Example 1.

[0203] Comparative Example 1: Based on Example 1, step 1, preparing sepiolite-supported active calcium powder, was omitted. In step 3, during molding, 70 parts of sepiolite-supported active calcium powder were replaced with an equal amount of 70 parts of sepiolite. The specific operation is as follows:

[0204] Step 1, preparing sepiolite-supported active calcium powder, is omitted;

[0205] Step 2 is the same as in Example 1;

[0206] Step 3, Shaping

[0207] Replace 70 parts of sepiolite-loaded active calcium powder with 70 parts of sepiolite, and perform the same operations as in Example 1.

[0208] The sepiolite has a particle size of 0.5 μm;

[0209] Based on Example 1, 12 parts of stannate and 18 parts of molybdate were replaced with 30 parts of composite hydrothermal solvent, and other operations were the same as in Example 1;

[0210] Step 4 is the same as in Example 1.

[0211] Comparative Example 2: Based on Example 1, step 2 (preparing copper-aluminum coated calcium carbonate whiskers) was omitted. In step 3 (forming), 18 parts of copper-aluminum coated calcium carbonate whiskers were replaced with 18 parts of calcium carbonate whiskers. The specific operation is as follows:

[0212] Step 1 is the same as in Example 1;

[0213] Step 2 is omitted in the preparation of copper-aluminum coated calcium carbonate whiskers;

[0214] Step 3, Shaping

[0215] Replace 18 parts of copper-aluminum coated calcium carbonate whiskers with 18 parts of calcium carbonate whiskers, and perform the other operations as in Example 1.

[0216] The calcium carbonate whiskers have a diameter of 1 μm and a length of 15 μm;

[0217] Based on Example 1, 12 parts of stannate were replaced with 12 parts of composite hydrothermal solvent, and other operations were the same as in Example 1;

[0218] Step 4 is the same as in Example 1.

[0219] Comparative Example 3: Based on Example 1, in step 3, during molding, starch was not added to the composite pore-forming agent; only oxalate powder was added. Eleven parts of the composite pore-forming agent were replaced with eleven parts of oxalate powder. The specific operation is as follows:

[0220] Steps 1 and 2 are the same as in Example 1;

[0221] Step 3, Shaping

[0222] Replace 11 parts of the composite pore-forming agent with 11 parts of oxalate powder in equal amounts, and perform the other operations as in Example 1;

[0223] The oxalate powder has a particle size of 0.4 μm;

[0224] Step 4 is the same as in Example 1.

[0225] Comparative Example 4: Based on Example 1, in step 3, during molding, oxalate powder was not added to the composite pore-forming agent; only starch was added. Eleven parts of the composite pore-forming agent were replaced with eleven parts of starch in equal amounts. The specific operation is as follows:

[0226] Steps 1 and 2 are the same as in Example 1;

[0227] Step 3, Shaping

[0228] Replace 11 parts of the composite pore-forming agent with 11 parts of starch in equal amounts, and perform the other operations as in Example 1;

[0229] Step 4 is the same as in Example 1.

[0230] Comparative Example 5: Based on Example 1, in step 3, during molding, no composite accelerator was added. Instead, 4 parts of the composite accelerator were replaced with 4 parts of pseudoboehmite. The specific operation is as follows:

[0231] Steps 1 and 2 are the same as in Example 1;

[0232] Step 3, Shaping

[0233] Based on Example 1, replace 4 parts of composite accelerator with 4 parts of pseudoboehmite in equal amounts, and perform the other operations as in Example 1;

[0234] Step 4 is the same as in Example 1.

[0235] Comparative Example 6: Based on Example 1, in step 3, during molding, no active adsorbent was added. Instead, 2 parts of active adsorbent were replaced with 2 parts of pseudoboehmite. The specific operation is as follows:

[0236] Steps 1 and 2 are the same as in Example 1;

[0237] Step 3, Shaping

[0238] Based on Example 1, replace 2 parts of active adsorbent with 2 parts of pseudoboehmite in equal amounts, and perform the other operations as in Example 1;

[0239] Step 4 is the same as in Example 1.

[0240] Performance testing:

[0241] The high-temperature dechlorination agents for removing hydrogen chloride gas obtained in Examples 1, 2, 3, 4, 5, 6 and Comparative Examples 1, 2, 3, 4, 5, 6 were tested for the following indicators:

[0242] 1. Chlorine penetration capacity test method: A fixed-bed evaluation was used. The diameter of the quartz glass reactor was 10 mm. 6 mL of high-temperature dechlorination agent was uniformly packed in the middle of the reactor, and 3 mL of 10-20 mesh quartz sand was packed above and below the high-temperature dechlorination agent. The inlet gas was simulated high-temperature coal gas with hydrogen chloride (simulated high-temperature coal gas was introduced with hydrogen chloride after passing through a chlorine mixing bottle), and the hydrogen chloride content in the inlet gas was 2000-3500 mg / m³. 3 The gas space velocity is 6000 h⁻¹. -1 At atmospheric pressure and an evaluation temperature of 650℃, the hydrogen chloride content in the outlet gas exceeds 1 mg / m³. 3 The time is called penetration. According to the formula: Penetration chlorine capacity = (mass content of chlorine in the dechlorinating agent after penetration) / (total mass of dechlorinating agent after penetration) × 100%, the penetration chlorine capacity of the high-temperature dechlorinating agent can be obtained.

[0243] 2. Crushing strength: The crushing strength shall be tested in accordance with the "HG / T 2782-2011 Determination of Crushing Resistance of Fertilizer Catalyst Particles";

[0244] 3. Wear rate: The wear rate is tested in accordance with "HG / T 2976-2011 Determination of Wear Rate of Fertilizer Catalysts";

[0245] The specific test results are shown in Table 1:

[0246] Table 1

[0247]

[0248] As can be seen from the data in Table 1, the breakthrough chlorine capacity of Examples 1-6 is all above 78%, and the crushing strength is all above 140 N·cm. -1The wear rate did not exceed 1.2%, indicating that the high-temperature dechlorinating agent obtained by this invention has a very high chlorine penetration capacity under high-temperature and high-space-velocity operating conditions. It also exhibits excellent performance in terms of crushing strength and wear rate. This demonstrates that the high-temperature dechlorinating agent for removing hydrogen chloride gas prepared by this invention not only has a high chlorine penetration capacity but also boasts advantages in terms of crushing strength and low wear rate. In Comparative Example 1, sepiolite was added directly without loaded active calcium, resulting in a drastic decrease in the chlorine penetration capacity to 41.7%, while the crushing strength and wear rate remained largely unchanged. This indicates that sepiolite loaded with active calcium has a very significant effect on the adsorption and removal of hydrogen chloride by the high-temperature dechlorinating agent. The synergistic effect may be due to the large specific surface area of ​​sepiolite, which can adsorb a large number of calcium ions. After these calcium ions react with sodium hydroxide, they precipitate as calcium hydroxide and are adsorbed on the inner and outer surfaces of sepiolite. After high-temperature calcination, the calcium hydroxide decomposes into calcium oxide. Thus, the sepiolite contained in the high-temperature dechlorination agent has a large amount of calcium oxide adsorbed on its inner and outer surfaces. Calcium oxide has a particularly strong ability to adsorb and remove hydrogen chloride. Therefore, after sepiolite is loaded with active calcium, it will significantly improve the penetration chlorine capacity of the high-temperature dechlorination agent. In Comparative Example 2, the added calcium carbonate whiskers, without copper-aluminum coating, also showed a significant decrease in the penetration chlorine capacity, dropping to 69.5%, and the crushing strength decreased to 132 N·cm. -1 The wear rate increased to 2.3%, indicating that the copper-aluminum coated calcium carbonate whiskers not only have a very high adsorption and removal effect on hydrogen chloride, but also improve the mechanical properties of the high-temperature dechlorinating agent. This may be because, during the high-temperature calcination step, the copper and aluminum in the copper-aluminum coated calcium carbonate whiskers are oxidized into copper oxide and aluminum oxide, respectively. These two oxides have very high reactivity with hydrogen chloride. Moreover, during the high-temperature calcination stage, the process of oxidizing copper and aluminum into copper oxide and aluminum oxide involves a certain sintering effect with the composite pore-forming agent, composite accelerator, active adsorbent, and boehmite of the high-temperature dechlorinating agent. This enhances the overall bonding strength of the calcium carbonate whiskers to the high-temperature dechlorinating agent, thus further enhancing the mechanical properties of the high-temperature dechlorinating agent. In Comparative Example 3, only oxalate powder was added to the composite pore-forming agent. The chlorine penetration capacity of Comparative Example 3 decreased to 54%, but the crushing strength increased to 175 N·cm. -1The wear rate decreased to 0.5%, indicating that the combination of starch and oxalate powder in the composite pore-forming agent effectively promotes the removal capacity of hydrogen chloride by the high-temperature dechlorinating agent. However, this combination has a certain negative impact on the mechanical properties of the high-temperature dechlorinating agent. This may be because when only oxalate powder is added as a pore-forming agent, the decomposition temperature of oxalate powder is high and the decomposition rate is slow, resulting in a small internal pore size of the final high-temperature dechlorinating agent. At high space velocities, the resistance to the permeation and adsorption of hydrogen chloride gas into the high-temperature dechlorinating agent is large, leading to a decrease in the permeation capacity of chlorine. However, when only oxalate powder is added as a pore-forming agent, the internal pore size of the high-temperature dechlorinating agent is small, which can significantly improve the dechlorinating agent's performance. The mechanical properties of the composite pore-forming agent were significantly reduced. In Comparative Example 4, only starch was added to the composite pore-forming agent, resulting in a very significant decrease in the chlorine penetration capacity, a drastic decrease in crushing strength, and a substantial increase in the wear rate to 2.9%. This indicates that using starch alone as a pore-forming agent leads to excessively large pore sizes within the dechlorinating agent. In high-air-velocity operating environments, the resistance to high-temperature gas is relatively small, resulting in a shorter residence time of the high-temperature gas inside the dechlorinating agent. Consequently, the active substances inside the dechlorinating agent do not have enough time to undergo sufficient chemical adsorption with hydrogen chloride. Furthermore, using starch alone as a pore-forming agent significantly damages the mechanical properties of the high-temperature dechlorinating agent. This is likely due to the low decomposition temperature and high decomposition rate of starch, which contributes to the degradation of the dechlorinating agent at high temperatures. The formation of too many large-diameter micropores within the chlorinating agent severely degrades the mechanical properties of the high-temperature dechlorinating agent. In Comparative Example 5, without the addition of the composite accelerator, the breakthrough chlorine capacity significantly decreased to 72.3%, while the crushing strength and abrasion rate remained largely unchanged. This indicates that the composite accelerator has a very significant effect on improving the breakthrough chlorine capacity. The composite accelerator, composed of carbonates and aluminates, generates alkaline metal oxides through the decomposition of carbonates at high temperatures, which in turn produces more micropores with extremely fine pores. These alkaline metal oxides exhibit high reactivity with hydrogen chloride, and the small micropores increase the dechlorinating agent's adsorption capacity for hydrogen chloride. The combined effect of these two aspects increases the penetration chlorine capacity of the high-temperature dechlorinating agent. In Comparative Example 6, which did not contain an active adsorbent, the penetration chlorine capacity also decreased significantly. This is because the three active adsorbents, magnesium stannate, copper stannate, and calcium stannate, have high reactivity with hydrogen chloride at high temperatures and can form tin chloride. Correspondingly, the oxides formed by magnesium, copper, and calcium at high temperatures also have high reactivity with hydrogen chloride. Therefore, the active adsorbent has a very significant effect on improving the penetration chlorine capacity of the high-temperature dechlorinating agent. Moreover, the crushing strength and abrasion rate of Comparative Example 6 did not change much, indicating that the active adsorbent has no negative impact on the mechanical properties of the high-temperature dechlorinating agent.

[0249] Appendix Figure 1 Appendix Figure 2 These are scanning electron microscope (SEM) images, magnified 5000x, of the high-temperature dechlorination agents for removing hydrogen chloride gas obtained in Example 1 and Comparative Example 4, respectively. Figure 1As can be seen in the cross-section of the high-temperature dechlorination agent, there are many micropores of varying sizes. The rod-shaped structures distributed throughout the cross-section are calcium carbonate whiskers. The bond between the sintered matrix and the calcium carbonate whiskers is very tight, which is consistent with the high crushing strength and low abrasion rate of the high-temperature dechlorination agent measured in this invention. Figure 2 The micropores distributed in the middle have a pore size significantly larger than those in the surrounding area. Figure 1 And attached Figure 2 The calcium carbonate whiskers in the sample exhibited debonding from the sintered matrix, indicating that adding only starch as a pore-forming agent in Comparative Example 4 was insufficient to obtain a dense sintered structure, resulting in larger micropore sizes and ultimately a significant decrease in the mechanical properties of the high-temperature dechlorination agent.

[0250] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature dechlorination agent for removing hydrogen chloride gas, characterized in that: The preparation method of the high-temperature dechlorination agent for removing hydrogen chloride gas includes four steps: preparing sepiolite-supported active calcium powder, preparing copper-aluminum coated calcium carbonate whiskers, molding, and calcination. To prepare sepiolite-supported active calcium powder, calcium chloride and anhydrous ethanol are added to a reaction vessel and stirred until completely dissolved. Then, sepiolite is added and stirred at high speed until the sepiolite is evenly dispersed. The stirring speed is then reduced to low speed, and sodium hydroxide aqueous solution is added to the vessel. The reaction is continued at low speed until complete. After washing and drying, sepiolite-supported active calcium powder is obtained. To prepare copper-aluminum coated calcium carbonate whiskers, calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water are added to a high-speed dispersion vessel and stirred at high speed to form a stable and uniform suspension. While maintaining high-speed stirring, the temperature is raised and kept constant to the reaction temperature. Then, urea is added to control the pH value of the reaction system at 5.9~6.

8. After the reaction is completed, the temperature is lowered to room temperature, and then filtered, washed, and dried to obtain copper-aluminum coated calcium carbonate whiskers. The molding process involves placing sepiolite-loaded active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite into a high-speed mixer. After high-speed stirring and uniform mixing, a mixed powder is obtained. Then, the mixed powder and deionized water are added into a twin-screw extruder and extruded to obtain long strip-shaped particles. After drying, the molded high-temperature dechlorination agent granules are obtained. The composite pore-forming agent is a mixture of starch and oxalate powder; The composite accelerator is a mixture of carbonate powder and aluminate powder; The active adsorbent is one or a mixture of any two or more of magnesium stannate, copper stannate, and calcium stannate in any mass ratio.

2. The method for preparing the high-temperature dechlorination agent for removing hydrogen chloride gas according to claim 1, characterized in that: The sepiolite has a particle size of 0.01~1μm; The sodium hydroxide aqueous solution contains 8-18 wt% sodium hydroxide. The mass ratio of calcium chloride, anhydrous ethanol, sepiolite, and sodium hydroxide aqueous solution is 14~40:150~420:20~45:25~70.

3. The method for preparing the high-temperature dechlorination agent for removing hydrogen chloride gas according to claim 1, characterized in that: The calcium carbonate whiskers have a diameter of 0.5~1.2μm and a length of 8~30μm; The mass ratio of calcium carbonate whiskers, aluminum sulfate, copper sulfate, and deionized water is 40~90:35~65:14~30:230~460.

4. The method for preparing the high-temperature dechlorination agent for removing hydrogen chloride gas according to claim 1, characterized in that: The oxalate powder is one or a mixture of any two or more of calcium oxalate, iron oxalate, magnesium oxalate, copper oxalate, manganese oxalate, and zinc oxalate in any mass ratio. The oxalate powder has a particle size of 0.1~1μm; The mass ratio of starch to oxalate powder is 39~78:

10.

5. The method for preparing the high-temperature dechlorination agent for removing hydrogen chloride gas according to claim 1, characterized in that: The carbonate powder is one or a mixture of any two or more of magnesium carbonate, zinc carbonate, and manganese carbonate in any mass ratio. The aluminate powder is one or a mixture of any two or more of zinc aluminate, magnesium aluminate, and calcium aluminate in any mass ratio. The particle size of the carbonate powder is 0.1~1μm; The aluminate powder has a particle size of 0.1~1μm; The mass ratio of carbonate powder to aluminate powder is 40~90:

13.

6. The method for preparing the high-temperature dechlorination agent for removing hydrogen chloride gas according to claim 1, characterized in that: The mass ratio of the sepiolite-supported active calcium powder, copper-aluminum coated calcium carbonate whiskers, composite pore-forming agent, composite accelerator, active adsorbent, and pseudoboehmite is 40~100:8~25:5~18:1~7:0.5~4:10~35. The mass ratio of the mixed powder to deionized water is 55~100:

14.

7. The method for preparing the high-temperature dechlorination agent for removing hydrogen chloride gas according to claim 1, characterized in that: The calcination process involves calcining the original high-temperature dechlorinating agent particles at 550-750°C for 3-6 hours, followed by cooling to room temperature to obtain a high-temperature dechlorinating agent that removes hydrogen chloride gas.

8. The high-temperature dechlorinating agent for removing hydrogen chloride gas obtained by the preparation method according to any one of claims 1-7, characterized in that: The high-temperature dechlorination agent for removing hydrogen chloride gas has a chlorine penetration capacity of 78.5% to 81.7% and a crushing strength of 142 to 160 N·cm. -1 The wear rate is 0.8~1.2%.

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