A carbon-based catalyst raw material composition, a carbon-based catalyst, and a preparation method and application thereof

Abstract

The present application relates to coal gasification slag resource recycling and industrial flue gas desulfurization and denitrification technical field, disclose a kind of carbon-based catalyst raw material composition and carbon-based catalyst and its preparation method and application.The carbon-based catalyst raw material composition contains coal gasification slag, coking coal, coal pitch, binder and surfactant, the coal gasification slag contains 30~50 weight% SiO2, 5~15 weight% Al2O3, 1~12 weight% Fe2O3, 0.1~2 weight% TiO2 and 10~40 weight% amorphous carbon.The present application prepares carbon-based catalyst with the whole component of coal gasification slag and coking coal as main raw material, replaces coal quality active coke, and the catalytic performance of the prepared carbon-based catalyst is significantly improved, and the complete resource utilization of the whole component of coal gasification slag is realized, waste is turned into treasure, with good comprehensive benefit.

Description

Technical Field

[0001] This invention relates to the fields of coal gasification slag resource reuse and industrial flue gas desulfurization and denitrification technology, specifically to a carbon-based catalyst raw material composition, a carbon-based catalyst, its preparation method and application. Background Technology

[0002] Coal gasification technology, as a clean coal chemical technology, is mainly applied in industries such as coal-based chemical synthesis (methanol, olefins, etc.) and liquid fuel synthesis (dimethyl ether, gasoline, etc.). Coal gasification slag is a solid waste emitted during the coal gasification process, and its main current treatment methods are landfill and stockpiling. Landfilling causes heavy metal ions in the slag to seep into the soil and water bodies, resulting in underground environmental pollution; while stockpiling leads to waste of land resources and dust problems. With the large-scale promotion of coal gasification technology, the annual production of coal gasification slag in China has exceeded 33 million tons, making the harmless treatment of coal gasification slag an urgent issue.

[0003] The activated coke flue gas desulfurization and denitrification process was first proposed by Berbau Forschung in Germany, and later transferred to Mitsui Mining Co., Ltd. in Japan. After successful pilot-scale and industrial-scale trials in Japan, it was widely adopted for industrial production. This method targets the purification of industrial flue gas, simultaneously removing pollutants such as sulfur dioxide, nitrogen oxides, dust, dioxins, and heavy metals, while also enabling the resource utilization of sulfur dioxide and eliminating secondary pollution problems related to wastewater and waste residue. Based on these advantages, this process has been widely adopted in my country and is applied in industries such as steel, coking, non-ferrous metallurgy, and power generation. Activated coke, as the core component of this desulfurization and denitrification process, requires large quantities of coking coal, semi-coke, and anthracite for its preparation. According to the "GB29994-2013 Energy Consumption Limits for Unit Products of Coal-Based Activated Carbon," even at the advanced energy consumption level in activated coke production, the comprehensive energy consumption required to produce 1 ton of activated coke is equivalent to 2 tons of standard coal. How to reduce energy consumption in activated coke production has always been a hot issue of concern in the industry. In addition, as a catalyst, improving its performance is also a direction that the industry has been focusing on.

[0004] CN109433156A discloses a columnar activated coke and its preparation method. The method uses abraded activated coke powder as raw material, mixes it with a carbonaceous binder, and obtains columnar coke by extrusion molding. Then, activated coke for desulfurization and denitrification is prepared by adding steam in an inert atmosphere. However, the abraded activated coke powder contains high levels of sulfuric acid and ammonium sulfate, which releases large amounts of sulfur dioxide gas during high-temperature processes such as carbonization, causing corrosion and damage to production equipment and environmental pollution. Furthermore, abraded activated coke powder is generally used as a feedstock in sintering machines and boilers, and can be fully utilized on-site. Considering the costs of packaging and transportation, it is not practical as a raw material for activated coke production.

[0005] CN109987605A discloses a method for separating carbon-rich components from coal gasification slag using an aqueous medium and then preparing desulfurized and denitrified activated coke. The separated carbon-rich portion is combined with caking coal and long-flame coal, and after processes including crushing, sieving, kneading, molding, drying, carbonization, and activation, it is prepared as flue gas desulfurization and denitrification activated coke. However, according to the analysis and statistics of Ren Zhenyang et al. from Taiyuan University of Technology ("Experimental Study on Water-Media Gravity Separation of Gasification Slag and Preparation of Desulfurized and Denitrified Activated Coke from Separated Carbon [J] Journal of Coal Science and Technology, 2021, 46(04)"), the yield of the carbon-rich portion of the separated coal gasification slag using this method is only 8.37%, and the remaining components cannot be reused, thus failing to solve the problem of solid waste treatment of coal gasification slag.

[0006] CN112044400A discloses a method for preparing activated coke for flue gas desulfurization and denitrification by mixing lignite with a small amount of steel slag. Coal powder and steel slag powder are thoroughly mixed at a mass ratio of 6:1 to 9:1. Coal tar, glycerol, and water are added in a mass ratio of 2.1 to 2.4:1:1.2 to 1.4, and the mixture is stirred and kneaded. After carbonization and activation, columnar activated coke is produced. The steel slag has a high iron oxide content, generally 22.4% to 33.1%. In actual production, the iron oxide is usually first obtained through magnetic separation and recycled back into the furnace. The remaining portion can be sold as a commodity. Overall, it has achieved harmless utilization and has good economic value. However, using it for the preparation of activated coke is no longer practical.

[0007] CN105032389 and CN109589965A disclose methods for loading manganese-cerium bimetallic and vanadium active metal components onto activated coke by impregnating it with a manganese-cerium bimetallic solution and mixing it with a vanadium-containing complexing solution, in order to improve the desulfurization and denitrification efficiency of activated coke. However, such methods of adding exogenous metals are complex in preparation and generate waste liquid containing heavy metal ions, causing environmental pollution. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of low utilization rate of coal gasification slag and easy release of polluting gases by activated coke during catalyst preparation in existing technologies. This invention provides a carbon-based catalyst raw material composition, a carbon-based catalyst, its preparation method, and its application. This invention uses all components of coal gasification slag and coking coal as the main raw materials to prepare a carbon-based catalyst, replacing coal-based activated coke. The catalytic performance of the prepared carbon-based catalyst is significantly improved, while simultaneously achieving complete resource utilization of all components of the coal gasification slag, turning waste into treasure, and exhibiting good comprehensive benefits.

[0009] To achieve the above objectives, the present invention provides a carbon-based catalyst raw material composition comprising coal gasification slag, coking coal, coal tar pitch, binder and surfactant, wherein the coal gasification slag comprises 30-50% by weight of SiO2, 5-15% by weight of Al2O3, 1-12% by weight of Fe2O3, 0.1-2% by weight of TiO2 and 10-40% by weight of amorphous carbon.

[0010] Preferably, based on the total weight of coal gasification slag, coking coal, coal tar pitch, binder and surfactant, the content of coal gasification slag is 65-75% by weight, the content of coking coal is 20-30% by weight, the content of coal tar pitch is 1-3% by weight, the content of binder is 0.5-2% by weight, and the content of surfactant is 0.1-0.5% by weight.

[0011] Preferably, the adhesive is selected from one or more of gelatinized starch, carboxymethyl starch, and carboxymethyl cellulose.

[0012] Preferably, the surfactant is selected from sodium alkylbenzene sulfonate and / or potassium perfluoroalkyl sulfonate.

[0013] A second aspect of the present invention provides a method for preparing a carbon-based catalyst, wherein the carbon-based catalyst is prepared using the carbon-based catalyst raw material composition described above. The method includes the following steps: kneading, granulating, carbonizing, and activating coal gasification slag, coking coal, coal tar pitch, binder, and surfactant aqueous solution.

[0014] Preferably, the method includes the following steps:

[0015] (1) The coal gasification slag, coking coal and coal tar pitch are made into a mixed powder, and then mixed with the binder powder to obtain the raw material powder;

[0016] (2) The raw material powder is kneaded, granulated and dried with the surfactant aqueous solution to obtain a dried product;

[0017] (3) The dried product is carbonized under oxygen-deficient conditions to obtain a carbonized product;

[0018] (4) The carbonized product is activated under oxygen-deficient conditions and in the presence of superheated steam.

[0019] Preferably, in step (1), the proportion of the mixed powder passing through a 250-mesh sieve is >90%.

[0020] Preferably, the concentration of the surfactant aqueous solution is 0.5 to 1.5 by weight.

[0021] Preferably, in step (2), the amount of the surfactant aqueous solution added is 15 to 25% by weight of the amount of the raw material powder.

[0022] Preferably, the drying method is: cold air drying.

[0023] Preferably, the drying conditions include a temperature of 30~50℃ and a time of 10~15min.

[0024] Preferably, the carbonization conditions in step (3) include: the temperature at the feed end of the carbonization device is 380~420℃, the temperature at the discharge end is 750~850℃, and the residence time of the dried product at the discharge end of the carbonization device is 1~2h.

[0025] Preferably, the activation conditions in step (4) include: heating the carbonized product to 950~1050°C under oxygen-deficient conditions, then introducing superheated steam at 750~850°C into the activation device for 1~2 hours.

[0026] Preferably, in steps (3) and (4), the oxygen-deficient conditions include an oxygen content of 5-10% by volume.

[0027] A third aspect of the present invention provides a carbon-based catalyst prepared by the method described above.

[0028] Preferably, the carbon-based catalyst has an ignition point ≥440℃, an iodine adsorption value ≥500mg / g, and a specific surface area ≥400m². 2 / g, abrasion resistance ≥98%, compressive strength ≥40daN, desulfurization value ≥25mg / g, denitrification rate ≥40%.

[0029] The fourth aspect of the present invention provides the application of the carbon-based catalyst described above as a desulfurization and denitrification catalyst.

[0030] The method described in this invention prepares a carbon-based catalyst using coal gasification slag, coking coal, coal tar flakes, binder, and activator as raw materials. Firstly, the endogenous silicon and aluminum components in the coal gasification slag effectively prevent the agglomeration of softer, lower-ignition-point layered carbon components, forming a uniform and hard carbon-silicon-aluminum solid solution porous structure carrier. The endogenous titanium and iron active metals in the coal gasification slag act as denitrification active centers. The resulting catalyst has advantages such as large specific surface area, high ignition point, high mechanical strength, and high desulfurization and denitrification rates, making its industrial application more efficient, safe, and economical. Secondly, this invention does not require the addition of other exogenous active metals as active centers, thus improving the desulfurization and denitrification rates while preventing pollution caused by the catalyst production process and saving costs.

[0031] The method for preparing carbon-based catalysts described in this invention enables the full-component resource utilization of coal gasification slag, prevents environmental pollution, effectively reduces energy consumption in the production process of carbon-based catalysts, and is simple, low-cost, and easy to operate.

[0032] Compared with the prior art, the present invention has the following main advantages:

[0033] (1) Complete resource utilization of all components of coal gasification slag, realizing resource-based treatment of waste residue, preventing environmental pollution and saving land resources;

[0034] (2) Effectively reduces energy consumption in the production process of carbon-based catalysts, with its comprehensive energy consumption less than 30% of the advanced energy consumption value specified in standard GB 29994-2013.

[0035] (3) Give full play to the role of the C-Al2O3-SiO2-Fe2O3-TiO2 catalytic combination system in the catalyst to comprehensively improve the physicochemical performance of carbon-based catalysts.

[0036] (4) The endogenous titanium-iron active metal component of coal gasification slag is used as the reaction active center, without the need to add other exogenous active metals as active centers. This improves the denitrification efficiency while preventing pollution caused by the catalyst production process. Detailed Implementation

[0037] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0038] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0039] The inventors of this invention discovered that by using all components of coal gasification slag and coking coal as the main raw materials to replace coal-based activated coke, a decarbonization-based catalyst combining a C-Al2O3-SiO2 solid solution porous support with Fe2O3-TiO2 metal active centers can be prepared. When applied to the desulfurization and denitrification process of flue gas in the activated coke industry, it can effectively reduce energy consumption in the activated coke production process. Simultaneously, through the effect of the C-Al2O3-SiO2-Fe2O3-TiO2 combined system in the catalyst, various properties of the catalyst can be comprehensively improved, achieving complete resource utilization of all components of coal gasification slag, turning waste into treasure, and possessing good comprehensive benefits. Based on this, the inventors completed this invention.

[0040] The first aspect of the present invention provides a carbon-based catalyst raw material composition, the carbon-based catalyst raw material composition comprising coal gasification slag, coking coal, coal tar pitch, binder and surfactant.

[0041] The coal gasification slag of this invention contains specific amounts of carbon, silicon, aluminum, titanium, and iron, wherein the carbon exists in the form of amorphous carbon, and the silicon, aluminum, titanium, and iron exist in the forms of SiO2, Al2O3, TiO2, and Fe2O3, respectively. Specifically, the coal gasification slag contains 30-50% by weight of SiO2, 5-15% by weight of Al2O3, 1-12% by weight of Fe2O3, 0.1-2% by weight of TiO2, and 10-40% by weight of amorphous carbon.

[0042] In this invention, the inventors discovered through research that limiting the proportions of each component in the carbon-based catalyst raw material composition within a specific range can further improve the performance of the prepared carbon-based catalyst in various aspects.

[0043] In a preferred embodiment, based on the total weight of coal gasification slag, coking coal, coal tar pitch, binder and surfactant, the content of coal gasification slag is 65-75% by weight, the content of coking coal is 20-30% by weight, the content of coal tar pitch is 1-3% by weight, the content of binder is 0.5-2% by weight, and the content of surfactant is 0.1-0.5% by weight.

[0044] In this invention, the adhesive and the surfactant are not particularly limited and can be any of the various choices known to those skilled in the art.

[0045] In some embodiments, the adhesive may be selected from one or more of gelatinized starch, carboxymethyl starch, and carboxymethyl cellulose.

[0046] In some embodiments, the surfactant is selected from sodium alkylbenzene sulfonate and / or potassium perfluoroalkyl sulfonate.

[0047] In this invention, the sources of the coking coal and the coal tar pitch are not limited; they can be commercially available products or obtained through other means. Specifically, the morphology of the coal tar pitch is not limited; it can be in flake and / or block form.

[0048] In some embodiments, the coking coal is sourced from the Gulaben Coal Mine of Inner Mongolia Taixi Coal Industry Group Co., Ltd. According to GB / T212-2008 Industrial Analysis Methods for Coal, the coking coal contains 8-10% by weight of moisture, 8-10% by weight of ash, 30-40% by weight of volatile matter, and 40-50% by weight of fixed carbon.

[0049] In other embodiments, the coal tar pitch is sourced from Shenhua Ningxia Coal Industry Group Co., Ltd., and the coal tar pitch contains 8-10% moisture, 0.5-1% ash, 50-60% volatile matter, and 25-35% fixed carbon.

[0050] The second aspect of the present invention provides a method for preparing a carbon-based catalyst, wherein the carbon-based catalyst is prepared using the carbon-based catalyst raw material composition described above, and the method includes the following steps: kneading, granulating, carbonizing and activating coal gasification slag, coking coal, coal tar pitch, binder and surfactant aqueous solution.

[0051] In a specific embodiment, the method for preparing a carbon-based catalyst includes the following steps:

[0052] (1) The coal gasification slag, coking coal and coal tar pitch are made into a mixed powder, and then mixed with the binder powder to obtain the raw material powder;

[0053] (2) The raw material powder is kneaded, granulated and dried with the surfactant aqueous solution to obtain a dried product;

[0054] (3) The dried product is carbonized under oxygen-deficient conditions to obtain a carbonized product;

[0055] (4) The carbonized product is activated under oxygen-deficient conditions and in the presence of superheated steam.

[0056] In one embodiment, step (1) specifically includes: mixing coal gasification slag, coking coal and coal tar pitch in a specific ratio, then grinding them into a mixed powder by medium speed, and then mixing the mixed powder with the binder powder and stirring evenly to obtain the raw material powder.

[0057] In a preferred embodiment, in step (1), the passing rate of the mixed powder through a 250-mesh sieve is >90%, that is, the proportion of the mixed powder passing through a 250-mesh sieve is >90%.

[0058] In the method described in this invention, specifically, the kneading operation in step (2) can be performed in a kneader. In one embodiment, step (2) specifically includes: slowly adding the surfactant aqueous solution to the raw material powder, continuously stirring, and fully wetting and kneading to form a paste. In this step, adding the surfactant can reduce the surface tension of the solution, making the solution wetting more thorough.

[0059] In this invention, there is no specific limitation on the concentration of the surfactant aqueous solution. In a preferred embodiment, the concentration of the surfactant aqueous solution can be 0.5~1.5% by weight.

[0060] In a more preferred embodiment, in step (2), the amount of the surfactant aqueous solution added can be 15 to 25% by weight of the amount of the raw material powder.

[0061] In this invention, the granulation step can be carried out in a roller granulator, and the granulated product can be a cylindrical product with a diameter of 9-11 mm and a length of 20-100 mm.

[0062] In one embodiment, the drying method in step (2) can be cold air drying. Specifically, the granulated product can be dried at low temperature using a belt dryer to make it surface dry and release the internal stress formed by the high pressure during the granulation process, forming initial strength and preventing the particles from breaking irregularly due to excessive internal stress.

[0063] In a preferred embodiment, the drying temperature can be 30~50℃, and the drying time can be 10~15min.

[0064] In a specific embodiment, the carbonization conditions in step (3) include: the temperature at the feed end of the carbonization device is 380~420℃, the temperature at the discharge end is 750~850℃, and the residence time of the dried product at the discharge end of the carbonization device is 1~2h. In this step, the silicon-aluminum component can break the agglomeration of the lamellar carbon component and form a carbon-aluminum-silicon solid solution porous structure with uniform pores. This structure is the basic framework of the carbon-based catalyst. The titanium-iron metal active component also adheres to the surface of the solid solution porous structure at high temperature. Coking coal plays a skeleton role in the high-temperature carbonization process, ensuring the high-temperature sintering and forming of the granulated material. Coal tar pitch contains a large amount of polycyclic aromatic hydrocarbons, which undergo thermal condensation during the carbonization process, playing a good high-temperature bonding role.

[0065] In a preferred embodiment, the carbonization operation is carried out in a rotary kiln carbonization furnace, that is, the carbonization device is a rotary kiln carbonization furnace.

[0066] In a specific embodiment, the activation conditions of step (4) include: heating the carbonized product to 950~1050℃ under oxygen-deficient conditions, and then introducing superheated steam at 750~850℃ into the activation device for 1~2 hours. In this step, the superheated steam reacts with the fixed carbon in the carbonized product to generate water gas CO and H2, which opens the blocked pores inside the catalyst, thereby creating pores, increasing the specific surface area of ​​the catalyst, and providing a larger chemical reaction space. At the same time, the activation also forms mass transfer channels for the intrinsic titanium-iron active metal in the catalyst, ultimately forming a carbon-based catalyst with a combination of C-SiO2-Al2O3 solid solution porous structure and TiO2-Fe2O3 metal active centers.

[0067] In this invention, the carbonization device is a carbonization furnace conventionally used in the art.

[0068] In specific embodiments, the oxygen-deficient conditions in steps (3) and (4) can be the same or different. In a preferred embodiment, the oxygen-deficient conditions in step (3) include: an oxygen content of 5-10% by volume; the oxygen-deficient conditions in step (4) include: an oxygen content of 5-10% by volume.

[0069] A third aspect of the present invention provides a carbon-based catalyst prepared by the method described above. This carbon-based catalyst exhibits excellent physicochemical properties.

[0070] Specifically, the carbon-based catalyst has an ignition point ≥440℃, an iodine adsorption value ≥500mg / g, and a specific surface area ≥400m². 2 / g, abrasion resistance ≥98%, compressive strength ≥40daN, desulfurization value ≥25mg / g, denitrification rate ≥40%.

[0071] In this invention, the ignition point is tested according to GB / T 7702.9-2008; the iodine adsorption value is tested according to GB / T 7702.7-2008; the specific surface area is tested according to GB / T 7702.20-2008; the abrasion resistance is tested according to GB / T 30202.3-2013; the compressive strength is tested according to GB / T 30202.3-2013; the desulfurization value is tested according to GB / T 30202.4-2013; and the denitrification rate is tested according to GB / T 30202.5-2013.

[0072] A fourth aspect of this invention provides the application of the aforementioned carbon-based catalyst as a desulfurization and denitrification catalyst. This carbon-based catalyst is particularly suitable for industrial flue gas desulfurization and denitrification.

[0073] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0074] In the embodiments and comparative examples of this invention, the coking coal was purchased from the Gulaben Coal Mine of Inner Mongolia Taixi Coal Industry Group Co., Ltd., the semi-coke was purchased from Shaanxi Shenmu Hongjing Purified Coal Co., Ltd., the anthracite was purchased from Ningxia Coal Industry Group Co., Ltd., and the coal tar flakes were purchased from Shenhua Ningxia Coal Industry Group Co., Ltd.

[0075] Example 1

[0076] In step a of this embodiment, the coal gasification slag is derived from the coal gasification slag produced by a Texaco furnace. Its main components are 32.2% by weight of SiO2, 8.8% by weight of Al2O3, 2.5% by weight of Fe2O3, 0.5% by weight of TiO2, and 36.1% by weight of amorphous carbon.

[0077] Methods for preparing carbon-based catalysts include:

[0078] a. 230 kg of coking coal, 750 kg of coal gasification slag, and 20 kg of coal tar flakes are fed into a medium-speed mill for grinding to obtain a mixed powder. The passing rate of the mixed powder through a 250-mesh standard sieve is 91%.

[0079] b. Add 2 kg of sodium alkylbenzene sulfonate, a surfactant, to 200 kg of water to prepare a surfactant solution with a concentration of approximately 1% by weight.

[0080] c. Add the mixed powder prepared in step a to 8 kg of gelatinized starch, stir evenly with a kneader, gradually add the surfactant solution prepared in step b to the mixture, stir continuously, fully soak and knead, and prepare a paste.

[0081] d. The paste prepared in step c is fed evenly and continuously into a roller granulator through a screw feeder to form cylinders with a diameter of 9 mm and a length of 20 mm.

[0082] e. The cylinder prepared in step d is dried at low temperature and air temperature using a belt dryer to make it surface dry. The drying temperature is 35℃ and the drying time is 11 minutes.

[0083] f. The cylinder prepared in step e is fed into the inlet of a rotary kiln carbonization furnace for oxygen-deficient carbonization. The oxygen content is 6% by volume, the feed end temperature is 390℃, the discharge end temperature is 760℃, and the discharge end residence time is 1.2h.

[0084] g. Cool the material prepared in step f to 25°C, and then send it into the Sleip activation furnace through the material conveying system. Heat it to 960°C under 6% volume oxygen-deficient conditions, and at the same time introduce superheated steam at 760°C into the side gas channel of the activation furnace. Activate for 1.6 hours to obtain carbon-based catalyst C-1.

[0085] Testing revealed that the carbon-based catalyst C-1 is a combination of a porous C-SiO2-Al2O3 solid solution structure and a TiO2-Fe2O3 metal active center.

[0086] Example 2

[0087] In step a of this embodiment, the coal gasification slag is derived from the coal gasification slag produced by a four-nozzle furnace. Its main components are 32.7% by weight of SiO2, 9.6% by weight of Al2O3, 9.8% by weight of Fe2O3, 1.3% by weight of TiO2, and 17.8% by weight of amorphous carbon.

[0088] Methods for preparing carbon-based catalysts include:

[0089] a. 230 kg of coking coal, 750 kg of coal gasification slag, and 20 kg of coal tar flakes are fed into a medium-speed mill for grinding to obtain a mixed powder. The mixed powder has a 95% passing rate through a 250-mesh standard sieve.

[0090] b. Add 2 kg of potassium perfluoroalkyl sulfonate, a surfactant, to 200 kg of water to prepare a surfactant solution with a concentration of approximately 1% by mass.

[0091] c. Add the mixed powder prepared in step a to 10 kg of carboxymethyl starch, stir evenly using a kneader, gradually add the surfactant solution prepared in step b to the mixture, stir continuously, fully soak and knead, and prepare a paste.

[0092] d. The paste prepared in step c is fed evenly and continuously into a roller granulator through a screw feeder to form cylinders with a diameter of 11 mm and a length of 90 mm.

[0093] e. The cylinder prepared in step d is dried at low temperature and air temperature using a belt dryer to make its surface dry. The drying temperature is 45℃ and the time is 15 minutes.

[0094] f. The cylinder prepared in step e is fed into the inlet of a rotary kiln carbonization furnace for oxygen-deficient carbonization. The oxygen content is 9% by volume, the feed end temperature is 410℃, the discharge end temperature is 830℃, and the discharge end residence time is 1.8h.

[0095] g. Cool the material prepared in step f to 25°C, and then send it into the Sleip activation furnace through the material conveying system. Heat it to 1030°C under 9% volume oxygen-deficient conditions, and at the same time introduce superheated steam at 830°C into the side gas channel of the activation furnace. Activate for 1.9 hours to obtain carbon-based catalyst C-2.

[0096] Testing revealed that the carbon-based catalyst C-2 is a combination of a porous C-SiO2-Al2O3 solid solution structure and a TiO2-Fe2O3 metal active center.

[0097] Example 3

[0098] In step a of this embodiment, the coal gasification slag is derived from the coal gasification slag produced by a GSP furnace. Its main components are 47.6% by weight of SiO2, 13.7% by weight of Al2O3, 6.1% by weight of Fe2O3, 1.0% by weight of TiO2, and 16.0% by weight of amorphous carbon.

[0099] Methods for preparing carbon-based catalysts include:

[0100] a. 230 kg of coking coal, 750 kg of coal gasification slag, and 20 kg of coal tar flakes are fed into a medium-speed mill for grinding to obtain a mixed powder. The passing rate of the mixed powder through a 250-mesh standard sieve is 92%.

[0101] b. Add 1 kg each of sodium alkylbenzene sulfonate and potassium perfluoroalkyl sulfonate to 200 kg of water to prepare a surfactant solution with a concentration of about 1% by weight.

[0102] c. Add the mixed powder prepared in step a to 8 kg of carboxymethyl cellulose, stir evenly using a kneader, gradually add the surfactant solution prepared in step b to the mixture, stir continuously, fully soak and knead, and prepare a paste.

[0103] d. The paste prepared in step c is fed evenly and continuously into a roller granulator through a screw feeder to form cylinders with a diameter of 10 mm and a length of 60 mm.

[0104] e. The cylinder prepared in step d is dried at low temperature and air temperature using a belt dryer to make its surface dry. The drying temperature is 40℃ and the time is 12 minutes.

[0105] f. The cylinder prepared in step e is fed into the inlet of a rotary kiln carbonization furnace for oxygen-deficient carbonization. The oxygen content is 7% by volume, the feed end temperature is 400℃, the discharge end temperature is 800℃, and the discharge end residence time is 1.5h.

[0106] g. Cool the material prepared in step f to 25°C, and then send it into the Sleip activation furnace through the material conveying system. Heat it to 1000°C under 7% volume oxygen-deficient conditions, and at the same time introduce superheated steam at 800°C into the side gas channel of the activation furnace. Activate for 1.7 hours to obtain carbon-based catalyst C-3.

[0107] Testing revealed that the combination of the porous structure of the C-SiO2-Al2O3 solid solution and the active metal centers of TiO2-Fe2O3...

[0108] The coal-based activated coke prepared in the following comparative examples meets the standard requirements of "GB / T 30201-2013 Coal-based Granular Activated Carbon for Desulfurization and Denitrification".

[0109] Comparative Example 1

[0110] (1) 200 kg of coking coal, 750 kg of semi-coke, 30 kg of anthracite, and 20 kg of coal tar flakes were fed into a medium-speed mill for grinding to obtain a mixed powder. The passing rate of the mixed powder through a 250-mesh standard sieve was 92%.

[0111] (2) Add 2 kg of sodium alkylbenzene sulfonate, a surfactant, to 200 kg of water to prepare a surfactant solution with a concentration of 1% by weight;

[0112] (3) Add the mixed powder prepared in step (1) to 10 kg of carboxymethyl cellulose binder, stir evenly with a kneader, gradually add the surfactant solution prepared in step (2) to the mixture, stir continuously, fully soak and knead, and prepare a paste.

[0113] (4) The paste prepared in step (3) is fed into a roller granulator evenly and continuously through a screw feeder to form a cylinder with a diameter of 10 mm and a length of 40 mm.

[0114] (5) The cylinder prepared in step (4) is dried by low temperature air cooling through a belt dryer to make it surface dry. The drying temperature is 40℃ and the time is 12 minutes.

[0115] (6) The cylinder prepared in step (5) is fed into the inlet of a rotary kiln carbonization furnace for oxygen-deficient carbonization. The oxygen content is 7% by volume, the feed end temperature is 400℃, the discharge end temperature is 800℃, and the discharge end residence time is 1.5h.

[0116] (7) The material prepared in step (6) is cooled down to 20°C and then fed into the Sleip activation furnace through the material conveying system. It is heated to 1000°C in a 7% volume oxygen-deficient environment. At the same time, superheated steam at 800°C is introduced into the side gas channel of the activation furnace and activated for 1.8 hours to obtain desulfurized and denitrified activated coke B-1.

[0117] Comparative Example 2

[0118] The method of Comparative Example 1 was implemented, except that the coal blending ratio in step (1) was changed to 230 kg of coking coal, 700 kg of semi-coke, 50 kg of anthracite, and 20 kg of coal tar pitch flakes to obtain desulfurized and denitrified activated coke B-2.

[0119] Comparative Example 3

[0120] The method of Comparative Example 1 was implemented, except that the coal blending ratio in step (1) was changed to 290 kg of coking coal, 590 kg of semi-coke, 100 kg of anthracite, and 20 kg of coal tar pitch flakes to obtain desulfurized and denitrified activated coke B-3.

[0121] Test case

[0122] The following describes the beneficial effects of preparing carbon-based desulfurization and denitrification catalysts according to the technical solution of this invention, based on the examples C-1~C-3 and comparative examples B-1~B-3, from three aspects: catalyst physicochemical properties, energy consumption in the preparation process, and industrial operation performance.

[0123] (1) Physicochemical properties

[0124] The physicochemical properties of the test examples samples C-1~C-3 and the comparative examples samples B-1~B-3 were tested, and the results are shown in Table 1. Details are as follows:

[0125] Compressive strength: Tested according to GB / T 30202.3-2013;

[0126] Abrasion resistance: Tested according to GB / T 30202.3-2013;

[0127] Ignition point: Tested according to GB / T 7702.9-2008;

[0128] Iodine adsorption value: Tested according to GB / T 7702.7-2008;

[0129] Specific surface area: tested according to GB / T 7702.20-2008;

[0130] Micropore (pore size <2nm) volume: measured using a pore size analyzer (Kunta NOVA touch LX2);

[0131] Mesopore (pore size 2nm~50nm) volume: measured by pore size analyzer (Kunta NOVA touch LX2);

[0132] Desulfurization value: Tested according to GB / T 30202.4-2013, the simulated flue gas composition is: sulfur dioxide concentration 2917 mg / m³. 3The oxygen concentration was 6.4% by volume, the water vapor concentration was 9.8% by volume, and nitrogen was used as the equilibrium gas. The reaction temperature was controlled at 120±5℃, and the space velocity under standard conditions was 3670 h⁻¹. -1 ;

[0133] Denitrification rate: Tested according to GB / T 30202.5-2013, where the simulated flue gas composition is: nitric oxide concentration 268 mg / m³. 3 The ammonia concentration was 152 mg / m³. 3 The oxygen volume fraction was 6.4%, the water vapor volume fraction was 8.0%, nitrogen was used as the equilibrium gas, the reaction temperature was 120±5℃, and the space velocity under standard conditions was 400 h⁻¹. -1 .

[0134] Table 1

[0135]

[0136] As can be observed from Table 1, the carbon-based catalyst prepared in this invention, sample C-2, compared to C-1, has a higher silicon-aluminum:carbon ratio in its feed gasification slag. The silicon-aluminum component has a better dispersion effect on the agglomeration of the layered carbon components. Therefore, its specific surface area and micropore volume are higher than those of C-1. In addition, the iron-titanium active metal content in the feed gasification slag of C-2 is higher, so the denitrification rate of C-2 is significantly higher than that of C-1. Compared to sample C-1, sample C-2 has a higher silicon-aluminum:carbon ratio. The silicon-aluminum component has a better dispersion effect on the agglomeration of the layered carbon components, resulting in a higher micropore volume. However, its mesopore volume is lower than that of C-1, and its desulfurization value is also slightly lower than that of C-1. This is because, in the desulfurization reaction, the mesopores play a role in storing the product sulfuric acid, which can increase the desulfurization value of the catalyst. Therefore, although the micropore volume of C-2 is slightly larger, the mesopore volume is smaller. Under the combined effect, the desulfurization value of C-2 is still lower than that of C-1. The gasification slag from the feedstock of C-2 has a lower content of carbon with a low ignition point. After dispersion with silicon and aluminum components, the catalyst prepared has a higher ignition point than that of C-1. The coal gasification slag from the feedstock of C-2 also has a lower content of carbon with low hardness. After dispersion with silicon and aluminum components, the mechanical strength (wear resistance and compressive strength) of C-2 is higher than that of C-1.

[0137] As can be observed from Table 1, the carbon-based catalyst prepared in this invention, sample C-3, has a higher content of silicon and aluminum in its raw material coal gasification slag compared to C-2. The silicon and aluminum components have a better effect on the agglomeration and dispersion of the layered carbon components, resulting in a higher specific surface area and micropore volume than C-2. However, the content of iron and titanium active metal components in its raw material coal gasification slag is lower than that of C-2. Under the combined effect, its denitrification rate is not significantly different from that of C-2. The mesopore volume of C-3 is lower than that of C-2, and its desulfurization value is slightly lower than that of C-2. This is because, in the desulfurization reaction, the mesopores play a role in storing the product sulfuric acid, which can increase the desulfurization value of the catalyst. Therefore, although the micropore volume of C-3 is slightly larger, its mesopore volume is smaller, and under the combined effect, the desulfurization value of C-3 is still lower than that of C-2. In the gasification slag of C-3, the content of carbon with low ignition point is not significantly different from that of C-2, but the silicon-aluminum content is higher, which has a better dispersion effect on the layered carbon components with low ignition point, and its ignition point is slightly higher than that of C-2. In the gasification slag of C-3, the content of carbon with low hardness is not significantly different from that of C-2, but the silicon-aluminum content is higher, which has a better dispersion effect on the layered carbon components with low hardness, and its mechanical strength (wear resistance and compressive strength) is slightly higher than that of C-2.

[0138] As can be observed from Table 1, the carbon-based catalysts prepared in this invention, compared to activated coke samples B-1-B-3 prepared according to GB / T30201, exhibit higher specific surface area, mesopore volume, and micropore volume due to the silicon-aluminum composition in the coal gasification slag of C-1-C-3, which disrupts the agglomeration of the lamellar carbon components with low ignition point and low hardness. Furthermore, samples C-1-C-3 possess endogenous iron-titanium metal active centers, resulting in significantly higher desulfurization and denitrification rates compared to samples B-1-B-3. In C-1-C-3, the content of carbon with low ignition point is lower, leading to a significantly higher ignition point than samples B-1-B-3. Similarly, the lower content of carbon with low hardness in C-1-C-3 results in significantly higher mechanical strength (wear resistance and compressive strength) compared to samples B-1-B-3. Therefore, the carbon-based catalyst prepared in this invention outperforms the activated coke prepared in the comparative example.

[0139] (2) Energy consumption in the preparation process of carbon-based catalysts

[0140] The energy consumption of the preparation process in the examples and comparative examples is shown in Table 2. The binder and surfactant are not included in the energy consumption statistics because the amount used is extremely small.

[0141] Table 2

[0142]

[0143] As can be seen from Table 2, for the examples and comparative examples, on the premise that the total amount of raw materials (1000 kg) is the same, there is no obvious difference in the secondary energy consumption, but there is an obvious difference in the primary energy source (coal-based raw materials). Since the samples C-1 to C-3 in the examples use coal gasification slag as the main raw material, which belongs to the utilization of solid waste, the energy consumption of the primary energy source is not included. Therefore, the primary energy consumption of the samples C-1 to C-3 in the examples is significantly reduced. For every 1000 kg of raw materials, the ratio of the primary energy consumption of the samples C-1 to C-3 in the examples to that of B-1 to B-3 is less than 24%. If the final products are examined, the ratio of the total energy consumption per ton of products of the samples C-1 to C-3 in the examples to that of the comparative example samples B-1 to B-3 is less than 26%. It can be observed from Table 2 that the energy consumption of the comparative example samples B-1 to B-3 is lower than the advanced value (2 t standard coal / t product) specified in GB29994-2013. If the energy consumption of the samples C-1 to C-3 in the examples is compared with the advanced energy consumption value specified in GB29994-2013, the ratio is less than 24%.

[0144] (3)Industrial application performance

[0145] A 265m 2 activated coke desulfurization and denitrification device supporting a belt type sintering machine, with the flue gas temperature being 110 - 150 °C and the flue gas working condition flow rate being 130 - 150×10 4 m 3 / h, the SO2 concentration at the inlet of the device is 800 - 1200 mg / m 3 , and the NO X concentration at the inlet of the device is 150 - 300 mg / m 3 . The ammonia water used for denitrification has a mass concentration of 20%, and the ammonia water injection flow rate is 0.6 - 0.9 t / h.

[0146] The activated coke filling amount of this desulfurization and denitrification tower is 4092 t. The activated coke moves continuously from top to bottom in the desulfurization and denitrification tower, continuously contacts with the flue gas. Finally, the activated coke with saturated adsorption is discharged from the bottom of the device and sent to the regeneration device. After the regeneration device desorbs the SO2 adsorbed in the activated coke, the desorbed activated coke is returned to the top of the desulfurization and denitrification tower and participates in the desulfurization and denitrification reaction again. In this device, the hourly circulation amount of the activated coke is 18 t / h, and the daily circulation amount is 432 t / d. During the circulation process, the particles with a particle size less than 1.5 mm are removed by a vibrating sieve and no longer participate in the activated coke circulation. These small particles removed by the vibrating sieve are counted as the operating loss of the activated coke, and the statistical unit is t / d.

[0147] The samples C-1 to C-3 in the examples and the samples B-1 to B-3 in the comparative examples are applied to this industrial device to investigate their industrial application performance. As shown in Table 3, the data in the table are the average values of the 168-hour continuous operation of the device.

[0148] Table 3

[0149]

[0150] As shown in Table 3, the material operating losses are consistent with the trend in Table 2. Higher mechanical strength (compressive strength, abrasion resistance) results in lower material operating losses. The losses of the example samples C-1 to C-3 are significantly better than those of the comparative samples B-1 to B-3. For the three example samples, the material operating losses are C-1 > C-2 > ​​C-3. Regarding desulfurization efficiency, the difference between the example samples C-1 to C-3 and the comparative samples B-1 to B-3 is very small. This is because, for the activated coke desulfurization and denitrification method, the desulfurization reaction of activated coke takes precedence over the denitrification reaction. Even if the activated coke's desulfurization effect is poor, the portion of activated coke that should participate in the denitrification reaction will still participate, compensating for the poor desulfurization effect of the device. As for denitrification efficiency, because the example samples C-1 to C-3 have a larger specific surface area and micropore area, and contain endogenous iron-titanium active metal components, their denitrification efficiency is significantly higher than that of the comparative samples B-1 to B-3.

[0151] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A carbon-based catalyst feedstock composition, characterized in that, The carbon-based catalyst feedstock composition contains coal gasification slag, coking coal, coal tar pitch, binder, and surfactant. The coal gasification slag contains 30-50% by weight SiO2, 5-15% by weight Al2O3, 1-12% by weight Fe2O3, 0.1-2% by weight TiO2 and 10-40% by weight amorphous carbon. Based on the total weight of coal gasification slag, coking coal, coal tar pitch, binder, and surfactant, the content of coal gasification slag is 65-75% by weight, coking coal is 20-30% by weight, coal tar pitch is 1-3% by weight, binder is 0.5-2% by weight, and surfactant is 0.1-0.5% by weight. The adhesive is selected from one or more of gelatinized starch, carboxymethyl starch and carboxymethyl cellulose; The surfactant is selected from sodium alkylbenzene sulfonate and / or potassium perfluoroalkyl sulfonate.

2. A method for preparing a carbon-based catalyst, characterized in that, The carbon-based catalyst is prepared using the carbon-based catalyst raw material composition described in claim 1. The method includes the following steps: kneading, granulating, carbonizing, and activating coal gasification slag, coking coal, coal tar pitch, binder, and surfactant aqueous solution.

3. The method according to claim 2, characterized in that, The method includes the following steps: (1) The coal gasification slag, coking coal and coal tar pitch are made into a mixed powder, and then mixed with the binder powder to obtain the raw material powder; (2) The raw material powder is kneaded, granulated and dried with the surfactant aqueous solution to obtain a dried product; (3) The dried product is carbonized under oxygen-deficient conditions to obtain a carbonized product; (4) The carbonized product is activated under oxygen-deficient conditions and in the presence of superheated steam.

4. The method according to claim 3, characterized in that, In step (1), the proportion of the mixed powder passing through a 250-mesh sieve is >90%.

5. The method according to claim 2, characterized in that, The concentration of the surfactant aqueous solution is 0.5~1.5 by weight.

6. The method according to claim 3, characterized in that, In step (2), the amount of the surfactant aqueous solution added is 15 to 25% by weight of the amount of the raw material powder.

7. The method according to claim 3, characterized in that, The drying method is: cold air drying.

8. The method according to claim 7, characterized in that, The drying conditions include a temperature of 30-50°C and a time of 10-15 minutes.

9. The method according to claim 3, characterized in that, The carbonization conditions in step (3) include: the temperature at the feed end of the carbonization device is 380~420℃, the temperature at the discharge end is 750~850℃, and the residence time of the dried product at the discharge end of the carbonization device is 1~2h.

10. The method according to claim 3, characterized in that, The activation conditions in step (4) include: heating the carbonized product to 950~1050°C under oxygen-deficient conditions, then introducing superheated steam at 750~850°C into the activation device for 1~2 hours.

11. The method according to claim 3, characterized in that, In steps (3) and (4), the oxygen-deficient conditions include an oxygen content of 5-10% by volume.

12. A carbon-based catalyst prepared by the method according to any one of claims 2-11.

13. The carbon-based catalyst according to claim 12, characterized in that, The carbon-based catalyst has an ignition point ≥440℃, an iodine adsorption value ≥500mg / g, and a specific surface area ≥400m². 2 / g, abrasion resistance ≥98%, compressive strength ≥40daN, desulfurization value ≥25mg / g, denitrification rate ≥40%.

14. The use of the carbon-based catalyst according to claim 12 or 13 as a desulfurization and denitrification catalyst.

Images