Weathered coal-based sodium / potassium humate fire coal catalyst as well as preparation and application thereof

Abstract

The invention discloses a preparation method of an environment-friendly, easily-available, sulfur-fixing and coal-saving catalyst. The catalyst is characterized by comprising weathered coal, tap water, potassium humate and sodium humate. The preparation method comprises the following steps: adding 20-80 parts of sodium humate, 80-20 parts of potassium humate, 20-30 parts of calcium chloride, 1-4 parts of nickel nitrate hexahydrate, 25-35 parts of sodium nitrate, 6-9 parts of copper nitrate and 7-9 parts of cerous nitrate to 1000mL of tap water into a reaction container, and fully stirring until dissolving to obtain the coal-saving catalyst. The optimal ratio of the catalyst to raw coal is that the addition amount of the catalyst is 1mL per 10Kg of raw coal, and the coal combustion efficiency and the sulfur fixation effect are obviously improved.

Description

Technical Field

[0001] The present invention relates to the preparation of an environmentally friendly, easy-to-obtain, sulfur-fixing and coal-saving catalyst, and in particular to the preparation of a weathered coal-based sodium / potassium humate coal-fired catalyst. Background Art

[0002] The direct combustion of coal is inefficient and costly, which not only wastes resources but also causes environmental pollution. In order to improve the efficiency and cost-effectiveness of coal, adding a composite catalyst during its combustion process can not only reduce the ignition temperature, promote burnout, and reduce the apparent activation energy to achieve the purpose of combustion-supporting, but also effectively remove SO2 in the flue gas. Studies have shown that alkali metals, especially sodium and potassium salts, can effectively improve the combustion efficiency of coal as catalysts. This is because during the rapid pyrolysis of coal, the addition of sodium salts makes the surface of the pyrolysis coke rough, stabilizes the surface oxygen-containing functional groups, inhibits the graphitization process of the pyrolysis coke, and increases the crosslinking density and surface substituents. Part of the sodium is retained in the coke after rapid pyrolysis, showing a good catalytic effect. Potassium ions can participate in the intermediate steps of the combustion reaction, change the reaction pathway, and thus reduce the activation energy of the reaction. Potassium ions can be adsorbed on the carbon surface, making it easier for oxygen molecules to dissociate and adsorb on the carbon surface to form active oxygen species (such as atomic oxygen). These active oxygen species react more easily with carbon, which accelerates the rate of the combustion reaction.

[0003] Chinese patent CN117025276A discloses a coal combustion promoter, wherein the promoter is sodium hydroxide. The addition of sodium hydroxide to the combustion promoter of the present invention dissolves in water, which releases a large amount of heat, effectively accelerating the reaction rate between carbon and oxygen in coal and promoting coal combustion. Chinese patent CN101775323A discloses a method for preparing a coal combustion promoter. The present invention generates humic acid with a lower ignition point by adding sodium acetate, thereby promoting coal combustion. Chinese patent CN201410361006.1 discloses a multifunctional coal-saving and efficiency-enhancing additive, in which the addition of potassium ions effectively promotes combustion of different types of coal and reduces SO2, NO X emissions. In addition, studies have shown that when sodium ions and potassium ions are added at the same time, the emission of nitrogen oxides can be reduced by 20-30% compared to when only one ion is added. Based on this, the present invention uses humic acid alkali metals instead of inorganic metal salts to prepare a coal combustion catalyst. Xinjiang is rich in weathered coal, and the abundant weathered coal is the guarantee for obtaining sufficient humic acid salts. And sodium humate and potassium humate, as natural substances, are more environmentally friendly than industrial-grade inorganic salts. In addition, humic acid substances produce relatively few pollutants during the combustion process. Therefore, in order to solve the above problems, the present application provides a coal-saving catalyst, and further provides a preparation method. Summary of the invention

[0004] The purpose of the present invention is to develop a method for preparing a catalyst which is environmentally friendly, readily available, sulfur-fixing and coal-saving.

[0005] The purpose of the present invention is achieved through the following technical solutions.

[0006] A method for preparing an environmentally friendly, readily available, sulfur-fixing, coal-saving catalyst, characterized in that the method comprises the following process steps:

[0007] (1) Preparation of potassium humate: First, weathered coal is crushed and sieved (80-100 mesh), and 5 g of weathered coal is added to 30 mL of an aqueous solution containing 0.45 g of potassium hydroxide. After magnetic stirring at room temperature for 1 hour, the potassium humate solution is collected by filtration. The pH is adjusted to 2-3 with HCl, and after solid humic acid is precipitated, the filtrate is washed with water to a pH of 5-6, and the solid is dried to obtain potassium-containing humic acid.

[0008] (2) Extraction of sodium humate: First, the weathered coal is crushed and sieved (80-100 mesh), 5g of weathered coal is mixed with 50mL of 1% sodium hydroxide aqueous solution and stirred for 2h to generate a sodium humate solution. The pH is adjusted to 2-3 with HCl, and after solid humic acid is precipitated, the filtrate is washed with water to a pH of 5-6, and then the solid is dried to obtain sodium-containing humic acid.

[0009] (3) An environmentally friendly, readily available, sulfur-fixing, coal-saving catalyst: 20-80 parts of sodium humate, 80-20 parts of potassium humate, 20-30 parts of calcium chloride, 1-4 parts of nickel nitrate hexahydrate, 25-35 parts of sodium nitrate, 6-9 parts of copper nitrate, and 7-9 parts of cerium nitrate are added to a reaction vessel, and the sum of the components is 100%. After mixing evenly, the mixture is dissolved in 200% water to obtain an environmentally friendly, readily available, sulfur-fixing, coal-saving catalyst. The amount of the catalyst added is 0.01% of the mass ratio of the raw coal, and the sulfur emission of the flue gas from the coal combustion is reduced, which has a significant environmental protection effect, and can significantly improve the combustion efficiency, save 20%-30% of the coal combustion, and the sulfur-fixing efficiency is 25-40%.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] (1) Xinjiang is rich in weathered coal. The present invention extracts humate from weathered coal, which has the advantages of wide source and easy acquisition;

[0012] (2) Sodium humate can promote the formation of hydrogen bonds in coal and stabilize ether groups, thereby slowing down the oxidation process of coal and improving combustion efficiency;

[0013] (3) Potassium humate increases the number of crosslinks between aromatic and hydrogenated aromatic structural units in coal, thereby increasing the molecular weight of coal, reducing fluidity during heat treatment, and further reducing the migration of planar regions, preventing them from arranging to form anisotropic coke materials, thus playing a role in saving coal;

[0014] (4) The combined effect of sodium humate and potassium humate produces a 1+1>2 effect in reducing the ignition point of coal, further improving the coal-saving effect;

[0015] (5) Use humates instead of inorganic salts during coal combustion to reduce corrosion to equipment during the combustion process;

[0016] (6) Traditional calcium-based sulfur fixers are prone to sintering at high temperatures, but using humate to fix sulfur can solve this problem. DETAILED DESCRIPTION

[0017] Preparation of potassium humate used in the following examples: First, Xinjiang weathered coal is crushed and sieved (80-100 mesh), and 5 g of weathered coal is added to 30 mL of an aqueous solution containing 0.45 g of potassium hydroxide, and the potassium humate solution is collected by filtration after magnetic stirring for 1 h at room temperature. The pH is adjusted to 2-3 (here 2.6) with 36% HCl, and after solid potassium humate is precipitated, the filtrate is washed with water to a pH of 5-6 (here 5.7), and the solid is dried to obtain potassium-containing potassium humate with a yield of 65%, wherein the potassium mass content exceeds 17%.

[0018] The extraction of sodium humate used in the following examples is as follows: First, Xinjiang weathered coal is crushed and sieved (80-100 mesh), 5g of weathered coal is mixed with 50mL of 1% sodium hydroxide aqueous solution, stirred for 2h, and a sodium humate solution is generated. The pH is adjusted to 2-3 (here 2.4) with 36% HCl, and after solid sodium humate is precipitated, the filtrate is washed with water to a pH of 5-6 (here 5.5), and the solid is dried to obtain sodium humate containing sodium, with a yield of 68%, wherein the sodium content exceeds 10%.

[0019] The weathered coal is produced in Xinjiang, and the humic acid content in the weathered coal is 50-70% (here 67.3%);

[0020] Example 1

[0021] Coal-saving catalyst: Add 50g of sodium humate, 40g of potassium humate, 26g of calcium chloride, 3g of nickel nitrate hexahydrate, 30g of sodium nitrate, 8g of copper nitrate, and 8g of cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0022] Example 2

[0023] Coal-saving catalyst: Add 40g sodium humate, 50g potassium humate, 26g calcium chloride, 3g nickel nitrate hexahydrate, 30g sodium nitrate, 8g copper nitrate, and 8g cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0024] Example 3

[0025] Coal-saving catalyst: Add 30g sodium humate, 60g potassium humate, 26g calcium chloride, 3g nickel nitrate hexahydrate, 30g sodium nitrate, 8g copper nitrate, and 8g cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0026] Example 4

[0027] Coal-saving catalyst: Add 20g sodium humate, 70g potassium humate, 26g calcium chloride, 3g nickel nitrate hexahydrate, 30g sodium nitrate, 8g copper nitrate, and 8g cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0028] Example 5

[0029] Coal-saving catalyst: Add 60g of sodium humate, 30g of potassium humate, 26g of calcium chloride, 3g of nickel nitrate hexahydrate, 30g of sodium nitrate, 8g of copper nitrate, and 8g of cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0030] Example 6

[0031] Coal-saving catalyst: Add 70g of sodium humate, 20g of potassium humate, 26g of calcium chloride, 3g of nickel nitrate hexahydrate, 30g of sodium nitrate, 8g of copper nitrate, and 8g of cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0032] Example 7

[0033] Coal-saving catalyst: Add 10g sodium humate, 80g potassium humate, 26g calcium chloride, 3g nickel nitrate hexahydrate, 30g sodium nitrate, 8g copper nitrate, and 8g cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0034] Example 8

[0035] Coal-saving catalyst: Add 5g sodium humate, 85g potassium humate, 26g calcium chloride, 3g nickel nitrate hexahydrate, 30g sodium nitrate, 8g copper nitrate, and 8g cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0036] Example 9

[0037] Coal-saving catalyst: Add 85g of sodium humate, 5g of potassium humate, 26g of calcium chloride, 3g of nickel nitrate hexahydrate, 30g of sodium nitrate, 8g of copper nitrate, and 8g of cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0038] Example 10

[0039] Coal-saving catalyst: Add 80g of sodium humate, 10g of potassium humate, 26g of calcium chloride, 3g of nickel nitrate hexahydrate, 30g of sodium nitrate, 8g of copper nitrate, and 8g of cerium nitrate to a reaction container and dilute to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0040] Comparative Example 1

[0041] The specific implementation process and conditions of this comparative example are the same as those of Example 1, except that sodium humate is replaced by a NaCl aqueous solution containing the same Na content.

[0042] Comparative Example 2

[0043] The specific implementation process and conditions of this comparative example are the same as those of Example 1, except that potassium humate is replaced by a KCl aqueous solution containing the same K content.

[0044] Comparative Example 3

[0045] Coal-saving catalyst: 40g potassium humate, 26g calcium chloride, 3g nickel nitrate hexahydrate, 30g sodium nitrate, 8g copper nitrate, 8g cerium nitrate are diluted to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0046] Comparative Example 4

[0047] Coal-saving catalyst: 50g sodium humate, 26g calcium chloride, 3g nickel nitrate hexahydrate, 30g sodium nitrate, 8g copper nitrate, 8g cerium nitrate are diluted to 1L of tap water. Stir thoroughly until dissolved to obtain a coal-saving catalyst.

[0048] Performance Evaluation

[0049] The weathered coal-based sodium / potassium humate catalysts prepared in Examples 1-10 and Comparative Examples 1-4 (coal samples without additives as blank controls) were respectively applied to the same mass of coal combustion experiments to measure the ignition point, combustion efficiency and sulfur content of the emissions. The ignition point of the coal sample without additives was 385°C.

[0050] The combustion efficiency is measured with reference to the national standard GB / T10180-2017 "Industrial Boiler Thermal Performance Test Procedure": This standard specifies the detailed method for testing the thermal efficiency of industrial boilers. The combustion efficiency is determined by the positive balance method (directly measuring the input heat and output heat to calculate the efficiency) and the reverse balance method (calculating the efficiency by measuring various heat losses). Compare with the blank sample of the coal sample without adding catalyst.

[0051] The ignition point of the sample was analyzed according to the thermogravimetric curve: the intersection of the tangent line at the horizontal position before the TG step and the tangent line at the inflection point of the curve was the ignition point of the sample.

[0052] The details are as follows: weigh 100g of coal powder and disperse it in 500mL of tap water, then add 1mL of the evenly dispersed catalyst solution, stir evenly, and let it stand for 12h; dry it at 80℃ (7-8h) to obtain a coal sample. Take 100mg of coal sample (the sample without coal-saving agent is the control sample, as a blank control), starting temperature: 30℃; end temperature: 900℃; heating rate: 10℃ / min, air atmosphere, flow rate is 100mL / min, thermogravimetric analysis sample amount: 5-10mg.

[0053] The national standard for testing the sulfur content of coal during combustion in a boiler is GB / T 214-2007 "Determination of total sulfur in coal". The high-temperature combustion neutralization method is used, and the specific operation is as follows:

[0054] The coal sample is burned in a high-temperature oxygen flow to convert the sulfur in the coal into sulfur dioxide and sulfur trioxide, which are then absorbed by a hydrogen peroxide solution. The generated sulfuric acid is neutralized and titrated with a standard sodium hydroxide solution. The mass content of total sulfur emitted in the coal is calculated based on the consumption of the standard sodium hydroxide solution.

[0055] The coal sample (100g of coal powder is weighed and dispersed in 500mL of tap water, followed by adding 1mL of evenly dispersed catalyst solution, stirring evenly, and standing for 12h; then drying at 80℃ (7-8h) to obtain the coal sample. The sample without adding coal-saving agent is the control sample, which serves as a blank control) is burned in an oxygen flow at 1200℃ and kept at 1200℃±5℃ to convert the sulfur in the coal into sulfur dioxide and sulfur trioxide, which are then absorbed by hydrogen peroxide solution. The generated sulfuric acid is neutralized and titrated with a standard sodium hydroxide solution, and the mass content of total sulfur emitted in the coal is calculated based on the consumption of the standard sodium hydroxide solution.

[0056] The results show that the weathered coal-based sodium / potassium humate coal-fired catalysts prepared in Examples 1-6 can significantly improve the combustion efficiency and sulfur emissions of coal compared to Examples 7-8, and the effects are better than those of the catalysts in Comparative Examples 1 and 2.

[0057]

[0058]

[0059] It can be seen from Examples 1 to 10 and Comparative Examples 1 to 6 that the present invention provides a weathered coal-based sodium / potassium humate coal-fired catalyst and a preparation method thereof. The coal-saving catalyst prepared in this application has good effects of promoting coal combustion, reducing combustion time, improving combustion efficiency, and reducing pollutant emissions, and has broad development prospects.

[0060] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the protection scope determined by the claims of the present invention.

Claims

1. A weathered coal-based sodium / potassium humate coal-fired catalyst, characterized in that: The following steps are involved: The multifunctional coal-burning catalyst and the solid coal-saving catalyst are composed of the following raw materials in parts by weight: 20 to 80 parts (preferably 40 to 50 parts) of weathered coal-based sodium humate, 80 to 20 parts (preferably 50 to 40 parts) of weathered coal-based potassium humate, 20 to 30 parts (preferably 24 to 28 parts) of calcium chloride, 1 to 4 parts (preferably 2 to 3 parts) of nickel nitrate hexahydrate, 25 to 35 parts (preferably 28 to 32 parts) of sodium nitrate, 6 to 9 parts (preferably 7 to 8 parts) of copper nitrate, and 7 to 9 parts (preferably 7.5 to 8.5 parts) of cerium nitrate; Alternatively, the above-mentioned material before or after mixing (or solid coal-saving catalyst) is added to an appropriate amount of water (based on 100g of the above-mentioned material before or after mixing, the amount of water is 600-800mL, preferably 600-650mL), and stirred until it is evenly dispersed to obtain a liquid coal-saving catalyst.

2. The catalyst according to claim 1, characterized in that The preparation process of weathered coal-based sodium humate is as follows: firstly, the weathered coal is crushed and sieved (80-100 meshes), 5g of weathered coal is mixed with 30-80mL of a sodium hydroxide aqueous solution with a mass concentration of 0.5-2%, stirred for 1-4h, and the solution is collected by solid-liquid separation; pH is adjusted to 2-3 with HCl with a mass concentration of 20-36%, sodium humate is precipitated, the pH of the filtrate is washed with water to 5-6, and then the solid is dried, and sodium humate with a sodium content of 8-12% is obtained after drying.

3. The catalyst according to claim 1, characterized in that The preparation process of weathered coal-based potassium humate is as follows: firstly, the weathered coal is crushed and sieved (80-100 meshes), and 5 g of weathered coal is added into 20-40 mL of an aqueous solution containing 0.4-0.5 g of potassium hydroxide, and stirred at room temperature for 0.5-2 hours, and the solution is collected by solid-liquid separation; the pH is adjusted to 2-3 with HCl having a mass concentration of 20-36%, sodium humate is precipitated, the filtrate is washed with water to a pH of 5-6, and then the solid is dried to obtain potassium humate containing 15-19% potassium by mass.

4. The catalyst according to claim 2 or 3, characterized in that Weathered coal comes from Xinjiang, and the humic acid content in weathered coal is 50-70%.

5. The catalyst according to claim 1, characterized in that The optimal mass ratio of sodium humate to potassium humate is 4-5:4-5.

6. A method for preparing the catalyst according to any one of claims 1 to 5, characterized in that: Mix the materials required for the catalyst according to any one of claims 1 to 5; Or the materials required for the catalyst according to any one of claims 1 to 5 are mixed before or after being added to an appropriate amount of water (based on 100g of raw materials, the amount of water used is 600-800mL, preferably 600-650mL), and stirred until uniformly dispersed to obtain a coal-saving catalyst.

7. Use of the catalyst according to any one of claims 1 to 5 as a coal combustion catalyst.

8. The use according to claim 7, characterized in that: The catalyst addition amount per 100g of raw coal is 0.5-2mL of liquid coal-saving catalyst or 0.1-0.2g of solid coal-saving catalyst, preferably 0.8-1.2mL of liquid coal-saving catalyst.

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