Desulfurization synergist and method for preparing the same

Abstract

The present application relates to the technical field of desulfurization synergist, in particular to a desulfurization synergist for power plants and a preparation method thereof.The present application uses zinc oxide, citric acid and beta-cyclodextrin-citric acid / zinc peroxide composite material in a compounded manner.The beta-cyclodextrin-citric acid / zinc peroxide composite material is not a simple replacement of zinc oxide, and through the triple mechanism of'slow-release active oxygen + molecular inclusion + interface complexation', a synergistic enhancement network is formed with zinc oxide / citric acid, and the optimal ratio is achieved when the amount is 10 parts, so that the desulfurization rate is increased from 88% of the traditional formula to more than 96%, and the amount window is wide, thus providing a new type of solid oxidation intensifier for wet desulfurization process, which is efficient, safe and easy to scale.

Description

Technical Field

[0001] This invention relates to the field of desulfurization enhancer technology, specifically to a desulfurization enhancer for power plants and its preparation method. Background Technology

[0002] The limestone-gypsum wet process, which currently accounts for 90% of the desulfurization market, can stably meet standards under appropriate sulfur content in the designed coal. However, in recent years, the depletion of high-quality low-sulfur coal resources and the increase in the proportion of high-sulfur coal have led to a general higher-than-design sulfur content in the coal fed into the furnace. This forces an increase in the liquid-to-gas ratio of the absorber, prolonged high-load operation of the slurry circulation pump, increased system resistance, higher power consumption, reduced desulfurization efficiency, and a risk of exceeding the hourly average SO2 concentration limit at the chimney outlet. Furthermore, some older plants have insufficient reserved tower volume and limited spray layer space, making it impossible to address coal quality deterioration through simple expansion. This forces companies to blend expensive low-sulfur coal with high-sulfur coal or install expensive wet electrostatic precipitator-desulfurization co-processing towers, resulting in a sharp increase in operating costs. Therefore, achieving deep SO2 removal under high-sulfur coal conditions with minimal modification costs and operating expenses has become a crucial aspect of the green and low-carbon transformation of the thermal power industry and an urgent need for upgrading environmental protection technologies and equipment. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a desulfurization enhancer and its preparation method.

[0004] This invention is achieved through the following technical solution: A desulfurization synergist is disclosed, comprising zinc oxide, citric acid, and a β-cyclodextrin-citric acid / zinc peroxide composite material. Further, it comprises, by weight, 10 parts zinc oxide, 2.5 parts citric acid, and 5-20 parts the β-cyclodextrin-citric acid / zinc peroxide composite material. Further, the content of the β-cyclodextrin-citric acid / zinc peroxide composite material is 10 parts. Further, the content of the β-cyclodextrin-citric acid / zinc peroxide composite material is 20 parts.

[0005] Furthermore, the preparation method of the β-cyclodextrin-citric acid / zinc peroxide composite material is as follows: Step 1: Dissolve ZnSO4·7H2O in water and adjust the pH to 8, then add H2O2 aqueous solution, and sonicate for half an hour to obtain solution A; Step 2: Dissolve citric acid, Na2HPO4 and β-cyclodextrin in water, and sonicate at 80℃ for 20 min to obtain solution B; Step 3: Mix solution A and solution B and heat in an oil bath at 70°C for 1 hour. After natural cooling, centrifuge to obtain a precipitate and then dry the precipitate to obtain the β-cyclodextrin-citric acid / zinc peroxide composite material.

[0006] Furthermore, the mass ratio of ZnSO4·7H2O to citric acid is 1.2:1.

[0007] Furthermore, in step 2, the mass ratio of citric acid, Na2HPO4, and β-cyclodextrin is 1:0.6:1.

[0008] Furthermore, the zinc oxide has a particle size of <50 nm.

[0009] The present invention also provides a method for preparing a desulfurization enhancer, characterized in that zinc oxide, citric acid and β-cyclodextrin-citric acid / zinc peroxide complex are mixed evenly at room temperature, wherein the room temperature is 25~30℃.

[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention utilizes a compound of zinc oxide, citric acid, and a β-cyclodextrin-citric acid / zinc peroxide composite material. The β-cyclodextrin-citric acid / zinc peroxide composite material does not simply replace zinc oxide; it employs a triple mechanism of "slow-release active oxygen + molecular inclusion + interfacial complexation." Zinc peroxide releases H₂O₂ in water, enhancing its oxidizing capacity and significantly promoting the conversion of ZnSO₃ to ZnSO₄, thus solving the clogging problem in desulfurization equipment. Citric acid is locked within the β-CD cavity through a host-guest inclusion interaction, resulting in a high interfacial concentration and a low bulk concentration, thus preventing citric acid loss with wastewater. The β-cyclodextrin-citric acid / zinc peroxide composite material forms a synergistic reinforcing network with zinc oxide / citric acid, achieving an optimal ratio at a dosage of 10 parts, increasing the desulfurization rate from 88% in traditional formulations to over 96%, with a wide dosage window. This provides a novel solid oxidizing agent for wet desulfurization processes that is highly efficient, safe, and easily scalable. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0012] The synthesis method of the β-cyclodextrin-citric acid / zinc peroxide composite material in this invention is as follows: Dissolve 1.2 g ZnSO4·7H2O in 20 mL of deionized water, then add 10 mL of 1M NaOH dropwise to adjust the pH to 8; next, add 2 mL of 30% H2O2 aqueous solution, and sonicate the mixture under ultrasonic conditions for half an hour to obtain solution A; wherein the 30% H2O2 aqueous solution is 30 g H2O2 dissolved in 100 mL of deionized water.

[0013] Dissolve 1g citric acid, 0.6g Na2HPO4 and 1g β-cyclodextrin in 20mL deionized water and sonicate at 80℃ for 20min to obtain solution B; Solution A and solution B were mixed and heated in an oil bath at 70°C for 1 hour, then cooled naturally and centrifuged to obtain a precipitate. The precipitate was washed three times with ethanol and then dried to obtain a β-cyclodextrin-citric acid / zinc peroxide composite material.

[0014] Example 1 A desulfurization enhancer comprises, by weight, 10 parts ZnO, 2.5 parts citric acid, and 5 parts β-cyclodextrin-citric acid / zinc peroxide complex.

[0015] The desulfurization enhancer is prepared by mixing ZnO, citric acid, and a β-cyclodextrin-citric acid / zinc peroxide complex evenly at room temperature. The room temperature is 25~30℃.

[0016] Example 2 A desulfurization enhancer comprises, by weight, 10 parts ZnO, 2.5 parts citric acid, and 10 parts β-cyclodextrin-citric acid / zinc peroxide complex.

[0017] The preparation method of the desulfurization enhancer is the same as that in Example 1.

[0018] Example 3 A desulfurization enhancer comprises, by weight, 10 parts ZnO, 2.5 parts citric acid, and 20 parts β-cyclodextrin-citric acid / zinc peroxide complex.

[0019] The preparation method of the desulfurization enhancer is the same as in Example 1.

[0020] Comparative Example 1 A desulfurization enhancer, wherein the enhancer is composed of ZnO.

[0021] Comparative Example 2 A desulfurization enhancer, comprising 10 parts ZnO and 0.5 parts citric acid by weight.

[0022] The desulfurization enhancer is prepared by mixing ZnO and citric acid evenly at room temperature. The room temperature is 25~30℃.

[0023] Comparative Example 3 A desulfurization enhancer, comprising 10 parts ZnO and 1.0 parts citric acid by weight.

[0024] The desulfurization enhancer is prepared by mixing ZnO and citric acid evenly at room temperature. The room temperature is 25~30℃.

[0025] Comparative Example 4 A desulfurization enhancer, comprising 10 parts ZnO and 2.5 parts citric acid by weight.

[0026] The desulfurization enhancer is prepared by mixing ZnO and citric acid evenly at room temperature. The room temperature is 25~30℃.

[0027] Comparative Example 5 A desulfurization enhancer, comprising 10 parts ZnO and 4.0 parts citric acid by weight.

[0028] The desulfurization enhancer is prepared by mixing ZnO and citric acid evenly at room temperature. The room temperature is 25~30℃.

[0029] Comparative Example 6 A desulfurization enhancer, comprising 10 parts ZnO and 5.0 parts citric acid by weight.

[0030] The desulfurization enhancer is prepared by mixing ZnO and citric acid evenly at room temperature. The room temperature is 25~30℃.

[0031] Comparative Example 7 A desulfurization enhancer comprising, by weight, 2.5 parts citric acid and 10 parts β-cyclodextrin-citric acid / zinc peroxide complex.

[0032] The desulfurization enhancer is prepared by mixing citric acid and a β-cyclodextrin-citric acid / zinc peroxide complex evenly at room temperature. The room temperature is 25~30℃.

[0033] Comparative Example 8 A desulfurization enhancer comprising, by weight, 10 parts ZnO and 20 parts β-cyclodextrin-citric acid / zinc peroxide complex.

[0034] The desulfurization enhancer is prepared by mixing ZnO and a β-cyclodextrin-citric acid / zinc peroxide complex evenly at room temperature. The room temperature is 25~30℃.

[0035] Test Example 1 The desulfurization enhancer and limestone slurry from Examples 1-3 and Comparative Examples 1-8 were mixed at a mass ratio of 3:100 and added to the absorption tower. After the desulfurization system ran for 60 minutes, the concentration of sulfur dioxide at the flue gas outlet was recorded. The desulfurization rate of Examples 1-3 and Comparative Examples 1-8 was calculated according to the formula: Desulfurization rate = [(Concentration of SO2 in flue gas before desulfurization - Concentration of SO2 in flue gas after desulfurization) / Concentration of SO2 in flue gas before desulfurization] × 100%. The desulfurization rate results are shown in Table 1.

[0036] Table 1

[0037] As can be clearly seen from the data in Table 1, this invention, by introducing a β-cyclodextrin-citric acid / zinc peroxide composite material, enables a "step-like" leap in the desulfurization performance of the desulfurization synergist in the same limestone slurry system, and exhibits a significant synergistic threshold effect. Comparative Example 1, using only ZnO, achieved a desulfurization rate of only 81.2%, indicating that ZnO itself has limited activity in wet desulfurization. In Comparative Examples 2-6, as the amount of citric acid gradually increased from 0.5 parts to 5.0 parts, the desulfurization rate slowly increased from 81.3% to 85.4%, an increase of only 4.1 percentage points. This indicates that relying solely on citric acid for surface acidification modification of ZnO has a weak enhancing effect on the SO2 absorption / oxidation process. Furthermore, when the amount of citric acid exceeds 2.5 parts, further increasing the amount actually causes the desulfurization rate to decline (Comparative Examples 5 and 6), indicating that excessive organic acid lowers the slurry pH, inhibits CaCO3 dissolution, and weakens the main desulfurization reaction in limestone. Comparative Example 7, which completely removed ZnO and retained only citric acid and the composite material, achieved a desulfurization rate of only 83.7%, even lower than Comparative Example 4 (ZnO + 2.5 parts citric acid, 88.3%). This demonstrates that the zinc peroxide component in the composite material provides active oxygen species and promotes the SO2→SO4 transition. 2- The key to deep oxidation: Comparative Example 8, by removing citric acid and retaining only ZnO and the composite material, achieved a desulfurization rate of 86.6%, which was higher than that of Comparative Example 1, but still much lower than that of the Example. This indicates that citric acid in the slurry can chelate trace transition metal ions, inhibit the formation of inert ZnSO3 coating, and play a "synergistic activation" role in the composite material.

[0038] When ZnO, citric acid, and the β-cyclodextrin-citric acid / zinc peroxide composite material were compounded according to the proportions of this invention, the desulfurization performance exhibited a sudden change: the desulfurization rate in Example 1 reached 92.7%, an increase of 4.4 percentage points compared to Comparative Example 4; Example 2 reached a maximum value of 96.2%, and further increasing the composite material to 20 parts resulted in a slight decrease in the desulfurization rate to 93.0%, indicating that the amount of composite material also has a "saturation point." This phenomenon can be explained as follows: the β-cyclodextrin-citric acid shell imparts a slow oxygen release characteristic to ZnO2, preventing the escape of gaseous O2 caused by the one-time decomposition of H2O2, thus maximizing the utilization rate of active oxygen; the cyclodextrin cavity can encapsulate SO2 molecules, increasing their apparent solubility in the aqueous phase, while the citrate ions and Ca... 2+ A soluble complex is formed, inhibiting the coverage of the absorption interface by the CaSO4·2H2O scale layer. When the composite material exceeds 10 parts, the solid concentration in the slurry becomes too high, and particle agglomeration leads to a decrease in the effective specific surface area. Furthermore, the H2O2 produced by the decomposition of excessive ZnO2 undergoes ineffective self-decomposition in an alkaline environment, which in turn reduces the utilization efficiency of active oxygen, thus causing the desulfurization rate to decline.

[0039] In summary, the β-cyclodextrin-citric acid / zinc peroxide composite material is not a simple replacement for ZnO. Instead, it forms a synergistic reinforcing network with ZnO / citric acid through a triple mechanism of "slow-release active oxygen + molecular inclusion + interfacial complexation". The optimal ratio is achieved at a dosage of 10 parts, which increases the desulfurization rate to over 96% and has a wide dosage window. This provides a novel solid oxidant for wet desulfurization processes that is both highly efficient, safe, and easy to scale up.

[0040] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a desulfurization synergist, characterized in that, The desulfurization enhancer is composed of zinc oxide, citric acid, and a β-cyclodextrin-citric acid / zinc peroxide composite material; The preparation method of the β-cyclodextrin-citric acid / zinc peroxide composite material is as follows: Dissolve 1.2g ZnSO4•7H2O in 20mL of deionized water, then add 10mL of 1M NaOH dropwise to adjust the pH to 8; next, add 2mL of 30% H2O2 aqueous solution, and sonicate the mixture under ultrasonic conditions for half an hour to obtain solution A; wherein the 30% H2O2 aqueous solution is 30g H2O2 dissolved in 100mL of deionized water; 1g citric acid, 0.6g Na2HPO4 and 1g β-cyclodextrin were dissolved in 20mL deionized water and sonicated at 80℃ for 20min to obtain solution B; solution A and solution B were mixed and heated in an oil bath at 70℃ for 1h, then cooled naturally and centrifuged to obtain a precipitate. The precipitate was washed three times with ethanol and then dried to obtain the β-cyclodextrin-citric acid / zinc peroxide composite material. The content of the β-cyclodextrin-citric acid / zinc peroxide composite material is 10 parts; the content of zinc oxide is 10 parts, and the content of citric acid is 2.5 parts. The zinc oxide has a particle size of <50 nm; Zinc oxide, citric acid, and β-cyclodextrin-citric acid / zinc peroxide complex were mixed evenly at room temperature, which was 25-30°C.

Images