An activated carbon-based desulfurizer and its preparation method

Abstract

The present invention relates to the technical field of blast furnace gas desulfurization, and specifically relates to an activated carbon-based desulfurizer and a preparation method thereof. The desulfurizer is obtained by this method. This method includes pickling waste activated carbon to obtain modified activated carbon, cerium salt loading, combined loading of iron salt and vanadium salt, anti-chlorine and sulfur treatment, and calcination activation to obtain the desulfurizer. The sulfur capacity of the activated carbon-based desulfurizer prepared by the present invention can be increased to 44% - 48%, and the activation energy for sulfides can also be reduced. It can catalyze organic sulfur and inorganic sulfur at 20 - 50 °C, greatly reducing energy consumption; among them, the removal rates of carbonyl sulfide and carbon disulfide are both greater than or equal to 98%, and the removal rate of H2S is greater than or equal to 99%.

Description

Technical Field

[0001] The invention relates to the technical field of blast furnace gas desulfurization, and in particular to an activated carbon-based desulfurizer and a preparation method thereof. Background Art

[0002] Blast furnace gas is a combustible gas produced as a byproduct of the steel smelting process, with a total sulfur content of 80~200mg / m 3 , of which organic sulfur (mainly carbonyl sulfide COS and carbon disulfide CS2) accounts for as high as 75%~85%, and inorganic sulfur (mainly H2S) accounts for 15%-25%. These sulfides are converted into SO2 after the combustion of blast furnace gas, which increases the burden on the flue gas desulfurization facilities of steel enterprises, makes it difficult to handle by-products, and makes it difficult to meet the ultra-low emission requirements of SO2 (the requirement is SO2 emission concentration ≤35mg / m³).

[0003] How to reduce the sulfur content in blast furnace gas is a hot topic in the industry. At present, the industry mostly uses hydrolysis process, adsorption process, activated carbon-based desulfurizer or wet oxidation method to reduce the sulfur content in blast furnace gas. Specifically, in the hydrolysis process, COS and CS2 are first hydrolyzed into H2S using a catalyst (such as Al2O3-based or Fe2O3-based catalyst), and then H2S is removed; however, the catalyst is reacted with Cl in blast furnace gas. - (Cl in blast furnace gas - The content is 10~500mg / m³) and Cl - Poisoning, showing poor chlorine resistance. In the adsorption process, porous materials (such as molecular sieves or modified activated carbon) are used to directly adsorb COS and CS2, but the sulfur capacity is low (such as 8wt%~12wt%), and the adsorption capacity for COS and CS2 is weak. In terms of activated carbon-based desulfurizers, there are generally problems such as complex preparation process, low sulfur capacity (such as the sulfur capacity of silicon-modified activated carbon is generally 8wt%~10wt%), and high temperature (such as 120°C) is required for desulfurization. In addition, silicon-modified activated carbon is not very resistant to Cl in blast furnace gas. - The tolerance is less than 200mg / m³, showing poor chlorine resistance. In the wet oxidation method, although H2S can be removed to less than 10mg / m³ and the sulfur recovery rate is >90%, the equipment occupies a large area and needs to be equipped with a sulfur recovery system, which increases the investment cost.

[0004] In addition, the chemical properties of COS in blast furnace gas are stable and require high temperature (above 200°C) or strong catalytic conditions to be converted, resulting in poor COS removal effect and high removal energy consumption.

[0005] In summary, it is necessary to provide an activated carbon-based desulfurizer and a preparation method thereof to solve the problems of poor chlorine resistance, low sulfur capacity, poor COS removal effect and high removal energy consumption existing in the prior art. Summary of the Invention

[0006] The object of the present invention is to provide an activated carbon-based desulfurizer and its preparation method. The specific technical solution is as follows:

[0007] In the first aspect, the present invention provides a preparation method of an activated carbon-based desulfurizer, including:

[0008] Step S1, pickling treatment: After mixing nitric acid and hydrogen peroxide according to a mass ratio of 3-5:1 to form a mixed solution, mix waste activated carbon with the mixed solution according to a mass ratio of 1:2-5. Subsequently, after ultrasonic treatment, rinsing treatment and the first drying treatment in sequence, modified activated carbon is obtained;

[0009] Step S2, cerium salt loading: Immerse the modified activated carbon in a cerium salt solution, and after the first soaking treatment and the second drying treatment, cerium salt-loaded modified activated carbon is obtained;

[0010] Step S3, combined loading of iron salt and vanadium salt: After mixing an iron salt solution and a vanadium salt solution according to a molar ratio of iron to vanadium of 1:0.3-0.5, add an organic acid and mix evenly to obtain a combined salt solution, and adjust its pH value to 3-4; in the combined salt solution, the mass concentration of the organic acid is 1%-2%;

[0011] Immerse the cerium salt-loaded modified activated carbon in the combined salt solution, and after the second soaking treatment and the third drying treatment in sequence, modified activated carbon with combined loading of iron salt and vanadium salt is obtained;

[0012] Step S4, anti-chlorine hydrophobic treatment: Immerse the modified activated carbon treated in step S3 in an alcohol solution containing a silane coupling agent, and after the third soaking treatment and the fourth drying treatment in sequence, anti-chlorine hydrophobic modified activated carbon is obtained;

[0013] Step S5, roasting activation: First perform the first roasting treatment on the anti-chlorine hydrophobic modified activated carbon in an inert atmosphere, then perform the second roasting treatment in an air atmosphere, and finally obtain a roasted and activated activated carbon-based desulfurizer.

[0014] Optionally, in the pickling treatment, the mass concentration of the nitric acid is 3.5%-4.5%; the mass concentration of the hydrogen peroxide is 0.8%-1.2%;

[0015] The ultrasonic frequency used in the ultrasonic treatment is 30-50 kHz, the ultrasonic power is 300-600 W, and the ultrasonic time is 1-2 h; when performing the ultrasonic treatment, control the temperature of the mixed solution to be 40-60 °C;

[0016] The rinsing treatment is to rinse the activated carbon after ultrasonic treatment with hot water until the pH value of the water flowing out after rinsing is 6 to 7; the temperature of the hot water is 60 to 80 °C;

[0017] The drying temperature used in the first drying treatment is 100 to 120 °C, and the drying time is 3 to 5 h.

[0018] Optionally, the cerium salt solution includes a Ce(NO3)3 solution; the mass concentration of the Ce(NO3)3 solution is 3.5% to 4.5%;

[0019] The soaking time used in the first soaking treatment is 3 to 5 h, and the soaking temperature is 20 to 30 °C;

[0020] The drying temperature used in the second drying treatment is 100 to 120 °C, and the drying time is 2 to 4 h.

[0021] Optionally, the iron salt solution includes an Fe(NO3)3 solution; the mass concentration of the Fe(NO3)3 solution is 18% to 22%;

[0022] The vanadium salt solution includes an NH4VO3 solution; the mass concentration of the NH4VO3 solution is 6% to 8%;

[0023] The soaking time used in the second soaking treatment is 10 to 14 h, and the soaking temperature is 20 to 30 °C;

[0024] The second soaking treatment is completed under the stirring state of the combined salt solution, and the stirring speed used is 50 rpm;

[0025] The drying temperature used in the third drying treatment is 100 to 120 °C, and the drying time is 15 to 20 h.

[0026] Optionally, the waste activated carbon is waste activated carbon that adsorbs non-polar or weakly polar pollutants; the specific surface area of the waste activated carbon is greater than or equal to 800 m 2 / g, and the ash content is less than or equal to 10%;

[0027] The organic acid includes citric acid.

[0028] Optionally, dilute nitric acid is used to adjust the pH value of the combined salt solution to 3 to 4; the mass concentration of the dilute nitric acid is 5% to 8%.

[0029] Optionally, the mass concentration of the silane coupling agent in the alcohol solution is 2% to 2.5%; the silane coupling agent includes KH-550;

[0030] The soaking time used in the third soaking treatment is 0.5 to 2 h, and the soaking temperature is 20 to 30 °C;

[0031] The drying temperature used in the fourth drying treatment is 100~120°C, and the drying time is 3~5h.

[0032] Optionally, the heating rate used in the first calcination treatment is 2~5°C / min until the target calcination temperature of 200~300°C is reached, and the holding time is controlled to be 1~3h.

[0033] Optionally, the heating rate used in the second calcination treatment is 2~5°C / min until the target calcination temperature of 300~500°C is reached, and the holding time is controlled to be 2~4h.

[0034] In a second aspect, the present invention provides an activated carbon-based desulfurizer, which is prepared by using the preparation method of the activated carbon-based desulfurizer; the sulfur capacity of the activated carbon-based desulfurizer is 44%~48%; the removal rates of carbonyl sulfide and carbon disulfide by the activated carbon-based desulfurizer are both greater than or equal to 98%, and the removal rate of H2S is greater than or equal to 99%; the tolerance of the activated carbon-based desulfurizer to Cl - is greater than or equal to 500mg / m³.

[0035] Applying the technical solution of the present invention has at least the following beneficial effects:

[0036] On the one hand, a preparation method of an activated carbon-based desulfurizer provided by the present invention can increase the sulfur capacity of the prepared activated carbon-based desulfurizer to 44%~48%, and can also reduce the activation energy of sulfides, enabling the catalytic conversion of organic sulfur (such as COS and CS2) and inorganic sulfur (such as H2S) at 20~50°C, greatly reducing energy consumption; among them, the removal rates of carbonyl sulfide and carbon disulfide are both greater than or equal to 98%, and the removal rate of H2S is greater than or equal to 99%. Specifically, the present invention uses pickling treatment to remove the ash and organic pollutants on the surface of waste activated carbon, release the blocked pores, and enable the reuse of waste activated carbon; the pickling treatment can also etch the carbon skeleton of activated carbon, expand the pore diameter, and increase the specific surface area of activated carbon, such as increasing from the specific surface area of 800m 2 / g before pickling treatment to 1000m 2Above / g provides more adsorption sites for the subsequent supported active components of cerium salt, iron salt and vanadium salt; furthermore, the pickling treatment can enhance the acidification effect of nitric acid through the strong oxidation of hydrogen peroxide, promoting the conversion of the functional groups on the surface and inner wall of the pore channels of the activated carbon into oxygen-containing functional groups (such as -COOH and -OH), thus obtaining modified activated carbon; these oxygen-containing functional groups can enhance the complexation ability with cerium salt, iron salt and vanadium salt, ensuring that the active components are stably supported on the surface and inner wall of the pore channels of the modified activated carbon. The present invention adopts step S2 and step S3 for stepwise impregnation, which can promote the gradual and uniform loading of cerium salt, iron salt and vanadium salt on the surface and inner wall of the pore channels of the modified activated carbon, forming uniformly dispersed active sites. Among them, the cerium salt is converted into CeO2 through the second calcination treatment in an air atmosphere in step S5; the iron salt and vanadium salt are converted into FeVO4 spinel through the second calcination treatment in an air atmosphere in step S5; in step S5, the first calcination treatment is carried out in an inert atmosphere, which can avoid the oxidation and decomposition of the carbon skeleton of the modified activated carbon, thereby maintaining its porous structure and mechanical strength; the present invention adopts step S4 to form a silane hydrophobic layer on the surface of the modified activated carbon, and there is a microporous structure on the silane hydrophobic layer. Sulfides (such as H2S, COS and CS2) penetrate through the silane hydrophobic layer to the modified activated carbon, and then quickly combine with the active sites to generate elemental sulfur; the elemental sulfur is combined on the surface and inner wall of the pore channels of the modified activated carbon through van der Waals forces or chemical bonds. Due to the increased specific surface area and more adsorption sites of the pickling-treated modified activated carbon, the sulfur capacity increases. Among them, the principle of the reaction to generate elemental sulfur is as follows:

[0037] In FeVO4 spinel lattice, Fe 3+ and V 5+ constitute a redox pair, reducing the activation energy of the sulfide reaction, and enabling the direct catalytic oxidation of sulfide to elemental sulfur at 20 - 50 °C: Among them, Fe 3+ is reduced by the sulfide to Fe 2+ , Fe 2+ is oxidized by V 5+ to Fe 3+ , and then continues to catalyze the oxidation of sulfide to elemental sulfur; V 5+ oxidizes Fe 2+ to Fe 3+ , and then is reduced to V 4+ ;

[0038] The present invention adopts step S5 for calcination activation, so that part of Ce 4+ in the CeO2 lattice is reduced to Ce 3+ , forming oxygen vacancies. The gaseous O2 is adsorbed through the oxygen vacancies to generate active oxygen species (such as ·O - ), which can accelerate the oxidation of sulfide to elemental sulfur; in addition, the gaseous O2 adsorbed through the oxygen vacancies can oxidize V 4+ to V5+ , promoting the cycle of Fe 3+ and V 5+ redox pairs in the FeVO4 spinel lattice, and thus being able to continuously catalyze the oxidation of sulfide to elemental sulfur.

[0039] On the other hand, a preparation method of an activated carbon-based desulfurizer provided by the present invention can improve the chlorine resistance of the prepared activated carbon-based desulfurizer, increasing the tolerance to Cl - to more than 500 mg / m³, greatly reducing the Cl - poisoning risk. Specifically, in step S4, the present invention uses anti-chlorine hydrophobic treatment to form a silane hydrophobic layer on the surface of the modified activated carbon. Cl - , as a polar ion, is difficult to penetrate the silane hydrophobic layer and is thus physically blocked. In addition, negatively charged hydroxylated silane is carried on the silane hydrophobic layer, further preventing Cl - from approaching through electrostatic repulsion. Moreover, even if there are microporous structures on the silane hydrophobic layer, Cl - that penetrates through the silane hydrophobic layer to the modified activated carbon will be combined with Ce 3+ to form CeCl3 precipitate, reducing the Cl - poisoning risk.

[0040] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0042] Figure 1 is the XRD spectrum of the activated carbon-based desulfurizer prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0044] Example 1:

[0045] A preparation method of an activated carbon-based desulfurizer includes:

[0046] Step S1: Pickling treatment. Mix nitric acid and hydrogen peroxide according to a mass ratio of 4:1 to form a mixed solution. Mix the waste activated carbon with the mixed solution according to a mass ratio of 1:4. Subsequently, after ultrasonic treatment, rinsing treatment, and the first drying treatment in sequence, modified activated carbon is obtained. Before pickling treatment, the specific surface area of the waste activated carbon is 800 m 2 / g, which is increased to more than 1000 m 2 / g after pickling treatment. The waste activated carbon is waste activated carbon that adsorbs non-polar or weakly polar pollutants (such as VOCs, H2S, etc.). Avoid using waste activated carbon that adsorbs highly polar or heavy metal pollutants (such as chlorinated organic compounds, Hg 2+ and Pb 2+ etc.) to avoid interfering with subsequent modification or desulfurization reactions. Avoid using waste activated carbon containing a large amount of sulfonic acid groups (-SO3H) or strongly acidic groups. The ash content of the waste activated carbon is less than or equal to 10%;

[0047] Step S2: Cerium salt loading. Immerse the modified activated carbon in a cerium salt solution. After the first soaking treatment and the second drying treatment, cerium salt-loaded modified activated carbon is obtained;

[0048] Step S3: Combined loading of iron salt and vanadium salt. Mix an iron salt solution and a vanadium salt solution according to a molar ratio of iron to vanadium of 1:0.4, add an organic acid, and mix well to obtain a combined salt solution, and adjust its pH value to 3.5 with dilute nitric acid. In the combined salt solution, the mass concentration of the organic acid is 1.5%. Under the weakly acidic condition with a pH value of 3.5, the carboxylic acid group -COOH of citric acid dissociates into -COO⁻, forming a stable complex with Fe 3+ and V 5+ to prevent the hydrolysis and precipitation of metal ions (such as Fe(OH)3 or V2O5·nH2O, where n represents the number of crystal waters). If the pH value is too high (such as pH > 4), then Fe 3+ and V 5+ are prone to hydrolysis to form insoluble precipitates. If the pH value is too low (such as pH < 3), the complexing ability of citric acid decreases, resulting in uneven dispersion of metal ions;

[0049] Immerse the cerium salt-loaded modified activated carbon in the combined salt solution. After the second soaking treatment and the third drying treatment in sequence, modified activated carbon with combined loading of iron salt and vanadium salt is obtained;

[0050] Step S4: Anti-chlorine and hydrophobic treatment. Immerse the modified activated carbon treated in Step S3 in an alcohol solution containing a silane coupling agent. After the third soaking treatment and the fourth drying treatment in sequence, anti-chlorine and hydrophobic modified activated carbon is obtained;

[0051] Step S5: Calcination activation. First, perform the first calcination treatment on the chlorine-resistant and hydrophobic modified activated carbon under an inert atmosphere (specifically nitrogen), then perform the second calcination treatment under an air atmosphere, and finally obtain the calcined and activated activated carbon-based desulfurizer.

[0052] In the pickling treatment, the mass concentration of the nitric acid is 4%; the mass concentration of the hydrogen peroxide is 1%;

[0053] The ultrasonic treatment uses an ultrasonic frequency of 40 kHz, an ultrasonic power of 300 W, and an ultrasonic time of 2 h to increase the pickling rate; when performing the ultrasonic treatment, control the temperature of the mixed solution at 50 °C to further increase the pickling rate;

[0054] In the rinsing treatment, rinse the activated carbon after the ultrasonic treatment with hot water until the pH value of the water flowing out after rinsing is 7; the temperature of the hot water is 80 °C;

[0055] The first drying treatment uses a drying temperature of 120 °C and a drying time of 4 h.

[0056] The cerium salt solution is a Ce(NO3)3 solution; the mass concentration of the Ce(NO3)3 solution is 4%;

[0057] The first soaking treatment uses a soaking time of 4 h and a soaking temperature of 23 °C;

[0058] The second drying treatment uses a drying temperature of 110 °C and a drying time of 2 h.

[0059] The iron salt solution is an Fe(NO3)3 solution; the mass concentration of the Fe(NO3)3 solution is 18 wt%;

[0060] The vanadium salt solution is an NH4VO3 solution; the mass concentration of the NH4VO3 solution is 6 wt%;

[0061] The second soaking treatment uses a soaking time of 12 h and a soaking temperature of 23 °C;

[0062] The second soaking treatment is completed under stirring of the combined salt solution, and the stirring speed used is 50 rpm, which is convenient for fully impregnating and loading the combined salt solution onto the surface and the inner wall surface of the pore channels of the modified activated carbon. In addition, the stirring speed should not be too fast to prevent the modified activated carbon from breaking;

[0063] The third drying treatment uses a drying temperature of 110 °C and a drying time of 16 h.

[0064] The organic acid is citric acid.

[0065] Adjust the pH value of the combined salt solution to 3.5 with dilute nitric acid; the mass concentration of the dilute nitric acid is 6.5%.

[0066] The mass concentration of the silane coupling agent in the alcohol solution is 2%; the silane coupling agent is KH-550;

[0067] The soaking time for the third soaking treatment is 0.5 h, and the soaking temperature is 23 °C;

[0068] The drying temperature for the fourth drying treatment is 120 °C, and the drying time is 4 h.

[0069] In the first roasting treatment, the heating rate is 5 °C / min until the target roasting temperature of 250 °C is reached, and the holding time is controlled to be 1 h.

[0070] In the second roasting treatment, the heating rate is 3 °C / min until the target roasting temperature of 450 °C is reached, and the holding time is controlled to be 3 h.

[0071] Example 2:

[0072] Differing from Example 1, the mass concentration of the silane coupling agent in the alcohol solution is 2.5%.

[0073] Example 3:

[0074] Differing from Example 1, the mass concentration of the Ce(NO3)3 solution is 3.5%.

[0075] Example 4:

[0076] Differing from Example 1, the mass concentration of the Ce(NO3)3 solution is 4.5%.

[0077] Example 5:

[0078] Differing from Example 1, the mass concentration of the Fe(NO3)3 solution is 22%, and the mass concentration of the NH4VO3 solution is 8%.

[0079] Comparative Example 1:

[0080] Differing from Example 1, step S2 is cancelled.

[0081] Comparative Example 2:

[0082] Differing from Example 1, the adjustment of the pH value of the combined salt solution in step S3 is cancelled.

[0083] Comparative Example 3:

[0084] Differing from Example 1, the vanadium salt solution in step S3 is cancelled.

[0085] Comparative Example 4:

[0086] Differing from Example 1, step S4 was cancelled.

[0087] Comparative Example 5:

[0088] Differing from Example 1, the second calcination treatment in step S5 was cancelled.

[0089] Comparative Example 6:

[0090] Differing from Example 1, the addition amount of hydrogen peroxide in step S1 was zero.

[0091] Samples were respectively taken from the activated carbon-based desulfurizers prepared in Examples 1 to 5 and Comparative Examples 1 to 6 for sulfur capacity tests under the condition of a Cl - mass concentration of 500 mg / m³, and removal rate tests for carbonyl sulfide COS, CS2, and H2S. The test results are shown in Table 1. The test method is as follows: The selected blast furnace gas composition is as follows: the H2S mass concentration is 50 - 200 mg / m 3 (specifically 200 mg / m 3 ), the COS mass concentration is 50 - 150 mg / m 3 (specifically 150 mg / m 3 ), the CS2 mass concentration is 10 - 50 mg / m 3 (specifically 50 mg / m 3 ), the Cl⁻ mass concentration is 500 - 650 mg / m³ (specifically 500 mg / m 3 ), at an airspeed of 1000 h -1 , and at a test temperature of 30°C, the test was carried out with reference to the ASTM D6646-22 method.

[0092] Table 1 Test results under the condition of a Cl - mass concentration of 500 mg / m³

[0093]

[0094] From the data in Table 1, it can be seen that compared with Comparative Examples 1 to 6, the sulfur capacity of the activated carbon-based desulfurizer prepared in Examples 1 to 5 of the present invention can be increased to 44% - 48%, and the removal rates of carbonyl sulfide COS and carbon disulfide CS2 are both greater than or equal to 98%.

[0095] By comparing Example 1 and Comparative Example 1, it can be seen that not using the cerium salt loading in step S2 will lead to a decrease in sulfur capacity. This is because not using the cerium salt loading will, on the one hand, cause V 4+ not to be oxidized to V 5+ , thereby causing Fe in the FeVO4 spinel lattice 3+and V 5+ The redox pair cannot be recycled, thereby reducing the generation of elemental sulfur, resulting in a decrease in sulfur capacity. On the other hand, it will also increase the risk of Cl poisoning of the modified activated carbon, thereby reducing the catalytic performance of the active components (cerium salts, iron salts, and vanadium salts), reducing the generated elemental sulfur, and leading to a decrease in sulfur capacity. -

[0096] By comparing Example 1 and Comparative Example 2, it can be seen that the pH value was not adjusted, resulting in too high a pH value of the combined salt solution, which in turn caused Fe 3+ and V 5+ to be easily hydrolyzed to form insoluble precipitates, reducing the removal rates of CS2 and COS by the activated carbon-based desulfurizer, generating less elemental sulfur, and leading to a decrease in sulfur capacity.

[0097] By comparing Example 1 and Comparative Example 3, it can be seen that without using the vanadium salt solution, the FeVO4 spinel lattice cannot be formed, that is, there is no Fe 3+ and V 5+ redox pair, resulting in a significant decrease in the removal rates of CS2 and COS by the activated carbon-based desulfurizer, a significant reduction in the generated elemental sulfur, and a significant decrease in sulfur capacity.

[0098] By comparing Example 1 and Comparative Example 4, it can be seen that without using the anti-chlorine and hydrophobic treatment, the sulfur capacity is reduced. This is because without using the anti-chlorine and hydrophobic treatment, a silane hydrophobic layer cannot be formed on the surface of the modified activated carbon, losing the physical barrier to Cl, increasing the risk of Cl poisoning of the modified activated carbon, thereby reducing the catalytic performance of the active components, reducing the generated elemental sulfur, and leading to a decrease in sulfur capacity. - - poisoning risk, thereby reducing the catalytic performance of the active components, reducing the generated elemental sulfur, and leading to a decrease in sulfur capacity.

[0099] By comparing Example 1 and Comparative Example 5, it can be seen that without using the second calcination treatment, the removal rates of CS2 and COS by the activated carbon-based desulfurizer are reduced, and the sulfur capacity is reduced. This is because without using the second calcination treatment, it is difficult to effectively form the FeVO4 spinel lattice and the CeO2 lattice, resulting in a reduction in the removal rates of CS2 and COS, a reduction in the generated elemental sulfur, and a decrease in sulfur capacity.

[0100] By comparing Example 1 and Comparative Example 6, it can be seen that without using hydrogen peroxide, using only nitric acid cannot fully oxidize and decompose the organic matter on the non-active carbon, resulting in some pores on the activated carbon possibly being blocked, thereby leading to a decrease in sulfur capacity; in addition, without using hydrogen peroxide, using only nitric acid causes fewer oxygen-containing functional groups to be generated by the conversion of the functional groups on the surface and inner wall of the pores of the activated carbon, thereby reducing the complexing ability with cerium salts, iron salts, and vanadium salts, resulting in a decrease in sulfur capacity and a reduction in the removal rates of CS2 and COS.

[0101] ​​Samples were taken from the activated carbon-based desulfurizer prepared in Example 1 (i.e., Sample 1 to Sample 4) for sulfur capacity tests at different Cl - mass concentrations, and removal rate tests for carbonyl sulfide COS, CS2, and H2S. The test results are shown in Table 2. The test method is the same as above.

[0102] Table 2 Test results under different Cl - mass concentration conditions

[0103]

[0104] From the data in Table 2, it can be seen that the activated carbon-based desulfurizer prepared in Example 1 has good chlorine resistance, and the tolerance to Cl - is increased to more than 500 mg / m³.

[0105] Samples of the activated carbon-based desulfurizer prepared in Example 1 were taken for XRD pattern tests. The test results are shown in Figure 1 . From Figure 1 , it is known that FeVO4 spinel is the core catalytic phase of the activated carbon-based desulfurizer, and its high crystallinity (see the main peak at 35.5°) ensures the efficient oxidation of sulfides at low temperatures; the CeO2 crystal structure promotes the chemical fixation of Cl - through oxygen vacancies, verifying the feasibility of the dual-mechanism anti-chlorine design (i.e., physical barrier to Cl - penetration and chemical fixation of CeCl3). In addition, the absence of impurity peaks in Figure 1 indicates that the preparation process is fully optimized, and it also indicates that the active components can form a stable crystal structure on the carrier, which also shows that the active components are evenly loaded. On the contrary, if the active components are unevenly loaded, there will be a difference in the distribution concentration of the active components, resulting in the formation of non-target crystal phases and the generation of impurity peaks.

[0106] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of an activated carbon-based desulfurizer, characterized in that, Including: Step S1, pickling treatment: After mixing nitric acid and hydrogen peroxide according to a mass ratio of 3 - 5:1 to form a mixed solution, mix the waste activated carbon with the mixed solution according to a mass ratio of 1:2 - 5. Subsequently, after ultrasonic treatment, rinsing treatment, and the first drying treatment in sequence, modified activated carbon is obtained. Step S2, cerium salt loading: Immerse the modified activated carbon in a cerium salt solution, and after the first soaking treatment and the second drying treatment, cerium salt-loaded modified activated carbon is obtained. Step S3, combined loading of iron salt and vanadium salt: After mixing an iron salt solution and a vanadium salt solution according to a molar ratio of iron to vanadium of 1:0.3 - 0.5, add an organic acid and mix evenly to obtain a combined salt solution, and adjust its pH value to 3 - 4; in the combined salt solution, the mass concentration of the organic acid is 1% - 2%. Immerse the cerium salt-loaded modified activated carbon in the combined salt solution, and after the second soaking treatment and the third drying treatment in sequence, iron salt and vanadium salt combined-loaded modified activated carbon is obtained. Step S4, anti-chlorine and hydrophobic treatment: Immerse the modified activated carbon treated in Step S3 in an alcohol solution containing a silane coupling agent, and after the third soaking treatment and the fourth drying treatment in sequence, anti-chlorine and hydrophobic modified activated carbon is obtained. Step S5, calcination activation: First perform the first calcination treatment on the anti-chlorine and hydrophobic modified activated carbon in an inert atmosphere, then perform the second calcination treatment in an air atmosphere, and finally obtain a calcination-activated activated carbon-based desulfurizer.

2. The preparation method of the activated carbon-based desulfurizer according to claim 1, characterized in that, In the pickling treatment, the mass concentration of the nitric acid is 3.5% - 4.5%; the mass concentration of the hydrogen peroxide is 0.8% - 1.2%. The ultrasonic treatment uses an ultrasonic frequency of 30 - 50 kHz, an ultrasonic power of 300 - 600 W, and an ultrasonic time of 1 - 2 h; when performing the ultrasonic treatment, control the temperature of the mixed solution to be 40 - 60 °C. The rinsing treatment uses hot water to rinse the activated carbon after the ultrasonic treatment until the pH value of the water flowing out after rinsing is 6 - 7; the temperature of the hot water is 60 - 80 °C. The first drying treatment uses a drying temperature of 100 - 120 °C and a drying time of 3 - 5 h.

3. The preparation method of the activated carbon-based desulfurizer according to claim 1, wherein The cerium salt solution includes a Ce(NO3)3 solution; the mass concentration of the Ce(NO3)3 solution is 3.5% - 4.5%. The first soaking treatment uses a soaking time of 3 - 5 h and a soaking temperature of 20 - 30 °C. The second drying treatment uses a drying temperature of 100 - 120 °C and a drying time of 2 - 4 h.

4. The preparation method of the activated carbon-based desulfurizer according to claim 1, characterized in that, The iron salt solution includes an Fe(NO3)3 solution; the mass concentration of the Fe(NO3)3 solution is 18% - 22%. The vanadium salt solution includes an NH4VO3 solution; the mass concentration of the NH4VO3 solution is 6% - 8%. The second soaking treatment uses a soaking time of 10 - 14 h and a soaking temperature of 20 - 30 °C. The second soaking treatment is completed under a stirring state of the combined salt solution, and the stirring speed used is 50 rpm. The third drying treatment uses a drying temperature of 100 - 120 °C and a drying time of 15 - 20 h.

5. The preparation method of the activated carbon-based desulfurizer according to claim 1, characterized in that, The waste activated carbon is waste activated carbon that adsorbs non-polar or weakly polar pollutants; the specific surface area of the waste activated carbon is greater than or equal to 800 m 2 / g, and the ash content is less than or equal to 10%; The organic acid includes citric acid.

6. The preparation method of the activated carbon-based desulfurizer according to claim 1, characterized in that, The pH value of the combined salt solution is adjusted to 3 - 4 with dilute nitric acid; the mass concentration of the dilute nitric acid is 5% - 8%.

7. The preparation method of the activated carbon-based desulfurizer according to claim 1, characterized in that, The mass concentration of the silane coupling agent in the alcohol solution is 2% - 2.5%; the silane coupling agent includes KH-550. The soaking time for the third soaking treatment is 0.5 - 2 h, and the soaking temperature is 20 - 30 °C. The drying temperature for the fourth drying treatment is 100 - 120 °C, and the drying time is 3 - 5 h.

8. The preparation method of the activated carbon-based desulfurizer according to claim 1, wherein In the first calcination treatment, the heating rate is 2 - 5 °C / min until the target calcination temperature of 200 - 300 °C is reached, and the holding time is controlled to be 1 - 3 h.

9. The preparation method of the activated carbon-based desulfurizer according to claim 1, wherein, In the second calcination treatment, the heating rate is 2 - 5 °C / min until the target calcination temperature of 300 - 500 °C is reached, and the holding time is controlled to be 2 - 4 h.

10. An activated carbon-based desulfurizer, characterized in that, Prepared by the preparation method of the activated carbon-based desulfurizer described in claims 1 to 9; the sulfur capacity of the activated carbon-based desulfurizer is 44% to 48%; the removal rates of carbonyl sulfide and carbon disulfide by the activated carbon-based desulfurizer are both greater than or equal to 98%, and the removal rate of H2S is greater than or equal to 99%; the tolerance of the activated carbon-based desulfurizer to Cl - is greater than or equal to 500 mg / m³.

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