CN117430809B - One-step synthesized complex iron desulfurizing agent and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of desulfurization, and particularly discloses a one-step synthesis complex iron desulfurizing agent, a preparation method and application thereof. The preparation method comprises the following steps: adding aspartic acid, maleic anhydride, iron powder and transition metal salt into water, uniformly mixing, heating to a preset temperature, slowly adding a mixed salt solution of ammonia water and an ammonium salt solution, heating to 120-140 ℃ after the addition, carrying out heat preservation reaction, and carrying out solid-liquid separation to obtain a reaction solution; adding corrosion inhibitor and stabilizer into the reaction liquid, heating to 50-70 ℃, introducing oxidizing gas for oxidation, concentrating and drying to obtain the complex iron desulfurizing agent. The method for synthesizing the complex iron desulfurizer by one step has the advantages of simple process, greatly simplified process flow of producing the complex iron desulfurizer, low energy consumption, high complex iron content, low impurity content, stable structure, less than 1 percent of iron ion loss after repeated use for many times, safe and reliable process and suitability for large-scale production and application.

Description

One-step synthetic complex iron desulfurizing agent and its preparation method and application

Technical Field

The invention relates to the technical field of desulfurization, and in particular to a one-step synthesized complex iron desulfurizer and a preparation method and application thereof.

Background technique

The LO-CAT desulfurization process developed by an American company uses complex iron as a desulfurizer and has been widely used in my country's desulfurization industry. The complexing agents commonly used for complex iron desulfurizers include ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, polyaspartic acid, etc. Among them, polyaspartic acid (PASP) is a water-soluble polymer with the characteristics of being phosphorus-free, non-toxic, pollution-free and completely biodegradable. It has a strong chelating ability for ions and has the dual effects of corrosion inhibition and scale inhibition. It is a relatively excellent complexing agent for complex iron. At present, polyaspartic acid desulfurizers are mostly obtained by complexing polyaspartate salts with iron ion salts or ferrous ion salts. Polyaspartic acid needs to be synthesized through polycondensation, alkaline hydrolysis, neutralization and other steps from aspartic acid, maleic anhydride and other raw materials, that is, the synthesis of polyaspartic acid desulfurizers requires multi-step reactions to synthesize polyaspartic acid, and then the next step reaction is carried out to synthesize the complex iron desulfurizer.

At present, polyaspartate complex iron is mainly obtained by two-step or multi-step reaction, first synthesizing polyaspartic acid, and then reacting with iron salt to obtain polyaspartate complex iron. The process reaction steps are cumbersome, the types of raw materials used are more, the synthesis cost is high, and the obtained complex iron desulfurizer has many impurities, low iron complexing amount, and unstable complexing effect, which limits its production and application. Therefore, it is necessary to develop a synthesis method of a complex iron desulfurizer with simple process, low cost, high iron complexing amount and low impurity content.

Summary of the invention

In view of the problems of complex process, high cost, low iron complexing amount, high impurity content, etc. in the existing process for preparing complex iron desulfurizer, the present invention provides a one-step synthetic complex iron desulfurizer and a preparation method and application thereof.

In order to solve the above technical problems, the technical solution provided by the present invention is:

A one-step method for synthesizing a complex iron desulfurizing agent comprises the following steps:

Aspartic acid, maleic anhydride, iron powder and transition metal salt are added into water, mixed evenly, heated to a preset temperature, and then slowly added with a mixed salt solution of ammonia water and ammonium salt solution. After the addition, the temperature is raised to 120°C to 140°C, and the mixture is kept warm for reaction, and solid-liquid separation is performed to obtain a reaction solution.

Adding a corrosion inhibitor and a stabilizer to the reaction solution, raising the temperature to 50-70° C., introducing an oxidizing gas for oxidation, concentrating, and drying to obtain a complex iron desulfurizer;

Wherein, the adding time of the mixed salt solution is 3h to 5h.

Compared with the prior art, the one-step synthesis method of the complex iron desulfurizer provided by the present invention adopts iron powder and ammonium chloride instead of iron salt and part of ammonia water in the prior art as reaction raw materials, and reduces the heat consumption and improves the conversion rate of aspartic acid by utilizing the reaction of ammonium salt and iron powder under specific conditions. At the same time, by controlling the addition time of ammonia water and ammonium salt solution, the occurrence of side reactions is effectively reduced, the content of impurities is reduced, and the iron complex amount is also effectively increased, which is 10% higher than the polyaspartic acid complex iron content prepared by the traditional process; in addition, by adding a corrosion inhibitor and a stabilizer, the stability of the molecular structure of the polyaspartic acid complex iron is effectively improved. The polyaspartic acid complex iron prepared by the present invention is regenerated 10 times for desulfurization cycle, and the iron ion loss rate is less than 1%, which has a high cycle service life and has broad application prospects in the field of desulfurization.

The complex iron desulfurizer prepared by the present invention uses aspartic acid, maleic anhydride, iron powder, transition metal salt, ammonia water and ammonium salt as raw materials, and obtains polyaspartic acid complex iron with low impurity content, stable complex structure and high complex iron content in one step, which effectively shortens the preparation time, greatly improves the production efficiency, and has low production cost, and can be mass-produced, thus opening up a new process for the preparation and performance optimization of the complex iron desulfurizer, and has broad application prospects.

Furthermore, the transition metal salt includes at least one of manganese chloride, chromium chloride or nickel chloride.

The addition of the preferred transition metal salt can improve the ability of polyaspartic acid to complex iron ions, thereby improving the desulfurization effect of the prepared polyaspartic acid complexed iron.

Preferably, the mass ratio of aspartic acid, maleic anhydride, iron powder, transition metal salt and water is 100:60-130:50-90:0.1-0.9:50-200.

The preferred raw material ratio is beneficial to promoting the full progress of the reaction and improving the conversion rate of aspartic acid.

Preferably, the preset temperature is 80°C to 100°C.

Adding ammonia water and ammonium salt solution at 80°C to 100°C can ensure that the raw materials are mixed more fully, and preheating the raw materials to 80°C to 100°C can reduce the occurrence of side reactions and reduce the impurity content in the polyaspartic acid complex iron.

Preferably, the insulation reaction time is 2h to 5h.

The preferred reaction time can increase the conversion rate of aspartic acid and reduce the occurrence of side reactions.

Preferably, the mass ratio of the iron powder, ammonia water and ammonium salt solution is 100:10-30:600-1000.

Specifically, the mass concentration of the ammonia water is 15% to 30%, and the ammonium salt solution is a saturated ammonium chloride solution.

The preferred amount of ammonia water and ammonium salt added can ensure that the iron powder and NH ₄ ⁺ react fully and reduce the reaction cost.

Preferably, the corrosion inhibitor includes at least one of chromate, molybdate, tungstate, vanadate, orthophosphate or borate.

The above-mentioned salts in the present invention can be sodium salts, potassium salts or ammonium salts commonly used in the art, and the use of the above-mentioned salts commonly used in the art can achieve basically equivalent technical effects.

Preferably, the stabilizer comprises one or both of sorbitol or polyethylene glycol.

Preferably, the mass ratio of the aspartic acid, the corrosion inhibitor and the stabilizer is 100:0.7-1.3:1-3.

The preferred corrosion inhibitor, stabilizer and addition amount can improve the structural stabilizer and corrosion inhibition effect of the prepared polyaspartic acid complex iron and increase the number of recycling times of the complex iron desulfurizer.

It should be noted that after the heat preservation reaction is completed, nitrogen is introduced into the reaction system for purging, and then solid-liquid separation is performed, and corrosion inhibitors and stabilizers are added.

Preferably, the oxidation time is 30 min to 40 min.

Furthermore, the oxidizing gas may be air or oxygen, and air is preferred for safety and cost considerations.

Specifically, the oxidizing gas is introduced into the system by bubbling.

The present invention also provides a complex iron desulfurizing agent, which is prepared by any one of the above-mentioned one-step synthesis methods of the complex iron desulfurizing agent.

The invention also provides application of the complex iron desulfurizing agent in desulfurization of coke oven gas.

The complex iron desulfurizer provided by the invention can also be applied to the desulfurization process of coal gas, biogas and the like produced by sewage treatment plants, oil extraction, pharmaceutical plants and the like.

The present invention also provides a method for desulfurizing coke oven gas, comprising the following steps:

Dissolving any of the above-mentioned complex iron desulfurizers in water, adjusting the pH to 8.5-9.0, to obtain a complex iron desulfurizer solution;

The complex iron desulfurizing agent solution is sprayed into the desulfurizing device from the top, and coke oven gas is introduced from the bottom of the desulfurizing device to obtain a desulfurized rich liquid;

regenerating the desulfurized rich liquid to obtain a desulfurized lean liquid;

After the desulfurized lean liquid is filtered, it is circulated into the desulfurization device to continue desulfurization.

The one-step synthesis method of the complex iron desulfurizer provided by the present invention has a simple process, greatly simplifies the process flow of producing the complex iron desulfurizer, has low energy consumption, and the prepared complex iron desulfurizer has high complex iron content, low impurity content, stable structure, and iron ion loss is less than 1% after repeated use. The process is safe and reliable, suitable for large-scale production and application, and has broad application prospects in the field of desulfurization.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is an infrared spectrum of polyiron aspartate prepared in Example 1 of the present invention;

FIG. 2 is a schematic diagram of a process flow of desulfurization of coke oven gas in an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

In order to better illustrate the present invention, further examples are given below.

The iron ion content in the polyaspartic acid complexed iron in the following examples and comparative examples was detected by the total iron content detection method in HJ/T 345-2007 "Determination of Iron in Water Quality - O-Phenanthroline Spectrophotometric Method (Trial)".

Example 1

A one-step method for synthesizing a complex iron desulfurizing agent comprises the following steps:

100 kg of aspartic acid, 63 kg of maleic anhydride, 55 kg of iron powder, 0.61 kg of chromium chloride and 180 kg of water are added to a reactor, stirred evenly, and then heated to 100° C. 15 kg of 20% ammonia water and 400 kg of saturated ammonium chloride aqueous solution are mixed evenly and then slowly added to the reactor for 5 hours. After the addition, the temperature is raised to 135° C., and the reaction is kept warm for 2 hours. Nitrogen is passed through for 10 minutes, and the mixture is filtered. 0.9 kg of sodium molybdate and 1.7 kg of polyethylene glycol are added to the obtained filtrate, and the temperature is raised to 60° C. and air is bubbled for 35 minutes. The mixture is concentrated until the liquid becomes viscous, filtered, dried, and crushed to obtain a polyaspartic acid complex iron desulfurizer.

The total impurity content of aspartic acid, maleic anhydride and maleic acid in the polyaspartic acid complex iron was detected by high performance liquid chromatography and was less than 1%. The iron ion content in the polyaspartic acid complex iron was detected by spectrophotometry and was 28.73%.

The infrared spectrum of the polyaspartic acid complexed iron prepared in this example is shown in FIG1 . After analysis, the infrared spectrum is consistent with the characteristics of polyaspartic acid.

Example 2

A one-step method for synthesizing a complex iron desulfurizing agent comprises the following steps:

100 kg of aspartic acid, 100 kg of maleic anhydride, 76 kg of iron powder, 0.74 kg of manganese chloride and 130 kg of water were added into the reactor, stirred evenly, and then heated to 80°C. 10 kg of 15% ammonia water and 650 kg of saturated ammonium chloride aqueous solution were mixed evenly and then slowly added into the reactor. The feeding time was 4 hours. After the addition, the temperature was raised to 125°C, and the reaction was kept warm for 4 hours. Nitrogen was passed through for 10 minutes, and the mixture was filtered. 0.8 kg of sodium tungstate and 2.6 kg of sorbitol were added into the obtained filtrate. The temperature was controlled at 50°C and air was bubbled for 40 minutes. The mixture was concentrated until the liquid was viscous, filtered, dried, and crushed to obtain a polyaspartic acid complex iron desulfurizer.

The total impurity content of aspartic acid, maleic anhydride and maleic acid in the polyaspartic acid complex iron was detected by high performance liquid chromatography and was less than 1%. The iron ion content in the polyaspartic acid complex iron was detected by spectrophotometry and was 27.96%.

Example 3

A one-step method for synthesizing a complex iron desulfurizing agent comprises the following steps:

100 kg of aspartic acid, 125 kg of maleic anhydride, 90 kg of iron powder, 0.1 kg of manganese chloride, 0.1 kg of nickel chloride and 200 kg of water are added to the reactor, stirred evenly, and then heated to 90°C. 9 kg of 30% ammonia water and 890 kg of saturated ammonium chloride aqueous solution are mixed evenly and then slowly added to the reactor. The feeding time is 4.5 hours. After the addition, the temperature is raised to 120°C, and the reaction is kept warm for 5 hours. Nitrogen is passed through for purging for 10 minutes, and filter press is performed. 1.1 kg of ammonium molybdate and 1.2 kg of polyethylene glycol are added to the obtained filtrate, and the temperature is controlled at 65°C and air is bubbled for 35 minutes. The feed liquid is concentrated until it becomes viscous, and filter press is performed. Drying and crushing are performed to obtain a polyaspartic acid complex iron desulfurizer.

The total impurity content of aspartic acid, maleic anhydride and maleic acid in the polyaspartic acid complex iron was detected by high performance liquid chromatography and was less than 1%. The iron ion content in the polyaspartic acid complex iron was detected by spectrophotometry and was 28.39%.

Example 4

A one-step method for synthesizing a complex iron desulfurizing agent comprises the following steps:

100 kg of aspartic acid, 110 kg of maleic anhydride, 75 kg of iron powder, 0.9 kg of chromium chloride and 60 kg of water are added into a reactor, stirred evenly, and then heated to 100° C. 20 kg of 25% ammonia water and 570 kg of saturated ammonium chloride aqueous solution are mixed evenly and then slowly added into the reactor for 3 hours. After the addition, the temperature is raised to 130° C., and the reaction is kept warm for 3 hours. Nitrogen is passed through for 10 minutes, and the mixture is filtered. 0.7 kg of sodium chromate and 2.2 kg of sorbitol are added into the obtained filtrate, and the temperature is controlled at 70° C. and air is bubbled for 30 minutes. The mixture is concentrated until the liquid becomes viscous, filtered, dried, and crushed to obtain a polyaspartic acid complex iron desulfurizer.

The total impurity content of aspartic acid, maleic anhydride and maleic acid in the polyaspartic acid complex iron was detected by high performance liquid chromatography and was less than 1%. The iron ion content in the polyaspartic acid complex iron was detected by spectrophotometry and was 28.04%.

Comparative Example 1

This comparative example provides a method for preparing a complex iron desulfurizer, which is different from Example 2 only in that no ammonium chloride aqueous solution is added, and specifically comprises the following steps:

100 kg of aspartic acid, 100 kg of maleic anhydride, 76 kg of iron powder, 0.74 kg of manganese chloride and 130 kg of water were added into the reactor, stirred evenly, and then heated to 80°C, 10 kg of 15% ammonia water was slowly added into the reactor, and the feeding time was 4 hours. After the addition, the temperature was raised to 125°C, and the reaction was kept warm for 4 hours. Nitrogen was passed through for 10 minutes, and the mixture was filtered. 0.8 kg of sodium tungstate and 2.6 kg of sorbitol were added to the obtained filtrate, and the temperature was controlled at 50°C and air was bubbled for 40 minutes. The mixture was concentrated until the liquid was viscous, filtered, dried, and crushed to obtain a polyaspartic acid complex iron desulfurizer.

The total impurity content of aspartic acid, maleic anhydride and maleic acid in the polyaspartic acid complex iron was 12.6% by high performance liquid chromatography. The iron ion content in the polyaspartic acid complex iron was 0.2% by spectrophotometry. The iron content was too low and the impurity content was too high, so it could not be used for desulfurization experiments.

Comparative Example 2

This comparative example provides a method for preparing a complex iron desulfurizer, which is different from Example 3 only in the addition time of ammonia water and ammonium chloride aqueous solution, and specifically comprises the following steps:

100 kg of aspartic acid, 125 kg of maleic anhydride, 90 kg of iron powder, 0.1 kg of manganese chloride, 0.1 kg of nickel chloride and 200 kg of water are added to the reactor, stirred evenly, and then heated to 90°C. 9 kg of 30% ammonia water and 890 kg of saturated ammonium chloride aqueous solution are mixed evenly and then slowly added to the reactor. The feeding time is 1 hour. After the addition, the temperature is raised to 120°C, and the reaction is kept warm for 5 hours. Nitrogen is passed through for 10 minutes, and the filter is pressed. 1.1 kg of ammonium molybdate and 1.2 kg of polyethylene glycol are added to the obtained filtrate. The temperature is controlled at 65°C and air is bubbled for 35 minutes. The feed liquid is concentrated until it becomes viscous, filtered, dried, and crushed to obtain a polyaspartic acid complex iron desulfurizer.

The total impurity content of aspartic acid, maleic anhydride and maleic acid in the polyaspartic acid complex iron was determined by high performance liquid chromatography and was found to be 27.1%. The iron ion content in the polyaspartic acid complex iron was determined by spectrophotometry and was found to be 14.16%. The impurity content was too high and no desulfurization experiment was performed.

Comparative Example 3

This comparative example provides a method for preparing a complex iron desulfurizer, which is different from Example 1 in that ammonium chloride is replaced by an equal amount of aluminum chloride solution, and specifically comprises the following steps:

100 kg of aspartic acid, 63 kg of maleic anhydride, 55 kg of iron powder, 0.61 kg of chromium chloride and 180 kg of water are added to a reactor, stirred evenly, and then heated to 100° C. 15 kg of 20% ammonia water and 400 kg of saturated aluminum chloride aqueous solution are mixed evenly and then slowly added to the reactor for 5 hours. After the addition, the temperature is raised to 135° C., and the reaction is kept warm for 2 hours. Nitrogen is passed through for 10 minutes, and the mixture is filtered. 0.9 kg of sodium molybdate and 1.7 kg of polyethylene glycol are added to the filtrate obtained. The temperature is controlled at 60° C. and air is bubbled for 35 minutes. The mixture is concentrated until the liquid becomes viscous, filtered, dried, and crushed to obtain a polyaspartic acid complex iron desulfurizer.

The total impurity content of aspartic acid, maleic anhydride and maleic acid in the polyaspartic acid complex iron was determined by high performance liquid chromatography and was found to be 25.80%. The iron ion content in the polyaspartic acid complex iron was determined by spectrophotometry and was found to be 0.3%.

Desulfurization performance test

The desulfurization process flow chart for testing the desulfurization effect and stability of the polyaspartic acid complex iron prepared in Examples 1-4 is shown in FIG2 .

The coke oven gas used is the coal gas produced by the conventional process of the coking plant, wherein the H ₂ S content is 5740 mg/m ³ , and the coke oven gas is drawn out from the branch pipeline of the coal gas pipeline cooled to 30-40°C.

The polyaspartic acid complex iron prepared in Examples 1-4 was added to water to prepare 60 L polyaspartic acid complex iron solutions with a total iron ion concentration of 1000 mg/L, respectively. The pH was adjusted to 8.5-9.0 with sodium carbonate and sodium bicarbonate, the drawn coke oven gas was introduced into the desulfurization tower from the bottom at a rate of 5 m ³ /h, the prepared polyaspartic acid complex iron solution was sprayed into the desulfurization tower from the top of the desulfurization tower, the feed rate was 120 L/h, the temperature of the polyaspartic acid complex iron solution was controlled to be 30-35° C. When the polyaspartic acid complex iron solution was emptied, the ventilation was stopped, the desulfurized rich liquid after desulfurization was pumped into the regeneration tower from the bottom of the tower through the rich liquid pump, and regeneration was carried out by air aeration, and the air flow rate was 1 m ³ /h, the temperature of the regeneration tower is controlled at 50-60℃ by steam, the regeneration time is 25-30min, the regenerated desulfurization lean liquid is pumped into the plate and frame filter through the lean liquid pump for filtration to obtain sulfur filter cake, and the filtrate is circulated into the desulfurization tower to continue desulfurization.

After 10 cycles of regeneration and desulfurization according to the above operation, the iron ion loss rate, sulfur capacity and desulfurization efficiency of the polyaspartic acid complex iron prepared in each example are shown in Table 1.

In the above formula: c ₀ is the initial hydrogen sulfide concentration in the coke oven gas, in μg/L; c is the hydrogen sulfide concentration in the clean gas after desulfurization, in μg/L.

Table 1

Iron ion loss rate Sulfur capacity (g/L) Desulfurization efficiency Example 1 0.53% 3.0 99.76% Example 2 0.75% 2.9 99.49% Example 3 0.71% 2.9 99.55% Example 4 0.62% 3.0 99.61%

In summary, the method for preparing polyaspartate complex iron provided by the present invention has a simple process and high production efficiency. The prepared polyaspartate complex iron has a high iron ion content and a low impurity content, which can effectively improve the desulfurization effect. The complex structure is stable and can be reused many times, which effectively reduces the desulfurization cost and has a high practical value.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A method for synthesizing a complex iron desulfurizing agent in one step, which is characterized by comprising the following steps:

Adding aspartic acid, maleic anhydride, iron powder and transition metal salt into water, uniformly mixing, heating to a preset temperature, slowly adding a mixed salt solution of ammonia water and an ammonium salt solution, heating to 120-140 ℃ after the addition, carrying out heat preservation reaction, and carrying out solid-liquid separation to obtain a reaction solution;

Adding a corrosion inhibitor and a stabilizer into the reaction liquid, heating to 50-70 ℃, introducing oxidizing gas for oxidation, concentrating and drying to obtain a complex iron desulfurizing agent;

wherein the adding time of the mixed salt solution is 3-5 h;

The mass ratio of the aspartic acid to the maleic anhydride to the iron powder to the transition metal salt to the water is 100:60-130:50-90:0.1-0.9:50-200; the mass ratio of the iron powder to the ammonia water to the ammonium salt solution is 100:10-30:600-1000, the mass concentration of the ammonia water is 15% -30%, and the ammonium salt solution is an ammonium chloride saturated solution.

2. The method of one-step synthesis of a complex iron desulphurisation agent according to claim 1, wherein the transition metal salt comprises at least one of manganese chloride, chromium chloride or nickel chloride.

3. The method for one-step synthesis of a complex iron desulfurizing agent according to claim 1, wherein the preset temperature is 80 ℃ to 100 ℃; and/or

The reaction time of the heat preservation is 2-5 h.

4. The method of one-step synthesis of a complex iron desulphurisation agent according to claim 1, wherein the corrosion inhibitor comprises at least one of chromate, molybdate, tungstate, vanadate, orthophosphate or borate; and/or

The stabilizer comprises one or two of sorbitol or polyethylene glycol.

5. The method for one-step synthesis of a complex iron desulfurizing agent according to claim 1 or 4, wherein the mass ratio of aspartic acid, corrosion inhibitor and stabilizer is 100:0.7-1.3:1-3; and/or

The oxidation time is 30-40 min.

6. A complex iron desulfurizing agent, characterized by being prepared by the method for one-step synthesis of a complex iron desulfurizing agent according to any one of claims 1 to 5.

7. The use of the complex iron desulfurizing agent of claim 6 for desulfurizing coke oven gas.

8. The desulfurization method of the coke oven gas is characterized by comprising the following steps:

Dissolving the complex iron desulfurizing agent of claim 6 in water, and adjusting the pH value to 8.5-9.0 to obtain a complex iron desulfurizing agent solution;

spraying the complex iron desulfurizing agent solution into the desulfurizing device from the top of the desulfurizing device, and simultaneously introducing coke oven gas from the bottom of the desulfurizing device to obtain a desulfurizing rich solution;

Regenerating the desulfurization rich solution to obtain desulfurization lean solution;

And filtering the desulfurization lean solution, and circularly entering a desulfurization device to continuously carry out desulfurization.