CN1395998A

CN1395998A - Desulfurizing binary Fe-alkali catalyst

Info

Publication number: CN1395998A
Application number: CN 02112888
Authority: CN
Inventors: 华南平; 项裕乔; 高介英; 狄俊伟; 杨平; 杜玉扣
Original assignee: Ningbo Yuandong Chemical Engineering Science And Technology Co Ltd; Taicang huanan catalyst factory; Suzhou University
Current assignee: NINGBO FAREAST CHEMICAL INDUSTRY GROUP Co Ltd
Priority date: 2002-04-15
Filing date: 2002-04-15
Publication date: 2003-02-12
Anticipated expiration: 2022-04-15
Also published as: CN1137784C

Abstract

A desulfurizing Fe-alkali composite catalyst contains hexacyanoferrate and/or hexacyanoferrite, the coordination complex chosen from citric acid, amino acid, salicylic acid, sulfosalicylic acid and tartaric acid, and polyphenolic substance chosen from hydroquinone, resorcin, catechol, etc.. Its advantages are high complex system stability, absorption speed and sulfur content, low dosage, and no environemntal pollution.

Description

Binary composite iron-alkali desulfurization catalyst

Technical Field

The invention relates to a wet oxidation type desulfurization catalyst, in particular to a composite iron-alkali desulfurization catalyst of a binary catalytic system. The desulfurization catalyst is mainly applied to the desulfurization, decarburization and decyanation of semi-water gas and shift gas in the ammonia synthesis industry; desulfurizing, decarbonizing and decyanating flue gas of city pipeline gas and other industries; desulfurization of waste gas in oil fields and oil refineries, and the like.

Background

With the rapid development of modern industry, the contents of harmful gases such as hydrogen sulfide, sulfur dioxide, hydrogen cyanide and carbon dioxide discharged into the atmosphere are increased day by day, which causes serious environmental pollution and directly harms human health. In order to protect the living environment of human beings, the development and research of desulfurization technology are increasingly urgent and important.

In the prior art, a plurality of methods for removing sulfides are available, such as activated carbon, iron oxide and the like in a dry method; the wet method is more than the improved A.D.A method, the glue copying method, the ammonia water liquid phase catalysis method,the benzoquinone method and the like. One of the desulfurization catalysts which is closer to the invention is a desulfurizer which complexes iron and EDTA, and the other is a complexing agent which complexes iron and sulfosalicylic acid. The complexing desulfurizer for iron and EDTA is prepared by adding EDTA (ethylene diamine tetraacetic acid or sodium salt thereof) complexing agent into solution, which can form a stable chelating cyclic complex with ferric iron, thereby preventing ferric iron from being formed into precipitate to cause difficulty in desulfurization. The desulfurizer has the advantages of good complexation and stability, but has the disadvantages of high price, easy degradation and serious corrosion to equipment. The iron salt and sulfosalicylic acid form a coordination complex, and the FD desulfurization catalyst takes ammonia as an absorbent. The desulfurizer has poor complexation, good overall desulfurization and regeneration performance and low price, but the complexing agent has large dosage and the stability is related to the pH value (PH value) of the solution. The above methods and desulfurization catalysts have advantages, but some of them have some disadvantages, such as small sulfur capacity and low desulfurization efficiency; some can only desulfurize and purify singly; some of them have serious corrosion to the equipment; some have difficulty in regeneration; some of the raw materials can generate new secondary pollution in the using process.

The invention aims to provide a composite iron-alkali desulfurization catalyst of a high-efficiency environment-friendly binary catalytic system with excellent comprehensive performance and strong practicability.

Disclosure of Invention

In order to achieve the purpose, the invention adopts the technical scheme that: a binary composite iron-alkali desulfurization catalyst comprises thefollowing components:

(1) a coordination complex of valence-variable metallic iron, which is hexacyanoferrate or/and hexacyanoferrate (II);

(2) the ligand can form a complex with the iron additive, and is one or a composition of more than one of citric acid, amino acid, salicylic acid, sulfosalicylic acid and tartaric acid;

(3) and polyphenols.

The relevant content and the change in the above technical scheme are explained as follows:

1. the first component is a complex of the complexed valence-variable metallic iron, and the complex is used as one of the composite iron catalysts. The second type is a ligand which forms another coordination complex with metallic iron ions in the iron additive added in the using process, the complex is another complex in the composite iron catalyst, and the coordination complex of the two types of iron forms a complex system in the desulfurization process, namely the meaning of 'complex'. The iron additive is characterized in that the iron content in the desulfurization solution is reduced due to the phenomena of running, overflowing, dripping, leaking and the like of the desulfurization solution in the desulfurization process, so that the iron additive supplements the desulfurization solution with a certain iron content. The third kind of polyphenol material is also used as one kind of catalyst to constitute binary catalyst system together with the iron in the two kinds of components.

2. The iron (III) hexacyanide salt can be: potassium, sodium and ammonium salts of iron (III) hexacyanide acid; the iron (II) hexacyanide salt can be: potassium, sodium and ammonium salts of hexacyanoferrate (II).

3. The polyphenols may be: one or more of hydroquinone, resorcinol, catechol, phloroglucinol, pyrogallol and tannin.

4. In order to prevent the catalyst from corroding equipment, the components of the technical scheme can be added with a phosphorus-containing compound.

5. The technical scheme comprises the following components in percentage by weight:

20-70% of a coordination complex of variable valence metallic iron;

10-50% of complex ligand matched with the iron additive;

10-50% of polyphenols;

1-10% of a phosphorus-containing compound.

6. When the binary composite iron-alkali desulfurization catalyst is used, an alkaline solution is used as a buffer solution of the catalyst. The alkali substance is as follows: carbonates, bicarbonates of alkali metals; carbonates, bicarbonates of ammonium; ammonia water. The catalyst does not usually comprise the alkali substances as a product, but one or more of the alkali substances are added to the catalyst and prepared into the desulfurization solution when the catalyst is used by a manufacturer. The pH value of the desulfurization solution is required to be within 7-11.

The working principle of the invention is as follows:

first, desulfurization principle

(1) Complexing of

(2) And oxidizing the mixture

(3) And absorption of the water

(4) Regeneration of the material

Second, desulfurization cycle

Absorbing hydrogen sulfide and carbon dioxide in gas of a desulfurization system by alkali liquor, oxidizing the hydrogen sulfide into elemental sulfur by a positive ferric iron complex, then enabling the desulfurization 'rich solution' to enter a regeneration system, heating by steam (or not heating), and releasing and recovering the absorbed carbon dioxide from the solution; blowing air to obtain hydroquinone (HO-C) as oxygen carrier₆H₄-OH) is oxidized by oxygen in air to hydroquinone (O ═ C)₆H₄The hydroquinone can also directly oxidize the negative divalent sulfur in the hydrogen sulfide into elemental sulfur, and the sulfur is separated and recovered; the regenerated desulfurization lean solution is returned to the desulfurization system for recycling.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

1. the invention adopts complex of variable-valence metal iron as a main desulfurization catalyst, and the iron is the most common metal, is cheap and nontoxic, and does not pollute the environment in production and use. In addition, the iron complex does not form Fe alkaline precipitate in the alkaline environment of the desulfurizing liquid, and Fe²⁺——Fe³⁺The redox potential of the pair decreases; fe³⁺Can oxidize the sulfur with negative valence state into elemental sulfur and reduce the sulfur into Fe²⁺The oxygen in the air can convert Fe²⁺Is oxidized into Fe³⁺Thereby completing the desulfurization-regeneration cycle.

2. The invention adopts two coordination complexes of variable valence metallic iron to form a compound complexing system, and has stronger catalytic activity, wherein the first complexed hexacyanoferrate (III) -hexacyanoferrate (II) is the most stable complex of all iron complexes, so the complexing system is stable, the desulfurization efficiency is high, and the sulfur capacity is large.

3. The invention uses iron and polyphenol to form a binary catalytic system, the polyphenol is used as an oxygen carrier to generate hydroquinone with oxygen in the air in the regeneration process, and the hydroquinone can automatically absorb oxygen at a very high speed to accelerate the oxygen absorptionThe transfer rate of oxygen in the liquid phase and Fe²⁺The oxidation speed of the catalyst can obviously improve the activity of the catalyst, and then the hydroquinone can directly oxidize the hydrogen sulfide into elemental sulfur, so that the desulfurization and regeneration efficiency of the catalyst is greatly improved.

4. The catalyst of the present invention has high desulfurizing efficiency and high regenerating capacity, so that it has less desulfurizing amount compared with available other desulfurizing catalyst.

5. The catalyst of the present invention has excellent hydrogen sulfide and carbon dioxide eliminating capacity, and can eliminate organic sulfur and cyanogen from gas, so that the catalyst has powerful capacity of eliminating other harmful gas compared with available common desulfurizing catalyst.

6. After the phosphorus-containing compound is added, the corrosion speed of equipment can be delayed, the corrosion effect of the catalyst on the equipment is greatly reduced, and the service life of the equipment is prolonged.

7. The elemental sulfur foam generated by regenerating the desulfurization solution prepared by the catalyst is easy to separate, cannot block the tower, can recover sulfur and cannot cause secondary pollution to the environment.

8. The catalyst of the invention is applied to the removal of hydrogen sulfide and carbon dioxide from gas, the removal efficiency can reach 99 percent, and the normal production is ensured. The elemental sulfur generated by catalysis can be recycled, and the absorbed carbon dioxide gas is released and recycled when the catalyst is regenerated, so that various process requirements can be met, and great economic benefits are generated. Such as the application in the industrial gas of synthetic ammonia, the desulfurization of conversion gas,The decarbonization, the desorption efficiency is up to 99%, the regeneration is complete, the sulfur content after desulfurization is greatly reduced, the normal production is ensured, the ammonia yield and the methanol yield are obviously improved, compared with other desulfurization catalysts, the method is applied to semi-water gas desulfurization in a chemical fertilizer plant which produces 6 ten thousand ram the loose soil with a stone-roller after sowing synthetic ammonia per year, the desulfurization cost is greatly reduced while the desulfurization efficiency is improved, and 10-20 ten thousand yuan can be saved by calculation each year. Applied to shift gas desulfurization and decyanation to reduce the total sulfur content after desulfurization to 5mg/NM³The normal operation of the copper washing or methanation process is ensured, the operation cost is reduced, the sulfur content entering the ammonia synthesis process is greatly reduced, the long-term high-quality operation of the synthetic catalyst is ensured, the yield of the fertilizer is improved, and the income can be increased by more than 20 ten thousand yuan per year through calculation. The method is applied to the shift gas desulfurization of the urea plant, the total sulfur content after desulfurization is greatly reduced, the subsequent dry desulfurization process can be cancelled, the operation cost can be saved by more than 10 ten thousand yuan, and the recovered carbon dioxide gas has improved purity, the urea yield and quality are improved, and the benefit can be increased by 10 ten thousand yuan per year.

Detailed Description

The invention is further described below with reference to the following examples:

the first embodiment is as follows: a binary composite iron-alkali desulfurization catalyst comprises the following components in percentage by weight:

50% of potassium hexacyanoferrate (III);

30% of citric acid;

15% of hydroquinone;

5 percent of phosphorus-containing compound.

Preparing alkaline desulfurization solution from the desulfurization catalyst and sodium carbonate, wherein the total amount of iron isIs 0.5-2.0 g/l, contains polyphenol substances not less than 0.2g/l, has a pH value of 8-10, and has a hydrogen sulfide content of 0.5-2 g/NM³And the desulfurization efficiency can reach 99 percent. Iron additives may be added during the desulfurization process to supplement the iron ion content to maintain the total iron content in balance.

Example two: a binary composite iron-alkali desulfurization catalyst comprises the following components in percentage by weight:

50% of sodium hexacyanoferrate (II);

30% of amino acid;

15% of hydroquinone;

5 percent of phosphorus-containing compound.

Preparing the desulfurization catalyst and sodium carbonate into alkaline desulfurization solution, wherein the total content of iron is 0.05-0.5 g/l, the content of polyphenols is more than or equal to 0.2g/l, the pH value of the solution is 8-10, and the content of hydrogen sulfide in gas is less than or equal to 500mg/NM³The total sulfur content after the desulfurization is reduced to 5mg/NM³. Iron additives may be added during the desulfurization process to supplement the iron ion content to maintain the total iron content in balance.

Claims

1. A binary composite iron-alkali desulfurization catalyst is characterized by comprising the following components:

(3) and polyphenols.

2. The binary composite iron-base desulfurization catalyst according to claim 1, characterized in that:

the iron (III) hexacyanoferrate is: potassium, sodium and ammonium salts of iron (III) hexacyanide acid;

the hexacyanoferrate (II) acid salt is: potassium, sodium and ammonium salts of hexacyanoferrate (II).

3. The binary composite iron-base desulfurization catalyst according to claim 1, characterized in that: the polyphenols are: one or more of hydroquinone, resorcinol, catechol, phloroglucinol, pyrogallol and tannin.

4. The binary composite iron-base desulfurization catalystaccording to claim 1, characterized in that: the weight percentage of each component is as follows:

20-70% of a coordination complex of variable valence metallic iron;

10-50% of complex ligand matched with the iron additive;

10-50% of polyphenol substances.

5. The binary composite iron-base desulfurization catalyst according to claim 1, characterized in that: the component also contains a phosphorus-containing compound.

6. The binary composite iron-base desulfurization catalyst according to claim 4, characterized in that: the weight percentage of the content of the phosphorus-containing compound is 1-10%.

7. The binary composite iron-base desulfurization catalyst according to claim 1, characterized in that: the catalyst takes an alkaline solution as a buffer solution of the catalyst.

8. The binary composite iron-base desulfurization catalyst according to claim 7, characterized in that: the PH value of the desulfurization solution prepared by the catalyst is within the range of 7-11.

9. The binary composite iron-base desulfurization catalyst according to claim 7, characterized in that: the alkali substance is as follows: carbonates, bicarbonates of alkali metals; carbonates, bicarbonates of ammonium; ammonia water.