High-sulfur-capacity catalyst, preparation method and application of high-sulfur-capacity catalyst in desulfurization of coal gas

Abstract

The invention provides a high-sulfur-capacity catalyst, a preparation method and application of the high-sulfur-capacity catalyst in desulfurization of coal gas, and relates to the technical field of energy conservation and environmental protection. The method comprises the following steps: firstly, preparing a deep eutectic solvent as a complexing agent, and adding a variable-valence metal compound into the deep eutectic solvent for dissolving to form a first mixed solution; adding a surfactant into the first mixed solution to obtain a second mixed solution; and adding inorganic alkali into the second mixed solution to obtain the high-sulfur-capacity catalyst. The high-sulfur-capacity catalyst is high in sulfur capacity and low in circulation amount, investment and operation cost are saved, after the high-sulfur-capacity catalyst is applied, the desulfurization efficiency is greatly improved, the solution circulation amount can be reduced, then power consumption is reduced, and the operation cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy conservation and environmental protection, and particularly relates to a high sulfur capacity catalyst, a preparation method thereof, and an application thereof in desulfurization of coal gasification gas. Background Art

[0002] China's resource endowment of rich coal, poor oil, and little gas determines China's energy consumption structure mainly based on coal. However, in recent years, with the full implementation of coal restriction and coal ban measures, the demand for natural gas has increased sharply. Industrial gas mainly refers to a mixed gas with CO + H2 as the main combustible components, which is made from coal as raw material through gasification and purification processes, and is mainly used in industries such as glass, ceramics, metallurgy, metal rolling, and casting. The industrial gas market has a huge demand. Producing clean gas from coal as raw material to replace natural gas in the industrial gas field can effectively alleviate the tight supply situation of natural gas in China. With the rapid development of the coal gasification gas industry, studying how to remove hydrogen sulfide and other sulfur-containing compounds in the gas to ensure the safe use and environmental protection production of the gas has become the focus of attention.

[0003] Currently, there are many methods for treating hydrogen sulfide in natural gas at home and abroad, such as amine method desulfurization, physical absorption method, oxidation method, wet desulfurization, and biological desulfurization method, etc. Wet oxidation method desulfurization is currently widely used in China, and its principle is to use a catalyst to oxidize HS - to precipitate elemental sulfur. The problems existing in the domestic application of wet oxidation method desulfurization technology include tower plugging, high content of by-products salts, and difficult treatment and recycling of desulfurization waste liquid, etc. Researchers use complexing agents and ferric ions to prepare a reducing complex iron catalyst. The complex iron catalyst has high desulfurization efficiency and short regeneration time, and has currently been used as a desulfurization catalyst in various fields, but there are still problems such as serious degradation of the complexing agent, low sulfur capacity, and instability, etc., which affect its long-term use.

[0004] Chinese Patent with application number 202110919373.9, titled "Wet Phase Desulfurization Catalyst and Its Preparation Method", mixes iron, metal oxides of doped elements, chelating agents (diethylenetriaminepentaacetic acid, hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, ethylenediaminetetramethylene phosphonic acid, diethylenetriaminepentamethylene phosphonic acid), polyols, deionized water, and alkali, and then stirs and reacts at 110 - 220 °C for 6 - 8 hours to prepare the desulfurization catalyst. However, this desulfurization catalyst uses organic chelating agents, which have high costs and are toxic, and have high temperature and long time in the preparation process, which is not conducive to industrial production.

[0005] The Chinese patent with the application number 202011167751.4 and the name "A Complex Iron Desulfurization Catalyst and Its Preparation Method" has raw materials for preparation including complexing agents (N-(2-hydroxyethyl)ethylenediamine-N,N’,N’-triacetic acid, N,N-bis(hydroxymethyl)glycine or 1,3-propanediamine-N,N,N’-tetraacetic acid), iron sources, modifiers (polyethylene glycol ether or polyethylene glycol), stabilizers (sodium dodecyl sulfonate, maltose or sodium p-toluenesulfonate) and pH regulators. Although this preparation method can avoid the corrosion of harmful anionic impurities, the preparation process is relatively complex, has high requirements for complexing agents and the sulfur removal rate is not ideal.

[0006] In view of this, it is very necessary to prepare a desulfurization catalyst with simple process, environmental protection and high efficiency. Summary of the Invention

[0007] The purpose of the present invention is to solve the problems that the current desulfurization catalyst preparation process is relatively complex, has high requirements for complexing agents and the sulfur removal rate effect is not good, and to provide a high sulfur capacity catalyst, a preparation method and its application in the desulfurization of coal gas.

[0008] The present invention first provides a preparation method of a high sulfur capacity catalyst, including the following steps:

[0009] Step 1: Prepare a deep eutectic solvent as a complexing agent, and the deep eutectic solvent is a homogeneous and transparent liquid formed by heating and melting a hydrogen bond acceptor and a hydrogen bond donor;

[0010] Step 2: Add a variable valence metal compound to the deep eutectic solvent in Step 1 and dissolve it to form a first mixed solution;

[0011] Step 3: Add a surfactant to the first mixed solution in Step 2 to obtain a second mixed solution;

[0012] Step 4: Add an inorganic base to the second mixed solution obtained in Step 3 to obtain a high sulfur capacity catalyst.

[0013] Preferably, the hydrogen bond acceptor is one or both of choline chloride and betaine, and the hydrogen bond donor is selected from one or more of capric acid, maleic acid, caprylic acid and dodecanoic acid.

[0014] Preferably, the mass ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1-5):(1-5).

[0015] Preferably, the temperature of heating and melting in Step 1 is 40-100 °C, and the heating and melting time is 10-30 min.

[0016] Preferably, the variable valence metal compound is one or more of soluble compounds of iron, zirconium, molybdenum or cobalt.

[0017] Preferably, the mass ratio of the variable-valence metal compound to the deep eutectic solvent is 0.05 to 0.3:1.

[0018] Preferably, the surfactant in step three is one or more of dodecyl trimethyl ammonium bromide, decanoic acid trimethyl ammonium bromide, sodium dodecyl benzene sulfonate or sodium dodecyl sulfonate.

[0019] Preferably, the mass ratio of the surfactant to the deep eutectic solvent is 0.02 to 0.2:1.

[0020] The present invention also provides a high sulfur capacity catalyst obtained by the above preparation method.

[0021] The present invention also provides the application of the above high sulfur capacity catalyst in desulfurization of coal gasification gas.

[0022] Compared with the prior art, the present invention has the following beneficial effects

[0023] 1. The high sulfur capacity catalyst of the present invention does not use organic complexing agents, is environmentally friendly, has a simple preparation process, and is suitable for industrial production.

[0024] 2. The high sulfur capacity catalyst of the present invention has a high sulfur capacity and a low circulation volume, saving investment and operating costs. After applying the high sulfur capacity catalyst, the desulfurization efficiency is greatly improved, the solution circulation volume can be reduced, thereby reducing power consumption and saving operating costs.

[0025] 3. The high sulfur capacity catalyst of the present invention inhibits salt formation, reduces the amount of waste liquid discharged, relieves the environmental protection pressure, has strong selectivity during the desulfurization process, and does not generate by-products due to over-oxidation or other reasons.

[0026] 4. The high sulfur capacity catalyst of the present invention does not corrode, effectively controls the sulfate content, reduces the alkali consumption, has a wide operating range, and is strong in anti-oil, anti-dust and heat resistance.

[0027] 5. The high sulfur capacity catalyst of the present invention has a smaller dosage and a lower control concentration compared with other complex iron-based catalysts, and the application effect is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a graph showing the change of desulfurization efficiency of the desulfurization solution reused 8 times in Example 5 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention first provides a method for preparing a high sulfur capacity catalyst, comprising the following steps:

[0031] Step 1: Prepare a deep eutectic solvent as a complexing agent. The deep eutectic solvent is a homogeneous and transparent liquid formed by heating and melting a hydrogen bond acceptor and a hydrogen bond donor. The mass ratio of the hydrogen bond acceptor to the hydrogen bond donor is preferably (1 - 5):(1 - 5), more preferably 1:2. Among them, the hydrogen bond acceptor is preferably one or both of choline chloride and betaine, more preferably choline chloride; the hydrogen bond donor is preferably one or more of capric acid, maleic acid, octanoic acid, and dodecanoic acid, more preferably octanoic acid. The heating and melting temperature is preferably 40 - 100 °C, more preferably 80 °C; the time is preferably 10 - 30 min, more preferably 25 min.

[0032] Step 2: Add a variable valence metal compound to the deep eutectic solvent in Step 1 to dissolve and form a first mixed solution. The variable valence metal compound is preferably one or more of soluble compounds of iron, zirconium, molybdenum, or cobalt, more preferably ferric chloride, cobalt nitrate, or zirconium nitrate. The mass ratio of the variable valence metal compound to the deep eutectic solvent is preferably 0.05 - 0.3:1, more preferably 0.25:1. The dissolution method is preferably one or more of stirring, heating, and ultrasonic treatment, more preferably stirring. The heating temperature for heating and dissolving is preferably 50 °C, the heating time is preferably 10 min, the ultrasonic temperature for ultrasonic treatment of the solvent is preferably 40 °C, the ultrasonic time is preferably 15 min, and the stirring dissolution time is preferably 30 min.

[0033] Step 3: Add a surfactant to the first mixed solution in Step 2 to obtain a second mixed solution. The surfactant is preferably one or more of dodecyltrimethylammonium bromide, trimethylammonium decanoate, sodium dodecylbenzenesulfonate, or sodium dodecylsulfonate, more preferably dodecyltrimethylammonium bromide. The mass ratio of the surfactant to the deep eutectic solvent is preferably 0.02 - 0.2:1, more preferably 0.1:1.

[0034] Step 4: Add an inorganic base to the second mixed solution obtained in Step 3 to obtain a high sulfur capacity catalyst. The inorganic base is preferably one or more of sodium hydroxide, sodium carbonate, or ammonia water, more preferably sodium carbonate. The mass ratio of the inorganic base to the deep eutectic solvent is preferably 1:20.

[0035] The present invention also provides a high sulfur capacity catalyst obtained by the above preparation method.

[0036] The present invention also provides the application of the above high sulfur capacity catalyst in desulfurization of coal - made gas.

[0037] Preferably, the application method includes:

[0038] Mix the above high sulfur capacity catalyst with a sodium carbonate solution (10 - 30 g / L) to absorb the gas containing hydrogen sulfide, then introduce an oxidant into the solution containing the catalyst for oxidation, and separate the oxidized solution to obtain a desulfurization solution and elemental sulfur precipitate after separation. The dosage of the high sulfur capacity catalyst is preferably 0.1 - 5 vol.%, more preferably 1 vol.%.

[0039] According to the present invention, the oxidant is preferably one or more of air, oxygen, and ozone, more preferably air. The aeration rate of the oxidant is preferably 20 - 200 L / h, more preferably 80 L / h; the oxidation time is preferably 5 - 30 min, more preferably 20 min.

[0040] According to the present invention, the separation method is preferably one or more of filtration, suction filtration, and centrifugation, more preferably centrifugation.

[0041] According to the present invention, the desulfurization solution obtained after oxidation is used for the next desulfurization process.

[0042] According to the present invention, the catalytic oxidation desulfurization efficiency of the high sulfur capacity catalyst described in the present invention is evaluated by the iodometric method.

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying 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 without creative efforts belong to the scope of protection of the present invention.

[0044] Example 1

[0045] This example provides a preparation method of a high sulfur capacity catalyst, including the following steps:

[0046] 1) Mix choline chloride and capric acid at a mass ratio of 3:2 at 80°C for 10 min to prepare a deep eutectic solvent;

[0047] 2) Add ferric chloride and cobalt nitrate (mass ratio of 1:1) to the above deep eutectic solvent according to a mass ratio of 1:10 and heat to dissolve; the heating temperature is 50°C and the heating time is 10 min.

[0048] 3) Add trimethylammonium bromide caprate to the above mixed solution, and the mass ratio of the surfactant to the deep eutectic solvent is 0.05:1.

[0049] 4) Add sodium carbonate to the above solution and mix evenly to obtain a high sulfur capacity catalyst. The mass ratio of sodium carbonate to the deep eutectic solvent is 1:20.

[0050] Mix the above catalyst (0.2 vol.%) with sodium carbonate solution (10 - 30 g / L) to absorb the gas containing hydrogen sulfide, and then introduce oxygen (100 L / h) into the solution containing the catalyst for 20 min for oxidation. Centrifuge the oxidized solution to obtain a desulfurized solution and elemental sulfur precipitate after separation.

[0051] Example 2

[0052] This example provides a preparation method of a high sulfur capacity catalyst, which includes the following steps:

[0053] 1) Mix betaine and capric acid at a mass ratio of 1:2 at 60 °C for 15 min to prepare a eutectic solvent;

[0054] 2) Add ferric chloride, cobalt nitrate and sodium molybdate (mass ratio 2:1:1) to the above eutectic solvent at a mass ratio of 1:8 and dissolve by ultrasonic treatment; the ultrasonic temperature is 40 °C and the ultrasonic time is 15 min.

[0055] 3) Add sodium dodecylbenzenesulfonate to the above mixed solution, and the mass ratio of the surfactant to the eutectic solvent is 0.08:1.

[0056] 4) Add sodium hydroxide to the above solution and mix evenly to obtain a high sulfur capacity catalyst. The mass ratio of sodium hydroxide to the eutectic solvent is 1:20.

[0057] Mix the above catalyst (2 vol.%) with sodium carbonate solution (10 - 30 g / L) to absorb the gas containing hydrogen sulfide, and then introduce air (120 L / h) into the solution containing the catalyst for 25 min for oxidation. Filter the oxidized solution by suction to obtain a desulfurized solution and elemental sulfur precipitate after separation.

[0058] Example 3

[0059] This example provides a preparation method of a high sulfur capacity catalyst, which includes the following steps:

[0060] 1) Mix choline chloride and dodecanoic acid at a mass ratio of 1:1 at 90 °C for 10 min to prepare a eutectic solvent;

[0061] 2) Add ferric chloride to the above eutectic solvent at a mass ratio of 1:5 and dissolve by heating; the heating temperature is 50 °C and the heating time is 10 min.

[0062] 3) Add sodium dodecylbenzenesulfonate to the above mixed solution, and the mass ratio of the surfactant to the eutectic solvent is 0.06:1.

[0063] 4) Add ammonia water to the above solution and mix evenly to obtain a high sulfur capacity catalyst. The mass ratio of ammonia water to the eutectic solvent is 1:20.

[0064] Mix the above catalyst (5 vol.%) with a sodium carbonate solution (10 - 30 g / L) to absorb the gas containing hydrogen sulfide, then introduce ozone (160 L / h) into the solution containing the catalyst for 10 min for oxidation, and centrifuge the oxidized solution. After separation, a desulfurized liquid and elemental sulfur precipitate are obtained.

[0065] Example 4

[0066] This example provides a preparation method of a high sulfur capacity catalyst, which includes the following steps:

[0067] 1) Mix betaine and maleic acid at a mass ratio of 1:4 at 80 °C for 15 min to prepare a eutectic solvent;

[0068] 2) Add sodium molybdate, zirconium nitrate and cobalt nitrate (mass ratio 1:1:1) to the above eutectic solvent according to a mass ratio of 1:6 and stir to dissolve; the stirring time is 30 min.

[0069] 3) Add sodium dodecyl sulfonate to the above mixed solution, and the mass ratio of the surfactant to the eutectic solvent is 0.12:1.

[0070] 4) Add sodium hydroxide to the above solution and mix evenly to obtain a high sulfur capacity catalyst. The mass ratio of sodium hydroxide to the eutectic solvent is 1:20.

[0071] Mix the above catalyst (2.5 vol.%) with a sodium carbonate solution (10 - 30 g / L) to absorb the gas containing hydrogen sulfide, then introduce oxygen (180 L / h) into the solution containing the catalyst for 15 min for oxidation, and filter the oxidized solution. After separation, a desulfurized liquid and elemental sulfur precipitate are obtained.

[0072] Example 5

[0073] This example provides a preparation method of a high sulfur capacity catalyst, which includes the following steps:

[0074] 1) Mix choline chloride and octanoic acid at a mass ratio of 1:2 at 80 °C for 25 min to prepare a eutectic solvent;

[0075] 2) Add ferric chloride, cobalt nitrate and zirconium nitrate (mass ratio 2:1:1) to the above eutectic solvent according to a mass ratio of 1:4 and stir to dissolve; the stirring time is 30 min.

[0076] 3) Add dodecyl trimethyl ammonium bromide to the above mixed solution, and the mass ratio of the surfactant to the eutectic solvent is 0.1:1.

[0077] 4) Add sodium carbonate to the above solution and mix evenly to obtain a high sulfur capacity catalyst. The mass ratio of sodium carbonate to the eutectic solvent is 1:20.

[0078] Mix the above catalyst (1 vol.%) with sodium carbonate solution (10 - 30 g / L) to absorb the gas containing hydrogen sulfide, then introduce air (80 L / h) into the solution containing the catalyst for 20 min of oxidation, and centrifuge the oxidized solution. After separation, a desulfurized solution and elemental sulfur precipitate are obtained. As Figure 1 shown, after the catalyst is recycled 8 times, the desulfurization efficiency can still reach over 99%.

[0079] Comparative Example 1

[0080] The specific preparation method is the same as that of Example 5, except that in step (1), the complexing agent is triethanolamine.

[0081] Comparative Example 2

[0082] The specific preparation method is the same as that of Example 5, except that in step (1), the complexing agent is disodium ethylenediaminetetraacetate.

[0083] Use the desulfurization catalysts in Examples 1 - 5 and Comparative Examples 1 - 2 for desulfurization treatment of coal - made gas, and measure their desulfurization efficiencies. The results are shown in Table 1 below.

[0084] Table 1

[0085]

[0086]

[0087] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific implementation manners. Obviously, many modifications and changes can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the relevant technical fields can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing a high sulfur capacity catalyst, characterized in that: The steps include: Step 1: preparing a low eutectic solvent as a complexing agent, wherein the low eutectic solvent is a uniform transparent liquid formed by heating and melting a hydrogen bond acceptor and a hydrogen bond donor; Step 2: adding the variable valence metal compound into the low eutectic solvent of step 1 to dissolve and form a first mixed solution; Step 3: adding a surfactant to the first mixed solution of step 2 to obtain a second mixed solution; Step 4: adding an inorganic base to the second mixed solution obtained in step 3 to obtain a high sulfur capacity catalyst.

2. The method for preparing a high sulfur capacity catalyst according to claim 1, characterized in that: The hydrogen bond acceptor is one or both of choline chloride and betaine, and the hydrogen bond donor is one or more of decanoic acid, maleic acid, octanoic acid and dodecanoic acid.

3. The method for preparing a high sulfur capacity catalyst according to claim 1, characterized in that: The mass ratio of the hydrogen bond acceptor to the hydrogen bond donor is (1-5):(1-5).

4. The method for preparing a high sulfur capacity catalyst according to claim 1, characterized in that: The temperature of the heating and melting in step 1 is 40 to 100° C., and the time of the heating and melting is 10 to 30 minutes.

5. The method for preparing a high sulfur capacity catalyst according to claim 1, characterized in that: The variable valence metal compound is one or more soluble compounds of iron, zirconium, molybdenum or cobalt.

6. The method for preparing a high sulfur capacity catalyst according to claim 1, characterized in that: The mass ratio of the variable valence metal compound to the low eutectic solvent is 0.05-0.3:

1.

7. The method for preparing a high sulfur capacity catalyst according to claim 1, characterized in that: The surfactant in step three is one or more of dodecyltrimethylammonium bromide, trimethylammonium bromide decanoate, sodium dodecylbenzenesulfonate or sodium dodecylsulfonate.

8. The method for preparing a high sulfur capacity catalyst according to claim 1, characterized in that: The mass ratio of the surfactant to the low eutectic solvent is 0.02-0.2:

1.

9. The high sulfur capacity catalyst obtained by the preparation method according to claim 1.

10. Use of the high sulfur capacity catalyst according to claim 9 in desulfurization of coal-to-gas.

Images