CN114686275B - A kind of manganese oxide-zinc oxide porous desulfurizer and preparation method thereof - Google Patents

Abstract

The invention discloses a manganese oxide-zinc oxide porous desulfurizer and a preparation method thereof, belonging to the field of desulfurizer preparation. The preparation method is as follows: dissolve silicon dioxide, polyacrylonitrile and polyvinylpyrrolidone in an organic solvent to obtain a spinning solution, and obtain a PAN/PVP/ _SiO2 composite fiber membrane through electrospinning; compound PAN/PVP/ _SiO2 The fiber membrane is subjected to microwave carbonization treatment, and the obtained silica/carbon nanofibers are etched with sodium hydroxide solution to obtain porous carbon nanofibers; and zinc nitrate for hydrothermal reaction to obtain manganese oxide-zinc oxide porous desulfurizer. The desulfurizing agent of the present invention has excellent initial sulfur capacity, and still exhibits excellent desulfurizing effect after being recycled and regenerated. At the same time, the process route is simple and easy to implement, and can meet the requirements of industrial production.

Description

A kind of manganese oxide-zinc oxide porous desulfurizer and preparation method thereof

technical field

The invention relates to the field of desulfurizer preparation, in particular to a manganese oxide-zinc oxide porous desulfurizer and a preparation method thereof.

Background technique

Coal is the most abundant fossil fuel resource in the world. The clean conversion and utilization of coal is an important energy technology that meets the sustainable development goals of mankind. Gas desulfurization is the key to improving energy utilization efficiency. The existence of sulfide (H ₂ S) in the gas will not only corrode equipment and pipelines, but also cause catalyst poisoning in the subsequent treatment process. At the same time, the discharge of sulfur-containing gas into the atmosphere will cause serious environmental pollution. Therefore, efficient desulfurization is the An important prerequisite for clean and efficient conversion of coal.

At present, gas desulfurization technologies are mainly divided into two categories: dry desulfurization and wet desulfurization. Compared with wet desulfurization, dry desulfurization has the advantages of high desulfurization accuracy and easy operation, and is mainly used for fine desulfurization of gases. A large number of studies have shown that desulfurizers with zinc oxide as the active component perform better in terms of desulfurization efficiency than other metal oxide desulfurizers, because the reaction between zinc oxide and hydrogen sulfide is thermodynamically more advantageous and can be compared with H ₂ S reacts to generate metal sulfides to achieve desulfurization, which significantly reduces the content of H ₂ S in the gas.

In the process of using desulfurization agent to desulfurize the gas, the active components of metal oxides react with H ₂ S to form metal sulfides, and because the volume of sulfur atoms is larger than that of oxygen atoms, the metal sulfides occupy more than the metal oxides. Therefore, during the reaction, it is very easy to cause the internal volume expansion of the traditional desulfurizer due to the replacement of oxygen and sulfur, causing the structural collapse of the desulfurizer and the clogging of the voids, which significantly affects the desulfurization effect. Moreover, in the prior art, precipitation and kneading methods are usually used to prepare desulfurizers. The desulfurizers prepared by this process have defects such as uneven distribution of active components, small specific surface area, and underdeveloped void structure, which are difficult to meet the actual needs of efficient desulfurization.

Contents of the invention

The purpose of the present invention is to provide a manganese oxide-zinc oxide porous desulfurizer and its preparation method, so as to solve the above-mentioned problems in the prior art and ensure the efficient desulfurization effect of the desulfurizer on gas.

To achieve the above object, the present invention provides the following scheme:

The invention provides a method for preparing a manganese oxide-zinc oxide porous desulfurizer, comprising the following steps:

(1) Dissolving silicon dioxide, polyacrylonitrile and polyvinylpyrrolidone in an organic solvent to obtain a spinning solution, and then obtaining a PAN/PVP/ _SiO2 composite fiber membrane through electrospinning;

(2) The PAN/PVP/SiO _composite fiber membrane is subjected to microwave carbonization treatment to obtain silicon dioxide/carbon nanofibers, which are then etched with sodium hydroxide solution to obtain porous carbon nanofibers;

(3) Porous carbon nanofibers are activated by potassium permanganate, and then hydrothermally reacted with ammonia water, hexamethylenetetramine, and zinc nitrate to obtain the manganese oxide-zinc oxide porous desulfurizer.

Further, the mass of polyacrylonitrile, polyvinylpyrrolidone and silicon dioxide is 8:8:8-32.

Further, the microwave carbonization treatment is as follows: first, under air conditions, heat to 220-280°C at a heating rate of 5°C/min for 2 hours, and then under nitrogen conditions, heat at a heating rate of 2°C/min to 500 Insulate at -800°C for 1-2.5h.

Further, the temperature for activation of the potassium permanganate is 20-60° C., and the activation time is 30 minutes.

Further, the temperature of the hydrothermal reaction is 90° C., and the time is 24 hours.

The present invention also provides the manganese oxide-zinc oxide porous desulfurizer prepared by the above preparation method.

The invention discloses the following technical effects:

The desulfurizing agent of the present invention uses fiber materials with high flexibility and rich porosity as the carrier. The desulfurizing agent has a multi-level microscopic pore structure, which can improve the adsorption capacity and reactivity of the desulfurizing agent. The flexible feature of the fiber structure can effectively avoid desulfurization products. The structure change caused by volume increase avoids pore expansion and cracking, and the prepared desulfurizer has excellent initial sulfur capacity, and still shows excellent desulfurization effect after recycling.

Microwave has the advantages of selective heating and bulk heating, and the target product prepared by the present invention is carbon fiber and metal oxide composite material, which can absorb microwave and convert heat energy very efficiently and rapidly. The pore structure and smaller particle size make the active components of the desulfurizer highly dispersed, reflecting a higher utilization rate of the active components. At the same time, the porous structure can not only increase the loading capacity of the active components of the desulfurizer, but also enable The distribution uniformity of the active components is improved, and the porous structure can also maintain excellent diffusion and mass transfer efficiency of the desulfurizer during the reaction process, and ultimately improve the utilization rate and overall performance of the active components of the desulfurizer.

The process route for preparing the desulfurizing agent in the invention is simple and easy to implement, and can meet the requirements of industrial production.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is the SEM picture of the porous carbon nanofiber that embodiment 1 makes;

Fig. 2 is the SEM image of the manganese oxide-zinc oxide porous desulfurizer prepared in Example 1.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail. The detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features and embodiments of the present invention.

It should be understood that the terminology described in the present invention is only used to describe specific embodiments, and is not used to limit the present invention. In addition, regarding the numerical ranges in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which the documents are described. In case of conflict with any incorporated document, the contents of this specification control.

It will be apparent to those skilled in the art that various modifications and changes can be made in the specific embodiments of the present invention described herein without departing from the scope or spirit of the present invention. Other embodiments will be apparent to the skilled person from the description of the present invention. The description and examples of the invention are illustrative only.

As used herein, "comprising", "comprising", "having", "comprising" and so on are all open terms, meaning including but not limited to.

Example 1

Preparation of manganese oxide-zinc oxide porous desulfurizer:

(1) Electrospinning

Mix 0.8g of polyacrylonitrile (PAN, Mw=150,000), 0.8g of polyvinylpyrrolidone (PVP), and 2.4g of silica microspheres in 10g of N,N-dimethylformamide (DMF), and stir at room temperature for 12h , to obtain a uniform light yellow spinning solution.

Afterwards, the spinning solution was transferred to a 5mL syringe, and the spinning parameters were set as follows: spinning voltage +10kV and -2kV, spinning speed 0.10mm/min, needle 21G, and the distance between the receiver and the needle was kept at 10cm , the rotational speed of the receiver is 60r/min, the left and right moving distance of the syringe is 100mm, the moving speed is 200mm/min, the spinning temperature is set at 25°C, and the spinning time is 6h. A PAN/PVP/SiO ₂ composite fiber membrane was obtained.

(2) Microwave pre-oxidation carbonization

In a microwave tube furnace, the PAN/PVP/ _SiO2 composite fiber membrane obtained in step (1) was heated to 250 °C for 2 h at a heating rate of 5 °C/min under air conditions; then under nitrogen conditions, Heating at a heating rate of 2°C/min to 600°C for 2h to obtain silicon dioxide/carbon nanofibers SiO ₂ /CNFs.

(3) NaOH etching

Etching the silicon dioxide/carbon nanofiber SiO ₂ /CNFs in 4mol/L NaOH aqueous solution to remove SiO ₂ and obtain PCNFs porous carbon nanofibers.

(4) Potassium permanganate activation

The PCNFs porous carbon nanofibers were activated in 0.5 mol/L potassium permanganate aqueous solution at 30°C for 30 minutes to obtain MnO ₂ /PCNFs.

(5) Hydrothermal reaction

MnO ₂ /PCNFs was placed in a solution of 1mol/L ammonia, 0.03mol/L hexamethylenetetramine, and 0.03mol/L zinc nitrate for hydrothermal reaction at 90°C for 24 hours to obtain ZnO/MnO ₂ /PCNFs.

Fig. 1 is the SEM image of the porous carbon nanofibers prepared in step (3); Fig. 2 is the SEM image of the prepared manganese oxide-zinc oxide porous desulfurizer.

Example 2

Preparation of manganese oxide-zinc oxide porous desulfurizer:

(1) Electrospinning

Mix 0.8g of polyacrylonitrile (PAN, Mw=150,000), 0.8g of polyvinylpyrrolidone (PVP), and 1.6g of silica microspheres in 10g of N,N-dimethylformamide (DMF), and stir at room temperature for 12h , to obtain a uniform light yellow spinning solution.

Afterwards, the spinning solution was transferred to a 5mL syringe, and the spinning parameters were set as follows: spinning voltage +8kV and -4kV, spinning speed 0.10mm/min, 21G needle, and the distance between the receiver and the needle was kept at 10cm , the rotational speed of the receiver is 60r/min, the left and right moving distance of the syringe is 100mm, the moving speed is 200mm/min, the spinning temperature is set at 25°C, and the spinning time is 6h. A PAN/PVP/SiO ₂ composite fiber membrane was obtained.

(2) Microwave pre-oxidation carbonization

In a microwave tube furnace, the PAN/PVP/SiO ₂ composite fiber membrane obtained in step (1) was heated to 280 °C for 2 h at a heating rate of 5 °C/min under air conditions; then under nitrogen conditions, Heating at a heating rate of 2°C/min to 500°C for 1h to obtain silicon dioxide/carbon nanofibers SiO ₂ /CNFs.

(3) NaOH etching

Etching the silicon dioxide/carbon nanofiber SiO ₂ /CNFs in 4mol/L NaOH aqueous solution to remove SiO ₂ and obtain PCNFs porous carbon nanofibers.

(4) Potassium permanganate activation

The PCNFs porous carbon nanofibers were activated in 0.5 mol/L potassium permanganate aqueous solution at 20°C for 30 minutes to obtain MnO ₂ /PCNFs.

(5) Hydrothermal reaction

MnO ₂ /PCNFs was placed in a solution of 1mol/L ammonia, 0.03mol/L hexamethylenetetramine, and 0.04mol/L zinc nitrate for hydrothermal reaction at 90°C for 24 hours to obtain ZnO/MnO ₂ /PCNFs.

Example 3

Preparation of manganese oxide-zinc oxide porous desulfurizer:

(1) Electrospinning

Mix 0.8g of polyacrylonitrile (PAN, Mw=150,000), 0.8g of polyvinylpyrrolidone (PVP), and 2.4g of silica microspheres in 10g of N,N-dimethylformamide (DMF), and stir at room temperature for 12h , to obtain a uniform light yellow spinning solution.

Then the spinning solution was transferred to a 5mL syringe, and the spinning parameters were set to: spinning voltage+12kV and 0kV, spinning speed 0.10mm/min, needle 21G, the distance between the receiver and the needle was kept at 10cm, The rotating speed of the receiver is 60r/min, the left and right moving distance of the syringe is 100mm, the moving speed is 200mm/min, the spinning temperature is set at 25°C, and the spinning time is 6h. A PAN/PVP/SiO ₂ composite fiber membrane was obtained.

(2) Microwave pre-oxidation carbonization

In a microwave tube furnace, the PAN/PVP/SiO ₂ composite fiber membrane obtained in step (1) was heated to 220 °C for 2 h at a heating rate of 5 °C/min under air conditions; then under nitrogen conditions, Heating at a heating rate of 2°C/min to 800°C for 2.5h to obtain silicon dioxide/carbon nanofibers SiO ₂ /CNFs.

(3) NaOH etching

The silicon dioxide/carbon nanofiber SiO ₂ /CNFs is etched in 4mol/L NaOH aqueous solution to remove the SiO ₂ to obtain PCNFs porous carbon nanofibers.

(4) Potassium permanganate activation

The PCNFs porous carbon nanofibers were activated in 0.5 mol/L potassium permanganate aqueous solution at 60°C for 30 minutes to obtain MnO ₂ /PCNFs.

(5) Hydrothermal reaction

MnO ₂ /PCNFs was placed in a solution of 1mol/L ammonia, 0.03mol/L hexamethylenetetramine, and 0.03mol/L zinc nitrate for hydrothermal reaction at 90°C for 24 hours to obtain ZnO/MnO ₂ /PCNFs.

Example 4

Preparation of manganese oxide-zinc oxide porous desulfurizer:

(1) Electrospinning

Mix 0.8g polyacrylonitrile (PAN, Mw=150,000), 0.8g polyvinylpyrrolidone (PVP), 0.8g silica microspheres in 10g N,N-dimethylformamide (DMF), and stir at room temperature for 12h , to obtain a uniform light yellow spinning solution.

Afterwards, the spinning solution was transferred to a 5mL syringe, and the spinning parameters were set as follows: spinning voltage +10kV and -2kV, spinning speed 0.10mm/min, needle 21G, and the distance between the receiver and the needle was kept at 10cm , the rotational speed of the receiver is 60r/min, the left and right moving distance of the syringe is 100mm, the moving speed is 200mm/min, the spinning temperature is set at 25°C, and the spinning time is 6h. A PAN/PVP/SiO ₂ composite fiber membrane was obtained.

(2) Microwave pre-oxidation carbonization

In a microwave tube furnace, the PAN/PVP/ _SiO2 composite fiber membrane obtained in step (1) was heated to 250 °C for 2 h at a heating rate of 5 °C/min under air conditions; then under nitrogen conditions, Heating at a heating rate of 2°C/min to 700°C for 1.5h to obtain silicon dioxide/carbon nanofibers SiO ₂ /CNFs.

(3) NaOH etching

The silicon dioxide/carbon nanofiber SiO ₂ /CNFs is etched in 4mol/L NaOH aqueous solution to remove the SiO ₂ to obtain PCNFs porous carbon nanofibers.

(4) Potassium permanganate activation

The PCNFs porous carbon nanofibers were activated in 0.5 mol/L potassium permanganate aqueous solution at 40°C for 30 minutes to obtain MnO ₂ /PCNFs.

(5) Hydrothermal reaction

MnO ₂ /PCNFs was placed in a solution of 1mol/L ammonia, 0.03mol/L hexamethylenetetramine, and 0.02mol/L zinc nitrate for hydrothermal reaction at 90°C for 24 hours to obtain ZnO/MnO ₂ /PCNFs.

Comparative example 1

The difference from Example 1 is that the microwave pre-oxidative carbonization process is as follows:

Heat to 600°C at a heating rate of 5°C/min and keep for 4h.

Comparative example 2

The active component ZnO precursor zinc acetate powder is mixed with polyacrylonitrile PAN powder, and the mass percentage of zinc acetate in the mixture is 60%.

The mixture powder is spun by a spunbond spinning device, and the spinning process is carried out at a melt temperature of 150°C, a side blowing temperature of 15°C, and a spunbond fiber receiving distance of 5cm. A desulfurizer with zinc oxide as the active component and fiber as the carrier is prepared.

Comparative example 3

Preparation of zinc oxide desulfurizer:

Mix zinc oxide with kaolin (binder) and ammonium bicarbonate (pore-forming agent) according to the mass ratio of 90:20:10, then add an equal volume of water to form a mixture, knead and shape the mixture, and then mix it at 65 Drying at 300°C for 3 hours and roasting at 300°C for 3.5 hours to obtain a zinc oxide desulfurizer.

Perform performance verification on each desulfurizer prepared above:

Put the desulfurizer in a fixed-bed reaction device, and then feed Texaco simulated gas at a space velocity of 2000h ^-1 to conduct a desulfurization reaction at 500°C to verify the sulfur capacity of the desulfurizer after one desulfurization;

Afterwards, the desulfurization agent was regenerated using mixed air with an oxygen volume concentration of 2% at a temperature of 650°C and a space velocity of 2000 h ^-1 , and the desulfurization reaction was carried out again under the same desulfurization conditions, and the desulfurization reaction was repeated twenty times.

The sulfur capacity of the vulcanizing agent after one desulfurization, ten times of vulcanization/regeneration and twenty times of vulcanization/regeneration were counted respectively, the results are as follows:

Table 1

The above-mentioned embodiments are only to describe the preferred mode of the present invention, not to limit the scope of the present invention. Without departing from the design spirit of the present invention, those skilled in the art may make various Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (2)

1. The preparation method of the manganese oxide-zinc oxide porous desulfurizer is characterized by comprising the following steps:

(1) Dissolving silicon dioxide, polyacrylonitrile and polyvinylpyrrolidone in an organic solvent to obtain a spinning solution, and then carrying out electrostatic spinning to obtain PAN/PVP/SiO ₂ A composite fiber membrane;

(2) Mixing the PAN/PVP/SiO ₂ Carrying out microwave carbonization treatment on the composite fiber membrane to obtain silicon dioxide/carbon nanofibers, and then etching by using a sodium hydroxide solution to obtain porous carbon nanofibers;

(3) Activating porous carbon nanofibers by using potassium permanganate, and then carrying out hydrothermal reaction on the activated porous carbon nanofibers and ammonia water, hexamethylenetetramine and zinc nitrate to obtain the manganese oxide-zinc oxide porous desulfurizer;

the mass of polyacrylonitrile, polyvinylpyrrolidone and silicon dioxide is 8:8:8-32;

the microwave carbonization treatment comprises the following steps: firstly, heating to 220-280 ℃ at a heating rate of 5 ℃/min for heat preservation for 2h under the air condition, and then heating to 500-800 ℃ at a heating rate of 2 ℃/min for heat preservation for 1-2.5h under the nitrogen condition;

the temperature of the potassium permanganate during activation is 20-60 ℃, and the activation time is 30min;

the temperature of the hydrothermal reaction is 90 ℃, and the time is 24h.

2. The porous desulfurizer of manganese oxide-zinc oxide prepared by the preparation method of claim 1.

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