Method for producing formaldehyde under catalysis of triethylene diamine modified impregnated carbon

Abstract

The invention relates to the field of organic synthesis and catalysis of carbon-based materials, in particular to a method for producing formaldehyde through catalysis of triethylene diamine modified impregnated carbon. Comprising the following steps: by taking activated carbon as a carrier, pretreating, preparing a catalytic component precursor solution according to the water capacity of the activated carbon, dipping and drying, and adsorbing a reaction source triethylene diamine generated by formaldehyde in a temperature range of 55-75 DEG C, so that coexistence of a reaction source component and a catalyst component in a pore channel of the activated carbon is realized; formaldehyde can be continuously generated under the condition of 30-90% RH relative humidity. The invention provides a new method and approach for formaldehyde generation, which can provide a new thought and a new material for formaldehyde generation and is used for industrial production.

Description

Technical Field

[0001] The invention relates to the field of organic synthesis and catalysis of carbon-based materials, and in particular to a method for catalyzing the production of formaldehyde by triethylenediamine-modified impregnated carbon. Background Art

[0002] Impregnated carbon is an activated carbon carrier with a high specific surface area and a developed pore structure. It is a modified activated carbon loaded with metal oxides, metal salts or other compounds by impregnation. It has certain characteristic functions. In the field of nuclear, biological and chemical protection or gas purification, impregnated carbon is used as a functional material for the adsorption and elimination of toxic and harmful gases.

[0003] In the field of nuclear, biological and chemical protection, in order to increase the storage validity period of impregnated carbon, polyhydroxy compounds such as organic amines and metal systems are co-loaded on the pores and surface of activated carbon by sublimation deposition or impregnation loading. Polyhydroxy compounds such as organic amines form a quaternary ammonium salt protective film on the surface of impregnated carbon, which will effectively avoid the water film effect and self-accelerated component migration caused by the contact of metal components with water vapor and carbon dioxide in the air in the later stage, and to a certain extent alleviate the problem of decreased protective efficiency or deactivation of impregnated carbon as the storage period is extended. The most commonly used organic amine component is triethylenediamine.

[0004] Triethylenediamine, which has C=C and CN bonds in its structural formula, can theoretically undergo substitution, addition and other reactions. When it coexists with the loaded components in the impregnated carbon on the surface of activated carbon, the confinement effect of the activated carbon nanopores is equivalent to a microreactor, which will reduce the reaction energy of various reactions and cause triethylenediamine to undergo a series of complex chemical reactions, resulting in the release of substances such as formaldehyde.

[0005] Based on this principle, it is possible to utilize the "confinement effect" of activated carbon pores to create an effective technical approach to produce formaldehyde under low temperature conditions using metal compounds as catalysts. Summary of the invention

[0006] The present invention overcomes the shortcomings of the prior art and provides a method for catalyzing the production of formaldehyde by triethylenediamine-modified impregnated carbon. The triethylenediamine-modified impregnated carbon catalyzes the production of formaldehyde, uses activated carbon as a carrier, and loads reaction source materials and catalyst components in the pores through technical means to achieve low-temperature production of formaldehyde.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for catalyzing the production of formaldehyde by triethylenediamine modified impregnated carbon, comprising the following steps: (1) Select a specific surface area of ​​not less than 900m 2 / g, the total pore volume is not less than 0.3cm 3 / g, a porous adsorption material with a micropore ratio of not less than 85% as a carrier; (2) Weigh distilled water 1 / 2 times the water capacity of the carrier in step (1), pour it into a beaker, heat it, add metal chloride or metal sulfate, and add the carrier pretreated in step (2) after it is fully dissolved, stir, immerse, and place in a sealed container; (3) Drying the wet material after impregnation; (4) Weigh triethylenediamine, sieve it through a standard particle size sieve, take out particles not larger than 1.0 mm, physically mix them with the sample dried in step (3), and put them into a sealed container; place it in an oven so that the triethylenediamine is sublimated and adsorbed on the surface of the carrier; (5) The sample treated in step (4) is placed at room temperature and a relative humidity of 30-90% RH to continuously generate formaldehyde.

[0008] As a further limitation of the technical solution of the present invention, the porous adsorption material in step (1) is activated carbon, molecular sieve, fiber fabric, membrane material, or metal organic framework material, preferably crushed coconut shell activated carbon.

[0009] Preferably, in step (1), the carrier needs to be placed in a high-efficiency fluidized bed dryer for drying pretreatment. The drying pretreatment conditions are: air volume 27-35 Hz, heating rate 6-8°C / min, and constant temperature treatment for 10-20 min after the temperature rises to 120-130°C to complete the pretreatment. The carrier activated carbon is pretreated in an atmosphere of flowing hot air flow before impregnation, which can remove moisture from the activated carbon pores on the one hand and improve the wettability of the activated carbon on the other hand.

[0010] As a further limitation of the technical solution of the present invention, the metal component is loaded in the activated carbon carrier skeleton as a catalyst component for generating formaldehyde, the metal chloride in step (2) is at least one of copper chloride, zinc chloride, cobalt chloride and ammonium chloride, and the addition amount is 1-50% of the weight of the carrier, and the metal sulfate is at least one of zinc sulfate, copper sulfate and ammonium sulfate, and the addition amount is 1-50% of the weight of the activated carbon, preferably 10-20%. Step (2) adopts an equal amount impregnation method, and the impregnation process needs to be continuously stirred to make the solution fully wet the activated carbon and ensure uniform impregnation. After impregnation, the material needs to be placed in a sealed container, and the temperature of the mixed solution and hot steam are used to form a micro-pressure state to promote the diffusion of the solution in the activated carbon pores.

[0011] As a further limitation of the technical solution of the present invention, when the solution temperature in step (2) rises to above 40°C, a metal chloride or metal sulfate is added, stirred until fully dissolved, and continued to heat until the solution temperature is above 75°C.

[0012] As a further limitation of the technical solution of the present invention, the drying treatment in step (3) is carried out in a high-efficiency boiling dryer, and the drying treatment conditions are: air volume 27-35 Hz, heating rate 6-8°C / min, and the temperature is raised to 140-180°C and the temperature is kept constant for 40-60 minutes.

[0013] As a further limitation of the technical solution of the present invention, the amount of triethylenediamine added in step (4) is 1-6% of the mass of the sample after drying in step (3). Triethylenediamine, as a reactant to produce formaldehyde, needs to be sieved through a standard test sieve and particles smaller than 1.0 mm are used. At the same time, in order to prevent agglomeration, the operating temperature and the temperature of the supported catalyst after drying in step (3) need to be below 30°C.

[0014] As a further limitation of the technical solution of the present invention, the treatment condition in the oven in step (4) is a constant temperature of 50-75°C for more than 8 hours, and the heat-resistant temperature of the sealed container in step (4) is not less than 80°C.

[0015] As a further limitation of the technical solution of the present invention, in step (5), a higher temperature and a higher humidity condition may be selected, which will increase the amount of formaldehyde produced.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides triethylenediamine modified impregnated carbon, a carbon-based catalyst material which utilizes the "confinement effect" of activated carbon pores to produce formaldehyde at low temperature. The present invention provides a new method and approach for producing formaldehyde, which can provide new ideas and new materials for the production of formaldehyde for industrial production. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with specific embodiments.

[0018] Example 1 500 g of activated carbon sample was selected and treated at a constant temperature of (120-130) °C for (10-20) min. 225 mL of distilled water solution was measured and heated. After the temperature rose to 40 °C, 45% zinc chloride was added. The activated carbon sample was fully dissolved and the temperature was continuously raised to 75 °C. After standing, it was dried at (140-180) °C for (40-60) min. According to 6% of the mass weight of the dried sample, triethylenediamine with a particle size of no more than 1.0 mm was weighed. After mixing evenly, it was put into a sealed container and placed in an oven at a constant temperature of (50-75) °C for more than 24 hours. The sample was then tested for formaldehyde concentration at 40 °C and 70% RH relative humidity.

[0019] Example 2

[0020] 500 g of activated carbon sample was selected and treated at a constant temperature of (120-130) °C for (10-20) min. 225 mL of distilled water solution was measured and heated. After the temperature rose to 40 °C, 45% of cupric chloride was added. The activated carbon sample was fully dissolved and the temperature was continuously raised to 75 °C. After standing, it was dried at (140-180) °C for (40-60) min. According to 6% of the mass weight of the dried sample, triethylenediamine with a particle size of no more than 1.0 mm was weighed. After mixing evenly, it was put into a sealed container and placed in an oven at a constant temperature of (50-75) °C for more than 24 hours. The sample was then tested for formaldehyde concentration at 40 °C and 70% RH relative humidity.

[0021] Example 3

[0022] 500 g of activated carbon sample was selected and treated at a constant temperature of (120-130) °C for (10-20) min. 225 mL of distilled water solution was measured and heated. After the temperature rose to 40 °C, 40% copper sulfate was added. The activated carbon sample was fully dissolved and the temperature was continuously raised to 75 °C. After standing, it was dried at (140-180) °C for (40-60) min. According to 6% of the mass weight of the dried sample, triethylenediamine with a particle size of no more than 1.0 mm was weighed. After mixing evenly, it was put into a sealed container and placed in an oven at a constant temperature of (50-75) °C for more than 24 hours. The sample was then tested for formaldehyde concentration at 40 °C and 70% RH relative humidity.

[0023] Comparative Example 1 Select 500g of activated carbon sample and treat it at a constant temperature of (120-130)℃ for (10-20)min. Measure 225mL of distilled water solution and heat it. After the temperature rises to 40℃, add 40% copper sulfate. After it is fully dissolved, continue to heat the solution to 75℃ to immerse the activated carbon sample. After standing, dry it at (140-180)℃ for (40-60)min. Then test the formaldehyde concentration of the sample at 40℃ and 70%RH relative humidity.

[0024] Comparative Example 2 500 g of activated carbon sample was selected and treated at a constant temperature of (120-130) °C for (10-20) min. Triethylenediamine with a particle size not greater than 1.0 mm was weighed according to 6% of the mass weight of the sample. After mixing evenly, it was put into a sealed container and placed in an oven at a constant temperature of (50-75) °C for more than 24 hours. The sample was then tested for formaldehyde concentration at 40 °C and 70% RH relative humidity.

[0025] Performance comparison The test method for the formaldehyde concentration is to fill the power tube with a 2cm diameter and a height of 5cm with the prepared materials at 1.5Lmin - 1 cm-2 Under the conditions of air flow, normal temperature, and (30-90)%RH relative humidity, the concentration of formaldehyde in the air passing through the power tube was tested. The results are shown in the table below:

[0026] The above results show that the present invention provides a new method and approach for producing formaldehyde, which can provide new ideas and new materials for the production of formaldehyde for industrial production.

Claims

1. A method for producing formaldehyde by catalysis of triethylenediamine modified impregnated carbon, characterized in that: The following steps are involved: (1) Select a specific surface area of ​​not less than 900m 2 / g, the total pore volume is not less than 0.3cm 3 / g, a porous adsorption material with a micropore ratio of not less than 85% as a carrier; (2) Weigh distilled water 1 / 2 times the water capacity of the carrier in step (1), pour it into a beaker, heat it, add metal chloride or metal sulfate, and add the carrier pretreated in step (2) after it is fully dissolved, stir, immerse, and place in a sealed container; (3) Drying the wet material after impregnation; (4) Weigh triethylenediamine, sieve it through a standard particle size sieve, take out particles not larger than 1.0 mm, physically mix them with the sample dried in step (3), and put them into a sealed container; place it in an oven so that the triethylenediamine is sublimated and adsorbed on the surface of the carrier; (5) The sample treated in step (4) is placed at room temperature and a relative humidity of 30-90% RH to continuously generate formaldehyde.

2. The method for producing formaldehyde by catalysis of triethylenediamine modified impregnated carbon according to claim 1, characterized in that: The porous adsorption material in step (1) is activated carbon, molecular sieve, fiber fabric, membrane material, or metal organic framework material.

3. The method for producing formaldehyde by catalysis of triethylenediamine modified impregnated carbon according to claim 1, characterized in that: In step (1), the carrier also needs to be placed in a high-efficiency boiling dryer for drying pretreatment. The drying pretreatment conditions are: air volume 27-35 Hz, heating rate 6-8 ° C / min, and constant temperature treatment for 10-20 minutes after the temperature rises to 120-130 ° C to complete the pretreatment work.

4. The method for producing formaldehyde by catalysis of triethylenediamine modified impregnated carbon according to claim 1, characterized in that: The metal chloride in step (2) is at least one of copper chloride, zinc chloride, cobalt chloride and ammonium chloride, and the addition amount is 1-50% of the weight of the carrier; the metal sulfate is at least one of zinc sulfate, copper sulfate and ammonium sulfate, and the addition amount is 1-50% of the weight of the activated carbon.

5. The method for producing formaldehyde by catalysis of triethylenediamine modified impregnated carbon according to claim 1, characterized in that: When the solution temperature in step (2) rises to above 40°C, add metal chloride or metal sulfate, stir until fully dissolved, and continue heating until the solution temperature is above 75°C.

6. The method for producing formaldehyde by catalysis of triethylenediamine modified impregnated carbon according to claim 1, characterized in that: The drying treatment in step (3) is carried out in a high-efficiency fluidized bed dryer. The drying treatment conditions are: air volume 27-35 Hz, heating rate 6-8°C / min, and constant temperature treatment for 40-60 min after the temperature is raised to 140-180°C.

7. The method for producing formaldehyde by catalysis of triethylenediamine modified impregnated carbon according to claim 1, characterized in that: The amount of triethylenediamine added in step (4) is 1-6% of the mass of the sample after drying in step (3).

8. The method for producing formaldehyde by catalysis of triethylenediamine modified impregnated carbon according to claim 1, characterized in that: The treatment condition in the oven in step (4) is a constant temperature of 50-75°C for more than 8 hours, and the heat-resistant temperature of the sealed container in step (4) is not less than 80°C.

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