Method for increasing content of formaldehyde in formaldehyde aqueous solution and formaldehyde aqueous solution
By mixing methanol steam and air in a nitrogen and catalyst environment, forming and condensing formaldehyde vapor, and then mixing it with methanol, the problem of reducing formaldehyde content in one-step oxidation method is solved, and the preparation of a high-content formaldehyde aqueous solution is achieved, which has the advantages of high safety and energy-saving and environmentally friendly.
Patent Information
- Application Number
- CN202510327502.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-06
Smart Images
Figure CN120094353A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of formaldehyde preparation, and more specifically, to a method for increasing the formaldehyde content in a formaldehyde aqueous solution and the formaldehyde aqueous solution. Background Art
[0002] Formaldehyde aqueous solution, also known as formalin, has a pungent odor and can be mixed with organic solvents such as water, ethanol, acetone, etc. in any proportion. It is widely used in many industries such as chemical industry, medicine, and wood processing.
[0003] Generally, a one-step oxidation method is used to prepare formaldehyde aqueous solution, which mainly uses methanol as raw material. Under the action of high temperature and catalyst, it is oxidized with air or oxygen to generate formaldehyde, and the generated formaldehyde gas is then absorbed by water to obtain formaldehyde aqueous solution.
[0004] In many practical production processes, a high-content formaldehyde aqueous solution is required to meet specific process requirements. However, in the one-step oxidation method, water is used to absorb formaldehyde gas, which increases the water content in the formaldehyde aqueous solution, thereby reducing the formaldehyde content. Summary of the invention
[0005] In order to increase the formaldehyde content in a formaldehyde aqueous solution, the present application provides a method for increasing the formaldehyde content in a formaldehyde aqueous solution and a formaldehyde aqueous solution.
[0006] In a first aspect, the present application provides a method for increasing the formaldehyde content in a formaldehyde aqueous solution, using the following technical solution: A method for increasing the formaldehyde content in a formaldehyde solution comprises the following steps: S1: In a nitrogen and catalyst environment, methanol vapor and air are mixed and reacted at 620-670°C to generate formaldehyde gas; The water content in the air is ≤2%; S2: Condensing the formaldehyde gas to below 50° C. using a condenser to obtain condensed formaldehyde gas, and then adding methanol to obtain a formaldehyde aqueous solution.
[0007] In the related art, the formaldehyde aqueous solution is mainly prepared by a one-step oxidation method in an oxidation furnace. In order to keep the temperature in the furnace stable, steam is also introduced during the reaction. However, this further increases the water content in the formaldehyde aqueous solution, and the formaldehyde content in the obtained formaldehyde aqueous solution is generally around 37%.
[0008] By adopting the above technical scheme, the water content in the air is controlled, nitrogen is used to replace steam to balance the pressure in the furnace, the temperature and pressure are kept stable, and a multi-stage condenser is used to cool the formaldehyde vapor, which effectively reduces the generation of water vapor in the reaction, thereby increasing the formaldehyde content and obtaining a high-content formaldehyde aqueous solution, which has the advantages of high safety and energy saving and environmental protection.
[0009] At the same time, using methanol to absorb formaldehyde vapor can regulate the formaldehyde content in the formaldehyde aqueous solution, which can not only increase the formaldehyde content, but also slow down the agglomeration of high-content formaldehyde aqueous solution, effectively improving the applicability of the formaldehyde aqueous solution.
[0010] Preferably, in step S1, the mass ratio of methanol vapor to air is 1:(0.4-0.5).
[0011] By adopting the above technical solution, methanol vapor and air are added in the above mass ratio for reaction, the reaction efficiency is high, and a high content of formaldehyde vapor is obtained, which is beneficial to improving energy utilization efficiency and reducing production costs.
[0012] Preferably, in step S1, the catalyst is silver flake.
[0013] By adopting the above technical solution, the catalytic activity of snowflake silver is relatively high. Under the reaction conditions of this application, it can promote the reaction of methanol and oxygen to generate formaldehyde, effectively improving the conversion efficiency of formaldehyde.
[0014] Preferably, in the step S2, the mass ratio of the condensed formaldehyde gas to methanol is 1:(0.2-0.3).
[0015] By adopting the above technical solution, the methanol in the above content has a good absorption effect on formaldehyde gas, and the amount of methanol added can regulate the formaldehyde content in the formaldehyde aqueous solution, which is conducive to obtaining a higher concentration of formaldehyde aqueous solution.
[0016] Preferably, in step S2, the formaldehyde gas is first condensed to below 50° C. using a condenser, and the condensed formaldehyde gas is then introduced into an absorption tower, and finally methanol is added to obtain a formaldehyde aqueous solution; The absorption tower comprises a tower body, wherein an air outlet pipe is arranged on the top of the tower body, and an air inlet pipe is arranged on the bottom of the tower body; a liquid inlet pipe is arranged on the side wall of the top of the tower body, and a liquid outlet pipe is arranged on the side wall of the bottom of the tower body; a cross-tube distributor is arranged inside the tower body, and the cross-tube distributor is connected with the liquid inlet pipe; a corrugated mesh plate is arranged inside the tower body, and the corrugated mesh plate is located at the bottom of the cross-tube distributor.
[0017] By adopting the above technical solution, methanol is injected into the tower body along the liquid inlet pipe at the top of the tower body. Under the diversion effect of the cross-tube distributor, methanol is scattered on the surface of different corrugated mesh plates, which is conducive to increasing the contact area between methanol and formaldehyde vapor, promoting uniform contact between methanol and formaldehyde vapor, thereby improving the absorption efficiency of methanol to formaldehyde vapor. At the same time, the condensed formaldehyde vapor is introduced along the air inlet pipe at the bottom of the tower body. During the rising process of the tower body, it is continuously diverted by the corrugated mesh plate and maintains a large concentration difference with the scattered methanol, which is conducive to further improving the absorption efficiency of methanol to formaldehyde vapor.
[0018] Preferably, the tower body comprises an upper tower body and a lower tower body, the cross-tube distributor is located in the upper tower body, the corrugated mesh plate is located in the upper tower body and the lower tower body, and the height ratio of the upper tower body to the lower tower body is 5:1.
[0019] By adopting the above technical solution, the height of the upper tower body is increased, so the relative pressure of the rising formaldehyde vapor can be increased, which is beneficial for methanol to absorb the formaldehyde vapor and increase the formaldehyde content in the formaldehyde aqueous solution.
[0020] In a second aspect, the present application provides a formaldehyde aqueous solution, using the following technical solution: A formaldehyde aqueous solution is prepared by the method for increasing the formaldehyde content in the formaldehyde aqueous solution.
[0021] Preferably, the formaldehyde aqueous solution is composed of a mixture of 40-60% formaldehyde, 8-12% water and 28-52% methanol, calculated by weight percentage.
[0022] By adopting the above technical scheme, the formaldehyde aqueous solution prepared by the method of the present application has a formaldehyde content of up to 40-60%. Compared with the formaldehyde aqueous solution with a formaldehyde content of 37% prepared by a one-step oxidation method, it has a higher formaldehyde content, can meet the requirements of specific processes, and has a wider applicability.
[0023] In summary, this application has the following beneficial effects: 1. The preparation method of the present application effectively reduces the addition of water during the reaction process by controlling the moisture content in the air, replacing steam with nitrogen to maintain the reaction temperature and pressure, and cooling the formaldehyde vapor with a multi-stage condenser; then, methanol is used to absorb the formaldehyde vapor to obtain a formaldehyde aqueous solution with a formaldehyde content of up to 40-60%; therefore, compared with the formaldehyde aqueous solution with a formaldehyde content of 37% prepared in the related art, the present application increases the formaldehyde content in the formaldehyde aqueous solution, can meet the requirements of a specific process, and has a wide range of applicability; 2. The absorption tower of the present application introduces condensed formaldehyde vapor along the bottom of the tower and methanol along the top of the tower, and the methanol can be evenly scattered on the surface of the corrugated mesh tube through a cross-tube distributor, thereby increasing the contact area between methanol and formaldehyde vapor in the tower, and maintaining a large concentration difference between methanol and formaldehyde vapor in the tower, thereby effectively improving the absorption efficiency of methanol to formaldehyde vapor. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a schematic diagram of the overall structure of the absorption tower in Example 1 of the present application; Figure 2 is a schematic cross-sectional structure diagram of the absorption tower in Example 1 of the present application; Figure 3 is a schematic diagram of the overall structure of the cross-tube distributor in Example 1 of the present application; Figure 4 It is a schematic diagram of the overall structure of the corrugated mesh plate and the fixing frame in Example 1 of the present application.
[0025] Figure numerals: 1, tower body; 101, upper tower body; 102, lower tower body; 2, air outlet pipe; 3, air inlet pipe; 4, liquid inlet pipe; 5, liquid outlet pipe; 6, cross-tube distributor; 7, corrugated mesh plate; 8, fixing frame. DETAILED DESCRIPTION
[0026] The present application is further described in detail below with reference to the accompanying drawings and embodiments.
[0027] Performance Testing With reference to GB / T 685-2013 standard, the formaldehyde content of the formaldehyde aqueous solutions prepared in the examples and comparative examples of the present application was tested. Example Example
[0028] An absorption tower, referring to Figure 1 , comprising a tower body 1, an air outlet pipe 2 is arranged at the top of the tower body 1, an air inlet pipe 3 is arranged at the bottom of the tower body 1; a liquid inlet pipe 4 is arranged at the top side wall of the tower body 1, and a liquid outlet pipe 5 is arranged at the bottom side wall of the tower body 1. Condensed formaldehyde gas is introduced into the tower body 1 along the air inlet pipe 3, and methanol is introduced into the tower body 1 along the liquid inlet pipe 4. After the rising formaldehyde gas contacts the descending methanol, the formaldehyde aqueous solution obtained by the methanol absorbing the formaldehyde gas can be discharged along the liquid outlet pipe 5, and the residual formaldehyde gas flows back to the air inlet pipe 3 along the air outlet pipe 2 to be absorbed again.
[0029] Reference Figure 2 The tower body 1 is composed of three layers of upper tower body 101 and two layers of lower tower body 102. The total height ratio of the upper tower body 101 and the lower tower body 102 is 5:1, which can effectively increase the relative pressure of the rising formaldehyde gas. Figure 2 and Figure 3 A cross-tube distributor 6 is fixedly arranged inside the upper tower body 101, and the cross-tube distributor 6 is connected to the liquid inlet pipe 4. Figure 2 and Figure 4 The upper tower body 101 and the lower tower body 102 are provided with multiple layers of corrugated mesh plates 7 made of stainless steel, and each layer of corrugated mesh plates 7 is arranged in parallel and welded to the upper tower body 101 and the lower tower body 102 through an annular fixing plate. The nozzle on the surface of the cross-tube distributor 6 evenly sprays the formaldehyde in the liquid inlet pipe 4 on the surface of the multiple layers of corrugated mesh plates 7, effectively increasing the contact area between methanol and formaldehyde vapor, which is beneficial to improving the absorption efficiency of methanol to formaldehyde vapor.
[0030] Reference Figure 4In order to improve the stability of the corrugated mesh plate 7 in the upper tower body 101 and the lower tower body 102, a cross-shaped fixing frame 8 is fixedly provided on the inner walls of the upper tower body 101 and the lower tower body 102. The fixing frame 8 is located at the bottom of the corrugated mesh plate 7 and is fixedly connected to the corrugated mesh plate 7, which can effectively slow down the collapse of the corrugated mesh plate 7.
[0031] The implementation principle of Example 1 is as follows: formaldehyde gas is introduced into the tower body 1 from the air inlet pipe 3 of the lower tower body 102, and methanol is introduced into the tower body 1 from the liquid inlet pipe 4 of the upper tower body 101. Due to the height setting of the upper tower body 101 and the lower tower body 102, the relative pressure of the formaldehyde gas is increased, which is conducive to promoting the contact between the formaldehyde gas and the methanol. At the same time, the cross-tube distributor 6 can spray the methanol in the liquid inlet pipe 4 onto the surface of the multi-layer corrugated mesh plate 7, effectively increasing the contact area between the methanol and the formaldehyde gas, thereby improving the absorption efficiency of the methanol to the formaldehyde gas. Example
[0032] An absorption tower, which is different from Example 1 in that the total height ratio of the upper tower body 101 and the lower tower body 102 is 1:1. Example
[0033] An absorption tower, which is different from Example 1 in that the total height ratio of the upper tower body 101 and the lower tower body 102 is 1:5. Example
[0034] A method for increasing the formaldehyde content in a formaldehyde solution comprises the following steps: S1: nitrogen, 1000kg methanol vapor and 450kg air are introduced into an oxidation furnace containing silver flakes, and then mixed and reacted in the oxidation furnace at a temperature of 650°C and a pressure of 0.02kg to generate formaldehyde gas; S2: Condensing the formaldehyde gas to below 50°C using a multi-stage condenser to obtain condensed formaldehyde gas. First, 1000 kg of condensed formaldehyde gas is introduced into an absorption tower, and then 250 kg of methanol is introduced into the absorption tower. The methanol contacts and absorbs the formaldehyde gas to obtain a formaldehyde aqueous solution.
[0035] In the present application example, the absorption tower adopts the absorption tower prepared in Example 1, and the specific steps include: The condensed formaldehyde gas is introduced into the tower body 1 along the air inlet pipe 3, and the methanol is introduced into the tower body 1 along the liquid inlet pipe 4. The cross-tube distributor 6 sprays the methanol in the liquid inlet pipe 4 onto the surface of the multi-layer corrugated mesh plate 7, where it contacts and absorbs the rising formaldehyde gas. The generated formaldehyde aqueous solution can be discharged along the liquid outlet pipe 5, and the residual formaldehyde gas can flow back to the air inlet pipe 3 along the air outlet pipe 2 to be absorbed again.
[0036] In the embodiment of the present application, the water content in the air is ≤2%, and the model of the oxidation furnace is ILE, which is purchased from Wuxi Leite Petrochemical Heavy Industry Equipment Co., Ltd. Example
[0037] A method for increasing the formaldehyde content in a formaldehyde aqueous solution, which is different from Example 1 in that, in step S1, nitrogen, 1000 kg of methanol vapor and 400 kg of air are introduced into an oxidation furnace containing silver flakes, and then mixed and reacted in the oxidation furnace at a temperature of 620°C and a pressure of 0.015 kg to generate formaldehyde gas. Example
[0038] A method for increasing the formaldehyde content in a formaldehyde aqueous solution, which is different from Example 1 in that, in step S1, nitrogen, 1000 kg of methanol vapor and 500 kg of air are introduced into an oxidation furnace containing silver flakes, and then mixed and reacted in the oxidation furnace at a temperature of 670°C and a pressure of 0.025 kg to generate formaldehyde gas.
[0039] The formaldehyde content of the formaldehyde aqueous solutions prepared in Examples 4-6 of the present application was tested, and the test results are shown in the following table.
[0040]
[0041] By analyzing the data in the above table, it can be seen that the formaldehyde content of the formaldehyde aqueous solution prepared in Examples 4-6 is as high as 50-55%, and the water content is as low as 9-12%. This shows that the formaldehyde aqueous solution prepared in Examples 4-6 of the present application has a relatively high formaldehyde content. Example
[0042] A method for increasing the formaldehyde content in a formaldehyde aqueous solution, which is different from Example 1 in that, in step S2: formaldehyde vapor is condensed to below 50°C using a multi-stage condenser to obtain condensed formaldehyde vapor. First, 1000 kg of condensed formaldehyde vapor is introduced into an absorption tower, and then 200 kg of methanol is introduced into the absorption tower, and methanol contacts and absorbs the formaldehyde vapor to obtain a formaldehyde aqueous solution. Example
[0043] A method for increasing the formaldehyde content in a formaldehyde aqueous solution, which is different from Example 1 in that, in step S2: formaldehyde vapor is condensed to below 50° C. using a multi-stage condenser to obtain condensed formaldehyde vapor. First, 1000 kg of condensed formaldehyde vapor is introduced into an absorption tower, and then 300 kg of methanol is introduced into the absorption tower, and methanol contacts and absorbs the formaldehyde vapor to obtain a formaldehyde aqueous solution. Example
[0044] A method for increasing the formaldehyde content in a formaldehyde aqueous solution, which is different from Example 1 in that, in step S2: formaldehyde vapor is condensed to below 50° C. using a multi-stage condenser to obtain condensed formaldehyde vapor. First, 1000 kg of condensed formaldehyde vapor is introduced into an absorption tower, and then 180 kg of methanol is introduced into the absorption tower, and methanol contacts and absorbs the formaldehyde vapor to obtain a formaldehyde aqueous solution.
[0045] The formaldehyde content of the formaldehyde aqueous solutions prepared in Examples 7-9 of the present application was tested, and the test results are shown in the following table.
[0046]
[0047] By analyzing the data in the above table, it can be seen that the formaldehyde aqueous solutions prepared in Examples 4, 7, and 8 have formaldehyde contents as high as 48-60%. Compared with Examples 4, 7, and 8, the formaldehyde content of the formaldehyde aqueous solution prepared in Example 9 is significantly reduced. This shows that in the method for preparing the formaldehyde aqueous solution of the present application, when the mass ratio of the condensed formaldehyde vapor and methanol is controlled to be 1:(0.2-0.3) in step S2, methanol has a better absorption effect on the formaldehyde vapor, which is conducive to obtaining a higher concentration of formaldehyde aqueous solution. Example
[0048] A method for increasing the formaldehyde content in a formaldehyde solution, which is different from Example 1 in that, in step S2, the absorption tower adopts the absorption tower prepared in Example 2. Example
[0049] A method for increasing the formaldehyde content in a formaldehyde aqueous solution, which is different from Example 1 in that, in step S2, the absorption tower adopts the absorption tower prepared in Example 3.
[0050] The formaldehyde content of the formaldehyde aqueous solutions prepared in Examples 10-11 of the present application was tested, and the test results are shown in the following table.
[0051]
[0052] By analyzing the data in the above table, it can be seen that the formaldehyde aqueous solutions prepared in Examples 10 and 11 have a formaldehyde content of up to 42-45%. However, compared with Examples 10 and 11, the formaldehyde aqueous solution prepared in Example 4 has a higher formaldehyde content. This shows that in the preparation method of the formaldehyde aqueous solution of the present application, when the absorption tower is treated with the absorption tower prepared in Example 1 in step S2, methanol has a higher absorption efficiency for formaldehyde vapor, which is conducive to obtaining a higher concentration of formaldehyde aqueous solution.
[0053] Comparative Example 1 A method for preparing a formaldehyde aqueous solution comprises the following steps: S1: water vapor, 1000kg methanol vapor and 450kg air are introduced into an oxidation furnace containing snowflake silver, and then mixed and reacted in the oxidation furnace at a temperature of 650°C and a pressure of 0.02kg to generate formaldehyde gas; S2: Condensing the formaldehyde gas to below 170°C using a condenser to obtain condensed formaldehyde gas. First, 1000 kg of condensed formaldehyde gas is introduced into an absorption tower, and then 250 kg of water is introduced into the absorption tower. The water contacts and absorbs the formaldehyde gas to obtain a formaldehyde aqueous solution.
[0054] In the comparative example of the present application, the absorption tower adopts the absorption tower prepared in Example 1, and the specific steps include: The condensed formaldehyde gas is introduced into the tower body 1 along the air inlet pipe 3, and water is introduced into the tower body 1 along the liquid inlet pipe 4. The cross-tube distributor 6 sprays the water in the liquid inlet pipe 4 onto the surface of the multi-layer corrugated mesh plate 7, where the water contacts and absorbs the rising formaldehyde gas. The generated formaldehyde aqueous solution can be discharged along the liquid outlet pipe 5, and the residual formaldehyde gas can flow back to the air inlet pipe 3 along the air outlet pipe 2 to be absorbed again.
[0055] The formaldehyde content of the formaldehyde aqueous solution prepared in Comparative Example 1 of the present application was tested, and the test results are shown in the following table.
[0056]
[0057] By analyzing the data in the above table, it can be seen that compared with the formaldehyde aqueous solution prepared in Comparative Example 1, the formaldehyde content of the formaldehyde aqueous solution prepared in Example 1 is relatively increased by 49%, and the water content is relatively reduced by 76%. This shows that the formaldehyde aqueous solution prepared in Example 1 of the present application has increased formaldehyde content, and a high-content formaldehyde aqueous solution is obtained, which has the advantages of high safety and energy saving and environmental protection.
[0058] At the same time, after the formaldehyde aqueous solutions prepared in Examples 4-11 and Comparative Example 1 were left standing at room temperature for 30 days, it was found that the formaldehyde aqueous solutions prepared in Examples 4-11 and Comparative Example 1 had no change in properties. However, after standing for 60 days, Example 8 and Comparative Example 1 agglomerated. Therefore, in the preparation method of the formaldehyde aqueous solution of the present application, a large amount of methanol is used to absorb formaldehyde gas in step S2. By controlling the methanol content, the agglomeration of the formaldehyde aqueous solution can be slowed down, which is beneficial to improving the applicability of the formaldehyde aqueous solution.
[0059] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.
Claims
1. A method for increasing the formaldehyde content in a formaldehyde solution, characterized in that: The following steps are involved: S1: In a nitrogen and catalyst environment, methanol vapor and air are mixed and reacted at 620-670°C to generate formaldehyde gas; The water content in the air is ≤2%; S2: Condensing the formaldehyde gas to below 50° C. using a condenser to obtain condensed formaldehyde gas, and then adding methanol to obtain a formaldehyde aqueous solution.
2. The method for increasing the formaldehyde content in a formaldehyde solution according to claim 1, characterized in that: In the step S1, the mass ratio of methanol vapor to air is 1:(0.4-0.5).
3. The method for increasing the formaldehyde content in a formaldehyde solution according to claim 1, characterized in that: In the step S1, the catalyst is silver flake.
4. The method for increasing the formaldehyde content in a formaldehyde solution according to claim 1, characterized in that: In the step S2, the mass ratio of the condensed formaldehyde gas to methanol is 1:(0.2-0.3).
5. The method for increasing the formaldehyde content in a formaldehyde solution according to claim 1, characterized in that: In step S2, the formaldehyde gas is first condensed to below 50° C. by a condenser, and the condensed formaldehyde gas is then introduced into an absorption tower, and finally methanol is added to obtain a formaldehyde aqueous solution; The absorption tower comprises a tower body (1), wherein the top of the tower body (1) is provided with an air outlet pipe (2), and the bottom of the tower body (1) is provided with an air inlet pipe (3); the top side wall of the tower body (1) is provided with a liquid inlet pipe (4), and the bottom side wall of the tower body (1) is provided with a liquid outlet pipe (5); a cross-tube distributor (6) is provided inside the tower body (1), and the cross-tube distributor (6) is connected to the liquid inlet pipe (4); and multiple layers of corrugated mesh plates (7) are provided inside the tower body (1), and the multiple layers of the corrugated mesh plates (7) are located at the bottom of the cross-tube distributor (6).
6. The method for increasing the formaldehyde content in a formaldehyde solution according to claim 5, characterized in that: The tower body (1) comprises an upper tower body (101) and a lower tower body (102); the cross-tube distributor (6) is located in the upper tower body (101); the corrugated mesh plate (7) is located in the upper tower body (101) and the lower tower body (102); and the height ratio of the upper tower body (101) to the lower tower body (102) is 5:
1.
7. A formaldehyde aqueous solution, characterized in that The formaldehyde solution is prepared by the method for increasing the formaldehyde content in a formaldehyde aqueous solution according to any one of claims 1 to 6.
8. The formaldehyde aqueous solution according to claim 7, characterized in that Calculated by weight percentage, it is composed of a mixture of 40-60% formaldehyde, 8-12% water and 28-52% methanol.