VOCs treatment method based on liquid metal carbon sequestration

Abstract

The invention provides a VOCs treatment method based on liquid metal carbon sequestration, and the VOCs treatment method comprises the following step: under energy excitation, VOCs and liquid metal are subjected to a contact reaction. According to the method for treating the VOCs through the liquid metal, the VOCs can be directly converted into solid carbon, secondary pollution products such as dioxin are avoided, the problem that active sites are coked and inactivated is avoided, operation is easy, the treatment effect is good, and the application value is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental application, and relates to a method for treating VOCs, and in particular to a method for treating VOCs based on liquid metal carbon fixation. Background Art

[0002] Volatile organic compounds (VOCs) are a major type of pollutant in indoor and atmospheric environments. They usually refer to low-boiling carbon-containing organic matter other than CO, CO2, carbonic acid, and metal carbon salts. They are characterized by high toxicity and complex sources. They react with NO through photochemical reactions under the influence of ultraviolet rays and other natural environments. x They work together to produce ozone in the atmosphere, further deteriorating the environment. This is a chronic disease of the modern atmosphere and indoor environment.

[0003] There are currently different ways to treat VOCs, including adsorption, combustion, and catalytic treatment. Adsorption using materials such as activated carbon and zeolite has many requirements for operating temperature and the properties of the VOCs themselves, and further treatment is required after separation, which is relatively complicated. High-temperature combustion and catalytic treatment (mostly using precious metal catalysts) both have obvious by-product problems. Incomplete oxidation of some chlorine-containing organic matter will produce more toxic and dangerous products such as dioxins; catalysts also have problems such as coking, carbon deposition, and corrosion by acidic substances in organic matter, and the T50, T90 and other temperatures of the catalyst are generally above two or three hundred degrees Celsius, and large-scale application consumes a lot of energy.

[0004] CN115282757A discloses a functionalized ionic liquid for absorbing VOCs. This functionalized ionic liquid can efficiently treat VOCs through physical dissolution absorption and chemical capture, with a removal efficiency of more than 99%. However, after the absorption is saturated, the VOCs need to be desorbed and removed before they can be recycled, and the treatment and conversion of VOCs are not fundamentally achieved.

[0005] CN116212956A prepares a metal organic framework material for photocatalytic VOCs. The metal organic framework catalyst finally degrades VOCs into small molecules such as CO2 and H2O under the catalysis of a xenon lamp. However, the generated small molecules such as CO2 need to be further processed and should not be directly discharged.

[0006] In summary, the current adsorption and catalytic treatment of VOCs faces many limitations in application. Therefore, in view of the shortcomings of the existing technology, it is necessary to provide a VOCs treatment method based on liquid metal carbon fixation. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a VOCs treatment method based on liquid metal carbon fixation, which can avoid the typical difficulties of the current VOCs treatment such as the generation of by-products and catalyst deactivation, and has high application value.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a VOCs treatment method based on liquid metal carbon fixation, the VOCs treatment method comprising:

[0010] Under energy excitation, VOCs are brought into contact with liquid metal to react.

[0011] The VOCs treatment method provided by the present invention utilizes the unique carbon polymerization ability of liquid metal under certain conditions to solidify VOCs. The process is to convert the gas phase into solid carbon by further agglomerating the carbon-metal-carbon intermediate product to produce a carbon solid product, without producing by-products such as dioxins. In addition, the fluidity of the liquid metal makes its active site non-determined, and thus does not cause the problem of coking and deactivation of the active site. The produced carbon product will naturally separate to the metal surface due to its own light density.

[0012] Preferably, the liquid metal includes a metal component having a melting point below 300°C.

[0013] Preferably, the metal component includes any one or a combination of at least two of gallium, indium, tin, lead, bismuth, zinc or cadmium. Typical but non-limiting combinations include a combination of gallium and indium, a combination of lead and bismuth, a combination of zinc and cadmium, a combination of gallium, indium and tin, a combination of bismuth, zinc and cadmium, or a combination of gallium, indium, tin, lead, bismuth, zinc and cadmium.

[0014] Preferably, the content of the metal component in the liquid metal is ≥10%, for example, it can be 10%, 15%, 20%, 30%, 50%, 70%, 90% or 100%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] Preferably, the liquid metal comprises gallium and / or gallium-indium-tin alloy.

[0016] Preferably, the energy excitation method includes using light energy and / or thermal energy.

[0017] Preferably, when the energy excitation method is thermal energy, the required temperature is 20-500°C, for example, it can be 20°C, 50°C, 100°C, 200°C, 300°C, 400°C or 500°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, when the energy excitation method is light energy, the required light intensity is 3-10 lux, for example, it can be 3 lux, 4 lux, 5 lux, 6 lux, 7 lux, 8 lux, 9 lux or 10 lux, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Further preferably, when the energy excitation method is thermal energy, the required temperature is 390-410°C, for example, it can be 390°C, 395°C, 400°C, 405°C or 410°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Further preferably, when the energy excitation method is light energy, the required light intensity is 4-6 lux, for example, it can be 4 lux, 4.5 lux, 5 lux, 5.5 lux or 6 lux, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a method for treating VOCs using liquid metal, which can directly convert VOCs into solid carbon, avoids the generation of secondary pollution products such as dioxins, and also does not cause the problem of coking and deactivation of active sites. The method has simple operation, good treatment effect and high application value. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0024] In order to clearly illustrate the technical solution of the present invention, the gas after the reaction was connected to a GC-2018 (Shimadzu, Japan) automatic chromatograph through a pipeline for analysis according to a procedure calibrated with a standard sample, and a nickel converter was equipped to distinguish CO and CO2.

[0025] Example 1

[0026] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0027] (1) In a polytetrafluoroethylene crucible, 7.83 g of metal gallium particles, 1.49 g of indium particles and 0.68 g of tin particles were mixed, placed in an electric heating mantle and heated to 250°C for 30 min. The molten metal was stirred evenly with a glass rod. After cooling to room temperature, the oxide layer on the shallow surface was mechanically removed to make the liquid metal alloy appear silver;

[0028] (2) 10 g of liquid metal alloy Ga-In-Sn was placed in a reactor, and a flow meter was used to control the total flow rate of the mixed gas of toluene and argon to 40 sccm, where the toluene concentration was 1000 ppm. The gas line was connected to the reactor to pass the liquid metal and reacted at 400°C. After 2 hours, 16.4 mg of solid carbon product was collected, and the reaction conversion rate was 8.2 mg / h.

[0029] Example 2

[0030] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0031] (1) In an alumina crucible, 4.31 g of bismuth particles, 2.35 g of lead particles and 3.34 g of tin particles were mixed, placed in an electric heating mantle and heated to 450°C for 30 min. The molten metal was stirred evenly with a glass rod. After cooling to room temperature, the oxide layer on the shallow surface was mechanically removed;

[0032] (2) 10 g of liquid metal alloy Bi-Pb-Sn was placed in a reactor, and a flow meter was used to control the total flow rate of the mixed gas of toluene and argon to 40 sccm, where the toluene concentration was 1000 ppm. The gas line was connected to the reactor to pass the liquid metal and reacted at 400°C. After 2 hours, 10.2 mg of solid carbon product was collected, and the reaction conversion rate was 5.1 mg / h.

[0033] Example 3

[0034] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0035] (1) In a polytetrafluoroethylene crucible, 7.83 g of metal gallium particles, 1.49 g of indium particles and 0.68 g of tin particles were mixed, placed in an electric heating mantle and heated to 250°C for 30 min. The molten metal was stirred evenly with a glass rod. After cooling to room temperature, the oxide layer on the shallow surface was mechanically removed to make the liquid metal alloy appear silver;

[0036] (2) 10 g of liquid metal alloy Ga-In-Sn alloy was placed in a reactor, and 40 sccm of toluene-argon mixed gas was introduced at 20°C, where the toluene concentration was 1000 ppm. After 2 hours, 4.7 mg of solid carbon product was collected, and the reaction conversion rate was 2.35 mg / h.

[0037] Example 4

[0038] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0039] (1) In a polytetrafluoroethylene crucible, 7.83 g of metal gallium particles, 1.49 g of indium particles and 0.68 g of tin particles were mixed, placed in an electric heating mantle and heated to 250°C for 30 min. The molten metal was stirred evenly with a glass rod. After cooling to room temperature, the oxide layer on the shallow surface was mechanically removed to make the liquid metal alloy appear silver;

[0040] (2) 10 g of liquid metal alloy Ga-In-Sn alloy was placed in a reactor, and 40 sccm of formaldehyde-nitrogen mixed gas was introduced at 20°C, where the formaldehyde concentration was 50 ppm. After 10 hours, 2.3 mg of solid carbon product was collected, and the reaction conversion rate was 0.23 mg / h.

[0041] Example 5

[0042] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0043] (1) In a polytetrafluoroethylene crucible, 7.83 g of metal gallium particles, 1.49 g of indium particles and 0.68 g of tin particles were mixed, placed in an electric heating mantle and heated to 250°C for 30 min. The molten metal was stirred evenly with a glass rod. After cooling to room temperature, the oxide layer on the shallow surface was mechanically removed to make the liquid metal alloy appear silver;

[0044] (2) 10 g of liquid metal alloy Ga-In-Sn alloy was placed in a quartz cylindrical reactor, and 40 sccm of toluene-argon mixed gas was introduced into the quartz cylindrical reactor, where the toluene concentration was 1000 ppm. A 500 W xenon lamp was used for irradiation, and the light was adjusted to 5 lux with the help of an optical power meter. After 2 hours, 7.2 mg of solid carbon product was collected, and the reaction conversion rate was 3.6 mg / h.

[0045] Example 6

[0046] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0047] (1) In a polytetrafluoroethylene crucible, metal gallium particles and indium particles were mixed in a gallium to indium mass ratio of 3:1, placed in an electric heating mantle and heated to 250°C for 30 minutes, the molten metal was stirred evenly with a glass rod, and after cooling to room temperature, the oxide layer on the shallow surface was mechanically removed;

[0048] (2) 10 g of liquid metal alloy Ga-In alloy was placed in a reactor, and 40 sccm of a xylene-argon mixed gas was introduced at 20°C, where the xylene concentration was 500 ppm. After 2 hours, 2.1 mg of solid carbon product was collected, and the reaction conversion rate was 1.06 mg / h.

[0049] Example 7

[0050] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0051] (1) In a polytetrafluoroethylene crucible, metal gallium particles and indium particles were mixed in a gallium to indium mass ratio of 3:1, placed in an electric heating mantle and heated to 250°C for 30 minutes, the molten metal was stirred evenly with a glass rod, and after cooling to room temperature, the oxide layer on the shallow surface was mechanically removed;

[0052] (2) 10 g of liquid metal alloy Ga-In-Sn alloy was placed in a reactor, and 40 sccm of formaldehyde-nitrogen mixed gas was introduced at 500°C, where the formaldehyde concentration was 50 ppm. After 10 hours, 0.8 mg of solid carbon product was collected, and the reaction conversion rate was 0.08 mg / h.

[0053] Example 8

[0054] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0055] (1) In a polytetrafluoroethylene crucible, metal gallium particles and indium particles were mixed in a gallium to indium mass ratio of 3:1, placed in an electric heating mantle and heated to 250°C for 30 minutes, the molten metal was stirred evenly with a glass rod, and after cooling to room temperature, the oxide layer on the shallow surface was mechanically removed;

[0056] (2) 10 g of liquid metal alloy Ga-In-Sn alloy was placed in a quartz cylindrical reactor, and 40 sccm of toluene-argon mixed gas was introduced into the quartz cylindrical reactor, wherein the toluene concentration was 1000 ppm. A 500 W xenon lamp was used for irradiation, and the light power was adjusted to 3 lux with the help of an optical power meter. After 2 hours, 5.3 mg of solid carbon product was collected, and the reaction conversion rate was 2.65 mg / h.

[0057] Example 9

[0058] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation, and the VOCs treatment method comprises the following steps:

[0059] (1) In a polytetrafluoroethylene crucible, metal gallium particles and indium particles were mixed in a gallium to indium mass ratio of 3:1, placed in an electric heating mantle and heated to 250°C for 30 minutes, the molten metal was stirred evenly with a glass rod, and after cooling to room temperature, the oxide layer on the shallow surface was mechanically removed;

[0060] (2) Take 10g of liquid metal alloy Ga-In-Sn alloy and place it in a quartz cylindrical reactor. Pass 40sccm of toluene-argon mixed gas into the quartz cylindrical reactor, where the toluene concentration is 1000ppm. Use a 500W xenon lamp for irradiation, and adjust it to 10lux with the help of an optical power meter. After 2 hours, 7.4mg of solid carbon product is collected, and the reaction conversion rate is 3.7mg / h. The higher the light intensity, the greater the reflection waste, and the performance improvement is not obvious.

[0061] Example 10

[0062] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation. Compared with Example 1, the reaction temperature of step (2) is 10°C, and the rest is the same as Example 1. The metal undergoes a phase change and the reaction cannot proceed.

[0063] Embodiment 11

[0064] This embodiment provides a VOCs treatment method based on liquid metal carbon fixation. Compared with Example 1, the reaction temperature of step (2) is 520°C, and the rest is the same as Example 1. 16.9 mg of carbon product is collected in 2 hours. The improvement is slight because the toluene conversion rate based on GaInSn metal has exceeded 90% at 400°C. Limited by the gas-liquid contact efficiency, there is very little room for improvement.

[0065] Comparative Example 1

[0066] This comparative example provides a metal-based VOCs treatment method, which comprises the following steps:

[0067] In a fume hood, mercury and copper powder were mixed in a 1:1 mass ratio and ground into a mercury-copper alloy, which was then transferred to a reactor. A toluene-argon mixed gas was introduced at 200°C, wherein the toluene concentration was 1000 ppm. No product was found, and chromatographic analysis of the tail gas showed that no conversion reaction occurred.

[0068] Table 1

[0069]

[0070]

[0071] “—” in the table means no data.

[0072] As can be seen from Table 1, the VOCs treatment method provided by the present invention can directly convert VOCs gas into solid carbon products without producing dioxins as byproducts, can treat VOCs gas with a concentration as low as 50 ppm, and will not cause the problem of metal deactivation during long-term reaction, and has a good treatment effect; when the preferred treatment conditions of the present invention are adopted, the conversion rate is significantly improved, and the conversion effect is good.

[0073] In summary, the present invention provides a method for treating VOCs using liquid metal, which can directly convert VOCs into solid carbon, avoid the production of secondary pollution products such as dioxins, and will not cause the problem of coking and deactivation of active sites. It has simple operation, good treatment effect and high application value.

[0074] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A VOCs treatment method based on liquid metal carbon fixation, characterized in that: The VOCs treatment method comprises: Under energy excitation, VOCs are brought into contact with liquid metal to react.

2. The VOCs treatment method according to claim 1, characterized in that: The liquid metal includes a metal component having a melting point below 300°C.

3. The VOCs treatment method according to claim 2, characterized in that: The metal component includes any one of gallium, indium, tin, lead, bismuth, zinc or cadmium, or a combination of at least two thereof.

4. The VOCs treatment method according to claim 2 or 3, characterized in that: The content of metal components in the liquid metal is ≥10%.

5. The VOCs treatment method according to any one of claims 1 to 4, characterized in that: The liquid metal includes gallium and / or gallium-indium-tin alloy.

6. The VOCs treatment method according to any one of claims 1 to 5, characterized in that: The energy excitation method includes using light energy and / or thermal energy.

7. The VOCs treatment method according to claim 6, characterized in that: When the energy excitation method is thermal energy, the required temperature is 20-500°C.

8. The VOCs treatment method according to claim 6, characterized in that: When the energy excitation method is light energy, the required light intensity is 3-10 lux.

9. The VOCs treatment method according to claim 6, characterized in that: When the energy excitation method is thermal energy, the required temperature is 390-410°C.

10. The VOCs treatment method according to claim 6, characterized in that: When the energy excitation method is light energy, the required light intensity is 4-6 lux.

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