A method for treating organic chlorine by-products

Abstract

The application discloses a treatment method of organic chlorine by-products, and belongs to the field of catalysts. In view of the treatment problem of the organic chlorine by-products, the application provides a porous carrier catalyst loaded with tantalum, which can catalytically decompose the organic chlorine by-products into carbon, hydrogen and HCl. The carbon attached to the surface of the catalyst can be removed through air calcination, and the catalyst can be reused after the carbon is removed. The mixed gas of hydrogen and HCl uses ethylene glycol or glycerol as an absorbent, so that the HCl is absorbed and dissolved in the absorbent, and the separation purpose is achieved. After separation, the hydrogen is used as fuel.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalysts, and particularly relates to a treatment method of organic chlorine byproducts. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general background of the application and does not necessarily constitute an admission or a recognition that the information forms part of the prior art already known to a person of ordinary skill in the art.

[0003] Chlorine (Cl2) is one of the top ten basic raw materials for producing chemicals, and is widely used. In 2020, the global Cl2 production reached 100 million tons, and the domestic production reached 55 million tons, ranking first in the world. With the development of chlor-alkali industry, the production capacity of organic chlorine chemicals is expanding rapidly, and the accompanying organic chlorine byproducts are also increasing rapidly. For example, more than 90% of chloropropylene in the world is produced by high-temperature chlorination of propylene, and the domestic production has reached more than 1.2 million tons in 2023.

[0004] In the process of producing chloropropylene by high-temperature chlorination of propylene, the yield of chloropropylene is about 80%, and the remaining 20% is the accompanying organic chlorine byproduct, commonly known as D,D-mixture, which mainly contains 1,2-dichloropropane, 1,3-dichloropropylene, 3,3-dichloropropylene and other chlorine-containing organic compounds (as shown in Table 1). At present, the D,D-mixture byproduct in China has reached 300-500 thousand tons per year. Due to the low added value, it is difficult to be absorbed by the market, and it is difficult to burn and treat, with high equipment investment. The decomposition gas produced has little value. Similarly, in the production process of chloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethane and other polychlorinated byproducts are also produced. These byproducts are increasing year by year, which is extremely harmful to human health and the environment, and the treatment cost is high. It is urgent to find a new and more economical and environmentally friendly way to solve the problem of organic chlorine byproduct treatment. SUMMARY

[0005] In order to solve the problems of the prior art, the purpose of the present application is to provide a treatment method of organic chlorine byproducts. The present application provides a method for decomposing organic chlorine byproducts into carbon, hydrogen and hydrogen chloride by using a porous support catalyst loaded with tantalum. The porous support catalyst loaded with tantalum has high catalytic activity and good stability, and hydrogen and hydrogen chloride can be separated by using ethylene glycol or glycerol as an absorbent.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] In the first aspect of the present application, a preparation method of a porous support catalyst loaded with tantalum is provided, which comprises the following steps:

[0008] The porous carrier is immersed in a solution containing tantalum salt, and after being taken out and dried, the porous carrier is immersed for multiple times to make the loading amount of tantalum salt reach more than 10%; the porous carrier loaded with tantalum salt is calcined in a hydrogen atmosphere at 500-700 ℃ for 10-15 h, and the tantalum-loaded porous carrier catalyst is obtained after being cooled.

[0009] In a second aspect of the present application, the tantalum-loaded porous carrier catalyst is prepared by the method as described above.

[0010] In a third aspect of the present application, the tantalum-loaded porous carrier catalyst as described above is applied to catalytic decomposition of organic chlorine by-products.

[0011] In a fourth aspect of the present application, a treatment method of organic chlorine by-products is provided, which comprises the following steps: the organic chlorine by-products are vaporized in an oxygen-free atmosphere, and then a gas-solid phase reaction occurs between the vaporized organic chlorine by-products and the tantalum-loaded porous carrier catalyst, so that the organic chlorine by-products are catalytically decomposed, and the decomposition products include carbon, hydrogen and HCl.

[0012] The present application has the following advantages:

[0013] (1) The tantalum-loaded porous carrier catalyst of the present application has a simple preparation process, and is obtained through simple immersion and calcination. In addition, the porous carrier is used, so that the catalyst has a large specific surface area and can adsorb more tantalum salt, and thus the prepared catalyst has the characteristics of high activity and high stability.

[0014] (2) The tantalum-loaded porous carrier catalyst of the present application can catalytically decompose organic chlorine by-products, and the decomposition products include carbon, hydrogen and hydrogen chloride gas. The conversion rate of the organic chlorine by-products reaches more than 94%, the yield of hydrogen chloride reaches 90%-98%, and the yield is very high. In addition, the effective separation of hydrogen and hydrogen chloride can be quickly realized by using ethylene glycol or glycerol as an absorbent, which is conducive to the recycling and reuse of hydrogen chloride and hydrogen.

[0015] (3) The treatment method of organic chlorine by-products provided by the present application is economic and environmentally friendly, realizes the resource utilization of organic chlorine by-products, and solves the problem of difficult treatment of organic chlorine by-products. BRIEF DESCRIPTION OF DRAWINGS

[0016] The drawings constituting a part of the specification of the present application serve to provide a further understanding of the present application, and the schematic embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application.

[0017] Figure 1 It is an electron microscope photo of the silicon carbide carrier;

[0018] Figure 2 It is an electron microscope photo of the tantalum-loaded silicon carbide catalyst prepared in Example 1. DETAILED DESCRIPTION

[0019] In order to solve the problem of treating organic chlorine by-products, the present application provides a method for treating organic chlorine by-products, which uses a tantalum-loaded porous carrier catalyst to catalytically decompose the organic chlorine by-products into carbon, hydrogen and HCl. The carbon attached to the surface of the catalyst can be removed by air calcination, and the catalyst can be reused after removing the carbon. The hydrogen and HCl mixed gas uses ethylene glycol or glycerol as an absorbent to dissolve the HCl in the absorbent to achieve the purpose of separation, and the hydrogen is used as fuel after separation.

[0020] In a typical embodiment of the present application, a method for preparing a tantalum-loaded porous carrier catalyst is provided, which comprises the following steps:

[0021] The porous carrier is immersed in a solution containing tantalum salt, and after being taken out and dried, the porous carrier is immersed multiple times to make the loading amount of tantalum salt reach more than 10%. The porous carrier loaded with tantalum salt is calcined in a hydrogen atmosphere at 500-700°C for 10-15h, and the tantalum-loaded porous carrier catalyst is obtained after cooling.

[0022] In some embodiments of this embodiment, the porous carrier includes silicon carbide, lapis lazuli honeycomb ceramic, alumina, clay honeycomb, kaolin honeycomb, silicon oxide honeycomb and titanium oxide honeycomb. The porous carrier has a large specific surface area, can adsorb more tantalum salt, and the obtained catalyst has higher activity and better stability.

[0023] In some embodiments of this embodiment, the tantalum salt includes tantalum pentachloride, tantalum nitrate, tantalum pentafluoride, tantalum acid, sodium tantalate and potassium heptafluorotantalate.

[0024] In some embodiments of this embodiment, the heating rate during calcination is 5-15°C / min, and preferably 10°C / min.

[0025] In some embodiments of this embodiment, the porous carrier is calcined in a hydrogen atmosphere at a heating rate of 10°C / min to 600°C for 12h, and the tantalum-loaded porous carrier catalyst is obtained after natural cooling to room temperature.

[0026] In a second aspect of the present application, a tantalum-loaded porous carrier catalyst obtained by the method for preparing the tantalum-loaded porous carrier catalyst described above is provided.

[0027] In a third aspect of the present application, the tantalum-loaded porous carrier catalyst described above is used in catalytic decomposition of organic chlorine by-products.

[0028] In a fourth aspect of the present application, a method for treating organic chlorine by-products is provided, which comprises the following steps: after the organic chlorine by-products are vaporized in an oxygen-free atmosphere, a gas-solid phase reaction occurs with the tantalum-loaded porous carrier catalyst described above to catalytically decompose the organic chlorine by-products, and the decomposition products include carbon, hydrogen and HCl.

[0029] In some embodiments of the embodiment, the organic chlorine by-products include, but are not limited to, organic chlorine by-products produced in the process of high-temperature chlorination of propylene to produce chloropropylene, and organic chlorine by-products produced in the process of vinyl chloride production. The tantalum-loaded porous carrier catalyst of the present application has universality and can catalyze the decomposition of the organic chlorine by-products into carbon, hydrogen and hydrogen chloride in an oxygen-free atmosphere, so as to realize efficient treatment of the organic chlorine by-products.

[0030] In some embodiments of the embodiment, the gas-solid phase reaction temperature is 250-700℃, preferably 300℃.

[0031] In some embodiments of the embodiment, after the reaction is completed, the carbon is attached to the surface of the catalyst and is removed by air calcination; the hydrogen and HCl mixed gas uses ethylene glycol or glycerol as an absorbent to absorb and dissolve HCl in the absorbent to achieve the purpose of separation, and the separated hydrogen can be used as fuel. The catalyst after carbon removal can be reused.

[0032] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific embodiments.

[0033] Embodiment 1

[0034] A preparation method of a tantalum-loaded porous carrier catalyst, comprising the following steps:

[0035] 10g of tantalum pentachloride is dissolved in 200mL of alcohol, 50g of silicon carbide is used as a carrier (Φ30mm*30mm, porosity:<20%, density:2.4-2.6g / mL), the carrier is immersed in the alcohol solution for 10h, and then naturally air-dried and immersed multiple times, so that the loading amount of tantalum pentachloride reaches more than 10%. Vacuum drying is performed at 80℃ for 12h, and then calcination is performed in a tube furnace under a hydrogen atmosphere (100mL / min) at a temperature rising speed of 10℃ / min to 600℃ for 12h. Natural cooling to room temperature is performed for standby use. Figure 1 An electron microscope photo of the silicon carbide carrier, Figure 2 An electron microscope photo of the tantalum-loaded silicon carbide catalyst prepared in Embodiment 1.

[0036] Embodiment 2

[0037] A preparation method of a tantalum-loaded porous carrier catalyst, which is different from Embodiment 1 in that aluminum oxide is used as a carrier, and the size specification of the carrier is: Φ3.0-5.0mm, bulk density: 0.68-0.85g / ml, specific surface area: 200-280m 2 / g, pore volume: 0.4-0.5ml / g.

[0038] Embodiment 3

[0039] A method for preparing a tantalum-loaded porous carrier catalyst, which is different from example 1 in that a clay honeycomb is used as the carrier, with the size specifications being: Φ30mm*30mm, wall thickness: 0.12-0.2mm, hole width: 0.81-0.87mm, hole area: 0.65-0.75mm 2 , open porosity: 61-80%, density: 0.68g / mL.

[0040] Example 4

[0041] A method for preparing a tantalum-loaded porous carrier catalyst, which is different from example 1 in that a kaolin honeycomb is used as the carrier, with the size specifications being: Φ30mm*30mm, wall thickness: 0.1-0.2mm, hole width: 0.7-0.77mm, hole area: 0.5-0.65mm 2 , open porosity: 50-60%, density: 0.62g / mL.

[0042] Example 5

[0043] A method for preparing a tantalum-loaded porous carrier catalyst, which is different from example 1 in that a lapis lazuli honeycomb ceramic is used as the carrier, with the size specifications being: Φ30mm*30mm, wall thickness: 0.17-0.23mm, hole width: 0.81-0.87mm, hole area: 0.65-0.75mm 2 , open porosity: <61-70%, density: 0.58g / mL.

[0044] Example 6

[0045] A method for preparing a tantalum-loaded porous carrier catalyst, which is different from example 1 in that a silicon oxide honeycomb is used as the carrier, with the size specifications being: Φ30mm*30mm, wall thickness: 0.13-0.23mm, hole width: 0.81-0.89mm, hole area: 0.61-0.79mm 2 , open porosity: 56-75%, density: 0.78g / mL.

[0046] Example 6

[0047] A method for preparing a tantalum-loaded porous carrier catalyst, which is different from example 1 in that a titanium oxide honeycomb is used as the carrier, with the size specifications being: Φ30mm*30mm, wall thickness: 0.12-0.23mm, hole width: 0.61-0.88mm, hole area: 0.6-0.71mm 2 , open porosity: 51-75%, density: 0.68g / mL.

[0048] Example 7

[0049] D, D-mixture is generated in the process of propylene high-temperature chlorination to prepare chloropropylene, and main components of the D, D-mixture are shown in Table 1.

[0050] Table 1 Main components of the D, D-mixture

[0051]

[0052] A treatment method of an organic chlorine byproduct, comprising the following steps:

[0053] Under the conditions shown in Table 2, the D, D-mixture is vaporized in a preheated buffer tube (250℃, Φ50mm*300mm) under an oxygen-free atmosphere, and is introduced into a catalyst bed (Φ30mm*150mm) containing the tantalum-loaded zeolite honeycomb ceramic catalyst prepared in Example 1 to perform a reaction. The tail gas is collected after heat exchange by a cold trap, and the gas is collected by a gas bag. After the gas is absorbed by lye, it is weighed to know that HCl:H2=1:4.3 (molar ratio), and the activated carbon product:HCl=1:1 (molar ratio), containing 3-5% C 1-3 hydrocarbons and tar. As shown in Table 2, no water is generated in the reaction, the product is discharged in the form of a mixed gas of HCl and hydrogen, and the conversion rate of the D, D-mixture is ≥95%.

[0054] After the reaction is completed, the reaction system is purged by nitrogen (N2: 500mL / min), the tail gas is switched to lye absorption and discharge, the temperature is increased to 600℃ at a rate of 10℃ / min, and then is switched to air (air: 500mL / min). The carbon is removed by calcination for 12h, the purging is stopped after natural cooling to the reaction temperature, the D, D-mixture dechlorination reaction is repeated multiple times, and the results are shown in Table 2. The catalyst activity is stable, and the catalyst can be repeatedly used multiple times.

[0055] Table 2 Experimental results of the catalyst prepared in Example 1 in catalyzing decomposition of the D, D-mixture to recover HCl

[0056]

[0057] The tail gas HCl:H2=1:4.3 (molar ratio) is connected to a flask containing ethylene glycol (5ml), and is stirred for 12h. After the experiment is completed, the weight of the ethylene glycol is weighed, and the absorption rate is 32%. The ethylene glycol is heated at 150℃ for 30 minutes under stirring, and the HCl gas release rate is 97%. Through the above process, the effective separation of HCl gas from the mixed gas of HCl and hydrogen can be realized.

[0058] Example 8

[0059] A treatment method of an organic chlorine byproduct, which is different from Example 7 in that the reaction is performed by using the catalyst bed of the tantalum-loaded porous support catalyst prepared in Examples 2, 3, 4, 5 and 6. The results are shown in Table 3.

[0060] Table 3 Experimental results of catalyst prepared in Example 2-6 catalyzing decomposition of D, D-mixture to recover HCl

[0061]

[0062] Example 9

[0063] Using analytical pure 1,1,1-trichloroethane, 1,1,2-trichloroethane, mixtures were prepared in proportions shown in Table 4 to simulate organic chlorine by-products produced in vinyl chloride process.

[0064] Table 4 Composition table of organic chlorine by-products

[0065] Component Content (%) 1,1,1-trichloroethane 50 1,1,2-trichloroethane 1,1,1,2-tetrachloroethane 50

[0066] A method for treating organic chlorine by-products, using the organic chlorine by-products shown in Table 4 instead of D, D-mixture in Example 7, and the remaining reaction steps are the same as Example 7.

[0067] After detection, the HCl:H2 ratio in the tail gas was 20:1 (molar ratio), the activated carbon product:HCl ratio was 1:3 (molar ratio), and the gaseous C content was about 3% 1-3 hydrocarbons and tar.

[0068] After the reaction was completed, the reaction system was purged with nitrogen (N2: 500 mL / min), the tail gas was switched to alkaline solution absorption and discharge, the temperature was increased to 600°C at a rate of 10°C / min, and the air was switched to air (air: 500 mL / min), and calcined for 12 h to remove carbon. After natural cooling to the reaction temperature, the purging was stopped, and the dechlorination reaction of the organic chlorine by-products shown in Table 4 was repeated multiple times, and the results are shown in Table 5. The catalyst activity was stable and could be used repeatedly.

[0069] Table 5 Experimental results of catalyst prepared in Example 1 catalyzing recovery of HCl from organic chlorine by-products shown in Table 4

[0070]

[0071] The tail gas HCl:H2 ratio was 20:1 (molar ratio), and the flask containing ethylene glycol (5 ml) was connected, and stirred for 12 h. After the experiment was completed, the weight of the ethylene glycol was measured, and the absorption rate was 47%. The above ethylene glycol was heated at 150°C for 30 minutes with stirring, and the HCl gas release rate was 98%. Through the above process, effective separation of HCl gas from the mixed gas of HCl and hydrogen can be achieved.

[0072] Example 10

[0073] A method for treating organic chlorine by-products, which is different from Example 10 in that the reaction is carried out using a catalyst bed of tantalum-loaded porous support catalyst prepared in Examples 2, 3, 4, 5, and 6. The results are shown in Table 6.

[0074] Table 6 Experimental results of catalyst prepared in Example 2-6 for recovering HCl from organic chlorine by-products shown in Table 4

[0075]

[0076] Example 11

[0077] A method for treating organic chlorine by-products, which is different from Example 9 is that a gas bag (10 L) full of HCl gas is connected to a flask containing glycerol (5 ml) under stirring for 12 h.

[0078] After the experiment, the weight of glycerol is measured, and the absorption rate is 31%. The above glycerol is heated at 150°C under stirring for 30 min, and the HCl gas release rate is 99%. Through the above process, the effective separation of HCl gas from the mixed gas of HCl and hydrogen can be achieved.

[0079] Comparative Example 1

[0080] A gas bag (10 L) full of HCl gas is connected to a flask containing ethylene glycol (5 ml) under stirring for 12 h. After the experiment, the weight of ethylene glycol is measured, and the absorption rate is 48%. The above ethylene glycol is heated at 150°C under stirring for 30 min, and the HCl gas release rate is 98%. Through the above process, the absorption and storage of HCl gas and the release by heating can be achieved.

[0081] Comparative Example 2

[0082] In Comparative Example 1, HCl is replaced by hydrogen, and the other steps are the same. The mass of ethylene glycol does not change, and there is no absorption of hydrogen.

[0083] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. The application of a tantalum-supported porous catalyst in the catalytic decomposition of organochlorine byproducts, characterized in that, The preparation method of the tantalum-supported porous catalyst includes the following steps: The porous support is immersed in a solution containing tantalum salt, and after being taken out and dried, it is immersed repeatedly to achieve a tantalum salt loading of more than 10%. The porous support loaded with tantalum salt is calcined in a hydrogen atmosphere at 500-700℃ for 10-15 h, and after cooling, the tantalum-supported porous support catalyst is obtained. The porous carrier includes silicon carbide, cordierite honeycomb ceramic, alumina, clay honeycomb, kaolin honeycomb, silicon dioxide honeycomb, or titanium dioxide honeycomb.

2. The application as described in claim 1, characterized in that, The cordierite honeycomb ceramic has a pore width of 0.81-0.87 mm and a pore area of ​​0.65-0.75 mm². 2 It has an open porosity of less than 61-70% and a density of 0.58 g / mL.

3. The application as described in claim 1, characterized in that, The tantalum salts include tantalum pentachloride, tantalum nitrate, tantalum pentafluoride, tantalum acid, sodium tantalate, or potassium heptafluorotantalate.

4. The application as described in claim 1, characterized in that, The heating rate during calcination is 5-15℃ / min.

5. The application as described in claim 4, characterized in that, In a hydrogen atmosphere, the temperature is increased to 600℃ and calcined for 12 h at a heating rate of 10℃ / min, and then naturally cooled to room temperature to obtain the tantalum-supported porous catalyst.

6. The application as described in claim 1, characterized in that, The method for treating organochlorine byproducts includes the following steps: after the organochlorine byproducts are vaporized in an oxygen-free atmosphere, they undergo a gas-solid phase reaction with the tantalum-supported porous catalyst to catalytically decompose the organochlorine byproducts. The decomposition products include carbon, hydrogen, and HCl.

7. The application as described in claim 6, characterized in that, The organochlorine byproducts include organochlorine byproducts generated during the high-temperature chlorination of propylene to produce chloropropylene, and organochlorine byproducts generated during the production of vinyl chloride. The reaction temperature for gas-solid phase reactions is 250-700℃; After the reaction is complete, the carbon adhering to the catalyst surface is removed by calcination in air; the hydrogen and HCl mixture is separated by using ethylene glycol or glycerol as an absorbent to absorb and dissolve the HCl in the absorbent.

8. The application as described in claim 7, characterized in that, The reaction temperature for the gas-solid phase reaction is 300℃.

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