Preparation and application of Pd-M / C catalyst

Abstract

The invention relates to the technical field of Pd-M / C catalysts, in particular to preparation and application of a Pd-M / C catalyst, the Pd-M / C catalyst comprises a main active component, an auxiliary element M and a carrier C. The main active component is precious metal Pd, the auxiliary element M is at least one of K, Mg and Ba, and the carrier C is at least one of activated carbon and carbon black; the preparation method comprises the following steps: pretreating the carrier C, preparing a catalyst intermediate, preparing a catalyst precursor and reducing; according to the present invention, palladium is adopted as the main catalyst, such that the catalytic performance is improved, the carrier C is pretreated so as to enhance the interaction between the carrier and the active component, the dispersity of the active component is improved, the catalyst has high activity under the condition of low palladium loading capacity, and the auxiliary agent M is added to reduce the carbon deposition amount of the catalyst so as to improve the catalytic performance of the catalyst; the stability of the catalyst is improved.

Description

Technical Field

[0001] The invention relates to the technical field of Pd-M / C catalysts, and in particular to the preparation and application of a Pd-M / C catalyst. Background Art

[0002] There are many types of chlorofluorocarbons (CFCs) and they are widely used in many fields, such as refrigerants, foaming agents, etc. However, the Cl atoms in chlorofluorocarbons will react with ozone, thus causing a hole in the ozone layer. Therefore, China has actively responded to the global call for environmental protection, and has confiscated, collected or stockpiled a large amount of chlorofluorocarbons, and then used high-temperature incineration methods for harmless disposal. However, direct incineration not only consumes a lot of energy, but also wastes CF bond resources.

[0003] Therefore, there are inventions such as the hydrodechlorination catalyst disclosed in the invention patent with publication number CN101632931B and the method for preparing monofluoromethane disclosed in the invention patent with publication number CN104016829A, which recover the CF bond resources.

[0004] However, it was found during use that the existing preparation method has a complicated preparation process and high cost. In addition, it was found during application that the catalytic effect is poor, and the stability during the hydrodechlorination reaction of different types of waste chlorofluorocarbons is also poor. Therefore, there is an urgent need for the preparation of a Pd-M / C catalyst and its application to improve the above problems. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a catalyst with improved catalytic performance by using palladium as the main catalyst, and the catalyst pre-treats the carrier C to enhance the interaction between the carrier and the active component, improve the dispersion of the active component, and has higher activity under the condition of low palladium loading. At the same time, by adding an auxiliary agent M, the carbon deposition amount of the catalyst is reduced, and the stability of the catalyst is improved. Secondly, when the catalyst is used for the hydrodechlorination reaction of different types of waste chlorofluorocarbons, the catalytic hydrodechlorination reaction temperature is good, and when the reaction is carried out at a temperature of 200-500°C, it shows high activity and selectivity, and the resource utilization rate of single and mixed waste chlorofluorocarbons can reach more than 50%. In addition, the catalyst preparation method is simple, the operation is simple, and the catalyst has high catalytic activity, high selectivity, good stability and mild reaction conditions, and is convenient for the preparation and application of a Pd-M / C catalyst in industrial production.

[0006] The preparation of a Pd-M / C catalyst of the present invention comprises a main active component, an auxiliary element M and a carrier C, wherein the main active component is the precious metal Pd, the auxiliary element M is at least one of K, Mg and Ba, and the carrier C is at least one of activated carbon and carbon black;

[0007] The preparation steps include:

[0008] S1. Pre-treating the carrier C: firstly subjecting the carrier C to an acid treatment, then washing it to neutrality and drying it for later use;

[0009] S2, preparing a catalyst intermediate: after ultrasonic treatment, dropwise adding a soluble palladium salt solution onto the pretreated carrier of S1 for impregnation, and drying to obtain a catalyst intermediate;

[0010] S3, preparing a catalyst precursor: adding the additive M precursor dropwise to the catalyst intermediate of S2 for impregnation;

[0011] S4, reduction: reducing the catalyst in S3 under a reducing atmosphere for 2-4 hours to obtain a supported hydrodechlorination catalyst Pd-M / C;

[0012] Preferably, the specific operation steps of pre-treating the carrier C in S1 are as follows:

[0013] S1-1, placing carrier C in a hydrochloric acid solution with a volume concentration of 10-40% and a solid-liquid ratio of 1:10-15, stirring and refluxing at 60-100° C. for 3-9 hours;

[0014] S1-2. Wash the carrier C treated with hydrochloric acid with distilled water until it becomes neutral, and dry it at 70-130° C. for 6-14 hours.

[0015] Preferably, the mass concentration of the soluble palladium salt solution in S2 is 1-6%, and it is palladium chloride, palladium nitrate or palladium acetate. The ultrasonic time of the soluble palladium salt solution is 5-15 minutes, the immersion time is 12-28 hours, the drying temperature is 80-120°C, and the drying time is 6-14 hours.

[0016] Preferably, the M precursor of the S3 process is at least one of potassium chloride, magnesium chloride and barium nitrate, the immersion time is 12-28 hours, the drying temperature is 80-120° C., and the drying time is 6-14 hours.

[0017] Preferably, the reducing atmosphere in S4 is hydrogen, the reducing temperature is 200-400° C., and the reducing gas flow rate is 15-30 ml / min.

[0018] A Pd-M / C catalyst is used in the hydrodechlorination reaction of different types of waste chlorofluorocarbons.

[0019] Preferably, the catalytic reaction is carried out in a fixed bed reaction device, the catalyst is loaded into the fixed bed reaction device, the temperature is raised to the reaction temperature, and H 2 React with the raw material mixed gas of waste chlorofluorocarbons, the reaction temperature is 200-500℃, the reaction pressure is normal pressure, and the space velocity of the raw material mixed gas is 100-1000h -1 .

[0020] Preferably, the H 2 The ratio of the feed volume flow rate to that of chlorofluorocarbons is 1-4:1.

[0021] Preferably, the waste chlorofluorocarbons are single C1 chlorofluorocarbons, C2 chlorofluorocarbons and mixed chlorofluorocarbons.

[0022] Preferably, the C1 type fluorochlorocarbon is dichlorofluoromethane, the C2 type fluorochlorocarbon is tetrafluoroethylene dichloroethane, and the mixed fluorochlorocarbon is dichlorofluoromethane + tetrafluoroethylene dichloroethane.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The catalytic performance is improved by using palladium as the main catalyst, and the catalyst is pretreated by the carrier C to enhance the interaction between the carrier and the active component, improve the dispersion of the active component, and have higher activity under the condition of low palladium loading. At the same time, by adding the additive M, the carbon deposition of the catalyst is reduced, and the stability of the catalyst is improved;

[0025] 2. When the catalyst is used for the hydrodechlorination reaction of different types of waste chlorofluorocarbons, the catalytic hydrodechlorination reaction temperature is good. When the reaction temperature is 200-500°C, it shows high activity and selectivity, and the resource utilization rate of single and mixed waste chlorofluorocarbons ((yield of resource-usable products = conversion rate × selectivity of main products)) can reach more than 50%;

[0026] 3. The catalyst preparation method is simple, the operation is simple, and it has high catalytic activity, high selectivity, good stability and mild reaction conditions, which is convenient for application in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a TEM image of the catalyst in Example 2 of the present invention;

[0028] Figure 2 is a TEM image of the catalyst in Example 3 of the present invention;

[0029] Figure 3 is a TEM image of the catalyst in Example 4 of the present invention;

[0030] Figure 4 This is a TEM image of the catalyst in Example 5 of the present invention. DETAILED DESCRIPTION

[0031] In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0032] Example 1

[0033] The preparation of Pd / C catalyst (carrier C is untreated) specifically comprises the following steps:

[0034] S1. Weigh 0.9 g of palladium chloride and add 2 mL of hydrochloric acid to prepare a chloropalladium acid solution;

[0035] S2, weigh 0.06g of the prepared chloropalladic acid solution and dissolve it in 2.7mL of deionized water, then drop the solution evenly onto 3g of untreated activated carbon, ultrasonically treat for 15min, let stand for 24h, and then put it in a 120℃ oven to dry for 12h;

[0036] S3. Reduce the catalyst in a hydrogen atmosphere for 2 h at a reduction temperature of 250° C. and a hydrogen flow rate of 15 mL / min to obtain a Pd / C catalyst, named Pd / C.

[0037] Example 2

[0038] The preparation of Pd / C catalyst (carrier C is pretreated with HCl) specifically comprises the following steps:

[0039] S1. Take 30g of activated carbon and place it in a 500mL round-bottom flask. Stir the activated carbon in a 37% hydrochloric acid solution with magnetic stirring for 6h. The stirring temperature is 80℃ and the speed is 500r / min. Then wash it with 100℃ deionized water until it is neutral, put it in a 120℃ oven to dry for 12h and then take it out for use;

[0040] S2, weigh 0.9g palladium chloride, add 2mL hydrochloric acid to prepare chloropalladium acid solution;

[0041] S3, weigh 0.06g of the prepared chloropalladic acid solution and dissolve it in 2.7mL of deionized water, then evenly add the solution dropwise onto 3g of pretreated activated carbon, ultrasonically treat for 15min, let stand for 24h, and then put it in a 120℃ oven to dry for 12h;

[0042] S4. Reduce the catalyst under hydrogen atmosphere for 2 h, the reduction temperature is 250° C., and the hydrogen flow rate is 15 mL / min to obtain a Pd / C catalyst, named Pd / C-HCl.

[0043] Example 3

[0044] The preparation of Pd-K / C catalyst (carrier C is pretreated with HCl) specifically comprises the following steps:

[0045] S1. Take 30g of activated carbon and place it in a 500mL round-bottom flask. Stir the activated carbon in a 37% hydrochloric acid solution with magnetic stirring for 6h. The stirring temperature is 80℃ and the speed is 500r / min. Then wash it with 100℃ deionized water until it is neutral, put it in a 120℃ oven to dry for 12h and then take it out for use;

[0046] S2, weigh 0.9g palladium chloride, add 2mL hydrochloric acid to prepare chloropalladium acid solution;

[0047] S3, weigh 0.06g of the prepared chloropalladic acid solution and 0.03g of potassium chloride solution, and dissolve them in 2.7mL of deionized water, then evenly add the solution dropwise onto 3g of pretreated activated carbon, ultrasonically treat for 15min, let stand for 24h, and then put it in a 120℃ oven to dry for 12h;

[0048] S4. Reduce the catalyst under hydrogen atmosphere for 2 h, the reduction temperature is 250° C., and the hydrogen flow rate is 15 mL / min to obtain a Pd / C catalyst named Pd-K / C-HCl.

[0049] Example 4

[0050] The preparation of Pd-Mg / C catalyst (carrier C is pretreated with HCl) specifically comprises the following steps:

[0051] S1. Take 30g of activated carbon and place it in a 500mL round-bottom flask. Stir the activated carbon in a 37% hydrochloric acid solution with magnetic stirring for 6h. The stirring temperature is 80℃ and the speed is 500r / min. Then wash it with 100℃ deionized water until it is neutral, put it in a 120℃ oven to dry for 12h and then take it out for use;

[0052] S2, weigh 0.9g palladium chloride, add 2mL hydrochloric acid to prepare chloropalladium acid solution;

[0053] S3, weigh 0.06g of the prepared chloropalladic acid solution and 0.03g of magnesium chloride solution, and dissolve them in 2.7mL of deionized water, then evenly add the solution dropwise to 3g of pretreated activated carbon, ultrasonically treat for 15min, let stand for 24h, and then put it in a 120℃ oven to dry for 12h;

[0054] S4. Reduce the catalyst under hydrogen atmosphere for 2 h, the reduction temperature is 250° C., and the hydrogen flow rate is 15 mL / min to obtain a Pd / C catalyst named Pd-Mg / C-HCl.

[0055] Example 5

[0056] The preparation of Pd-Ba / C catalyst (carrier C is pretreated with HCl) specifically comprises the following steps:

[0057] S1. Take 30g of activated carbon and place it in a 500mL round-bottom flask. Stir the activated carbon in a 37% hydrochloric acid solution with magnetic stirring for 6h. The stirring temperature is 80℃ and the speed is 500r / min. Then wash it with 100℃ deionized water until it is neutral, put it in a 120℃ oven to dry for 12h and then take it out for use;

[0058] S2, weigh 0.9g palladium chloride, add 2mL hydrochloric acid to prepare chloropalladium acid solution;

[0059] S3, weigh 0.06g of the prepared chloropalladic acid solution and 0.03g of barium nitrate solution, and dissolve them in 2.7mL of deionized water, then evenly add the solution dropwise onto 3g of pretreated activated carbon, ultrasonically treat for 15min, let stand for 24h, and then put it in a 120℃ oven to dry for 12h;

[0060] S4. Reduce the catalyst under hydrogen atmosphere for 2 h, the reduction temperature is 250° C., and the hydrogen flow rate is 15 mL / min to obtain a Pd / C catalyst named Pd-Ba / C-HCl.

[0061] Experimental Example 1

[0062] The catalytic hydrodechlorination reaction of different types of waste chlorofluorocarbons is carried out in a fixed bed reactor. The reaction tube is a nickel-chromium-iron alloy reaction tube with an inner diameter of 18 mm and an isothermal zone length of 150 mm. Each time, 1 g of catalyst is loaded into the isothermal zone. The reaction temperature is 300 ° C, the reaction pressure is atmospheric pressure, and the space velocity of the raw material mixed gas is 150 h -1 , where H 2 The ratio of the feed volume flow rate to that of chlorofluorocarbons was 3: 1. The reaction products were analyzed by gas chromatography to calculate the conversion of the reactants and the selectivity of the target products.

[0063] According to the above operation process, the performance of the catalysts of Examples 1-5 was evaluated respectively, and the specific reaction temperature, reaction space velocity, conversion rate of the reactants and selectivity of the corresponding target products are summarized in Table 1;

[0064] Table 1. Catalyst application conversion and selectivity results

[0065]

[0066] In Experiment 1, when evaluating the performance of the catalyst, three groups of hydrodechlorination reactions of chlorofluorocarbons were carried out, namely: the hydrodechlorination reaction of CFC-114 to produce HFC-134a, the hydrodechlorination reaction of HCFC-21 to produce HFC-41, and the hydrodechlorination reaction of a mixture of the two chlorofluorocarbons to produce HFC-134a and HFC-41;

[0067] The results in Table 1 show that the Pd-M / C catalysts (catalysts of Examples 3, 4, and 5) obtained by the present invention are used for hydrodechlorination reactions of different types of chlorofluorocarbons under mild reaction conditions and exhibit high catalytic activity and main product selectivity, wherein the conversion rates of C2 chlorofluorocarbons are all higher than 95%, with a maximum of 98%, and the selectivity of the corresponding target products are all higher than 80%, with a maximum of 85%, the conversion rates of C1 chlorofluorocarbons are all higher than 75%, with a maximum of 80%, and the selectivity of the corresponding target products are all higher than 70%, with a maximum of 75%, the conversion rates of C1+C2 mixed chlorofluorocarbons are all higher than 65%, with a maximum of 76%, and the selectivity of the corresponding target products are all higher than 55%, with a maximum of 69%, and the catalysts have the characteristics of high activity and high selectivity compared to the Pd / C of Example 1 and the Pd / C-HCl of Example 2;

[0068] like Figures 1 to 4 As shown, the catalysts prepared in Examples 1-5 of the present invention are named catalysts 1-5, respectively. Catalyst 2, catalyst 3, catalyst 4 and catalyst 5 are characterized by TEM, respectively. The black dots in the TEM images are the active component Pd loaded on the carrier. It can be seen that compared with catalyst 2, the particle size of Pd loaded on the carrier of catalyst 3, catalyst 4 and catalyst 5 is smaller, indicating that the addition of the additive M reduces the particle size of the catalyst, exposes more active sites, and thus improves the catalyst performance.

[0069] Experimental Example 2

[0070] The catalytic hydrodechlorination reaction of HCFC-21 was carried out in a single-tube fixed-bed reactor with a reactor height of 800 mm and an inner diameter of 40 mm. Each time, 100 g of catalyst was loaded in the isothermal zone, the reaction temperature was 300 ° C, the reaction pressure was atmospheric pressure, and the space velocity of the raw material mixed gas was 500 h -1 ; where H 2 The ratio of the feed volume flow rate to HCFC-21 is 3: 1. The reaction products are analyzed by gas chromatography to calculate the conversion of the reactants and the selectivity of the target product;

[0071] According to the above operation process, the catalytic stability performance of the catalysts of Examples 1, 2, 3, 4, and 5 was evaluated respectively, and the reaction results are summarized in Table 2 (* indicates not evaluated).

[0072] Table 2. Catalyst reaction stability test results

[0073]

[0074] The results in Table 2 show that when the catalysts of Examples 3, 4 and 5 are used for the catalytic hydrodechlorination of dichlorofluoromethane (HCFC-21) to prepare fluoromethane (HFC-41), the reaction conditions are mild, and after 1000 hours of reaction, the catalysts still maintain a relatively high catalytic performance, and are suitable for industrial production. For example, when the catalyst of Example 4 is used continuously for 1000 hours, the conversion rate of HCFC-21 still remains at 76%, and the catalyst has a very high catalytic stability. When the catalysts of Examples 3, 4 and 5 are used for the hydrodechlorination reaction of C1 fluorochlorocarbon HCFC-21, the resource utilization rate remains above 50%.

[0075] Experimental Example 3

[0076] The catalytic hydrodechlorination reaction of CFC-114 was carried out in a single-tube fixed-bed reactor with a reactor height of 800 mm and an inner diameter of 40 mm. Each time, 100 g of catalyst was loaded in the isothermal zone, the reaction temperature was 300 ° C, the reaction pressure was atmospheric pressure, and the space velocity of the raw material mixed gas was 500 h -1 ; where H 2 The ratio of the feed volume flow rate to CFC-114 is 3: 1. The reaction products are analyzed by gas chromatography to calculate the conversion of the reactants and the selectivity of the target product.

[0077] According to the above operation process, the catalytic stability performance of the catalysts of Examples 1, 2, 3, 4, and 5 was evaluated respectively, and the reaction results are summarized in Table 3 (* indicates not evaluated).

[0078] Table 3. Catalyst reaction stability test results

[0079]

[0080] The results in Table 3 show that when the catalysts of Examples 3, 4 and 5 are used for the catalytic hydrodechlorination of tetrafluorodichloroethane (CFC-114) to prepare tetrafluoroethane (HFC-134a), the reaction conditions are mild, and after 1000 hours of reaction, the catalysts still maintain high catalytic performance, and are suitable for industrial production. For example, when the catalyst of Example 4 is used continuously for 1000 hours, the conversion rate of CFC-114 still remains at 89%, and it has high catalytic stability. And when the catalysts of Examples 3, 4 and 5 are used for the hydrodechlorination reaction of C2 fluorochlorocarbon CFC-114, the resource utilization rate remains above 70%.

[0081] Experimental Example 4

[0082] The catalytic hydrodechlorination reaction of HCFC-21 and CFC-114 mixed chlorofluorocarbons was carried out in a single tube fixed bed reactor with a reactor height of 800 mm and an inner diameter of 40 mm. Each time, 100 g of catalyst was loaded in the isothermal zone, the reaction temperature was 300 ° C, the reaction pressure was atmospheric pressure, and the space velocity of the raw material mixed gas was 500 h -1 ; where H 2 The ratio of the feed volume flow rate to the mixed chlorofluorocarbons was 5: 1. The reaction products were analyzed by gas chromatography to calculate the conversion of the reactants and the selectivity of the target product.

[0083] According to the above operation process, the catalytic stability performance of the catalysts of Examples 1, 2, 3, 4, and 5 was evaluated respectively, and the reaction results are summarized in Table 4 (* indicates not evaluated).

[0084] Table 4. Catalyst reaction stability test results

[0085]

[0086] The results in Table 4 show that when the catalysts of Examples 3, 4 and 5 are used for the catalytic hydrodechlorination of mixed fluorochlorocarbon tetrafluorodichloroethane (CFC-114) and dichlorofluoromethane (HCFC-21) to prepare tetrafluoroethane (HFC-134a) and fluoromethane (HFC-41), the reaction conditions are mild, and after 1000 hours of reaction, the catalyst still maintains a relatively high catalytic performance, and is suitable for industrial production. For example, when the catalyst of Example 4 is used continuously for 1000 hours, the conversion rates of CFC-114 and HCFC-21 are still maintained at 70% and 61%, respectively, and the catalyst has a very high catalytic stability. Moreover, when the catalysts of Examples 3, 4 and 5 are used for the hydrodechlorination reaction of C1+C2 mixed fluorochlorocarbons CFC-114+HCFC-21, the resource utilization rate is still maintained at more than 73%.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A preparation method of a Pd-M / C catalyst, characterized in that: It comprises a main active component, an auxiliary element M and a carrier C, wherein the main active component is a precious metal Pd, the auxiliary element M is at least one of K, Mg and Ba, and the carrier C is at least one of activated carbon and carbon black; The preparation steps include: S1. Pre-treating the carrier C: firstly subjecting the carrier C to an acid treatment, then washing it to neutrality and drying it for later use; S2, preparing a catalyst intermediate: after ultrasonic treatment, dropwise adding a soluble palladium salt solution onto the pretreated carrier of S1 for impregnation, and drying to obtain a catalyst intermediate; S3, preparing a catalyst precursor: adding the additive M precursor dropwise to the catalyst intermediate of S2 for impregnation; S4, reduction: reduce the catalyst in S3 under a reducing atmosphere for 2-4 hours to obtain a supported hydrodechlorination catalyst Pd-M / C.

2. The preparation of a Pd-M / C catalyst according to claim 1, characterized in that: The specific operation steps of pre-treating the carrier C in S1 are as follows: S1-1, placing carrier C in a hydrochloric acid solution with a volume concentration of 10-40% and a solid-liquid ratio of 1:10-15, stirring and refluxing at 60-100° C. for 3-9 hours; S1-2. Wash the carrier C treated with hydrochloric acid with distilled water until it becomes neutral, and dry it at 70-130° C. for 6-14 hours.

3. The preparation of a Pd-M / C catalyst according to claim 1, characterized in that: The mass concentration of the soluble palladium salt solution in S2 is 1-6%, and it is palladium chloride, palladium nitrate or palladium acetate. The ultrasonic time of the soluble palladium salt solution is 5-15 minutes, the immersion time is 12-28 hours, the drying temperature is 80-120° C., and the drying time is 6-14 hours.

4. The preparation of a Pd-M / C catalyst according to claim 1, characterized in that: The M precursor of the S3 process is at least one of potassium chloride, magnesium chloride and barium nitrate, the immersion time is 12-28 hours, the drying temperature is 80-120° C., and the drying time is 6-14 hours.

5. The preparation of a Pd-M / C catalyst according to claim 1, characterized in that: The reducing atmosphere in S4 is hydrogen, the reducing temperature is 200-400° C., and the reducing gas flow rate is 15-30 ml / min.

6. An application of a Pd-M / C catalyst, characterized in that: It is used in the hydrodechlorination reactions of different types of waste chlorofluorocarbons.

7. The use of a Pd-M / C catalyst as claimed in claim 6, characterized in that: The catalytic reaction is carried out in a fixed bed reaction device. The catalyst is loaded in the fixed bed reaction device, and after the temperature is raised to the reaction temperature, H2 is introduced to react with the raw material mixed gas of the waste chlorofluorocarbon. The reaction temperature is 200-500°C, the reaction pressure is normal pressure, and the space velocity of the raw material mixed gas is 100-1000h -1 .

8. The use of a Pd-M / C catalyst as claimed in claim 7, characterized in that: The ratio of the feed volume flow rate of H2 to chlorofluorocarbon is 1-4:

1.

9. The use of a Pd-M / C catalyst as claimed in claim 8, characterized in that: The waste chlorofluorocarbons are single C1 type chlorofluorocarbons, C2 type chlorofluorocarbons and mixed chlorofluorocarbons.

10. The use of a Pd-M / C catalyst as claimed in claim 9, characterized in that: The C1 type fluorochlorocarbon is dichlorofluoromethane, the C2 type fluorochlorocarbon is tetrafluoroethylene dichloroethane, and the mixed fluorochlorocarbon is dichlorofluoromethane + tetrafluoroethylene dichloroethane.

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