A method for the coproduction of pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane

Abstract

The invention relates to a method for co-producing pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane, wherein dichloromonofluoromethane is used as a raw material, high-temperature pyrolysis isperformed to obtain CClF=CClF, and the CClF=CClF and HF are subjected to gas phase addition and fluorination to obtain pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane. According to the present invention, the method has characteristics of novel preparation route, less by-product and low cost, can achieve the co-production of pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane, and canfurther achieve the conversion utilization of dichloromonofluoromethane.

Description

technical field

[0001] The invention relates to the technical field of fluorine chemical industry, in particular to a method for jointly producing pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane. Background technique

[0002] Pentafluoroethane (HFC-125, CF 3 CHF 2 ), boiling point -48°C, freezing point -103°C, ODP value 0, GWP value is low, is a kind of fluorinated hydrocarbon compound that does not damage the atmospheric ozone layer, is widely used as foaming agent, solvent and fire extinguishing agent, especially It has been successfully applied and promoted in the preparation of mixed refrigerants.

[0003] For the preparation method of pentafluoroethane, prior art reports basically use tetrachloroethylene, tetrafluoroethylene, trichloroethylene and 1,1,1-trichloro-2,2-dichloroethane as raw materials to prepare pentafluoroethane. Fluoroethanes, such as:

[0004] (1) U.S. Patent No. 6,025,532 reports a two-step method for preparing pentafluoroethane using tetr...

Examples

preparation example Construction

[0035] The preparation mechanism of the present invention is as follows: in step 1, fluorodichloromethane undergoes a gas phase cracking reaction to obtain CClF=CClF. In step (2), CClF=CClF and hydrogen fluoride gas undergo gas phase addition and fluorination reaction to obtain pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane, and the reaction pressure comes from autogenous pressure , It is advisable to control the reaction time at 0.5-5h.

[0036]It can be seen from the above description that the beneficial effect of the present invention is that: a kind of fluorodichloromethane is provided as a raw material for co-production of pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane The method has the characteristics of novel preparation route, few by-products and low cost, and can not only realize the joint production of pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane, but also realize a Conversion and utilization of fluorodichloromethane.

[0037] Furth...

Embodiment 1

[0048] Embodiment 1: Cracking of a fluorodichloromethane

[0049] CClF=CClF is prepared by cleavage of fluorodichloromethane. The reaction tube adopts a Ni tube with an inner diameter of 12 mm and a length of 50 cm, and is placed in a tube furnace to heat up. In the present invention, in order to prevent the material from condensing, all reaction connecting pipelines are made of stainless steel tubes, and the temperature is kept at about 70 ° C with a heat-insulating heating jacket. Fluorodichloromethane uses a mass flow meter to control the flow rate (100mL / min). The reaction temperature was kept stable at 700° C., and the reaction pressure was normal pressure. Before the reaction, fluorodichloromethane is preheated at 100-150°C and mixed with water vapor into the nickel tube reactor for reaction, and the contact time is 5s. The tail gas generated by the reaction is quenched, washed with alkali, washed with water, dried, compressed, rectified and purified to obtain chlorotr...

Embodiment 2

[0050] Example 2: Cracking of fluorodichloromethane

[0051] Repeat the process of Example 1, and the reaction tube is filled with acid-washed gac. Before the reaction, the coconut shell activated carbon was crushed, and 20 mL of granules with a mesh size of 10-20 mesh (0.8-1.4mm) were screened and loaded into the reactor, at 200°C N 2 Dry in situ for 2 hours, activate in situ with anhydrous HF for 2.5 hours at 250°C, then switch to fluorodichloromethane material, control the flow rate of fluorodichloromethane to 60mL / min, the reaction temperature to 600°C, and the residence time 4s. Activated carbon was treated with 20% HNO before loading into the reactor 3 Reflux in a water bath at 90°C for 5h, wash with deionized water until neutral, and dry at 110°C for 10h. The yield of CClF=CClF generated by the reaction is above 81%.

technical field

[0001] The invention relates to the technical field of fluorine chemical industry, in particular to a method for jointly producing pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane. Background technique

[0002] Pentafluoroethane (HFC-125, CF 3 CHF 2 ), boiling point -48°C, freezing point -103°C, ODP value 0, GWP value is low, is a kind of fluorinated hydrocarbon compound that does not damage the atmospheric ozone layer, is widely used as foaming agent, solvent and fire extinguishing agent, especially It has been successfully applied and promoted in the preparation of mixed refrigerants.

[0003] For the preparation method of pentafluoroethane, prior art reports basically use tetrachloroethylene, tetrafluoroethylene, trichloroethylene and 1,1,1-trichloro-2,2-dichloroethane as raw materials to prepare pentafluoroethane. Fluoroethanes, such as:

[0004] (1) U.S. Patent No. 6,025,532 reports a two-step method for preparing pentafluoroethane using tetr...

Examples

preparation example Construction

[0035] The preparation mechanism of the present invention is as follows: in step 1, fluorodichloromethane undergoes a gas phase cracking reaction to obtain CClF=CClF. In step (2), CClF=CClF and hydrogen fluoride gas undergo gas phase addition and fluorination reaction to obtain pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane, and the reaction pressure comes from autogenous pressure , It is advisable to control the reaction time at 0.5-5h.

[0036]It can be seen from the above description that the beneficial effect of the present invention is that: a kind of fluorodichloromethane is provided as a raw material for co-production of pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane The method has the characteristics of novel preparation route, few by-products and low cost, and can not only realize the joint production of pentafluoroethane and 1,2-dichloro-1,1,2-trifluoroethane, but also realize a Conversion and utilization of fluorodichloromethane.

[0037] Furth...

Embodiment 1

[0048] Embodiment 1: Cracking of a fluorodichloromethane

[0049] CClF=CClF is prepared by cleavage of fluorodichloromethane. The reaction tube adopts a Ni tube with an inner diameter of 12 mm and a length of 50 cm, and is placed in a tube furnace to heat up. In the present invention, in order to prevent the material from condensing, all reaction connecting pipelines are made of stainless steel tubes, and the temperature is kept at about 70 ° C with a heat-insulating heating jacket. Fluorodichloromethane uses a mass flow meter to control the flow rate (100mL / min). The reaction temperature was kept stable at 700° C., and the reaction pressure was normal pressure. Before the reaction, fluorodichloromethane is preheated at 100-150°C and mixed with water vapor into the nickel tube reactor for reaction, and the contact time is 5s. The tail gas generated by the reaction is quenched, washed with alkali, washed with water, dried, compressed, rectified and purified to obtain chlorotr...

Embodiment 2

[0050] Example 2: Cracking of fluorodichloromethane

[0051] Repeat the process of Example 1, and the reaction tube is filled with acid-washed gac. Before the reaction, the coconut shell activated carbon was crushed, and 20 mL of granules with a mesh size of 10-20 mesh (0.8-1.4mm) were screened and loaded into the reactor, at 200°C N 2 Dry in situ for 2 hours, activate in situ with anhydrous HF for 2.5 hours at 250°C, then switch to fluorodichloromethane material, control the flow rate of fluorodichloromethane to 60mL / min, the reaction temperature to 600°C, and the residence time 4s. Activated carbon was treated with 20% HNO before loading into the reactor 3 Reflux in a water bath at 90°C for 5h, wash with deionized water until neutral, and dry at 110°C for 10h. The yield of CClF=CClF generated by the reaction is above 81%.