JP2580696B2 - Method for producing pentafluoroethane - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing pentafluoroethane, which is a kind of fluorocarbon containing no chlorine.

[Related Art and Problems of the Invention] In recent years, the possibility of destruction of the ozone layer by chlorofluorocarbon (fluorocarbon) widely used as a refrigerant, a blowing agent, and a solvent has been discussed, and the production and use thereof have been regulated. is there. The correlation between the current change in the concentration of the ozone layer and CFCs is not always clear, but it is believed that chlorine compounds generated by decomposition of CFCs by ultraviolet light act as catalysts for the ozone decomposition reaction. . It is considered that an alternative fluorocarbon containing hydrogen and having a structure decomposing in the atmosphere is suitable.

[Means for Solving the Problems] Pentafluoroethane (CHF ₂ CF ₃ : R-125) is an ethane derivative having no fluorine in its molecule and five atoms of fluorine, and is nonflammable. It has a boiling point of -48.5 ° C and has the potential to be used as a refrigerant. There is also a use as a heat medium for a heat pump. However, there is currently no commercial mass production.

Among various production methods that can be used for producing pentafluoroethane, a reaction using chloropentafluoroethane (boiling point: −39.1 ° C.) as a raw material, which is commercially produced, is carried out by hydrogen reduction in the gas phase. (See the formula below), Suitable for industrial production. Therefore, as a result of intensive studies on optimization of the reaction conditions, it was confirmed that good reaction results were obtained in a gas phase reaction and a liquid phase reaction, and the present invention was provided.

 Hereinafter, the details will be described.

In this reduction reaction, chlorine in the chloropentafluorotan molecule is extracted and replaced with hydrogen. As a catalyst for this, a known hydrogenation catalyst, that is, one of a platinum group element, an iron group element, or rhenium, or 2
Among the catalysts containing at least one species as a main component, those having acid resistance are applicable. Among the platinum group, especially palladium,
Platinum, rhodium, ruthenium and the like are preferred. Among the iron group, nickel and cobalt are preferable, and the initial characteristics and durability can be improved by combining with the platinum group element. The characteristics of rhenium can be similarly improved by combining it with a platinum group element.

In the present invention, as the carrier of the reduction catalyst, for example,
Alumina, activated carbon and the like are preferred. The amount of catalyst supported is 0.01 to
10% by weight, preferably 0.1-5% by weight, properties, cost,
It is suitable from the point of, etc.

In use, the metal compound is at least partially reduced.

The ratio of hydrogen to raw material R-115 can vary widely. However, usually chlorine is replaced by hydrogen using stoichiometric amounts of hydrogen. Substantially higher stoichiometric amounts, for example 4 moles or more, of hydrogen can be used relative to the total number of moles of raw material R-115. The reaction pressure may be normal pressure or a pressure higher than normal pressure.

The reaction temperature is 0 ° C. to 450 ° C., preferably 50 ° C. to 300 ° C., and the reaction is suitably performed in a liquid phase or a gas phase.

The contact time is usually 0.1 to 3 when the reaction is carried out in the gas phase.
00 seconds, especially 5 to 100 seconds.

The liquid phase reaction needs to be performed in a pressurized state due to the physical properties of the raw material and the product.

[Example] An example of the present invention will be described below.

Preparation Example Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH with chlorine, an aqueous solution in which palladium chloride was dissolved by 0.5% by weight based on the total weight of the metal component with respect to the weight of the activated carbon was added dropwise little by little, and the ionic component was adsorbed on the activated carbon. After washing with pure water, it is
Dried for hours. Next, after drying in nitrogen at 550 ° C for 4 hours,
Hydrogen was introduced and reduced at 300 ° C. for 5 hours.

Example 1 300 cc of palladium catalyst prepared as in Preparation Example
The filled Inconel 600 reaction tube having an inner diameter of 2.6 cm and a length of 100 cm was immersed in a salt bath furnace.

Hydrogen and chloropentafluoroethane were introduced into the reaction tube at a molar ratio of 2: 1. The flow rates of hydrogen and starting material are respectively
100 cc / min and 100 cc / min. The reaction temperature was 300 ° C., and the contact time was 20 seconds. Gas chromatography was used for the analysis of the produced gas. Table 1 shows the results.

Example 2 A catalyst was prepared and reacted in the same manner as in Example 1 except that the loading amount was 5% by weight. Table 1 shows the results.

Example 3 Activated carbon was immersed in pure water to impregnate the water into the pores. After adjusting the pH using hydrochloric acid, an aqueous solution in which palladium chloride was dissolved by 0.5% by weight based on the total weight of the metal component with respect to the weight of the activated carbon was added dropwise little by little, and the ionic component was adsorbed on the activated carbon. An aqueous solution of sodium borohydride was added dropwise while stirring this solution to effect reduction. After washing with pure water, it was dried at 150 ° C. for 5 hours. Then 550 in nitrogen
After drying at 4 ° C. for 4 hours, hydrogen was introduced and kept at 300 ° C. for 5 hours.

A reaction was carried out in the same manner as in Example 1 using the catalyst thus prepared. Table 1 shows the results.

Example 4 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH with hydrochloric acid, an aqueous solution in which palladium chloride and chloroplatinic acid were each dissolved in an amount of 0.25% by weight of the total weight of the metal components with respect to the weight of the activated carbon was added dropwise little by little, and the ionic components were adsorbed on the activated carbon. . After washing with pure water, it was dried at 150 ° C. for 5 hours. Then in nitrogen 5
After drying at 50 ° C. for 4 hours, hydrogen was introduced, reduced at 300 ° C. for 5 hours, and then heated to 500 ° C. and maintained for 3 hours.

Using the catalyst thus prepared, a reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

Example 5 A catalyst was prepared and reacted in the same manner as in Example 4 except that rhodium chloride was used instead of chloroplatinic acid. Table 1 shows the results.

Example 6 A catalyst was prepared and reacted in the same manner as in Example 4 except that ruthenium chloride was used instead of chloroplatinic acid. Table 1 shows the results.

Example 7 Activated carbon was immersed in pure water to impregnate water into the pores. After adjusting the pH with hydrochloric acid, an aqueous solution in which palladium chloride and potassium perrhenate are dissolved by 0.4% by weight and 0.1% by weight, respectively, based on the total weight of the activated carbon based on the weight of the activated carbon is added dropwise little by little to remove the ionic components. Adsorbed on activated carbon. After washing with pure water, it was dried at 150 ° C. for 5 hours. Next, after drying in nitrogen at 550 ° C. for 4 hours, hydrogen was introduced, reduced at 300 ° C. for 5 hours, and then heated to 500 ° C. and maintained for 3 hours.

The reaction was carried out using the catalyst thus prepared. Table 1 shows the results.

Example 8 A catalyst was prepared and reacted in the same manner as in Example 4 except that nickel chloride was used instead of chloroplatinic acid. Table 1 shows the results.

Example 9 A catalyst was prepared and reacted in the same manner as in Example 4 except that cobalt chloride was used instead of chloroplatinic acid. The results are shown in Table 1.

Example 10 A reaction was carried out in the same manner as in Example 1 using a catalyst prepared in the same manner as in Preparation Example except that chloroplatinic acid was used instead of palladium chloride. Table 1 shows the results.

Example 11 A reaction was carried out in the same manner as in Example 1 using a catalyst prepared in the same manner as in Preparation Example except that rhodium chloride was used instead of palladium chloride. Table 1 shows the results.

Example 12 A reaction was carried out in the same manner as in Example 1 using a catalyst prepared in the same manner as in Preparation Example except that ruthenium chloride was used instead of palladium chloride. Table 1 shows the results.

Example 13 A catalyst was prepared and reacted in the same manner as in Example 7 except that rhodium chloride was used instead of palladium chloride. Table 1 shows the results.

Example 14 A catalyst was prepared and reacted in the same manner as in Example 7 except that chloroplatinic acid was used instead of palladium chloride. Table 1 shows the results.

Example 15 A catalyst was prepared and reacted in the same manner as in Example 7 except that ruthenium chloride was used instead of palladium chloride.
Table 1 shows the results.

Example 16 200 g of chloropentafluoroethane, 250 g of triethylamine, and 28 g of the palladium catalyst used in Example 2 were placed in an autoclave made of Hastelloy C having an internal volume of 1 liter.
And kept at 0 ° C. While stirring, introduce hydrogen so that the internal pressure is maintained at 10 atm.
Hold for 10 hours. The gas composition was analyzed by gas chromatography. Table 1 shows the results. The percentages in Table 1 all represent mol%.

[Effect of the Invention] As shown in the Examples, the present invention produces pentafluoroethane (R-125), which is useful using chloropentafluoroethane (R-115) as a raw material, smoothly and advantageously in good yield. It has the effect of obtaining.

Continued on the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location B01J 23/46 311 B01J 23/46 311X 23/656 23/89 X 23/89 C07B 61/00 300 C07B 61 / 00 300 B01J 23/64 104X (56) References JP-A-64-38034 (JP, A) JP-A-53-147005 (JP, A) JP-A-1-14939 (JP, A) JP-A-1- 128942 (JP, A) JP-A-1-172349 (JP, A)

Claims (4)

(57) [Claims] 1. A method of reducing chloropentafluoroethane with hydrogen in the presence of a hydrogenation catalyst containing one or more elements selected from platinum group elements, iron group elements and rhenium as main components. Pentafluoroethane production method. 2. The process according to claim 1, wherein at least a stoichiometric amount of hydrogen is used relative to chloropentafluoroethane. 3. The production method according to claim 1, wherein the carrier of the hydrogenation catalyst is activated carbon or alumina. 4. The reaction is carried out at 0 ° C. in a liquid phase or a gas phase.
The method according to claim 1, 2 or 3, wherein the method is carried out in a temperature range of -450 ° C.