JPH01258632A - Production of pentafluoroethane - Google Patents

Abstract

PURPOSE:To obtain the present substance in good yield, by reducing chloropentafluoroethane with hydrogen in the presence of a platinum group, iron family element, rhenium, etc., as a principal component supported on active carbon or alumina. CONSTITUTION:Chloropentafluoroethane is reduced with hydrogen in at least a stoichiometric amount in the presence of a hydrogenation catalyst consisting essentially of one or two or more selected from platinum group, iron family elements and rhenium in the liquid or vapor phase at 0-450 deg.C (preferably 50-300 deg.C) to afford the present substance. Pd, Pt, Rh, Ru, etc., are preferred as the platinum group elements in the catalyst components and initial characteristics and durability can be improved by combination thereof with the iron family elements (preferably Ni or Co) and rhenium. The present substance finds uses as a refrigerant, heating medium, etc., for heat pumps.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing pentafluoroethane, which is a type of fluorocarbon that does not contain chlorine.

Prior Art and Problems with the Invention] In recent years, the possibility of depletion of the ozone layer by chlorofluorocarbons (fluorocarbons), which are widely used as refrigerants, blowing agents, and solvents, has been discussed, and there is a trend towards regulating their production and use. be. Although the correlation between current changes in the concentration of the ozone layer and CFCs is not necessarily clear, it is thought that chlorine compounds produced when CFCs are decomposed by ultraviolet light act as catalysts for the ozone decomposition reaction. . For this purpose, it is thought that suitable CFC substitutes are those that contain hydrogen and have a structure that decomposes in the atmosphere.

[Means for solving the problem] Pentafluoroethane (CHF2CF3: R125
> is an ethane derivative that does not contain chlorine in its molecule and has five fluorine atoms, and is nonflammable. The boiling point is -48□5
"C" and has the possibility of being used as a refrigerant. Also,
It is also used as a heating medium for heat pumps. However, commercial mass production is not currently underway.

Among various possible methods for producing pentafluoroethane, the reaction using commercially produced chloropentafluoroethane (boiling point: 39.1°C) as a raw material is a gas phase reaction. It is possible to perform hydrogen reduction (see the formula below), CHF2CF3 → CH
F2CF3 + t(CI(R-115) reduction catalyst (R-125) Suitable for industrial production.
Therefore, as a result of intensive studies on optimizing the reaction conditions, it was confirmed that good reaction results could be obtained in gas phase reactions and liquid phase reactions, and the present invention was provided.

The details will be explained below.

In this reduction reaction, chlorine in the chloropentafluoroethane molecule is extracted and replaced with hydrogen.

As a catalyst for this purpose, among the known hydrogenation catalysts, that is, catalysts containing as a main component any one or more of platinum group elements, iron group elements, or rhenium, those having acid resistance are used. Applicable. Among the platinum group metals, palladium, platinum, rhodium, ruthenium, etc. are particularly preferred. Among the iron group elements, nickel and cobalt are preferred, and by combining them with platinum group elements, initial characteristics and durability can be improved. Similarly, the characteristics of rhenium can be improved by combining it with a platinum group element.

In the present invention, suitable carriers for the reduction catalyst include, for example, alumina and activated carbon. The amount of catalyst supported is 0.01
~10%, preferably 0.1~5% is suitable from the viewpoint of characteristics, cost, etc.

In addition, upon use, such metal compounds are at least partially reduced.

The proportions of hydrogen and feedstock R-115 can vary widely. However, stoichiometric amounts of hydrogen are usually used to remove the halogen atoms. A more than stoichiometric amount of hydrogen may be used, for example 4 moles or more, based on the total number of moles of raw material R-115. As for the reaction pressure, normal pressure or a pressure higher than normal pressure can be used.

The reaction temperature is 0°C to 450°C, preferably 50'C to 30°C.
It is appropriate to conduct the reaction at 0° C. in a liquid phase or a gas phase.

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

The liquid phase reaction must be carried out under pressure due to the physical properties of the raw materials and products.

[Example] Example 3 of the present invention is shown below.

Preparation example Activated carbon was immersed in pure water to impregnate the inside of the pores with water.

After adjusting the pH using hydrochloric acid, an aqueous solution containing palladium chloride dissolved in an amount of 0.5% of the total weight of the metal component in the active carbon was added dropwise little by little to allow the ionic components to be adsorbed onto the 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 and the mixture was maintained at 300′CG for 5 hours to reduce.

Example 1 A palladium catalyst prepared as in Preparation Example was
A reaction tube made of Inconel 600 and having an inner diameter of 2.6 cm and a length of 1100 C was immersed in a salt bath furnace.

Hydrogen and chloropentafluoroethane were introduced into the reaction tube in a molar ratio of 2=1. The flow rates of hydrogen and starting storage are as follows:
100cc/min, 0 reaction temperature at 100cc/min is 3
00°C5 contact time was 20 seconds. Gas chromatography was used to analyze the generated gas.

The results are shown in Table 1.

Example 2 A catalyst was prepared in the same manner as in Example except that the supported amount was changed to 5%). 2 reactions were carried out. The results are shown in Section 1.2.

Example 3 Activated carbon was immersed in pure water to impregnate the inside of the a1 hole with 71 liters. pH using hydrochloric acid? 'After adjusting 17, the total weight of metal components is 0 with respect to the weight of palladium chloride 3 activated carbon,
An aqueous solution in which only 5% of the ionic components were dissolved was dropped little by little, and the ionic components were adsorbed onto the activated carbon. While stirring this solution, an aqueous solution of sulfur and lithium borohydride was added dropwise to perform reduction. After washing with pure water, it was dried at 150°C for 5 hours, then dried in nitrogen at 550°C for 4 hours, then 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. The results are shown in Table 1.

Example 4 The activated carbon was immersed in pure water to impregnate the inside of the pores with water.

After adjusting p ) ( using hydrochloric acid, palladium chloride,
Then, an aqueous solution in which 0.25% of the total weight of metal components was dissolved in each of the activated carbon and chloroplatinic acid was added dropwise little by little to cause the ionic components to be adsorbed onto the 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,
After being reduced by holding at 300'C for 5 hours, the temperature was raised to 500°C and held for 3 hours.

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

Example 5 A catalyst was prepared and a reaction was carried out in the same manner as in Example 4, except that rhodium chloride was used instead of chloroplatinic acid. The results are shown in Table 1.

Example 6 A catalyst was prepared and a reaction was carried out in the same manner as in Example 4, except that ruthenium chloride was used instead of chloroplatinic acid. The results are shown in Table 1.

Example 7 Activated carbon was immersed in pure water to impregnate the inside of the pores with water.

After adjusting the pH using hydrochloric acid, an aqueous solution in which palladium chloride and potassium peroxide were dissolved at 0.4% and 0.1%, respectively, based on the total weight of the metal components based on the weight of activated carbon, was added dropwise little by little. The ionic components were adsorbed onto 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, and the temperature was maintained at 300°C for 5 hours for reduction, and then the temperature was raised to 500°C and maintained for 3 hours.

A reaction was carried out using the catalyst thus prepared.

The results are shown in Table 1.

Example 8 A catalyst was prepared and a reaction was carried out in the same manner as in Example 4, except that nickel chloride was used instead of chloroplatinic acid. The results are shown in Table 1.

Example 9 A catalyst was prepared and a reaction was carried out 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. The results are shown in Table 1.

Example 11 A reaction was carried out in the same manner as in Example 1 using the catalysts prepared in Preparation Examples 1 and 7, except that rhodium chloride was used instead of palladium chloride. The results are shown in Table 1.

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. The results are shown in Table 1.

Example 13 A catalyst was prepared and a reaction was carried out in the same manner as in Example 7, except that rhodium chloride was used instead of palladium chloride. The results are shown in Table 1.

Example 14 A pond using chloroplatinic acid instead of palladium chloride was prepared in the same manner as in Example 7 using catalyst f! -Prepared and reacted. The results are shown in Table 1.

Example 15 A catalyst was prepared and a reaction was carried out in the same manner as in Example 5, except that ruthenium chloride was used instead of nickel chloride. The results are shown in Table 1.

200 g of chloropentafluoroethane'i, 250 g of triethylamine, and 28 g of the palladium catalyst used in Example 2 were placed in a Hastelloy C autoclave having an internal volume of 1 liter and maintained at O'C. Hydrogen was introduced while stirring to maintain an internal pressure of 10 atm, and this was maintained for about 10 hours until hydrogen absorption disappeared. The gas composition was analyzed using a gas chromatograph. The results are shown in Table 1.

Table 1 [Effects of the Invention] As shown in the examples, the present invention provides useful pentafluoroethane (R-125) using chloropentafluoroethane (R-115) as a raw material in a smooth, advantageous and good yield. It has the advantage that it can be manufactured using

Claims (1)

[Claims] 1. Hydrogenation of chloropentafluoroethane in the presence of a hydrogenation catalyst containing any one of platinum group elements, iron group elements, or rhenium, or two or more of these as a main component. A method for producing pentafluoroethane, characterized by reducing it by. 2. The method according to claim 1, wherein at least one chlorine atom in chloropentafluoroethane is removed using at least a stoichiometric amount of hydrogen relative to chloropentafluoroethane. 3. The production method according to claim 1 or 2, wherein the reduction catalyst uses a hydrogenation catalyst supported on an activated carbon carrier. 4. The production method according to claim 1 or 2, wherein the reduction catalyst uses a hydrogenation catalyst supported on an alumina carrier. 5. Carry out the reaction in the liquid phase or gas phase at 0°C to 450°C.
The manufacturing method according to any one of claims 1 to 4, wherein the manufacturing method is carried out at a temperature range of °C.