NO144076B - LEADING DEVICE FOR AIR-CLOSED CLOSING OF AN OPENING IN A WALL, EX. FOR A SLIDER DOOR - Google Patents

Abstract

Guide device for airtight closing of. an opening in a wall, e.g. for a sliding door.

Description

Process for the production of trichlorethylene by hydrogenation of perchlorethylene.

Trichlorethylene can be produced by hydrogenating perchlorethylene (tetrachlorethylene) using a copper catalyst. The reaction formula is:

This method makes it possible to produce trichlorethylene in a cheaper way than by the usual chlorination of acetyl produced from calcium carbide, namely by using the cheap cracking gases from the oil industry. The cracking gases contain lower hydrocarbons that can be chlorinated so that perchlorethylene is formed as the main product.

Use of a pure copper catalyst, e.g. copper chloride, entails certain disadvantages. The conversion ratio will thus be relatively low and varies greatly, resulting in poor reproducibility of the reaction. According to the invention, it has been shown that the turnover ratio can be increased to a considerable extent and that the reproducibility is improved when the copper catalyst contains salts, preferably chlorides, of one or more of the metals potassium, rubidium and cesium. Addition of lithium or sodium to the copper catalyst does not produce this good effect.

Catalysts in the method i

according to the invention can be used in a known manner in connection with a suitable carrier. Granulated active aluminum oxide

can thus be impregnated with a mixture of chlorides of copper and one of the metals potassium, rubidium and cesium in an aqueous solution, after which it is dried. The activity of a catalyst prepared in this way can be increased if they are treated alternately with oxygen and hydrogen at a higher temperature.

The ratio between the amount of copper and the amount of alkali metal can be varied within wide limits. Even a very small amount of alkali metal in the catalyst, e.g. 0.1 per cent, leads to a significant increase in the catalyst's effect. On the other hand, the amount of alkali metal can be many times the amount of copper. In the examples given below, an amount of potassium is indicated which is six times the amount of copper, based on the weight of the chlorides. It turns out that the amount of alkali can be increased to ten or twenty times the amount of copper, and probably even more.

Perchlorethylene and hydrogen should preferably be present in approximately equimolecular amounts. It is preferred to use gas mixtures in which the amount of hydrogen does not deviate from the amount of perchlorethylene by more than 10 percent, based on the molecular weights.

The reaction is preferably carried out

at normal pressure.

The temperature of the gas mixture should be 200-325° C. Temperatures in the range 250-300° C are preferred. The minimum temperature is chosen so that the desired reaction rate is achieved, and the maximum temperature is chosen so that perchlorethylene does not decompose to a significant extent, and so that the catalyst does not evaporate.

It turns out that the reaction improves

when the gas which is led to the catalytic converter in-

keeps oxygen in such small quantities that explosive mixtures with hydro-

gene, preferably around or less than 3 volume percent of the hydrogen's volume.

This small amount of oxygen reduces dan-

of dichloroethylene, and it turns out that it increases the reaction rate and makes possible

makes use of lower reaction tempe-

return.

Example 1.

Granulated active aluminum oxide is impregnated with an aqueous solution containing

end approx. 5% CuCl and 30% KC1 are dried and treated alternately with oxygen and hydrogen at approx. 300° C. A gas mixture of equimolecular amounts of perchlorethylene and hydrogen is led into contact with this catalyst at normal pressure and at a temperature of approx. 300° C. The mixture of chlorinated hydrocarbons that can be condensed from the gas mixture after the reaction contains approx. 65 percent trichlorethylene. Resi-

duet consists of unreacted perchlorethylene and a few percent lower chlorinated products. The turnover ratio can be increased considerably

over 65 per cent by e.g. to increase the contact time between catalyst and gas mixture, but this also leads to the formation of a

clear amount of unwanted by-products. There-

as the turnover ratio is reduced to 50

pst., almost pure trichlorethylene will be produced during the reaction.

Example 2.

The following experiments are carried out to illuminate the effect of the invention in contrast to the relatively low effect of pure copper catalysts or copper catalysts containing lithium and sodium. Six catalysts are prepared as indicated in example 1. The first catalyst contains pure

CuCl2 on aluminum oxide carrier, the other catalysts contain CuCl2 and different

equal alkali salts, namely LiCl, NaCl, KC1,

RbCl and CsCl. These six catalysts an-

is reversed by hydration of perchlorethylene in an equimolecular mixture with hydrogen,

at different temperatures. The results appear in the table:

The turnover ratio when applying

pure CuCl2 as catalyst was in the aforementioned experiment approx. 20 per cent, but as the experiment is not reproducible, the turnover ratio can be significantly lower in another experiment. The turnover ratio when adding li-

thium and sodium were relatively low, and satisfactory conversion conditions were only achieved by using catalysts in the process according to the invention

Nelson. The most effective catalyst was the one containing cesium, this one did

possible to work with low temperatures,

only slightly above 200°C.

The salts used in the experiments were chlorides, but catalysts in the process

the method according to the invention can also be prepared using other salts of copper, potassium, rubidium and cesium.

Claims (3)

1. Process for the production of trichlorethylene by hydration of perchlor- ethylene in the presence of a copper catalyst, characterized in that the reaction mixture of perchlorethylene and hydrogen is brought into contact with a catalyst containing salts, preferably chlorides, of copper and one or more of the metals potassium, rubidium and cesium at a temperature of 200 -325° C, preferably 300° C. 2. Method according to claim 1, characterized in that the gas mixture also contains a small amount of oxygen, preferably in an amount of approx. 3 volume percentage, based on the amount of hydrogen. 3. Method according to claim 1, characterized in that the temperature, the contact time and the ratio between perchlorethylene and hydrogen are regulated so that the conversion ratio after the gas mixture has passed the catalyst once is approx. 50 percent