DE886898C - Process for the production of technically pure benzene - Google Patents

Description

Process for the production of technically pure benzene, propane and butane stand as waste gas, e.g. B. in the implementation of carbohydrate processes, available in abundant quantities, without them having hitherto been a sufficient quantity technical, better recovery could be supplied.

It is known to use gaseous hydrocarbons of the paraffin series to convert them into liquid hydrocarbons by splitting the gases into several Working stages passes over different catalysts, being advantageous in one stage work is carried out at increased pressure. Instead of over a large number of proposed Catalysts, the conversion can also be carried out in a gas generator on glowing coke will. However, this results in mixtures of hydrocarbons, which are only small Part made up of benzene.

It is also known that such reactions are also glowing in coke ovens To make coke. However, this coke did not contain any added catalysts, or his reactivity was reduced by the treatment with air or steam, so that there were only low yields of liquid hydrocarbons, which too consisted only partially of benzene.

Finally, it is known to methane and other aliphatic hydrocarbons convert them into liquid hydrocarbons by using the starting materials a thermal treatment subject; with the necessary Heat is taken from gas generating furnaces, built into the special gas inlet ducts are, while the derivation of the reaction products with the other coking products he follows.

It has now been found that gases consisting essentially of propane or butane or a mixture of both, in the simplest way with high yield Can convert these gases into technically pure benzene if you keep these gases at temperatures above 600 °, but advisable not above 97o °, in a single operation over such coke, which has not yet come into contact with air, which passes through Coking of catalysts which have been added with cracking and / or ring-forming catalysts Coal was extracted.

The conversion takes place via the ethylene, which is produced in this process forms intermediate. For the addition of catalytically active contact materials to Coal has proven copper, which is appropriately activated by adding alkali ' and that promotes the conversion of propane and / or butane into ethylene. For the formation of a ring, compounds of the 3rd and 4th groups of the periodic are used Systems, such as B. aluminum compounds, too, their catalytic effect also through The addition of suitable activators can be increased. A particular advantage of the The process consists in the conversion to technically pure benzene in one can achieve a single operation, it is possible to achieve yields of 6o ° / a and in particularly favorable cases of 75% of theory.

It is expedient to carry out the process - a coal use which gives a coke that has a relatively high ash content has, since the ash also promotes the conversion process considerably. With special Advantageously, a coke is used that does not contain any significant amounts of volatile sulfur contains.

The invention will be explained using the following exemplary embodiment: 550 g of coal are converted into coke with the addition of 2% aluminum oxide as a contact substance in the contact space and give 380 g of coke. At a temperature of 85o °, 100 l / h of technical-grade butane are passed over, resulting in gaseous and vaporous reaction products containing 48 g of benzene. This benzene yield corresponds to about 60 % of theory. The gas-vapor mixture with the reaction products it contains is then fed to a cooling device in which the benzene is separated out. The analysis of the boiling point of the latter shows that 6 ° / o pass between 80.1 and 8o.5 °. It can therefore. are referred to as technically pure benzene: The unconverted butane and the ethylene not rearranged to benzene are separated from the hydrogen, whereupon the unconverted hydrocarbons are returned to the conversion zone. ' The hydrogen is expediently separated from the residual gases in that the gases diffuse through porous walls, a strong temperature gradient, for example several 100 °, being maintained between these and the other walls delimiting the diffusion space. Instead of the porous wall, one made of platinum, palladium, iron or nickel can also be used.

The superiority of the present process over the prior art the technique is confirmed by the following comparative experiment: Coal was without special Additives coked in the usual way. About this coke was among those in the above Example given experimental conditions butane passed. The yield of benzene was an average of 14 g / 100 1 butane.

A coal to which 4% Cu0, 0.050 /, NaN03, 3% ale 03 had been added as a contact substance, was coked and butane was again passed over this coke under otherwise constant test conditions. The yield rose to -45 g / 100 1 butane.

Claims (3)

PATENT CLAIMS: i. Process for obtaining technically pure benzene by heating gaseous hydrocarbons in the presence of glowing coke which has not yet come into contact with air, characterized in that gases consisting essentially of propane or butane or a mixture of both are used at temperatures above 600 ° , expediently but not above 97o °, passes in a single operation over coke which has not yet come into contact with air and which was obtained by coking coal mixed with cracking and / or ring-forming catalysts. 2. The method according to claim i, characterized by the use of a coke that does not contain appreciable amounts of volatile sulfur contains. 3. The method according to claims i and 2, characterized in that according to Separation of the benzene formed from the reaction gases, the hydrogen from the Residual gases are separated and the unconverted hydrocarbons wholly or partially returned to the conversion zone.