DE1078100B - Catalysts for the catalytic oxidation of hydrogen chloride - Google Patents

Description

Catalysts for the catalytic oxidation of hydrogen chloride In the production of chlorine from hydrogen chloride and oxygen or oxygen-containing Gases after the Deacon process 4HCl + 02--2H30 + 2Cl2 have always been responsible for volatility the catalytically active components of the catalyst at the reaction temperatures from 300 to 5500 C considerable difficulties. This is especially true for the catalytically highly effective salts of copper, which are found in almost all of the corresponding Catalysts are included as a crucial component. The volatility of the Copper salts have a disadvantageous effect in practical operation by decreasing the catalytic activity of the contact grains and by adding contact grains in other places by the volatile copper chloride. It therefore has no attempts it fails to reduce the volatility of the catalytically active components. this can happen once by using, for example, the melts of copper chloride, Ferric chloride and potassium chloride can be used. On the other hand, one strives to be catalytic to find effective metal salts that have a lower volatility than copper salts exhibit. This fact is particularly important when the catalytic effective salt is applied to an inert contact carrier. For example the use of rare earth salts or chromium oxide or mixtures of both on an inert carrier. The connections just mentioned show only one poor catalytic effect and are not suitable for practical use. For example, in the patent literature for a contact with rare earths on pumice stone only a yield of 50/0 of the theoretical (thermodynamic) maximum Possible given a test temperature of 450 to 4600 C. According to their own Investigations with a chromium oxide contact the conversion is 9% of the thermodynamic one Possible (68 ° / o C12 in equilibrium) at a temperature of 4300 C and more stoichiometric Composition of the starting gases according to the above equation.

It therefore represents a technical advance, catalysts find the ones free of the highly effective but volatile copper compounds are and still an optimal reaction yield in the context of the Deacon process deliver. An optimal reaction yield will be that at a given temperature understood thermodynamically maximum possible.

It has now been found that when using the invention Catalysts, in which salts or oxides of the rare earths, of silver and of uranium or thorium or both on inert carriers such as kaolin, silica gel, Kieselguhr, pumice stone, etc. are applied for the catalytic oxidation of Hydrogen chloride the requirements described above are met.

As salts of rare earths, silver, uranium and thorium the nitrates are well suited, but also the chlorides and others. can be used.

The most advantageous mixture of metal salt and carrier substance is approximately 5 to 40 percent by weight metal salt in contact. The reaction can range from 450 to 5300 C, advantageously at 4800 C.

The catalyst according to the invention is retained even after prolonged periods of operation its full effectiveness and shows an unchanged good appearance.

In the examples, SE means a rare earth metal.

Example 1 60g SE (NO3) 3, 12g AgNO3, 12g Th (NO3) 4 and 12g UO2 (CH3COO) 2 are dissolved in water to 250 ml of solution, with 300 g of kaolin and 80 g of silica gel powder mixed, thoroughly kneaded and formed into elongated moldings of 4 mm in diameter pressed.

For the catalytic conversion are in an Ouarzrohr with an inner diameter of 44 mm and a length of 1 m a 400 mm long contact layer, that corresponds about 600 cm3, filled. At a temperature of 4800 C, 10 cm3 of hydrogen chloride became and 2.5 cm3 of oxygen passed through it per second.

With the contact according to Example 1 were under the abovementioned conditions 62 ° / o, i.e. H. the full thermodynamically possible yield of chlorine at this temperature achieved.

Example 2 60-g SE (NO3) 3, 12gAgNO3, and 12gTh (NO3) 4 are in water dissolved to 250 ml of solution, mixed with 300 g of kaolin and 80 g of silica gel flour, thoroughly kneaded and pressed into elongated moldings.

The chlorine yield is under the same reaction conditions as in example 1 60e / o, d. i.e. the full thermodynamically possible yield this temperature.

Example 3 60g SE (NO3) 3, 12g AgNO3. and become 12g UO2 (CH3COO) 2 in water to 250 ml of solution dissolved, mixed with 306 g kaolin and 80 g silica gel flour, kneaded and pressed into elongated moldings.

Under the same conditions as described in Example 1, is the yield of chlorine 62%.

Claims (1)

PATENT CLAIM Catalysts for the catalytic oxidation of hydrogen chloride, characterized in that salts or oxides of rare earths, silver and of uranium or thorium or both on inert carriers such as kaolin, silica gel, Kieselguhr, pumice stone, etc. are upset.