DE591531C - Process for the synthetic production of ammonia - Google Patents

Description

Process for the synthetic production of ammonia It is known To use contact masses as a carrier for other catalytically active substances, e.g. For example, nickel, palladium, platinum and the like have been deposited on iron. Also has iron-containing catalysts are subjected to anodic oxidation using an electrolytic bath containing alkali compounds, and then reduced.

Catalysts have been proposed for the synthetic production of ammonia been made by heating iron in the presence of lithium compounds and a Oxides from the group of aluminum are produced in a nitrogen-hydrogen stream are ordered. This oxide can also be replaced by an iron cyan compound.

It has now been found that the synthetic production of ammonia with particular advantages, especially at relatively low temperatures, can be carried out if a catalyst is used which is composed of one of oxide melts iron or molybdenum containing contact mass obtained by subsequent reduction exists as a basic substance on which catalytically under the conditions of ammonia synthesis effective cyano compounds are precipitated.

Are the in a known manner, for. B. according to the procedure of the patent 249 447 and its additional patents, iron or molybdenum compounds obtained from oxide melts containing, possibly activated catalysts subjected to reduction, be it with hydrogen or other reducing agents, one obtains metals or in mainly metal-containing mixtures, penetrated by very fine pores and are therefore able to remove other catalytically active substances from the liquid Absorb phase or the gas phase. As such on the catalyst or within Its pores to be precipitated substances are cyano compounds, such as cyanides, in particular of iron, e.g. B. potassium ferrocyanide or ferricyanide, hydrocyanic acid, ammonium ferrocyanide, and similar in water or other, possibly anhydrous liquids, z. B. alcohol, ammonia, hydrazine, glycol, glycerine, formic acid, nitrobenzene, etc., soluble or suspendable compounds are used. You can also use different Cyan compounds, optionally with the interposition of a possibly to be carried out in a vacuum Drying, to be brought to adsorption.

The granular or lumpy produced by the present process, mechanically resistant contact masses combine those with regard to strength and service life favorable properties of their Components while the catalytic effect in many cases, especially when used lower Working temperatures, essentially about the sum of the catalytic effects of the components goes out. One of the main advantages of these catalysts is that they enable operation within a wider temperature range, thereby reducing the The operational safety of ammonia production is significantly increased.

Appropriately, one works in such a way that one creates a Temperature gradient in the contact furnace, the gas flow only through the hotter zone of the furnace, via a contact that is particularly effective at a higher temperature, and then through the cooler oven zone via one in the manner described: through treatment of the first catalyst obtained, effective at low temperature conducts contact.

Example z An oxidizing melting of iron with little Addition of aluminum and possibly potassium nitrate produced ammonia catalyst is reduced with hydrogen at about 50o °. The hard, porous bodies obtained are after cooling in the non-oxidizing medium in a cold saturated solution entered by potassium ferricyanide. After about half an hour of exposure to the solution this is removed and the product obtained, which now absorbs potassium ferricyanide contains, advantageously dried in vacuo at a moderate temperature.

With the catalyst produced in this way and reduced in the contact furnace can at a working temperature of 40o ° compared to the one not with potassium ferricyanide solution aftertreated catalyst obtained ammonia yield a 50% higher yield be achieved.

Example e A nitrogen-hydrogen mixture compressed at Zoo at, which contains 75% hydrogen and: 250 /,) nitrogen, a thorough one is made first Pre-cleaning and then washing with liquid ammonia at low temperature subjected and then passed over a catalyst heated to 4201, the by treating a molten iron contact activated with aluminum oxide with a aqueous solution of potassium ferrocyanide was obtained. This contact mass provided during a period of operation of 30 days lasting about 100% ammonia, during the molten iron contact not treated with potassium ferrocyanide, described in more detail above supplied about 8 per cent. of ammonia. A potassium ferrocyanide catalyst gave under .The same conditions initially about ammonia. The effectiveness of this catalyst however, it subsided very quickly; so he yielded z. B. after 8 days of testing only another 5 a / 0 ammonia.

Example 3 One activated with aluminum oxide, zirconium oxide and potassium oxide Molten iron catalyst was after its reduction at 55o1 with a suspension treated by potassium aluminum ferrocyanide in water. The catalyst supplied 39o ° and zoo at pressure 7 ° / o ammonia, while the above-mentioned molten iron catalyst and that of potassium aluminum ferrocyanide under the same conditions both of them supplied only 5.5% ammonia.

Claims (1)

PATENT CLAIM: Process for the synthetic production of ammonia with catalysts made from cyano compounds and other catalytically active substances are characterized by the use of a catalyst made from one obtained from oxide melts by reduction, containing iron or molybdenum Contact mass exists as a basic substance, on which catalytically in the ammonia synthesis effective cyano compounds are precipitated.