DE662447C - Process for the production of hydrocyanic acid - Google Patents

Description

Process for the Production of Hydrocyanic Acid The invention relates to a process for the production of hydrocyanic acid. It is based on the realization that by treating cyanamide, of a possible 'lichst has low oxide content, with completely dry hydrogen chloride at a temperature of about 55o to iioo' is formed C hydrogen cyanide. The treatment is expediently carried out with the addition of carbon.

It has already been proposed to produce cyan sodium by heating a metal cyanamide with sodium chloride in the presence of carbon. This known method is a melting process in which reaction mixtures are melted together in an electric furnace. Since -UM is an endothermic process, a lot of heating current is used. In contrast, the method of the invention involves an annealing process which is exothermic. The results of the two processes are correspondingly different: The known processes result in a very impure molten cyanide with a cyanide content of at most 40 to 50 "/ 0; the process of the invention, on the other hand, produces hydrocyanic acid, which immediately becomes pure, high-percentage cyanide when introduced into alkalis or ferrocyanide or, if desired, can be used as it is, e.g., in the pest control industry or otherwise.

You can use the process described for the production of hydrocyanic acid achieve an increased yield by adding the hydrogen chloride of gases such as hydrogen, nitrogen, carbon dioxide and the like, diluted or but gas mixtures such as generator gas, water gas, luminous gas are used for this purpose. By The addition of these gases prevents the decomposition of the hydrogen cyanide and the ammonia formed at the same time. To dilute the hydrogen chloride one can also those formed during the reaction after the hydrogen cyanide has been leached out Use gases, and you then get that the ammonia that is in the reaction gases can be contained by renewed addition to the reaction in hydrogen cyanide can be transferred. Carbon can be in the form of pulverized coal, charcoal, coke or soot can be added.

Calcium cyanamide forms hydrogen cyanide with hydrogen chloride at a temperature of 550 to 1 100 ' C according to the equation: CaC N, + 2 H Cl + C = CaC1, + 2 H C N. The gases that react must be dry so that Ammonia according to the formula: CaCN2 + 3 H20 = CaCO3 + 2 NH, 9 is prevented as far as possible.

Since technical cyanamide contains oxides, the formation of ammonia cannot be completely prevented, since the reaction of the hydrogen chloride with the oxides forms not only chloride but also water, which together with cyanamide results in ammonia.

Hydrogen cyanide is produced by the intravenous action of hydrogen chloride on cyan at a temperature of about 50000 'C; the yield increases with increasing temperature.

The following experiments explain the process: 20 g calcium cyanamide with -24.5 % N and 2.3% 0 content, mixed with 10 g anhydrous charcoal, were raised to 10 ° C in the first test and to 10 ° C in the second test 65o 'C heated. The air in the apparatus was previously displaced by passing hydrogen through it. As soon as the temperature of 100 ° C. or 65 ° C. was reached, an undiluted stream of hydrogen chloride was passed through the reaction tube at a rate of 5 liters per hour. The hydrogen chloride was dried with calcium chloride before entering the reaction tube. The reaction gases were passed through dilute sodium hydroxide solution, in which the hydrogen cyanide was collected, and then through dilute sulfuric acid, in which the ammonia was bound. As soon as the gas emerging from the reaction tube no longer contained any hydrogen cyanide, the experiment was terminated. The cyanogen and ammonia content was determined in the sodium hydroxide solution and in the sulfuric acid.

Result is: i. Terap. II ool C, undiluted hydrogen chloride, rate 5 l / hour: 2.76 g of cyanide-N., 0.58 g of ammonia-N.

: 2. Temp. 65o ' C, undiluted hydrogen chloride, speed 5 l / hour: 2.249 (# yanid-N., 1.28 g ammonia-N.

A mixture of: 20 g calcium cyanamide with 24.5 l /. N and 2.3% O content with 10 g of anhydrous charcoal are heated in a hard-paste porcelain reaction tube. Dry hydrogen was passed through the tube during the heating. As soon as the desired reaction temperature was reached, dry hydrogen chloride was passed through the reaction tube, which in the first experiment was diluted with hydrogen in the ratio -i: io and in the second experiment with luminous gas in the ratio i : 2o. The diluted Chforwasserstoff was passed per hour on the first attempt at a rate of 1 io and the second attempt with 2o. 1 The gases introduced were dried with chlorealcium. The diluted hydrogen chloride was so long passed through the tube, which was heated on the first attempt to 9To 'C and the second attempt to iioo' C, until the gas which came out of the reaction tube, no hydrogen cyanide and no ammonia, 'Pthielt, whereupon the reaction residue in the tube l #. to cool with a stream of hydrogen. The gases emerging from the reaction tube, which contain hydrogen cyanide and ammonia, were passed through a sodium hydroxide solution in which the hydrogen cyanide was collected, while the ammonia was then absorbed by dilute sulfuric acid.

On the basis of analyzes, the reactions gave at 95o 'C, diluted with hydrogen i: io io and 1 hour each, 3.07 Cyanidstickstoff 9, 0.86 g ammonia nitrogen; 1 100 ° C, diluted with luminous gas i : -, o and: 2o 1 per hour, 3.22 9 cyanide nitrogen, 0.41 g ammonia nitrogen.

The apparatus for carrying out the method can be set up in this way be that the reactions that are carried out take place under negative pressure, this prevents hydrogen cyanide from escaping through the leak in the apparatus will. The supply of the gas mixture is practically set up so that the gas enters that part of the reaction space from which this is achieved by the reaction resulting and now cooled calcium chloride discharges, while drying it of hydrogen chloride is used. No Iron can be used as this causes the decomposition of hydrogen cyanide. It is necessary to adjust the flow rate of the hydrogen chloride so that no hydrogen chloride is present in the end gases; the speed is depending on the amount of cyanamide and the heat of reaction.

Hydrogen cyanide obtained in the manner described can be prepared according to known methods Processed on hydrocyanic acid or on cyanides and ferrocyanides will.

Claims (2)

PATENT CLAIMS: i. A process for the production of hydrocyanic acid, characterized in that cyanamide with minimal oxide content after the addition of carbon in the form of coal, charcoal, coke, carbon black, o. The like. At a temperature of 55o to iioo 'C and at ordinary or reduced pressure with Treated dry hydrogen chloride, the flow rate of the hydrogen chloride must be adjusted so that hydrogen chloride cannot occur in the end gas. e 4 after 2. Claim Ausführungsforni i, da-through in the, Verfat # proceedings' that the hydrogen chloride is the appropriate gas, such as hydrogen, nitrogen, carbon monoxide, hydrocarbons, or with Gasgernischen as producer gas, water gas or coal gas diluted with an at-19 .