PL101954B1 - A METHOD OF PRODUCING CHLOROCYAN - Google Patents

Description

Patent description was published: August 30, 1979 101954 Int. Cl2.

C01C 3/00 READING ROOM U -du Paientowy | Inventor: The holder of the patent: Deutsche Gold- und Silber-Scheideanstalt Vormals Roessler, Frankfurt (Federal Republic of Germany) Method for producing chlorocyanate The subject of the present invention is a process for the production of chlorocyanate from hydrogen cyanide and chlorine hydrogen.

It is known from German patents Nos. 2027957 and 2131383 to produce chlorocyanate by reaction hydrogen cyanide and hydrogen chloride with hydrogen peroxide in the presence of an aqueous solution of copper ions and iron as catalysts.

The reaction yields about 90-92% for hydrogen cyanide, with the slight decomposition of hydrogen peroxide and the oxidative saponification of hydrogen cyanide occurring in chlorocyanate gas up to 5% by weight of dene and up to 5% by weight of carbon dioxide.

During the trimerization of chlorocyanate to cyanuric chloride, the oxygen present in the chlorocyanate affects the increasing the consumption of activated carbon, which hinders the continuous production of cyanuric chloride, because more often the process should be interrupted to replace the carbon.

It was found that chlorocyanate with practically no oxygen and nitrogen is produced completely continuous, if hydrogen cyanide and hydrogen chloride or hydrochloric acid react under increased pressure with hydrogen peroxide in an aqueous environment in the presence of copper and iron ions. This is how you get chlorocyanin deprived of oxygen and nitrogen. Here, if appropriate, reactants such as hydrogen chloride or acid The salt is wholly or partially produced directly in the catalyst solution introduced into the circuit ra, consisting of copper and iron ions, by the reaction of chlorine with hydrogen cyanide, which can be run both under pressure and non-pressure method.

The formation of the hydrogen chloride or hydrochloric acid at the point in the circuit is preferred the circulating medium contains practically no hydrogen peroxide.

The reactions proceed according to the following formulas: 1) HCN + CL2 - * C1CN + HCl 2) HCl + HCN + H202 Cu ^> Fe3 + ClCN + 2H20-53.5kkal / mol2 101954 The advantage of carrying out the process according to both equations 1 and 2 is that the chlorine completely turns into chlorine cyan without obtaining hydrochloric acid which has to be separated. So there is no need to prepare * no machine room for hydrochloric acid. Reactions 2 can be carried out in the reactor shown in Figure 3. Both reactions 1 and 2 can be carried out in either the reactor shown in Figure 1 or either of the reactions separately in a separate reactor as shown in Fig. 2.

As already mentioned, chlorination of hydrogen cyanide can be carried out under increased pressure or in normal small.

Preferably, the chlorination reactions of hydrogen cyanide are also carried out under a pressure of 1.5-16 ^ apWTK ^ bars- and "" * "it is surprising that the application of increased pressure not only does not inhibit the course of the reaction, but even facilitates it, although from the sum formula 2 we should expect the opposite because at a pressure of 1 bar the chlorocyanate evaporates from the reaction solution and this could TOledimtafc ha equality of reaction.

On the other hand, it turned out that the chlorocyanate dissolves completely when using increased pressure water in the reaction solution and the conversion of hydrogen cyanide, and thus the chlorocyanate yield, increased significantly sta.

Moreover, it was not expected that the chlorination reaction would take place in the catalytic solution according to Equation 1 tora under pressure without side reactions.

The separation of chlorocyanin from oxygen, nitrogen and most carbon dioxide is carried out on a large basis the difference between the solubility in the reaction solution under increased pressure of chlorocyanate and from a slight decomposition of oxygen hydrogen peroxide, namely, insoluble in the reaction solution gases such as oxygen, nitrogen and carbon dioxide are withdrawn at the top of the reactor. These gases are released from chlorocyanin in the pressure washer and drained through the pressure valve.

In this way, chlorocyanate gas is produced by expansion of the reaction solution, which contains almost no oxygen and can be used without any further purification, only after drying it trimerize to generate cyanuric chloride.

The process for producing chlorocyanin according to the invention is also carried out in a completely continuous manner as well according to German Patent Specification No. 2,027,957 and 2,131,383, i.e. the catalyst solution used, consisting of from copper and iron ions, is separated during the process and recycled back into the reaction.

Also in this case, water should be recycled with hydrogen peroxide and hydrochloric acid pull out together with the water formed during the reaction. This can be carried out by the methods described in the patent specification German wording no. 2131383.

Removal of the water introduced with the reactants and the water formed from the circuit has proved to be extremely advantageous during the reaction together with the catalyst solution, namely through an ion exchanger The ionic ion binds copper and iron ions, and the leaking solution is discarded. By this way of proceeding the copper and iron ions are recovered, but the recycle solution is only saturated to a certain level in the ammonium chloride formed in the catalyst solution by the oxidative saponification of hydrogen cyanide, because it is not bound by the ion exchanger, but is disposed of with the waste water.

A slightly altered procedure has proved to be advantageous in that a liquid is used for the reaction Hydrogen cyanide stabilized with phosphoric acid. In this case, the ion exchanger is too concentrated after administration the catalyst solution is treated with mineral acid not immediately, but only after washing it previously intermediate alkaline substances, such as diluted alkaline liquors or solutions alkaline salts, such as with carbonates or acetates.

Commercial cation exchangers are used as the ion exchangers. Resins are suitable ion exchangers based on polystyrene or polystyrene-divinylbenzene system. Preferably, macroporous ones are used exchangers based on polystyrene with slightly acidic active exchange groups.

After saturation with the catalyst solution, the exchanger is washed, the copper and iron ions are separated thin mineral acid, preferably 1-10% by weight aqueous hydrochloric acid, and then recycled for circulation in a concentrated form of the said catalyst solution.

The higher the concentration of the feed catalyst solution, the more water can be drawn off unit of time.

In order to maintain an optimum concentration of the catalyst constantly, it is very advantageous to draw in a fashion continuously and continuously recycling the regenerated catalyst solution.

In carrying out the process by the method of the invention, it is desirable to hold for a duration pH values of 0.1-0.5, especially 0.25-0.35, and temperature settings in the range of 40-60 ° C, especially approx. 50 ° C. 101954 3 The heat generated during the reaction is used in part to maintain the reaction temperature and the excess heat is used to maintain the reaction temperature its measure must be discharged by cooling. .-. .

By applying the above-mentioned treatments, the formation of the cyanide can be largely avoided and the decomposition of hydrogen peroxide is kept within narrow limits.

Hydrogen cyanide is used in the reaction in its usual form, in particular in gaseous or liquid form. Chlorine dór is also used in gaseous form or as an aqueous solution containing 0.5-36% by weight of hydrogen chloride, preferably 8-20% by weight. Hydrogen peroxide is used in the form of commercial solutions, for example as a solution containing 25-95% by weight, preferably 30-50% by weight of hydrogen peroxide.

The reactants should be used in approximately stoichiometric amounts, for example hydrogen cyanide, chlorine hydrogen and hydrogen peroxide 0.9-1.1 mol each.

The yield of chlorocyanate with respect to water peroxide is most preferred with optimal catalyst concentration, which is 0.077 mole of copper per liter of recycle solution and 0.0125-0.025 mole of iron per liter. Higher or lower concentrations can be used, but this has no beneficial effect on performance chlorocyanin. In general, 0.5-0.005 moles of copper and iron are used per liter of recycle solution.

The reactions are carried out in conventional reaction tubes which, however, are provided with a connection on the top drainage bag for waste gases.

In the process according to the invention, the conversion of hydrogen cyanide to chlorocyanin is considerably greater in comparison in a process carried out under normal pressure, whereby the proportion of hydrogen cyanide is significantly reduced in the gas and at the same time obtaining the chlorocyan in higher yield.

Besides, the produced chlorocyanin contains practically no oxygen so that the reactions of triomerization of it to Cyanuric chloride is carried out much simpler than before.

A further advantage of the direct chlorination of hydrogen cyanide compared to the hitherto used process The result of the reaction is that the hydrochloric acid obtained by chlorination can be immediately converted into chlorine the cyan is eliminated by this separation of the hydrochloric acid. The method according to the invention is explained in the following examples where the percentages relate to percentages by weight.

Example 1 The technical apparatus shown in Fig. 1 is circulated through the reactor I, its upper part II, expansion chamber III and flush VI 45 liters of aqueous solution, containing per liter 13.0 g of CuCl2 • 2H2O and 6.7 g of FeCl3 • 6H2O. Via line 1, 1.6 kg / hour of liquid hydrogen cyanide are metered in 0.1% H3PO4 stabilized and this solution is transferred via line 8 by means of pump 8a to reactor I.

Through line 3, chlorine gas is added at a rate of 2.0 kg / hour, thereby converting half the amount of hydrogen cyanide into the turns into chlorocyan and hydrogen chloride.

The gaseous chlorocyanine formed in the closed pressure valve 5a of the reactor I with the upper part II and in a pressure pad V pressure approx. 3 bar, from which the chlorocyan goes into solution in an amount up to 5%. The catalyst solution, containing chlorocyanate, is led through line 6 and an expansion valve 6a into the expansion chamber III.

The solution, containing about 1-2% of chlorocyanin, is then recycled through line 7 through flush VI, line 8 and pump 8a to reactor I. Via line 2, 2.22 kg / hour of 50% hydrogen peroxide are added here, represents a 10% excess over the equivalent amount. This peroxide converts the hydrochloric acid obtained from the chlorination reaction in reactor II with the other half of the amount of hydrogen cyanide also in chlorocyanine.

In a continuous process for the production of chlorocyanin, therefore, it is consumed continuously in the recycle solution, and contains catalyst, the total amount of hydrogen cyanide and hydrochloric acid formed during the chlorination and the The pH in the circulating solution is constantly kept at 0.25-0.35.

A mixture of gases such as oxygen, nitrogen and carbon dioxide, formed by a slight decomposition of peroxide of hydrogen, and by the oxidative saponification of hydrogen cyanide, it collects in the upper part II 'of reactor I and hence goes through the line 5 to the pressure flush V, where it is washed from chlorocyanin and discharged through the valve pressure 5a. The solution required for the pressure washer is taken from the expansion chamber III via line 10 and valve 10a, degasses it in column IV and sends it through line 11 by means of pump 11a to the washer Pressure line V. From there it goes through line 13 through pump 13a back to reactor I.

The water introduced into the recirculation solution with hydrogen peroxide is drawn off together with the resulting water during the reaction, it leads through line 9 and through the expansion valve to VII for degassing, whereby the opening of the line 9 is below the chlorine gas supply line 3.

The catalyst solution taken from the marked place contains only about 0.4% of hydrogen chloride, a no longer contains hydrogen peroxide.

This degassing catalyst solution in column VII is routed through line 15 and through valve 4a or 4b to the VIII ion exchangers, where it is freed from copper and iron ions, and then route 16 to the sewage. Each saturated exchanger column is regenerated in such a way that 4 101954 first washing it with 0.5% aqueous sodium hydroxide solution to remove phosphoric acid, and then introducing Conducts the 4 line with 10% hydrochloric acid to recover the copper and iron ions. Freshly obtained solution of the catalyst is recycled through line 17 by pump 17a and line 8.

The gas exiting from line IV 12 and from line VII 14 contains mainly no chlorocyan Hydrogen cyanide reacted in reactor I, which is washed out in VI and returned to reactor 1 via line 8 with pump 8a.

Example II. In the technical apparatus shown in Fig. 2, they are recycled through the reactor oxidation I, expansion chamber III, chlorination reactor II, expansion chamber IV and back to reactor I 65 liters of aqueous solution, containing in 1 liter 13.0 g of CuCl2 • 2H20 and 6.7 g of FeCl3 • 6H20.

Via line 1, 0.8 kg / hour of liquid hydrogen cyanide stabilized with 0.1% of phosphoric acid are dosed. and this solution is chlorinated to give chlorocyanate in reactor II by adding 2.0 kg of chlorine per line 4 hour.

The chlorocyan thus formed produces a pressure of about 3 bar in a closed-pressure reactor 1 l, under which the chlorocyan goes into solution up to 5%. When the set pressure is exceeded, the solution is it goes to the expansion chamber IV, where its chlorocyan content drops to 1-2%. The solution spreads it is directed via pump 12a to the oxidation reactor I, then hydrogen cyanide is dosed to it via line 2 in the amount of 0.8 kg / hour.

Through line 3, 2.22 kg / h of 50% hydrogen peroxide is introduced, which is a 10% excess then The hydrochloric acid (1.08 kg HCl) formed in the reactor II reacts with hydrogen cyanide to give also chlorocyanate. Rise These gases also generate a pressure of about 3 bar in the reactor I, which is kept constantly by the valve pressure 6a. The catalyst solution with the chlorocyanate dissolved therein is led through expansion valve 7a into the expansion chamber III, from where the released chlorocyan escapes through line 21, connects with chlorocyan from the conduit 22 leading from the expansion chamber IV and are directed together for drying, and stomps for trimerization.

The diluted solution in III is directed through line 8 to flushing VII, where the off-gas comes it is washed from the degassing from columns V and VIII from hydrogen cyanide. The washing liquid is transported dem 10 by means of pump 10a to the chlorination reactor II.

The acidic catalyst solution passes from expansion chamber IV through line 13 and through valve 13a to V for degassing and flocks through line 14 and through pump 14a to the pressure washer VI. where it washes the chlorine cyan from the gas mixture discharged by valve 6a, consisting of oxygen, nitrogen and carbon dioxide. Solution the eluent is routed through line 15 by pump 15a to reactor I.

The sewage, containing 0.3-0.4% hydrochloric acid, is extracted with the III line 9 and valve 9a, degassed in VIII and directs the line 16 n through the valve 5a or 5b to the IX ion exchangers, where the they remain copper (Cu4) and iron (Fe4 **).

As the ion exchanger stops the copper and iron addition to the phosphoric acid, this acid is first washed with 0.5% aqueous sodium hydroxide solution, and only then the cupric ions and zeal are eluted and recycle them.

The effluents are routed through conduit 23 to the canal, the amount being 2 liters / hour.

Commercially available cationic ion exchangers are used as the ion exchangers. The answer Thus, they are not ion exchange resins based on polystyrene or the polystyrene-divinylbenzene system. Macro porous exchangers based on polystyrene with slightly acidic active exchange groups.

In order to separate the phosphoric acid, salt solutions are used in addition to the alkaline liquors alkali, such as carbonates or alkali metal acetates.

Example III. The continuously operating apparatus shown in Fig. 3 is entered into circulation through reactor I, expansion chamber II, flush III, degassing column IV and pressure flush wa V, 40 liters of a solution containing in 1 liter 13.0 g of CuCl2 -2H20 and 3.35 g of FeCl3. • 6H20.

Through line 1, 1.6 kg / h of gaseous hydrogen cyanide is added to line 10 of the reaction solution which is transferred by pump 10a to reactor I. To reactor I is introduced via line 3 by means of pump 3a 50% aqueous hydrogen peroxide solution in the amount of 4.301 kg / hour, i.e. % excess in relation to the stoichiometric amount, and via line 2 pump 2a 10% aqueous hydrochloric acid in the amount of 21.6 kg / hour.

By controlling the addition of hydrochloric acid, the pH of the solution is kept exactly within the range during the reaction cach 0.25-0.35. The liberating chlorocyanate creates a pressure of up to 4 in the reactor I and the pressure washer V bars, which is kept constantly by the pressure valve 6a on top of the flush pressure. In the upper part of the reactor I, oxygen is collected, released by the decomposition of hydrogen peroxide and secondary gases such as carbon dioxide and nitrogen from oxidative saponification and reactions 101954 5 The reaction temperature is kept around 50 ° C. Chlorocyanin dissolved under prepared pressure in the catalyst solution passes through the conduit 7 and the expansion valve to the expansion chamber II. Here, the concentration of chlorocyanate in the solution is reduced from about 5% to about 1-2%, so that during circulation it becomes approximately 100 liters / hour, approximately 3.5 kg of chlorocyan may be released.

Part of the catalyst solution obtained in the lower part of expansion chamber II is directed to line 9 through valve 9a to column IV, where the degassing process of chlorocyan acid takes place at a temperature of 100 ° C hydrocyanic acid and carbon dioxide. 40 liters of catalyst solution are degassed for 1 hour. Hence a degassed catalyst solution of 16 liters / hour is fed through line 12 by means of pump 12a. to the pressure washer V, where the gas mixture collected at the top of the reactor flows through the conduit 5, which it is washed from the chlorocyanate and through the line 6 and the pressure valve 6a it is expanded and released.

The rinsing solution is directed back to the reactor I by means of pump 13a through conduit 13, The gas escaping from column IV contains, apart from chlorocyanate and carbon dioxide, some of the hydrogen cyanide in reactor I, which is leached from the gas mixture in catalyst solution introduced through line 8.

The washed gas escapes through the line 17 and, after connecting with the flowing gas through the line 18, goes to trimerization reaction by a drying tower, which is not shown in the figure. Run off of the flush III is headed back to reactor I via line 10, to which also hydrogen cyanide is added, via pump 10a together with the pressure washer solution V, supplied via line 13 by pump 13a.

The wastewater is extracted at the rate of 25 liters / hour by means of the degassed catalysis solution The tide is directed through conduit 14 and valve 14a, optionally via valve 4a or 4b to ion exchangers VI.

Here, copper and iron ions are retained, and the effluents containing ammonium chloride are discharged to channel. The copper and iron ions are recovered by washing the exchanger columns with 10% hydrochloric acid alternately saturated metals.

The fresh catalyst solution obtained in this way is returned to the reactor via line 15 via the line pump 15a to maintain an appropriate ion concentration.

The average yield of chlorocyanate in relation to hydrogen cyanide is 96.2% of theoretical amount.

The chlorocyanin thus obtained contains 0.1-0.3% of dicyan, 0.5% of hydrocyanic acid and less than 0.5% of carbon dioxide. and nitrogen. The gas chromatographic method does not detect oxygen by analysis.

Example IV. With the same apparatus as shown in Fig. 3 as described in the example III is put into circulation 40 liters of solution, containing per liter 13.0 g of CuCl2 • 2H20 and 6.7 g FeCl3 • 6H20.

1.6 kg / h of liquid hydrocyanic acid are added via line 1 and 10 to reactor I by means of pump 10a. ru stabilized with 0.1% H3PO4. In line 10, hydrogen cyanide connects to the reaction solution.

Via the line 3, by means of the pump 3a, 50% aqueous hydrogen peroxide is introduced into the reactor I 4.3 kg / hour, i.e. a 10% excess with respect to the stoichiometric amount, and through the conduit 2, pump 2a is 27.0 kg of 8% aqueous hydrochloric acid are obtained. The pH value is checked with a pH electrode and is kept within 0.25-0.35 by appropriate addition of hydrochloric acid.

The course of the reaction is the same as that described in example III. The amount of waste water discharged here increases to about 30 liters due to the use of more diluted hydrochloric acid.

Extraction is carried out as described in example III with the addition that the ion exchanger is it is washed first with phosphoric acid with 0.5% aqueous sodium liquor and only then the copper and iron ions are eluted as described in example III and returned to the reaction.

The yield is approximately 96% of the theoretical amount. The degree of purity of the obtained chlorocyanin is the same as given in example III.

The method according to the invention can also produce cyanogen bromide.

Claims (16)

Patent claims 1. The method of producing chlorocyanin by the reaction of hydrogen cyanide and hydrogen chloride or hydrochloric acid with hydrogen peroxide in an aqueous medium in the presence of copper and iron ions, with n a m and e n n-h: y t y m, that the reactions are carried out under increased pressure. 2. ¦ 2. The method according to p. The process of claim 1, wherein the reactions are carried out at a pressure of 1.5-16 bar. 3. The method according to p. 2. The process of claim 1 or 2, characterized in that the reactions are carried out at a pressure of 2 to 4 bar. 6 101954 4. The method according to p. The process of claim 1, wherein the reactions are carried out at a pH value of 0.1-0.5. 5. The method according to p. 1, where the reactions are carried out at a pH of 0.25-0.35. 6. The method according to p. The process of claim 1, wherein the reactions are carried out at a temperature of 40-60 ° C. 7. The method according to p. 1, where the reactions are carried out in the presence of 0.077 mol / liter of copper ions and 0.0125-0.025 mol / liter of iron ions. 8. The method according to p. A process as claimed in claim 1, characterized in that the water introduced with the reactants and the water generated during the reaction are withdrawn from the circuit by cation exchangers together with the catalyst solution consisting of copper ions. 9. The method according to p. The method of claim 1 or 8, characterized in that macroporous polystyrene-based exchangers with weakly acidic active exchange groups are used as the cation exchanger. 10. The method according to p. The method according to claim 8, characterized in that, in the case of presence of phosphoric acid in the withdrawn catalyst solution, the treatment of the cation exchanger with mineral acid is carried out after prior treatment with substances having an alkaline reaction. 11. The method of producing chlorocyanin by reacting hydrogen cyanide and hydrogen chloride or hydrochloric acid with hydrogen peroxide in an aqueous medium in the presence of copper and iron ions, characterized in that the reaction is carried out under increased pressure, the reagents such as hydrogen chloride or acid The salt is completely or partially produced directly in the circulating catalyst solution, consisting of copper and iron ions, by the reaction of chlorine with hydrocyanide, possibly carried out under increased pressure. 12. The method according to p. A process as claimed in claim 11, characterized in that the process and possibly also chlorination of hydrogen cyanogen are carried out at a pressure of 1.5-16 bar. 13. The method according to p. The process according to claim 11 or 12, characterized in that the process is carried out at a pressure of 2-4 bar. 14. The method according to p. 11, with the fact that the water introduced with the reactants and formed during the reaction is removed from the circulation together with the catalyst solution, consisting of copper and iron ions, through cation exchangers. 15. The method according to p. A method according to claim 14, characterized in that macroporous polystyrene-based exchangers with weakly acidic active exchange groups are used as cation exchangers. 16. The method according to p. The method of claim 1, characterized in that, in the case of the presence of phosphoric acid in the discharged catalyst solution, the treatment of the cation exchanger with mineral acid takes place after prior treatment with substances having an alkaline reaction. Fig. 1101 954 21 acN Fig. 2 M TT 7a li 17 and UsoA 16 2at 13 HCN e acN 9a N IIN h2 IV 15a ~ * 13a iSa J 10. © Ihci 12a Ju -i 4aX X4b * VI Fig. 3