DE2106019A1 - Process for the preparation of sulfamic acid - Google Patents

Description

FARBWERKE HOECHST AKTIENGESELLSCHAFT
formerly Master Lucius & Brüning

Date: February 8, 1971 - Dr.BK / Ba File number: - HOE 71 / ^F

Process for the preparation of sulfamic acid

The invention relates to a process for producing sulfamic acid by reacting sulfur trioxide with ammonia in the gas phase and hydrolysis of the reaction mixture formed with mineral acid.

The reaction of sulfur trioxide with ammonia in the gas phase to a mixture of the ammonium salts of sulfuric acid, sulfamic acid, imidodisulfonic acid and nitrilotrisulfonic acid is z. B. known from German patent specification 903 571. The heat of reaction must be discharged through the wall of the reaction chamber. In general, it is difficult with reactions that lead directly from the gas phase to a solid, dissipate the heat. Particular difficulties arise with the reaction between sulfur trioxide and ammonia, which is highly exothermic and momentary. There is a risk of overheating, which results in the formation of a glass-like melt, which essentially consists only of ammonium sulfate and ammonium im'idodisulfonate consists. This significantly reduces the yield of sulfamic acid.

'Proposals have already been made to remedy these abuses (Japanese patent 7515 (1951)) »the reaction space in many To subdivide individual pipes, but this requires a high level of design effort. The heat is dissipated here through the pipe walls.

According to another proposal (Japanese patent 1029 0952), sulfur trioxide is used in strong dilution with inert gas. A gas mixture is blown that is only about 5 to 15 %

209835/0960 ./.

'HOE 71 / Ρ Ο48

SO “contains gaseous ammonia at high speed. The heat of reaction is partly absorbed by the inert gas and dissipated through the reactor wall.

It has now been found that the disadvantages of the known reaction of sulfur trioxide with ammonia in the gas phase are eliminated can avoid. , if you bring the ammonia at least partially in liquid form into the reaction chamber.

In this case, the heat of reaction is used directly as the heat of evaporation dissipated by the liquid ammonia. In contrast to the pure gas phase process, the temperature Control very precisely the proportion of finely divided liquid ammonia added. In addition, the space-time yield compared to the pure gas phase reaction and even more so compared to carrying out the reaction in the presence of a Inert gas can be increased significantly. Even in a conventional reactor you get when using liquid Ammonia easily doubles the space-time yield compared to the use of gaseous ammonia.

example 1

3 In a given reactor with a volume of 3 »2 m, pro Hour 14.5 kg SO_ and 11.0 kg NH "metered in in gaseous form. There are 20 kg per hour of a reaction mixture of 32 $ ammonium amido sulfonate, 58 $ ammonium imidodisulfonate and 10 $ ammonium sulfate.

Example 2

In the same reactor as in Example 1 were 28.8 kg and 30.0 kg per hour s0_ NH "which was essentially liquid," metered It emerged per hour kO kg of Reaktbnsgemisches of the same composition as in Example 1, ie, the The space-time yield was twice as large.

209835 / 096D

HOE 71 / F 0 ^ 8 - 3 -

120 g of the reaction mixtures from the two examples were hydrolyzed at 60 ° C. with 250 ml of 60% nitric acid each time. The mixture was then cooled to 0 C and the precipitate formed was filtered and washed with 60% strength nitric acid from OC. It was then dried at 50 ° C. In both, about 60 g of sulfamic acid with a content of about 99-5 ° were obtained.

209835/0960

Claims (1)

HOE 71 / F O48 '- 4th - Claim; Process for producing amidostilfonic acid by reaction of sulfur trioxide with ammonia in the gas phase and hydrolyzing the reaction mixture formed with Mineral acid, characterized in that the ammonia is at least partly brought into the reaction chamber in liquid form. 209835/0960