DE1667497A1 - Manufacture of chemically pure sulfuric acid - Google Patents

Description

FARBENFABRIKEN BAYER AG

COPY

LE VERKU S E N - Beyerwerk GB / GW. Pttent Department July 15, 196?

- Manufacture of chemically pure sulfuric acid

Pur are the production of chemically pure sulfuric acid various procedures "are known. For example, it was proposed to purify technical acid by fractional distillation. Other processes start from the distillation of oleum or liquid SO, from and mix, the purified sulfuric anhydrite with water vapor in the gas phase, the pure acid being separated off by condensation. Or you lead while cooling the distilled, liquid SO »together with the pure water in 98% sulfuric acid and thus receives one concentrated pure acid, which in further stages to the desired Concentration must be adjusted * Another method is based on removing most of the interfering cations precipitated in dilute acid by hydrogen sulfide and a Excess of the coagulant is oxidized to sulfuric acid.

It has now been found in pure sulfuric acid to a process for the preparation of chemically pure sulfuric acid by absorption of SO ", which is characterized in that SO" -containing gases with oleum treated such that _t maintained over the oleum in approximately the same SO "partial pressure is as in the incoming gas mixture and that the SO »escaping from the oleum is absorbed in chemically pure, about 98-99% sulfuric acid, the above acid concentration being maintained by adding pure water. According to the method according to the invention, it is possible in a simple manner

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very pure sulfuric acid that meets the requirements per analysi. is enough to be produced.

The amount of oleum can be kept very small in relation to the amount of gas and must only be renewed if the Accumulation of the impurities has become so great that the vapor pressures of the same cause a breakthrough.

The following table shows the vapor pressures of SO, above Oleum and the partial pressures of SO ^ in contact gases of various Concentration listed:

Table 1

Oleum, content of
free SO, in $> ρ SO, about oleum at 50 ⁰ C 60 ⁰ C 70 ⁰ C 80 ° C 26.4
30.8
35.1
39.1
43.0 40 ⁰ C 6.0
15.7
38.1
80.6
115.3 13.1
32.1
74.0
144.2
258,? 27.2
63.0
138.2
249.3
425.0 54.1
119.0
1249.2 2.6
7.3
18.8
43.4
64.5

ρ SO, in the contact gas $ 6 55.2 8th # 9 * 10 i 45.6 60.8 68.5 76, c

In the case of contact gases with a content of about 6-10 $> of SO, acceleration temperatures of about 50-70 ° C are preferred.

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is working. As the table shows, it can be used under these conditions produce the desired pure sulfuric acid continuously and with sufficient space-time yields,

The 98-99 # sulfuric acid obtained can be mixed with pure water, preferably with the aid of an inert gas at least diluted to a concentration of 20 - 96 # will.

A possible embodiment is shown on the basis of the schematic drawing of the procedure: through the pipe (l) the .SO ^ -containing gas passed into the washing vessel (2) charged with oleum. Through the pipes (14 and 15) and the pump (16) the oleum can be renewed as required. The gas freed from impurities goes through pipeline (3), drip catcher (4) and pipe (5) into the absorption vessel (6). Via the pipeline (7). the SO ~ -free exhaust gas escapes, Das Absorption vessel (6) contains sulfuric acid from 98 - 99 # HpSO *. This concentration is made possible by pure water that running from the storage vessel (9) via the pipeline (8). The 98-99% acid produced in this way runs through the pipeline (10) into the adjustment system (12), where the dilution is made to the desired concentration. The water required for this runs from the storage vessel (9) via the pipe (11). The finished pure Acid is withdrawn via the pipe (15). The addition of the water, in a known manner by titrimeter systems automatically controlled.

Example ·

In a glass vessel of 20 1 Table of oleum was $ 25> Wi-SJO, presented and gassed with contact gas from a single-stage catalytic furnace with four hordes. The oleum concentration increased

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.tion on $ 35.6> free SO ,. At 58 ^° C., an oleum of this concentration has a vapor pressure of approx. 55 m Hg and this corresponds to the vapor pressure of SO, in a contact gas of 7% . The gas emerging from the oleum, which is in temperature equilibrium, was passed into a glass ball vessel with a capacity of 100 l. The amount of gas was If nr / h. The 100 l vessel contained a sulfuric acid of approx. 99 $> H ₂ SO ^. By

₂ ^

Cooling, a temperature of 35 ~ 38 ⁰ C was maintained. From a supply so much pure water was added to the vessel through a control valve that the acid concentration remained constant within - 0.5 ^. The escaping exhaust gas did not contain any SO. The acid formed in the spherical vessel was passed through a tap into a 20 l glass vessel and there it was adjusted to the commercial concentration of 96 tfo with a further amount of the purest water. Mixing took place by blowing in cleaned compressed air. At the same time, the amount of air ensured sufficient heat dissipation for cooling. The analytical check gave the following values for foreign matter;

Tabel 2 0.001
<0.005
<0.0002
<0.0001 Foreign matter. mg / kg acid iron
arsenic
lead
copper 0.01
<0.5
<0.002
<0.001

The test of the acid according to the regulation "Test of the reagents on purity according to Merk 5 ed. 1959 page 544-546 "resulted in:

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Table 3

Ignition residue. <0.005 1 °

Chloride (as Cl) <0.00006 #

Nitrate (as NO ₃ ) < $ 0.0002

Selenium <0.0003 %

Heavy metals (as lead) < $ 0.0005

Lead . <0.00025 ί>

Iron <0.0001 # '

Ammonium salts (as KH ^) <? 0.0003 ^

Arsenic < $ 0.000003> ■ ·

By KMnO. oxidizable (as 0) <0.0002. #

This shows that pure sulfuric acid can be produced in a technically simple manner using the process described can be used for many purposes, such as reactions with sensitive catalysts, pharmaceutical products, Accumulator filling, among other things, can be used.

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Claims (3)

& T667497 claims% 1. Process for the production of chemically pure sulfuric acid by absorption of SO ^ in pure sulfuric acid, characterized in that gases containing SO ^ are treated with oleum in this way that about the same SO ^ partial pressure over the oleum is maintained as in the incoming gas mixture and that the SO escaping from the qleum, in chemically pure, about 98 - 99 # sulfuric acid is absorbed, whereby through Adding pure water to maintain the above acid concentration will. 2. The method according to claim 1, characterized in that SO ^ -containing gases are used in the catalytic Implementation of SOp-containing gases after intermediate absorption. 3. The method according to claim 1 and 2, characterized in that the obtained 98 - 99 $ strength acid by mixing with pure water with the aid of a stream of inert gas to a concentration of 20 - 96 is diluted i>. In the k 10 875