DE43453C - Innovation in the process for the preparation of sulfuric acid anhydride - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

CLASS 121; Chemical apparatus and processes. (£ /

Patented in the German Empire on September 13, 1887.

In naphtha production one obtains as a result of the generally accepted procedure the purification of naphtha and its products by sulfuric acid is an immense quantity acidic residues, which up to 90 pCt. contain free sulfuric acid.

These residues are now supposed to represent sulfuric anhydride, fuming sulfuric acid and sulfuric acid monohydrate can be used in the following manner.

The acidic residues are processed into sulfuric acid oxide salts by adding metal oxides, preferably iron oxides, to them. If you add z. B. Ocher (Add a _{small excess of Caput mortuum Fe 2} OJ , a strong reaction occurs; the mixture heats up considerably, and not only the free acid but also the sulfuric acid compounds combine with the ocher.

The resulting mixture of sulphate of iron oxide and resins can be mixed with light Treat naphtha hydrocarbons with all the resins dissolving and the remaining one Salt, after it has been dried, immediately gives rise to sulfuric anhydride etc. can be used.

However, one can also omit the solution of the resins and the mixture obtained of sulphate of iron oxide and resins. after removing the water by heating Bring it directly into an oven and use it to prepare sulfuric anhydride, etc. The resins have no reducing effect on the sulfuric anhydride vapors formed, and no sulphurous acid is released because of the decomposition of the sulphurous metal oxides with the excretion of only a portion of sulphurous acid anhydride at such a low temperature happens that the resins do not volatilize. The resins can be burned out on it and the remaining salt on Use new ones to neutralize the acidic residues.

Of course, you can use this process not only to remove the acidic residues naphtha production, but also those of any other industry.

The procedure is based on the following facts:

ι. When distilling sulfuric acid salts in retorts for the preparation of anhydride if the main obstacle is the high specific gravity of the anhydride vapors, which, after they have excreted from the salts, are immovable over the layer of salt.

2. The heating of a thick layer of salt, which is poorly conductive to heat, is required a great and useless expenditure of fuel.

3. On heating of ferric sulphate, a part Schwefesäureanhydrid separates very easily at a temperature of about 300 to 500 ⁰ C, while the rest requires a significantly higher temperature, wherein a portion of the sulfuric anhydride decomposes into sulfur dioxide and oxygen, wherein the decomposition of other sulfuric acid salts also happens at high temperature.

On the basis of these observations it was concluded that this was successful To prepare anhydride from sulfuric acid salts, it is especially necessary to use the anhydride vapors to be removed from the apparatus in which they have formed, either by artificially blowing air or also by connecting the apparatus to a chimney. You can also, as a Partly anhydride in one case

JIn

Claims (7)

low temperature, replace the costly and inconvenient retorts with a simple oven. In practice one can proceed as follows: 160 parts of ocher (caput mortuum) are poured over with 322 parts of the commercially available sulfuric acid as well as chamber acid in a corresponding amount or a corresponding quantity of acidic residues; by stirring the mixture, the temperature rises to 160 ° C., and a large part of the water is evaporated. The mixture either has to be cooled down or the whole operation has to be carried out slowly, since it starts at about 1500G. the excretion of the anhydride begins. The solid mass obtained (when using sulfuric acid of 66 ° B.) is crushed and, after it has been dried beforehand, placed in the oven, on whose stove it is spread in a thin layer, the temperature in the oven being about 300 may rise up to 5000 C. It goes without saying that when other salts of sulfuric acid are used, the furnace must be kept at the temperature at which the chosen salts decompose. An oven such as that used for the method described. can be used is shown in the accompanying drawing. The hearth A for receiving the salts is spanned by the lowest possible flat vault; the salt is introduced through the door and spread out in a flat layer on the stove. Dried air is blown in through the nozzle b. The anhydride vapors that develop are discharged through the exhaust pipe c under the action of the air flow. If it is a question of the representation of fuming sulfuric acid (H2 SOt + SO3), the anhydride vapors are directed into templates containing sulfuric acid (see Fig. 1); however, if sulfuric anhydride is to be produced in crystal form, the anhydride vapors are passed into cooled templates (see Fig. 2). Instead of blowing air into the furnace, it can also be sucked through the furnace with the aid of a chimney or other device. Here, the suction device is connected to the pipes f or f1 emerging from the last templates. The evacuating fire gases are used to pre-dry the salt. For this purpose an open pan B is placed on the upper surface of the oven, on which the salts are spread in a thin layer, gently heated and dried. The salt must be stirred from time to time as it is decomposing in the oven, gradually moving it from the less heated to the more heated (approx. 300 to 5000 C.) end of the oven, from where the salt is Part of the anhydride that has given off can be removed from the furnace, while fresh salt is brought into the less heated part of the furnace. After a part of the anhydride has been separated out, sulfuric acid or a corresponding quantity of acidic residues is added to the salt remaining in the furnace; the mixture is then predried, as indicated above, until the water has been removed, and then placed again in the oven. There remain z. B. of 400 parts which are put into the furnace, 320 parts back; to these 320 parts 106 parts sulfuric acid or the corresponding quantity of acidic residues are then added and mixed. "The main advantages of the new process are as follows: 1. Inexpensive furnace systems compared to the large number of retorts required up to now; 2. The wear and tear of the furnaces is hardly noteworthy; • 3. rapid removal of the anhydride vapors formed; 4. Enabling continuous operation; 5. Generation of completely anhydrous anhydride; 6. No sulphurous acid is formed in the present process because of the formation of anhydride happens at low temperature. Furthermore, the entire amount of sulfuric acid used is obtained in the form of pure anhydrous anhydride; 7. The consumption of fuel is lower for the reasons given under 6.. Patenτ claim: In the process of preparing sulfuric anhydride in continuous operations from commercially available sulfuric acid or from acidic residues from naphtha production or other industries by mixing the acid or the residues with metal oxides, namely iron oxide, and heating the mixture obtained in a furnace at a temperature of approx. 300 to 500 ^° C., blowing or sucking dry air into or through the decomposition furnace. For this purpose ι sheet of drawings.