DE743160C - Process for the catalytic splitting off of water from organic compounds - Google Patents

Description

Process for the catalytic splitting off of water from organic Compounds The catalytic elimination of water from organic .. ganIic compounds is one of the most important catalytic. Chemical industry reactions. as In addition to phosphoric acid, phosphoric acid salts, activated carbon, silica gel mainly aluminum oxide is used in every form. When using aluminum oxide As a dehydrating catalyst, the disadvantages are poor thermal conductivity of the oxide as well as the difficulty of shaping.

In order to circumvent these difficulties, the suggestion was made that merely to the surface of metallic aluminum by chemical treatment in oxide transform (German Patent 486 Here, however, you get an oxide layer of only low adhesive strength. After the one with the Swiss patent specification The process described in 194447 is the surface of metallic aluminum on an electrolytic basis Ways converted into an oxide layer that adheres extremely firmly to the base metal and the Oxydschcht produced in this way is used as a carrier for catalytically active substances.

It has now been shown that electrolytically produced oxide layers as such represent excellent dehydrating catalysts without any addition. In addition to the general advantages of the metallic base, these catalysts have (Shaping, possibility of electrical heating) nor that of easy regeneration; because the electrolytically produced oxide. a solid framework with a large. number represents the smallest pores, occurs during regeneration by heating in an air stream no decrease in activity due to sintering together.

The production of this oxide layer is best done by using aluminum in the form of wire, tape or tube in a sulfuric acid electrolyte with direct current, preferably at temperatures from 20 to 30 °, for so to go minutes. at a Oxidized current density from i to 2 A / dm2. The one so produced catalyst is in the evaporation or. Brought to the sublimadon room of the substance to be decomposed and immediately heated electrically. Not yet in the implementation of the reaction After condensation, decomposed substances can enter a reflux condenser into the evaporation chamber be returned, while the resulting gaseous decomposition products escape.

The particular effectiveness of the catalyst lies in this arrangement The reason for this is that the catalyst is constantly being replaced by the vapors of the still urizer Substance is surrounded, while the decomposition products instantly at great speed are led away from the catalyst, so that they only very briefly with the hot zone are in touch. Of course, savings are also made in heating and a simple, continuously operating process is guaranteed.

The process according to the invention can be used for all with elimination of water running reactions in organic chemistry, especially for the Dehydration from alcohol. However, also the elimination of water associated with condensation reactions can be carried out successfully.

Example 1 3 m aluminum wire 1 mm thick, wound on a winding former, m an electrolyte containing 30% sulfuric acid for 1 hour. oxidized at 25 ° with a current density of 1.5 A / dm2. The catalyst thus prepared is placed in a 1 liter flask equipped with a reflux condenser. In the flask, Zoo cm ' ethyl alcohol is heated to the boil and the catalyst is heated from the outside by supplying electricity. As soon as the wire has reached a temperature of 33o °, ethylene begins to develop. At 400 ° a continuous stream of ethylene escapes at a rate of about 200 cm 3 / min-1. The ethylene has a purity of 95 to 96%. At 500 ° the development becomes so stormy that up to 1 liter of gas per minute is generated. The reaction rate does not noticeably decrease even with increasing dilution of the alcohol, so that the gas can be continued for as long as desired by the inflow of new alcohol.

Example 2 Under the same conditions as in example i Isol> utyl alcohol made to evaporate. At 390 ° a gas flow of Isobutylene (99%) with a speed of 320 cm3 / min. At 476 ° the Speed of gas development - 60, cm3 / min.

Example 3 In the same apparatus, a mixture of aoetaldehyde -or paraldehyde and alcohol evaporated. Through simultaneous condensation and elimination of water you get a gas flow with a speed of less than 100 cm3 / min, which is up to 30% Contains butadiene. Example [In the apparatus described, Methylalkoho.l made to evaporate. At a catalyst temperature of 27o ° d ---- e begins Development of dimethyl ether. At 42o °, 450 cm? Dimethyl ether Developed with a purity of 980'o.

Example 5 6 m of aluminum wire with a thickness of 1 mm are placed on a winding body wound up, w '- oxidized in the example i. This catalyst is described in the Apparatus brought. 100 g of acetic acid are heated to the boil in the flask. At a Catalyst temperature of 36o ° from the acetic acid is due to the dehydrating Action of the catalyst converted into acetone, water and carbon dioxide. It will The cooling water of the reflux condenser is kept at 60 °, so you can use the acetone continuously Distill off the process. At a temperature of 46o °, 90 g of acetic acid are converted 42 g of acetone in one and a half hours, corresponding to a yield of 97% of theory, obtain.

Claims (1)

PATENT CLAIM: Process for splitting off water from more organic compounds with the addition of surface oxidized aluminum as a catalyst at elevated temperature, characterized in that, in a manner known per se, surface oxidized aluminum in the form of wire, strip or tube is electrolytically, chemically oxidized used as a catalyst, which is introduced into the evaporation or sublimation space of the substance to be decomposed and immediately heated electrically. To distinguish the subject matter of the application from the state of the art, the following publication was considered in the granting procedure: German patent specification ...... \ r. 486 597.