DE897698C - Process for the production of carbohydrate hydrogenation products with a high content of oxygenated compounds - Google Patents

Description

Process for the recovery of carbohydrate hydrogenation products with high -Content of oxygen-containing compounds The service life of filled iron contacts, as in the case of carbohydrate hydrogenation, primarily for processing high-carbon Gases, e.g. B. water gas, are used, can be known to be extraordinary increase, if, this Kontalde after their, for example -from appropriate nitrate solutions If the precipitation has taken place, it must be washed out particularly carefully. This washout is supposed to Remaining residues - the alkali compounds used for precipitation (mostly sodium carbonate) or alkali metal compounds formed therefrom by reaction with iron salts, e.g. B. Sodium nitrate, remove as completely as possible. When the mentioned alkali compounds or even one of them remain in contact to a greater extent, if so If the contact is badly washed out, then not only is its reducibility made considerably more difficult, but the contacts also work on the subsequent synthesis unsatisfactory. Their lifespan is strong compared to well-washed out contacts decreased.

The observation has now been made that incompletely washed-out iron contacts, the alkali content of which, calculated as K2 0, based on the existing iron content (Fe), is between 3 and 2o0 / 9, primarily between 5 and 10% alkali, is surprising. d large amounts of oxygen-containing products, for example alcohols, esters, aldehydes. etc., result. Well-washed iron contacts, on the other hand, show a sharp decrease in the formation of oxygen-containing compounds, while partially washed-out iron contacts allow the formation of a relatively high proportion of oxygen-containing compounds.

It is -not possible to wash it out very well in the usual way today Iron contacts through a subsequent addition of alkali compounds on the Ways of impregnation to give properties that are peculiar to the contacts which still partially contain the alkali remaining in the contact precipitation.

During the production of the iron contacts to be used according to the invention. the leaching of the precipitated contact mass is regulated in such a way that the finished contacts contain so much alkali compounds that a conversion to potassium oxide results in 3 to 20% K20 of the iron content present, which in turn is calculated as metallic iron. It is particularly advantageous if the alkali content of the finished contact is 5 to 10% K.0 with this method of calculation.

With some types of iron contact it is useful to remaining alkali compounds by subsequent impregnation even more Incorporate alkali amounts into the contact. This can be in the form of potassium hydroxide, Potassium carbonate, sodium carbonate or other compounds of elements of the left Column of the first row of the periodic table.

The method according to the invention is expedient at a synthesis pressure executed by io atii. One can, but already using the present method at normal atmospheric pressure, larger amounts of oxygen-containing synthesis products obtain. The greatest yields of oxygen-containing compounds result from if the synthesis is above. 2o atii is running.

Due to the high alkali content deT used iron contacts result a so-called poor consumption ratio during the synthesis, as the For example, water gas used as synthesis gas with a hydrogen opposite increased, carbon oxide processing is implemented. To avoid this disadvantage it is advisable to use a synthesis gas when working according to the invention, which is particularly rich in carbon monoxide. This not only makes the theoretical one Possibility to increase the yield per cubic meter of reaction gas created, but beyond that. nor an increased formation of oxygen-containing compounds achieved.

In addition to the usual activators , such as copper, zinc or calcium, the iron cantons used and produced according to the invention can also contain other elements which promote the formation of oxygen-containing products. For this purpose, compounds of vanadium, cerium and tungsten come into consideration, but also other elements or compounds of the fourth to seventh group of the periodic system.

Example Via a contact which contained 100 parts Fe, 5 parts Cu, 10 parts Ca 0, 10 parts kieselguhr and enough alkali to calculate & parts K2 0 , and that by pouring in a boiling solution: the nitrates of the elements mentioned in a boiling solution of soda and subsequent partial leaching, drying, and reduction at 3o, o was prepared ', 1 water gas were passed per liter of contact at io atm hourly ioo. The synbhesis temperature was 2 - #: 2o '. The total product obtained after leaving the oven contained about 30 to 40/9 oxygen-containing compounds, which consisted mainly of alcohols.

If the contact mentioned was subjected to complete washing instead of only partial washing, then the alcohol content of the synthesis products was reduced to about 3 to! 5 1 / o-.

If the last used, completely washed out contact, through a - subsequent - impregnation with potassium carbonate again to a K.0 content of about 8%, the synthesis resulted in about 10 to 151% Yield of oxygen-containing compounds. This was also well below the salary on, oxygen-containing compounds, with the help of the non-washed out contact was attainable.

Claims (2)

PATENT CLAIMS - i. Process for the production of carbohydrate hydrogenation products with a high content of oxygen-containing compounds, characterized in that the carbohydrate hydrogenation is carried out with precipitated iron catalysts which, as a result of incomplete washing, contain 3 to: 2o '/ o, mainly 5 to ioll / o alkali, calculated as K20 , based on the existing iron content (Fe). 2. The method according to claimi, characterized in that the incompletely washed out contacts are additionally impregnated with connec- tions of the left column of the first row of the periodic system, primarily with potassium carbonate or sodium carbonate. 3. The method according to claim i and 2 ", characterized in that the carbohydrate hydrogenation is carried out at a synthesis pressure lying between o and: 2o atü, primarily at -io atü. 4. The method according to claims i and 2, characterized in that that the carbon dioxide hydrogenation is carried out at a pressure above 20 atmospheres. 5. Process according to claims 1 to 4, characterized in that synthesis gases are used which contain more carbon dioxide than hydrogen. 6. Process according to claims 1 to 5, thereby characterized # that the iron contacts used, in addition to the usual activators such as copper, zinc or calcium, contain an addition of elements or compounds from the fourth to seventh groups of the Periodic Table, primarily an addition of vanadium, cerium, tungsten or their compounds. References: German Patent No. 745 444.