DE911848C - Process for the catalytic hydrogenation of carbons with a high yield of oxygen-containing carbon compounds - Google Patents

Description

Process for the catalytic hydrogenation of carbohydrates with a high yield of oxygen-containing carbon compounds. It is known that iron catalysts can be used to prepare preferably oxygen-containing compounds from gases containing carbon and hydrogen at low synthesis temperatures. With a more or less high gas cycle, iron catalysts deliver primary products at around 2oo ', for example, which have approximately 50% oxygen-containing compounds in their liquid components. Synthesis pressures of 10 to 30 kg / sq. Cm, predominantly of approximately 20 kg / sq. The oxygen-containing synthesis products mainly consist of aliphatic alcohols. It has been found that the yield of oxygen-containing products can be increased considerably if one works with a significantly reduced gas load, such that at 150 to 180 ° and gas pressures of 10 to 100 kg / cm 2, preferably from 10 to 30 kg / cm 2 , less than 3o parts by volume, preferably 10 to 20 parts by volume, of fresh synthesis gas (76o mm Hg, 0 °) are passed every hour over one part of the catalyst. The synthesis temperatures used are about 2o to 3o ° lower than the temperatures previously used in the preferred preparation of oxygen-containing caroxide hydrogenation products. Such a far-reaching reduction in temperature is only possible with the gas pollution that is significantly reduced according to the invention; which - only approximately 10 to 20% of today's normal load of 100 parts per hour of synthesis gas per part of catalyst is achieved. The carbon-hydrogen ratio of the synthesis gases can vary within wide limits Part of carbon dioxide, for example, contain 1.2 parts of hydrogen and more. In the synthesis it is expedient to work with the customary recycling of the synthesis gases.

For the process according to the invention, all are in the usual manner Iron catalysts produced by filling are suitable. Are best suited Iron catalysts that have been produced, reduced and formed in a way " are, -as for preferential extraction. of- oxygen-containing compounds already was suggested. It is advantageous here if the catalysts used have the highest possible reduction value and about 50 to 20 o / o free iron (Fe), based on the total iron present. With so largely reduced iron catalysts result in maximum yields of oxygen-containing Compounds: - Iron catalysts with a low reduction value are used in carbohydrate hydrogenation mostly little active and have to achieve economically viable sales levels operated at relatively high temperatures. Here an increased Formation of hydrocarbons and a decrease in primary products containing oxygen a.

The iron catalysts used cannot be used in the synthesis reduced metal oxides and e.g. chromium oxide, zinc oxide, Cerium oxide, manganese oxide, vanadium oxide or molybdenum oxide individually or mutually Mixture included.

Primary products can be used in the procedure according to the invention win, -whose liquid proportions 7o to 8o% oxygen-containing - carbon compounds contain. This not only increases the alcohol content, but also the yield increased in esters, aldehydes and partly also in carboxylic acids.

_ '-. B e i s P. i e I 1 A roo parts Fe, ia parts Cu and io parts Catalyst containing diatomaceous earth was removed at a pH of 9.1. corresponding. Salt solutions like. The precipitation sludge was filtered off with hot condensate water well washed out and then impregnated with potassium carbonate in such a way that on the total iron content (Fe) -approximately 5 0% K2 Ct- accounted for. The impregnated catalyst became more common. Way dried and reduced with hydrogen for 2 hours, - being the flow rate of the reducing gases was 1.3: m / sec (lirieärtund cold _gemesseu). = After the reduction, the catalyst contained 70-0 / b metallic Iron (calculated on the total iron content).

For the production of oxygen-containing synthesis products according to the invention were over this catalyst at i65 ° per hour 10 normal liters of synthesis gas each Liters of catalyst passed. The synthesis gas contained 442 percent by volume CO and 50.8 Volume percent H2. The synthesis pressure was 2okg / sqcm. There was a (C O + H2) conversion of 600 / o achieved. Including those distilled off from the aqueous reaction products The liquid synthesis products contained a total of 75% oxygen compounds oxygen-containing carbon compounds, mainly from alcohols of the - molecular size Passed Cl to C10 and higher. Example 2 From appropriate salt solutions a catalyst produced by precipitation, of 100 parts iron, 10 parts copper, Contained 20 parts zinc oxide, 20 parts chromium oxide and 20 parts diatomaceous earth. The felled Mass was washed out well and so impregnated with potassium carbonate that on 100 parts of its iron content (Fe) accounted for approximately 7 parts of K20. With a linear Flow rates of 1.5 m / sec and 31o ° became the catalyst for 2 hours reduced with hydrogen, whereupon it contained approximately 55% metallic iron (calculated on the total iron content).

This iron catalyst was used for synthesis with an hourly loading of 10 normal liters of water gas (q.0.10 / 0 CO, 50.7% H, 2) per liter of catalyst at a pressure of 20 kg / qcm in a straight gas passage. The synthesis temperature was 167 °. A (CO -f- H2) conversion of 60 0f0 was achieved. Including the oxygen-containing compounds obtained from the water of reaction by distillation, the resulting liquid synthesis product contained 72% oxygen-containing compounds, which consisted predominantly of alcohols - of molecular sizes C1 to C "in addition to smaller amounts of even higher alcohols.

Claims (4)

PATENT CLAIMS: e.g. Process for catalytic I "'- oxyhydrogenation- with high- yield of oxygen-containing carbon compounds. By conversion of carbon oxide and hydrogen-containing gas mixtures over iron catalysts at gas pressures of 10 to 100 kg / qcm, preferably-from 10 to 30 kg / qcm ,. characterized in that at 15o to 18o °, less than 30 parts by volume, preferably 10 to 20 parts by volume, of fresh synthesis gas (76o mm Hg, 0 °) are passed every hour over a space part of the catalyst. 2. The method according to claim i, characterized in; that the iron catalysts used have the highest possible metallic content Own iron, preferably over 5o% metallic iron (based on on the total iron content). 3. The method according to claims i and 2, characterized in that that the iron catalysts with metal oxides which cannot be reducible under the synthesis conditions, preferably with chromium oxide, zinc oxide, cerium oxide, manganese oxide, vanadium oxide, molybdenum oxide or their mutual mixtures, are activated. 4. The method according to claims i to 3, characterized in that synthesis gases which are as rich in hydrogen as possible are used be that on i part of carbon at least 1.2 parts by volume, preferably about 1.5 parts by volume, contain hydrogen. Printed publications: Zeitschrift f. applied chemistry, B 2o, (1948), 225 ff.