DE744076C - Process for the catalytic conversion of gas mixtures containing carbon dioxide and hydrogen into hydrocarbons - Google Patents

Description

Process for the catalytic conversion of carbon monoxide and hydrogen containing gas mixtures in hydrocarbons forms the subject of the invention an improvement in the process of catalytic conversion of carbon dioxide and Hydrogen-containing gas mixtures into aliphatic hydrocarbons using of catalysts consisting of cobalt, hard-to-reducible oxides and carriers, those at atmospheric pressure and temperatures below temperature are more prevalent Methane formation leads to the formation of gasoline, higher-boiling oils and paraffin. This known process is in the magazine fuel chemistry of the years i93off. has been described in detail.

It is then known to use the catalysts with carrier substances, in particular Diatomaceous earth, to be diluted. The optimal amount of diatomaceous earth for synthesis at atmospheric pressure lies according to the information in "fuel chemistry" 12, 228 (1931) and especially 13, 64 (1932) between a metal: kieselguhr ratio of i: i to 2: 3. Considering the lowest bulk density, which in these literature references - for diatomaceous earth is given, the metal content of the finished contact mass is calculated to be approximately 100 g cobalt per liter of contact mass.

It is also known that in the hydrogenation of carbon monoxide to Hydrocarbons also the gas throughput, i. H. so the amount of synthesis gas, the metal active in the catalyst per kilogram per hour in the contact furnace is initiated plays an important role.

The higher the gas throughput, the more methane can be formed suppress. On the other hand, the utilization of the gas becomes less favorable if the gas throughput is increased. In practice, these two phenomena are taken into account by that an optimal gas throughput is maintained, in which on the one hand the methane formation still in acceptable low limits and on the other hand most of the carbon dioxide and hydrogen used are still due to the reaction is implemented. During the synthesis, this optimal gas throughput is below normal Pressure for one liter of synthesis gas per hour per gram of cobalt in the catalyst.

Even with the synthesis under increased bruc4, which initially leads to difficulties came across, wair: ¢ he kept within the same limits. Dagegerk is used in the manufacture of oxygen. containing hydrocarbon compounds by carbon oxyhydrogenation under pressure or in processes that simultaneously contain oxygen-containing hydrocarbon compounds and deliver hydrocarbons, can use much higher gas flow rates. In this case, however, catalysts other than those which are advantageous for gasoline synthesis are used, which, even if they were based on iron or cobalt, are not reduced and in which the metals were essentially in oxide form. Meanwhile delivers this synthesis few hydrocarbons. In particular, with her was the extraction higher-boiling hydrocarbons, such as paraffin, are not possible.

It has now been found that the catalytic conversion of carbon monoxide and hydrogen-containing gas mixtures into aliphatic hydrocarbons with considerable paraffin content at superatmospheric pressure of 2 at or more, e.g. B. io at, can be designed successfully that previously reduced cobalt catalysts, which contain hard-to-reducible oxides and carriers, especially kieselguhr, are used whose metallic cobalt content is over 50 g per liter poured Contact mass is dimensioned, and that the gas throughput is much more than i normal cubic meters metallic cobalt is set per hour and kilogram. For example If the pressure is chosen to be io at, the gas flow rate is expedient according to the invention from what used to be the norm of 1 normal cubic meter per hour to .1 to 8 normal cubic meters increased per kilogram of active metal in the contact mass. Particularly beneficial it is, however, to go further, e.g. B. about up to 2o normal cubic meters, and one To choose an increase in throughput that exceeds the extent of the increase in pressure.

The method according to the invention makes it possible, in particular, good ones To achieve sales with low methane formation. It has also been shown that the service life of the contact is very prolonged and possibly even longer than the service life can be increased when operating under normal pressure.

When working according to the invention, the temperature is under pressure appropriately kept a little higher than when working under normal pressure. "One can however, also at the same temperature or even at lower temperatures get useful results. The yield from working under pressure is wide Limits depend on the amount of gas passed through. You can rely on high yield, for. B. higher yield than it is known at rmaldruck work. This is achieved when using the lower gas scent rates within the limits given above. In this way of working, however, the service life of the contact is not so long, like if you content yourself with the same yield that you get from normal pressure synthesis obtained, or even with lower yields obtained by applying the higher Can achieve gas flow rates. This lower yield can now be accepted take, as they have a lower formation of undesirable by-products, e.g. B. methane, carbonic acid and organic acids, and connected by the invention greatly increased performance of the apparatus is compensated for. You can also get the Working with a high gas throughput a more favorable compound end gas, which without further ado for renewed implementation, possibly after a slight improvement its composition, either in a further contact furnace or on recycling suitable in the same oven.

The new knowledge that led to the invention fits in the observation that one with catalysts, the lower contents of metallic Cobalt contain less than 50 g per liter of poured contact mass, or similar, less effective catalysts compared to the usual ones used under normal pressure Contacts, even under atmospheric pressure, can achieve good yields if the gas throughput is greatly reduced. In practice, however, such a reduction comes with consideration on increasing the burden of debt servicing one with such a low gas throughput working system out of the question. It has been shown to be beneficial with the Process according to the invention not to the highest conversions of the reacting Gas components, but the best products are then obtained, when the gas flow rate and temperature conditions are adjusted so that less implemented as 80% of the carbon oxide and 'or hydrogen contained in the inlet gas will.

Example: One for carrying out the synthesis under normal pressure Well-suited catalyst, consisting of cobalt, thorium oxide and kieselguhr in the ratio i: o, 2. 1.5, which contained 5 g of cobalt in the amount used in a layer 5o cm long in an aluminum tube housed and at a temperature of Zoo ° with 5 liters of a mixture every hour from 300 / a carbon oxide, 6o0% hydrogen and = o0 / 0 nitrogen. The contact worked for days with a constant yield of z05 g of higher-boiling Oils and petrol per normal cubic meter of starting gas. Thereupon the pressure from x was on 5 at and at the same time the gas throughput increased from 5 to 15 normal liters per hour. The reaction temperature was increased so far that the same conversion of carbon dioxide was achieved as previously achieved at normal pressure. In this way of working, the contact between zoo and 115 g of higher-boiling oils and gasoline per normal cubic meter Gases, whereby its performance only declined noticeably after weeks.

Claims (1)

PATENT CLAIM: Process for the catalytic conversion of carbon oxide and hydrogen-containing gas mixtures into aliphatic hydrocarbons at superatmospheric pressure, for example 10 at, using catalysts consisting of cobalt, hard-to-reducible oxides and carriers, in particular kieselguhr, characterized in that previously reduced cobalt catalysts are used whose content of metallic cobalt is measured at over 50 g per liter of poured contact mass, and that the gas throughput is set to significantly more than x normal cubic meters per hour and kilogram of metallic cobalt in the catalyst, expediently with the reaction gases being recycled. To distinguish the subject matter of the application from the state of the art, the following publications were taken into account in the grant procedure: French patents. . . No. 635 g50, 65712q., 66o 133, 788 286; British patent specification. . . . . . . . - 300 29.4; Fuel Chemistry, Vol. 5 (192q.) P. 226, Vol. 7 A926), S. Zoo, Vol. 12 (1931) p. 367 to 36g.