DE765512C - Process for the production of iron catalysts for hydrocarbon synthesis - Google Patents

Description

Process for the production of iron catalysts for hydrocarbon synthesis The present invention relates to the production of iron catalysts for Hydrocarbon synthesis; in particular, it relates to the use of compounds of the alkaline earths magnesium, calcium, strontium or barium, which simultaneously act as Precipitants, activators and carriers are used.

For the well-known catalysts for carbon dioxide reduction with iron The effects of additives from compounds are already variously used as the base metal of the alkaline earths mentioned have been described.

The alkaline earths barium, strontium and calcium are used in presented in the literature as unsuitable. The under normal pressure with alkaline earth Iron catalysts achieved activity, measured by the synthesis gas contraction, was about 10 ° / o, so it was extremely small, while one would expect a good iron catalyst with a synthesis gas composition of CO: H2 = 1: 2 at least 30% Must require contraction.

Investigations showed that even small traces of alkaline earths, z. B. the lime content of the water, have a detrimental effect on the contacts. Even no active catalysts were obtained with magnesium, albeit in a single one Case some activation was allegedly observed.

According to the authors, this was one finding despite numerous Attempts do not reproduce, so that one has to assume that the one observed alleged effect must be attributed to other causes.

It is to be regarded as surprising that the invention in contrast the advantageous use of the alkaline earths magnesium, calcium, strontium and barium in the production of iron catalysts of hydrocarbon synthesis.

This is achieved by the precipitation of iron in accordance with the invention with the equivalent or a lesser amount of solid oxides, hydroxides or Magnesium carbonates, calcium, strontium and barium and subsequent precipitation of the alkaline earth metal going into solution takes place through soda as carbonate, with Alkali can be activated.

So here it depends on the precipitating power of the alkaline earth compounds mentioned made use of iron salts, while the previous ones were unsuccessful Try to add alkaline earth compounds, these only dry to the precipitated Irons were added. Due to the subsequent fixation of the alkaline earth as a carbonate in contact this also has the effect of acting as a precipitant Activator and carrier.

This inventive incorporation of the alkaline earth compound in the contact was achieved against all experience that not only did not damage of the catalyst, but a significant improvement in the catalytic properties occurred The type of precipitation with the alkaline earth compounds mentioned has so far been the case eliminated as harmful influence and a catalyst more excellent Let activity arise. The stabilizing effect could now be found in this the alkaline earths have a beneficial effect, for the life of these catalysts is disproportionately larger than that of the previously known.

In addition, the precipitation of the uncertainty becomes too great or too Small amounts of alkali carbonate are released, as these no longer interfere with the precipitation product influence and ensure good filterability in any case. This small one Excess or deficit of alkali carbonate in previous precipitations. z. B. iron nitrate solutions with soda. inevitably led to peptization of the iron hydroxide, which would reduce the filterability extremely adversely affected.

It is known that in unsupported iron catalysts and so far known iron-supported catalysts for the synthesis of hydrocarbons from carbon oxide and hydrogen by increased addition of alkalis both the activity and the Formation of solid paraffin hydrocarbons is increased. The increase in activity However, this has always resulted in a shortening of the life of the catalytic converter due to premature fatigue and therefore no prospect of an economic one Utilization of the advantages given by the increased alkali content (Ges. Dep. Z.

Know of coal, 10, 387 to 392; 1930).

It is also known that by the preferred formation of high molecular weight Paraffins in the unsupported and previously known supported iron catalysts the already existing tendency to clog the contact tubes due to swelling and weathering of the iron catalyst grain is further increased.

It has now surprisingly been shown that the invention Catalysts take advantage of the increased addition of alkali, such as increased activity and preferential paraffin formation, but without premature fatigue in activity or grain changes that can lead to clogging occur. The catalysts of the invention show a more moderate response to increased Alkali addition. d. H. using the same amount of alkali will not give the same increase the activity and the same strong paraffin formation as with the previously known Reached iron catalysts.

The catalysts of the invention require larger amounts of alkali for the equally strong paraffin formation, mainly 2 to 3 times, but without as to show signs of fatigue or grain changes.

The advantage of the catalysts of the invention is accordingly also in the prevention of the paralysis of activity and the grain change at increased Addition of alkali and allows a greater possibility of variation in the amount that occurs liquid and solid hydrocarbons. While the previously known catalysts due to a slightly increased alkali content (1/4 to 1%, based on metallic iron) turn to the side of preferential paraffin formation and premature signs of fatigue demonstrate and grain changes that lead to clogging may suffer from variation the alkali content, based on metallic iron, in the catalysts according to the invention the paraffin formation can be steadily increased while the overall yield remains the same and without premature activity fatigue and without grain changes, d. H. without Danger of clogging of the catalyst chambers.

The mechanical strength of the catalysts is determined by the alkaline earth carbonate content excellently influenced. Brick-hard, very abrasion-resistant pieces are obtained, the can be easily brought to any desired size without creating dust.

Example 1 2 mol of dissolved iron nitrate are mixed with 0.25 mol of barium carbonate and 0.1 mol of copper nitrate and shaken until no more carbonic acid escapes. Then 3.1 mol of soda in solution are added and the mixture is boiled. After washing, 1/8% potassium carbonate, based on iron, is added and dried. yield liquid and slightly condensate Contraction lifespan gaseous carbon in % hydrogen g per 1 cbm CO + H2 at normal pressure CO: H2 = 1: 2 75 3I over 3000 hours at 10 to 15 atm CO: H2 = 1.6: 1 161 50 over 1½ years Example 2 Comparison between a known alkaline earth metal-containing catalyst (a) precipitated from common solution and the catalyst (b) according to the invention. a) I. Catalyst b) a) 1. Catalyst @)% composition% 100 iron 100 100 barium carbonate 100 O, I copper O, I o, 25 alkali 0.25 37.0 iron in the finished catalyst 36.5 a ) 11. Operating conditions b) 60 Applied E'sen, grams 60 24 gas throughput, liter h 24 I, 6: I synthesis gas, CO: H2 1.6: 1 12 operating pressure, atü 12 240 to 250 operating temperature, ° C 240 to 250 a) III. Operating results b) 25 to 10 gas contraction, volume percentage 44 to 50 35 to 10 CO in the tail gas% 50 to 60 70 to 40 liquid and solid products, g / Ncbm CO + H, 120 to I40 a) service life b) after 100 operating hours there was activity and disrupts the contact grain to such an extent that it was extremely powdery for 400 hours and the synthesis was only unchanged. difficult and with restrictions in the reproducibility could be maintained up to the 400th operating hour.

Claims (1)

P A T E N T A N S P R U C H: Process for the production of iron catalysts for the synthesis of hydrocarbons through the reduction of carbon oxide with hydrogen under pressure and at normal pressure, characterized by the precipitation of iron with the equivalent or a lesser amount of solid oxides, hydroxides or Magnesium, calcium, strontium or barium carbonates and subsequent precipitation of the alkaline earth going into solution by soda as carbonate, whereby Ti with alkali can be activated. To differentiate the subject matter of the invention from the prior art are The following publications were considered in the granting procedure: French Patent Nos. 643,784, 660133, 635,950; Journal of the Soc. of chemical industry Japan Supplemental Binding, Vol. 42, 1939, pp. 117 B to 121 B.