DE1020613B - Process for the preparation of carbon oxide hydrogenation catalysts - Google Patents

Description

Process for the preparation of carbon oxide hydrogenation catalysts The As is known, carbohydrate hydrogenation can be carried out under normal atmospheric pressure as well as under increased pressure with the help of iron, cobalt or nickel catalysts carry out. When using iron and cobali catalysts, one preferably obtains normally liquid synthesis products. Nickel catalysts are mostly only used technically used when the carbon dioxide and / or carbon dioxide content of gas mixtures should be converted as much as possible into methane.

One has the Kant as a generator used for the hydrogenation of carbohydrates so far in many cases by precipitation from appropriate salt solutions, leaching made of the precipitated mass, deformation and reduction.

The washed out catalyst mass was here both in "thread grain", d. H. in pieces 2 to 3 mm in diameter and 6 to 10 mm in length, as well as in the so-called "Eirich-Korm", d. H. into practically spherical catalyst grains, convicted. Modern countercurrent high-speed mixers are used for the latter shape. z. B. the so-called Eirich mixer, with rotating plates, pan roller and Scraping works (see. Ullmann, Technische Chemie, 2nd edition, Vol. 7, p. 622). In the case of catalyst deformations of this type, up to now the total precipitated has always been found Catalyst mass, d. H. the active metal compounds, activators and an optional added carrier material, further processed together.

It is also known carbon oxide hydrogenation catalysts by decomposition to produce salts that may have been previously applied to carrier materials will. The catalyst metals have also been melted together with aluminum and from the melt products obtained in this way, the aluminum is recovered by alkali detached. In this way, what are known as skeletal catalysts, "z. B. ndRàney nickel catalysts ... In addition to melt catalysts, there are also sintered catalysts known how they z. B. used in the form of iron catalysts for ammonia synthesis but are also suitable for carbohydrate hydrogenation.

For the production of sintered catalysts one mixes, possibly with the addition of water or aqueous solutions, granular or powdered metals or metal oxides, where appropriate activators and carriers are added can. Metals, metal oxides or metal salts serve as activators, while the Carriers, for example from kieselguhr, aluminum oxide, activated bleaching earth or can consist of suitable minerals. Those made from the aforementioned granular substances The mixture produced is first dried and then at 600 to 1400 °, preferably at about 900 to 12,000, sintered. The finished sintered mass is crushed, what to get out of the rungsprodubten sifts out the desired grain size and returns the powdery parts to production. The mixed ones Granular components can also be used before sintering with the help of suitable Mixing devices, for example with the already mentioned Eirich mixer, deformed and only then be sintered. After the deformation, the desired grain size is obtained separated by screening devices and sintered at the specified temperatures.

The undersized grain can be processed into larger grains in the mixer are, while the oversized grain after prior crushing in the manufacturing process returns.

Sintering is often a significant disadvantage. This operation not only causes a considerable increase in the cost of the catalytic material, but also changes the pore structure and the physical structure of the catalyst in mostly undesirable way. Often the sintering of the catalysts even has a reduction the catalyst life and activity result.

It has been found that particularly valuable nickel, iron and Cobalt catalysts result if the metals mentioned and / or their oxides, Activators and optionally carriers are crushed in the form of dust and afterwards more intimately mutual mixing of the required for the desired catalyst composition Quantities with moistening with water or aqueous solutions and with constant agitation in technically customary agglomerating or granulating devices, e.g. B. with help the so-called Eirich mixer, especially in special mixing devices, e.g. B. on turntables, deformed spherically and from the deformed mixture, if necessary after crushing oversized proportions, by screening, classification, Sifting through or similar measures to one another, catalyst grains of approximately the same size separates. This results in a considerable simplification and cheaper of catalyst production.

The new catalyst preparation method has the advantage that despite high activities can be worked extremely cheaply. Compared to Precipitation catalysts are both extensive and costly manufacturing facilities as well as saving expensive starting salts. Compared to sintered catalysts you save the technically expensive sintering process, which is carried out at high temperatures must be and causes a considerable increase in the cost of catalyst production.

The mechanical strength of the catalysts produced according to the invention, in addition to the active components and optionally admixed carriers contain no solidifying additives, is surprisingly much better than the strength of catalysts made by precipitation. Also the activity such catalysts achieve favorable or even excellent values.

As a starting material for the catalysts agglomerated according to the invention it is advisable to use powdered metallic and / or oxidized nickel, Iron or cobalt, preferably nickel and / or nickel oxide. The sole use of oxides is particularly advantageous because in the downstream catalyst reduction the oxides produce particularly active metals. The activity of only from metal oxides produced catalysts is usually best. But also mixtures of oxides and metals up to approximately the same mutual weight ratio still provide Catalysts of satisfactory activity.

The powdery used for the catalyst preparation according to the invention Substances should have a grain size of approximately 0.0001 to 0.050 mm, expediently of about 0.0001 to 0.020 mm, especially from about 0.001 to 0.005 mm. In this case, both in terms of their grain strength and in terms of Their activity obtained particularly good catalysts. Catalyst powder with essential coarser grain, e.g. B. 0.1 mm and above, but give catalysts of inadequate Strength. With the metal oxide and / or metal powders, and although expediently in the same grain size, technically known activators per se, for example copper, silver or alkaline earth compounds are mixed.

These activators are best used in oxidic form, and although appropriate in its highest level of value. For nickel catalysts are Magnesium oxide and magnesium carbonate are particularly suitable as activators, for iron catalysts copper oxide and alkali metal oxides of the alkali metal carbonates are preferably used In some cases it is advantageous to use the powder mixtures to be processed according to the invention still add certain amounts of carrier substances. This can often be done achieve a significant increase in catalyst activity. The admixture of In a surprising manner, the mechanical strength of the catalyst also appears to be the carrier materials to increase. Even relatively small amounts of carrier substances, for example already 10 to 20 percent by weight of kieselguhr, based on the active catalyst metal, can already a substantial solidification of the catalyst grains and a considerable Cause increase in catalyst activity. The optimal amount of admixed The carrier depends on the type of catalyst. With nickel catalysts you can with an addition of 25 to 100 percent by weight of diatomaceous earth, based on the active metal, achieve excellent mechanical strengths and good activities. With iron catalysts Such high additions of carrier material are inexpedient. Here you have to be in general with 5 to 25 if, preferably with about 5 to 150! o carrier material, based on the ferrous metal present, because, in contrast to nickel catalysts, larger ones Carrier quantities cause a decrease in activity. One can do this decrease in activity of the iron catalyst can be compensated for by higher synthesis temperatures. With consideration on the yield of liquid products, the substantial increase in methane formation and the occurring carbon deposition is such in iron catalysts Increase in the synthesis temperature disadvantageous. Cobalt catalysts have in terms of the allowable amounts of carrier material are roughly in the middle between nickel and Iron catalysts.

The inventive preparation of the catalysts can both by prior deformation of the powder mixture to the desired grain size as well as by Comminution of a previously produced lumpy product can be effected. Because the latter If the way you work is relatively cumbersome and expensive, you work appropriately with a previous deformation of the powder mixture. For this purpose, the dry powders of those indicated above consisting of the components in question Grain sizes mechanically or in some other way initially mixed so intimately that color differences of the individual components are practically no longer recognizable.

When shaping the catalytic converters, the fact is exploited that fine powder mixtures turn into spherical structures after moistening by movement let agglomerate. Depending on the particle size and the composition of the powder mixture, this agglomeration takes place after reaching a certain level Moisture content. The water absorption capacity of the processed powder mixtures is to a certain extent dependent on the type of device used for agglomeration addicted. The water absorption capacity and the water content of the wet mixture can depend on the compression of the individual that occurs during the agglomeration Grains fluctuate within certain limits. Depending on the structure and type of used The bulk weight or the so-called knocking weight are also used as agglomerating devices and the grain strength of the finished catalysts to a greater or lesser extent influenced. The diameter of the agglomeration apparatus and the speed or Peripheral speed of a disk used for catalyst production or a container are important.

The grain size of the powder mixture can be determined with the help of technically known Apparatus and methods take place, e.g. B. on turntables, in Eirich mixers or with other suitable agglomerating devices. As an example, below is the Manufacture of the catalysts on a rotating disk described with equipped with a scraper for the continuous division of the dust mixture.

The first batch of the dust mixture is on the rotating disk sprayed with a fine jet of water.

The sprayed liquid can also contain additives in dissolved and suspended form Shape included. The first batch usually produces coarse grains. These will Crushed when moist and passed through a sieve to reduce them to grain sizes to bring, which is usually below the grain size of the final catalyst to be produced lie.

The undersize obtained in this way is used in the ongoing production on The rotating plate is continuously powdered with the newly added dust mixture and rounded off by continuous or intermittent spraying of water or solutions. The desired grain size is achieved with gradual growth. While the production favors the mechanical stress and compression of the aggregated Material ensures an even distribution of moisture within the grain. on In this way, grain hardnesses result, which result in a drying of the catalyst at rest Allow air flow without disintegrating the catalyst granules. The drying of the wet grains is between 80 and 200 °, preferably between 100 and 1500, to carried out to a water content of approximately 00 / o.

Only a small amount of shrinkage occurs here.

The catalysts produced according to the invention are between 150 and 450 °, preferably between approximately 250 and 400 °, reduced in a known manner.

Hydrogen and / or carbon oxide can be used as reducing gases will. In the case of nickel and cobalt catalysts, reduction with hydrogen results the best results. In the case of iron catalysts, both gases can be separated for reduction or used in a mixture of both.

The reduction can be carried out continuously or intermittently, the flow rate of the reducing gases fluctuating within wide limits can.

It is best to use high flow velocities which, for example, Measured linearly and cold, can be at 1 m / second and higher. The reduction can be at atmospheric as well as sub-atmospheric or super-atmospheric Pressure, preferably at normal pressure or overpressure, take place. The reduction of Catalysts can be used either in suitable reduction apparatus or directly be carried out in the catalyst ovens.

The catalysts prepared according to the invention can be used with any Use press to synthesize. The reaction temperatures are expediently between about 150 and 350 °, preferably between about 180 and 280 ". The return some of the residual gases with the addition of fresh synthesis gas, d. H. the so-called Recirculation of the synthesis gases is often advantageous.

Example 1 Preparation of a 1.5 to 3 mm nickel catalyst Grain size A powder mixture was used for the production of this nickel catalyst used, which contained 630% nickel oxide, 7.4% magnesium oxide and 29.6% diatomaceous earth.

The nickel oxide was chemically pure and black in color. Owned it a specific surface area calculated from the Blaine test of approximately 5400 cm2 / g (with regard to the Blaine test, cf. ASTM Standards [1949], Part 3, pp. 103 to 109). That Magnesium oxide was chemically pure and weighed 230 to 300 g per liter. the Kieselguhr was pre-roasted and weighed approximately 98 g per liter.

On a turntable with a diameter of 300 mm, the mixture was the above composition at 87 revolutions per minute within 20 to 40 minutes, preferably within 30 minutes, until clumps begin to form sprayed with water. This state occurred as soon as approximately in the moist mixture 38 per cent. Water was present. The resulting mostly coarse balls were pressed through a sieve of 3 mm mesh size. This resulted in a material mostly from irregular shaped pieces less than 3 mm in diameter and small Lots of damp dust. It was on the turntable under simultaneous Adding a dry powdery mixture and finely divided water rounded off and enlarged.

During production resulted in the manufacture of 1.5 to 3 mm large catalyst grains approximately the following equilibrium state.

On the rotating turntable, 390 g of chips of up to to 3 mm grain size with about 33.70 / 0 water content continuously powdered with dust and within 40 to 60 minutes, preferably within about 47 minutes, sprayed with water. 370 g of dust mixture and 250 g of water were added here.

Both components gave a mixture containing 40.4% water. The total insert was 1010 g. Already during the catalyst molding a certain evaporation of the existing water content took place.

After molding, the moist mixture obtained was initially on a 3 mm mesh screen and then on a 1.5 mm mesh screen treated. This gave 557 g of spherical grains 1.5 to 3 mm in diameter about 33.7% water. In addition, there were 202 g of oversize grain, its grain size was above 3 mm and which was passed through a sieve of 3 mm mesh size, and 188 g undersize, which had a grain size below 1.5 mm. That The oversize grain was combined with the undersize grain, so that a total of 390 g of chips returned to manufacturing. All in all, about 41 0/0 of the wet Use returned as circulation.

The catalyst shaped according to the invention was left idle for 16 hours Dried location at 1200.

This gave a non-glued spherical grain of 1.5 to 3 mm Grain size. As a result of the evaporation of water that occurred during drying a corresponding weight loss and shrinkage of about 50%.

The reduction was also carried out in a resting state.

Hydrogen at 390 "was used for the reduction.

After a reduction time of 90 minutes, a reduction value became achieved by 950/0 nickel. During the reduction, there was a decrease in volume of 50/0 and a weight loss of 180 / o. Before the reduction, that was Catalyst tap weight; d. H. that which occurs when the vessel is gently burped Space filling, to 820 g / 1000 cm3 each.

After the reduction, a tap weight of 710g / 1000 cm3 was achieved. The fully reduced catalyst contained 15 parts by weight per 100 parts by weight of nickel Magnesium oxide (MgO) and 60 parts by weight of diatomite.

4 l of the reduced catalyst were transferred to a reaction tube of 5 m in length and 32 mm inside width. The tube was on its outer surface cooled with water. A gas was passed over the catalyst which, in addition to 33.80 /, Methane and nitrogen 2.50 / o CO2, 5.40 / o CO, 56.30 / 0 H2 and 20/0 heavy hydrocarbons contained (volume percent). The space velocity was 1100, i. h., about 11 of the catalyst were passed hourly 1100 N-liters of gas.

In doing so, both the carbon dioxide present in the transferred gas were removed as well as the liohlenoxyd quantitatively hydrogenated to methane.

Using the same catalyst and the same reaction tube was at a space velocity of 1200 at a pressure of 7 kg / cm2 and a Temperature of 2040 a next to methane and nitrogen 2.5 ° lo CO2, 5.1 0 / o CO and 37.70 / 0 hydrogen (Volume percent) containing gas reacted. Here too the existing carbon dioxide and carbon dioxide were completely hydrogenated to methane.

Example 2 Production of an iron catalyst with a particle size of 2 to 2.5 mm This catalyst was made from a mixture containing 73.20 / 0 iron oxide, 16.20 /, Copper oxide, 5.70 / 0 potash and 4.90 / 0 zinc oxide (percent by weight).

The iron oxide was a purified material containing 66.5 per cent. Fe and 2.60 per cent Contained SiO2. It had a specific surface area determined from the Blaine test of about 18,200 cm2 / g with an average particle size of about 0.0004 mm. The copper oxide was chemically pure and had a particle size of 0.0018 mm or a specific surface area of 11,500 cm2 / g. The zinc oxide had a grain size from 0.0004 to 0.001 mm and a specific surface area of 11 500 cm2 / g. The potassium carbonate was used in chemically pure anhydrous and powdered form.

From the above composite and dry mixture were 400 g in 10 to 20 minutes on the rotating turntable used according to Example 1 so largely sprayed with water that lumps just started to form. This condition was reached as soon as the mixture had taken up approximately 15.4% water. Here Usually coarse balls formed, which were pressed through a sieve with a mesh size of 2.5 mm and on it on the turntable with about the same amount of dust at the same time Sprayed with water. The grain was rounded off and enlarged.

In the production of a 2 to 2.5 mm large grain fraction resulted approximately the following equilibrium during production.

On the rotating turntable, 460 g of chips of less were found than 2.5 mm grain size and continuously powdered with about 12% water content and sprayed with water for about 13 minutes. During this time, 388 g were dry Starting mixture and 70 g of water were added. This amount corresponded to a mixture of dust which contained 15.40 / 0 water. A total of 918 g was fed to the turntable.

After treatment on a sieve of 2.5 mm mesh size and on a sieve with a mesh size of 2 mm remained 322 g of moist spherical grains, one grain size from 2 to 2.5 mm.

With the addition of bits of grain that are released when passing through the oversize particles larger than 2.5 mm through a sieve with a mesh size of 2.5 mm the 332 g of spherical grain increased by 100 g, so that a total of 442 g of moist grain with a water content of 120/0 were obtained. This corresponded to dry matter Amount approximately the amount of the dust mixture used. By one after the deformation Screening carried out was obtained as circulating dust 346 g with a below of 2 mm lying grain size. Also with the sieving downstream of the sieve the result was a fraction with a grain size of less than 2 mm. Overall was there is a circulating amount of moist undersize that is about 51% of the amount used Dry substance corresponded.

With the addition of the grain, the catalyst was not whole as evenly as b i of the preparation according to Example 1. In the tight Sieve limits but in this way an approximately 250/0 increase in the grain yield was achieved.

After one carried out at 120 ° in a resting position for 10 hours After drying, the catalyst had a tap weight of 1670 g per 1000 cm9 of catalyst.

On drying there was a weight loss of about 120 / o, the corresponded roughly to the water content of the moist grain. At the same time there was a decrease in volume of about 30/0 a.

The catalyst was on for 9 hours with flowing hydrogen 320 ° reduced. This resulted in a loss in volume of 0.8% and a loss in weight from 330 / ,. The tap weight of the catalyst was reduced to 1310 g each 1000 cm3. Of the iron oxide present in the catalyst, 91.50 / 0 became metallic Iron reduced. The catalyst then contained approximately iron per 100 parts by weight 25 parts by weight of copper, 8 parts by weight of Ks O and 10 parts by weight of zinc oxide.

In a 5 m long reaction tube with a clearance of about 10 mm 400 cm3 of the catalyst filled.

At a pressure of 20 atm and a temperature of 228 ° was then in a straight pass water gas passed over the catalyst, in addition to methane and Nitrogen contained about 40 per cent carbon dioxide, 4 per cent carbon dioxide, and 500/0 hydrogen (Volume percent).

The space velocity was 400. There was a (CO + H2) conversion of 61.50! o was achieved, which corresponded to a CO turnover of more than 800! 0. The methane formation reached about 9 ° / 0. 32 percent by weight of the liquid products boiled above 320 ".

Example 3 Production of an iron catalyst with a particle size of 2 to 2.5 mm In the same way, as can be seen from Example 2, a dry substance mixture was produced processed, the 74.20 / 0 iron oxide, 16.40 / 0 copper oxide, 5.8 ° lo potassium carbonate and 3.6 ° j0 contained zinc oxide. This mixture was on the rotating turntable with a zinc nitrate solution which contains 175 g of zinc nitrate per liter, d. H. 75 g zinc oxide contained. 185 cm3 of zinc nitrate solution were added to every 1000 g of dry substance mixture bloated. The zinc content of the catalyst was reduced to 10 parts by weight of ZnO increased for every 100 parts by weight of Fe.

This corresponded to its further processing and use Catalyst the values given in Example 2.

Claims (7)

PATENT CLAIMS: 1. Process for the production of carbon oxide hydrogenation catalysts, containing nickel, iron or cobalt, characterized in that the oxides of the metals mentioned and / or these metals, optionally activators and optionally Carriers, dust-like to a grain size of 0.0001 to 0.05 mm, appropriate from 0.0001 to 0.02 mm, crushed and after intimate mutual mixing of the amounts required for the desired catalyst composition with moistening with water or aqueous solutions and with constant movement in the usual technical manner Agglomerating or granulating devices deformed like a sphere and from the deformed Mixture, if necessary after comminution of oversized portions, by sieving, Classification, sifting or similar measures of approximately the same size as one another Separates catalyst grains. 2. The method according to claim 1, characterized in that in the Manufacture of iron catalysts a powder mixture is used, which is less contains more than 250 / o, preferably less than 100 / o, carriers, calculated on the active catalyst metal. 3. The method according to claim 1, characterized in that for production of nickel catalysts powder mixtures are used, which 25 to 100%, preferably Contain 25 to 50 0 / o, carriers, calculated on the active catalyst metal. 4. The method according to claim 1 and 2, characterized in that for Manufacture of iron catalysts during the agglomeration of the powder mixture Water content of at most about 300/0 and at least about 100 / o is set will. 5. The method according to claim 1, characterized in that for production of nickel catalysts in the agglomeration of the powder mixture a water water content of at most about 500 / o and at least about 300/0. 6. The method according to claim 1, 2 and 4, characterized in that one in the production of iron catalysts is that obtained during agglomeration The oversize grain is passed through a sieve or other suitable device Resulting fraction corresponding to the intended useful grain size of the useful grain is added and the underlying undersized grain is returned to the production process. 7. The method according to claim 1, 2 and 5, characterized in that one in the production of nickel catalysts is that obtained during agglomeration Oversized grain is crushed and all of the resulting material is put into the production process returns. Documents considered: German Patent No. 720 575.