VLADIMIR HAENSEL – RESEARCH OF THE KAISER WILHEIM
INSTITUTE AT MULHEIM
V. Haensel. I would like to mention first that research at the Kaiser Wilhelm Institute was not restricted to the Fischer-Tropsch process alone. It involved a great many subjects which have been studied and investigated in this country. These subjects include the following: alkylation using hydrogen fluoride as a catalyst, isomerization of pure hydrocarbons from a standpoint of reaction mechanism and effect of structure of the compound, isomerization of C4 to C8 paraffins (aluminum chloride and hydrogen chloride), isomerization of olefinic hydrocarbons, etc. There was work also on cracking and isomerization of pure hydrocarbons in the presence of aluminum chloride, additional research on methylation and the synthesis of lube oils. So it does indicate a tendency to get away from the Fischer-Tropsch reaction in the direction of what we call here new processes in the petroleum industry. However, returning to the Fischer-Tropsch work by Dr. Pichler using the ruthenium catalyst, the latter being particularly effective in producing high wax yields, it was found that increasing the pressure gives a higher yield of wax and a higher molecular weight of the wax. They have made experiments with pressures as high as 1,000 atmospheres. They also made a two –year life test with this particular catalyst at 100 atmospheres. One of the difficulties with a ruthenium catalyst is that it is very susceptible to sulfur poisoning, much more so than either the cobalt or the nickel catalyst. Apparently, there is no poisoning with one hundredth of a gram of sulfur per 100 cu.m. of gas which is an extremely small amount of sulfur, but poisoning occurs with three tenths of a gram per 100 cu.m. of synthesis gas in a few months.
I believe both Dr. Powell and Mr. Atwell spoke about the various iron catalysts, therefore, I would like to pass over these.
I would like to point out, in particular, that the Germans consider the 100 cobalt: 18 Th02:100 kieselguhr as their best catalyst and new approaches have continuously been made using this particular catalyst. They definitely thought very little of the nickel catalyst and I believe that Martin has the same viewpoint on that catalyst.
We were looking for one specific thing at Kaiser Wilhelm Institute, namely, isosynthesis, and we were actually somewhat disappointed since we thought they were making finished aviation fuels by this process. The work was started in October 1941 and the process involves the reaction of carbon monoxide and hydrogen at 450oC and 300 atmospheres pressure. As catalysts, the following were employed:
(5) Zn0 + Th02 or Ce02 or Zr02
The composition of the charge gas was 1.2 parts carbon monoxide to one part hydrogen. The yields varied from 60 grams to 110 grams of hydrocarbons above C3 plus a small amount of propane. The catch to this matter is that the material they produced by the isosynthesis is not in the liquid gasoline boiling range, but consists primarily of isobutene and a small amount of isopentane. There is still smaller quantity of the C6 to C8 hydrocarbons. The actual alcohol process followed by dehydration and hydrogenation of isobutylene. Small amounts of higher paraffins are formed in the isosynthesis similar to the formation of C5 and higher alcohols and ketones in the isobutyl alcohol process. The C6 fraction formed contains no neohexane. The best catalyst was thoria-alumina catalyst used in equimolar quantities.
Regenerations are required, and as a rule, these are carried out approximately every 45 days. The temperature has a very profound effect upon the reaction: At 400oC alcohols are obtained, at about 425oC dimethyl ether is a product while at 450oC isosynthesis takes place. At 475-500oC aromatics are obtained. Aromatics are also obtained in the same temperature range but at lower pressures. When an temperature of 475oC is used, the regeneration is required every few days. They claim the size of the reaction tube has an effect upon the carbon deposition, 12-15 mm. Tubes can be used satisfactorily, but larger tubes tend to give excessive carbon formation. When we spoke to Martin (Ruhrchemie) about isosynthesis he was under the impression that this process was making 2,2,4-trimethylpentane. Pichler, however, was quite emphatic that it was only isobutene and isopentane being produced. Apparently, as far as I can see, what happened is that originally the Kaiser Wilhelm Institute tried to make Martin believe that this was the method for making isooctane. In other words, they were producing isobutene and isopentane and then a part of this product presumably could be dehydrogenated and the mixture subjected to an alkylation reaction so that eventually isooctane is obtained.
The Kaiser Wilhelm Institute was supposed to have shipped to Ruhrchemie a sample of their isooctane without indicating how many steps it took to obtain this product. At the present time we are reasonably sure that the isosynthesis is a process for making isobutene and isopentane and, of course, there is considerably less interest in the process in this country since isobutene is available in large quantities. The reaction of aromatization is of academic interest only at the present time. It is carried out at 30 atmos. Pressure and 475 to 500oC, the yields from 1 cu.m. of synthesis gas being about 10 grams of liquid which consists of toluene and xylene.
The methylation reaction, as developed by Dr. Koch and his associates is of considerable interest. In one particular case, isobutene is reached with methyl chloride in the presence of aluminum chloride and aluminum metal at about 50-60oC under pressure.
The product obtained consisted of neopentane and methane. In other words, the reaction between two molecules of methyl chloride with one molecule of isobutene gives neopentane and methane and at the same time aluminum metal is converted into aluminum chloride. On the basis of this reaction, isopentane should give 2,3-dimethylbutane and the latter plus methyl chloride should give triptane. These products, however, were not obtained. Evidently, the reaction does not work well above the neopentane range.
I have just received some of the reel indices and, as far as I remember, reels 100-101 cover the work at the Kaiser Wilhelm Institute. I do believe that the above reaction is of interest since it appears to be a limited but definite case of methylation of isoparaffins.
Mr. Atwell discussed the products obtained in the Fischer-Tropsch synthesis and I would like to add that a comparison was made on the relative amounts of 1- and 2-butenes produced with the cobalt catalyst and with the iron catalyst. The ratio of butene-1 to butene-2 with the cobalt catalyst at atmospheric pressure is 0.25, whereas with the iron catalyst at 10 atmospheres pressure, it varies from 0.67 to 1.0. The comparison is not strictly accurate because higher pressures give more of the 1-isomer. They do not have any direct comparison of medium pressure cobalt catalyst with medium pressure iron catalyst which, of course, is the only condition used with the iron catalyst.
A considerable amount of work has been done on the preparation of pure alpha-olefins. This was carried out by the known Ziegler method where the primary chloride is reacted with lithium to make a corresponding lithium alkyl, followed by decomposition of the lithium alkyl at 100oC into the alpha olefin and lithium hydride. The reason for the interest in alpha-olefins lies in their utilization for the synthesis of lube oils.
Mr. Atwell discussed the iron catalyst for the Fischer-Tropsch reaction and I would like to add something about the pretreatment of this catalyst which they believed to have considerable effect upon the activity and the life of the catalyst. The reduction of the catalyst should be done either at sub-atmospheric atmospheric pressure in the presence of either CO alone or water gas or even synthesis gas. The reduction with CO alone results in very active catalysts, however, after it is precipitated there appears to be no effect from exposure to air. The iron catalyst was submitted by KWI to Brabag for competitive tests and, as far as I remember, it came out third. Do you recall that, Mr. Atwell?
H. V. Atwell. I don’t remember. You will find a great disagreement among the Germans themselves as to the proper rating of these tests. Each contestant tried to praise the many factors differently to prove their catalysts was the best. The KWI catalyst gave a good yield of 125 grams per cu. meter of synthesis gas which was the highest of any of those reported. There is one important factor here which is easily overlooked, that is the bulk density of the catalyst varies a great deal in the actual catalysts tested, so the productivity per ton of catalyst would cover quite a wide range.
V. Haensel. In connection with the synthesis products using the iron catalyst, they claim that the olefin content of the product increases with the following items: decrease in the hydrogen content of the synthesis gas, decreasing the pressure of the operation within certain limits, and also the olefin content is increased by increasing above 1% since the catalyst life is considerably alkali, increasing pressure and decreasing temperature. This covers most of the work at the Kaiser Wilhelm Institute, Mr. Chairman.
W. C. Schroeder. Thank you very much Dr. Haensel, before we go into a discussion, I would like to thank Dr. Powell, Mr. Atwell and Dr. Haensel for their very complete discussion of the Fischer-Tropsch process.
D. Gould. Isomerization in this country has largely meant the changing of the structure of paraffin hydrocarbons, particularly for aviation fuel. We had hints in the microfilm reels that the Germans had considerable success in controlling the position of the double bonds in olefins, not only for the low molecular weight hydrocarbons but through the gasoline boiling range. In their studies they found that the shifting of the double bonds toward the center of the molecule increased the octane rating of the fuel. I noticed some of their high-boiling hydrocarbons, perhaps as high as C15, when isomerized by their process gave very considerable yields of isomers, so that the double bond is shifted as many as 4 and 5 places in chain.
C. Haensel. They have done some work on the isomerization of olefins and used as catalysts, cobalt, alumina and phosphoric acid.
W. A. Horne . I would like to say that the Germans in general used HC1 activated clay and alumina for double bond isomerization, which is not done in this country.
V. Haensel. At Ruhrchemie, the Fischer-Tropsch gasoline was treated with this activated clay at atmospheric pressure and a temperature of about 300oC. Under these conditions, there was an increase in the octane number of the product.
W. C. Schroeder. Thank you, Dr. Haensel.
H. V. Atwell. How about putting Mr. Horne on right after lunch so we can get this Fischer-Tropsch story altogether.
W. C. Schroeder. For some reason, Mr. Horne asked to be moved where he is. Is that right?
W. A. Horne. That’s correct.
H. V. Atwell. I was going to talk about the hydrogenation catalyst, and too I thought it would be best to follow the above, but it’s all right with me.
H. H. Storch. Perhaps you could split it up and give us the Fischer-Tropsch now and the hydrogenation later.
W. C. Schroeder. I think we’d better wind up our meeting at a quarter to twelve here, as it will facilitate eating lunch. I think, however, if that’s agreeable with you, can you divide your discussion nicely into two parts? Well then, we will split it up and give you 15 minutes immediately after lunch for your presentation discussion, and another 15 minutes in the regular order.
ADJOURNMENT FOR LUNCH.
W. C. Schroeder. After a brief discussion it was agreed that the authors of reports would put references to microfilms, identifying in the source of information whenever they were working with material taken from the microfilm. At the same time, if they worked with documentary or other material brought over from Europe, sufficient reference should be given into the report so that the source or location of this material could be identified by the sender. I think now, we can go directly with the afternoon session with a little bit of change in the program.
Mr. William A. Horne will now discuss "Catalyst Manufacture for Fischer-Tropsch and Other Processes." There will be approximately 15 minutes for the presentation and discussion of this topic.