SECTION I(b)
(12) “Static Liquid Phase” Rheinpreussen.
Aside from I.G. Farben the attempt to operate in liquid phase was also made by Rheinpreussen. Their work on liquid phase operation did not leave the laboratory stage. The reaction was studied on a small scale and appeared quite successful. A pilot plant was designed employing a new type of reactor and the unit had been assembled for the most part when the progress of the war stopped further work.
The system employs a slurry of catalyst in the reaction products, the catalyst being held in suspension by the rising bubbles of the feedgas. Contrary to the Michael process the Slurry is here not circulated through a cooler but forms a static layer. The heat of reaction is removed by a cooler consisting of a multitude of tubes hung vertically in the reactor. The details are described in the following section of new reactor design.
The net product of the synthesis boiling within the range of the slurry oil would have to be withdrawn from the reactor and filtered to remove the catalyst. This filtration problem has been the subject of a special study carried out by Rheinpreussen.
The catalyst in these studies was prepared from Luxmasse (the same material as is used for the “Grobreiningung”. The raw mass is thoroughly washed with water and then alkalized with K2CO3. Finally the catalyst is ground in Kogasin to give a fine suspension. The density was around 7 g Fe in 12 liter suspension (3.5% slurry). Here too it was found that the K2O content of the catalyst apparently dropped during operation. It was attempted to correct this by adding K2CO3 in powder form to the slurry, but without success.
After a certain time the catalyst slurry was withdrawn, filtered, and the wax extracted, but this treatment also seemed to have little effect.
Other catalysts, with and without carrier were studied in this system. Carriers appeared to give a lower boiling product, no wax. In one case no liquid buildup was noticed for a period of 670 hours.
Before putting such a unit on stream one of the main problems is the necessity to keep the slurry from settling. it may be necessary to use N2 or CH4 to do so before the synthesis gas is admitted.
The following results were given for operation with slurry catalyst in the laboratory.
| Feedgas | CO=40%; H2=44% |
| Forming of catalyst | (a) Heating slurry (with N2 flowing) to 278° |
| (b) Form with CO containing gas at 250° for 10 hrs. | |
| (c) Put on stream: rate 6 lit/hr feed/10 g Fe. |
|
Conversion |
94% CO |
|
Absorber 60° C |
12 gm/m3 CO+H2 |
|
Light oil 60-280° C |
38 gm/m3 CO+H2 |
|
Heavy oil 280° C |
65 gm/m3 CO+H2 |
|
C3+C4 |
9 gm/m3 CO+H2 |
|
CH4 |
2 gm/m3 CO+H2 |
|
Total |
126 gm/m3 CO+H2 |
This operation appears of great interest and it was regarded as highly promising by the Rheinpreussen engineers.