SECTION I(b)
(10) “Oilkreislauf” Process- I.G. Farben.
(See reference I(b)/11, I(b)/12, and I(b)/13 at end of this section)
The catalyst used was of the fused iron type (ammonia catalyst). It was obtained by melting pure iron powder (from carbonyl) with O2 and adding certain promoters. The melt was then broken into particles from 8-15 mm. Size and arranged in a reactor as a solid bed. A 500 mm. Chamber, 6 m. high was used in the tests.
The oil used for circulation is the product of the synthesis itself, sp. Gr. 0.8-0.81, conditioned by distillation to keep it within any specified boiling range. The use of the oil prohibits the development of any local hot-=spots and thus lowers the yield of gaseous products.
| The operating results were as follows: | ||
| Pressure |
25 atm. |
|
| Temperature |
300° C (approximately) |
|
| Space velocity |
200 V/H/V (apparent catalyst density 2.5) |
|
| Yield |
150 g.m3 Total product/basis ideal gas |
|
| Conversion |
87% |
|
| Output |
7.2 ton/10 m3 catalyst volume. |
|
|
Product Distribution. |
||
| Gasoline |
40% (50% olefine, 2% oxygen, on65) |
|
| Gas oil |
20% (40% olefine, 0.6-1% oxygen) |
|
| Hard Wax |
20 (95° C melting point) |
|
| C3+C4 |
15 (75% olefine) |
|
| Alcohol |
5% (mostly ethylalcohol) |
|
Olefines boiling above 100° C consisted of 50% normal and 50% isolefine (no data were given for the paraffins).
The most important fact is the high space velocity and resulting high production from a given catalyst volume. It is furthermore a considerably simpler and thus cheaper method, than the customary synthesis.
The cost for a 100,000 ton/year plant was given as RM 5,720,000 (RM 57.2/yearly ton) as compared to RM, 243/yearly ton for the gas circulation process (I.G.) or RM 290/yearly ton for a regular FT plant (Lurgi) with Fe catalyst and “Kreislauf”. This figure appears quite out of line. The difference may be due to the exclusion of certain auxiliary equipment.
The use of the “Oilkreislauf” was later considered for the production of alcohols. In particular alcohols in the C9-C12 range were desired for detergents and chemicals. To this end tests were run with the system at elevated pressures (100 and 180 atm.) but the results were negative since the product was quite low boiling.