Stacked catalyst bed for Fischer-Tropsch
The present invention pertains to a reactor tube comprising a fixed bed of Fischer-Tropsch catalyst particles, wherein the catalyst particles in 5% to 40% of the fixed bed volume at the upstream end have an average outer surface to volume ratio (S/V) in the range of between 3.0 to 4.5 mm −1 , and the catalyst particles in the remaining fixed bed volume have an average outer surface to volume ratio (S/V) in the range of between 4.5 to 8.0 mm −1 , and wherein the difference between the average S/V of the particles at the upstream end and the average S/V of the particles in the remaining fixed bed volume is at least 0.5 mm −1 .
1. A reactor tube comprising a fixed bed of Fischer-Tropsch catalyst particles, wherein the catalyst particles in 5% to 40% of the fixed bed volume at the upstream end have an average outer surface to volume ratio (S/V) in the range of between 3.0 to 4.5 mm−1, and the catalyst particles in the remaining fixed bed volume have an average outer surface to volume ratio (S/V) in the range of between 4.5 to 8.0 mm−1, and wherein the difference between the average S/V of the particles at the upstream end and the average S/V of the particles in the remaining fixed bed volume is at least 0.5 mm−1.
2. The reactor tube according to claim 1 , wherein the catalyst particles in 5% to 40% of the fixed bed volume at the upstream end have an average outer surface to volume ratio (S/V) in the range of between 3.3 to 4.0 mm−1.
3. The reactor tube according to claim 1 , wherein the catalyst particles in the remaining fixed bed volume have an average outer surface to volume ratio (S/V) in the range of between 4.6 to 8.0 mm−1.
4. The reactor tube according to claim 1 , wherein the catalyst particles in the remaining fixed bed volume have an average outer surface to volume ratio (S/V) in the range of between 4.8 to 7.5 mm−1.
5. The reactor tube according to claim 1 , wherein the particles in the remaining fixed bed volume have an effective diameter of at most 2 mm.
6. The reactor tube according to claim 1 , wherein the particles in the remaining fixed bed volume have an effective diameter of at most 1.6 mm.
7. The reactor tube according to claim 1 , wherein the surface area of the catalytically active metal in the upstream end of the fixed bed is lower than in the downstream end.
8. The reactor tube according to claim 1 , wherein the concentration of catalytically active metal in the upstream end of the fixed bed is lower than in the downstream end.
9. The reactor tube according to claim 1 , wherein the dispersion of catalytically active metal in the upstream end of the fixed bed is lower than in the downstream end.
10. The reactor tube according to claim 1 , wherein 5% to 40% of the fixed bed volume at the upstream end shows a full-bed apparent catalytic activity per volume unit which is 30% to 70% lower than the full-bed apparent catalytic activity per volume unit in the remaining fixed bed volume.
11. The reactor tube according to claim 1 , wherein the amount of catalytically active metal per volume unit in 5% to 40% of the fixed bed volume at the upstream end is 30% to 70% lower than the amount of catalytically active metal per volume unit in the remaining fixed bed volume.
12. The reactor tube according to claim 1 , wherein the full-bed apparent catalytic activity per volume unit in 25% to 50% of the fixed bed volume at the downstream end is 1.5 to 3 times higher than the full-bed apparent catalytic activity per volume unit in the remaining fixed bed volume.
13. The reactor tube according to claim 1 , wherein the amount of catalytically active metal per volume unit in 25% to 50% of the fixed bed volume at the downstream end is 1.5 to 3 times higher than the amount of catalytically active metal per volume unit in the remaining fixed bed volume.