Method of producing olefin using circulating fluidized bed process
Disclosed is a method of producing an olefin using a circulating fluidized bed process, including: (a) supplying a hydrocarbon mixture including propane and a dehydrogenation catalyst to a riser which is in a state of a fast fluidization regime, and thus inducing a dehydrogenation reaction; (b) separating an effluent from the dehydrogenation reaction into the catalyst and a propylene mixture; (c) stripping, in which a residual hydrocarbon compound is removed from the catalyst separated in step (b); (d) mixing the catalyst stripped in step (c) with a gas containing oxygen and thus continuously regenerating the catalyst; (e) circulating the catalyst regenerated in step (d) to step (a) and thus resupplying the catalyst to the riser; and (f) cooling, compressing, and separating the propylene mixture, which is a reaction product separated in step (b), and thus producing a propylene product.
1. A method of producing an olefin using a circulating fluidized bed process, comprising:
(a) supplying a hydrocarbon mixture including propane and a dehydrogenation catalyst to a riser which is in a state of a fast fluidization regime, and thus inducing a dehydrogenation reaction;
(b) separating an effluent from the dehydrogenation reaction into the catalyst and a propylene mixture;
(c) stripping, in which a residual hydrocarbon compound is removed from the catalyst separated in step (b);
(d) mixing the catalyst stripped in step (c) with a gas containing oxygen and thus continuously regenerating the catalyst;
(e) circulating the catalyst regenerated in step (d) to step (a) and thus resupplying the catalyst to the riser by adding the catalyst regenerated in step (d) at the bottom of the riser; and
(f) cooling, compressing, and separating the propylene mixture, which is a reaction product separated in step (b), and thus producing a propylene product,
wherein the dehydrogenation catalyst includes: a support including alumina and an auxiliary support component; and a main catalyst including an active metal supported on the support, and includes a promoter including an alkali metal and a Group 6B transition metal.
2. The method of claim 1 , wherein the fast fluidization regime is a fluidization regime in which a dense region is present at a lower portion of the riser and a dilute region is present at an upper portion of the riser, and is a steady state in which a fixed amount of catalyst is continuously introduced into the riser while a gas flow rate in the riser is maintained to be higher than in a turbulent fluidization regime and lower than in a lean-phase fluidization with pneumatic transport regime.
3. The method of claim 2 , wherein, in the fast fluidization regime, a) a gas velocity that is no less than a gas flow rate required for the catalyst continuously introduced through a lower portion of the riser to be entrained and smoothly discharged through an upper portion of the riser is maintained, and b) the gas velocity and a catalyst injection rate are adjusted so that a catalyst volume fraction difference between two points is maintained within a range of 0.02 to 0.04.
4. The method of claim 3 , wherein the catalyst volume fraction difference between a ¼ point and a ¾ point from a bottom of the riser is maintained within a range of 0.02 to 0.04.
5. The method of claim 1 , wherein the hydrocarbon mixture includes propane in an amount of 90% by weight or more.
6. The method of claim 1 , wherein an average size of the catalyst is in a range of 20 to 200 microns.
7. The method of claim 6 , wherein the average size of the catalyst is in a range of 60 to 120 microns.
8. The method of claim 1 , wherein a temperature of a lower portion of the riser is in a range of 500 to 650° C., a temperature of an upper portion of the riser is in a range of 450 to 600° C., and the temperature of the lower portion of the riser is maintained to be higher than the temperature of the upper portion of the riser.
9. The method of claim 1 , wherein a pressure in the riser is in a range of −1 to 5 kg/cm 2 ·g.
10. The method of claim 1 , wherein a residence time of the hydrocarbon mixture in the riser is in a range of 0.1 to 500 seconds for the dehydrogenation reaction to occur in the riser.
11. The method of claim 10 , wherein the residence time is in a range of 0.1 to 50 seconds.
12. The method of claim 11 , wherein the residence time is in a range of 0.5 to 5 seconds.
13. The method of claim 1 , wherein a weight ratio obtained by dividing a weight of the catalyst resupplied to a lower portion of the riser in step (e) by a weight of the hydrocarbon mixture is in a range of 10 to 100.
14. The method of claim 13 , wherein the weight ratio is in a range of 20 to 60.
15. The method of claim 1 , wherein the auxiliary support component includes one or more selected from among zirconium and phosphorus (P).
16. The method of claim 1 , wherein the auxiliary support component is zirconium, and a molar ratio of the zirconium to aluminum (i.e., Zr:Al) in the alumina is in a range of 0.01 to 0.1.
17. The method of claim 1 , wherein a component of the active metal includes one or more selected from chromium, vanadium, manganese, iron, cobalt, molybdenum, copper, zinc, cerium, and nickel.
18. The method of claim 1 , wherein a component of the active metal is chromium, and the chromium accounts for 1 to 20% of a weight of the catalyst.
19. The method of claim 1 , wherein the alkali metal is sodium.
20. The method of claim 1 , wherein the Group 6B transition metal is tungsten.
21. The method of claim 1 , wherein the promoter is included in an amount of 0.01% by weight or more and less than 1% by weight.
22. The method of claim 1 , the alumina support has a γ or θ phase and a surface area of 80 to 300 m 2 /g in a producing temperature range of 550 to 850° C., which is greater than or equal to the dehydrogenation reaction temperature.
23. The method of claim 1 , wherein the dehydrogenation catalyst is produced by a method including:
providing a support including an auxiliary support component and alumina;
allowing a main catalyst including an active metal to be supported; and
drying and calcining the support on which the main catalyst is supported,
wherein a promoter is additionally supported, and the dehydrogenation catalyst is produced by mixing (a) the promoter including an alkali metal and a Group 6B transition metal, and (b) the main catalyst with the support at the same time, or by impregnating the promoter into the support immediately after the drying and then performing drying and calcining, or by impregnating the promoter into the support immediately after the calcining and then performing drying and calcining.
24. The method of claim 23 , wherein the drying is performed at a temperature of 100 to 150° C.
25. The method of claim 23 , wherein the calcining is performed at a temperature of 700 to 850° C.
26. The method of claim 1 , wherein
the auxiliary support component includes one or more selected from among zirconium and phosphorus (P);
a component of the active metal includes one or more selected from chromium, vanadium, manganese, iron, cobalt, molybdenum, copper, zinc, cerium, and nickel;
the alkali metal is sodium; and
the Group 6B transition metal is tungsten.