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FCC Catalyst Demetallization
C.H. Bartholomew and J.B. Butt (Editors), Catalyst Deactiuation 1991 01991 Elsevier Science Publishers B.V., Amsterdam
803
FCC CATALYST DEMETALLIZATION FRANK J. ELVIN, VICE PRESIDENT. COASTAL CATALYST TECHNOLOGY, INC., 9 GREENWAY PLAZA, HOUSTON. TX 77046. USA SUMMARY Coastal Eagle Point Oil Company reduced their fresh catalytic cracking catalyst consumption from 15 tons per day (TPD) to 8.5 TPD. This was achieved by recycling their spent catalyst back to their catalytic cracker after it had been demetahed. Product yields and catalyst properties were successfully maintained at this lower rate of catalyst consumption. INTRODUCTION FCC catalyst demetallization has been practiced commercially by ChemCat Corporation in Meraux, Louisiana. for three years. Refineries ship their spent FCC catalyst to the Meraux plant for demetallization. It is then returned to the refinery where the demetallized catalyst is used instead of fresh catalyst. Until March 1989, all tests at refineries were limited to about one month. As the average time a catalyst particle stays in a cat cracker can vary between 10 days and 200 days, depending on the design of the cat cracker. it was felt that one month was not sufficient time to determine the long-term stability of the demetallized catalyst in a commercial cat cracking environment. To determine the stability of denietallized catalyst and to gain an insight into the deactivation mechanism of demetallized catalyst, a four-month test was made at Coastal Eagle Point Oil Company's cat cracker. The data from this four-month test period were compared with a fourmonth period priorto thecat crackerusingdemetallizedcatalyst. and werealsocompared with afourmonth period after the cat cracker had ceased using demetallized catalyst. The data showed that demetallized catalyst was stable in a commercial cat cracker. They also showed that catalyst activity and selectivity could be maintained by recycling demetallized catalyst just as well as when using fresh catalyst. COASTAL EAGLE POINT OIL COMPANY FCC OPERATION Coastal Eagle Point Oil Company operates a 53,000 barrels per day (BPD) Kellogg Model 3 fluid catalytic cracking unit (FCCU) in Westville. New Jersey. This FCCU processes a mixture of gas oil and residue feedstocks with a nickel content of 4 parts per million weight (PPM) and vanadium content of I PPM. These feedstocks originate predominantly from West African and Chinese crudes. The catalyst used at this refinery is AKZO's HR058 IC, which contains a reduced nonframework alumina Rare Earth exchanged ultrastable-Y zeolite. Coastal's production plan during the time period studied, which was July 1989 to July 1990, required the FCCU to make a minimum of 50% vol. cat gasoline. To achieve this when the refinery was not recycling demetallized catalyst required a continual makeup of 15 TPD of fresh catalyst. The refinery used 15 TPD of fresh catalyst between July 1989 and March 1990. which was immediately prior to the DEMET test run. They also used 15 TPD during the period of May 1990 to July 1990. which was the period after the test run. It was necessary for the refinery to maintain a constant catalyst inventory of 450 tons in the cat cracker and as they were adding 15 TPD and losing 3 TPD to their fine particulate collection systems, it was necessary to withdraw 12 TPD of equilibrium catalyst. This catalyst was disposed of to landfill. The equilibrium catalyst contained 2,000 PPM of nickel and450 PPM of vanadium. It had a surface area of about 128 mVgm.
804
FCC CATALYST DEMETALLIZATION Equilibrium Catalyst Properties Graph 1
g
. 01
N
E
3
c 0
LPG Yields (% wt.) Graph 4
140
15 14
130
13
12
120
5
80
$
11
10
9 8
70
7
6
60
5
DEMET Operation Open Symbols
Jul Aug
Sep Ocl Nov M Jan Feb Mar Apr May Jun Jut
DEMET Operation Open Symbals
0.26
Hydrogen Yield (“4, wt.) Graph 5
0.24 0 22 0.20
0.18 016
g .
014 0.12
0 10 0.08 0 06
F* Mar Apr May DEMET Operation: Open Symbols
Jul Aug Sepl Oci Nov Dec Jan
Oo0
P
Jun July
Equilibrium Catalyst Properties Graph 6 140,
Coke and Dry Gas Yields (% wt.) Graph 3
-
I
z
E
& . N
E
z
3 D
I
I
130
120
80
70
0
0
1000
2000
Ni+V (ppm wt)
3000
DEMET Operalion Open Symbols
4000
805
I n the demetallization catalyst test run. the fresh catalyst makeup to the unit was reduced to 8.5 TPD. Ten TPD of equilibrium catalyst were sent to the Meraux plant for demetallization. This catalyst was then returned to the refinery where it was added to the cat cracker along with the fresh catalyst. During the DEMET test run, losses were running at 1.5 TPD total so that it was necessary to withdraw 7 TPD of spent catalyst and dispose ofthis to landfill. The equilibrium catalyst produced during the DEMET test run contained about 2.000 PPM of nickel and about 450 PPM of vanadium and the surface area remained at 128 mVgni. Equilibrium catalyst properties from July 1989 to July I990 are shown on Graph 1. The open symbols on this graph represent theperiod during which the refinery was using acombinationoffresh catalyst and demetallized catalyst. The shaded symbols represent the periods during which the refinery was using fresh catalyst alone. The results show vividly what happens when metals are allowed to build up on the catalyst as they were allowed to in April 1990. The surface area of the catalyst decreased from 128 mYgm to I 19 rn'/gni, and the activity of the catalyst decreased from 68% vol. to 60% vol. The reason that the metals increased on the catalyst during this pcriod of time was that, immediately following the DEMET test run. the catalyst makeup rate was not increased to 15 TPD. It was allowed to remain at 8.5 TPD to determine what would happen if the recycle of demetallized catalyst stopped and the fresh catalysl makeup stayed at 8.5 tons. As can be seen from Graph 1, the nickel plus vanadium content of the catalyst increased and this resulted in a decrease in catalyst activity and also a decrease in catalyst surface. In early April. the catalyst makeup rate was returned to 15 TPD and the surface area increased back to 128 m'/gm and the activity returned to 68% vol. The FCCU yields ofgasoline and slurry. coke and light gas. olefins. and H, before, during and after the demetallization test run are shown in Graphs 2,3,4 and 5. The gasoline yields are corrected to C5-430"Fcut point: the light cycle yields (LCO) are corrected to 430"F-6501'F cut point; and the slurry yield is corrected to 650"F+ cut point. None of the yields varied significantly from the time that the FCCU was using 15 TPD fresh catalyst to the time that it was using 8.5 TPD fresh catalyst with I0 TPD recycled demetallized catalyst. Graph 6 shows the equilibrium catalyst surface area and activity plotted against Ni + V PPM. This graph shows there is no significant difference in the deactivation rate ofthe cquilibrium catalyst when part of the fresh catalyst was replaced with recycled dernetallized catalyst.
803
FCC CATALYST DEMETALLIZATION FRANK J. ELVIN, VICE PRESIDENT. COASTAL CATALYST TECHNOLOGY, INC., 9 GREENWAY PLAZA, HOUSTON. TX 77046. USA SUMMARY Coastal Eagle Point Oil Company reduced their fresh catalytic cracking catalyst consumption from 15 tons per day (TPD) to 8.5 TPD. This was achieved by recycling their spent catalyst back to their catalytic cracker after it had been demetahed. Product yields and catalyst properties were successfully maintained at this lower rate of catalyst consumption. INTRODUCTION FCC catalyst demetallization has been practiced commercially by ChemCat Corporation in Meraux, Louisiana. for three years. Refineries ship their spent FCC catalyst to the Meraux plant for demetallization. It is then returned to the refinery where the demetallized catalyst is used instead of fresh catalyst. Until March 1989, all tests at refineries were limited to about one month. As the average time a catalyst particle stays in a cat cracker can vary between 10 days and 200 days, depending on the design of the cat cracker. it was felt that one month was not sufficient time to determine the long-term stability of the demetallized catalyst in a commercial cat cracking environment. To determine the stability of denietallized catalyst and to gain an insight into the deactivation mechanism of demetallized catalyst, a four-month test was made at Coastal Eagle Point Oil Company's cat cracker. The data from this four-month test period were compared with a fourmonth period priorto thecat crackerusingdemetallizedcatalyst. and werealsocompared with afourmonth period after the cat cracker had ceased using demetallized catalyst. The data showed that demetallized catalyst was stable in a commercial cat cracker. They also showed that catalyst activity and selectivity could be maintained by recycling demetallized catalyst just as well as when using fresh catalyst. COASTAL EAGLE POINT OIL COMPANY FCC OPERATION Coastal Eagle Point Oil Company operates a 53,000 barrels per day (BPD) Kellogg Model 3 fluid catalytic cracking unit (FCCU) in Westville. New Jersey. This FCCU processes a mixture of gas oil and residue feedstocks with a nickel content of 4 parts per million weight (PPM) and vanadium content of I PPM. These feedstocks originate predominantly from West African and Chinese crudes. The catalyst used at this refinery is AKZO's HR058 IC, which contains a reduced nonframework alumina Rare Earth exchanged ultrastable-Y zeolite. Coastal's production plan during the time period studied, which was July 1989 to July 1990, required the FCCU to make a minimum of 50% vol. cat gasoline. To achieve this when the refinery was not recycling demetallized catalyst required a continual makeup of 15 TPD of fresh catalyst. The refinery used 15 TPD of fresh catalyst between July 1989 and March 1990. which was immediately prior to the DEMET test run. They also used 15 TPD during the period of May 1990 to July 1990. which was the period after the test run. It was necessary for the refinery to maintain a constant catalyst inventory of 450 tons in the cat cracker and as they were adding 15 TPD and losing 3 TPD to their fine particulate collection systems, it was necessary to withdraw 12 TPD of equilibrium catalyst. This catalyst was disposed of to landfill. The equilibrium catalyst contained 2,000 PPM of nickel and450 PPM of vanadium. It had a surface area of about 128 mVgm.
804
FCC CATALYST DEMETALLIZATION Equilibrium Catalyst Properties Graph 1
g
. 01
N
E
3
c 0
LPG Yields (% wt.) Graph 4
140
15 14
130
13
12
120
5
80
$
11
10
9 8
70
7
6
60
5
DEMET Operation Open Symbols
Jul Aug
Sep Ocl Nov M Jan Feb Mar Apr May Jun Jut
DEMET Operation Open Symbals
0.26
Hydrogen Yield (“4, wt.) Graph 5
0.24 0 22 0.20
0.18 016
g .
014 0.12
0 10 0.08 0 06
F* Mar Apr May DEMET Operation: Open Symbols
Jul Aug Sepl Oci Nov Dec Jan
Oo0
P
Jun July
Equilibrium Catalyst Properties Graph 6 140,
Coke and Dry Gas Yields (% wt.) Graph 3
-
I
z
E
& . N
E
z
3 D
I
I
130
120
80
70
0
0
1000
2000
Ni+V (ppm wt)
3000
DEMET Operalion Open Symbols
4000
805
I n the demetallization catalyst test run. the fresh catalyst makeup to the unit was reduced to 8.5 TPD. Ten TPD of equilibrium catalyst were sent to the Meraux plant for demetallization. This catalyst was then returned to the refinery where it was added to the cat cracker along with the fresh catalyst. During the DEMET test run, losses were running at 1.5 TPD total so that it was necessary to withdraw 7 TPD of spent catalyst and dispose ofthis to landfill. The equilibrium catalyst produced during the DEMET test run contained about 2.000 PPM of nickel and about 450 PPM of vanadium and the surface area remained at 128 mVgni. Equilibrium catalyst properties from July 1989 to July I990 are shown on Graph 1. The open symbols on this graph represent theperiod during which the refinery was using acombinationoffresh catalyst and demetallized catalyst. The shaded symbols represent the periods during which the refinery was using fresh catalyst alone. The results show vividly what happens when metals are allowed to build up on the catalyst as they were allowed to in April 1990. The surface area of the catalyst decreased from 128 mYgm to I 19 rn'/gni, and the activity of the catalyst decreased from 68% vol. to 60% vol. The reason that the metals increased on the catalyst during this pcriod of time was that, immediately following the DEMET test run. the catalyst makeup rate was not increased to 15 TPD. It was allowed to remain at 8.5 TPD to determine what would happen if the recycle of demetallized catalyst stopped and the fresh catalysl makeup stayed at 8.5 tons. As can be seen from Graph 1, the nickel plus vanadium content of the catalyst increased and this resulted in a decrease in catalyst activity and also a decrease in catalyst surface. In early April. the catalyst makeup rate was returned to 15 TPD and the surface area increased back to 128 m'/gm and the activity returned to 68% vol. The FCCU yields ofgasoline and slurry. coke and light gas. olefins. and H, before, during and after the demetallization test run are shown in Graphs 2,3,4 and 5. The gasoline yields are corrected to C5-430"Fcut point: the light cycle yields (LCO) are corrected to 430"F-6501'F cut point; and the slurry yield is corrected to 650"F+ cut point. None of the yields varied significantly from the time that the FCCU was using 15 TPD fresh catalyst to the time that it was using 8.5 TPD fresh catalyst with I0 TPD recycled demetallized catalyst. Graph 6 shows the equilibrium catalyst surface area and activity plotted against Ni + V PPM. This graph shows there is no significant difference in the deactivation rate ofthe cquilibrium catalyst when part of the fresh catalyst was replaced with recycled dernetallized catalyst.