/.1|ul:_â_ _ u"
Oct. 24, 1961
3,005,771
A. D. BAARS ETAL ISOMERIZATION 0F OLEFINS IN STRIPPING
Filed Jan. 19, 1960
w
_‘A
/______
"_m_T ___ ______
/u.1"|_ul:_“_ __,. _______*______ _________4_ ______
n m W u __ _ a.___ __ __“_"_" _____ H __ a__ _____
INVENTORSI ARIE D. BAARS
WILLIAM THEIR
J. WOLFSON ATTORNEY
tates
latent
1 3,005,771
ISOMEREZATION 0F OLEFINS IN STRIPPING Arie D. Baars and Willem J. Wolfson, Rotterdam, Netherlands, assignors to Shell Oil Company, a corpo ration of Delaware
Z the improvement can be obtained with little or no capital
expenditure and without altering or harming the normal
operation of the catalytic cracking unit by utilizing the
capacity available in the stripping operation. The process of the invention is particularly suitable for the upgrading in BB fractions and PA fractions as men
Filed Jan. 19, 1960, Ser. No. 3,356
tioned above, whenever these fractions contain ole?ns
4 Claims. (Cl. 208-150)
having a terminal double bond in a concentration above that corresponding to the equilibrium. If desired the ma
Claims priority, application Netherlands Feb. 13, 1959 This invention relates to an improvement in petroleum
terial may contain both butylenes and amylenes. It is particularly suitable for the treatment of the BB fractions derived from thermal cracking or reforming treatments. Such fractions generally have a butene-Z plus isobutene to
re?ning Operation through better utilization of ?uid cata lytic cracking units. More speci?cally, it relates to the upgrading of ole?nic C4 and/ or C5 fractions by making butene-l ratio of less than 2. With the use of the process use of existing catalytic cracking stripping capacity. Thus according to the invention it was found possible to in 15 it allows re?nery operations to be improved with little crease this ratio considerably e.g., to values of from 3 to 6 or no capital expenditure. (depending upon the conditions). In addition to the men In modern petroleum re?ning operations catalytic crack tioned isomerization which involves a shift of the position ing plays a most important role since it is responsible for of the double bond, some side reactions occur to a limited the major part of the gasoline produced. Most re?neries extent e.g., isomerization of a carbon skeleton and hy therefore have at least one catalytic cracking unit and 20 drogenation of double bonds by hydrogen transfer. Ac some have several. While there are other types of cata lytic cracking units most of them are so called fluid cata
lytic cracking units in which a powdered silica-alumina containing catalyst is continuously circulated through a
tual losses due to decomposition etc. are however neg
ligibly small. The catalytic cracking ‘operation, as mentioned above,
is carried out for the production of gasoline under the nor reaction zone, a stripping zone, and a regeneration zone. 25 mal conditions. Although these conditions may vary
While gasoline is normally the re?ner’s chief and most important product and the catalytic cracking unit is op erated under conditions to maximize the yield of gasoline of suit-able quality, there are in the usual re?nery small
somewhat due to different feed stocks, ‘activity of the cata lyst, etc. they are all known and need not be further de scribed, except to mention that the temperature in the stripping zone is almost completely a function of the tem 30 streams of other materials of lesser value which should be perature of the catalyst feed to the stripping zone from the utilized as pro?tably as possible. Twosuch materials are reactor and normally lies between about 450 and 540° C. the so called BB (butane-butylene) and PA (pentane As mentioned above a characteristic of the fluidized
amylenes) fractions. These fractions are often quite ole catalytic cracking process is that the catalyst is contin~ ?nic. Those obtained directly from the catalytic cracking uously circulated ‘from the reaction zone through a strip operation contain the various ole?n isomers in approxi 35 ping zone to a regeneration zone and back to the reac' mately the concentrations corresponding to the thermody tion zone. In some units the stripping zone is a partitioned namic equilibrium at the cracking temperature, whereas zone within the reactor vessel. In other units the stripping those derived from thermal operations or from a further is effected in a separate vessel. The catalyst is preferably processing step do not. For example the PA fraction gen stripped while it ?ows in the form of a suspension in the 40 erally contains sizeable amounts of pentenes having a stripping agent through an elongated riser after which branched chain. These are very desirable hydrocarbons it is subsequently stripped in a conventional (dense) ?uid and it is desired to separate them. This is done ‘for in stance by absorbing them in sulfuric acid. This is not
ized bed. Such a riser will usually have a length to the ratio of at least 4 to 1, for example 30 to 1. When the
efficient, however, since the 3-methyl butene-l, although process is applied in this type of an ‘arrangement the mix having a branched structure, contains its ethylenic bond in 45 ture upon leaving the riser is preferably more or less com the terminal position and is not absorbed with the other pletely separated into stripped catalyst, on the one hand, tertiary pentenes. It would be desirable to isomerize the and steam with hydrocarbon vapors on the other and the raf?nate from the sulfuric acid treatment to allow recovery catalyst is then further stripped in the ?uidized state with of this component but this could not be justi?ed econom~ This embodiment, in which the isomerization is ically primarily because of the capital requirements for an 50 steam. carried out in the first stage of stripping and subsequent isomerization unit. stripping is effected in a second stage, is preferred to that A similar situation is found with the BB fraction. This in which the feed to be isomerized is injected into a ?uid fraction is normally used in the production of alkylate. ized catalyst mass which mass is stripped in a single stage However, the quality of the alkylate produced is largly since in the former process the catalyst entering the re in?uenced by the nature of the butylenes. Thus, the F— 55 generation zone has the least possible hydrocarbon con— 44% octane number (the performance number of the tent. In this connection it should be noted when operat material after the addition of 41/2 ml. tetraethyl lead per ing as above described it has been found that the hydro US. gallon) of the alkylate from isobutene and isobutane carbon content of the spent and stripped catalyst which is 152, of the alkylate from isobutane ‘and butene-Z, 155, is led to the regeneration zone is not noticeably affected by and of the alkylate from isobutane and butene-l, 126. 60 the presence in the ?rst stripping zone of the o-le?nic hy From these numbers it would be seen that the BB frac drocarbons added. On the contrary, the injection of the tion going to alkylation preferably contains little butene-l; ole?n fraction makes it often possible to effect an ap in other words, the isobutene plus butene-Z to butene-l preciable reduction in the steam requirements for stripping ratio is preferably as high as possible. It is known that butene-l can be isomerized to butene-Z 65 and this is an economic advantage. The invention will be further described with reference up to limits set by the thermodynamic equilibrium; see for to the accompanying drawing which shows a diagram of a example French Patent No. 913,756. However, here catalytic cracking reactor with a built in stripping zone A again the improvement possible by decreasing the con
separated from the reaction zone B by the partition 1. tion to its equilibrium concentration is entirely insuf? 70 Above the partition the reaction zone and stripping zone are in open communication. The levels in the ?uidized cient to justify an isomerization unit.
tent of butene-l from say twice its equilibrium concentra
It has been found that in either or both of these cases
beds in zones A and B are below the top of the partition 1.
3,005,771
3 In this arrangement the gases and vapors in the stripping
Table II
zone are discharged from the reaction zone together with
the cracked products, that is through line 2. The oil is supplied through line 3 together with the regenerated cata
Starting material
, lyst. Spent catalyst ?ows through line 4 from the reaction zone B to the riser 5 and is passed in the form of a sus
isobutane _______________ __percent by weight“
16. 2
20. 8
n-butane _ _ _ _ _ . _
. _ _ _ _ _ _ _ _ _ _ _ _ __d0.___
44. 9
48. 3
___do-___
12. 6
isobutene. _
___do____
12.6
8. 5
n~butel1e~2_
-_do____
13. 3
16. 2
butadiene__
.... __do____
0. 4
0. 0
———_-_ ratio ____________________ __
2.06
3. 92
pension through the riser by means of steam supplied by way of line 6, stripping already occurring to a substantial
n-butene-1___
extent in the riser.
The catalyst then ?nds its way to the
?uidized bed in zone A. The bed level may be below or 10 butene-2-I-isobutene above the top of the riser 10 but is preferably below. The
catalyst is then ‘further stripped in the ?uidized bed with steam supplied through line 7. The stripped catalyst leaves the stripping zone through line 8 for regeneration in the
regenerator (not shown).
6.3
butane-1
15
According to the invention an ole?n or ole?nic fraction
of C4-C5 hydrocarbons, of which those having a terminal double bond are present in greater than the equilibrium
concentration, is supplied through line 9. 20
EXAMPLE 1
Recovered (Jr-fraction
EXAMPLE 3 In this example the isomerization was effected in a laboratory unit operating on the same principle and in which the C4 fraction was injected into an elongated strip per riser in which a temperature of about 482° C. pre vailed. A butene-2-l-isobutene/butene-1 ratio of 5.55 was
obtained. (Experiment 3.)
In another experiment for comparison the same feed was introduced into the ?uid bed in the stripping zone. Fur
In a commercial unit 23 to 24 tons of spent catalyst were
ther data and the composition of the starting material and riser (length 25 meters, diameter 0.9 meter) in which it 25 the two products obtained in these two experiments are listed in the following Table 3. was stripped with steam. For this purpose 257 tons of steam were used daily when operating catalytic cracking Table 11] passed per minute from the catalytic reactor to a stripper
unit in conventional manner with no ole?n injection. The catalyst was subsequently stripped in a ?uidized bed in a stripping zone with an additional amount of 60 tons per 30 day of steam.
Starting
material
Recovered (Jr-fraction in expet'i-
in experi
ment 3
ment 4
The temperature in the riser was 465-475 ° C. isobutane__.__percent by weight"
In a ?rst experiment according to the invention an
n-butane_
amount of 100 tons a day of an ole?nic C4 fraction was
_.do
_
n-butene-
supplied to the of the stripper riser and the amount of 35 steam supplied was reduced to 215 tons per day. The C4 traction was separated from the gaseous e?iuent. It was
found that there had been practically no loss of C4 hydro carbons. The composition of the starting material and the C4 fractions are shown as following Table I. 40
isobutene
7. 5
11.7
23.7
41.1
45. 7
52.3
18. 5
6. 5
4. 1
_
16. 2
15. 5
9. 2
n-butene-2_ __do-___ butadiene ________________ ._do__-_
15. 5 1. 2
20. 6 0.0
10. 7 O. 0
butene-Z-l-isobutene butene-l
l. 71
5. 55
4. 85
-—~——_— ratio _______ __
We claim as our invention:
1. In the catalytic cracking of a hydrocarbon oil in a ?uid catalytic cracking system with a silica-alumina con
Table I
taining catalyst and wherein the used catalyst is contin Starting material
Recovered
(Jr-fraction 45
uously cycled to a regeneration zone after stripping it of occluded hydrocarbons with steam in a stripping zone,
the improvement which comprises stripping said used cata isobutane _______________ __pereent by weight“
9. 7
10.6
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __do____
52. 0
59. 7
n-butene-l.
___do____
13. 6
6.2
isobutene
___
3,005,771
A. D. BAARS ETAL ISOMERIZATION 0F OLEFINS IN STRIPPING
Filed Jan. 19, 1960
w
_‘A
/______
"_m_T ___ ______
/u.1"|_ul:_“_ __,. _______*______ _________4_ ______
n m W u __ _ a.___ __ __“_"_" _____ H __ a__ _____
INVENTORSI ARIE D. BAARS
WILLIAM THEIR
J. WOLFSON ATTORNEY
tates
latent
1 3,005,771
ISOMEREZATION 0F OLEFINS IN STRIPPING Arie D. Baars and Willem J. Wolfson, Rotterdam, Netherlands, assignors to Shell Oil Company, a corpo ration of Delaware
Z the improvement can be obtained with little or no capital
expenditure and without altering or harming the normal
operation of the catalytic cracking unit by utilizing the
capacity available in the stripping operation. The process of the invention is particularly suitable for the upgrading in BB fractions and PA fractions as men
Filed Jan. 19, 1960, Ser. No. 3,356
tioned above, whenever these fractions contain ole?ns
4 Claims. (Cl. 208-150)
having a terminal double bond in a concentration above that corresponding to the equilibrium. If desired the ma
Claims priority, application Netherlands Feb. 13, 1959 This invention relates to an improvement in petroleum
terial may contain both butylenes and amylenes. It is particularly suitable for the treatment of the BB fractions derived from thermal cracking or reforming treatments. Such fractions generally have a butene-Z plus isobutene to
re?ning Operation through better utilization of ?uid cata lytic cracking units. More speci?cally, it relates to the upgrading of ole?nic C4 and/ or C5 fractions by making butene-l ratio of less than 2. With the use of the process use of existing catalytic cracking stripping capacity. Thus according to the invention it was found possible to in 15 it allows re?nery operations to be improved with little crease this ratio considerably e.g., to values of from 3 to 6 or no capital expenditure. (depending upon the conditions). In addition to the men In modern petroleum re?ning operations catalytic crack tioned isomerization which involves a shift of the position ing plays a most important role since it is responsible for of the double bond, some side reactions occur to a limited the major part of the gasoline produced. Most re?neries extent e.g., isomerization of a carbon skeleton and hy therefore have at least one catalytic cracking unit and 20 drogenation of double bonds by hydrogen transfer. Ac some have several. While there are other types of cata lytic cracking units most of them are so called fluid cata
lytic cracking units in which a powdered silica-alumina containing catalyst is continuously circulated through a
tual losses due to decomposition etc. are however neg
ligibly small. The catalytic cracking ‘operation, as mentioned above,
is carried out for the production of gasoline under the nor reaction zone, a stripping zone, and a regeneration zone. 25 mal conditions. Although these conditions may vary
While gasoline is normally the re?ner’s chief and most important product and the catalytic cracking unit is op erated under conditions to maximize the yield of gasoline of suit-able quality, there are in the usual re?nery small
somewhat due to different feed stocks, ‘activity of the cata lyst, etc. they are all known and need not be further de scribed, except to mention that the temperature in the stripping zone is almost completely a function of the tem 30 streams of other materials of lesser value which should be perature of the catalyst feed to the stripping zone from the utilized as pro?tably as possible. Twosuch materials are reactor and normally lies between about 450 and 540° C. the so called BB (butane-butylene) and PA (pentane As mentioned above a characteristic of the fluidized
amylenes) fractions. These fractions are often quite ole catalytic cracking process is that the catalyst is contin~ ?nic. Those obtained directly from the catalytic cracking uously circulated ‘from the reaction zone through a strip operation contain the various ole?n isomers in approxi 35 ping zone to a regeneration zone and back to the reac' mately the concentrations corresponding to the thermody tion zone. In some units the stripping zone is a partitioned namic equilibrium at the cracking temperature, whereas zone within the reactor vessel. In other units the stripping those derived from thermal operations or from a further is effected in a separate vessel. The catalyst is preferably processing step do not. For example the PA fraction gen stripped while it ?ows in the form of a suspension in the 40 erally contains sizeable amounts of pentenes having a stripping agent through an elongated riser after which branched chain. These are very desirable hydrocarbons it is subsequently stripped in a conventional (dense) ?uid and it is desired to separate them. This is done ‘for in stance by absorbing them in sulfuric acid. This is not
ized bed. Such a riser will usually have a length to the ratio of at least 4 to 1, for example 30 to 1. When the
efficient, however, since the 3-methyl butene-l, although process is applied in this type of an ‘arrangement the mix having a branched structure, contains its ethylenic bond in 45 ture upon leaving the riser is preferably more or less com the terminal position and is not absorbed with the other pletely separated into stripped catalyst, on the one hand, tertiary pentenes. It would be desirable to isomerize the and steam with hydrocarbon vapors on the other and the raf?nate from the sulfuric acid treatment to allow recovery catalyst is then further stripped in the ?uidized state with of this component but this could not be justi?ed econom~ This embodiment, in which the isomerization is ically primarily because of the capital requirements for an 50 steam. carried out in the first stage of stripping and subsequent isomerization unit. stripping is effected in a second stage, is preferred to that A similar situation is found with the BB fraction. This in which the feed to be isomerized is injected into a ?uid fraction is normally used in the production of alkylate. ized catalyst mass which mass is stripped in a single stage However, the quality of the alkylate produced is largly since in the former process the catalyst entering the re in?uenced by the nature of the butylenes. Thus, the F— 55 generation zone has the least possible hydrocarbon con— 44% octane number (the performance number of the tent. In this connection it should be noted when operat material after the addition of 41/2 ml. tetraethyl lead per ing as above described it has been found that the hydro US. gallon) of the alkylate from isobutene and isobutane carbon content of the spent and stripped catalyst which is 152, of the alkylate from isobutane ‘and butene-Z, 155, is led to the regeneration zone is not noticeably affected by and of the alkylate from isobutane and butene-l, 126. 60 the presence in the ?rst stripping zone of the o-le?nic hy From these numbers it would be seen that the BB frac drocarbons added. On the contrary, the injection of the tion going to alkylation preferably contains little butene-l; ole?n fraction makes it often possible to effect an ap in other words, the isobutene plus butene-Z to butene-l preciable reduction in the steam requirements for stripping ratio is preferably as high as possible. It is known that butene-l can be isomerized to butene-Z 65 and this is an economic advantage. The invention will be further described with reference up to limits set by the thermodynamic equilibrium; see for to the accompanying drawing which shows a diagram of a example French Patent No. 913,756. However, here catalytic cracking reactor with a built in stripping zone A again the improvement possible by decreasing the con
separated from the reaction zone B by the partition 1. tion to its equilibrium concentration is entirely insuf? 70 Above the partition the reaction zone and stripping zone are in open communication. The levels in the ?uidized cient to justify an isomerization unit.
tent of butene-l from say twice its equilibrium concentra
It has been found that in either or both of these cases
beds in zones A and B are below the top of the partition 1.
3,005,771
3 In this arrangement the gases and vapors in the stripping
Table II
zone are discharged from the reaction zone together with
the cracked products, that is through line 2. The oil is supplied through line 3 together with the regenerated cata
Starting material
, lyst. Spent catalyst ?ows through line 4 from the reaction zone B to the riser 5 and is passed in the form of a sus
isobutane _______________ __percent by weight“
16. 2
20. 8
n-butane _ _ _ _ _ . _
. _ _ _ _ _ _ _ _ _ _ _ _ __d0.___
44. 9
48. 3
___do-___
12. 6
isobutene. _
___do____
12.6
8. 5
n~butel1e~2_
-_do____
13. 3
16. 2
butadiene__
.... __do____
0. 4
0. 0
———_-_ ratio ____________________ __
2.06
3. 92
pension through the riser by means of steam supplied by way of line 6, stripping already occurring to a substantial
n-butene-1___
extent in the riser.
The catalyst then ?nds its way to the
?uidized bed in zone A. The bed level may be below or 10 butene-2-I-isobutene above the top of the riser 10 but is preferably below. The
catalyst is then ‘further stripped in the ?uidized bed with steam supplied through line 7. The stripped catalyst leaves the stripping zone through line 8 for regeneration in the
regenerator (not shown).
6.3
butane-1
15
According to the invention an ole?n or ole?nic fraction
of C4-C5 hydrocarbons, of which those having a terminal double bond are present in greater than the equilibrium
concentration, is supplied through line 9. 20
EXAMPLE 1
Recovered (Jr-fraction
EXAMPLE 3 In this example the isomerization was effected in a laboratory unit operating on the same principle and in which the C4 fraction was injected into an elongated strip per riser in which a temperature of about 482° C. pre vailed. A butene-2-l-isobutene/butene-1 ratio of 5.55 was
obtained. (Experiment 3.)
In another experiment for comparison the same feed was introduced into the ?uid bed in the stripping zone. Fur
In a commercial unit 23 to 24 tons of spent catalyst were
ther data and the composition of the starting material and riser (length 25 meters, diameter 0.9 meter) in which it 25 the two products obtained in these two experiments are listed in the following Table 3. was stripped with steam. For this purpose 257 tons of steam were used daily when operating catalytic cracking Table 11] passed per minute from the catalytic reactor to a stripper
unit in conventional manner with no ole?n injection. The catalyst was subsequently stripped in a ?uidized bed in a stripping zone with an additional amount of 60 tons per 30 day of steam.
Starting
material
Recovered (Jr-fraction in expet'i-
in experi
ment 3
ment 4
The temperature in the riser was 465-475 ° C. isobutane__.__percent by weight"
In a ?rst experiment according to the invention an
n-butane_
amount of 100 tons a day of an ole?nic C4 fraction was
_.do
_
n-butene-
supplied to the of the stripper riser and the amount of 35 steam supplied was reduced to 215 tons per day. The C4 traction was separated from the gaseous e?iuent. It was
found that there had been practically no loss of C4 hydro carbons. The composition of the starting material and the C4 fractions are shown as following Table I. 40
isobutene
7. 5
11.7
23.7
41.1
45. 7
52.3
18. 5
6. 5
4. 1
_
16. 2
15. 5
9. 2
n-butene-2_ __do-___ butadiene ________________ ._do__-_
15. 5 1. 2
20. 6 0.0
10. 7 O. 0
butene-Z-l-isobutene butene-l
l. 71
5. 55
4. 85
-—~——_— ratio _______ __
We claim as our invention:
1. In the catalytic cracking of a hydrocarbon oil in a ?uid catalytic cracking system with a silica-alumina con
Table I
taining catalyst and wherein the used catalyst is contin Starting material
Recovered
(Jr-fraction 45
uously cycled to a regeneration zone after stripping it of occluded hydrocarbons with steam in a stripping zone,
the improvement which comprises stripping said used cata isobutane _______________ __pereent by weight“
9. 7
10.6
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __do____
52. 0
59. 7
n-butene-l.
___do____
13. 6
6.2
isobutene
___
