Process for converting hydrocarbon

Hydrocarbon is catalytically converted by using a fluorine compound represented by the general formula Z.sup.+ MF.sub.6.sup.-, wherein Z is a hydrogen atom or a hydrogen group, and M is a niobium atom, an antimony atom or a tantalum atom as a catalyst, wherein a catalytically inactive component is settled as a heavy liquid phase or deposited as a solid in a reaction product solution from the conversion of hydrocarbon, the heavy liquid phase or the solid is removed from the reaction product solution, thereby removing substantially the catalytically inactive component therefrom, and the remaining catalytically active component is reused in the conversion of hydrocarbon. An amount of a fresh catalyst solution to be supplemented is considerably reduced by effectively reusing the catalytically active component.

This invention relates to a process for converting hydrocarbon by reuse of 
a purified catalyst, and more particularly to a process for converting 
hydrocarbon by using a catalyst of Z.sup.+ MF.sub.6.sup.- system, where 
the catalyst of high activity isolated from catalytically inactive 
component of lowered activity is reused in the conversion of hydrocarbon. 
A catalyst of hexafluoroantimonic acid system represented by the formula 
Z.sup.+ SbF.sub.6.sup.- is typical of the catalyst of Z.sup.+ 
MF.sub.6.sup.- used in the conversion of hydrocarbon, and is well known as 
a Friedel-Crafts type catalyst having a high activity, and a solution of 
the catalyst dissolved in a diluent such as hydrogen fluoride, 
fluorosulfuric acid or sulfur dioxide is usually used as a catalyst 
liquid. Isomerization reaction of, for example, n-paraffin can be 
advantageously carried out at a lower temperature favorable for the 
production of isoparaffins by use of the catalyst of hexafluoroantimonic 
acid system. For example, the catalyst is well known as a particularly 
good catalyst for producing high octane number gasoline by isomerization 
of straight run light naphtha. However, though the catalyst of 
hexafluoroantimonic acid system has such a distinguished property, it has 
not been used yet in an industrial-scale production. One reason is that 
the catalyst of hexafluoroantimonic acid system itself is so corrosive 
that an expensive material of high quality, such as a high 
nickel-molybdenum alloy, etc. must be employed in a reactor apparatus. 
Another essential reason is that only catalytically inactive component of 
the catalyst formed during the reaction cannot be removed from a reaction 
product solution which includes a reaction solution in the course of 
reaction or a catalyst liquid after the use of catalyst, and thus a 
mixture of the catalytically active component and the catalytically 
inactive component must be taken out from the reaction system and a fresh 
catalyst liquid in an amount corresponding thereto must be supplemented to 
renew the activity of the catalyst liquid. A large amount of the 
catalytically active component is, however, taken out together with the 
catalytically inactive component at the same time, and furthermore the 
fresh catalyst liquid to be supplemented must be in excess only by such an 
amount as to correspond to the amount of the taken-out catalytically 
active component. That is, if only the catalytically inactive component 
can be removed from the reaction product solution or catalyst liquid after 
the use of catalyst, the catalytically active component in the reaction 
product solution or the catalyst liquid can be effectively reused without 
being taken out together with the catalytically inactive component, and 
consequently only a smaller amount of the fresh catalyst liquid will be 
supplemented. 
An object of the present invention is to provide a process for converting 
hydrocarbon by removing substantially a catalytically inactive component 
from a catalyst liquid containing both catalytically active component and 
catalytically inactive component after the use of catalyst, or a mixture 
of the catalyst liquid with hydrocarbon, and reusing the catalytically 
active component effectively, thereby reducing an amount of fresh catalyst 
to be supplemented. 
As a result of extensive studies of removing the catalytically inactive 
component from the catalyst liquid after the use of catalyst for many 
years, the present inventors have found that the resulting catalytically 
inactive component is a heavy liquid in a sludge state having a relatively 
high specific gravity or crystalline material, and is different in 
behavior from the catalytically active component, and can readily undergo 
separation and deposition at such a relatively high temperature that the 
catalytically active component cannot undergo separation and deposition, 
and the remaining catalytically active component of high activity can be 
reused, and the present invention is based on such finding. 
That is, the present invention provides a process for converting 
hydrocarbon by using a fluorine compound represented by the general 
formula Z.sup.+ MF.sub.6.sup.-, wherein Z is a hydrogen atom or a 
hydrocarbon group, and M is a niobium atom, antimony atom or tantalum 
atom, as a catalyst, characterized by settling or depositing a 
catalytically inactive component as a heavy liquid phase or a solid in a 
reaction product solution from the conversion of hydrocarbon, removing the 
heavy liquid phase or the solid from the reaction product solution, 
thereby removing substantially the catalytically inactive component 
therefrom, and reusing the remaining catalytically active component in the 
conversion of hydrocarbon. 
The raw material hydrocarbon to be converted according to the present 
invention is not particularly limited, but straight chain or branched 
paraffinic hydrocarbons having 1 to 8 carbon atoms and/or straight chain 
or branched naphthenic hydrocarbons having 3 to 8 carbon atoms are 
practically used. Practically preferable hydrocarbons are paraffinic 
hydrocarbons having 4 to 6 carbon atoms and/or naphthenic hydrocarbons 
having 4 to 8 carbon atoms. Typical paraffinic hydrocarbons include 
n-butane, isobutane, n-pentane, isopentane, n-hexane, and isohexane, and 
typical naphthenic hydrocarbons include cyclohexane, methylcyclopentane, 
methylcyclohexane, dimethylcyclohexane, ethylcyclopentane and 
ethylcyclohexane, and they can be used alone or in mixture. The ordinary 
raw material often used is in mixture. 
The conversion according to the present invention is not particularly 
limited, but is usually directed mainly to isomerization, but can include 
polymerization, dehydrogenation, hydrogenation, etc. in addition to the 
isomerization. 
Practically particularly preferable conversion of hydrocarbon is an 
isomerization of n-paraffins having 4 to 6 carbon atoms. 
The catalyst according to the present invention is a catalyst represented 
by the general formula Z.sup.+ MF.sub.6.sup.- wherein Z is a hydrogen atom 
or a hydrocarbon group, and M is a niobium atom, antimony atom or tantalum 
atom. The catalyst of hexafluoroantimonic acid system is practically most 
preferable among them. 
The hydrocarbon group in said general formula is hydrocarbon groups 
originating from the raw material paraffinic hydrocarbons and naphthenic 
hydrocarbons, and includes, for example, an isobutyl group 
##STR1## 
a methylcyclopentyl group 
##STR2## 
and an isopentyl group 
##STR3## 
Typical catalysts are, for example, H.sup.+ SbF.sub.6.sup.-, 
##STR4## 
H.sup.+ NbF.sub.6.sup.-, 
##STR5## 
H.sup.+ TaF.sub.6.sup.-, and 
##STR6## 
and for example, hexafluoroantimonic acid is a proton type catalyst 
H.sup.+ SbF.sub.6.sup.-, but the proton type catalyst is partially changed 
to a hydrocarbon type catalyst, (hydrocarbon group).sup.+ SbF.sub.6.sup.-, 
through reaction of it with the raw material paraffinic hydrocarbons and 
naphthenic hydrocarbons during the conversion reaction. The hydrocarbon 
type catalyst whose hydrocarbon group originates from the raw material 
naphthenic hydrocarbon has a higher catalytic stability than the 
hydrocarbon type catalyst whose hydrocarbon group originates from the raw 
material paraffinic hydrocarbon, and thus a coexistence of even a small 
amount of the former hydrocarbon type catalyst is preferable. Even if only 
a proton type catalyst is supplied to a reactor as a catalyst, a portion 
of the catalyst is changed to the hydrocarbon type catalyst during the 
conversion reaction, and consequently there is a mixture of the proton 
type catalyst and the hydrocarbon type catalyst in the conversion reaction 
system. 
A catalytic activity "A" is used as an index showing activities of a 
catalyst liquid, a catalytically active component and a catalytically 
inactive component, obtained from actual isomerization of n-hexane using 
these catalyst liquid, catalytically active component and catalytically 
inactive component. That is, "A" is given by the following equation: 
##EQU1## 
wherein: A: catalytic activity (grams of raw material/gram of component 
metal.times.minute) 
L: weight of raw material hydrocarbon containing n-hexane (gram) 
M: weight of component metal (for example, Sb) in catalyst liquid (gram) 
t: effective contact time (time from the start of stirring to separation 
into two layers made by discontinuation of stirring, minutes) 
N.sub.o : initial concentration of n-hexane in raw material hydrocarbon (% 
by weight) 
N.sub.t : concentration of n-hexane in hydrocarbon layer after the 
effective contact time of t minutes (% by weight) 
N.sub.eq : equilibrium concentration of n-hexane in hydrocarbon layer (% by 
weight) 
According to this expression for the catalyst activity, a fresh catalyst 
liquid at such a concentration as usually used has a catalytic activity of 
about 0.50 to about 0.55 at 25.degree. C. 
The present invention is applied to a catalyst liquid of lowered activity, 
and the degree of lowering in the activity is not particularly limited, 
but in view of the economy and easy removal of the catalytically inactive 
component, the present invention is preferably applied to the catalytic 
liquid having a catalytic activity of not more than 90%, particularly 
preferably 20 to 80%, of the catalytic activity of a fresh catalyst 
liquid. 
In the present invention, the reaction product solution obtained by the 
conversion of hydrocarbon is separated into a hydrocarbon layer and a 
catalyst layer. That is, the reaction product solution can be separated 
into two layers by leaving it standing at room temperature for a few 
seconds to about one minute particularly without any heating or cooling, 
but sometimes the separation can require about a few hours. In such case, 
the required time can be shortened by centrifuge, etc. Among the two 
layers, the light liquid phase is a hydrocarbon layer, and the heavy 
liquid phase is a catalyst layer. 
To facilitate the successive treatment and operation, the hydrocarbon layer 
is removed by the ordinary liquid-liquid separation means such as 
decantation, etc. to retain the catalyst layer. The catalyst layer mainly 
contains physically dissolved hydrocarbon, hydrogen fluoride as the 
diluent, catalytically active component and catalytically inactive 
component. The concentration of component metal, for example, antimony, in 
the catalyst layer is usually adjusted to 5-40% by weight, preferably 
19-35% by weight. If the concentration of component metal is less than 5% 
by weight, the catalytically inactive component will not be settled as a 
heavy liquid phase or deposited as a solid in the catalyst layer, whereas 
if it exceeds 40% by weight there will be such an increased danger that 
the entire catalyst layer will be changed into a gel. In both cases, the 
removal of the catalytically inactive component becomes ultimately 
difficult or impossible. If the concentration of component metal in the 
catalyst layer is less than 5% by weight, it is necessary to concentrate 
the catalyst layer, but the temperature for concentration must be not more 
than 100.degree. C., because, if the temperature is above 100.degree. C., 
the activity of catalytically active component will be lowered during the 
concentrating operation. Concentration is carried out by any of such means 
as (A) stripping by passage of an inert gas such as nitrogen gas, hydrogen 
gas or helium gas (B) concentration under a subatmospheric pressure, (C) 
concentration by heating under a subatmospheric pressure, and (D) 
concentration by heating. The means (A) is usually carried out at room 
temperature, but the simultaneous heating is not objectionable. The means 
(B) is usually carried out at -10.degree. to 25.degree. C., the means (C) 
usually at 25.degree. to 50.degree. C., and the means (D) usually at 
25.degree. to 100.degree. C. Among these means, the means (A) to (C) are 
preferable because the catalyst layer is not exposed to a high 
temperature. 
By keeping the catalyst layer of the specific concentration at -120.degree. 
to 50.degree. C., preferably -100.degree. to 20.degree. C., settlement of 
a heavy liquid phase or deposition of a solid takes place. If the 
temperature is below -120.degree. C., there is an increased danger that 
the entire catalyst layer is changed into a gel, whereas, if the 
temperature is above 50.degree. C., neither heavy liquid phase is formed 
nor solid is deposited. In both cases, the removal of the catalytically 
inactive component becomes very difficult or impossible. 
The state of separation between the catalytically active component and the 
catalytically inactive component in the catalyst layer further mainly 
includes the following three states (a) to (c) in addition to said state. 
That is, the state (a) is such that the catalyst layer is separated into a 
light liquid phase and a relatively small amount of a heavy liquid phase 
in a sludge or tarry state. The light liquid phase can be obtained from 
the catalyst layer separated by the ordinary liquid-liquid separating 
means such as decantation, etc., and mainly contains both catalytically 
active component and catalytically inactive component, whereas the 
remaining heavy liquid phase mainly contains the catalytically inactive 
component. By further keeping the light liquid phase at -120.degree. to 
30.degree. C., preferably -80.degree. to 20.degree. C., a solid will be 
deposited. The catalytically inactive component is mainly contained in the 
solid, whereas the catalytically active component is contained in a liquid 
phase. The heavy liquid phase in the sludge or tarry state is sent to a 
waste catalyst treatment step or regeneration step. 
The light liquid phase after removing the solid by the ordinary 
solid-liquid separation means is returned to the reaction system as it is, 
or after being supplemented with the fresh catalyst liquid, whereas the 
solid is sent to the waste catalyst treatment step or regeneration step as 
it is, or after being subjected to repetitions of recrystallization in 
such a diluent as the above-mentioned hydrogen fluoride, etc. as a 
recrystallization solvent to enhance the content of the catalytically 
inactive component whereas mother liquor in the crystallization is 
supplemented with the fresh catalyst liquid and then is sent to reaction 
system. The amount of the recrystallization solvent to be used in the 
recrystallization, such as hydrogen fluoride, etc. is 0.1 to 2 parts by 
weight, preferably 0.2 to 1 part by weight per one part by weight of the 
solid. At the recrystallization, the temperature is kept at -120.degree. 
to 30.degree. C., preferably -80.degree. to 20.degree. C. 
The state (b) is such that the catalyst layer separates into a light liquid 
phase and a relatively large amount of a heavy liquid phase. The light 
liquid phase is removed from the catalyst layer by the ordinary 
liquid-liquid separating means such as decantation, etc., and mainly 
contains the catalytically active component, and can be returned to the 
reaction system as it is, or after being supplemented with the fresh 
catalyst liquid. By keeping the heavy liquid phase at -120.degree. to 
30.degree. C., preferably -80.degree. to 20.degree. C., a solid begins to 
deposit. Then, the heavy liquid phase is separated into a mother liquor 
and the solid by the ordinary solid-liquid separating means such as 
centrifuge, filtration, etc. The mother liquor mainly contains the 
catalytically active component, and is returned to the reaction system 
after being supplemented with the fresh catalyst liquid, whereas the solid 
is sent to the waste catalyst treatment step or regeneration step as it is 
or after being subjected to repetitions of recrystallization as conducted 
in the same manner as described above referring to said state (a). 
The state (c) is such that the catalyst layer is once separated into a 
light liquid phase and a heavy liquid phase at about -20.degree. C. while 
gradually lowering the temperature of the catalyst layer at the specific 
concentration, and a solid begins to deposit in the heavy liquid phase at 
about -65.degree. C. while further lowering the temperature. Then, the 
heavy liquid phase is separated into a mother liquor and the solid by the 
ordinary solid-liquid separating means such as centrifuge, filtration, 
etc. The mother liquor mainly contains the catalytically active component 
and is returned to the reaction system after being supplemented with the 
fresh catalyst liquid. The solid is sent to the waste catalyst treatment 
step or regeneration step as it is, or after being subjected to 
repetitions of recrystallization as conducted in the same manner as 
described above, referring to the state (a). 
In the states (a) to (c), the catalytically inactive component is sent to 
the waste catalyst treatment step or regeneration step, but is preferably 
brought into contact with the raw material hydrocarbon, before being sent 
to said step, to remove a very small amount of catalytic poisons such as 
water, sulfur and excess aromatic compounds from the raw material 
hydrocarbon through reaction or adsorption of these catalytic poisons. 
Actually the catalytically active component and the catalytically inactive 
component are represented by the catalytic activity "A", and are relative 
to each other, and thus no distinct line can be drawn between the 
catalytically active component and the catalytically inactive component. 
Accordingly, whether the heavy liquid phase or the solid in the states (a) 
to (c) is reused or sent to the waste catalyst treatment step is not only 
determined only by the states (a) to (c), but also dependent upon the 
degree of the catalytic activity "A" in the respective states (a) to (c). 
The states (a) to (c) depend upon the composition of the raw material 
hydrocarbon, the temperature for depositing the solid, the history and 
concentration of catalyst, the temperature condition after the adjustment 
of concentration, etc. 
Sometimes, a small amount of the catalytically inactive component in the 
sludge state may be settled in the course of the conversion reaction. In 
such case, the settled waste catalyst can be removed from the reaction 
system, and a fresh catalyst in an amount corresponding to the amount of 
the removed waste catalyst can be supplemented. 
When the reaction product solution separates into the hydrocarbon layer and 
the catalyst layer, the catalyst layer can be treated in the presence of 
the hydrocarbon layer without removing the latter from the reaction 
product solution in the same manner as above to remove the catalytically 
inactive component. 
The catalytically active component obtained by removing the catalytically 
inactive component in the manner as described above can be reused in the 
hydrocarbon conversion reaction as it is, or after being supplemented and 
renewed with the fresh catalyst. Sometimes, the catalyst to be reused has 
a little lower catalytic activity "A" than the fresh catalyst, but there 
is practically no substantial difference therebetween in the ordinary 
hydrocarbon conversion reaction where the reaction is carried out for a 
considerably long time until the residual hydrocarbon concentration 
reaches almost an equilibrium concentration.

Raw material hydrocarbon containing catalytic poisons such as water, 
sulfur, aromatic hydrocarbons, etc. is led to a raw material hydrocarbon 
purification tank 3 through a line 2 by a pump 1, where the raw material 
hydrocarbon is brought into contact with a catalytically inactive 
component to be sent to a regeneration step to remove the catalytic 
poisons such as water, sulfur, aromatic hydrocarbons, etc. from the raw 
material hydrocarbon. After the purification, the raw material hydrocarbon 
is led to a decantor 35 and separated into an upper layer and a lower 
layer. The upper layer is successively led to reactors 4, 5 and 6 through 
a line 36 and subjected to reaction. A fresh catalyst solution or a 
catalyst component supplemented with the fresh catalyst liquid is supplied 
to the reactors through lines 4b, 5b and 6b. Reaction product hydrocarbon 
leaves the reaction system through the respective decantors 4a, 5a and 6a 
at outlets of the respective reactors through a line 9a. 
On the other hand, a mixture (reaction product solution) of a small amount 
of the hydrocarbon and a large amount of the catalyst component is 
withdrawn from the bottoms of the respective decantors 4a, 5a and 6a, and 
led to a decantor 8 through a line 7, or returned to the respective 
reactors 4, 5 and 6. In the decantor 8 the reaction product solution is 
separated into two layers, the upper being a hydrocarbon layer and the 
lower being a catalyst layer. The hydrocarbon layer is returned to any one 
of the reactors through a line 9. When a liquid in a sludge or tarry state 
separates from the catalyst layer in the decantor 8, the catalyst layer is 
led to a separator 11a through a line 10a, where the sludge, etc. are 
separated from the catalyst layer, and the upper layer is led to a 
pretreatment tank 11 or a decantor 13. As the sludge, the lower layer from 
the decantor 11a is led to the raw material hydrocarbon purification tank 
3 through a line 11b and a line 33, or led to a regeneration step or waste 
catalyst treatment step through a line 11c and a line 37. 
On the other hand, the catalyst layer from the decantor 8 is led to the 
pretreatment tank 11 through a line 10, where it is adjusted to a desired 
concentration of component metal. The catalyst layer at the desired 
specific concentration is led to a decantor 13 through a line 12. 
When the catalyst layer separates into a light liquid phase and a heavy 
liquid phase, they are separated from each other in the decantor 13. The 
light liquid phase mainly contains a catalytically active component, and 
is withdrawn through a line 14. When the catalyst layer does not separate 
into the two layers, the catalyst layer is led to a crystallization tank 
16 through a line 15. The heavy liquid phase withdrawn from the decantor 
13 is led to the crystallization tank 16 through the line 15. The heavy 
liquid phase or the unseparated catalyst layer is kept at a specific 
temperature in the crystallization tank 16 to deposit a solid, and then 
led to a centrifugal separator 18 through a line 17, where it is separated 
into the solid and a mother liquor. The mother liquor is withdrawn through 
a line 19 and/or led to a concentration tank 21 through a line 20, where 
it is concentrated. The concentrated liquid is then led to a 
crystallization tank 23 through a line 22, where it is cooled to deposit a 
solid, and further led to a centrifugal separator 25 through a line 24, 
where it is separated into the solid and a mother liquor. The mother 
liquor is withdrawn through a line 26 and led to the concentration tank 21 
through a line 26a and/or discharged through a line 26b. The solid 
separated in the centrifugal separator 18 is led to a recrystallization 
step. That is, the solid separated in the centrifugal separator 18 is led 
to a dissolution tank 28 through a line 27, where it is dissolved in a 
recrystallization solvent such as hydrogen fluoride, etc. The resulting 
solution is led to a crystallization tank 30 through a line 29 and cooled 
to deposit a crystal, and further led to a centrifugal separator 32 
through a line 31, where it is separated into the solid and a mother 
liquor. The solid is led to the raw material hydrocarbon purification tank 
3 through the line 33 and used to separate the catalytic poisons such as 
water, sulfur, excess aromatic hydrocarbons, etc. contained in the raw 
material hydrocarbon. The liquid in the raw material hydrocarbon 
purification tank 3 is led to the decantor 35 through the line 34, where 
it is separated into a raw material hydrocarbon layer as an upper layer 
and a catalytically inactive component (waste catalyst) that has reacted 
with the catalytic poisons or adsorbed the catalytic poisons as a lower 
layer. The raw material hydrocarbon layer is led to the reactor tank 4 
through the line 36, whereas the waste catalyst as the lower layer is led 
to the regeneration step or the waste catalyst treatment step through the 
line 37. 
The mother liquor separated in the centrifugal separator 32 is led to the 
dissolution tank 28 through a line 38 and reused as the recrystallization 
solvent, or withdrawn through a line 39. The solid separated in the 
centrifugal separator 25 is led to the dissolution tank 28 through a line 
42, and recrystallized together with the solid from the centrifugal 
separator 18 or alone. In the latter case, the solid from the centrifugal 
separator 25 is led to a dissolution tank 44 through a line 43, where it 
is dissolved in a recrystallization solvent such as hydrogen fluoride, 
etc., and the resulting solution is led to a crystallization tank 46 
through a line 45, where the solution is cooled to deposit a solid, and 
then the resulting liquid is led to a centrifugal separator 48 through a 
line 47, where it is separated into the solid and a mother liquor. The 
solid is led to the line 33 through a line 49, and further to the raw 
material hydrocarbon purification tank 3 through the line 33 together with 
the solid from the centrifugal separator 32. 
The mother liquor from the centrifugal separator 48 is led to the 
dissolution tank 44 through a line 50a and reused as the recrystallization 
solvent, or discharged through a line 50b. The light liquid phase from the 
line 14, and mother liquors from the lines 19, 26b, 39 and 50b are joined 
together at the line 40, supplemented with the fresh catalyst liquid from 
a line 41 to renew the catalytic activity, and led to the reactors 4, 5 
and 6, respectively or to at least one of these reactors. 
According to the present invention, the catalytically inactive component 
can be substantially removed from the catalyst liquid after the use of 
catalyst, and the remaining catalytically active component can be 
effectively used. Accordingly, an amount of a fresh catalyst liquid to be 
supplemented can be reduced. Thus, the present invention has a very 
remarkable industrial significance. 
The present invention will be described in detail below, referring to 
Examples. 
REFERENCE EXAMPLE 
40 ml of solutions of SbF.sub.5 in hydrogen fluoride at various 
concentrations and 40 ml (corresponding to 28 g) of raw material 
hydrocarbon were charged into an autoclave (net capacity: 200 ml) provided 
with an electromagnetic stirrer, and catalytic activity "A" of the fresh 
catalysts was determined. 
The composition of the raw material hydrocarbon was as follows: 
______________________________________ 
n-hexane 96.3% by weight 
isohexanes 2.0% by weight 
C.sub.6 -naphthenes 
1.7% by weight 
benzene 110 ppm 
______________________________________ 
Reaction conditions were as follows 
______________________________________ 
Temperature 25.degree. C. 
Pressure of 4 Kg/cm.sup.2 gauge (pressurized 
reaction system with hydrogen) 
Stirring speed 1,000 rpm 
______________________________________ 
Isomerization reaction was 4 times repeated in the presence of the same 
catalyst only by replacing the hydrocarbon layer, and an average value of 
the catalytic activity "A" obtained from the second to fourth reactions 
was made catalytic activity of a fresh catalyst. 
The period of one reaction was about 20 minutes, and the concentration of 
n-hexane in the reaction product was 35-60% by weight. The results of 
determination are given in the following Table 1. 
TABLE 1 
______________________________________ 
Catalytic activity of fresh catalyst 
Catalytic activity 
Catalyst Sb concentration 
"A" (g of raw 
amount of catalyst (% material/g of 
(g) by weight) Sb . min.) 
______________________________________ 
47 11.6 0.55 
44 8.6 0.54 
42 6.0 0.52 
______________________________________ 
The catalytic activity "A" in the following Examples was determined 
according to the same manner as above: 
EXAMPLE 1 
100 G of a solution of SbF.sub.5 (antimony pentafluoride) in hydrogen 
fluoride (SbF.sub.5 concentration: 30% by weight) and the same raw 
material hydrocarbon as used in Reference Example but saturated with 
hydrogen fluoride (i.e. 128 g of raw material hydrocarbon and 0.07 g of 
hydrogen fluoride) were charged into an autoclave (net capacity: 300 ml) 
provided with an electromagnetic stirrer, and subjected to isomerization 
reaction at 25.degree. C., while maintaining the reaction system under 4 
Kg/cm.sup.2 gauge by pressurizing the system with hydrogen. After the 
reaction was continued for 45 minutes, the composition of hydrocarbon 
layer reached almost an equilibrium. After the end of reaction the 
hydrocarbon layer was removed, and 70 g of the raw material hydrocarbon 
saturated with hydrogen fluoride as above mentioned was charged into the 
autoclave, and subjected to the reaction. The catalyst was repeatedly used 
by repetitions of such operations, and the catalytic activity was 
gradually lowered. When the catalytic activity "A" of the catalyst layer 
in the reaction product solution was lowered down to 0.41 (77% of the 
catalytic activity "A" of fresh catalyst), the reaction was discontinued, 
and the reaction product solution was left standing at room temperature to 
separate it into the hydrocarbon layer and the catalyst layer. 
80 G of the catalyst layer was transferred into a test tube-type reactor 
(net capacity: 100 ml) made of ethylene tetrafluoride-propylene 
hexafluoride copolymer, which will be hereinafter referred to as FEP, and 
subjected to concentration at 50.degree. C. under a subatmospheric 
pressure (430 mmHg) for one hour. The resulting concentrated blackish 
brown catalyst liquid (antimony concentration: 32% by weight) was left 
standing at 20.degree. C., whereby a white solid was deposited. The white 
solid was filtered off, whereby about 5 g of the white solid and 37 g of 
blackish brown mother liquor were obtained, which had catalytic activities 
"A" of 0.07 and 0.44, respectively. The mother liquor was supplemented 
with 15 g of a solution of SbF.sub.5 in hydrogen fluoride (SbF.sub.5 
concentration: 30% by weight) and 38 g of hydrogen fluoride as a fresh 
catalyst liquid to make the catalytic activity "A" 0.47, and reused in the 
isomerization reaction. 
EXAMPLE 2 
Isomerization reaction was repeated in the same manner as in Example 1, 
except that 2% by weight of benzene was added to the raw material 
hydrocarbon of Example 1, on the basis of the latter. When the catalytic 
activity "A" of the catalyst layer was lowered down to 0.24 (45% of the 
catalytic activity "A" of the fresh catalyst), the repeated use of the 
catalyst was discontinued. The resulting reaction product solution was 
left standing at room temperature to separate it into the hydrocarbon 
layer and the catalyst layer. The catalyst layer was colored dark violet, 
and 40 g of the catalyst layer was taken into a test tube made of FEP, and 
concentrated at 20.degree. C. under a subatmospheric pressure (25 mmHg). 
It was observed that a violet tarry matter was deposited on the tube wall 
when the liquid volume was reduced to about 2/3 of the initial volume. 
When the liquid volume was reduced to 1/2, the concentration was 
discontinued, and the concentrated solution was left standing at 0.degree. 
C. to separate it into a tarry heavy liquid phase and a light liquid 
phase. The light liquid phase and the tarry heavy liquid phase had 
catalytic activities "A" of 0.26 and 0.01, and weights of 13.5 g and 7.3 
g, respectively. 
The light liquid phase was left standing at -30.degree. C., whereby a white 
solid was deposited. By filtration, 8.5 g of a mother liquor having a 
catalytic activity "A" of 0.35 and 5.0 g of a solid having a catalytic 
activity "A" of 0.11 were obtained. The mother liquor was supplemented and 
renewed with the fresh catalyst liquid, and reused. 
EXAMPLE 3 
40 G of the catalyst layer remaining in the reactor used in Example 2 was 
transferred into a test tube made of FEP, and kept at -32.degree. C. for 
one hour while observing the inside state. After about 3 minutes, a 
liquid-liquid separation was started, and an upper layer was colored light 
yellow, and a lower layer was colored violet. Then, a violet precipitate 
was started to form, and successively formation of white precipitate was 
observed. Catalytic activity "A" of mother liquor after filtration was 
0.31, and that of the mixture of both precipitates was 0.17, and the 
weight of the former was 22.6 g, and that of the latter was 17.4 g. The 
mother liquor was supplemented and renewed with the fresh catalyst liquid, 
and reused. 
EXAMPLE 4 
Isomerization reaction was repeated in the same manner as in Example 1, 
except that an autoclave of net capacity 500 ml was used, and 250 g of a 
solution of SbF.sub.5 in hydrogen fluoride (SbF.sub.5 concentration: 50% 
by weight) was charged therein. 
After the catalytic activity "A" was lowered down to 0.22, a multi-stage 
crystallization test was conducted. That is, the reaction product solution 
was separated into a hydrocarbon layer and a catalyst layer, and 203.5 g 
of the catalyst layer of lowered activity was cooled at -75.degree. C. to 
deposit a solid. By centrifuge, 175.8 g of a mother liquor and 27.7 g of 
the solid were separated from each other as "mother liquor 1" and "solid 
1", respectively. All the amount of solid 1 was dissolved in 29 g of 
hydrogen fluoride at 20.degree. C., and the resulting solution was cooled 
at -75.degree. C. to deposit a solid. By centrifuge, 26.5 g of a mother 
liquor and 30.2 g of the solid were separated from each other as "mother 
liquor 2" and "solid 2", respectively. 
Furthermore, all the amount of solid 2 was dissolved in 14.3 g of hydrogen 
fluoride at 20.degree. C., and the resulting solution was cooled at 
-75.degree. C. to deposit a solid. By centrifuge, 8.3 g of a mother liquor 
and 36.2 g of a solid were separated from each other as "mother liquor 3" 
and "solid 3", respectively. The results are shown in Table 2. SbF.sub.5 
balance throughout the process was 95.8%. It is seen from the results that 
separation of catalytically inactive component was more completely carried 
out by the multistage crystallization. 
Mother liquor 1 was supplemented and renewed with 55 g of a solution of 
SbF.sub.5 in hydrogen fluoride (SbF.sub.5 concentration: 65% by weight) to 
make the catalytic activity "A" 0.409, and reused. 
TABLE 2 
______________________________________ 
Results of multistage crystallization test 
Antimony con- 
Catalytic activity 
Weight centration (g of raw material/ 
(g) (% by weight) 
g of Sb . min.) 
______________________________________ 
Catalyst liquid 
203.5 23.2 0.220 
Mother liquor 1 
175.8 17.9 0.321 
Solution of 
solid 1 56.7* 27.6** 0.165 
Mother liquid 2 
26.5 23.2 0.222 
Solution of 
solid 2 44.5* 21.9* 0.112 
Mother liquor 3 
8.3 23.6 0.131 
Solution of 
solid 3 38.3* 20.2** 0.101 
______________________________________ 
*weight of solution of the solid in HF 
**Sb concentration in each solution of solid 1, 2 or 3. 
EXAMPLE 5 
A multistage continuous isomerization reaction was carried out in three 
autoclaves each having a net capacity of 500 ml arranged in series and 
each provided with an electromagnetic stirrer and a decantor at their 
outlets. 150 g of a solution of SbF.sub.5 in hydrogen fluoride (SbF.sub.5 
concentration: 50%) was charged into each of the autoclaves as a catalyst, 
but no more catalyst was charged thereafter. 
As a raw material hydrocarbon, straight run naphtha (1.8% by weight of 
butanes, 43.6% by weight of pentanes, 44.6% by weight of hexanes, 1.5% by 
weight of cyclopentane, 5.5% by weight of methylcyclopentane, 2.6% by 
weight of cyclohexane, 0.4% by weight of heptanes, and 220 ppm of benzene) 
was fed to the autoclaves at a rate of 330 g/hr under reaction conditions 
such as temperature: 25.degree. C., stirring speed: 850 rpm, and pressure: 
4.0 Kg/cm.sup.2 gauge (pressurized with hydrogen). After operation for 180 
hours, the catalyst liquids of the respective autoclaves were transferred 
to a crystallization apparatus made of Kel-F (trademark of chlorotrifluoro 
ethylene polymer) and sufficiently mixed. Total catalyst liquid amounted 
to 486 g. A portion of the catalyst liquid was used to determine the 
catalytic activity "A", and it was found to be 0.38 (which was 70% of the 
activity of the fresh catalyst). 
The catalyst liquid was cooled at -62.degree. C. for 4 hours, whereby a 
solid was deposited, and had an antimony concentration of 17% by weight. 
By forced filtration, 96 g of a solid and 380 g of a mother liquor were 
obtained. The mother liquor had a catalytic activity "A" of 0.41 and was 
admixed with 94 g of a solution of SbF.sub.5 in hydrogen fluoride 
(SbF.sub.5 concentration: 30% by weight), and sufficiently mixed and 
renewed so that the catalytic activity "A" could be 0.43 and reused (the 
reuse will be exemplified in Example 11). 
The solid was dissolved in 24 g of hydrogen fluoride at 20.degree. C., and 
the resulting solution was cooled at -75.degree. C. to effect 
recrystallization, and 57 g of a solid was obtained thereby. The antimony 
concentration of the solid was 26.3% by weight, and the catalytic activity 
"A" thereof was 0.18. 
EXAMPLE 6 
Isomerization reaction was carried out in the same manner as in Example 1, 
except that 100 g of a solution of SbF.sub.5 in hydrogen fluoride 
(SbF.sub.5 concentration: 30% by weight) was used. When the catalytic 
activity "A" was lowered down to 0.38 (69% of the catalytic activity "A" 
of the fresh catalyst), repeated use of the catalyst was discontinued. 90 
G of the catalyst layer from the reaction product solution was transferred 
into a test tube-type reactor (net capacity: 100 ml) made of FEP, and the 
catalyst layer was concentrated to about 1/2 of the initial liquid volume 
at 10.degree. C. to 20.degree. C. by streaming a nitrogen gas through the 
catalyst layer. The concentrated catalyst liquid had an antimony 
concentration of 25% by weight, and then cooled at -80.degree. C., whereby 
a white solid was deposited. By filtration, 21 g of the white solid and 34 
g of a mother liquor were obtained, and had catalytic activities "A" of 
0.23 and 0.42, respectively. The mother liquor was reused. 
EXAMPLE 7 
Isomerization reaction was repeatedly carried out in the same manner as in 
Example 6, and when the catalytic activity "A" was lowered down to 0.36, 
the repeated use of the catalyst was discontinued. 80 G of a catalyst 
layer from the resulting reaction product solution was transferred into a 
test tube-type reactor (net capacity: 100 ml) made of FEP, and 
concentrated at 30.degree. C. under a subatmospheric pressure (65 mmHg). 
After the concentration, the antimony concentration was 25% by weight. The 
concentrated solution was cooled at -60.degree. C., whereby a white solid 
was deposited. By filtration, 21 g of the white solid and 23 g of a mother 
liquor were obtained, and had catalytic activities "A" of 0.21 and 0.41, 
respectively. The mother liquor was reused. 
EXAMPLE 8 
Isomerization reaction was repeatedly carried out in the same manner as in 
Example 6, and when the catalytic activity "A" was lowered down to 0.34, 
the repeated use of the catalyst was discontinued. 80 G of a catalyst 
layer from the reaction product solution was transferred into a test 
tube-type reactor (net capacity: 100 ml) made of FEP, and concentrated at 
30.degree. C. under a subatmospheric pressure (65 mmHg). After the 
concentration, the antimony concentration was 31% by weight. 
The concentrated solution was cooled at -85.degree. C., whereby a light 
liquid phase and a large amount of a heavy liquid phase were separated 
from each other. 4 G of the light liquid phase (catalytic activity "A" 
0.45) was removed therefrom, and the remaining heavy liquid phase was 
maintained at -55.degree. C., whereby a white solid was deposited. By 
filtration, 18 g of the solid and 14 g of a mother liquor were separated 
from each other. The mother liquor and the solid had catalytic activities 
"A" of 0.40 and 0.15, respectively. The light liquid phase and the mother 
liquor were joined together, and the resulting mixture was supplemented 
with the fresh catalyst liquid, and reused. 
EXAMPLE 9 
200 G of a solution of SbF.sub.5 in hydrogen fluoride (SbF.sub.5 
concentration: 50% by weight) (catalytic activity "A": 0.55) was charged 
into an autoclave (net capacity: 350 ml) provided with a settling tank 
(net capacity: 25 ml) made of FEP at the bottom of the autoclave, and 
straight run naphtha (1.5% by weight of butane, 42.8% by weight of 
pentane, 44.5% by weight of hexane, 1.5% by weight of cyclopentane, 5.5% 
by weight of methylcyclopentane, 2.6% by weight of cyclohexane, 0.4% by 
weight of heptane, and 1.2% by weight of benzene) saturated with hydrogen 
fluoride was continuously supplied to the autoclave at a rate of 120 g/hr 
under reaction conditions such as temperature: 25.degree. C., stirring 
speed: 800 rpm, and pressure 4.0 Kg/cm.sup.2 gauge (pressurized with 
hydrogen). After a continuous operation for 150 hours, 17.8 g of brownish 
violet precipitate was accumulated in the settling tank. 
When the resulting mother liquor was left standing at room temperature for 
about 3 minutes, it separated into two layers, the upper being a product 
hydrocarbon layer and the lower being a catalyst layer. The catalytic 
activity "A" of the precipitate was 0.12, whereas that of the catalyst 
layer was 0.36 and the amount of the catalyst layer was 222.2 g. The 
catalyst layer was supplemented with the fresh catalyst liquid, and 
reused. 
EXAMPLE 10 
Isomerization reaction was carried out in the same manner as in Example 9, 
and after a continuous operation for 100 hours, the reaction was 
discontinued. The reaction product solution was transferred into a vessel 
(net capacity: 500 ml) made of FEP, and left standing at room temperature, 
whereby 170 ml of a catalyst layer and 75 ml of a hydrocarbon layer were 
separated from each other. The entire amount of the catalyst layer and the 
hydrocarbon layer was kept at -45.degree. C. for one hour while stirring 
at 500 rpm, whereby 43 g of a white precipitate was formed. A mother 
liquor freed from the white precipitate was left standing at room 
temperature, whereby a hydrocarbon layer and a catalyst layer were 
separated again from each other. The catalytic activities "A" of the 
precipitate and the catalyst layer freed from the precipitate were found 
to be 0.23 and 0.37, respectively. The catalyst layer freed from the 
precipitate amounted to 176 g, and was supplemented with the fresh 
catalyst liquid, and reused. 
EXAMPLE 11 
Isomerization reaction was carried out in the same manner as in Example 5 
except that 474 g of the catalyst renewed in Example 5 was equally charged 
into the three autoclaves in place of the fresh catalyst. As the result, 
concentrations of remaining n-pentane and n-hexane in the reaction product 
solution are shown in Table 3. 
TABLE 3 
______________________________________ 
Fresh Renewed 
Raw catalyst catalyst 
material 
(Ex.5) (Ex. 11) 
______________________________________ 
Time (hr) 0 50 120 180 50 120 180 
n-pentane (wt%) 
24.5 7.4 7.9 8.7 7.2 7.6 8.2 
n-hexane (wt%) 
21.4 2.7 3.2 3.8 2.8 3.1 3.5 
______________________________________ 
It is obvious from Table 3 that, though there are some difference between 
the catalytic activity "A" of the renewed catalyst and that of the fresh 
catalyst, there is no substantial difference in the concentrations of 
remaining n-pentane and n-hexane between the renewed catalyst and the 
fresh catalyst when used, and that the renewed catalyst can be used 
equally to the fresh catalyst. 
Such phenomena can be always observed in the ordinary hydrocarbon 
conversion reaction which is carried out for a considerably long period of 
reaction time until the concentrations of the remaining hydrocarbons reach 
their equilibrium concentrations. 
EXAMPLE 12 
Isomerization reaction was carried out by charging 100 g of a solution of 
SbF.sub.5 in hydrogen fluoride (SbF.sub.5 concentration: 30% by weight) 
and 73 g of raw material hydrocarbon containing 1.3% by weight of butanes, 
42.3% by weight of pentanes, 43.4% by weight of hexanes, 7.8% by weight of 
C.sub.5 -C.sub.7 naphthenes, 4.4% by weight of heptanes and 0.8% by weight 
of benzene, saturated with hydrogen fluroide in an autoclave (net 
capacity: 300 ml) provided with an electromagnetic stirrer, while 
maintaining the reaction system at 25.degree. C. and 4 Kg/cm.sup.2 gauge 
by pressurizing the reaction system with hydrogen. After the reaction for 
50 minutes, the composition of the hydrocarbon layer reached almost an 
equilibrium. After the end of reaction, the hydrocarbon layer was removed 
therefrom, and 73 g of the raw material hydrocarbon saturated with 
hydrogen fluoride as above mentioned was again charged into the autoclave 
and subjected to reaction. By repeating such operations, the catalyst was 
repeatedly used. The activity of the catalyst was gradually lowered. 
When the catalytic activity "A" was lowered down to 0.38, 115 g of the 
catalyst layer from the resulting reaction product solution was 
transferred to a test tube-type vessel made of FEP, and left standing at 
room temperature whereby a brownish violet tarry heavy liquid phase and a 
light brown light liquid phase were separated from each other. After the 
separation of 6 g of the heavy liquid phase and 109 g of the light liquid 
phase, their catalytic activities "A" were determined. The heavy liquid 
phase had a catalytic activity "A" of 0.03, whereas the light liquid phase 
had that of 0.39. Then, the light liquid phase was kept at -42.degree. C., 
whereby about 18 g of white precipitate was separated. The precipitate had 
a catalytic activity "A" of 0.18, whereas the resulting mother liquor had 
that of 0.42 and amounted to 82 g. The mother liquor was supplemented with 
15 g of a solution of SbF.sub.5 in hydrogen fluoride (SbF.sub.5 
concentration: 70% by weight) to make the catalytic activity "A" 0.47, and 
then the isomerization reaction of the raw material hydrocarbon was 
continued with the renewed catalyst liquid.