Note: Descriptions are shown in the official language in which they were submitted.
lO~J-1SRO
,
The present invention relates to a method of disposing of poly-
chlorinated biphenyl~ without cauqing a health hazard to the public.
More particularly, the present invention relates to a method of
converting polychlorinated biphenyls into useful compounds by the
hydrogenation-dechlorination thereof.
It is known in the art that polychlorinated biphenyls (hereinafter
referred to as PCB) is a useful substance for a transformer oil, a
capacitor oil, a heat transfer agent and a carbonless reproducing paper;
it has been in wide use for theqe applications. On the other hand,
in view of the recent increased public interest to pollution problems
the toxic nature of PCB has also drawn its attention, and the recovery
of unused PCB has been started. However, a further problem has been
brought about as to how to dispose of it without cauqing a health
hazard to the public. So far many proposalq have been made for disposing
of the unused PCB, such as incineration, ultraviolet--decomposition, hydro-
thermal decomposition, radiololysis. However, it has been found that
the disposal of it under these methods is not satisfactory. Under the
incineration methods it is imposqible to consume PCB completely by fire,
and additionally, it is likely to cause air contamination. Under the
ultraviolet decomposition method the biphenyls and salts produced
constitute a bar to the transmission of ultraviolet rays. The
radiololysis methods are effective only when the PC~ to be treated is
extremely diluted, and have no practical value. Lastly, under the hydro-
thermal decomposition methods it is required to conduct them under
the condition of elevated temperatures and high pressures (e.g. at 300C,
200atm), and the products produced through the methods are not
identified, thereby making it diffic~llt to flow them away to the se~age.
The present invention aims at overcoming the difficulties of
th~ ~own methods of disposing of PCB, and has for its object to provide
~r,
10~'~580
an improved method for the safe disposal of PCB, on the
basis of the discovery that PCB can be converted into
various useful compounds, when PCB, emulsified and d s-
persed in an alkaline aqueous solution, is reacted with
hydrogen in the presence of hydrogenation catalyst,
wherein it has been found that these useful compounds
are the by-products of the hydrogenation-dechlorination
of the PCB.
Therefore, according to the present invention the
disposal of PCB includes the steps of emulsifying and
dispersing PCB in an alkaline aqueous solution, and
reacting the same with hydrogen in the presence of
hydrogenation catalyst.
The sequence of the addition of alkali, water, an
emulsifyiny-dispersing agent, and PCB is not important
provided the PCB is suitably emulsified and dispersed
in the alkaline aqueous solution.
As described above, according to the present invention
a great deal of PCB is dechlorinated and converted into
various useful compounds, wherein the hydrogen chlorides
produced through the reaction of PCB with hydrogen are
changed into harmless salts 7 and wherein the products
obtained in this way are separately collected. In addi-
tion, according to the present invention there is no need
for setting the condition of high temperatures and high
pressures, but it is practicable under a normal condition.
The general formula of PCB is expressed as follows:
~ (1 _ m + n _ 1 0)
Clm Cln
E~
10~ ~80
The method of this invention is applicable either
to individual compounds expressed above or to a mixture
thereof.
Under the method of this invention PCB is firstly
converted into biphenyl as a result of dechlorination
through a hydro-dechlorinating reaction, and a part
of the biphenyl is converted into bicyclohexyl
- 2a -
F`-
109 ~S80
i
through hydrogenation. In this case, it is also possible to let the
reaction keep on until the whole amount of biphenyl is converted into
bicyclohexyl. Depending upon the reaction condition~ it is possible
to obtain benzene and any other dechlorinated products.
In this invention it is essential to emulsify and disperse PCB in
an alkaline aqueous solution, thereby enabling the PCB to react with
hydrogen effectively. The resulting hydrogen chloride reacts with
the alkali content in the solution, thereby producing a harmless salt.
In this way the reaction smoothly proceeds. It has been found through
experiments that a Raney nickel-catalyst preferably needs the parallel
use of alkali for its lasting activity; otherwise the activity will not
last. The alkali used for this invention can be selected from known
ordinary types as long as they can react with hydrogen chloride to
produce salts, such as sodium hydroxide, potassium hydroxidel calcium
hydroxide, sodium carbonate. The amount of alkali to be used depends
upon that of PCB to be treated, but it is necessary to use a
~ufficient amount to react with the whole amount of hydrogen chloride
produced through the reaction of PCB with hydrogen. It is permissible
to use a slightly excessive amount of alkali.
It has been also found that ~Then the alkali is one normal or less
a better emulsifying and dispersing of PCB will be resulted, whereas
when it is as highly concentraded as to exceed one normal the emulsifying
and disper~ing thereof will decelerate, thereby resulting in a retarded
reaction. In addition, it has been found that the reaction smoothly
proceeds when the equivalent ratio to PCB ranges from 0.5 to 1.25,
preferably from 0.7~ to 1.1 (especially in the range of 0.5 to 1.0 the
reaction velocity is relatively high until it reaches the point of
neutralization). Accordingly the amount of alkali is restricted by
that of PCB to be treated, and it determines the minimum amount of a
10~-~580
dispersing medium. Furthermore, it has been found that the
alkali and the reduction circumstances are effective to
protect the reaction chamber, and that irrespective of the
high concentration of alkali the Raney nickel catalyst main-
tained its activity after the reaction was finished.
Preferably a suitable emulsifying-dispersing agent is used
to emulsify and disperse PCB in an alkaline aqueous solution.
For this agent methyl alcohol, ethyl alcohol, isopropyl
alcohol, acetone, and any other water soluble organic solvents,
and surface active agents as long as they are effective to
emulsify and disperse PCB in the alkaline aqueous solution are
appropriately used. Its amount is not limited, but in the case
of water soluble organic solvents, such as methyl alcohol, it
is preferred that 20 to 50g is used against lOOg of water,
wherein the exact figure depends upon the number of chlorides
contained in the PCB to be treated. These agents can be used
singly or in a combination.
In cracking PCB the ratio of water to the emulsifying-
dispersing agent is 1.3 to 4:1, preferably 2:1 so as to secure
the minimum amount of a dispersing medium. The amount of the
emulsifying-dispersing agent affects the emulsifying and
dispersing of PCB; neither excess nor shortage produces a
good result. In making a solution containing a dispersed
PCB it is also possible to use the same amount of emulsifying-
dispersing agent as that of water, and in this case it has
been found that methyl alcohol makes hydrogen most soluble of
the three; then ethyl alcohol, and finally isopropyl alcohol.
The adding ratios of PCB, alkali an emulsifying-
dispersing agent, and water are prefereably determined such
30 that the solution of 800 to 2000ml, preferably 900 to 1200ml,
should contain alkali of 0.5 to 1.25 gram equivalent weight
(preferably 0.75 to l.lgram e~uivaient weight)
~o~s~o ~:
.
and an emulsifying-dispersing agent of 100 to 450ml (preferably 170
to 380ml) with respect to chloride of l.Ogram contained in the PCB.
~ or the emulsifying-dispersing agents for use in this invention
known types can be safely selected and used, e.g. Raney catalysts~, such as
M Raney nickel catalyst, a Raney cobalt catalyst; modified Raney
cataly~ts (which are produced by the addition of lead, antimony, etc. t~
a nicke~-aluminium alloy); platinum; palladium, and rhodium. These
cataly~ts can be used singly or in a combination of two or more. The
amount to be used depends upon the type of the catalyst and the reaction
conditions, and can be determined in a wide range. For example, a 10%
~arbon-supported palladium catalyst of 1 to 3gram can be used with
~espect to lOOgram of PCB (AC 125~). It has been found that the Raney
nickel catalyst is very reactive in the alkaline and neutral zones up~to
160C
- The desired pressures for carrying out this invention range from
normal to lOOatm, preferably 3 to 30atm, and they are adjusted in
accordance with the pressure of hydrogen. It is preferred to use a
greater amount of hydrogen than that calculated on principle. The hydroge-
native dechlorination reaction has been found to be almost free from
the pressure, and therefore, its reaction velocity can be considered
constant whether the initial pressure is lOOatm or 30atm. Even if
the partial pressure of hydrogen is 1 to lOkgw~cm2, the reaction
proceeds, and its velocity is comparable to when the pressure is high.
The method of this invention can be performed at a room temperature, but
the higher the temperature is, the more the reaction accelerates.
However, w~en the temperature exceeds 200 C it may happen that the
hydrogenation catalyst, such as a Raney catalyst, loses its activity,
and it is preferred to carry out the reaction at a temperature of
50 to 200C, preferably 70 to loOC, particularly for an industrial
109~5130
,. i ~ .
utilization. A period of time for which the reaction ccmpletes
depends upon the activity of the catalyst, the reaction temperature and
other factors, but normally it almost complete; in 0.5 to 48 hours.
The viscosity of PCB increases as the av~rage number of chlorides
increases with a rising pour point, thereby making the qame difficult
to become emulsified and dispersed in the solution. A 10-chloride
compound has almost the same fluidity at 160 C as that of a 4-chloride
compound at 100C, so that there is no difficulty for the same to
become emulsified and dispersed, thereby enabling the reaction to proceed
smoothly. In this case, it has been found that the elevation of the
temperature makes the emulsifying and dispersing develop, and that
the agitation of the solution also favorably affects the emulsifying
and di~persing in keeping on as well as proceeding. In the case of
a Raney nickel catalyst the practicable range of temperatures for the
hydrogenation i~ up to 160 C in view of the effective continuation of
activity. The reaction velocity tends to multiply 2 to 4 times in
the range of 70 .~ to 200 C as the temperature rises by 10 C.
A typical example of the operation according to the present
invention will be explained:
A hydrogenation catalyst, alkali, water and a dispersing agent
are added in a high pressure container, such as an autoclave,
in which a PCB is evenly emulsified and dispersed. ~hen hydrogen is
introduced into the container, and the reaction is effected atthe required
temperature under therequired pressure. After t~e reaction is finished,
the products will be separated into each compound by fractional distil-
lation at the utilization of differences in their boiling points, and be
individually purified.
Alternatively, the following method is al~o possible:
Since the mixture in the container becomes ~radually separated
109~51~0
into products in the upper portion of the container and an u~reacted
PCB in the lower portion thereof, in the course of the rcaction, the
products in the upper portion are taken out while the reaction is being
stopped, followed by a fresh supply of PCB to the remainder in
the container. In this way the reaction resumes in the container,
whereas the products obtained are separated into each compound by
partial distillation.
As the th~rd alternative way it is also possible that the mixture
in the contAiner is separated into an unreacted PCB and products by
distillation in a closed system while the reaction is being stopped,
in view of the remarkably high boiling point of PCB compared with those
of the products. The products obtained in this way are separated into
each compound by distillation.
A Brief Explanation of the Drawing:
FIGURE 1 is a graph depicting the relationship between the
rate of dechlorination and the amount of an emulsifying-dispersing
agent in a hydrogenation-dechlorination reaction of PCB having 4
-chlorid0s (reaction temperature: 100 C, reaction hour: 3hrs);
FIGURE 2 is a graph depicting the relationship among the amount
of sodium hydroxide, the rate of dechlorination and a pressure drop
(the emulsifying-dispersing agent: isopropyl alcohol, reaction temperature
100 C, reaction hour: 3hr~)
The present invention will be better understood by the following
examples:
EXAMPLE 1
9-0~ of PCB (made by Mitsubishi-Monsanto C-.Ltd. AC 1249, the
average number of chlorides: 3), having 0.105gram equivalent weight,
4.2g of sodium hydroxide (0.105 gram equivalent weight)~ and 20ml of
isopropyl alcoholwere niixed, to which lOg of powdered Ni-Al alloy
~ (Ni: 50%) was added as a catalyst together with water,:
~094S80
wherein the powdered Ni-Al alloy was previously develoI)ed at 50 C for
50 minutes with 45ml of 30% solution of sodium hydroxide,until the
total amo~nt reached lOOml. This dispersing solution was added in an
autoclave capable of osillation (with a Nickrome heater, capacity: 250m],
and hydrogen was introduced. Then the reaction was effected at 100 C
under about lOOIcgw/cm of Hg total pressure,, wherein the vapor pha4e
was 150ml. Table 1 shows the re:Lationshi,p amons the tot~l pressure
of hydrogen in the autoclave, the rate of dechlorination and the
reaction hour:
109~S~0 ~ ~
. ~ ~
.. _ _ _ _ . ... . . . .
TABLE 1
REACTION HOUR PRESSURE 0~ Hg RATE OF DECHLORINATION( )
(hour) (kg / cm ~ (
102.8 o,o
1 92.2 ~20.0)
2 88.o (llO.O)
3 85.o (50.5)
4 82.5 (70.5)
80.3
67.o .. (93.0)
24 62.8 g8.o
(~) The rate of dechlorination was given by measuring the
chloride produced in the form of sodium chloride by the
sil~er chloride gravimetric method.
The parenthes:ized figures were obtained by experiments
individually renewed for each stage.
It was ascertained through a gas chromatography and a gas chro-
matography-mass spectrometry that the PCB had been converted into a
great amount of biphenyl and a small amount of bicyclohexyl. In
addition, it was ascertained by an ignition test on the filter paper
that the catalyst maintained its activity after the reaction was
finished.
EXAMPLE 2
The hydrogenation-dechlorination reaction was carried out in
the same manner as Example 1, except for the reaction temperature,
that is~ at 160 C. The relationship among the pres~ure of hydrogen in
the autoclave, the rate of dechlorination and the reaction hour are
~hown in Tabl e 2:
109~580
TA~LE 2
REACTION HOURPRESSURE 0~ Hg RATE OF DECHLORINATION
(minute~ (kg / cm ) . . (%)
0 100.0 0.0
92.5 (38.o)
3 85.o (78.o)
65.5 (85.o)
120 . 67.o . 97.5
It was ascertained by an ignition test on the filter paper that
the catalyst maintained it~ activity after the reaction was fini~hed.
EXAMPLE 3
The hydrogenation-dechlorination reaction was carried out
in the same manner as Example 1, except for the reaction temperature,
that is, at 200 C. The relationship among the pressure of hydrogen in
the autoclave, the rate of dechlorination and the reaction hour are
shown in Table 3:
TABLE 3
REACTION HOURPRESSURE 0~ Hg RATE OF DECHLORINATION
(minute) (kg / cm ) (%)
0 100.0 0.0
~2.0 ' 50.0
80.2 82.5
~0 60.0 91.5
It was aqcertained by An ignition test on the filter paper that
the catalyst maintained its activity after the reaction was finished.
EXAMPLE 4
In~tead of the isopropyl alcollol in EXAMPLE 1 20ml of m~thyl
10~'1S80 ~ !
~ . - . I ,
. . .
. .
alcohol was used to carry out the hydrogenation-dechlorination
reaction. The relationship between the pressure of hydrogen in the
autoclave and the reaction hour is shown in Table 4:
TABLE 4
REACTION HOUR PRESSURE 0~ Hg
(hour) ( kg / cm
0 133.5
1 124.5
2 114.5
3 107.0
4 97.5
9-5
6 90.0
24 89.0
After 24 hours it was found that the rate of dechlorination
reached 87%, and it was a~certained by an ignition test on the filter
paper that the catalyst maintained its activity after the reaction
was finished.
EXAMPLE 5
The hydrogenation-dechlorination reaction was carried out
in the same manner as Example 1, except for 20ml of acetone for the
catalyst and under a 70kgw/cm total preqsure of hygrogen. The
reaction was continued for 20 hours, and the relationship amonS the
reaction hour, the pressure of hygrogen and the rate o dechlorination
is shown in Table 5:
(Table 5 is on the next page)
:1.0 -~
~ 10!~580
. . ~ i
_ . .
:`
TABLE 5
Reaction temperature: 100C
REACTION HOURPRESSURE 0~ Hg RATE OF DECHLORINATION
(hour) (kg / cm ) (%)
70.5 0.0
0.25 51.5
o.5 38.1
1.0 34.0
1.5 31.2
2.0 27.2
18.0 2.5
19 . 2~4
2~4 100.0
After the reaction the Raney nickel catalyst was found in black
and sludgy, and it was ascertained by an ignition test on the filter
paper that the catalyst had no more activity. It was also found thro~gh
a gas chromatography and a gas chromatography-masq spectrometry that
the PCB had been converted into biphenyl and bicyclohexyl, and that
the acetone had been converted into isopropyl alcohol.
EXAMPLE 6
Instead of the acetone in Example 5 20ml of ethyl alcohol was
used to carry out the hydrogenation-dechlorination reaction. The
relationship among the reaction hour, the pressllre of hydrogen and .
the rate of dechlorination is shown in Table 6:
TABLE 6
Reaction temperature: 100C
REACTION HOUR PRESSURE 0~ Hg Rate OE DECHLORINATION
(hour) ~kg / cm ) (%)
72.0 .0
-- 11 --
109'~30 `' '' I
0.5 69.6
1 67.7
1.5 67.o
2.0 66.2
18 45.5
19 45.4
44.4 - 92.0
After the reaction was finished, it was ascertained by an ignition
test on the filter paper that the Raney nickel catalyst maintained
its activity, and it was also ascertained through a gas chromatography
and a gas chromatography-mass spectrometry that a great amount of
biphenyl and a small amount of bicyclohexyl had been produced.
EXAMPLE 7
The hydrogenation dechlorination reaction was carried out, using
a PCB having 3 chlorides on an average, under 30kgw/cm total pressure
of hydrogen but at various temperatures, that is, 100 C, 160 C and
200 C. The relationship among the reaction hour, the pressure of
hydrogen and the rate of dechlorination is shown in Tables 7, 8 and 9.
o Herein the page 12' is inserted.
TABLE 7
Reaction temperature: 100C
REACTION HOURPRESSURE OE2Hg RATE OF DECHLORINATION
(hour)~kg / cm ) (%)
32.0 o. O
1 25.5 (31.')
2 22.5 (53.~))
3 1~.0 (50.6)
.5.2 (80.3)
ll.o
- 12
5~30 ,...,
B In an autoclave 9g of PCB (AC 1242~, 20ml of isopropyl alcohol,and 4.2g of sodium hydroxide were mixed, to which 10g of a Raney
nickel alloy powder (Ni: 40%) and about 74ml of water were added
until the whole liquid phase containing the catalyst reached 100ml.
The Raney nickel alloy powder had been previously developed at 60 C
for 50 minutes in a 55ml of 20% sodium hydroxide solution.
It was found that at the temperatures of 160 and 200 C the partial
pressures of the dispersing agent (isopropyl alcohol) and water rose,
and 150ml of hydrogen was introduced into the autoclave such that the
total pressure at each temperature could maintain 3Okg/cm .
- 12 ~ -
10~A1S80
:`
6 7.2 (~3.7)
18hour/25min 4.0 96.1
TABLE 8
Reaction temperature: 160C
REACTION HOUR PRESSURE O~ Hg RATE OF` DECHLORINATION
(minute) (kg / cm ) (~)
26.4 0.0
22.0
20.5
19.0
17.0
15.0 61.2
TABLE 9
Reaction temperature: 200C
REACTION HOUR PRESSURE O~ Hg RATE OF DECHLORINATION
(minute) (kg / cm ) (%)
52-5 0.0
40.5 5~-3
After the reaction was finished, it was found that the Raney
nichel catalyst in the reaction at 100 C maintained such an activity
that it ignited as vigourously as before the reaction, when the
same was cleansed with ethyl alcohol, and that the catalyst in the
reaction at 160 C ignited when the same was cleansed~with acetone.
On the other hand, the catalyst in the reaction at 200 C did not ignite
even wllen the same was c]eansed ei-thcr with ethyl ulcollol or acetone.
It was ascertained through a gas chromatosraphy and a gas chromato-
sraphy-mass spectrometry tha-t a sreat amount o~ ~-iphenyl and a small
- 1,3 ~
~0!~4580
. ') .,' .
~ , ., . . , _~
.
amount of bicyclohexyl had been produced.
EXAMPLE 8
This experiment was effected with the use of a PCB having 4
chlorides on an average, at 100C under a 30kg~cm to-tal pressure of
hydrogen, the results of which are shown in ~ ble 10. 7.65g of PCB
~ 09~f ~o~
t (produced by Kanegafuchi Kagaku Co., Ltd. KC-400~) having 0.105 gram
equivalent weight, 20ml of isopropyl alcohol, and 4.2g of sodiumhydroxide
(equivalent weight ratio to the PCB: 1) were mixed in an autoclave, to
which lOg of a Raney nickel alloy powd~r (Ni: 40%) wa~ added together
with water (about 63ml) until the whole amount of the solution reached
lOOml, wherein the Raney nickel alloy powder wae previously developed
at 60 C for 50 minutes in 55ml of 20% solution of sodium hydroxide.
into the autoclave
Then hydrogen was introduced~sufficiently to secure that the total
pressure thereof reached 30kg/cm .
TABLE 10
Reaction temperature: 100C
REACTION HOURTOTAL PRESST2RE OF Hg RATE OF DECLORINATION
~hour)(kg / cm ) (%)
0 31.2 O.Q
0.5 25.2
1 21.2
1.5 17~IL
2 1ll.0
2.5 11.3
3 8.2 98-5
Twenty-four hours after the reaction was finished, it was found
by a~ ~gnition test that the Raney nickel catalyst showed the same
igniting ability as before the reaction, which demonstrated that it
maintained its catalytic activity. In addition, it was ascertained
through a gas chromatography and a gas chromatography-mass specrometry
that a great amount of biphenyl and a small amount of bicyclohexyl had
~- 10~580
.~
been produced~
Comparative Test ~1)
The reaction was carried out in the same manner as Example 8,
except for non-use of alkali. The relationship among the reaction
hour, the total pressure of hydrogen and the rate of dechlorination
is shown in Table 11:
TABLE 11
REACTION HOUR TOTAL PRESSU ~ OF Hg RATE OF DECHLORINATION
(hour)(kg / cm ) (%)
0 34.2 0.0
0.5 34-3
1 33-6
1.5 33.3
2 33-
2.5 32-7
3 32.6 15.0
it was found that
After the reaction was finished~thepH had changed into about 5.5.
The catalyst was found in black and sludgy, and an ignition test did
not show that the catalyst maintained its activity , which showc that
without alkali the catalytic activity does not last, thereby resulted
in a short life of reaction.
Comparative Test (2)
A hydrogenation-dechlorination reaction was effected in the
same manner a~ Example 8, except for non-use of the emulsifying-
dispersing agent. The relationship among the reaction hour, the
total pressure of hydrogen, and the rate of deehlorination is shown
in Table 12:
- 15
5~qO
'` .
TABLE 12
REACTION HOUR TOTAL PRESSU~E OF Hg RATE OF DECHLORINATION
(hour) (kS / cm ) (%)
0 31.3 0.0
0.5 32.1
1 32.1
1.5 32.1
2 32.1
2.5 32.1
3 32.1 1.26
No pressure drop was recognized, but it was found by an ignition
test that the catalyst maintained its activity after the rection was
finshed. This test shows that without the use of an emulsifying-
dispersing agent a dispersion required for effecting the reaction
cannot be developed as long as the temperature remains 100C or around.
EXAMPLE 9
The hydrogenation-dechlorination reaction was effected in the
same manner as Example 8, except for the use of a PCB having 5 chlor~des,~
.0 ~ ~/~r ~r
on an average. 6.80g ~0.105 gram equivalent weight) of the PCB (KC-500~)
was used. The results are shown in Table 13:
TABLE 13
Reaction temperature: 100C
REACTION HOUR TOTAL PRESSU~E OF Hg RATE OF DECHLORINATION
(hour) (kg / cm ) (%)
0 30.9 0.0
0.5 ' 26.0
2?~2
1.5 20.0
2 18.0
2.5 16.0
3 15.3 83.7
_ 16
10'3'~ 0
; ,
.. . . , . . . . . . . .. _
Twenty-four hours after the reaction was finished, an ignition
test was conducted upon the Raney nickel catalyYt, and it was found
that it ignited in the same manner as before the reaction, which shows
that its catalytic activity was maintained after the reaction.In addition,
it was ascertained through a gas chromatography and a gas chromatography-
mas~ spectrometry that a great amount of biphenyl and a small amount
of bicyclohexyl had been produced.
EXAMPLE 10
The hydrogenation-dechlorination reaction was effected in the
same manner as Example 8, except for the use of a PCB having 6 chlorides
on an average. 6.29g (0.105 gra~ equivalent weight) of the PCB was used.
The results are shown in Table 14:
TABLE l4
Reaction temperature: 100C
REACTION HOURTOTAL PRESSU ~ OF Hg RATE OF DECHLORINATION
(hour)(kg / cln ) (%)
0 31.4 0.0
-5 31.0
1 27.3
1.5 25.0
2 22.5
2.5 20.2
3 17.9 74-~15
Twenty-four hours after the reaction was finshed, it was found
by an ignition test that the catalyst maintained its activity, and
additionally it was ascertained through a chromatography and a gas
chromatography-mass spectrometry that a great amount of biphenyl and
a small amount of bicyclohexyl had been produced.
EXAMPLE ll
The hydrogenation-dechlorination reactions were effected, u~ing
- 17
103`~S~0
.
'
a PCB having 10 chlorides on an average, at 160 C, (1) with 40ml of
isopropyl alcohol and (2) with 30ml thereof for a dispersing agent.
The results of these two reactions are shown in Tables 15 and 16,
respectively. The other conditions were the same as Example 8. But
under the use of 30ml of the agent the reaction was continued for 4 hours.
TABLE 15
Reaction temperature: 160C Dispersing agent: 40ml Reaction hour: 3hr
REACTIQN HOUR TOTAL PRESSU ~ OF Hg RATE OF DECHLORINATION
(hour)(kg / cm ) (%~
28.5 0.0
-5 26.9
1 23.7
1.5 21.2
2 Ig.9
2.5 18.9
3 18.7 82. 6fi
After the reaction was finished, it was found that the Raney
nichel catalyst had been reduced in size to grains of 1 to 3mm, and
after the same was cleansed with ethyl alcohol, an ignition test
showed that it maintained its catalytic acti~ity though it slightly
lowered. It has also beenascertained through a gas chromatography and
a gas chromatography-mass spectrometry that a great amount of biphenyl
and a small amount of bicyclohexyl had been produced.
TABLE 16
Reaction temperature: 160C Dispersing agent: 30ml Reaction hour: 4hr
REACTION HOUR TOTAL PRESSU~E OF llg RATE OE DECHLORINATION
(hour)(kg / cm ) (~/o)
33.8 0.0
0.5 28.9
- lo
1()~?~580
. . ~
1 26.1
1.5 23.0
2 21.3
2.5 21.0
3 21.0
3~5 20.9
4 20.9 91.86
After the reaction was finished, it was found that the catalyst
had been also reduced in size to grains, but that its catalytic
activity remained though it slightly lowered, which was ascertained by
an ignition test. It was also found through a gas chromatography and
a gas chromatography-mass spectrometry that a great amount of biphenyl
and a small amount of bicyclohexyl had been produced.
EXAMPLE 12
Instead of the Raney nickel catalyst in Example 8 250mg of carbon-
supported palladium catalyst (10%) was used to effect the hydrogenation-
dechlorination reaction, in which the reaction was continued for
2 hours and a half. The results are shown in TABLE 17:
TABLE 17
Reaction temperature: 100C
REACTION HOUR TOTAL PRESSU~E OF Hg RATE OF DECHLORINATION
(hour) (kg / Cm ) (% )
3-5 0.0
0.25 12.9
0.5 11.2
1.0 9.6
1.5 8.2
2.0 7.2
2.5 6.~ 100.0
It was ascertained through a gas chromatosraphy and a gas
_ ~9
5~0
chromatography-mass spectrometry that the PCl3 had been c)nverted into
a great amount of biphenyl and a small amount of bicyclohexyl.
.
EXAMPLE 13
7.65g of PCB (KC-400) having 4 chlorides on an averase (0.105
gram equivalent weight), 6.18g of potassium hydroxide (0.105~ram
equivalent weight), and 30ml of ethyl alcohol for a dispersing agent
were mixed, and the hydrogenat~on-dechlorination reaction was effected
under a 30kgw/cm total pressure of hydrogen and with lOOmg of a
carbon-supported palladium catalyst (10%~. The reaction was carried
out at 100C for 2 hours and a half, the results of which are shown
in Table 18;
TABLE 18
REACTION HOUR TOTAL PRESSUR~ OF HS RATE OF DECHLORINATION
(hour)(kg / cm ) (%)
0 29.9 0.0
0.2525.3
0.520.1
1 16.9
1.516.4
2 16.1
2.5 15-9 86.o
It wa~ found through a gas chromatography and a gas chromatograph-
mass specrometry that the products contaihed a great amount of biphenyl
and a small amount of bicyclohexyl.
EXAMPLE 14
The hydrogenation-dechlorinQtion reaction was effected in the
same manner as Example 8, except for the use of 500mg of 5~0 platinum
car~on, the result~ of which are shown in Table 19:
~() _
iO~9~S80
_ . . . , ,, . _
TA~LE 19
REACTION HOUR TOTAL PRESST2RE OE llg RATE OF DECHLORINATION
(hour) (kS / cm ) (%)
o 32.8 0.0
0.5 31.9
1 30.o
1.5 3~-
2 29.1
2.5 28.2
3 27.2 25.4
It was found through a gas chromatography and a gas chromatography-
mass spectrometry that the products contained a great amount of biphenyl
and a small amount of bicyclohexyl.
EXAMPLE 15
This experiment is a modification to Example 8 in which the
m~xing ratio of isopropyl alcohol and water was changed. The results are
depicted by the graph in FIGURE 1. It was found that with the use of
lOml of isopropyl alcohol the decomposition rate was not sufficient
irrespective of the remaining catalytic activity. Even in the case of
a PCB having 3 chlorides the decomposition rate did not remarkably im-
3 hour
prove during the~reaction.When the dispersing agent is added more than
water (exceeding 50ml), the decomposition rate becomes worse, and
when it amounts to 70ml, an alkaline decomposition only occurs, in which
the PCB will be found slightly in brown.
EXAMPLE 16
In this experiment the amount of sodium hydroxide in Example 8
was variously changed, the results of which are depicted by the graph
in FIGURE 2.
The graph shows that the decomposition rnte fnlling in the
range of 0.75 to 1.25 equivalent weisht ratio to PCB is bctter thnn
in other ranges. Under the conditions of Example ~, Whell the ratio
~0~580 ;
.
of sodium hydroxide equivalent weight to PCB is not grsater than 1,
the rate of dechlorination is almost equal to the ratio of equivalent
weight, from which it is understood that the reaction accelerateS in
the zone ranging from the point of neutralization to the acid zone.
In this case, after the reaction is finished, the catalyst loses
its activity.
When the ratio is greater than 1, the rate of dechlorination
becomes equally worse; when it is up to 1.25 or around the rate of
dechlorination still exceeds 50%, but when the ratio is greater than
1.25, it adversely affects the decomposition. The catalytic activity
is maintained when the ratio of sodium hydroxide equivalent weight to
PCB ranges from 1 to 2.
In a mixture of water and isopropyl alcohol (mixing ratio: about
2 to 1) the optimum concentration of sodium hydroxide is lN, and it
is understood that it is closely connected with the fact that when
the concentration of alkali is less than lN, a good dispersion is
resulted.
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