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Патент USA US3079423

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3,@?§,?il3
Patented Feb. 26, E953
1
2
3,ll79,4l3
esters appear to produce a number of ditferent reaction
METHOD OF PRODUQENG SHGRT CHAIN
METHYL ESTERS
Karl J. Moulton and Thomas ‘W. Findiey, La Grange, Ill,
and Vasiii I. Kornarewshy, deceased, late or Qhicago,
lib, by Jessie B. Kornarewsity, executrix, Chicago, Ell”
designers to Swift 51 Company, Chicago, Ill., :1 corpo
ration of iilinois
No Drawing. Filed Eniy 5, 1966, Ser. No. 40,156
14 Claims. (Cl. ass-arcs)
The present invention relates in general to a method
of producing short chain methyl esters. More specifically,
the invention is directed to a method whereby certain
products when subjected to vapor phase continuous re
action conditions.
More particularly, we have found that continuously
passing the vaporized methyl ester charge through a re
action zone which will maintain vapor phase reaction con
ditions in the charge will cause cleavage along the carbon
chain of the charge to produce shorter chain methyl esters
as a product of the thermal treatment. The reaction vessel
is preferably constructed of a material nonreactive with
the charge, e.g., stainless steel, quartz, glass, etc. An
apparatus such as that disclosed and claimed in US.
Patent No. 2,952,527 to Findley et al., is eminently suit
long chain aliphatic esters are handled in such a manner
able for carrying out this reaction. However, any assem
that shorter chain esters are derived therefrom.
15 blage which can heat the est-er charge sufficiently to
Short chain methyl esters are useful as intermediates
vaporize it and then substantially immediately pass the
in forming other compounds, can be hydrolyzed to form
vaporized charge into a reaction zone which will main
the corresponding acid (many of which, particularly the
tain vapor phase reaction conditions in the charge is
unsaturated fatty acids of less than 10 carbons, are un
adaptable to our process.
observable in nature and/ or commercially unavailable), 20
The reaction zone is preferably but not necessarily
and have usefulness, either alone or in combination, as
packed to provide more heating surface therein for the
antirnycotic agents, larvicides, and nematocicles. It is
charge as it passes therethrough. This packing can be
therefore evident that a method for preparing these sub
an inert material or a material catalytic to the reaction.
stances would be of bene?t in many industrial ?elds.
Glass beads are illustrative of a substantially inert pack
It has previously been observed that thermal treatment 25 ing substance. As an example of a catalytic packing
of higher aliphatic esters produces substantial decar
material we have found that packing the reaction zone
boxylation and dehydration with formation of ketones
with silica gel particles will catalyze the reaction to in
and hydrocarbons.
crease the percentage of shorter chain methyl esters
formed in the process and decrease the reaction time re
Other reports indicate that the pre
dominant reaction upon pyrolysis of unsaturated C18 fatty
acid esters is polymerization, with 60—70% yields noted.
Generally the reported prior work has involved batch
quired. The vaporized fatty ester charge is preferably
pyrolysis at temperatures of from about l70—400° C. for
extended periods of at least several hours.
of low boiling liquid which is substantially unreactive with
the charge. Illustrative of such substantially unreactive
swept into the reaction zone by means of a gas or vapor
It is an object of our invention to provide a method
sweep gases are nitrogen, carbon dioxide, steam, and the
of handling higher aliphatic esters in such a manner that 35 like. Reactive gases, such as oxygen, may also be used
there is not extensive polymerization or decarboxylation
in the reaction. Speed at which the sweep gas carries
(as evidenced by carbon dioxide make) and little forma
the charge into and through the reaction zone will be
tion of hydrocarbon gas or carbonization.
described more fully hereinafter.
It is a further object of our invention to provide a
The temperature in the reaction zone and the methyl
method for handling long chain methyl esters such that 40 ester charge as it is continuously swept therethrough
shorter chain methyl esters rather than acids and their
should be in the range or" about 8G0—1100° F. Tempera
thermal degradation products are formed.
tures below about 800° require too extensive a reaction
An additional object of our invention is to provide a
time and ‘approach batchwise conditions with attendant
method for directing the pyrolysis reaction of long chain
decarboxylation. Temperatures ‘above about 11%" F.
45 are generally not required to maintain continuous vapor
methyl esters to produce shorter chain methyl esters.
Further objects and advantages of our invention will
phase reaction conditions. The charge is passed into the
occur to those skilled in the art from a reading of the
following description of our invention.
We have discovered that by subjecting unsubstituted
higher methyl esters to vapor phase continuous reaction
conditions shorter chain methyl esters are produced with
out extensive carbon dioxide make, hydrocarbon gas make,
polymerization, or carbonization.
Both saturated and
unsaturated methyl esters will cleave along the alkyl
zone at such a rate that it exits the zone after remaining
therein between about .5-70 seconds, and preferably
about 20-40‘ seconds. The rate at which the charge is
passed into the zone can more conveniently be spoken of
in terms of the space velocity of the charge into the zone.
“Liquid space velocity” is a general term used in the
petroleum cracking industry and refers to the relative
volume of liquid feed passing through a volume of re
chain when subjected to our manner of handling. When 55 action zone per unit time. In our method liquid space
working with the unsaturates cleavage occurs at various
velocities between about 0.4 and 5 may be used. If, for
points along the chain as evidenced by production of
example, the reaction zone volume is 200 cc. and the
several fractions from one cracking procedure having
space velocity of 0.6 is chosen, 200 times 0.6 or 120 cc.
substantially varying molecular weights and boiling point
of ester charge would be passed through the reaction zone
ranges. Generally we produce methyl esters ranging in 60 per hour.
chain length from C3 to the chain length of the starting
The reaction time, that is, time that the vaporized
material. Regardless of the degree of saturation in the
charge remains in the reaction zone, should preferably be
long chain methyl ester charge, unsaturation appears in
the shorter chain methyl esters produced.
varied inversely with the temperature maintained in the
zone. We have found that the reaction will proceed ap—
It appears that the unsubstituted methyl esters are 65 proximately 50 times faster for each lii0° F. increase in
unique in that esters of the longer alkyl radicals or alkyl
temperature. For example, if the reaction takes 20
aryl radicals cleave in such a manner that little or no
seconds at 1000" F., it should take only about .5 second
shorter chain ester remains. The substituted methyl
at 1100° F. The pressure within the zone should be so
3.07am
3
correlated with the temperature, nature of the charge,
4
methyl esters, little decarboxylation, and that the pure-
acted feedstock fraction was unaffected by the severe
and reaction time as to maintain the charge in the vapor
heat. Infrared absorption and mass spectrograph indi
phase. It is therefore possible to use negative pressure
cated the products to be mixtures of terminally unsaturated
(i.e. vacuum) conditions. Positive pressures up to about
methyl esters and hydrocarbons, with the corresponding
3 atmospheres may be used, depending upon the other
terminally saturated substance.
variables, when using a reaction vessel of the type dis
closed'in the‘ aforementioned Patent No. 2,952,527.
EXAMPLE II
' As previously mentioned, the starting materials which
Redistilled methyl palmitate charge was pumped from
we have discovered can be thermally treated continuously
a graduated cylinder into a vessel substantially corre
in the vapor phase to yield short chain methyl esters are 10 spondingto the vessel disclosed and claimed in US. Patent
the unsubstituted methyl aliphatic esters. Saturated and
No. 2,952,527, the reaction zone of which was packed
‘unsaturated methyl esters of fatty acids having a chain
with 5mm. diameter glass beads, at a liquid space velocity
length of from 10-24 carbons are useful in our method.
of 0.9 cc. charge per cc. packing per hour. One mol
Specific examples of suitable starting materials include,
nitrogen per mol of charge pumped entered the vessel
but are not limited to, the unsubstituted methyl esters of 15 and swept the charge, vaporized by heat, over the packing
capric, lauric, myristic, palmitic, stearic, arachidic, be
henic, oleic, palmitoleic, petroselenic, vaccenic, erucic,
gadoleic, elaidic, ‘unde'cylic, undecylenic acids, and mix
in the reaction zone. The reaction zoneand charge were
maintained at a temperature of 1050° F. —_i—5° F. At this
rate of ?ow the charge will remain in the reaction zone
for approximately 25 seconds and ‘will then be dis
methyl esters of ethanoid and monoethenoid acids since 20 charged from the zone and the discharged products per
polyethenoid acid esters yield polymeric products unless
mitted to ?ow through a condensing system which allowed
tures of these esters. We prefer to use the unsubstituted
rigorous precautions‘ are taken to prevent this, such as op
erating at extremely short reaction times.
the liquid to collect in a tared receiver and the non
condensable gas to pass through a gas meter and gas col
After continuously passing the charge through the vapor
lecting vessel.
Representative samples of the noncon
phase reaction zone, we collect the products of the reac 25 densable gas were collected and analyzed for carbon
tion, condense the condensable portion thereof, and sep
arate the unreacted charge from the low boiling short
change methyl esters and the hydrocarbons (both of which
dioxide, ole?n, and paraf?n using published methods.
is useful as an intermediate and can be used as is for some
purposes, e.g., as a moldicide. ‘If it is desired to use the
84.0% total liquid recovery (by weight)
173.8% shorter chain methyl esters
2.4% methyl acrylate
The recovered liquid was separated, fractionated, and an
alyzed. The following data were found:
we have invariably found to contain terminal unsatura
30
Table 1
ti-on) . This mixture of short chain esters and hydrocarbons
mixture, no further separation is required.
However,
further separation can be effected either by means of a
1.0% ester of average mol. wt. of 112
10.4% ester of average mol. wt. of 191
saponi?cation reaction to remove the hydrocarbon or by
means of silica gel chromatography, a system'which’ ad
sorbs the ester and permits the hydrocarbon to pass
9.0% cracked hydrocarbon
3.4% of B1’. <50° C. at 5 mm. Hg
through. The soaps formed are useful as such for certain
5.6% of BF. 50—166° C. at 5 mm. Hg
purposes, for example, as mold inhibitors. We can then
54.7% unreacted charge (methyl palmitate)
fractionate the ester portion into constant boiling com 40
6.5% polymerized (residue)
ponents to determine the range and amount of the various
15.9% gas make recovery (by weight), or 1.23 mols/mol
esters.
As an aid to classifying the esters we can com
charge
pare their boiling points with known data. There is but
a slight difference in boiling points of saturated and un
'
0.07 mol Cog/mol charge
0.86 mol ole?n/mol charge
saturated methyl esters. As has been mentioned we have
0.30 mol paraffin/mol charge
found unsaturation in the shrot chain methyl esters in all
0.1% carbon (by weight) deposited on packing
cases as evidenced by infrared absorption. In cases'where
We have found methyl esters of all of the. terminally
boiling point data is insu?icient to identify the ester, other
unsaturated
acids up to C12 acids in the cracked portion
known means, such as saponi?cation number, iodine
of the methyl palmitatc feedstock. Examples are methyl
value, molecular weight, solubility, 'etc., are used. The 50 acrylate, methyl B-butenoic acid, methyl 4-pentenoic acid,
unreacted charge can then be recycled through the system
etc., up to, methyl ll-dodecenoic acid. There is also
to effect another vapor phase reaction with cracking of the
iodine number evidence to the fact that a portion of the
charge resulting. We prefer that only 50% or less of the
methyl esters are of saturated acids, probably of butyric
charge is cracked on one run, and preferably about
and higher acids.
20-40%. When higher percentages of cracked product
A run identical to that set out above, except that the
temperature was 850° F., was made wherein 1.25 mols
oxygen was2 metered into the reactionzone in a manner
are formed, further cracking may occur; when lower per
centages are formed, the yield may be impractically low.
The following examples are considered illustrative only
such that it did not mix with the vaporized methyl palmi
tate charge until they reached the reaction zone. 24.1%
and should not be construed as limiting upon the scope
of our invention.
' '
‘
EXAMPLE 11
Two samples of methyl Oleate feedstock were vaporized
by heating to vaporization temperatures. One sample was
swept by carbon dioxide gas carrier into a glass reactor
packed with glass beads. In the other sample steam was
00
condensablev cracked. product and 67.5% unreacted charge
resulted. On gas analysis, no free oxygen was found.
4.5% water was'formed and some hydrogen gas. This
run indicates that the reaction temperature can be lowered
when oxygen is used in the reaction.
. usedas the sweep gas. The feedstock was passed through
the reactor at a liquid space velocity of 0.5. Temperature
was maintained at 1000°—1050°j F. The products of the
EXAMPLE III
Three vaporized charges of methyl palmitateand three
of methyl oleate were continuously swept through a vapor
vapor phase reaction were collected in each run and the
phase reaction zone maintained at 1050" F. and 1000° F.
condensed liquid product fractionated under reduced pres:
sure to determine the ratio of cracked, 'unreacted, and
polymerized components. Methanol determination of the
fractionated products conclusively‘ showed that cracking
respectively. The. sweep gases were nitrogen, carbon di
oxide, and'steam. The packing material was glass beads.
Aj's'pace velocity of about 1 provides for approximately
22 seconds’. time in the reaction zone, while the space
velocity of 0.4 provides for approximately 70 seconds in
had occurred along'the carbon chain. Analyses showed
that the product components consisted of shorter chain 75 the zone. The following results were noted‘.
3,079,413
6
Table 2
Feedstock __________________________________ __
Methyl oleate
Temperature _______________________________ .-
1,000° F.
Sweep gas __________________________________ __
N2
Mols gas/mo] feed___
Space velocity_____
002
0.3:1
0. 4
Product analysis (weight percent):
Gas __________ __
}
short chain methyl esters and hydrocarbons, and separat
ing the short chain products from the unreacted unsub
10 stituted methyl esters.
5. 7
2. The method of causing cleavage along the carbon
9. 7
1:1
1
7. 4
47
8. 8
31
6
4. 5
74. 0
5. 3
4.2
72. 2
8. 2
0
0.1
0
Carbon deposited _______________________ __
collecting the condensable reaction products including
Steam
1:1
1
15
Cracked ester-_____
Cracked hydrocarbon
Unreaeted feed..__
Polymerized___
We claim:
1. The method of producing a mixture of short chain
methyl esters and hydrocarbons which comprises: react
ing unsubstituted methyl esters of higher fatty acids in
the vapor phase at a temperature above the vaporiza
tion temperature of the esters but below about 1100° F.,
Feedstock __________________________________ __
Methyl palmitate
Temperature _______________________________ __
1050° F.
chain of an unsubstituted methyl ester of a higher fatty
acid to produce shorter chain methyl esters which corn
prises: continuously passing a vaporize-d charge of said
15 unsubstituted esters through a reaction zone maintained
at a temperature between about 800° F.-1100° F. at a
space velocity of said charge of between about 0.4 and
5 and at a pressure so correlated with the temperature
and nature of the charge as to maintain said charge in
Sweep gas __________________________________ __
N2
Mols gas/mol feed _____ __
Space velocity ____ __
CO2
Steam
1 :1
1 :1
1 :1
1
1
1
Product analysis (weight
Gas _________ __
_
Unreacted feed_
Polymerized__
Carbon depos
____ __
______ __
________________ __
15. 9
17.0
16.0
13.8
12. 5
15. 2
9. 0
54. 7
6.5
0.1
a. s
54. 0
6. 9
0
10.5
58. 5
9. 8
0
20
the vapor phase whereby reaction products including
short chain methyl esters will be formed, and collecting
said reaction products.
3. The method of producing short chain methyl esters
which comprises: continuously passing a vaporized
charge comprising unsubstituted methyl esters of higher
fatty acids through a reaction zone maintained at a tem
perature of between about 800-1100" F. at a space ve
locity of said charge of between about 0.4 and 5 and at a
pressure so correlated with the temperature as to main
EXAMPLE IV
30 tain said charge in the vapor phase ‘whereby said charge
Methyl palmitate was run through continuous vapor
is thermally reacted to produce reaction products includ
phase reaction conditions following substantially the same
procedures as outlined in Example III except that the
reaction zone was packed with silica gel. The following
ing low boiling short chain methyl esters and hydrocar
bons, collecting said reaction products, condensing the
condcnsable portion thereof, and separating the low boil~
data were obtained:
ing products from the unrcacted charge.
Table 3
4. The method of producing methyl esters which corn
prises: continuously vaporizing a liquid charge compris
Feedstock ________________ ._
Temperature _____________ ._
Sweep gas ________________ __
ing unsubstituted methyl esters of fatty acids containing
10-24 carbons, continuously passing said vaporized
Methyl palmitate
1,000° F.
N2
002
40 charge under such pressure and at such a space velocity
through a reaction zone maintained at a temperature
1,050° F.
Steam
N:
CO2
Steam
above the vaporization temperature of the esters but be
low about 1100° F. to cause a vapor phase reaction in
Mols gas/moi feed _________ __
1:1
1:1
1:1
1:1
1:1
1:1
Space velocity ________ -__-___
1
1
1
1
1
1
24. 0
Product analysis (weight
so t :
per asril ________________ -_ 10.9
8. 7
10. 8
22. 0
18. 5
Cracked ester _________ __
13.0
11.6
35. 2
40. 3
13.1
Cracked hydrocarbon.--
6. 2
4. 5
9. 8
12. 3
8. 9
17. 7
Unrcacted feed ________ __ 68. 2
69. 0
40. 3
22. 2
53.0
41. 8
7.0
0.1
3.8
0.2
3. 5
0.3
6. 3
0.2
2. 8
0.2
Polymerized ____ __
__
Carbon deposited _____ __
1.6
0.1
13. 3
EXAMPLE V
said zone, collecting the products of said reaction and
removing low boiling methyl esters therefrom.
5. The method of producing terminally unsaturated
methyl esters having 2-15 carbons which comprises: con
tinuously vaporizing unsubstituted methyl esters of fatty
acids containing 10-24 carbons, continuously passing said
vaporized esters through a reaction zone maintained at a
temperature between about 800-1100" F. at a space ve
locity of said vaporized esters of between about 0.4 and 5
Methyl palmitate was continuously swept by nitrogen
gas through reaction zones maintained at various tem
peratures and with and without packing. The procedure
followed was substantially that of Example 11. The fol
lowing results were obtained:
Table 4
and at a pressure so correlated with the temperature and
space velocity as to maintain said esters in the vapor
phase whereby said esters will cleave along the carbon
chain to produce terminally unsaturated methyl esters
having 2-15 carbons and ole?ns, collecting the reaction
products, condensing the condensable portion thereof,
and removing the cracked product from the unrcacted
00 esters in said condensed portion.
Reaction
temperature
Packing
Percent
Percent
ester
recovery
liquid,
liquid
cracked
6. The method of claim 5 wherein the vaporized esters
are passed through the reaction zone by means of a sweep
gas.
7. The method of claim 5 wherein the unsubstituted
Percent
gas
max.
900 ___________ -_
1,050_ _
Glass heads _________ --
(1
1,000 _________ -_
03
30
7
8l
30
19
89
19
11
Norm-The ester values are given as maximum because they may
contain some unreacted feedstock ester.
Obviously many modi?cations and variations of the
invention as hereinbefore set forth may be made without
departing from the spirit and scope thereof, and therefore
only such limitations should be imposed as are indicated
in the appended claims.
methyl esters of fatty acids containing 10-24 carbons are
selected from the group consisting of unsubstituted meth
yl esters of saturated and mono-unsaturated fatty acids.
8. The method of producing short chain methyl esters
which comprises: continuously vaporizing an unsubsti
70 tuted higher fatty acid methyl ester charge, sweeping
said charge immediately after vaporization into and
through a reaction zone containing a packing material,
said reaction zone being maintained at a temperature of
between about 800°-11'00° R, said charge being swept
75 through said zone at a space velocity such that said
' 8,079,418
8
charge will remain in said zone for between about .5 and
'70 seconds, said charge being at a pressure so correlated
with the pressure and size of said zone as to maintain
said charge in the vapor phase while in said zone, where
14. The method of producing short chain methyl esters
which comprises: con-tinuously'vaporizing a methyl ole
ate charge, sweeping said charge immediately after vapori
zation into and through a reaction zone maintained at
about 1050" F1, said charge being under about one at~
mosphere of pressure and being swept into said zone at a
by ,a portion of said charge will cleave along the carbon
chain thereof, collecting the reaction products and un
space velocity of about 1 whereby said charge will react
reacted charge as they exit said zone, and separating the
in the vapor phase to produce reaction products including
short chain methyl esters from said reaction products.
terminally unsaturated methyl esters having carbon chain
9. The method of claim 8 wherein the unsubstituted
10 lengths less than C18, and collecting said reaction prod
methyl ester is methyl palrnitate.
ucts.
10. The method of claim 8 wherein the unsubstituted
methyl ester is methyl oleate.
References Cited in the ?le of this patent
11. The method of claim 8 wherein the packing mate
UNITED STATES PATENTS
rial is catalytic to the cleavage reaction.
12. The method of claim 8 wherein the packing mate 15 1,991,955
Ralston ______________ __ Feb. 19, 1935
rial is silica gel.
1,991,956
Ralston _____________ __ Feb. 19, 1935
13. The method of producing short chain methyl esters
2,107,904
Pool _________________ __ Feb. 8, 1938
‘which comprises: continuously vaporizing a methyl pal
2,133,007
Ralston et al. ________ __ Oct. 11, 1938
mitate charge, sweeping said charge immediately after
2,145,802
Ralston et al. _________ __ Jan. 31, 1939
vaporization into and through a reaction zone maintained 20 2,145,803
at about 1050° F., said charge being under about one
2,145,804
atmosphere of pressure and being swept into said “zone at
2,807,633
a space velocity of about 1 whereby said charge will re
2,821,543
act in the vapor phase to produce reaction products in
2,882,300
cluding terminally unsaturated methyl esters having car 25
bon chain lengths less than C15, and collecting said re
action products.
'Ralston et al. ________ __. Jan.
Ralston et al. ________ __ Jan.
Wetroff et al. ________ __ Sept.
Ethen'ngton __________ __ Jan.
31,
31,
24,
28,
1939
1939
1957
1958
Perry et al. __________ __ Apr. 14, 1959
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