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Патент USA US3027420

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March 27, 1962
3,027,41 1
C. R. MURPHY
PROCESS FOR OXIDIZING A NORMALLY GASEOUS HYDROCARBON
Filed June 22, 1959
BY
WL
f.
1C@
1
2
3,027,411
Research ¿it Development Company, Pittsburgh, Pa., a
corporation of Delaware
Filed .lune 22, 1959, Ser. No. 821,969
6 Claims. (Cl. 260-604)
This invention relates to a process for the controlled 10
product distribution.
Normally gaseous hydrocarbons can be subjected to
partial oxidation to produce a mixture of oxygenated
products having a lower carbon number than the hydro
carbon charge. While a large variety of oxygenated
products are obtained in such oxidation, the principal
ones produced are formaldehyde, acetaldehyde and
methanol. Care must be taken in such oxidation to main
Patented Mar. 27, 1962
square inch gauge, preferably about 100 to about 150
pounds per square inch gauge. Normally the amount
of time required to obtain the desired temperature rise
in the preheater is about 0.1 to about 2.0 seconds, pref
erably about 0.75 to about 1.5 seconds. The purpose of
the preheater in this type of oxidation reaction is to raise
Paocnss ron oxrnizING A NoRMALLY
ohsnous HvnnocAanoN
Clarence R. Murphy, Allison Park, Pa., assigner to Gulf
oxidation of normally gaseous hydrocarbons and more
particularly to a process for the controlled oxidation
of normally gaseous hydrocarbons to obtain a desired
3,027,411
the temperature of the bulk of the gas stream to reaction
temperature and to allow for an induction period to
occur prior to the onset of the oxidation reaction.
In accordance with the process of this invention, the
preheated recycle gas as it leaves preheater 4 by line
6 is admixed with a mixture containing the same normal
ly gaseous hydrocarbon being recycled and oxygen from
line 8. The hydrocarbon can be ethane, propane, butane
or mixtures thereof. The mixture in line 8 is not pre
heated and is at a temperature of about 60° to about 100°
F., preferably about 75° to about 100° F., and a pres
sure of about 0 to about 200 pounds per square inch
gauge, preferably about 100 to about 150 pounds per
square inch gauge. The amount of gaseous components
added to line 6 from line 8 is normally dependent upon
tain the oxygen-hydrocarbon ratio in the charge below
the
ratio of gaseous hydrocarbon and oxygen desired in
the explosive limits for this type of mixture. This can
the ñnal charge mixture. Referred to the pressure and
be done, for example, by employing air as the oxidizing
temperature of the preheated recycle hydrocarbon gas,
medium, the nitrogen in the air serving as a diluent. The 25
the
amount of fresh hydrocargon gas introduced therein
presence of nitrogen in the system, however, causes an
by line 8 is about 2 to about 12, preferably about 4 to
additional complication to an already complex product
about 6 percent by volume, and the oxygen introduced
recovery system and additionally contributes to vapor
therein
about one to about 6, preferably about 2 to
losses of the important oxygenated products produced in
about
4,
percent by volume based on the preheated
the oxidation process.
recycle gas in line 6. The resultant mixture in line 6
This diñiculty can be avoided by employing substan
is at a temperature of about 550° to about 750° F. pref
tially pure oxygen as the oxidizing medium in the proc
ess. In order to avoid the explosive limits for this type
of reaction, the amount of oxygen introduced into the
oxidation reactor relative to the normally gaseous hydro
carbon must be maintained low. Even when all of the
oxygen introduced into the reactor is consumed, a large
amount of unreacted hydrocarbon is removed from the
reaction zone with the oxygenated products. This, of
erably about 650° to about 700° F., and a pressure of
about 0 to about 200 pounds per square inch gauge,
preferably about 100 to about 150 pounds per square
o inch gauge.
The resultant gaseous mixture, in line 6 is thereafter
passed to reactor 10 wherein the partial oxidation re
action takes place. In order to consume all of the oxy
gen
in the gaseous mixture being introduced into re
40
course, necessitates the separation of a large amount of
actor 10 and at the same time reduce the amount of
hydrocarbon from the oxygenated products and the re
decomposition and degradation products in the desired
cycle thereof to the reaction zone. This can be done,
oxygenater product, the temperature of the reaction
therein is desirably maintained at about 650° to about
bon and oxygen to obtain the desired hydrocarbon 45 850° F., preferably about 650° to about 750° F., the
pressure about 0 to about 200 pounds per square inch
oxygen ratio in the charge. The resultant charge is then
gauge,
preferably about 100 to about 150 pounds per
v preheated and passed to the oxidation Zone.
square inch gauge, and the contact time, at such condi
I have found that a desired product distribution favor
tions, about 0.1 to about 2 seconds, preferably about
ing the formation of formaldehyde over acetaldehyde can
0.5 to about one second.
be obtained in such process by preheating the unreacted 50
The oxygenated products are removed. from reactor
hydrocarbon recycle gas, adding to the preheated un
10 by line 12 and within about 0.1 to about 2 seconds
reacted recycle hydrocarbon gas a mixture containing
are cooled to a temperature of about 250° to about 500°
fresh hydrocarbon gas and oxygen so that the resultant
F., preferably about 300° to about 350° F., and a pres-`
mixture contains hydrocarbon gas and oxygen in a pre
sure of about 0 to about 200 pounds per square inch
determined ratio and thereafter charging said resultant 55 gauge,
preferably about 100 to about 150 pounds per
mixture to an oxidation zone to obtain an oxidized mix
square inch gauge, lby passing the same through heat ex
ture comprising formaldehyde, acetaldehyde and meth
changer 14 or any other suitable means. The cooled
anol. By operating in accordance with the process of
product in line 16 is thereafter passed to any suitable or
this invention the formation of formaldehyde relative to
60 conventional recovery means to recover and separate the
acetaldehyde is favored.
desired oxygenated compounds, such as formaldehyde,
The process of this invention can be further illustrated
acetaldehyde
and methanol, `and unreacted hydrocarbon
by reference to the accompanying llow diagram. A nor
therefrom. The recovered unreacted gaseous hydrocar
mally gaseous hydrocarbon recycle gas in line 2, which
bon is recycled by means of line 2. Desirably, the re
can be at a temperature of about 100° to about 700° F., 65
covered unreacted gaseous hydrocarbon gas is iirst passed
preferably about 600° to about 650° F., and a pressure
by line 18 through heat exchanger 14 for the purpose
of about 0 to about 200 pounds per square inch gauge,
previously defined prior to recycling by line 2.
preferably about 100 to about 150 pounds per square
The following examples illustrate the fact that reaction
inch gauge, is passed through preheater 4 wherein the
conditions remaining constant, the distribution of form`
recycle gas is raised to a temperature of about 600° to 70 aldehyde and acetaldehyde in the oxygenated product
about 800° F., preferably about 650° to about 750° F.,
is profoundly affected by the point of addition of fresh
and a pressure of about 0 to about 200 pounds per
gaseous hydrocarbon and oxygen to the system.
for example, by recycling the unreacted hydrocarbon
and combining therewith suiiicient additional hydrocar
3,027,41 1
3
4
reacted gaseous hydrocarbon, separating unreacted gas
eous hydrocarbon from said oxygenated product, preheat
EXAMPLE I
70 cubic feet of recycle gas at a temperature of 625° F.
ing said unreacted gaseous hydrocarbon to a temperature
and a pressure of 160 pounds per square inch gauge ana
of about 600° to about 800° F. and a pressure of about 0
lyzing 70 percent by volume propane and 30 percent by
volume of methane, ethane, carbon monoxide, carbon
to about 200 pounds per square inch gauge, admixing with
said preheated gaseous hydrocarbon fresh gaseous hydro
dioxide and nitrogen were admixed with 6.3 cubic feet
carbon and oxygen, and thereafter subjecting the resulting
of a fresh mixture containing 70 percent by volume of
mixture to the aforesaid oxidation reaction, whereby the
propane and 30 percent by volume of oxygen, said latter
ratio of formaldehyde to acetaldehyde produced is in
mixture being at a-_temperature of 100° E. and 100 pounds 10 creased.
per square inc_h gauge. The resutlant mixture was pre
12. The process of claim 1 wherein the normally gaseous
heated tç a temperature of 650° F. and a pressure of 100
hydrocarbon is propane.
pounds per square inch gauge and then reacted at a tem~
perature of 775° F. and a pressure of 100 pounds per
3. A process for oxidizing a normally gaseous hydro
carbon which comprises subjecting said hydrocarbon in
square inch gauge for 0.75 seconds. After cooling the
products to a temperature of 325° F. within one second,
the oxygenated products were sent to a recovery and sepa
ration system.
admixture with oxygen to oxidation at a temperature of
about 650° to about 850° F. and a pressure of about 0
to about 200 pounds per square inch gauge for about 0.1
to about 2 seconds to produce an oxygenated product
EXAMPLE 1I
predominating in formaldehyde and acetaldehyde and un
In this run, which was carried out in accordance with
20 reacted gaseous hydrocarbon, separating unreacted gase
the process of this invention, the conditions of Example I
were maintained with the exception that the fresh mix
ture of propane and oxygen was added to the recycle pro
pane gas after the latter had been preheated to the stated
ous hydrocarbon from said oxygenated product, preheat
ing said unreacted gaseous hydrocarbon to a temperature
of about 600° to about 800° F. and a pressure of about
0 to about 200 pounds per square inch gauge, adrnixing
with said preheated gaseous hydrocarbon about 2 to about
temperature. The results obtained vin Examples í and II 25 12 percent by volume of fresh gaseous hydrocarbon and
are ,set forth below in Table I.
about one to about 6 percent by volume of fresh oxygen,
and thereafter subjecting the resulting mixture to the
aforesaid oxidation reaction, whereby the ratio of formal
30 dehyde to acetaldehyde produced is increased.
Example I Example II
4. The process of claim 3 wherein the normally gase
Table I
Products, Wt. Percent
Formaldehyde ..... _.
. ____ ._
26. 3
33. 4
Acetaldehyde ______ _.
ous hydrocarbon is propane.
5. A process for oxidizing a normally gaseous hydro
_
30. 7
24. 8
_
23. 3
22. 1
carbon which comprises subjecting said hydrocarbon in
__________ __
2.3
2.3
admixture with oxygen to oxidation at a temperature of
Others 1 _____________________________________ -_
17. 4
17. 4
Methanol _.
Acetone_____
____
t1 _0_2 to C4 alcohols, acetone, dimethyl acetal, methyl formate, Ymcthylal,
e c.
A study of the data in Table l reveals the fact that
the mere expedient of introducing the fresh gaseous hy
drocarbon and oxygen into the system after the recycle
hydrocarbon gas has been preheated to reaction tempera
ture, and not before, results in a signiñcant change in the
nature of the oxidation product obtained. Note that this 45
expedient results in an increase of formaldehyde from
26.3 to 33.4 percent by weight and a decrease in »the per
cent of acetaldehyde from 30.7 to 24.8 percent by weight.
Since the amount of methanol in each case is about the
same, the increase in the amount of formaldehyde ob
tained cannot be explained on the basis of the conversion
of methanol to formaldehyde.
Obviously many modifications and Variations of the in.
vention, as hereinabove set forth, can be made without
departing from the spirit and scope thereof, and there
about 650° to about 850° F. and a pressure of about O
to about 200 pounds per square inch gauge for about
0.1 to about 2 seconds to produce an oxygenated product
predominating in formaldehyde and acetaldehyde and un
reacted gaseous hydrocarbon, separating unreacted gase
ous hydrocarbon from said oxygenated product, preheat
ing said unreacted gaseous hydrocarbon to a temperature
of about 600° to about 800° F. and a pressure of about
0 to about 200 pounds per square inch gauge, admixing
with said preheated gaseous hydrocarbon about 2 to about
12 percent by volume of fresh gaseous hydrocarbon and
about one to about 6 percent by volume of fresh oxygen,
said fresh gaseous hydrocarbon and fresh oxygen being
at a temperature of about 60° to about 100° F. and a
pressure of about 0 to about 200 pounds per square inch
gauge, and thereafter subjecting the resulting mixture to .
the aforesaid oxidation reaction, whereby the ratio of
formaldehyde to acetaldehyde produced is increased.
6. The process of claim 5 wherein the normally gaseous
hydrocarbon is propane.
fore only such limitations should be imposed as are in
dicated in the appended claims.
`I claim:
1. A process for oxidizing a normally gaseous hydro
References Cited in the file of this patent
UNITED STATES PATENTS
admixture with oxygen to oxidation at a temperature of
about 650° to about 850° F. and a pressure of about 0
carbon which comprises subjecting said hydrocarbon in 60
`1,729,711
1,995,991
2,186,688
Curme ______________ __ Oct. 1, 1929
Lenher _____________ __ Mar. 26, 1935
Walker _______________ __ Jan. 9, 1940
to about 200 pounds per square inch gauge for about 0.1
2,365,851
Thomas ___ __________ __ Dec. 26, 1944
to about 2 seconds to produce an oxygenated product
predominating in formaldehyde and acetaldehyde and un
2,376,668
Derby ______________ __ May 22, 1945
2,570,215
Dice ___ ______ __________ Oct. 9, 1951
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