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Патент USA US2412823

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Dec. 17, ,1946.
a. J. MAYLAND
FURFURAL RECOVERY
Filed Feb. 8, 1945
o
2,412,823
Patented Dec. 17, 1946
' 2,412,823
UNITED STATES PATENT OFFICE
2,412,823
FURFURAL RECOVERY
Bertrand Jesse Mayland, Bartlesville, Okla., as
signor to Phillips Petroleum Company, a cor
poration of Delaware
Application February 8, 1945, Serial No. 576,849
9 Claims.
This invention relates to the recovery of fur
fural from admixture with hydrocarbons boil
_ing above the hydrocarbon for which the fur
fural has been used as an extraction agent, espe
cially from furfural-hydrocarbon mixtures from
which the furfural is not readily removable by
(Cl. 260-347) '
2
of the column.4 Through foaming and entrain
ment furfural may be carried overhead in the hy
drocarbon products from the extractive distilla
tion and stripper columns resulting in a loss of
furi'ural and contamination of the hydrocarbon
products.
'
‘
ordinary fractional distillation either because of
the formation of azeotropes or because of the
closeness of the boiling points of the furfural and
Various methods for removing these hydrocar
bon contaminants from furfural have been here
tofore disclosed. For example, the copending ap
hydrocarbons.
10 plication of Thodos and Weinaug, Ser. No. 546,
In the extractive distillation of unsaturated ali
371, filed July 24, 1944, discloses the use oi light
phatic hydrocarbons using furfural as the sol
hydrocarbons such as isopentane, normal pen
vent, especially in the recovery of oleñns and
tane, hexane, etc., in excess of their solubility in
dioleflns particularly normal butylenes and/or
furfural at some predetermined temperature.
butadiene, the furfural gradually becomes con 15 The light hydrocarbon and furfural are intimate
taminated with close-boiling hydrocarbons which
ly mixed and phase separation allowed to occur
are objectionable for a number of reasons. One
wherein a light hydrocarbon-rich and a furiural
diiîlculty caused by the presence of a substantial
rich phase are obtained. Most of the contami
amount of these oils in the furfural solvent is
nating hydrocarbons by reason of their greater
that they cause the furfural to foam in the eX-‘ 20 solubility in the light hydrocarbon remain in the
tractive distillation columns and in the strippers
light hydrocarbon phase. Thus a furfural-rich
thereby interfering seriously with their operation
and causing loss of valuable furfural overhead.
These hydrocarbon contaminants having boiling
phase relatively free of contaminating hydrocar
bons is obtained.
y
The copending application of Thodos, Ser. No.
points above that of the hydrocarbon for which 25 572,532, ñled January 12, 1945, shows a method of
the furfural is used as an extraction agent tend
removing both polymer and foaming oils from
to accumulate in the furfural, since they are not
furfural by extraction with light hydrocarbon
removed in conventional furfural re-running op
which leaves the polymer undissolved followed by
erations which are commonly conducted in ac
cooling of the extract phase of hydrocarbon and
cordance with U. S. Patents to Buell et al. 2,350, 30 furfural to effect separation into two layers,
584, and Hachmuth 2,350,699, and in Hachmuth
namely, a furfural layer relatively free of foam
copending application Ser. No. 460,874, filed Oct.
ing oils and a hydrocarbon layer containing most
5, 1942, such re-runnlng effecting only the re
of the foaming oils.
moval of polymer from the furfural in the sys
The copending application of Weinaug and
tem.
These hydrocarbons may enter the system from
valve, compressor, pump, etc., lubricating devices
and from traces of heavy hydrocarbons retained
Buell, Ser. No. 576,852, ñled February 3, 1.945,
shows a method of recovering furfural from ad
mixture with close-boiling oils by water extrac
tion with such an amount of water that all of the
in the feed to the extractive distillation step.
furfural can readily dissolve in the water at the
The hydrocarbon contaminants may comprise bu 40 temperature of extraction which preferably lies
tadiene cyclic dimer (4 - vinylcyclohexene-l')
between 90 and 150 degrees F. followed by azeo
formed in the extraction of >butadiene-containing
tropic fractional distillation of the water ex
streams. In time these hydrocarbons may ac
tract to give an overhead of the azeotrope of fur
cumulate to objectionably high concentrations
fural and water which upon condensation sepa
resulting in a decrease in the selectivity and ca 45 rates into two layers. By the use of an excess of
pacity of the furfural to function as a selective
water in the extraction step over that required to
solvent in the solvent extraction process for which
dissolve all of the furfural the loss of furfural
it is being used. Also, such hydrocarbon con
by its remaining dissolved in the hydrocarbon
taminants have a tendency to cause foaming in
phase is minimized and 'the necessity for the use
the extractive distillation and stripping steps. 50 of high temperatures which are objectionable is
Foaming decreases the eifectiveness of the fur
eliminated. The furfural being much more solu
fural for making the desired separation because
ble than the hydrocarbon in Water is selectively
foam from the lower part of the extractive distil
dissolved to give two phases, a hydrocarbon con
lation column will be entrained by the upwardlyl
phase and a water furfural-rich
rising vapors and carried into the upper parts 65 taminant-rich
phase. The present invention relates to an im
2,412,828
tion.
4
sitate excessively high pressures at the extrac
tion temperature in order to hold it in the liquid
phase, although the hydrocarbon contaminants in
the furfural exhibit considerable solubility for
provement over this method of water extrac
,
The hydrocarbon contaminant-rich phase in
all the foregoing cases will contain appreciable
amounts of furfural and the present invention is
particularly applicable for recovering the small
amounts of furfural remaining in the hydrocar
bon-rich phases from the above described proc
esses for purifying furfural in admixture with
close-boiling hydrocarbons. However, the process
of the present invention may be equally well
applied to the recovery of furfural by the water
extraction method before any such hydrocar
bon contaminant concentrate is prepared and in
the latter aspect it is an improved way of car
rying out the water extraction method.
The principal object of the present invention
is to provide an improved method of recovering
furfural from admixture with hydrocarbon' and
the propane so ‘that the pressure required to keep
the propane in solution in the liquid higher-boil
ing hydrocarbons is not as high as it would be to
maintain pure propane in liquid phase at the same
temperature. One advantage of a normally gase
ous material such as propane or butane is that
it can be very easily separated from the heavy
hydrocarbon-containing phase, In general, nor
mal pentane is most highly preferred as the light
hydrocarbon since it meets the foregoing require
ments or desiderata better than any other hydro
carbon.
.
Instead of a single light hydrocarbon, mixtures
of two or more of the foregoing hydrocarbons may
be employed.
For example, light straight-run
Ordinarily
particularly close - boiling hydrocarbons from 20 naphtha may be used in some cases.
it is preferred that a parailln be used and that it
be substantially free from oleñns, diolefins, naph
„ which it is diiiicult or impossible to separate the
furfural by distillation such as fractional distil
lation or steam distillation. Another object is to
provide an improved method of carrying out the
water extraction of furfural from such mixtures.
Another object is to provide an improved method
comprising water extraction followed by azeo
thenes and aromatics because these increase the
loss of furfural by reason of the greater solubility
f.
‘ tropic distillation of the water extract for recover
of furfural therein during the extraction, because
the unsaturates are not desirably inert, and be
cause .these hydrocarbons are too costly for the -
purpose at hand.
The amount of the light hydrocarbon employed
ing furfural from such mixtures. Another object
is to accomplish the foregoing objects in a simple 30 may vary within quite wide limits. In general,
.the weight ratio of light hydrocarbon to oils in
and economical> manner employing equipment
the oil-furfural mixture being extracted may
which is simple and not excessively expensive and
range from 10 to 1 to 100 to 1, a ratio of from 50
adapted to operation for long periods of time.
to 1 to 100 to 1 often being preferred.
Numerous other objects will hereinafter appear.
The amount of water employed may likewise
The accompanying drawing portrays diagram 35
vary widely depending upon a number of circum
matically one arrangement of equipment which
stances, as explained in the copending applica
may be used for carrying out the present inven
.tion of Weinaug and Buell'above-identifled. Fac
tion.
I have found that furfural containing hydro-1v ‘ tors affecting the weight ratio of Water to fur
fural in the oil-furfural mixture being extracted
carbon contaminants having higher boiling tem
include temperature of extraction, concentration
peratures than the hydrocarbon for which the
‘of furfural, degree of saturation of the water
furfural has been used as an extraction agent,
phase with furfural desired, etc. It is usually
especially hydrocarbons difficult or impossible to
preferred to use a considerable excess of water
separate from furfural by fractional distillation
over that required to dissolve all of the furfural
either because of their close-boiling nature or by
contained in the oil-furfural mixture; for exam
reason of the formationof azeotropes between
ple, enough water to give a solution of furfural
them and furfural, may be more easily freed of
in water which isi not over 50% saturated rang
these hydrocarbon contaminants by Water ex
ing down to 10% saturated at the extraction tem
traction provided a light hydrocarbon is present
50 perature. Use of .too much Water is undesirable
in the extraction zone.
because it requires an excessive amount of heat
As the light hydrocarbon employed in accord
Áto carry tbut; thedistillation applied to the Water
ance withthe present invention, it is' preferred
furfural mixture to obtain the furfural-water
to use a hydrocarbon having not more than eight
azeotrope as the overhead product.
carbon atoms per molecule and >which is vcapable
The extraction may be conducted at tempera
of existing as a liquid under the conditions of
tures ranging in the extreme from 50 to 300 de
the extraction. 'I‘he hydrocarbon should be lower
grees F. but preferably 90. to 150 degrees F. The
boiling or lighter than furfural and hydrocarbons
advantages of moderate temperatures are set
having not over eight carbon atoms per molecule
forth in detail in the copending application of
meet these requirements. Aliphatic hydrocar
bons are preferred. In general, any aliphatic 60 Weinaug'and Buell referred to above. While it
is possible to carry out the extraction at tempera
hydrocarbon having from three to eight carbon
atoms may be employed. The hydrocarbon may
.tures equal to or above the critical solution Item
isobutane, n-pentane, isopentane, normal hexane,
of the use of an excess of water, so that a dilute
etc., up to octanes and octylenes. The lighter the
hydrocarbon the more satisfactory it is. Thus
pentane is preferred to octane. While propane
aqueous phase with respect to furfural results', is
that the solubility of oil in such a dilute aqueous
phase is very low whereas as the aqueous phase
,may be used in the extraction its use may neces- - ^
becomes saturated with furfural the solubility of
perature for proportions of Water and furfural, it
be a paraffin or an olefin, the paraflìns being
would not normally be completely desirable. It is
preferred because of their inertness and lower
solubility for furfural. While in extreme cases 65 preferred to use such a proportion of water that
all of the furfural can dissolve .therein at moder
a dioleiin such as butadiene might be used, in
ate temperatures of not over 150° F., since much
general, the dioleñns are not preferred because
of expense, excessive solubility for furfural, and
better recovery of furfural from oil' is thereby ob
other considerations. Examples of suitable hy
tained, the loss of furfural in solution in the oil
drocarbons are:A propane, propylene, n-butane,
phase being at a minimum. Another advantage
2,412,823
5
.
oil therein increases.` Another advantage of the
use o1' moderate temperatures, i. e. not over 150°
F., is that the amount of oil dissolved in the aque
ous phase is minimized since the solubility of oil
in aqueous furfural rises with increasing tem
perature.
The pressure at >which the extraction is con
ducted may depend somewhat on the tempera
6
,
tion of oil contaminated furfural with a light
hydrocarbon solvent as disclosed in the copend
ing application of Thodos and Weinaug, Ser. No.
546,371, iìled July 24, 1944. In such case most of
the contaminating oils present in the furfural by ,
reason of their ‘greater solubility in the light
hydrocarbon extractant‘appear in the light hy
drocarbon phase. Some furfural is also dissolved
in
the light hydrocarbon phase. The present in
erately superatmospheric. The extraction is gen 10 vention
is readily applicable to such a light hy
erally conducted in closed pressure-resisting
drocarbon phase to recover the furfural content
equipment in order .to minimize losses by vola
thereof.
‘
tiiization. The pressure is generally suilicient to
The
invention
may
also
be applied to the‘light
maintain all ofÁ the light hydrocarbon employed
extract obtained from extraction of
in the liquid state, that is, either dissolved in the 15 ahydrocarbon
furfural-oil-polymer mixture to free it from
oil phase or as a separate liquid phase.
~
polymer
in accordance with the copending appli
The water extraction may be carried out in
cation of George Thodos. Ser. No. 572,532, filed l
any suitable way, for example, by intimately mix
January 12, 1945. The polymer-free extract re
ing the water, furfural-oii mixture and light
hydrocarbon in a mixing pump or other adequate 20 sulting from such a process 4may be treated in
such manner as to effect separation into a pre
mixing means and then allowing the resulting
dominately light hydrocarbon phase containing
mixture to separate into two phases or layers
most of the oil and some furfural and a purified
in a settling zone or chamber or by continuously
>i'urfural phase relatively free from oil. The light
countercurrently contacting the water extractant
hydrocarbon phase so obtained may be employed
and the furfural-oii mixture in the presence of
.ture but usually ranges from atmospheric to mod
the light hydrocarbon which in such case is usual
ly dissolved in the furfural-oil mixture, in a
column equipped with the usual contacting means
such as bubble caps, packing, etc. The operation
may be either single stage orl multistage and may
be carried out either batchwise or continuously.
The two phases. namely, extract and rañinate, are
separately withdrawn in the usual manner.` The
hydrocarbon phase is fractionally distilled to sep
arate as an overhead the light hydrocarbon from
a bottoms product of the oil contaminants orig
inally present in the furfural. The water-fur
fural phase is also subjected to fractional distil
lation to separate the azeotrope of furfural and
25 as the feed to the present invention.
'
It has been found that vthe presence of a light
hydrocarbon in the water extraction of furfural
from oil greatly Vfacilitates such an extraction.
It brings about sharper separation into a water
furfural-rich phase and a hydrocarbon-rich
phase. The amount of furfural dissolved in the
hydrocarbon phase is considerably reduced and
the amount of hydrocarbon dissolved in the wa
ter-furfural-rich phase is likewise greatly lowered
by reason of the presence of the lighthydrocar
bon in .accordance with `the present invention.
'I'he light hydrocarbon prevents emulsification
between the hydrocarbon phase and the water
water overhead from a bottoms product composed 40 furfural phase, permits shorter settling time and
effective separation between furfural and
essentially of the remainder of the water which i more
oily
contaminants.
is recycled to the water extraction unit in order
The invention will be more readily understood
to save water and the small amount of furfural
by referring to the accompanying drawing which
which may be dissolved therein. The overhead
vapors are cooled and totally condensed and the 45 .shows one possible modification. In `the draw
ing, the feed maybe Iderived from a furfural
condensate caused to form two separate liquid
puriñcation process wherein light hydrocarbon is
layers. The upper layer is composed of water
used for separating the hydrocarbon contami
nants from the furfural. The hydrocarbon-rich
phase, containing a small amount of furfural be
50 fore removal of the light hydrocarbon treating
furfural productsl or jme,lirwlention..y
` " “`
agent, enters via line i and is intimately mixed
The light hydrocarbon obtained by distillation
with
water entering via line 2 and fed into ex
of the hydrocarbon phase is recycled to the ex
traction
settler 3 where two-phase separation
traction unit either directly or by recycling to
occurs. If desired, a mixing pump 4 may be
the unit wherein the furfural‘is extracted with - interposed for‘the purpose of effecting intimate
light hydrocarbon; in the latter case the light
admixture of the water and the feed. In set
hydrocarbon ultimately appears in the feed to
tler 3 a hydrocarbon-rich phase, greatly reduced
the process of the present invention. The process
in furfural content, is obtained >as the top layer
of the present invention is preferably carried out
and a water-furfural-rich phase as the bottom
under such conditions that the hydrocarbon phase 60 layer.
The hydrocarbon-rich phase is fed via
(rafllnate) does not contain more than 3 weight
line 5 to fractionator 6 `where the light hydro
per cent of furfural and that the extract phase
saturated with furfural at the existing temper
ature and is totally reiluxed to the azeotrope co1
umn while the lower layer constitutes the oil-free
` carbon treating agent is recovered as the over
does not contain more than 0.1 weight per cent
of oil. 'I‘he former limitation insures against \ . head product. 4The overhead product is con
excessive loss of furfural and the latter speciñca 65 densed, a portion is refiuxed to column 6 and
the remainder is recycled via lines 'i and 8 to
tion insures that the purified furfural product
the
furfural purification process (not "shownl,
contained not over 0.1 weight per cent of hydro
The bottom productfrom fractionator 6 is with
y
drawn via line 9 and consists primarily of the
'I'he process of the present invention is applica
hydrocarbon contaminant greatly reduced in fur
ble to any oil-furi'ural mixture. The light hydro 70 fural
content.
,
carbon may be already present in the oil-,furfural
Thev
water-furfural
phase
from
settler
3 is
mixture or it may be added in any suitable way
`withdrawn via line i0 and fed to azeotrope col.
in the zone in which the water extraction is con
umn I i wherein there is taken overhead the azeo
ducted. The invention is especially applicable to
carbon.
trope of water and furfural. The overhead is
the oil-furfural mixture obtained by the extrac 75 completely
condensed and allowed to separate
2,419,898
8
’ and is totally reiluxed via line I3.
The lower
layer consists of furfural saturated with water
and is withdrawn via line Il as the product of
the process, The bottoms product from column
I I is composed essentially of water and is recycled
via lines I5 and 2 to the extraction unit. If de
sired, makeup water may be introduced to the
system vla line I6. In situations where the in 10
of the same amount of furfural from 100 pounds
oi’ feed as in the above example was about 11_0
pounds.
.
.
,
present invention- presents numerous advantages
over simple water extraction in the absence of a
ght hydrocarbon as disclosed in the copending
gpplication of Weinaug and Buell referred to
bon or does not contain a sufficient concentration
above. \ The process of the present invention
of a light hydrocarbon, light hydrocarbon is in
troduced'to the water extraction system vial line
l1. If desired, a portion or all of the light hy
drocarbon flowing in line 'I may be recycled di
rectly to the water extraction system by means
»
'
Emmiple
A hydrocarbon-furfural mixture derived by
i
From the foregoing it will be seen that the
coming feed does not contain a light hydrocar
of lines I 8 and I1.
.
each case. The remaining equipment was the
same as inthe above described modification. In
the three-stage countercurrent arrangement the
amount of water required to effect the removal
into two layers in accumulator I2. The upper
layer consists of water saturated with furfurai
brings about a sharper separation between fur
fural and oil and substantially reduces the loss
of iurfural, correspondingly increasing the re
covery of valuable furfural. Thev phase separa
tion is accomplished more easily andwith less
emulsification and >in a shorter time. Other
20
advantages of the process of the present inven
tion will be apparent to those skilled in the art.
I claim:
_
.
treating contaminated furfural with a light hy
1. The process for recovering furfural from
drocarbon, n-pentane, in the manner described
admixture with hydrocarbons having boiling
above to remove the hydrocarbon contaminants
was intimately mixed with water and introduced 25 points so close to that of furfural as to be diillcult
to separate from furfural by distillation which
into extraction settler 3. The composition ofthe
comprises subjecting such furfural-hydrocarbon
hydrocarbon-furfural mixture was:
mixture to water extraction in the presence of a
Furfurai- ____________________ __pounds-6.1
liquid hydrocarbon having a boiling point sub
Water
'
`
do
Heavy oils
‘
Trace
stantially lower than the `boiling point of fur
1.2 30 fural.
`
dn
Normal pentane ______________________ __
92.7
2. The process for recovering furfural from ad
mixtu're with hydrocarbons having boiling points
I
I
100.0
so close to that of' furfural as to be difdcult to
separate from furfural by distillation which com
prises subjecting such furfural-hydrocarbon mix
ture to water extraction yin the presence of a liq
uid hydrocarbon having not more than 8 carbon
Four hundred sixty pounds of water were used
. per 100 pounds ofv feed of the above composition.
In extraction-settler 3 two liquid phases sepa
rated, a hydrocarbon-rich and a water-furfural
rich phase. The hydrocarbon-rich phase con
sisted of about 0.95 pound furfural, trace of wa
ter, 1.2 pounds heavy oils, and 92.7 pounds nor
mal pentane per 100 pounds feed. The water
furfural-rich phase consisted of about 460 pounds
atoms per molecule-
i
3. 'I'he process for recovering furfural from ad
mixture with hydrocarbons having boiling points
so close to that of furfural as to be dii'iicult to
separate from furf'ural by distillation which com
prises subjecting such furfural-hydrocarbon mix
water, a trace of’ heavy hydrocarbon.' and 5.15
pounds furfural. The hydrocarbon-rich phase
ture to water extraction in the presence of a liq
was fed to fractionator 6 to recover substan
uid aliphatic hydrocarbon having from 3 to 8_
tially pure normal pentane as the overhead prod
carbon atoms per molecule.
mixture with hydrocarbons having boiling points
ulator I9. A portion of the overhead product
was returned to fractionator 6 as reflux.
'
4. The process for recovering furfural from ad
uct which was condensed and collected in accum
so close to that of furfural as to be diñicult to
The l
separate from furfural by distillation which com
prises subjecting such furfural-hydrocarbon mix
remaining portion was recycled via lines 'l and 8
to steps (not shown) for removing relatively
heavy hydrocarbon contaminants from furfural.
The bottom phase from extraction-settler I3 was .
ture to water extraction in the presence of a liq
uid paraffin hydrocarbon having from 3 to 8 car
fed to water-furfu'ral fractionator II. In this
bon atoms per molecule.
`
'_
5. The process for recovering furfural from ad
fractionator a furfural-water azeotrope was
mixture with hydrocarbons having boiling points
taken overhead, condensed,'coo1ed. and collected
in accumulator I2. Two liquid phases'separated
so close to that of furfural as to be difficult to
separate from furf‘ural by distillation which com
rich and the lower phase was furfural-rich. The 60 prises subjecting such turfural-hydrocarbon mix
in accumulator I2; the upper phase was water- ‘
ture to water extraction in the presence of liquid
normal pentane.
6. The process for recovering furfural from ad
water-rich phase was totally refluxed to frac
tionator I I. The furfural-rich phase constituted
the purified furfural product which was returned
via line I4 to butadiene recovery steps (not
shown).
-
‘
mixture with hydrocarbons having boiling points
so close to that of furfural as to be diflicult to
n
separate' from furfural by distillation which com
prises-subjecting such furfural-hydrocarbon mix
ture to water extraction ln the presence of a liq
uid hydrocarbon having a boiling point substan
The bottom product from fractionator II con
sisted of substantially pure water. ThisA Water
was recycled to be mixed with the hydrocarbon
furfural mixture before introduction into extrac
tion settler 3.
>
»
70 tially lower than that of furfural, separately
In another modification of my invention a
three stage countercurrent extraction arrange
ment was substituted for extraction settler 3.
Water was introduced at the top and the hydro-l
carbon-furfural-rich mixture at‘the bottom in w
s
withdrawing the resulting aqueous phase and the
resulting hydrocarbon phase, subjecting said
aqueous phase to fractional distillation in a frac
tionation column and thereby separating it into
an overhead fraction of furi'ural and water in
2,412,823
azeotropic proportions and a bottoms fraction of
water, condensing said overhead and causing the
liquid condensate to separate into a water phase
and a furfural phase essentially free of hydrocar
bons, withdrawing said water phase and reflux
ing said column therewith, and separately with
drawing said furfural phase as the product of the
process.
`
’
10
ing hydrocarbon phase, subjecting said aqueous
phase to fractional distillation in a fractionation
column and thereby separating it'into an over
head fraction of furfural and water in azeotropic
proportions and a bottoms fraction of water, con
densing said overhead and causing the liquid con
densate to separate into a water phase and a iur
'
fural phase essentially free of hydrocarbon, with~
drawing said water phase and refluxing said col
mixture with hydrocarbons having boiling points 10 umn therewith, separately withdrawing said fur
7. The process for recovering furfural from ad
so close to that of furfural as to be difficult to
separate from furfural by distillation which com
prises subjecting such furfural-hydrocarbon mix
ture to water extraction in the presence of a liq
uid parañln hydrocarbon having from 3 to 8 car
bon atoms per molecule, separately withdrawing
the resulting aqueous phase and the resulting hy- »
drocarbon phase, subjecting said aqueous phase
fural phase as the product of the process, and
subjecting said hydrocarbon phase to fractional
distillation to separate as an overhead said par
aflin hydrocarbon having from 3 to 8 carbon
15 atoms per molecule from a bottoms fraction of
said hydrocarbons having boiling points close to
that of furfural.
9. The process for recovering `furfural from
to fractional distillation in a fractionation co1
admixture with hydrocarbons having boiling
umn and thereby separating it into an overhead 20 points so close to that of furfural as to be dif
fraction of furfural and water` in azeotropic pro
ilicult to separate from furfural by distillation
portions and a bottoms fraction of water, con
which comprises subjecting such furfuralèhydro
densing said overhead and causing the liquid con~
carbon mixture to water extraction in the pres
densate to separate into a water phase and a fur
ence or liquid normall pentane, the amount of
fural phase essentially free of hydrocarbon, with
said-normal pentane being such as to give a
drawing said water phase and refiuxing said col
umn therewith, separately withdrawing said fur
fural phase as the product of the process, and
subjecting said hydrocarbon phase to vfractional
distillation to separate as an overhead said hy
drocarbon having from 3 to 8 carbon atoms per
molecule from a. bottoms product of said hydro
-carbons having boiling points close to that oi'
furfural.
8. 'I'he process for recovering furfural from ad
mixture with hydrocarbons having boiling points
so close to that of furfural as to be diftlcult to
separate from furfural by distillation which com
prises subjecting such furfural-hydrocarbon mix
ture to water extraction in the presence of a liq
uid paraiiln hydrocarbon having from 3 to 8 car
bon atoms per molecule, the amount of said par
aiììn hydrocarbon being such as to give a weight
~' weight ratio of normal pentane to said hydro
carbons having boiling ponts close to .that of
furfural of from 10 to 1 to 100 to 1, conducting
said water extraction at a temperature o1' from
90 to 150° F.,«separate1y withdrawing the re
sulting aqueous phase and the resulting hydro
carbon phase, subjecting said aqueous phase to
fractional distillation in a fractionation column
and thereby separating it into an overhead frac
' tion of furfural and water in azeotropic propor
tions and a bottoms fraction of water, condens
ing said overhead and causing the liquid con
densate to separate into a water phase and a
furfural phase essentially free of hydrocarbon,
withdrawing said water >phase and refluxing said
column therewith, recycling a bottoms> fraction
of water to said extraction step, subjecting said
hydrocarbon phase to fractional distillation to
ratio of said paramn hydrocarbon to said hydro
separate an overhead of normal pentane from a.
carbons having boiling points close to that of 45 bottoms product of said hydrocarbons having
furfural of from 10 to 1 to 100 to 1, said water
boiling points close to that of furfural; and re-v
extraction beingV conducted at a temperature `
cycling said normal pentane to said water ex
ranging from 90 to 150° F., separately withdraw
traction.
ing the resulting aqueous phase and the result
BERTRAND JESSE MAYLAND.
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