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July 25, 1950 k
v >
Filed July 23] 1945
Patented July 25, 1950
Harry Borden Marshall, Toronto, Ontario, and
Charles Alfred Sankey, St, Gatharines, Ontario,
Canada, assignors to The Ontario Paper Conr
, pany Limited, Thorold, Ontario, Canada .
Application July 23, 1945, Serial No. ‘6063690 3
In Canada July '9, 1945
5 Claims. (Cl. 252-476)
This invention relates to the production c1’
action is stopped when the vanillin content of
the reaction mixtureis at or near its maximum;
vanillin from lignin-containing substances and
especially from the e?luents from acid'chemical
the rate of flow of air or oxygen must be suffi
processes for producing paper pulp, for example,
waste sulphite liquor, and to products derived
therefrom, as well as e?luents from alkaline
chemical processes for producing paper pulp, for
example residual kraft liquor and residual soda
cient to promote good agitation and should pro
vide a quantity of oxygen during the reaction
period of several times that required to supply
16 grains oxygen (one-gram atom oxygen) per
200 grams lignin (approx. one gram molecule of
lignin building unit). The concentration of
alkali is also important. With alkali concentra
It is well known that some vanillin is produced
tions up to‘100 grams sodium hydroxide per litre
when e?iuents from acid chemical processes for
producing paper pulp are subjected to the action
of reaction mixture the vanillin yield increases
of suitable oxidizing agents especially under
with increasing concentration. In applying our
invention a concentration of alkali will prefer
alkaline conditions,
We have now discovered a method by‘ which 16 ably be selected from economic considerations 0
alkali cost versus vanillinyield. ‘
air or oxygen may itself serve as an oxidizing
agent to effect the production or vanillin at
It will be apparent, therefore, that we have
highly satisfactory yields. We areaware that
discovered a method by means of which vanillin
air or oxygen have previously been usedto bring
may be obtained from lignin-containing sub
about the production of vanillin from lignine V20 stances at greatly reduced cost, the only auxiliary
chemicalsrequired being alkali and air.
containing substances under alkaline conditions
but, in general the yields obtained have been
It is well known that certain speci?c oxidizing
unsatisfactory, indeed it has even been reported
agents have been used to obtain vanillin from
lignin-containing substances. For example, the
that the yield of vanillin is decreased by ‘the in
troduction of air into the reaction mixture dur-v 25 use of copper sulphate is well known. We have
ing the course of vanillin production "therefrom.
discovered that by using air or oxygen in ac
cordance with our invention and in addition
The essence of our present invention lies in
the fact that air or oxygen may be employed to
having present a quantity of such speci?c oxidiz
,ygreat advantage if it is ?nely dispersed so as to
ing agents the yield of vanillin may beiiurther
provide adequate contact with the alkaline 30 increased even-when relatively'small quantities
lignin-containing liquor under conditions of
of such oxidizing agents are presentn
Our invention thus permits the use of ‘greatly
pressure and temperature which are controlled
so as to bring the reaction mixture to a sum
eiently high temperature so that the reaction
’ rate is thereby increased and at the same time 35
reduced quantities of such other oxidizing agents
and hence effects substantial economies in their
‘so that the conditions of oxidation .are not
rendered su?iciently severe to result in the de
We have also discovered that a catalyst may
be used to increase the yield of vanillin when
composition of a substantial portion of such
our invention is employed '
To prepare a catalyst such as we prefer to em
vanillin as is. formed.- We ‘have found that re
action pressures in. the range 59-200 lb- Per 40 ploy, copper sulphate may be added to waste
sulphite liquor or to the-liquor remaining, after
square inch and attemperatures inthe range
. ism-200° C... atsueh pressures give highly satis
‘ waste sulphite liquor has been passed through a
- rectory yields of vanillin.- {Since in accordance
plant to produce ethyl alcohol, which latter is
' with our invention. the yield of vanillin is also
herein referred to as “alcohol plant ef?uent” and
dependent on conditions other than the tem- ' > subjected to an alkaline oxidation with ?nely
perature and pressure in thereaotion vessel, the
divided air or ‘oxygen under pressure in accord
reaction conditions to obtain optimum yields
ance with our present invention, At the con
must be selected with ‘additional-‘factors in mind.
, The time or reaction should be selected having
regard to the otherconditioos so that: the rec
‘7 clusion of such oxidation there will be present in
the reaction mixture'a sludge containing sub-,
stantially all the copper which: was .‘ added as
2,51 6,827
copper sulphate. This sludge seems to be com
posed of a mixture of various copper oxides and
duction of vanillin from the e?iuents from acid
chemical processes for producing paper pulp as
hereinbefore described but also to the production
of vanillin from the e?luents from alkaline chem
possibly metallic copper but its exact composition
is not known to us.
The said sludge may be
removed from the reaction mixture by ?ltration 5 ical processes for producing paper pulp, such as
or centrifuging or any other suitable mechanical
residual kraft liquor and residual soda liquor.
means. This sludge without any further chem
Hitherto the treatment of such alkaline process
ical treatment is a catalyst which, when added
ef?uents by oxidation procedures for the pro
to subsequent reaction mixtures in which air or
duction of vanillin has been unsuccessful, only
oxygen is used as a primary oxidizing agent in 10 minute quantities of vanillin, if any, being formed.
accordance 'withjour invention; will serve to in
iThelexamples hereinafter suppliedzwill show that
crease thewyield'or-vanillin therein to a higher
value than if such catalyst were not present.
The sludge recovered from a subsequent reaction‘
by-your' method commerciallysatisfactory yields
?ve times without diminution ‘of its effect over
the materials and conditions described in these
of vanillin may be obtained from such effluents
even when no additional alkali is employed.
may be reused in a succeeding reaction and so 15 H The following description of experiments which
on from reaction to reaction. ' Its e?iciency in‘
have been performed by us will serve to illustrate
such a series of reactions appears to be main
‘the application of our invention. It is to be
tained. We have reused such a catalyst at least
' understood that our invention is not limited to
and above that of a reasonable experimental 20 experiments which are to be considered as ex
error in determining the vanillin formedin each-1 ~ vamples only. . vIn the majority of the experiments
ease. Such continued reuse is of course‘ con; a; thelignin-containing substance used was alcohol
tingent on minimizing mechanical loss of, M plant effluent. This is a preferred substance to
catalyst in the cycle.
which our invention may be applied.
The ?gure shows in diagrammatic form an ap- 25 ,
paratus which‘we have used in some of our experi
ments and comprises a bomb" I, into which the
v‘E._'rr'z'1'1tple >‘1_.'_'—\-'Illustrates the use "of air1 as oaiz'dz'zz'ng
reactants are introduced; a cover 2, containing
an opening 3, leading to a condensing vsystem 4, y‘
, 'On'ej litre of alcohol'plant effluent was heated
in which vapours‘ from the bomb ‘may be con- ‘30 with 100 grams of caustic soda in the previously
densed and returned'thereto by re?ux through
‘described; ‘apparatus, ‘Throughout the heating
the opening 3, the condensersystem terminating
cycle ‘asteady flow of ‘compressed air,‘su?icient to
in the control relief valve15, ‘which limits the
insure good agitati‘omwas ‘di?used through the
maximum pressure in the reaction‘ system to a
liquidythe valve ,5 being adjusted to relievegas
predetermined value. In the bottom of the bomb 4} £15 at 110 lb‘. persquare. inch pressure. No, catalyst
I, is a porous plate 6, beneath‘which air or‘ oxygen
'orspecial oxidizing agent such ascopper sulphate
may be introduced and which’se'rves as a gas dif
The ‘apparatus was‘heated suf?
fusing means by which‘ air or oxygen enters the
ciently so ‘that the reactantsweresubjected to
reaction zone in a ?nely'dispersed'state' The, ,
air or oxygen is supplie
d from‘ a pressurecylin- "
der 1, through waive“, ‘9, which control‘ the
pressure and rate of discharge from the ‘cylinder
into the gas diffusing means by'tube l0; '
-‘ " "
an observed temperature of IBQ-I'ZQ" 'C." The ap
paratus ‘was maintained under ‘these conditions
in three hours. _ ‘At thepconclusion of this treat
‘ment', the air (?ow was turned' off, the system, was
cooled to japlower temperature “thanpits boiling
The" bomb‘ is falso’equipped with a ‘pressure,
pointgatatmospheric pressurajand the. pressure
gauge" I l, and a thermometer well 12, containing 215 reduced ,to' thatof the'_,atmosphere by'the relief
a thermometer 13,} by‘ means of ‘which ‘the pres
valve‘, l5; Theresiduall liquor. was‘ then analysed
sure and temperature of 'the' reaction may be
vanillin content and?thellatter"correlated
noted. The bomb I, may be heated by any 'con
with the‘ .orginal lignin content ithereof . A ' yield
venient means, for example, a gas ‘flame I41 ‘A_
of vanillin of 111.5 %‘,_based on the said _lignin_con—
relief valve 15,‘ is provided for general pressure 50 tent was obtained,‘
' ‘
' '
In all experiments‘ cited in ‘this speci?cation
the lignin content of lig'ninicontaining substances
Examplé‘lzf-élllustrdting the use bf‘small queui
‘ ‘ tity' ‘of copper sulphate hydrate inconiiunction
was estimated in terms of the methoxy] contentv _
a’z'r cndinlsor‘illustrating preparation of
thereof." The chemicalgroup v01-130, or methox'yl" as
group, is well knownt‘o be a'fchara‘cteristic‘ com
ponent part’ of ' lignin'and'is chemically'l deter
a" [3 one‘ litre of' alcohol plant effluent‘ was : heate
minable with reasonable‘ "accuracy ‘vby'well-kn'own
analytical procedures. ""It isvalid' to assume that
‘with 100 grains of caustic‘soda and 16‘gra'mscoP
' per ‘sulphate hydrate in‘ the‘ previously described
the lignin of a complex mixture containing li'gnin so apparatus. As'in‘Exa‘mple' 1, air was-dispersed
is proportional to the-methoxyl' content thereof. “through the‘ reaction‘ zone,‘ with thevalive' 5 ad
‘ juste'd‘ to‘ relieve fgas'fat" 110" IbL‘Yper ‘square inch
' In our experiménts'it‘ is‘assumed that the ratio
of methoxyl content‘to‘ lignin' content of any‘ of
" pressuratheireaeuen time at' an obsei‘Ve‘dFtBm
the mixtures investigated is‘<l5'.5’ to 1100.‘ Such an
perature‘iio'fil?ilt'l'l?mC. being three hours; ‘The
' assumed ratio is in accordance‘ with currentgoiod
chemical usage in dealing with lignin-containing
65 experiment'was concluded with temperature and
substances. Whether this ‘assumed ratio is or is
not numerically correct is immaterial because the
ratio ‘of methoxyl"to lignin maybe reasonably
‘i pressure‘ adjustments as ' in ‘Example :1? and‘v the
' reaction mixture ‘removed ‘from, the bomb, ‘care
being taken to thoroughly wash‘? out a' sludge
“formed. therein; This sludge,‘ as 'her'einbe'fore
assumed to be constant‘forany given ligninlfc'on 7o stated-,"is a‘ catalyst in accordance with our inven
taining ‘substance. The‘ assumption of'the above
tion and was" removed from? the‘ reaction mixture
ratio will, therefore, serveiforpur'poses of ‘obtain
mg a valid relative guide‘ to the‘quantity of 'lignin
in ligninécontaining‘substances. '
Our‘inventioneis‘fapplicable not only tdthelpro:
' ' In this experini n'ti'a‘ ‘yield of vanillin‘fwas'ob
'tain‘e" ‘equivalent to 14.4% oft-he‘ original lignin
1s content‘dilthealcoholgplant‘e?luentfii
25am? with ‘constant air-now! "The pressure- was
adjusted to give a series- of increasing pressures,
the corresponding temperatures being-1 noted? inv
‘ One litre of ‘alcohol 'plantei?uent. was - heated
each case. The reaction mixturelwa‘si maintained
witlrlOO grams of. caustic soda andthe catalyst
for three‘ hours under ‘the stated conditions.
vanillinv yields were obtained‘ as'f'oll'owsz'
recovered from'Example 2; rrl'llhe experiment was
conducted in a similar manner to Example lathe
pressure being adjusted tje~110 lb. pensqnare inch
and the time at 16994709‘- Gpbeingithree hours.
At the conclusion "or the experiment-thecatalyst
was recovered from the» reaction ‘mixture: as‘ in 10
Example 2. In thisexperiment a; yield of vanillin
was obtained equivalent to 12.7% of .tlre-éoriginal
Relief Pres- "Temperature ,Vanillin
, >_ .
~ The catalystrecoveredfromthe. above was re- :15
used in a series of experiments in-whichthe con
. Yield.
-. q -
Per cent
lign-in - content of - the alcohol plant. ef?uenn; .1: h 1
183 .
' l3. 5
ditions of“ Example 3 were repeated. In this
series vanillin yieldsfof _f1‘4.s %r. 15.6%, 14.2%, and
13.8 % vanillin raiibe‘sedtnitnei lignin content)
were obtained on the second, third, fourth, and
?fth successive reuse oftheeatalyst, no additional
copper sulphate being added‘ in any experiment
Example 4.—Illustrati1tg the use
In another similar‘series of a different alcohol
plant eilluent the maximumyield for a: two-hour
reaction time" was with the pressure of 1'70 lb.
per sq.’ in. and at an observed temperature of
182° 'C-i‘ ‘at which-‘a £3.5‘7i'yield; or vanillin .was
‘ obtained’.
as an ’
n ‘One; litre of alcohol plant de?luent waslhea'ted
with IOO'grams of caustid‘soda‘ and ld'gram's of
copper sulphate hydrate‘ in the previously de
scribed apparatus. Oxygen was dispersed through
V . 0
‘the'rea'ction zone with the valve 5 adjusted to
‘relieve iga'sat '70 lb. ‘pen's‘clilar'ejinch; 'l‘riressure.
‘Employing. conditions similar to ‘example-.2
witlr a 3 hr. reaction time: and pressure at 119-115
lb.-/sq..»in. and using 109 grams caustic; soda. three
experiments were performed in whichthe rates
oiair- flow were respectively. 3.3, 6.9,. and. 13.4 cu,
ft.»>per.hour. The vanillin yields obtainedwere
‘The observed temperature‘ ‘was 151° C.’ I The re
9.6%,, 1&5 %, and, 14.75. %-. respectively.
action time under the above conditions was 1%
hours. _A yield of vanillin of 12.2%‘ of the lignin - _
content or the‘ 'et‘ov'e'plant em, ‘t was" obtained. 35
Example 5.-Illustmting ‘thee-use of vunzsfte sulphite
_;'-'="liquor .;
; -
‘ Employing conditions zsimilarv a‘,
ay 3- hr. reaction time and-pressure at 110415
- ‘ One ‘litre orwasre sulphite' li'quo'r- wesjtreated
1‘ ‘4:0’
as in Example 2.
A yield of vanillin was obtained equivalent to
10.8% of the lignin content thereof.
Example 6.—Illu'strating the use of soda liquor
One litre of a liquor resulting from the pro 45
duction of pulp by the soda process was heated
with 12 grams copper sulphate hydrate in the
previously described apparatus, no additional
alkali being added. The pressure and reaction
time and temperature were as in Example 2.
Ila/seq. in- and-with constant. air ?ow, the vanillin
yield changedv as- follows with alkali concentra
Alkali concen.
Grams per liter
Per cent
0. 8
5. 9
10. 7
14. 5
12. 2
A yield of vanillin was obtained equivalent to
3.8% of the lignin content thereof.
In the examples cited above it must be noted
Example 7.—-Illustmting the use of kraft liquor
that the conditions of agitation are dependent
One litre of a liquor resulting from the pro 55 on the details of the reaction vessel. It must
not be expected therefore that using di?erent
duction of pulp by the kraft process was treated
as in Example 6.
A yield of vanillin was obtained equivalent to
3.2% of the lignin content thereof.
Example 8.—Illustrating the use of wood meal
reaction vessels and di?erent lignin-containing -
substances that the above results will hold for
all cases. For example, it would be incorrect to
assume that a pressure range 110-115 lb. would
necessarily always give a maximum vanillin yield
for a 3 hr. reaction period. The examples are
60 grams spruce wood meal were added to one
illustrative of the yields we have obtained by em
litre of a solution containing 100 grams caustic‘
ploying our invention and provide a guide as to
soda and sixteen grams copper sulphate hydrate
the effect of variables which will enable others
and subjected to the oxidation procedure simi 65 to apply our invention to maximum advantage
larly to Example 2. A vanillin yield correspond
ing to 13.7% of the lignin content of the wood
in their own case.
meal was obtained.
is used it is to be understood that we refer to
gauge pressure and not absolute pressure.
Example 9.—-Illustrating the combined effect of
pressure-temperature and reaction time on 70
vanillin yield
A series of experiments were carried out with
When in this speci?cation the word “pressure”
The words “lignin-containing substances”
when used herein, have reference to the species
of chemical individuals which are present in
ligno-cellulose materials and to which the word
lignin is applied including derivatives of the
a single sample of alcohol Plant e?iuent, with
alkali and copper sulphate hydrate as in Example 75 same which result from chemical processes for
producing wood pulp and; arepresent inkthei‘rei
sidua-l liquors from said processes.
._ , a ,
‘=- The chemical identity and nature. ofligninas
originally present in .ligno-cellulose materials
and in the species lignin-containing substances,
has not been established. The scopeof the term
lignin as herein used, may be de?ned as by
Brauns in “Cellulose and its Derivatives,” edited.
stances in an alkaline""medium,and subjecting
such combinedmaterials-to the action of a ?nely
dispersed gas containing tree gaseous oxygen, re
‘covering-the ‘sludge fromsaid process and re
peatedly reusing said sludge as a catalyst in the
productio'nvof‘ vanillin according to the said
'4.-A1method of producing vanillin according
to claim; 3 in'which the'lignin-containing sub
by Ott, Interscience Publishers Inc., ‘?rst edition
1943, page 449, line 7 ff.
it stance‘ consists of‘ waste sulphite liquor.
' 5.‘ A method of producing vanillin according to
What we claim as our invention is:
1. A catalyst which assists in the production
of vanillin consisting of the sludge residual in a
reaction mixture in which vanillin has been
claim‘ 3 inywhich the-lignin-containing substance
is'thee?luent from a process vin which waste
sulphit'ev liquor-has been so treated that as a re
produced by subjecting, to the action of a ?nely ll! sult the'i‘fermentable sugar ‘content thereof has
dispersed gas containing free gaseous oxygen, ‘ '
been substantially‘ reduced.
lignin-containing' substances in an alkaline me
diumvto which‘ has been added copper sulphate
under conditions of temperature in excess of 140°
C; and partial pressure of ‘oxygen ofless than 20 ‘go
lb. per sq. in.‘
2. A method of producing vanillin which con—
sists in subjecting to the action of a ?nely dis
persed gas containing free gaseous oxygen a re—
' The following references are of record in the
?le of this patent:
action mixture comprising lignin-containing sub- 35
stances in an alkaline medium to which has been ' ’
added copper sulphate, separating the residual
‘sludge therefrom,‘ adding said sludge to -a re
action mixture containing lignin-containing' sub~
2 2,434,626 _
_ Salvesen .>..'.__'______ __ Jan. 13, ‘1948
stances in' an alkaline"medium and subjecting 30
‘such combined materials to the‘action' of a ?nely
‘dispersed gas containing free gaseous oxygen.“
3. A method of producing vanillin which con
sists in subjecting to the action of a ?nely dis
persed gas containing free aqueous oxygen a re- ,35 '
action mixture comprising lignin-containing sub
stances in an alkaline medium to which has been
added copper sulphate, separating the residual
537,845 r
“ ‘ a; "
Germany ______ __ Dec. 14, 1931
Germany-,- _____ __‘ Dec. 14, 1931
ser. No.‘318,386',‘Freudenberg et al. (A. no),
pub. April 20, 1943.
Lautsch et. al., “Angewandte Chemie,” vol. 53,
pages 450-452, September 28, 1940.
sludge therefrom, adding said sludge to a re1 Pearl f‘Jour. Am.:chem. $00.," vol, 64, pages
action mixture containing lignin-cont'ainingsu - 440 ‘14294431.
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