Note: Descriptions are shown in the official language in which they were submitted.
~17~1l33
oRIFICL~ Pl,AT~ MIX~R AND METIIOD OF_USE
~rhe inventiorl relates to an orifice plate mixer and
methods of using it.
This application is a division of our copending
Cauadian applica-tion Serial no. 252,555 filed May 14, 1976.
There are many mixing operations in which two or more
fluids are to be mixed as quickly as possible to avoid local
high concentrations of one of the fluids in contact with the
other fluid. Examples of such operations are sulphonation,
sulphation or halogenation reactions in which the organic
reactant is sensitive -to high concentrations o~ the sulphona-
ting/sulphating/haloyenating reagent. Among known mixers are
orifice plate mixers, which are described for use in such reac-
tions in e.g. British Patent Specification No. 975,914. In
this patent specification the sulphonating/sulphating reagent,
which l S a sulphur trioxide/air mixture, is caused to flow in
an axially directed pipe passing through the axial orifice of
the orifice plate mixer with emission of the reagent into the
turbulent area downstream of the mixer.
We have now found -that an improved mixing action can
be obtained if one of~the fluids is introduced through a port
located in the internal wall of the axial orifice of the plate.
Our invention provides a turbulent flow plate mixer
for mixing at least two fluids which comprises an orifice
which is substantially perpendicular to the plate and a port
in the internal wall of the orifice, the orifice being for
passage of the first fluid and the port being for passage of
the second fluid. The orifice constitutes a bore through the
plate with the port a passage in the wall of the bore.
This configuration gives a hiyh degree of turbulence
an~ mixing because the fluid passing through an orifice in the
plate experiences a relatively high pressure drop and has
`- a high Reynolds
- 2 -
33
Number at the poin-t of mixing the two fluids; this is true
even if the diameter of the oriEice is relatively large;
the length of the orifice is relatively small, being
only the thickness of the plate, thus allowing substantial
vortex formation and turbulence downstream of the orifice
as well as in the orifice.
These characteristics distinguish the turbulent
flow plate mixer of the invention from Venturi tubes
in which the pressure drop is minimized by providing
a convergent entry to and divergent exit from the tube,
both of small angle; the velocity is maximized and the
turbulence minimized by providing a comparatively small
diameter of bore; and the length of the tube ls comparatively
large.
The duct leading the second fluid to the port
in the wall of the orifice may be drilled through the
thickenss of the plate, conveniently in a radial direction.
It is not, however, essential that the port be flush
with the internal wall, and it is possible to introduce
; 20 a pipe or collar projecting beyond the wall in a radial,
upstream or downstream direction.
The plate may be of circular, square or rectangular
cross section with the orifice preferably at its centre,
the centre of the port is preferably about equally spaced
from the ends of the orifice, e.g. at a distance of 40 -
60% of the length of the orifice from the end of the
orifice.
Preferably, the mixer comprises an integral
plate in which an axial bore or orifice and at least
one radial duct or port have been fabricated, e.g. by
drilling, the oxifice having the port or ports in its
internal wall.
As mentioned above, the configuration of the
mixer according
'J~L~3
to th~ lnYerltlon can give a high R~ynold3 number to a fluid pag~ing
through the ori1ce. The dimensiona should he such, i~ rela~ion to the
ma~ den~ity of the first ~luid, it~ c~sity ~nd line~r velocity in
the orifice? that the Reynold~ numb~r in the oriflce i8 greater than
the minimum for turbuLent flow, l,e~ 2000~ but prefersbly greater than
30~0~ e.g~ 3000 - 18~0oo~ pre~rably 4l500 ~ 15tO00 a~d especially 10~000
15,000 wh¢n the first fluid i~ a liquld and the ~econd fluid i8 ~oluble
there~ or reacts therewi~h, The greal:er the di~meter of the ori~ice
for a constant voiume of fluid through the ori~ice the ~malle~ ~he
Reynolds number aQd the pres~ure drop across the plate~ 80
.
th~t the choice of diam~ter is a compromise between the deqir¢ for a
'', i -
hi~h Rey~old~ number giving m~ximum turbulenca ~nd avoldance of a high
pro~u~e drop requirlng maximum power i~put. In general the dealgn will
b~ a comprdmis~ o~ the conflicting requ~rement~ o~ high throughpu~ and
- ~ ~15 Reynold~ number with a reasonable applied pump pre~ure on the one hand
and à h~gh pre-~surs dsop across the plate on the other,
Tha d~ameter of the oriiic~ in relation to the thichness of
tho~plae~ l,e.~the leng h~o tho ~ fico ~9~ elstiYoiy hi~h~
.~ of ;at leas~ O.S ~ I~ e~g.~ 1 to 50~ s 1~ preferably 1 ~ 1 to 20: 1~
; 2~ pecislly l,5 s 1 to~l0 : I. lè :will bo~ undorstood that reference~ to
a plato' hcroln include a~fab~icated construc~ion made up of two thin
`. plate9 ~oio-d eogeth2r~ the ~space betw~en them being ouch ao to
sccommcdate a foed pipe to the~port. The i'oriflce" then tAkas the fonm
of a short length of pipe between the two thi~ pla~es.
: 25 I~ de~ired there may Oe:~more ~ban on~ port e.g. 2 - 4 ports
in the internal ~all ~f the orifice. The~e ~a~ be used to introduce
the same or different fluids.
Preferably the firqt fluid i~ ~n organic f2edstock whlch ~s
to be reac~ed wlth the second ~luid in a manner to miuimlse ~Yer-
reaction. Thus the secQnd fluid can be a sulphonating, sulphating or
halogenating reagent where o~er-reaction can produce discolouration of
the product or production of a product having more than
the desired n~ber of substitutent groups. This over-
reaction can also occur in the reaction of h~droxylic
organic feedstocks with an alkylene oxide, e.g. ethylene
oxide where it is desired to add only certain number
of alkylene oxide units to the feedstock and hence minimize
the spread of the number of alkylene oxide units in the
product. While the fluids can be liquid or gaseous,
the first fluid is preferably liquid, while the second
fluid may be liquid or gaseous. The fluids are usually
mutually miscible either because o mutual solution or
reaction.
The present invention also provides a method
of mixing at least two fluids which comprises passing
a first fluid through an orifice which is in a plate
and substantially perpendicular to the plate, and passing
a second fluid into the first fluid through a port in
an internal wall of the orifice.
The method of mixing of the invention will
be described hereafter with reference to the sulphonating/
sulphating of organic feed stocks with sulphur trioxide
in a recycle loop system, but it is equalLy applicable ~
to other reactions in which over-reaction is undesirable
whether or not a recycle loop system is adopted, e.g.
in an in line system with mixing of reactants in the
mixer and subsequent collection of the reaction products.
In the preferred process the mixing plate
used in the present invention forms part of a recycle
loop comprising the plate, a pump, a heat exchanger,
a line joining these together in a loop, and entry lines
into the loop for the feedstock and the sulphur trioxide,
- 5 -
L7~3
.
and a take off line Eor -the product. The entry line
for the ~eedstock is be~ore the mixer plate in the dlrection
of flow in the loop and the entry line for the sulphur
trioxide is i~to the mixer. ~hus the second fluid is
the sulphur trioxide as gas or liquid and the first fluid
is a mixture of organic ~eedstock and its sulph(on)ated
product. Preferably the fluids are mixed into the mixer
before they reach the pump, i.e. the mixer is on ths
inlet side of the pump, and preferably the 1uids pass
through the mixer, pump and heat exchanger before the
take off line is reached.
When a sulph(on)atable organic compound, e.g.
an aromatic compound such as benzene or a fatty alcohol
such as lauryl alcohol is sulph(on)ated by sulphur trioxide,
there is a considerable evolution of heat, which, if
associated with local high concentrations of sulphur
trioxide in the reaction mixture, may give rise to a
heavily discoloured reaction product.
In this specification the terms "sulph~on)ated",
~0 "sulph(on)atable" and "sulph(on)ation" means sulphonated,
sulphonatable and sulphonation, or sulphated, sulphatable
and sulphation, depending on the nature of the compound
reacted; thus aromatic hydrocarbons are sulphonated,
but fatty alcohols are sulphated. In order to produce
light coloured sulph(on)ated products, such as aromatic
sulphonic acid reaction products for use, e.g. as surface
active~agents or hydrotropes or fatty alcohol sulphate
reaction products for use, e.g. as surface active agents,
it is usual to moderate the effects of the heat of reaction
by diluting the sulphur trioxide, either with an inert
gas, e.g. to a 5~ concentration in dry air, or with an
-- 6 --
L3;~
~nert :L~quid diluent, e.~. a chlorina-ted hydrocarbon
or liquid sulphur dioxide. The need for the gaseous
or liquid diluent introduces problems o~ purification
of the diluent before the reaction and removal thereafter
and problems in use. Thus gaseous diluents have to be
dried before use and separated from the reaction product
afterthe reaction without entra:Lnment of product, unreacted
sulph(on)atable compound and/or li.quld diluent. The
presence of gaseous diluents in the liquid reaction mediurn
means that they are more difficult to pump than liquid
phases only. Liquid diluents have to be separated from
the reaction product. It has also been proposed to use
the sulphur trioxide gas as such and undiluted but under
externally applied reduced pressure. It is known to
react the sulph(on)atable compound with liquid sulphur
trioxide in a complicated apparatus in which the sulphur
trioxide is directed at an organic compound present on
the surface of at least four moving impeller bIades-which
are close to heat transfer surfaces. The reacting mixture
of organic compound and sulphur trio~ide is sheared between
the impeller blade and the heat transfer surface to reduce
the temperature. Finally, it is known to sulph(on)ate
sulph(on)atable compounds with a sulphur trioxide/air
mixture in a loop reactor with removal of one fifth to
one thirtieth of the reaction product and recycle of
the rest. It is suggested in a further document that
undiluted gaseous sulphur trioxide could be used in a
continuous loop process but no details are given.
The mixer of the invention can be used to
prepare a sulph(on)ated product by a process with undiluted
liquid or gaseous sulphur trioxide in a simple apparatus
-- 7 --
~7~3
with a loop in which the organic feedstock is diLuted
with its recycled sulph(on~ated reaction product, contact
between organic feedstock and sulphur trioxide occurs
under conditions of turbulent flow in the mixer and the
amount of recycle is very high. The process has the
advantage of requiring no diluent for the sulphur trioxide
and in the case of alkyl benzene feedstocks often gives
light coloured products.
The present invention particularly provides
a process for sulph(on)ating a sulph(on)atable organic
feedstock, which is preferably an aromatic compound or
a fatty alcohol of 8-18 carbon atoms, which comprises
passing a reactant liquid comprising the organic feedstock
and its sulph(on)ation derivative as the first fluid
through a first orifice of a plate, the orifice being
substantially perpendicular to the plate, and having
a port in the internal wall of the orifice, and passing
undiluted sulphur trioxide as second fluid in liquid
or gaseous form through said port, preferably the apparent
Reynolds number of the reactant liquid in the orifice
at the point of meetlng the port being in the range 2000-
20,000, e.g. to 18,000, the liquid being in a condition~
of turbulent flow at the point of contact of sulphur
trioxide and liquid thereafter in the zone of reaction
of sulphur trioxide and liquid, the mixing of the sulphur
trioxide and feedstock producing a reactio;n mixture,
cooling the reaction mixture before and/or after removing
a portion of the reac*ion mixture as sulph~on)ated product,
the weight ratio of reaction mixture removed to the remainder
of reaction mixture being in the range 1:40 to 1:2000,
adding further organic feedstock to the remainder of
-- 8 --
~i~'7~3
the reactlon mixtur~ to compensate ~or that removed as
product and -to reconstitute the reactant liquid and recy~
cling it or contact with more sulphur trioxide.
The compounds which may be sulphonated in
the process of the invention, include aromatic compounds
of 6-36 carbon atoms free from groups unstable under
the reaction conditions, e.g. free amino groups. Examples
are benzene and alkyl benzenes having 1~3 alkyl groups~
each of l-15 carbon atoms, such as alkyl benzenes with
1-3 alkyl groups, each of l to 5, especially l to 3 carbon
atoms, e.g. toluene and the three isomers of xylene,
and monoalkyl benzenes in which the alkyl group contains
8-15 carbon atoms, e.g. dodecyl benzenes, such as benzene
with a linear dodecyl or propylene tetramer side chain.
The aromatic compound may have one or two substitutent
which are halogen atoms, such as chlorine or bromine
(as in chloro toluenes), hydroxyl groups (as in phenol)
or carboxylic groups (as in benzoic acid); the aromatic
compound may have one nitro or one sulphonic acid substituent.
The total number of substituents in any benzene ring
is usually not more than 3. The naphthalene equivalents
of the above compounds, e.g. naphthalene itself may also
be sulphonated. Other classes of sulphonatable organic
feedstocks are olefins, e.g. those of 8-20 carbon atoms,
such as dodec-l-ene, hexadec-l-ene and octadec-l-ene,
or random unsaturated hexadecene or vinylidene olefins,
and fatty acids, e.g. those of 8-20 carbon atoms such
as lauric and stearic acids, as well as olefinic acids,
e.g. of 3-20 carbon atoms, preferably 4-18 carbon atoms
such as maleic, fumaric and oleic acids.
Examples of sulphatable organic feedstocks
.~
3 ;3
are alcohols, pre~erably fatty ones o~ 8-20 carbon a~oms,
such as lauryl, cetyl and stearyl alcohols and mixtures
thereof, including mixtures such as are commercially
available with a larger proportion of one of these
alcohols and smaller amounts of other alcohols. The
reaction products of these fatty alcohols with ethylene
oxide or propylene oxide which usually contain 1-10
of structural units derived from the oxide may be
sulphated. Alkyl phenols with, e.g. 1-12 carbon atoms
in the alkyl group, and the reaction products of 1 mole
o~ them with, e.g. 1-lO moles of ethylene oxide or
propylene oxide, fatty acid alkanol amides, e.g. with
8-18 carbon atoms in the fatty acid part, e.g. that derived
from lauric acid and 2-12 carbon atoms in the alkanolamide
part, e.g. that derived from mono or di or tri ethanolamine,
and the reaction products of l mole of the fatty acid
alkanolamides with e.g. 1-10 moles of ethylene oxide
or propylene oxide may also be sulphated.
Preferably however, the sulph(on)atable compound
is benzene or an alkyl benzene as defined above or a
fatty alcohol. The sulphur trioxide is preferably in
gaseous form.
The sulph(on)ated products may be used in
detergent compositions.
The sulphur trioxide and organic feedstock are
contacted in the mixer when the liquid containing the
feedstock is in a condition of turbulent flow, preferably
with an apparent Reynolds Number of at least 2,000, e.g.
at least 3000, usually 3000 - 18~000, preferably
4500 - 15,000 and especially lO,000 to 15,000. The
-- 10 --
Reynolds Number can be greater than 18,000 but the
higher values become progressively uneconomic. The
apparent Reynolds Number is calculated on the assumption
that there is no gas phase present, i.e. in the case of
the use of gaseous S03 its volume is neglected.
The tubulent flow is achieved by use of the
mixer and also in the loop circuit through which the
liquid flows there is a pump; the requirement for
tubulent flow necessitates a pump operating at a high
pumping rate. The turbulent flow occurs in the mixer
and in the reaction zone wherever unreacted sulphur
trioxide contacts feedstock (or suLph(on)ated derivatives
thereof) and reacts with it. Most pumps and heat
exchangers ~or cooling the reaction mixture keep turbulent
a liquid fed thereinto in a state of turbulent flow.
Fixed pressure pumps, e.g. centrifugal,pumps are preferred
though any other type of pump capable of a high pumping
rate may be used.
Light colour sulphonates from alkyl benzenes
can best be produced if the liquid mixes with the sulphur
~rioxide before passing through the pump rather than
afterwards, i.e. the mixer is at the inlet side of the~
pump rather than the outlet side. The recycle loop
;~ system also contains a heat exchanger as cooler, and
inlet for ~eedstocks and outlet for reaction mixture.
Preferably the cooler is between the mixer and outlet
in the direction of liquid flow. Thus preferably the
sulph(on)ation occurs in a recycle loop reactor through
which is pumped the reaction liquid and mixture, the
reactor having in the direction of flow of the reaction
'
.:
1'7~3
mixture and liquid, an inlet ~or ~eedstock, the mixer
giving turbulent flow into which sulphur trioxide,
preferably in gaseous form is passed, a pump, a heat
exchanger as cooler and an outlet for reaction mixture.
The reaction liquid and mixture are preferably in a
sta-te of turbulent flow in the mixer, pump and heat
exchanger and may be throughout the loop. The sulphur
trioxide and feedstock are passed into the loop continuously
and the sulph(on)ation product i5 removed continuously.
The temperature of the liquid as it enters the
mixer before reaction with sulphur trioxide is primarily
governed by the need to control the viscosity of the
li~uid, the lower limit being that to maintain a viscosity
such that there is turbulent flow, the upper limit being
preferably 150C, and pressure being placed on the
system if necessary to stop volatili~ation of the organic
compound at the liquid temperature. Preferably the
temperature of the liquid is 0 - 80~C, and especially
20 - 60C. The use of high temperatures may tend to
~ive greater discolouration in the sulphonated products
than occurs at lower temperatures, but the viscosity of
the reaction liquid is lower at high temperatures,
~aking for higher turbulence for the sama power input
to the pump or the same turbulence with a lower power
input. A balance is drawn between the opposing factors.
During the reaction, heat is évolved and the maximum
temperature of the effluent reaction mixture is
preferably 150C; the usual temperature is 25 - 65 C.
Generally, there is no externally applied vacuum on
the loop system in which the reaction mixture and
reaction liquid are kept. The loop system is usually
- 12 -
,4 11 ~ ~1
~.li.~ ' L-.J~
maintained with an external pressure of at least
substantially atmospheric, e.g. up to 10 atmospheres
and preferably about atmospheric pressure, i.e. there
is preferably no externally applied pressure or ~acuum.
The liquid which is reacted with the sulphur
trioxide may contain an inert liquid diluent, such as
a chlorinated aliphatic hydro-carbon, e.g. carbon
tetrachloride. Such a diluent may be desirable when
the reaction product is so high melting or of such
viscosity that the temperature needed to recycle the
reaction product when liquid and give turbulent flow
in the mixer would be high enough to result inundue
discolouration and/or formation of other byproducts.
Examples of such reaction products are those from
naphthalene compounds, alkanolamides, alkoxylated
derivatives thereof and aIkoxylated alcohols and phenols.
However, preferably the inert diluent is absent so that
no step of separating the diluent after the reaction is
needed and the final produat is substantially the
sulph(on)ated products or the main liquid contaminent
is unreacted feedstock which can be separated and recycled
for reuse.
After ~he reaction has occurred, the reaction
mixture is cooled, usually to a temperatura the same as
the input temperature of the recycle liquid before
reaction. The reaction is exothermic the heat of
reaction being absorbed in the bulk of the circulating
liquid as a heat sink. The cooling is preferably such
~s ~to qive a maximum teIilperature difference of the liquid
in different parts of the loop of 50~C especially a
- 13 -
.
.
~L~.1'7~3~
maximum difference o~ 10C. The cool:ing may take
place in one or more stages with the reaction mixture
being passed through one or more heat exchangers.
Usually the portion of reaction mixture is withdrawn
as reaction product after at least partial cooling
o~ t~e reaction liquid and the remainder is mixed
with fresh organic feedstock t:o compensate for the
organic feedstock reacted and removed, and to bring the
content of feedstock in the mixture back to the value
desired for the input feed into the reaction with
sulphur trioxide. The liquid with the content of
organic sulph(on)atable compound restored in this
~ashion is then recycled for further reaction with
sulphur trioxide. Alternatively but less preferred,
the reaction mixture may be cooled after the portion is
withdrawn, the cooling occurring before or after the
fresh feedstock is added.
The portion of reaction mixture taken out of the
system constitutes a fourtieth to a two thousandth
o~ the weight of the remainder of the reaction mixture
recycled, i.e. a recycle ratio of 40 : 1 to 2,000 : 1,
preferably 100 : 1 to 1,000 : 1, e.g. 100 : 1 to 700 : 1
and especially 150 - 650 : 1, e.g. 150 - 275 : 1 or
275 - 350 : 1.
The amount of the feedstock in the reaction
liquid depends on the nature of the feedstock, the
desired composition of the product removed from the
system, and the recycle ratio
When the feedstock is degraded by a substantial
excess of sulphur trioxide and when any unreacted
~eedstock is difficult to separate from the sulph(on)ated
- 14 -
~7~L33
product, as i~ true for most aLiphatic feedstocks
and also for example, with dodecyl benzene, the molar
ratio of SO3 to feedstock is usually 0.9 : 1 to 1.1 ; 1,
e.g. 0.9 : l to 1.05 : 1, preferably 0.93 : 1 to 1.05 : l,
especially 0.93 : l to 1.0 : 1. In these cases the
molar ratio of the amount of feedstock in the reaction
liyuid ta be contacted with SO3 to the amount of
sulph(on)ated derivative in that liquid is preferably
0.01 : 99.99 to 5 : 95 and especially about 0.1 : 99.9
to 3 : 9. When the feedstock to be sulphonated is
not easily degraded by an excess of SO3, the molar
ratio of SO3 to feedstock may be greater than 1 : 1, e.g.
in the range 0.9 : l to 2 : 1 or if unreacted feedstock
is more easily separated from the reaction product,
as with lower alkyl benaenes then the molar ratio of
SO3 to feedstock may be 0.1 : l to l : l e.g. 0.5 : l
to 0.95 : l. Molar ratios of SO3 to feedstock greater
than 1.2 : l are used when disulphonation, e.g. of
aromatic hydrocarbons is desired. The composition of
the liquid to be reacted with SO3 can vary over a wide
range. When the unreacted feedstock level in the
product removed from the system is to be kept low so
that the reaction mixture is substantially free (i.e. less
than 2%) of unreacted feedstock, ~he molar ratio of
feedstock to sulphonated derivative may be 0.01 : 99.99
to lO : 90, preferably 0.01 : 99.99 to 5 : 95, e.g.
0.1 : 99.9 to 3 : 97. When the product is to contain
a substantial amount of unreacted volatile feedstock
the molar ratio of feedstock to sulphonated derivative
may be 5 : 95 to 90 : lO, e.g. 15 : 85 to 90 : lOo
i~,
~.17~ 3
The latter proportlons may often be advantageous if
the product is to be purified for removal of sulphones
obtained with aromatic hydrocarbon feedstocks, because
the crude product can be treated with water and the
aqueOus sulphonic acid layer separated from an organic
layer comprising unreacted feeds~ock and water insoluble
impurities, such as the sulphones. The sulphur
trioxide : feedstock molar ratio is determined by the
desired composition of the product, as well as the nature
of the feedstock.
The product removed from the system can be
used as such or converted to the corresponding salt
by treatment with a base and/or puriied to remove
impurities.
Thus in the case of reaction of the aromatic
compounds with s~lphur trioxide in a molar ratio of
less than 1 : 1.2 the liquid removed from the system
comprises any unreacted aromatic compound and sulphonated
ompounds which are primarily the mono sulphonic acids
of the aromatic~compounds and inert liquid diluent (if
used in the reaction) and also may contain small a~ounts
of disulphonic acids, sulphuric acid and/or sulphones.
When the molar ratio of sulphur trioxide to aromatic
feedstock is greater than 1.2 : 1 the liquid removed
from the system comprises sulphonated compounds which
are disulphonic acids and monosulphonic acids and
inert liquid diluent (if used in the reaction), and may
also contain small amounts of unreacted aromatic
compound, sulphuric acid and/or sulphones. The sulphonic
acids may be sold as such, or after treatment with a
base to ~orm an aqueous phase comprising a solution of a sul-
phonate salt. The base may be an a~us solution of an alkali metal
- 16 -
7~
hydroxide, carbonate or bicarbonate, e~. sodium hydroxide
or sodium carbonate or ammonia or an organic amine, such
as trialkyl amine or dialkyl amine, each with 1 to 4
carbon atoms in each alkyl group, e.g. dimethylamine
or an alkylolamine, e.y. ethanolamine. Alternatively
the liquid is treated with water, optionally after adding
a hydrocarbon solvent e.g. benzene, toluene, xylene or
paraffin to cause separation into an aqueous phase containiny
the sulphonic acids and an organic phase containing unreac-
ted aromatic compound and sulphone (and the hydrocarbon
added). There is no need to add further hydrocarbon
if the product removed from the system contains a sub-
stantial amount of unreacted volatile aromatic compound,
as mentioned above or water immiscible liquid diluent.
The aqueous sulphonic acid can be used as such or converted
into a salt as described above. The treatment o~ the
crude liquid with the aqueous solution of base can also
be followed by separation of the organic phase as described
above. Traces of residual organic feedstock and hydro-
carbons can be removed from the sulphonic acid or salt
product by stripping e.g. under vacuum.
In order to minimize the production of sulphones
in the sulphonation reaction, when the feedstock is benzene
or benzene substituted by at least one alkyl chain of
1-5 carbon atoms, it is preferred to carry out the reaction
in the presence of a sulphone inhibitor.
The sulphone inhibitor is usually added with
the feedstock if it is soluble therein, but otherwise
it is added separately to the reaction liquid usually
before the addition of the sulphur trioxide. Amounts
of inhibitor of up to 10% (by weight based on the weight
- 17 -
.33
of the sulphona-ted product) may be used, e.g. up to 5~,
preferably 0.5~5% especially 1-5~. The inhibitors may
be oxygenated compou~ds, nitrogenous compounds or metal
salts. The class of oxygenated compounds includes those
described in our British Patent Specification No. 1,306,226
such as cyclic ethers, e.g. of 4-8 carbon atoms such
as dioxan or tetrahydrofuran, dialkyl ethers, e.g. of
1-4 carbon atoms in each alkyl group such as diethyl
ether, dialkyl ketones, e.g. of 3-7 carbon atoms such
as acetone and methyl ethyl ketone cycloaliphatic ketones
such as cyclo-hexanone, carboxylic acids, e.g. of 2-
6 carbon atoms such as acetic or propionic acids, esters
of these carboxylic acids, e.g. with alkanols of 1 to
6 carbon atoms such as ethyl acetate, and anhydrides
of those carboxylic acids such as acetic anhydride; acetic
acid and acetic anhydride are preferred. The class of
nitrogenous compounds includes those described in our
British Patent Specification No. 1,304,51~ and includes
mono amines e.g. of formula R3N where each R, which may
be the same or different, is hydrogen, alkyl e.g. of
1 to 6 carbon atoms, cycloalkyl, e.g. of 5-7 carbon atoms
or aryl (preferably aromatic hydrocarbyl), e.g. of 6- `
12 carbon atoms, such as ammonia, di and tri alkyl amines
such as triethyl amine and diisopropylamine, primary
aromatic and cycloalkyl amines such as aniline and cyclo
hexylamine; diamines and triamines; e.g. alkylene diamines
of 2-6 carbon atoms such as ethylene diamine and alkylene
triamines of ~-10 carbon atoms such as diethylene triamine:
heterocyclic amines such as pyridine, quinoline and iso-
quinoline; carboxylic acid amines e.g. the amide from
any primary or secondary amine mentioned above preferably
- 18 -
'7~i~3
an~onia or dimethyl amine and a carboxylic acid of 1
to 4 carbon atoms such as carbonic, formic and acetic
acids, preferably urea, dimethyl formamide and dimethyl
acetamide; amine salts, where the amine part can be based
on any of the amines mentioned above, e.g. ammonium,
and the acid part is from an inorganic acid such as hydro-
chloric, sulphuric or phosphoric acid, or an organic,
sulphonic or carboxylic acid such as aromatic hydrocarbyl
or alkyl sulphonic acids such as xylene-, toluene-, benzene-,
or methane sulphonic acids. The metal salts includes
alkali metal salts of organic or inorganic acids, which
are the alkali metal salt equivalents of the amlne salts
mentioned above.
When the sulphonated aromatic product is wanted
in its acid form, the inhibitor is preferably an oxygena-
ted compound, e.g. acetic acid or acetic anhydride because
the other inhibitors introduce often undesirable compounds
into the acid, e.g. ammonium salts. ~hen the sulphonated
aromatic product is wanted in its salt form, the presence
of ammonium salts or production of ammonia as byproducts
from, e.g. urea is of no consequence because the neutral-
ization of the free acid product liberates the amine
or ammonia, which can be separated from the salt.
The feedstock or the sulphone inhibitor (if
the latter is not added with the feedstock) may be mixed
with up to 300% (by weight of inhibitor), preferably
20-70% of water. The water appears to act as an auxiliary
sulphone inhibitor but may result in a higher percentage
of free sulphuric acid in the reaction product, which
may be desirable in certain applications. Water added
alone is a poor sulphone inhibitor and increases the
-- 19 --
~1~1'73l~3
content of Eree sulphuric acid in the reaction product
considerably. Examples of useful combinakions of inhibitor
and water are water and carboxylic acids~ esters or an-
hydrides, e.g. water and acetic acid, acetic anhydride
or ethyl acetate.
When the oxganic feedstock sulphated is a
fatty alcohol, the reaction mixture remo~ed from the
system comprises unreacted alcohol and the desired mono
alkyl sulphate (and inert diluent if present) together
sometimes with the di alkyl sulphate ester. The mixture
is usually treated with an aqueous solution of a base,
e.g. one as described above to form an aqueous phase
comprising an aqueous solution of a sulphate salt. The
amount of base is at least sufficient to neutralize the
reaction product. Similar operations may be carried
out when the feedstock is any of the other sulphatable
compounds.
The sulph(on)ated products of our invention
can be treated by any of the known techniques used to
produce saleable materials. For example, in the case
of the sulphonation of olefins having 8-20 carbon atoms
it is necessary to include a process step which results
in the hydrolysis of the sultones formed in the reaction.
Another example is that in the case of the sulphonation
of dodecyl ben~ene it may be desirable to add small amounts
of water to the sulphonic acid product in order to prevent
the colour of the sulphonic acid darkening on storage
and to prevent pH drift of salts produced from it. This
procedure is disclosed in British Patent Specification
804,349. If desired one of the process steps in the
treatment of the products of the invention can be bleaching
- l9a -
`~.
3~
by any suitable means.
In a most preEerred process, the sulph(on)ation
is carried out in a recycle loop reactor having in the
direction of flow of reaction liquid and mixture, an
inlet for feedstock, an orifice plate mixer and inlet
for sulphur trioxide together i.n a mixer comprising a
plate having an orifice, which is substantially perpendicu
lar to said plate and a port in the internal wall of
the orifice, the ratio of the cliameter of the orifice
to the thickness of the plate being 1:1 to 20:1, a pump,
a heat exchanger as cooler and an outlet for said reaction
mixture, the sulph(on)ation reaction being carried out
with undiluted gaseous sulphur trioxide and a reaction
liquid free of inert diluent at a temperature of 20-
80C under substantially no externally applied pressure
or ~m, the Reynolds Number at the point of mixing
being 10,000-15,000, the recycle weight ratio.of the
reaction mixture removed to the recycled remainder being
1:150-350, preferably 1:150-275 and, when the feedstock
is benzene or an alkyl benzene, the reaction liquid also
: contains a sulphone inhibitor in amount of 1-5% by weight
of feedstock.
The mixer of the invention can be of simple
construction and the conditions for successful operation
of mixlng and reaction processes using it on a small
scale, e.g. o at least 10 lblhr total weight of sulphur
~:: trioxide and added feedstock can be scaled up easlly
for larger scale processes, e.g. at least 200 lb~hr.
The invention may be illustrated with reference
to the accompanying drawings, in which Figure 1 represents
a flow diagram of a preferred process, Figure 2 a flow
- l9b -
33
diagram of an alternative but less preerred process,
Figure 3 represents a section through a mlxer plate,
and its associated pipework~ the section being taken
along the line AA of Figure 4 and Figure 4 represents
a section along the line BB through the mixer plate of
Figure 3.
In Figures 1 and 2 oE the drawings the loop
has an input line 1, a pump 2, a turbulent flow mixer
3, an input line 4 to mixer 3, a heat exchanger 5, and
an output line 6.
In the operation of Figure 1 the mixture of
unreacted organic feedstock and sulph(on)ated organic
feedstock (referred to hereafter as a "heel") is circula-
ted round the loop by pump 2. Fresh organic feedstock
is passed into the loop from line 1 and the mixture of
it and the heeel is rendered turbulent, so that the mixture
is turbulent at the point in mixer 3 where sulphur trioxide
enters the loop from line 4, the reaction mixture produced
is drawn through pump 2 and pumped further round the
loop through the heat exchanger 5; a very small portion
of the reaction mixture is removed through line 6 and
~ the remainder is recycled for contact with fresh organic
; feedstock from line 1. Alternatively the remainder
; of the small portion of the reaction mixture may be removed
before passage through the heat exchanger.
The operation of Figure 2 is similar, except
~ that the pump 2 and mixer 3 ar~ transposed.
; Turning now to Figures 3 and 4, conduit 7
with flange 8 is spaced from corresponding conduit 9
and flange 10 by a mixer plate 11 which has an axial
orifice 12 at its centre. The ratio of the diameter
-- l9c --
~,
7~3
of the axial orifice to the length of the orifice ls
particularly 1.63:1. From the middle of ori1ce 12 is
disposed a radial secondary port 13, the external end
of which has been drilled out for a short distance to
receive a feedpipe (not shown~.
In use a first fluicl is passed through conduit
7 and thence through axial orifice 12, where it becomes
turbulent and meets the second fluid, which has passed
through secondary port 13. The turbulent mixture of
first and second 1uids then passes further inko conduit
9. The mixer which is described with respect to Figures
3 and 4 may be used in sulph(on)ation processes, the
10w diagrams or which are shown in Figures l and 2.
The invention is illustrated by the Examples
set out in the ~ollowing Tables.
The apparatus was as shown in Figure l. The
Table gives the approximate Reynolds number at the point
of mixing the S03 and the reaction liquid, the Number
quoted being calculated on the assumption that there
is no gas phase present. In Examples 1-3, tha mixer
was one o the invention as illustrated with re~erence
to Figures 3 and 4 with a 0.87:1 ratlo of
~: :
:
- l9d -
.
.~ '33
' di~meter of orifice to plate thiclcness nnd in Ex~my1e 4 ~he r,~1xer wn~
one of the invent1on ~9 illuatr~ted with re~erence to Fi~ures 3 nnd ~J
l~ut modif1ed with a
3.5 : 1 ratio of dlameter of orifice to plnte thickness~
S The recycle ra~o quoted ~ the wei~ht r~tio of the
circulation rate to the rate of ~eedin~ the feedstock ~nd S03 into the
loop; the rate of input feed i9 the ~me as the rate of off ta1ce~
For Exa~ples l, 2 and 4 : the reaction product tak2n
from the loop at outlet 6 wa3 snalysecl ~or total acidity (by titrntion
with alkali, and expresséd as % sulphuric scid)~ % ~ree sulphuric ~cid~
sulphone, ~ free hydroc~rbon and ~ dlsulphonic ncids, The colour
.
~uoted ~as te~ t1mes the re~ding measured usin~ ~n Eel Cvlorimeter with
a * ue ~03 filt~r o~ an aqueous ~olution of the ~e~ction product,
: obtained by addin~ water to the re~ction product to gi~e a 65% by
15~ ~: weight~ aqueous golutlon of sulphonic ~cid and separating unreacted
hydrocarbon and any precipit~te o~ sulphone.
For Example 3 ~ ~he alcollol sulphated WQS ~ mixture
of fatty~loo1lo1s:in~whlch Cl2~ snd C~4 alcohoIs predo~insted~ the
~ mixture~being th~t::sold~under the Trad~ m~"Laurex I~C". ~ne
- -. 20~ ~reactio~ producé was-~n
yield 8 28% aqueouo--~olutionf~whose oolo was measured QS b
The neutrali~ed reactio~product;ws~ a1YO analyzed for total surface
acti~e~matter~;~odiu~ su1phate~and~fr~e-~fatty matter (by ether
extraction of the neutral~zed product)
-
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