DESCRIPTION
METHOD FOR PRODUCING ALKYL-BENZENE COMPOSITION AND ALKYL
BENZENE SULFONATE
Field
[0001] The present invention relates to an alkyl-benzene
composition for use in alkyl benzene sulfonate production,
the alkyl-benzene composition being capable of improving
the hue of an alkyl benzene sulfonate produced with the use
of the alkyl-benzene composition, and relates to a method
of producing the alkyl benzene sulfonate.
Background
[0002] It is known that linear alkyl benzenes useful as
detergent (C15 to C20) are manufactured on a commercial
scale by a method that includes a step of alkylating
benzene with a linear monoolefin in the presence of an acid
catalyst. Generally, the resulting alkyl benzenes are
further subjected to sulfonation to give surfactants useful
in various applications.
[0003] Examples of the method of producing an alkyl
benzene sulfonate include a method of mixing an alkyl
benzene with fuming sulfuric acid or an excess amount of
concentrated sulfuric acid (about 4 times as much in mole
as the amount of the alkyl benzene) to conduct a batch-wise
reaction for production and a method of sulfonating an
alkyl benzene with sulfur trioxide diluted with an inert
gas so as to give an alkyl benzene sulfonic acid. Another
method is known, which includes continuous sulfonation
conducted between an alkyl benzene and sulfur trioxide in
an equimolar ratio in the co-presence of an alkyl benzene
and an alkyl benzene sulfonic acid while suppressing
sulfone generation and/or the like so as to give an alkyl
benzene sulfonic acid (see Patent Literature 1, for
example)

[0004] Improvement of the hue of alkyl benzene
sulfonates has been a challenge left to be solved. To date,
several methods of improving the hue of sulfonates have
been developed. Patent Literature 2 describes an alkyl
aryl sulfonic acid containing at least 1% by weight of an'
olefin, improved in thermal stability and color stability,
and reduced in the contents of sludge and sulfuric acid.
The alkyl aryl sulfonic acid described in Patent Literature
2 is suppressed in hue deterioration that occurs during
long-term storage. However, when an olefin such as
propylene oligomers and butene oligomers, for example,
propylene trimers and propylene tetramers, is added thereto
for storage, the alkyl aryl sulfonic acid described in
Patent Literature 2 requires an additional step to.remove
the olefin at the time of shipment that follows storage.
This complicates the procedure and also presents a problem
associated with storage facilities.
[0005] Patent Literature 3 describes treatment of
sulfonic acid using an unsaturated hydrocarbon having a
number average molecular weight of about 600 to 3000.
Although it describes improvement that is likely to be made
in the hue of an purified alkyl aryl sulfonic acid, Patent
Literature 3 does not mention a hue-improving effect given
by contact with the unsaturated hydrocarbon structure.
Besides, Patent Literature 3 also requires removal of the
unsaturated hydrocarbon from the alkyl aryl sulfonic acid.
[0006] Patent Literature 4 discloses a method of
treating, with basic alumina, an organic fluoride impurity
remaining in a trace amount in an alkyl benzene that is
produced by an alkylation method using HF (hydrogen
fluoride) as a catalyst. Patent Literature 4 describes
that the organic fluoride impurity can be removed with the
use of the basic alumina, the treatment can suppress an

increase in the bromine number, and a sulfonate obtained by
sulfonation of the alkyl benzene produced by the method has
an improved hue. However, in Patent Literature 4, the
bromine number is as high as even over 0.01 according to an
increase in the Br number in an example and the sulfonate
has a very high Klett unit.
[0007] Patent Literatures 5 and 6 describe that use of
various clays and various zeolites can achieve removal of a
precursor of a substance that causes discoloration of a
alkyl benzene, before sulfonation, that is useful as
detergent. Patent Literatures 5 and 6 place a focus on a
discoloration-causing-substance precursor that absorbs
light at a wavelength of 368 nm and describe that this
discoloration-causing-substance precursor can be removed by
adsorption thereof to various clays and various zeolites.
However, Patent Literatures 5 and 6 neither describe nor
suggest a substance that absorbs light at a wavelength of
314 nm.
[0008] In recent years, mainstream linear alkyl benzenes
useful as detergent (C15 to C20) have a bromine number of
equal to or less than 0.01 and further improvement of the
hue of these linear alkyl benzenes is strongly demanded.
However, none of these patent literatures described above
mentions an impurity that remains after sulfonation of an
alkyl benzene having a bromine number of equal to or less
than 0.01 to be likely to influence the hue.
Citation List
Patent Literature
[0009] Patent Literature 1: Japanese Laid-open Patent
Publication No. 53-63346
Patent Literature 2: Japanese Laid-open Patent
Publication No. 52-102245
Patent Literature 3: Japanese Laid-open Patent

Publication No. 5-262717
Patent Literature 4: Japanese Laid-open Patent
Publication No. 5-271115
Patent Literature 5: U.S. Patent No. 4,468,476
Patent Literature 6: U.S. Patent No. 4,433,196
Summary
Technical Problem
[0010] An object of the present invention is, in
particular, to provide an alkyl-benzene composition capable
of improving the hue of a linear alkyl benzene sulfonate
for detergent application, and provide a method of
producing the alkyl benzene sulfonate.
Solution to Problem
[0011] The inventors of the present invention have
conducted intensive research to achieve the object and, as
a result, have found that an alkyl-benzene composition
having a particular range of properties improves the hue of
an alkyl benzene sulfonate. The present invention has been
thus completed.
[0012] An alkyl-benzene composition according to the
present invention is an alkyl-benzene composition for use
in alkyl benzene sulfonate production. The alkyl-benzene
composition has a UV absorbance of equal to or less than
2.98, when placed in a quartz sample holder having a path
length of 1 cm and subjected to spectrophotometry at a
wavelength of 314 nm.
[0013] In the above-described alkyl-benzene composition
according to the present invention, the absorbance at a
wavelength of 314 nm is equal to or less than 2.69.
[0014] In the above-described alkyl-benzene composition
according to the present invention, the absorbance at a
wavelength of 314 nm is equal to or less than 2.40.
[0015] The above-described alkyl-benzene composition

according to the present invention includes equal to or
more than 95% by mass of a C16-C19 alkyl benzene.
[0016] The above-described alkyl-benzene composition
according to the present invention has a bromine number of
equal to or less than 0.01.
[0017] The above-described alkyl-benzene composition
according to the present invention has a fluorine content
of equal to or less than 0.5 ppm.
[0018] A method of producing an alkyl benzene sulfonate
includes sulfonating the alkyl-benzene composition
according to any one of the above with a sulfate.
Advantageous Effects of Invention
[0019] The alkyl-benzene composition and the method of
producing an alkyl benzene sulfonate according to the
present invention can produce an alkyl benzene sulfonic
acid with an improved hue by sulfonating an alkyl-benzene
composition having a UV absorbance of equal to or less than
a specific value when measured at a specific wavelength.
Although the hue of a trace amount of a sample may be
determined by a technique of measuring UV absorbance, the
finding that regulation of the UV absorbance of an alkyl
benzene at a wavelength of 314 nm to equal to or less than
a specific value before sulfonation achieves inhibition of
the hue after sulfonation is a breakthrough.
Brief Description of Drawings
[0020] FIG. 1 is a graph depicting the relation between
the UV absorbance of an alkyl-benzene composition at 314 nm
and the Klett unit of an alkyl benzene sulfonate.
Description of Embodiments
[0021] The present invention is described below in
detail.
[0022] An alkyl benzene sulfonate that is produced using

an improved hue. In addition, when the alkyl-benzene
composition of the present invention is used, an alkyl
benzene sulfonate with little discoloration is easily-
produced. These improvements are achieved by selecting an
alkyl-benzene composition containing a low level of an
impurity that accounts for a UV-Vis absorbance at a
wavelength of 314 nm. More specifically, when measured
with a UV-Vis spectrophotometer at this wavelength, the
absorbance of the alkyl-benzene composition is equal to or
less than 2.98, more preferably equal to or less than 2.69,
and most preferably equal to or less than 2.40.
[0023] The wavelength, 314 nm, was selected for
analyzing a pure sample of the alkyl-benzene composition in
a cell "having a path length of 1 cm". Several wavelengths
of and near 314 nm can be. used when a cell having a path
length of 1 centimeter or greater is used. The absorbance
at the wavelength in question in the present specification
(314 nm) is merely an absorbance at a designated wavelength
and does not need to be an absorbance accompanied by a
maximum peak. Any analysis method for UV-Vis absorbance
measurement can be employed in the present invention.
[0024] In the present invention, a sample holder has a
path length that can vary depending on the method and the
apparatus used for analysis. However, the path length of
the sample holder needs to be long enough to allow
detection of an impurity in question contained in the
alkyl-benzene composition. The UV-Vis spectrophotometer is
simply required to be operable at the near-ultraviolet
region, which is typically 200 nm to 380 nm.
[0025] The term "alkyl benzene" in the present
specification refers to a mixture of C15-C20 alkyl benzenes.
In terms of alkyl benzenes to be used as a raw material of

commercially available products of such alkyl benzenes
typically have purity of equal to or more than 95% by mass
in terms of the contents of C16-C19 alkyl benzenes.
Accordingly, the alkyl-benzene composition of the present
invention preferably contains equal to or more than 95% by
mass of C16-C19 alkyl benzenes.
[0026] In the present invention, the alkyl-benzene
composition is produced from a monoolefin and benzene with
the use of a catalyst, in which the monoolefin is obtained
through dehydrogenation of a C9-C14 normal paraffin with
the use of a platinum catalyst. As the catalyst used to
produce the alkyl-benzene composition, HF, a zeolite,
silica-alumina, or the like is used. The method of alkyl
benzene production using HF as a catalyst is called the
Detergent Alkylation Process, where benzene and a linear
monoolefin are subjected to alkylation in the presence of
liquid hydrofluoric acid (HF). On the other hand, the
method of alkyl benzene production using a zeolite as a
catalyst is called the Detal Process, where benzene and a
linear monoolefin are subjected to alkylation in the
presence of a zeolite that is a solid catalyst. The alkyl
benzene is produced by various methods, and methods of
producing the alkyl-benzene composition in the present
invention are not limited to the above-mentioned methods.
[0027] In alkyl benzene production using HF as a
catalyst, fluorine remaining in a trace amount in the
resulting alkyl benzene is to impair the quality of the
alkyl benzene and therefore is usually decreased in amount
to equal to or less than 0.5 ppm via treatment with a solid
alumina adsorbent in a later step.
As the solid alumina adsorbent, activated alumina for
use to adsorb an organic substance can be exemplified. The

binder. Alternatively, modified alumina on which an
appropriate metal such as alkali metals and alkaline-earth
metals in such a form as the oxide or the hydroxide thereof
is supported as appropriate via impregnation or by another
method can be used provided that it can adsorb fluorine.
However, the alumina herein does not need to serve as a
support or be modified in this way, and alumina containing
equal to or less than 0.5% by weight of an alkali metal
such as sodium or an alkaline-earth metal is usually used.
[0028] The method of alkyl benzene production includes a
reaction between a monoolefin and benzene and therefore the
resulting alkyl benzene contains a trace amount of an
olefin component. The olefin component remaining in a
trace amount is to impair the quality of the alkyl benzene
and is therefore usually treated with an adsorbent such as
activated clay in a later step so as to be decreased in
amount. The amount of such an impurity can be determined
by measuring the bromine number. The bromine number is
preferably equal to or less than 0.01, more preferably
equal to or less than 0.005, and further preferably equal
to or less than 0.001.
[0029]'"" The term "alkyl benzene sulfonate" in the present
specification refers to a C15-C20 alkyl-benzene composition
sulfonated with a sulfate.
[0030] The term "pure alkyl benzene sample" in the
present specification refers to a chemical product (alkyl
benzene) that is obtained by chemical synthesis of an alkyl
benzene and subsequent purification (in one step or in
multiple steps) of the synthesized alkyl benzene and that
contains no additional artificial chemical substance (s)
obtained by a process other than the chemical synthesis or
the purification (in one step or in multiple steps).

refers to one or more compounds that are not chemically
equivalent to the alkyl benzene but have a UV absorbance at
a wavelength of 314 nm measured via UV-Vis absorbance
spectrometry. The inventors of the present invention found
that such an impurity can be removed by purification in
contact with an inorganic compound or by distillation.
[0032] (Distillation)
The purified alkyl-benzene composition according to
the present invention that is purified so as to have a UV
absorbance at 314 nm of equal to or less than 2.98 may be
obtained by thermally distilling an alkyl-benzene
composition containing a trace amount of impurity under an
appropriate pressure.
[0033] The distillation can be performed by any method,
for example, by a batch method or a continuous method.
[0034] (Adsorbent contact treatment)
Alternatively, the purified alkyl-benzene composition
according to the present invention that is purified so as
to have a UV absorbance at 314 nm of equal to or less than
2.98 may be obtained by a process called the adsorbent
contact treatment in which the alkyl benzene containing a
trace amount of impurity is brought into contact with an
adsorbent.
[0035] The. adsorbent contact treatment is performed, for
example, by bringing the alkyl-benzene composition
containing a trace amount of impurity into contact with an
adsorbent such as alumina (Al2O3) , activated clay, silica,
and a zeolite. The alumina and the activated clay for use
to remove one or more compounds having a UV absorbance at a
wavelength of 314 nm can be alumina and activated clay used
for removal of HF and olefin.
[0036] The adsorbent used herein has a particle diameter

from 2 to 4 mm and has a specific surface area within the
range usually from 50 to 500 m2/g and preferably from 200
to 500 m2/g.
[0037] After the alkyl-benzene composition containing a
trace amount of impurity is brought into contact with the
adsorbent, the alkyl-benzene composition can be separated
from the adsorbent by a method such as filtration or
adsorbent precipitation followed by recovery of the
supernatant.
[0038] When the alkyl-benzene composition that is
purified by the distillation treatment and/or the adsorbent
contact treatment so as to have a UV absorbance at a
wavelength of 314 nm of equal to or less than 2.98 is used
as a raw material of the alkyl benzene sulfonate, the
resulting alkyl benzene sulfonate has little discoloration
and excellent quality, compared to when a commercially
available alkyl benzene is used as it is. The reason seems
to be that an impurity contained in the commercially
available alkyl benzene to influence discoloration during
sulfonation can be removed by the purification.
[0039] (Determination of bromine number)
The bromine number in the present invention is
determined by the electrometric titration method in
conformity with JIS K2605 (petroleum products, method of
determining bromine number, electrometric titration method).
[0040] (Determination of fluorine content)
The fluorine content in the present invention is
determined by ion chromatography.
Examples
[0041] The present invention will be described in more
detail by the following examples. The scope of the present
invention, however, is not limited to these examples.

Using a C9-C14 normal paraffin mixture and benzene as
raw materials and liquid HF as a catalyst, an alkyl benzene
was produced. This was followed by treatment with alumina
(PSG-A25 manufactured by Axens) and clay (activated clay:
Galleonite 251 manufactured by Mizusawa Industrial
Chemicals, Ltd.) (treatment temperature: 70°C) and
purification by distillation. The resulting alkyl benzene
containing equal to or more than 95% by mass of C16-C19 and
having an average molecular weight of 240 to 244, a bromine
number of equal to or less than 0.01, and an F content of
equal to or less than 0.5 ppm was collected in the form of
5 samples (Examples 1 to 3, Comparative Examples 1 and 2).
Each sample was subjected to absorbance measurement at 314
nm with a UV-Vis spectrophotometer. Each alkyl-benzene
composition was also subjected to sulfonation, and the
resulting alkyl benzene sulfonate was subjected to Klett
unit measurement. The results are listed in Table 1.
[0043] (Experiment 2)
Samples were collected in the same manner as in
Experiment 1, and each sample was subjected to absorbance
measurement at 314 nm with a UV-Vis spectrophotometer.
Each alkyl benzene was also subjected to sulfonation of
alkyl benzene, and the resulting alkyl benzene sulfonate
was subjected to Klett unit measurement (Comparative
. Example 3).
[0044] (Experiment 3)
Each sample in Experiment 2 was subjected to another
round of distillation to obtain a sample from which 3% of
light components and 3% of heavy components had been
removed. The resulting samples were subjected to
absorbance measurement at 314 nm with a UV-Vis
spectrophotometer. Each alkyl benzene was also subjected

benzene sulfonate was subjected to Klett unit measurement
(Example 4).
[0045] (Experiment 4)
Samples were collected in the same manner as in
Experiment 1 except that no clay treatment was performed,
followed by absorbance measurement at 314 nm with a UV-Vis
spectrophotometer. Each alkyl benzene was also subjected
to sulfonation of alkyl benzene, and the resulting alkyl
benzene sulfonate was subjected to Klett unit measurement
(Comparative Example 4).
[004 6] (Experiment 5)
Each sample in Experiment 2 was repeatedly treated
with activated clay, and the resulting samples were
subjected to absorbance measurement at 314 nm with a UV-Vis
spectrophotometer. Each alkyl benzene was also subjected
to sulfonation of alkyl benzene, and the resulting alkyl
benzene sulfonate was subjected to Klett unit measurement
(Example 5).
[0047] (UV-Vis analysis)
A pure alkyl benzene sample was put into a quartz
cuvette having a path length of 1 cm and was then subjected
to analysis with a UV-Vis spectrophotometer. The analysis
was performed against an air blank, in other words, no cell
was placed in the blank compartment. A UV-Vis spectrum was
collected on SHIMADZU UV-2550 UV-VIS SPECTROPHOTOMETER.
Using the spectrophotometer, a UV-Vis absorbance spectrum
from about 200 nm to about 800 nm was recorded and a
numerical value indicating the absorbance at 314 nm was
output. Typically, an absorbance at 314 nm appears at a
shoulder of a significantly intense peak. Accordingly, the
absorbance at 314 nm is merely an absorbance measured at a
designated wavelength and does not need to be an absorbance

[0048] (Alkyl benzene sulfonation and Klett unit
measurement)
Referring to a method described in Example 1 of
Japanese Patent Application Laid-open No. 2008-94941, an
alkyl benzene sulfonate was synthesized. The resulting
alkyl benzene sulfonate was prepared into a 10% ethanol
solution thereof, which was then put into a 10-mm sample
cell to be subjected to absorbance measurement at a
wavelength of 420 nm with a spectrophotometer with the use
of ethanol as a control. The resulting absorbance was
multiplied by a coefficient of 1000 (to give a Klett unit).
The relation between the absorbances of all the alkyl
benzene samples and the Klett units of the alkyl benzene
sulfonates are listed in FIG. 1.
[0049]



[0051] As is evident from Table 1, when the alkyl-
benzene composition according to the present invention, in
other words, an alkyl-benzene composition having a UV
absorbance at 314 nm of equal to or less than 2.98 measured
via UV-Vis absorbance spectrometry was used as a raw
material, the resulting alkyl benzene sulfonate had a lower
hue. FIG. 1 confirmed that the absorbance at 314 nm had a
strong correlation with the hue. The Klett unit of an
alkyl benzene sulfonate for detergent applications can be
equal to or less than 40 for commercial use, but it is more
preferably equal to or less than 30 and is most desirably
equal to or less than 20.

CLAIMS
1. An alkyl-benzene composition for use in alkyl benzene
sulfonate production,
the alkyl-benzene composition having a UV absorbance
of equal to or less than 2.98, when placed in a quartz
sample holder having a path length of 1 cm and subjected to
spectrophotometry at a wavelength of 314 nm.
2. The alkyl-benzene composition according to claim 1,
wherein the absorbance at a wavelength of 314 nm is equal
to or less than 2.69.
3. The alkyl-benzene composition according to claim 2,
wherein the absorbance at a wavelength of 314 nm is equal
to or less than 2.40.
4. The alkyl-benzene composition according to any one of
claims 1 to 3, comprising equal to or more than 95% by mass
of a C16-C19 alkyl benzene.
5. The alkyl-benzene composition according to any one of
claims 1 to 4, wherein the alkyl-benzene composition has a
bromine number of equal to or less than 0.01.
6. The alkyl-benzene composition according to any one of
claims 1 to 5, wherein the alkyl-benzene composition has a
fluorine content of equal to or less than 0.5 ppm.
7. A method of producing an alkyl benzene sulfonate, the
method comprising sulfonating the alkyl-benzene composition
according to any one of claims 1 to 6 with a sulfate.