CA1086777A

CA1086777A - Process for removing unwanted acid substances from reaction products

Info

Publication number: CA1086777A
Application number: CA272,647A
Authority: CA
Inventors: Mitsuo Okazawa; Tetsuya Takezono
Original assignee: Nippon Oil Corp
Current assignee: Eneos Corp
Priority date: 1976-02-27
Filing date: 1977-02-25
Publication date: 1980-09-30
Also published as: JPS6031522B2; JPS52103390A; GB1570932A; DE2707765A1; FR2342262B1; FR2342262A1; NL7702053A

Abstract

ABSTRACT OF THE DISCLOSURE
In reactions catalyzed with a sulfonic acid-type cation exchange resin such as n reaction of obtaining an ether from an olefinically unsaturated hydrocarbon and an alcohol, a reaction of obtaining an alcohol by hydration of an olefinically unsaturated hydrocarbon, or a reaction of obtaining a polyhydric alcohol ether from an olefinically unsaturated hydrocarbon and a polyhydric alcohol, the reaction produce contaminated by free sulfonic acid or sulfuric acid ascribable to the catalyst used in the reaction is contacted with hydrotalcite thereby to remove the free sulfonic acid or sulfuric acid from it.

Description

~his i~ention rela~es to a process ~or remo~i~g unwanted acid substances from a reaction mixture ~btai~ed bg a reaction catalyzed by a ~ulfonic acid-type oation exchange xes~n.
Many reactions catalyzed by sul~onic acid-~ype cation exchange resins have been known, and utilized in the industrial production of chemical compounds. I~
these catalytic reactions, acid substa~ces su¢h as free aro~atic sulfonic acid or sul~uric acid containe~ i~ the sulfoni~ a~id-type cation exchange resins tend to be entrained in the reaction product as a result of extxaction or liberation thereinto, and this conseque~tly causes various troubles.
Processes for producing compounds commercially by such catalytic reactions frequently resort to the pra~tice o~ performing the reaction u~der conditio}~ ~uc}~ ;
that the unreacted starting mixture will be pre~e~t in a co~siderably high conceI~tration in the reaction sys~dm in order to increa~e the rate o~ reaction or inhibit side-reactions. l`he resulting reaction mi~ture is sepa- .
rated into the de~ired final product and the unreacted ~ -starting mixture b;y di~tillation, extraCtion or àdsorptioD.
the latter being recycled to ~hc reaction systeT~. If the reactiQn mi~tUre containing the sul~onic acid-type catio 25 ~ e~rchan@;~ resiD iS tQ be separated by distillatio~ i~ 5uCh sep~ra~ing 8tep, a backward reaction or other side-reactions: wlll take place by the effect of heat. If, o~ the other h~v~d, the separation is effecte~ b~
extraction~ or adsorption, the acid subs~ances will impair .

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;'77~
the extracting agents or adsorbents.
Gen0rally, strongly acidic substances are re-moved by neutralization with strongly basic substances such as sodium hydroxide, calcium oxide, or calcium hydroxide.
It is dif~icult, however, to separate salts formed as a result o~ neutralization reaction, and moreover, the quantity of a basic substance to be added is consider-abl~ di~ficult to determine since the concentration of the effluent acid varies greatly according, for - - -example, to the type of the catalyst, the temperature of the reaction, the type of the raw material, the flow rate of the effluent acid, and the reaction time.
It is also possible to use ordinary adsor-bents capable of adsorbing acids, such as activated carbon, activated terra alba or silica-alumina. But these adsorbents have only a low adsorbing capacity, and a decrease in the concentration of an acid to be adsorbed results in a marked reduction in the acid-adsorbing ability of the adsorbents.
Accordingly, it is an object of this invention ~ -:
; to provide a process which can overcome the disadvantages o~ the prior art methods, and which can easily remove -~
unwanted acid substances substantially completely from a reaction product mixture containing them.
As a result of extensive investigations in order to achieve the object of the invention, the present inventors have found that hydrotalcite has an excellent ability to remove acid substances from reaction mixtures ., ,'.. '. '' '.

- 3 -,.:
.~ ' which result from reactions catalyzed with sulfonic acid-type cation exchange resins.
The present invention provides a process for separating unwanted free sulfonic acid or sulfuric acid rom a reaction mixture obtained by a reaction catalyzed with a sulfonic acid-type cation exchange resin and containing the reaction product, the unreacted starting materials, the unwanted free sulfonic acid or sulfuric acid from the ion-exchange resin, and a reaction solvent if used; which comprises contacting the reaction mixture with hydrotalcite to transfer the unwanted free sulfonic acid or sulfuric acid into the hydrotalcite, separating the reaction mixture from which the free sulfonic acid or suluric acid has been removed, and recovering it.
The process of this invention is completely free from the defects of the prior art methods descrlbed a~ove. Sulfonic acid or sulfuric acid extracted or liberated from a sulfonic acid-type cation exchange resin is almost completely transferred into hydrotalcite, and removed from the reaction mixture. Thus, a reaction mixture not containing the unwanted sulfonic acid or sulfuric acid can be recovered. As a result, all the ;
inconveniences in the step of recovering the reaction product and subsequent steps can be eliminated.
The mechanism by which acid substances from the sulfonic acld-type cation exchange resin migrate from the reaction mixture to hydrotalcite has not been clearly -known. It is presumed however that these acid substances are elther adsorbed to hydrotalcite or react with it, .

- 4 _ ~
.: . '~ . . .
:' or bo~h of these phenomena take place.
The sulfonic acid-type cation exchange re~in, as referred to in the present invention, includes~ for example, styrene-derived sulfonic acid-type resinq, and phenolsulfonic acid-type resins. The styrene-derived sulfonic acid-type ion-exchange resins are obtai~ed by sulfonating resins resultin~ from the copolymerization of styrene with a compound con-taining at least two e-thylenically unsaturated groups in the molecule, such as divinyl benzene, and usually have units represented by the following formulae.
.:

] ~:
and _ ~--- C--C~
~ rxÇ~
_ C--C _ ,. .
15~he phenolsulfonic acid-type resins are usually obtai~ed by condensing phenolsulfonic acid wi~h ~ormaldehyde, and have the foIlowing chemical structure. -;
OH -t aHz~ aH2 ¦-- .H~ n ~ ~

~

'; ~

;'7~7 ~whereln n represents the degree of polymerlzation) Hydrotalcite used in this invention is also called manasseite and is an ore of a hydrous basic carbonate of magnesium and aluminum wi~h impurities which occurs naturally in small quantities in the Ural district of U.S.S.R., for example. Hydrotalcite normally has the follow-ing chemical structure.

g6 2~ )16 3 2 or -A1203.6MgO~C02.12H20 ,, Hydrotalcite c~n be synthetically prepared.
One example of the method of synthesls is disclosed in -"Nippon Kagaku Kaishi", Vol. 92, p. 514, 1971~ and comprises continuously feeding an aqueous solu~ion of aluminum sulfate, an aqueous solution of magnesium chloride or magnesium sulfate, and an aqueous solution of sodium carbonate into a reactor, stirring the mixture, and further ~ -feedlng sodium hydroxide into the reactor so as to maintain the pH o~ the solution at 10-11. By varying the rates of feeding the aqueous solution of aluminum sulfate and the aqueous solution o~ the magnesium salt, double oxides of varying MgtAl ratios can be obtained in the suspended state. The double oxides are collected by filtration, washed with water, and calcined at 500 to 700C to afford synthetic hydrotalcites.
Usually, hydrotalcite has a magnesium/aluminum molar ratio o~ a~out 3, and is characterized by showing the followlng peaks in its X-ray diffraction pattern C~PCD 14-191~.
-~.~136777 dA I/I
7. 69 100 3. 88 70 2~ 30 20 1,96 20 1 . 85 10 . - . .
. . 1~ 75 10 ~
1 . 65 10 .
1.53 20 .: - .-1,. 50 20 1. 28 10 ~ :
RadO FeK~?~1.93728, Filter Mn.
: -~he X-ray diffraction chart o~ hydrotalcite is ~
shown in the accompanying drawingO ..
Sgnthetic h~drotalcites have a magnesium/aluminum ;~ :
mole ratio o~ 1 to 10 showing con~siderable fluo~uations from about 3O Notwi~hstandlng this, some of them show ` ~.
the X-ray di~fraction pattern which LS characte~i~tio of hydrotaloite having a magnesium/aluminum, ~oie; ratio of about 3. Such synthetlc hydrotalcltes are within the : ;
definition of hydrotalcite in thi,s invention e~eD if their magneslum/aluminum mole r~tio deviates from abou~ -~
! 3, and can be used to remove a~d substances in accordance ~5 with ~he present invention.
~ here is no particular restriction on the types of reactlons~ oatalyaed with sulfonlc acid-t~pe catlon exohànge:~res m s~to give~reaotion mi~tures ~rom which ; ~unwanted a¢id sub:tances oan b~:~r`~moved by the process .

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~)8~i~77 of this i~ventionO
Examples o~ such catalytic reaction~ are listed below.
- (1) Production of ethers from olefinicall~ :
unsaturated hydrocarbons and alcohols. --:
. (2) Production of alcohols by hydration of olefinically unsaturated hydrocarbons.
(3) Production of polyhydric alcohol ethers, especially ~lycol monoethers, ~rom olefinically -unsaturated hydrocarbons and polyhydric alcohols.
(4) Production of cyclic ethers by dehydrocycliza-tion of diglycols.

(5) Production of alkyl ar~matics by alkylation of aromatic compounds.

(6) Oligomerization of olefinic hydrocarbons.

(7) Isomerization of olefinic hydrocarbo~s for shifting their unsaturated bonds,

(8) Isomerization of hydrocar~ons to pro~ide -produc~s havinæ a skeleton with a higher degree of br~n~hing~
(9~ Aldol condensation of keton0~ and~ar aldehydes, All of the reactions exem~lified above axe essentially ba~ed on the catalytic action of the sulfone ~roup ~R-S0~ ~ ~ of the catalyst, and as a result o~ :
contacting of the reactants with the catalyst~ free aromatic sulfoni.c acid or sulfuric acid is liberated or i extracted into the reaction mixture obtained. ~he amount of unwant~d acid substances contained in the reac-tion mixture di~fers according to the reaction conditions, bUt .. ..
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. generally it is from about 100 to about 1000 ppm~
Raw materials used in the above-exemplified reactions are as follows: In reaction (1), olefinically uns~urated hydrocarbons containing 2 ~o 22 carbo~ atoms, - 5 preferably 3 to 10 carbon atoms, such as propylene, n-butene, i-bu~ene, pentene, hexene or octene, and alcohols containing 1 to ~2 carbon atoms, preferably 1 to 20 car~on atoms 9 such as methanol, ethanol, n-propanol, i-propanol, n-bu~anol, sec-butanol, hexanol, octanoll and - 10 olegl alcohol, are used. In reaction (2), the same olefinically unsaturated hydrocarbons as in reaction (1) ~
are used. In reaction (3), the same olefinically unsaturated hgdrocarbons as in reactioD (1), and polyhydrio alcoh~ls co~taining 1 to 32 carbon atoms, preferably 1 to 20 carbon atoms, such as ethyle~e glycol, 1,2-propylene glycol, gly¢erin~ diethylene glycol or triethylene gl~col, are used. In reaction (4)1 diglycols havin~ 1 to 32 ca~Son ~-atoms, preferably 1 to 20 carbon atoms, such as diethyle~e glyool, dipropylene ~lycol or dibutglene glycol, are used.
In reaction (5), monocyclic or polycyclic aromati¢
compounds containing 6 to 30 carbon atoms, such as be~zene7 ~ toluene, xylene, cumene, tetralin, naphth~lene, anthracene~
trimethylbenzene, or tetrameth~l benæene9 are used.
Examples of the alkylating agents used in reaction (5~
~re ole~inically unsaturated hgdrooarbons containing 2 ; to 22 carbon atoms, pre~erably 3 to 15 carbon atoms, such as propylene, n-butene~ i-butene, pentene, hexene, decene~
or dodecene, and saturated halides containi~g 1 to 22 carbo~ atoms, pre~erably 1 to 15 carbons toms, such as :` . "

9 -~:
'~

: , , . , . , ~-.

meth~l chloride, meth~l ~romlde, ethyl bromide, propyl chloride, hut~l chloride, and dodecyl chloride~ In reaction ~6), the same olefinically unsaturated hydro-carbons are used. In reaction ~7), olefinic hydrocarbons containing 4 to 22 carbon atoms, preferably ~ to 10 carbon atoms, such as butene-l, pentene-l or heptene-l, are used. In reaction ~8), aliphatic or clicyclic saturated hydrocarbons containing 4 to 22 carbon atoms, such as butane, pentane, heptane or decane, and various petroleum fractions containing them, especially petroleum fractions used for gasoline, are employed. The raw materials used in reaction ~9) are ketones or aldehydes containing 1 to 20 carbon atoms, preferably 2 to 8 carbon -atoms, such as acetaldehyde, acetone, propionaldehyde, and butyraldehyde.
The reaction conditions differ according to the type o~ reaction. In view of the catalytic nature of sulfonic acid-type cation exchange resins, ths reaction is carried out usually at 0 to 250C, preferably 50 to 150C. Temperatures outside this range are not preferred since at below 0C, none of the aforesaid reactions proceed 0ffectively, and at more than 250C, the raw materials and the sulfonic acid-type cation exchange resins ` are liable to be decomposed. The reaction pressure may be reduced pressures, but usually, normal atmospheric pressure to 50 atmospheres, preferably atmospheric pressure to lO atmospheres, are employed.
The materials to be contacted with the catalyst I may be in t~e form of gas or liquid. Preferably, the ~ ~
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. ~. . .
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catal~st is pac~ed in a la~er, and the materials in fluid form are passed through it. There can also be employed a method in which the catalyst is suspended in the fluidic materials, or a method in which the fluidic materials are contacted with the catalyst fluidi~ed by the materials.
The reaction mixtures obtained by the reaction - -Cl) of producing ethers from olefinically unsaturated hydrocarbons and alcohols, the reaction (2) of producing alcohols b~ hydration of olefinically unsaturated hydro carbons, and the reaction (3) of producing polyhydric alcohol ethers from olefinically unsaturated hydrocarbons and polyhydric alcohols are especially suitable for re-moval of unwanted acidic substances by the process of the present invention.
Examples of the reaction (1) are a reaction of obtaining ~iisopropyl ether from propylene and isopropyl alcohpl, a reaction of obtaining methylisobutyl ether from isobutylene and methyl alcohol, and a reaction of obtaining isopropyl tertiary butyl ether from isobutylene and iso-propyl alcohol.
These reactions are p~rformed by contacting the reactants with a sulfonic acid-type cation exchange resin catalyst usually at a temperature of 20 to 200C, preferabl~ 50 to 180C, and a pressure of 0 to 50 atmospheres.
These reactions are described, for example, in British Patent No. 957,000 and west Cerman OLS. No. 2,403,19~.
Examples of the reaction (2) are a reaction of " obtaining isopropyl alcohol by reacting propylene with ., .

; ~ - 11 -- .-: :

. . . . ~ . : . . :
. .. . . .. : . . . .
.. . . . . .. . . . . .

~0136777 water, and a react~on o~ o~taining tertiar~ butyl alcohol br reacting Iso~ut~lene with water.
These reactions are performed by contacting the reactants ~ith a sulfonic acid-type cation exchange resin catalyst usuallly at a temperature of 50 to 200C and a pressure of O to 50 atmospheres.
These reactions are described, for example, in west German Patent No. 2,147,737.
Examples of the reaction ~3) include a reaction of bbtaining ethylene glycol monoisopropyl e~her from prop~lene and ethylene glycol, a reaction of obtaining ethylene glycol monoisobutyl ether from isobutylene and eth~lene glycol, and a reaction of obtaining diethylene glycol monoisopropyl ether from propylene and diethylene glycol.
Theise reactions are performed by contacting the reactants with a sulfonic acid-type cation exchange resin catalyst usually at a temperature of O to 150C, preferably 30 to 120C and a pressure of O to 20 atmospheres.
These reactions are described, for example, ln west German OLS Na. 2,450,66~.
In *he catalytic reactions exemplified above to which the process of the present invention can be applied, a mixture containing the unreacted materials and a reaction solvent ~if used) as well as the desired reaction product is usually withdrawn from the reac~ion zone in ~ ;~
the form containing undersired acidic substances which have been liberated or extracted firom the catalyst. ---According to the present invention, the above reaction ~-~
' .

.

~.~8f;777 mixture can be directly contac-ted with hydrotalcite.
If desired, prior -to contacting with hydrotalcitel any matter which can be readily removed by a simple operation such as standing may be removedO Where the reaction mixture contains the catalyst as a solid$ it is preferably removed before contact with hydrotalcite.
A preferred method of contact is to pass the reaction mixture to be treated through a layer packed with hydrotalcite as in the case of the catalytic reactions described hereinabove. Or;hydrotalcite can be contacted in the ~orm suspended in, or fluidized by, the fluidic reaction mixture~
H~drotalcite can be used as a powder or as particles having a particle diameter of up to about 10 mm.
~or example, it can be used in the form of spheres or cylinders (extrudate)O ~here is no particular limitatio~
on the temperature at which the reaction mixture is contacted with hydrotalcite. For example, contacting temperatures of about O to 300C, pre~erably O to 15~~, can be employed. Accordinæ to the present i~vention~
contacting of the reaction mixture with hydrotalcite results in the transfer of almost all acid substances from the reaction mixture to hydrotalcite. ~he amount of hydrotalcite can be adjusted depending upon the acid conoentration o~ the acidic solution containing acid substances to be removed. In a batchwise method, h~drotalcite is added usuall~ in an amount of 0.1 to 5~/0 by weight, preferably 1 to 2~o by weight~ to the acidic solution, In a flowing method, the acidic solution is ' '. ' 7~7 passed at a rate of 1 to 1000 g, preferably 10 to 100 g, per gram o~ h~drotalcite per hour.
~he following examples illustrate the process of this invention more specifically.
Example 1 90 g of a propylene/propane mixture containing 5~/O by weight of propylene was li~uefied under pressure, and mixed with 1 mole of isoproyl alcohol. To the -resulting solution was added 10 g of a styrene-derived B lo sulfonic acid-type cation exchange resin (AMBER~IST 15, ~, a product of Rhom & Xaas)1 and the mixture was allowed to stand at 100C for 1 hour in a stirred reactorO After the reaction, the cation exchange resin was removed by filtration. ~hus, a solution consisting of isopropyl -alcohol and diisopropyl ether was obtained. The acid concentration of this solution was loO x 10-~ eg/~

10.0 g of powdery hydrotalcite (synthetic hydrotalcite having the composition Mg6A12(0H)16.C03~4E20) was added to this ~ol~tion, and the solutio~ was stirred for 10 minutes.
20 Hydrotalcite was then removed by filtration to afford a ' neubral solution having an acid concentration of 1,2 x 10 7 e~/l. Distillati~n of the resulting ~eutral solution ~fforded 48,5 g of diisopropyl ether having a purity of 99.~/0~ From the bottom of the distillation tower, ths unreacted isopropyl alcohol was recovered.
Examp,le ?
0ne mole of prop~lene and 1 mole of methanol were liguefied under pressure and mixed. ~o the resultin~
sQlution was added 15 g of a phenolsulfonic acid-type io~
~ T~ k ~.~,.. . ...
~ - , .. .

.. : . :. - .

~ ~8~777 exchange resin (Amberlite IR~ and the mixture was allowed to stand at 85C for 2 hours in a stirred reactor. After the reaction, the cation exchange resin was removed by filtratio~, ~husl 70 g of a mixture of methanol and methyl isopropyl ether was obtained. ~he acid concentration of this solution was 2~1 x 10-2. ~o -the resulting solution was added 0.8 g of hydrotalcite (synthetic hydrotalcite havin~ the composition Mg6A12(0H)16 C03~4H20) 9haped into cylindrical fragments having an average diameter of about 0~8 mm and an average length of about 1 mm, and the solution was stirred for 30 minutes~ Hydrotalcite was then removed by filtration to afford a neutral solution having an acid concentration of 2.2 x 10-7 eg/~. ~imple distillation of ~;~
the resulting solution gave 55 g of methyl isopropyl e~her -having a purity of more than 99O~,~o ExamP~e ~
The unreacted isopropyl alcohol recovered in Ex~ple 1 ~as again reacted under the conditions set ~orth in Example 1. ~o deterioratlon of the catalyst was obser~ed~
and the same results as in Example 1 were obtained.
Exam~le 4 A cylindrical reactor having an inside di~meter of 5 cm and a height of 20 cm was charged with 200 g of the same styrene-derived sulfonic acid-type cation exchange resin as used in Example 1~ A starting mixture consisting o~ 1 mole of isopropyl alcohol and 140 g of mixed butylene containiDg isobutylene with a purity of 40~ iD the liguefied state under pressure was passed at a flo~ ra~e of 2,000 g/hr at 50C through the reactor packed with the ~ r~d~ k ` - 15 -.
~', `

~.~38~

cation exchange resin. '~he ef'fluent from the reactor was passed through a neutralizing pot filled with 20 g of the same hydrotalcite as used in Example 2. Then, the ~eutxalized effluent was distilled.
In the above procedure, the conversion of isopropyl alcohol was 98%~ and isopropyl tertiary butyl ether having a purity o~ more than 99~7% was obtained.
~urther~lore, in the above procedure, the acid concentration of t-he effluent from the reaction before passage through the neutraiizing pot was ~ x 10 3 eg/l, ~ :
and that after passage was 1.1 x 10-7 eg/l.
Example 5 , A starting mixture consisting of 62 g of ethylene glycol and 1 mole of isobutylene was liguefied under pressure, a~d passed in-to a reactor charged in advance .
with 15 g of a styrene-derived cation exchange resin (ob~ained by sul~onating a copolymer of styrene and ~J0 divinyl benzene and being in the form of particles having a particle diameter of 20 to 50 mesh). With stirring, the mix~ure was allowed to stand at 50C for 5 hours~
~hen, the cation exchange resin was removed. Five ~ram~
of the same hydrotalcite as-used in Example 1 was added to the remaining sol~tion having an acid concentration of 1~0 x 10-' eq/l, and the solution was stirred for ~0 . 25 min~tes, Then, hydrotalcite was separated, and the / :
remaining neutral solution having an acid concen~ration of 3.0 x 10 7 eq/l was distilled. ~he conversioD of ethylene glyoo~ was 98%, and ethylene glycol mono(tertiary~butyl~
eth~r ~aving a purity of more than 9~/0 was recovered.

.~ ..
- 16 - - ~

~ ' .

67~7 Exampl e 6 A starting mixture consisting of 1 mole of prop~lene gl~col and 1 mole of prop~lene was liquefied under pressure, and passed at 90C at a rate of 2,000 g/hr into a cylindrical reactor having an inside diameter of 5 cm and a height of 20 cm which had been packed with 220 g -of a styrene-derived sulfonic acid-type cation exchange resin ~obtained hy sulfonating a copolymer of st~rene and 10% of divinyl benzene and being in the form of particles having a particle diameter of 20 to 50 mesh). The effluent from the reactor was passed through a cylindrical neutral-izing pot packed with 100 g of the same hydrotalcite as used ln Example 2. Subsequent distillation afforded prop~lene glrcol monoisopropyl ether having a purity of 9~.5%. The ratlo of recovery of this product was 98%.
In the above procedure, the acid concentration of the effluent from the reactor was 5 x 10 3 eg/Q before flashingS 4 x 10 3 eg/~ after flashing, and 1.1 x 10 7 e~/~ after neutralization.
2n Comparative Example When the reaction mixture obtained by the re-actlon shown in Example 6 was distilled without treatment with hydrotalcite, the ratio of recovery of propylene glycol monoisoprop~l ether formed as a result of the reaction was onl~ 17%.
As a result of distillationj about 4.8 moles of prop~lene per mole of the propylene glycol monoisopropyl ether recovered was obtained from the top of the distil-lation to~er. At the bottom of the tower, propylene ~6'~ 7 ~lycol was deposited in an amount almost equimolar to propylene.
Example 7 A starting mixture consisting of 1 mole of propylen~ and 20 moles of water was passed at a flow rate of 300 g/hr at 100 to 120C th~ou~h a c~lindrical reaetor having an inside diameter of 5 cm and a height of 20 cm which had been packed with 220 g of the same cation exchange resin as used in Example 1. The reaction solu~iou had an acid concentration of 2.5 x 10 ~ eg/l. The reactîon ~ ~
solution was passed at a flow rate of 2,000 g/hr throu~h a ~ -;
cylindrical neu-tralizing pot packed with 100 g of the same hydrotalcite as used in Example 20 The acid concentration ~
of the resulting solution was 1~6 x 10-7 eg/l 9 ' ' Example 8 A 200 ml. stainless s~eel vessel eguipped with ~ -a stirrer was charged with 80 g of diethylene glycol and 30 g of a styrene-derived sulfonic acid-type ca~ion ~ exchan~e resin (AMBER$IS~ 15), and with stirring at 130C
`~ 20 the reactlon was performed for 10 hours. Af~er the reaotion, the reaction solution was filtered to remove the cation exchange resin. ~he resul~ing solu~ion had an a~id concentration of 5.7 x 10 1 eq/l. To the resulting solution was added 10.0 ~ of the same hydro~alci~e as used in Example 1, and the solution was stirred for 15 minutes. H~drotalcite was then removed by filtration to afford a neutral solution having an acid concentratio~
of 1.1 x 10 7 eq/~ Distillation of the resulting neutral solution afforded 52 g of p-dioxane having a purity of 99.~/o.

.
' .~ :

Exam~le g A 200 ml Klass flask eguipped with a refl~x co~-denser and a stirrer was charged wi-th 20 g of a styrene-derived sulfonic acid-type cation exchange resin (AMBERLIST 15) and 60 g of p-xylene. Gaseous propyle~e was passed into the solution -through a blowing tube at a flow rate of 400 ml/min., and reacted for 3 hours.
After the reaction, the reaction mixture was filtered to remove the cation exchange resin. As a result, 2.5-diisopropy-1,4-dimethylbenzene was obtained in a yield of 99% with a p-xylene conversion of 10~/o. The resulti~g solution had an acid concentration of 2.5 x 10 1 eg/l, and to this solution was added 500 g of the same hydrotalcite as used in Example 1, ~he solution was stirred for 15 minutes, and hgdrotalcite was removed by filtration, A neutral solution having an acid concentration of 1.5 x 10-7 eg/~ was obtained, Example 10 A l-liter stainless steel vessel eguipped wi~
, ~
- 20 a stirrer was charged with 125 g of a styrene-derived sulfonic acid-type cation exchange resi~ (AMBERLIS~-15)~
195 ~ of benzene and 86 g of a mixture o~ n-olefins havin~ 10 to 14 carbon atoms, and with stirring at 120C, the reaction was performed for 6 hours. Af*er the ~5 reaction, the reaction mixture was filtered to remo~e the cation exchange resln, A chromatographic analysis of the resulting solution showed ~hat 88~ of the starti~g n-olefin mixture had been converted to alkylbenzenesO
This solution had an acid concentration of 3.0 x 10~1 eq/l.

` - 19 .. .: :, ~o ~he solution was added 15.0 ~ of the same hydrotalcit~
as used in Example 1, and the solution was stirred for - -30 minutes. ~hen, hydrotalcite was removed by filtration to afford a neutral solution havi~g an acid concentrati~
o~ 1.3 x 10-7 eg/l, - 20 - `

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Claims

WHAT WE CLAIM IS:

1. A process for separating unwanted free sulfonic acid or sulfuric acid from a reaction mixture obtained by a reaction catalyzed with a sulfonic acid-type cation exchange resin and containing the reaction product, the unreacted starting materials, the unwanted free sulfonic acid or sulfuric acid ascribable to the ion-exchange resin, and a reaction solvent if used, which comprises contacting the reaction mixture with hydrotalcite to transfer the unwanted free sulfonic acid or sulfuric acid into the hydrotalcite, separating the reaction mixture from which the free sulfonic acid or sulfuric acid has been removed, and recovering it.

2. The process of claim 1 wherein prior to contacting the reaction mixture with hydrotalcite, the unreacted starting materials and/or the reaction solvent is at least partly removed by stripping.

3. The process of claim 1 wherein the amount of the free sulfonic acid or sulfuric acid contained in the reaction mixture is 100 to 1,000 ppm.

4. The process of claim 1 wherein the reaction product is an aliphatic ether obtained by reacting an ethylenically unsaturated aliphatic hydrocarbon containing 2 to 22 carbon atoms with an aliphatic monohydric alcohol containing 1 to 32 carbon atoms.

5. The process of claim 1 wherein the reaction product is a glycol monoether obtained by reacting an ethylenically unsaturated aliphatic hydrocarbon containing 2 to 22 carbon atoms with an aliphatic glycol containing 1 to 32 carbon atoms.

6. The process of claim 1 wherein the reaction product is an aliphatic monohydric alcohol obtained by reacting an ethylenically unsaturated aliphatic hydrocarbon containing 2 to 22 carbon atoms with water.