Note: Descriptions are shown in the official language in which they were submitted.
¦ lOB12~;~
This invention relates to an improved process for
producing branched mono-olefines with 7 to 9 carbon atoms (C7-
C9 olefines) by polymerising à mixture of propylene and butene
over phos~horic acid-based catalystsO
It is Icnov~n technically to produce C7-C9 olefines
by the contact of propylene ~nd butenes with phosphoric acid
catalysts supported on ~.ilica, the operation bein~ carried out
at high tem~erature and pressureO
In par-ticular, in said known processes~the gaseou
reagents are fed to the top of a long vertical reactor and flow
through the catalyst arranged in the form of a fixed bed or
several fixed beds in succes~ion ~
The products leaving the bottom are then fraction
ated.
.The feed to the rea4tor may be either pure propy-
lene and butenes, or gaseou~ mixture9 containing propylene
¦ and bu-tenes originating from the thermal or catalytic cracking
¦ of suitable pe-troleum fractions or thermal reforming.
¦ The catalysts suitable for this purpose are known
20 ¦ technically and are prepared by impregnating Q silica or sili-
¦ ca-containing support with phosphoric acids, and then calcinin
¦ the support after impre~na-tion. The main problems enoountered .
¦ in the production of C7-C9 olefines are problems related to
the control of the progress of the strongly exothermic reactic n,
and problems deriving from the distribution of the reaction
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produc-ts.
In order to control the heat development, it is
usual to ~ilute the gaseous fced s-tream with non-reactive sub-
stances, ~er)erally hydrocarbons such as propene or butene.
'rhese cold non-reactive substances may be fed at on
or more points along the catalyst bed~ -
~ lternative~y, or in addition to this arrangement,
the reac-tor may be provided with suitable heat tran~fer surfac 8 ~ .
in order to extract the evolved heat, e.~. by using reactors
in the form of a tube bundle, or reactors provided with coils
or the like.
In spite of these arrangements, there is frequently
rapid de-activation of the catalyst due to the deposition of
tarry product~, and disintegration of the catalyst particles.
These phenome~a are considered to be at least partl ;;
a consequence of the formation oE "hot points" in the catalyst
bed, at which the reaction proceeds in an uncontrollable manne .
This variation in catalytic acti~ity in any case
creates considerable difficulty in the operation of industrial
plants.
~he polymerisation of propylene and buteness in ac-
cordance with the known art give~ olefine mixtures of a wide ;~
range of composition, generally from 6 to about 15 carbon atom . -
C6 olefines and olefines beyond C9 are used in the
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I`uel oector.
The C7-C9 rraction ia l~;ed as a raw material in the
~re~ ation Or oxo-a~cohols ~nd i. ~he most interesting fracti n
from the <~ ication a~.pec~.
There i9 thereI`ore a certain interest in improving
the yield of the C7-C~ olefine fr~ction at the expen~e of the
other reaction product,s" bearing in mind that when opera~ing
in accordance with the kno~m art, an average of 0.5-0.7 Kg of
C7-C9 oleIines are produce~ for each Kg of propylene and buten
es converted.
It is also of interest to provide a process which,
besides giving a high yield in C7-C9 olefines, al80 enables th
ratio of the constituents of said fraction to be varied over
a wide range in accordance with particular market requirements
In this respect, known-processQs are not sufficient
ly flexible to allow any particular olefine to prevail in the
production.
The disadvantages of the prior art are obviated ac-
l cording to the present invention by a proce~s for polymeri~ing
20 ¦ propylene and butenes in the homogeneous liquid pha~e whioh
on the one hand enables the formation of olefines beyond C9 to
be reduced or even eliminated, and on the other hand enables
the polymerisation to be controlled so that the formation of
¦ any one particular olefine in the range containing 7 to 9 carb
I atoms prevails.
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()~cralion ill the homo~eneou~ liquid phase considera~ _
ly reduce~ the (I~ ctiva-lion ~henomena ~eriving from the depo-
sition of t.~r on the ca-talyst and the ~ormation of hot points
in the catalyst bed. More particularly, the present invention
relates to a ~roce~s for ~reparing C7-C9 olefines from a mix-
ture of propylene and butenes over supported phosphoric acid
ca-~alysts, said process being characterised in tha-t :
~)a stream compri~ing propylene, butenes and recycle~olefine~
beyond C9 are fed to one end of an adiabiatic reaction zone
lo con-taining the catalyst (in this specification "adiabiatic
reaction zone" means a reaction zone wherein no substantial
heat transfer occurs); ~.
B) the operation is carried out in said zone at a tempera-ture
of 160 to 300C and under pressuré ~uch as to maintain the
. reagents and reaction products in the homogeneous liquid
phase, until at least 30~o but not more than 70% of the fed
¦ propylene andbutene~ has been converted;
¦(~)the reaction products are recovered at the other end of the~
I reaction zone~ and the unaltered propylene and butenes, the : `
20 ¦ C6 olefines.~ the C7-C9 fraction and the fraction beyond C9
¦ are separated; .
¦~D) the latter fraction is wholly or at lea9t partially recycled ,
to that end of the reaction zone to which the reagents are :
fed , and if required the unaltered propylene and butenes ar
fed to the same end. ~.
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¦ Thus one characteristic of the process according to
¦the presen~ inv~ntion is the ~olymerisa-tion of the propylene
and butenes in the ~lomogeneous li~uid ~hase (iOe. in the comp~ e
or substantially complete a~sence O:r the gaseous pha~e), the
homogeneou~ uid ~hase being guaranteed by recycling the
olefines ~eyond C9 which constitute one of the reaction ~roduc s.
Such a method of operation firstly leads to better
utilisation of the cata~yst by it being continuously wetted by
the liquid phase, with consequent removal of the tar which
0¦ would othe~lise deposit on its surface.
Furthermore, with the homogeneous liquid phase ther
is no formation of preferential paths in the catalyst bed, whi h
l are frequent in the case o~ a mixed liquid-gas phace and which
¦ create hot points and the uncontrollable development of the
polymerisation reaction It has al80 been found that the quan-
tity of olefines beyond C9 produced in the reaction i9 not onl
related to the degree of conversion of the fsd pr~pylene and
butenes but also depends on the presence of 9aid hea~y olefine
¦in the feed flow in the rsaction zone.
20 ¦ In other words, the net formation of olefines beyon
C9 is lower the lower the degree of conversion of the reagents
and the hig~er the quantity of heavy olefines fed together wit
the reagents.
¦ Thus in accordance with a further characteristic of
¦the process according to the invention, the ole~nes beyond C9
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are recycle(l ~o prevent their accumulation in the reaction
products, or ~t leas-t -to control said accumulation within a
required range of values.
It has also been found that the amount of the recy~
stream, or rather the rat;o ~f the recycle stream to the fed
~ropylene and ~)utenes influences the distribution of the'C7-C9
ol~fines. 'l'hus in accordance with a further characteristic of
the process according to the present invention, the yield may
be modified towards one or the other of the olefines by simply
varyin~ the parameters~ including said ratio.
In the description given hqreinafter,
- C6 olefines signify those reaction product~ which boil at 20
to 80C;
- C7-C9 olefines signify tho6e which boil at over 80C and up
to 145C;
~- olefines beyond C9 signify those which ~oil beyond 145C.
Furthermore, in the C7-C9 olefine range :
¦- hepteness signify those products whioh boil over 80C and up
I to 100C;
20 ¦- octenes are those which boil at`over 100C and up to 125C;
¦- nonenes are those which boil at over 125C and up to 145C. ;~
Thus in the process according to the present inven-
tion, a stream containing propylene, butenes and recycle olefi
nes beyond C9 is fed to one end of a reaction zone containing
the phosphoric acid-based ~upported catalyst~
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The cnt~lysts useful for this pur~ose are tho~e
known catalysts ~repa.recl by mti xing E~hosphoric Qcids with a sili
ceous supl)ort and thell subjecting the impregnated support to
heat treatmen~.
SupE~or~;s sllitabie :~or the purpo~e are silica~ and
preferabl~ dia-tomite con-taining more than about 8~o by weight
of si] ica. .
The phosphoric acids which may be used include orthc _
phosphoric, metaphosphoric and/or pyrophosphoric acid, and gen
erally acids in which the valency of the phsophorus is 5.
The best results are obtained by those phosphoric
acids with a high P205/H20 ratio, for example the product know~
as poIyphosphoric acid, the P205 content of which is about 85
by weight. ~
The catalyst is prepared in the ueual manner by re-
¦ducing the impregnated support to granules, followed bg drging
¦and c~lcining- This latter operation i8 usually conducted at a
temperature of 200 to 90~C and preferably 250 to 600C, gen-
erally by graduallg rai~ing the temperaturo to the chosen valu
In all cases, the catalgs~s preferred for the prese t
invention are those which contain in the orde~ of 65% by weigh
of phosphorus expressed as P205.
Said catalgsts are disposed in the form of a fixed
bed in the polymerisation reactor, and the feed stream is fed
to the head, or preferably to the foot of the reactor.
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In sai~ strcam, ~he weight ratio of the propylene t
butenes may vary be-twe~n wid~ limits such as 0.3/1 to 3/1, the
~referred value being of the order of 1/1.
The term butenes signifies isobutene, butene-1,
butene-2 or mixl;ures thercof.
Generally use i~ made of the already mentioned ole-
fine fractions ori~inatin~ fr~m petroleum refining operations,
which contain all the aforementioned constituents. r
In this case the mixture fed to reactor also conta~
10 hydrocarbons which are inert under the conditions of operation
these being essentially propene and butanes.
As a special characteristic of the invention is to
only partially convert the propylene and butenes in each pas-
sage and then recycle the uncon~erted part after partial purg-
ing, usually the operat~n i8 carried out with the weight ratio
of said saturated hydrocarbons to the propylene and butene~ of
¦less than 5/1, and generally of the order o~ 1/1.
¦ The quantity of olefines beyond C9 ~or~recyQle must
¦be at ieast equal to the qu~ntity required to guarantee the
20 ¦ homogeneous liquid phase under polymerisation condibions.
¦ Thus the minimum weight ratio o~ 9aid recycle strea n
¦ to the propylene~and butenes is of the order of 2/1 to 3/1O
¦ If the amount of saturated hydrocarbons present is
high, then the value of this latter ratio i8 proportionally
increased.
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~ h~r valu~s of said ratio are used when operating
¦at higher l;empera-ture or~ lo~ler~ ~ressure, bearin~ in mind the
need -to maintain a ]1omo~neous liquid phase under ~action con-
ditions.
Ir a sma1J. increase in temperature bet~reen the inle-
~d outlet of the reacti.on zol~e i9 requ~d for the same degree
of conversion of the reagents, the ratio of ole~nes beyond C9
to the ~ropy~ene and b1ltenes should be high.
¦ 'l'he maximum value of this ratio depends on economi-
lO¦ cal considerations.
It has also been found desirable for ~later to be
present in the feed stream to the reactor, normally its quanti-
Ity being maintained at around 500-2000 ppm~
¦ The polymerisation temperature may vary over a wide
. ¦range such as 160 to 300C, preferably 180 to 250C.
I The pressure used for this purpose may vary over a
¦wide range such as 10 to 60 K ~ cm , the particular value de-
¦pending upon the composition of the feed stream and other ope-
¦rational condition3, so as to guarantee the homogeneous liquid
20 ¦phase in the reaction zone.
¦ Thus typically with a weight ratio of reagents and ..
¦ possible inerts to ole~ines beyond C9 of the order of 0.33/1
and a polymerisation temperature of 200-250C, the pressure
used to maintain the homogeneous liquid phase is arcund 40 k
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~` I~ is also converlier1t to pre-heat the feed s-tream
to the re~ctor to a l.em~eratu~e of 160 -to 240Co
The re.~ction does no-t begin below 16~C, while abov
240C the cxothermic na.ture of tlle reaction means that the
tem~erature reachcd is such as to cause rapid deactivation of
the catalyst. According to the present invention, -the propylen
and butenes are only ~artially converted, and generally this . :
conversion may vary from 30 to 70%, the ~re~erred value being
of the order of 50~0~ The conversion may be influenced by choic
of tem~erature, by adjusting the residence time under polymeri
sation conditions and by varying the ratio of olefines beyond .~ :-
C9 to the propylene and butenes, bearing in mind that the reac ~ .
tion velocity is-reduced by a higher dilution of the reagents. : :~
Given the temperature of the operation, said resi-
dence time may vary from 10 to 60 minutes, ca~ated as the :~
ratio of the catalyst volume to the feed volume per minute,
¦said feed being considered liquid at ambient temperatureP ~.
¦ In a preferred embodiment of the process accordlng
~to the present invention, a number of separate adiabatic cata- :.
20 ¦lyst beds are used dispo~ed in series, feeding the whole of ~:
¦the propylene and butene reagents to the firot bed together
with the olefines beyond C9 in the ratio previously indicated.
A further quantity o~ olefines beyond C9 is general
ly fed at ambient temperature between each pair of adjacent :
beds in order to control the exothermic extent of the reaction
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.~ 'I`he number of catalyst heds may vary f`ro~ 2 to 10~
~referab].y :I`rom 3 to 5, ~nd i~ each case said number depends or
t~le maximum temperature difference to be maintained be-tween th~
outlet and inlet stre.Lm for each individual bed.
Conveniently ~his tempera-ture difference is 1 to
7~C, pre:rerab~y 5 to 25C.
Under these conditions the purpose of the olefines
beyond C9 recyclcd be-t~/een one stage and another is to cool th~
reaction mixture leaving each catalyst bed, this cooling conve- .
lo niently proceeding to a temperature equal or approximately equ a
to the inlet temperature to the catalyst bed.
It is evidently possible to control the temperaturl ,
and ~uantity of the olefines beyond C9 between adjacent stages
so as to obtain the required temperature profile at each indi- .
. vidual stage, .
The mixture leaving the polymerisation reactor? or
leaving the last catalyst bed in the case of a number of reac- .
tion stages~ contains unconverted propylene and butenes and .
possibly inert saturated hydrocarbons, in addition to C9-C15 ~.
branch olefines. ~he mixture i8 fed to a distillation section
where the followin~ are separated out :
- propylene and butenes, and any propane and butanes, whioh
are genera.lly recycled after purging to prevent accumulation
of inerts;
- the C6 fraction, used in petrol;
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- tlle (~7-c~3 ~r.lction ~ ich i5 co.Llected ~nd used or the produc
~1,ion Or oxo-alco~lol~ `
- the i'racl;ion beyond C~, wlllch i~ wholly or partially recycle .
~s previouslvr stated, the extent of this recycling
1i.5 col~1;rol~d in rel~.ti~n ~vo the ~rovi~ion of a homo~eneous li
¦quid nl1ase (luring ~olvvmerisation~ the degree of accumulation o
¦o~eiine~ b~yond C9 and the amount of cooling o~ the reaction
l mixture wh~n U~i11g a nllmhCr 0~ catalyst beds in series. "'~
¦ ~y means of the process according to the present ~ ;
lO ¦ inven~ion, it is possible to influence the reaction towards th
prevalent formation of a specific olefine in the range C7 to C
For this purpose~ the polymerisation temperature,
the conversion undergone by the propylene and butene~ during
each passage and the ratio of these reagents may be varied in
addition to the ratio of the olefines beyond C9 to the propyle e
and butenes. `
¦ Thus, other conditions boing equal, a lower rea~en
¦con~ersion favours -the'forma~ion of C7 olefines, w~ile a highe
¦propylene/butene ratio favours a higher C9 olefine yield.
20 ¦ ~inally, a higher polymerisation temperature, othe
conditions being equal~ favour9 bhe form~tion of C7 olefines.
In all cases reaction products are obtained with a
¦mono-olefine content exceeding 98% (ASTM D~13-19), and said
lolefines are particularly suitable for the production of oxo-
¦ alcohols.
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l.xam~ ~ e 1
~ hre~ liabia~ic ~eactors are used in series con-
tainillg a lotal o~`'l() 1~ (a~roximately 72 litres) of the cata
lyc~,t in the form of a fi.xed bed.
The catalyst consists of phosphoric acids mainly
supported on dia-tomite, and has a P205 content of 65/~o by weigh .
2051~g/hour of a liquid mix-ture preheated to 200C
is fed to the bottom of the first reactor, c~nd has the follo~n
average compositioll :
lo propylene 6~25% by weight
butenes 6.25~ by weight
propane and butenes12.50~o by weight
olefines beyond C9 75000~0 by weigh~ .
The feed stream also contain~ a quantity of water .
equivalent to the saturation vQlue ~t ambient temperature.
The reaction products disoharged from the top of
each reactor are fed to the bottom of the next reactor after ~`
adding 18.5 Kg/hour of olefines beyond C9 between the first an
~econd reactor and 13.3 K ~ hour of olefinee beyond C9 between
the second and third reactorO
The olefine hydrocarbon~ containing ~ and 4 carbon
atoms fed to the first reactor form the fre~h portion (60%) of
the feed, with the remainder being the recycle from the distil ~ :
lation section.
The olefines beyond C9 fed to the three reactors
are the recycle olefines from said distillation section~ ~ :
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¦ Irl the l`irst reactor the ol~erating ~ressure is ap-
nroxima-tel y ~ g/cm , and the products discharged from the to
at a temI)crature of` 215C are c~ed to 200C by the strec~m of
¦ olefines ~e~ond C9~ and are then fed to the bottom of the sec~ ~ .
rcactor~ ~¦~
In ~.he necond rea.~tor, the operc~tin~ pressure i8
a.~proximal,e].y ~0 l~g/~ , and 1;hc ~roducts discharged from the
to~ a~t a t,emperature ol` 210C are cooled to 200C by injecting
¦ olefines beyo1ld C9, cmd are then fed to the bottom of the thir
lO ¦ reactor.
In the third reactor, the operating pressure is
about 39 ICg/cm and the overall conversion of the propylene
~nd butenes in the three reactors is in the order of 45.C~o,
¦ The products di~charged from the top of the third
¦ reactor at a temperature of 205C are fed to a column operati~
at 10 Kg/cm2 where approximately 40 ~ hour of a hydrocarbon
mixture containing unaltered propylene and butenes plu8 propan l ~
¦ and butanes separates from ths top. ~ .
l Th~ mixture i~ recycled to the first catalyst bed
20 ¦ after partially purging.in order to maintain the concentration
of saturated hydrocarbons constant.
l Approximately 197 K ~ hour of an olefine mixture
¦ are recovered from the bottom of the column, the mixture havin t
¦ the ~ollowing a~erage com~osition :
¦ C6 fraction 12. ~ by weight
C7 fraction 41.5% by weight
C8 fraction 16.5~ b~ weight
C9 fraction 27~o by weight .,.
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rraetioIl beyol1d C9 3~ ~ by wei~ht
Tlle mixture is di.~ti~led to separate the C6 fractio
(1.3~ KgJhour), the C'1 .f`racl;ion (4.79 K~/hour)~ the C~ fraction
(1.50 ICg/hour) and tIle C9 fraction (1.11 ~C~ hour).
'rhe residue f~om said distillation (approximately
197 K~/hour) i5 almo~t totally recycled, and the net productior
of olefines beyond C9 is approximately 0.35 ~g/hour.
I~am~l.es 2-
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The operation is carried out in a like manner to : :
example 1, but varyin~ the composition of the feed stream to
the first reactor and/or the degree of overall conversion of .:
the propylene and butenes. Furthermore, in examples 4,5 and 6,
. the temperature of the streams entering the reactors is 220C
. instead of 200 as in the other c~es. ~he result~ of the9e ..
exam~les are shown in table 1.
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