METHODE DE RECUPERATION DU BUTENE-1 DE QUALITE POLYMERISATION

PROCESS FOR THE RECOVERY OF POLYMERIZATION GRADE BUTENE-1

Abrégé anglais

CASE 1803
"PROCESS FOR THE RECOVERY OF POLYMERIZATION GRADE BUT-
ENE-1"
Abstract of the disclosure
Polymerizaiton grade butene-1 is recovered from a
C4 stream containing butene-1, isobutane, isobutene, n-
butane, buteanes-2 and reduced amounts of C3 and C5 hydro-
carbons, butadiene and acetylenic hydrocarbons, by sub-
mitting the stream to the following stages: etherifying
with an aliphatic alcohol to the purpose of eliminating
the isobutene, which is transformed into the alkyl-tert-
butyl ether corresponding to the alcohol used, separa-
tion of the tertiary ether thus formed from the remain-
ing of the stream, separation by means of distillation
of the isobutane, separation from the residual stream,
by distillation, of butene-1 at a purity level of from
80% to 95%, selective hydrogenation of the butadiene and
of the acetylenic derivatives contained in the said stream
of butene-1 at the said purity level, distillation of
the hydrogenated stream with separation of polymerization
grade butene-1.

Revendications

CASE 1803
Claim
1. Process for the recovery of polymerization grade
butene-1 from a C4 fractionwhich contains it, free from
isobutene or substantially free from isobutene, compris
ing the stages of to distill in a first distillation
column, at a pressure comprised in the range form 5 to
20 abs. atm., such fraction, obtaining a top stream es-
sentially containing isobutane and a bottom stream con-
taining the residual components, and of the distill the
stream containing the residual components, in a second
distillation column, at a pressure comprised in the ran
ge from 3 to 10 abs. atm., obtaining a top stream of but
ene-1 at a purity level of from 80 to 95% and a bottom
stream comprising the high boiling compounds, n-butane
and butenes-2 cis- and trans-, characterized in that the
top stream from the second distillation column is fed to
a selective hydrogenation unit of the butadiene and the
acetylenic derivatives, such compounds being reduced to
a concentration comprised within the range from 30 to
200 ppm, the stream originating from the selective hydro
genation unit being finally fed to a distillation column,
operated at a pressure comprised within the range form 3
to 10 abs. atm., obtaining from a plate close to the top
of the column, polymerization grade butene-1.

Description

~Z3~
CASE _1803
~ he present invention relate~ to a proce~s for the
recovery ~ po3.ymerization ~rade butene~1.
l'he butene-1 is contained in the C~ h~drocarbo~
strea~ns consisting of ~arlable percentages o~ the ~ol
5 lowin~ co~ponent~: butene-1, isobutane1 i~obuteneg n~
bu~ane, butenes-29 C3 and ~5 hydrocarbons both ~aturated
. and o~ ole~inic charaeter, butadiene; ace-tylenic deriv-
; ati~es.
~he ~4 hydrocarbon stxeam~ to be llsed as the raw
materi~l~ according to the present in~entio~ ha~e a low
~ontent o.~ bu~adiene and acetylenic derivative39 qo if
the starting batch is originating from steam cracking
proce~e~9 the bu~adiene co~tained the~ei~ r~e per
oerltages has to be remo~ed by mean~ of a solvent or an~
other process.
; ~he compo~ition o~ the C4 hydrocarbon ~treams tv ~e
u~ed aocording to the present inve~tion i~ c~mpri~ed
within the ~ollowin~ ranges:
3 0~2 1~5 % by weight
~0 i-C 1 - 30 ~ ~y weight
: i-C4- 10 - 60 % by ~eight
^ n-C 3 - 20 ~ by wei~ht
C4- 10 - 40 % b~ welght
?-~4- 8 - 30 ~ by T~eight
C5 0.1 - 1,0 % by weight
Butadie~e ~ A¢etyle~ic0~1 - 6 ~ ~y weight
The problem to be fa¢ed is the r~o~ery o~ the but-
e~e-1 keeping a~ low a~ po~sible the tran~orm~tion o~
ute~e-1 into butene-2 in the stage of t~e selective
hydrogenation of the butadie~e and the ~cetylenlc de~
::
.

9~g
ri~ati~es 0
The art kno~ln te~ches that the selecti~e hydrogena
tlon ~l the butadiene axld the acetylenlc hydrocarbon~
ha~3 to be eîfected before the sepa~ation stage~ o~ the
5 variou~ components from the butene-1, but ~ en opera t-
ing by means o~ the l~nown F~rt proce~ses~ to~ether ~ith
the hydrogenation al,~o a noticeable isomeriz~tion Ot~C~
o:E the buterle-1 to b~tene-2.
~he rate of ~uch isomeriza tion depends orl the quan-
ti ~ o:~ butadiene allo~ved by the speci:~icat-loll~ oï but
ene-1~ The lnwer i~ the ma~imum content of butadiene al~
lowed b~r the ~peci~ication.Y of butene-1, the lower must;
be the quantity of the re~idual butadiene in the ~4 stream
a~ter ~he h~drogenation~ snd the higher the lo~ o~ but~
ene~1 becau~3e of the iso~erization to butene~2.
~or purely indicative rea~ons, ~tarting ~rom a con
tent of butadiene in the stream to be fed to the hydro-
genation ~tage OI about 2%, if the maxi.mum allo~ved con-
tent of butadiene in the ~pecifications for b!lter~e-1 is
: 20 200 ppm, the lo~ o~ bute~e-1 because o~ the isomeriza-
tion iA about of 2~ ~y wei~ht, if the butene-1 specifica
~ tion allow~ a ~aximum content o~ 50 ppm o~ butadiene,
: ~ the iso~erizatlon lo~s o~ bute~e-1 i~ hi~her than 5% by
~eightO
It has now been surpri~i~gly found that i~ i~ po~-
ible to reduce the disadvantages o~ the tech~iq~e ~rom
~; the prior art, ~y resorting to a selective hydrogenation
stage o~ the butadiene and acetylenic derivstives, po~-
~ : itio~ed in a suitable point of the plant.
: ~ 30 ~he a4 stream i~ ~ubmitted to the oonventional trea~
men~s for ~he ~eparætion of isobut~n~ by mean~ of tr~n~ :~
'''
~;
. ~ .: . . ,
:: : ~ ''' ' : ,.

;~2329~
~ox~i.n~ it into an ~ yl--tert.~bu-tyl ether by reaction
. with an ali.pha-kic alcohol~ pre~erably methanol~ i~ the
presence o~ ~ heterogeneou~ catalyst ~;th ~unctional
sulphonic ~roups on a styrene~divynilberlzene matrix~ in
; 5 particular o~ the ~mberly~t 15 type~ ,
By mea~s o~ the reacti.ons de~cri~ed, p.ractical~y all
the i~o~utene i~ ~.rans~ormed i~to an alkyl-tert~bu-tyl
ether~ wh~cl~ turn removed by di~tillatio~ in a
l~rlow~ ~anner.
The process according to the present invsntion com
pri.s~s the stages o~ to di~till in a ~ir~t disti.llati.on
column operated at a pressure in the .ra~ge ~.rom 5 to 20
- abs. atm,, the Cq ~rac-tion~ containin~ the previou~ly
~et forth cornponexlt~;, fx ee f`.rom isobu tene or sub~tant~
l~r f~ee :~rom i~obutene$ ohtaining a ~op rtream consi~t~
ing e~sentially OI isobutane1 and a bo ttom ~tream con~
~i~ting o~ the residual compone2~ts9 whioh i~ in turn di~:
:~ ~ tilled in a second dis tillation column ~t a pre~ure
compri~ed between 3 and 10 E3bs . atm~, obtaixling a top
~tream con~isting of butene~1 at R purity level wi~hi~
the range from 80% to ~5% (contai~ing butene-1 plu~ fun
damentally butane and butadiene ~ acetylenic deriPatives )
~: and a bottom stream containing high boilin~ oômpound~, n-butane ~nd t~iY- and tran~- butene-~.
~he top ~tream from the seoond distill~tion colu~
Eed to ~ ~elective hydrogenation u2~it of the butadi-
ene and the acetylenic derivati.~es" the ooncentra~ion of
~aid compounds being redueed to ~ Yalue within the r~nge
Xro~ 30 to 200 ppm ~n order to fulfi.lling the speci~i-
;: ~ 30 c~ions for the polymeri%ation ~rade butene-1 .
q`he hydroæexlati~g unit i~ operated under the Iol-
:,:
.
~:
:~, .

~'~3~ 9
~ o
lowi~ oondi.tion~: in:l et tempe~ature 35 to 50G9 opexat
irlg p:res~ure ~ to 20 Qbs o a t~n~
'~he .stx eam o~i~irl~ tin3 ~rom the selectlYe hydrogexla
tion unit;7 dep;rived o:~ the die~io a~ld ace~ylenic corr
pol~.nd~3~ is f:ed to a distillat:Lon coluu!~ oper~ted at~ ~
p:re~sure within the ran~e :Erom 3 -to 10 ab~ 4 ~tm.,, obtain
in~ f'rom a plate close to the top o;~ the coll~rr~ pol~mer
izatio~ grade bu-texle 1 and as -the bot tom strcam, .n~but;-
ane and butenes~27 with reduced amountæ o:f butene-10
~he proae~ acoording to the present inventio~ m~Ln
tains its ~.dvanta~es o~ requirin qui-tc ~oft reac-tion
condi~ion~ al~o in the ca~e that the select:ive hy-lrogen,E,~
: tio~ ~le e~fected in the presen~e o~ ~nhibitors o~ -the
l~o~erization o-f bond ~rom butene 1 to bu~ene-2 to be
added to the batch C4.
'urthexnlnre the procesa accordin~ to the pre~ent
i~vention has in any cases the additional adva~tatre of
: Rllo~in~ the dlmensions to be xeduced o~ ~he e~uipme~
required by the seleoti~e h~drogenation a~d a~ ~ cons
:~ 20 quence of the investment capital~ -
As ~or the types of the component~ o~ the ~riou~
stream~ referenc~ shall be made to the followjl~g ~a~ple,
hich h~s not to be i~tended a~ limltative o~ the ~.nYen
ion i~ regard to the concentratlol~ o~ the variou~ oom
pone~t~ in a~y ~in~le ~tre~m and to the operational pres
sure~ o~ the various stage3.
E:~:ample
'I'he :Example has ~een performed according to the
s~hematic iI~ trat1 on of the attached drawir~g~ which i~
: . 30 not Iimi ta~ive of the inven t;ion 9 irl whieh ( 1~ is the C4
: :
trearQ çomprisi.ngS a~nong other~ butene-l, isobute~e,
: : : .
: ~ .

hutadiexle anc~s acetyle~ic deriv~tive~7 (2) i9 a E~trealn
o:E me~h~rso3. beillg f'-ld to the etheri:Eyin~ unit ~1~) o:~
the lsobutene9 (3) i~ the strea.m o:f methyl~tert~but
e tklex~ produ-~ed ~ ( 4 ) ics the ~ eam sub,~tantia1 ly ~ree
:Erom iSObll~erle9 (18) is the ~ir,~3t dlsti:Llatiorl co~.um~
opexa ~ed a t about 14 abs . at~Q~ ~ ( 5 ) i.~ ~he top s tr~eS~n
esserltially coSnpri~3:~xlg isobutane9 (~) ic~ ~he re~idual
stream which i,s ~ed to -the ~econd di~f-3t11la~ion colllm
(19) opexated at ~ pressure of` about 6 ~bs~ atmO~ (7)
i,9 e ~txeam eonta-Lning e~s~tially bu-te1ne~1~ (8j ls a
~JG~eam cont~irlin~ tkle heavy produc ts; t'rle s tr eam (7 ) l~
:fed -to the hydrogenati.on unit (17) to whi.ch hydxo~en i8
fed by the line (9), and from which the s-tream ~11 ) iB
discharged ~ essentlal.ly eonsi ~Iting o:~ i;he excess hydro-
~gen ~ld b~tene-1; (10) iæ the hydro~enated ~tream which
i0 fed to the fractionatiorl column ~20) operated a~
pressure o:F abou-t 7 abs. atmO ~ from the top o:E which ~
~liream ( 12 ) i ob tai~ed 9 con~isting of u~ o~den,s~ble mat
ter and butelle~ rom ~he ~enth plate ~.rom the top ~L
~0 ~treRm ~13 ) bein~; obtnined oi~ po:l.ymeriz~tion ~rade but-
ene-1, and f'rom the bottom the reæidue (14) being obtained,
sub3tantial.1y con~isting of n~ tane arld bu l;e~e~2 0
~he stream ( 1 5 ) iB the sum Q:~ the stl~eam~ ~ 5 ), (8 3
a~ d ~ 1 4 ) .
The balance o:l~ the matter~ o~ the proce~ is shown
~n the followin,~ Table, where the position number~ are
ref erred to the drawing .
~,

~2329~L~
o
o
o
a) ~
~ .
~: III,,,,,,
o
3 ~ ~ 0 !n
O I O ~G ~ I O
CO '~-
s
~ l l l l ~ l 0 c~ ~ l ~
bO I I I I I ID N t` I ~S\
0 0
0 ~ - O
3 l l o o ~ ~ m o bD I 8 .
~ a) c ~'
s
W, ~ ~ o~oLn ~ ~ ~
. ~ 0 a) ~ ~ 0 o
3 1 ~ 0 0 ~ o ~ \~ I o
I IN ~) 0 ~ O ~ ~J I a )
W I I O ~D N 0 ~` I O
~ t` t` ~ 0 0
~" ~ ~ , ~ 1 o
~ ~ ~ ~ O O O O l O
CO C ~1 1 0
~S~
S I 0 0 .-1 t`ID O ~ ~) ~1
00 ~ ~ CO
,
I O ~ O ~ o ~ I i O
N ~) ~1 ~ O
S I o,, ~ ;o~ o~
O t`'J 0 ~
3 l o ~ ~\i o ot~ ~ 0r~ O
: ` : ~ ~ ~ ~ ~ O
O O O O O O OO o O
S
D ~J C
C O C C T-- ~ ~3 Q) O ~ ,
o s~ ~ ~ I ~ c m ~ s~
~ 3 3 C m 3 ~ m
u~ O O J~ ~ m ~
~: :

~'~32~L9
~I 11 ~ ~1 LS~ L-- ~1 CO O
G ~ ~ f
11 ~ ~ O ~ ~ ~
~ I 'h ! 11 0 co ~ O ~n cn c~
11 11
. ' . . I 1
E: I 11 11 11 11 Il .. o
I 11 11 11 11 IJ 11 ~_ ,
t~ I 11 11 11 ~ 11 0 11 ~ CO 11 0
I b~ I1~ 11 11 11 11 11 . ,
I.~d 1
ll ll ll ll ll ll
t 11 11 t- ~ O ~ ~t~ 11 11 <~
11 11 o o cn P~ C~o 11 11 o
` I il 11 ~ O 11 11 0
;: ~ I ~ I 1l 1l 1l n1l
.~ ~ I ~ I o11 11 11 o ~ 1111 11o
: ~ ~ I U U 11 11 11 1111 11~
: ~ ~ t~g~~ ~1 11 11a:) 11 11 ~IO
n 1l 1l 1l u 1~
~ 1 11 11 1l 11
t ~ U 1l 1l 1l 1l U
O U O
l H
. I ~ n o c~ l o
O ~ I h : I - 11t!J ~ N n ~ Nc~ il ~; ..
~ I U ~ U '~ UCS~
. D a O ~ o
O ~: a I ~i J, O
rl ~ ~ D O i ~ S~I ~ ¢
o o ~ t~)a~ t~; ~ E~
V H H 3 ~ s . ~ v ~, ~
~, 7~ : ~