Note: Descriptions are shown in the official language in which they were submitted.
2~
~he pre~nt invention relates to a proce~3 for th~ produotion
o~ arom~ti~ hydro~arbon~.
It has been known to use iq~ynthetic ~aolites and/or aluminas
as catalysts in the production of aromat~c hydrooarbon~ from open
chain hydrocarbons. Howe~er, the life of these catalysts have
been ~hort and th~ yield and selectivity of the cyclised products
'~ ha~e been unsQtiisfactory due to severity o~ the reaction conditiono
:i
needed to carry out the reaction.
It has now been ~ound that by choosi~g a suitable metal as
catalyst the activity over conventional ratalysts may be increased
significsntly and acceptable yields of the aromatic h~drocarbono may
be obtained under relatively mo-lerate conditions.
Accordingly, tha present inventionis a process for producing
,1
3 aromatio hydrocarboni~ comprisin~ aromati~ln~ an un~aturated hydrooarbon
; containing at least six carbon atoms in ths preqence of a catalyst
composiition comprising elemental gallium or a compound ~ gallium
deposited on a support.
~i ~he unsaturated hydrccarbons of the present invention may be
l selected from one or more straight or branched chain isomers of
hydrocarbons containing between 6 and 16 hydrocarbons. Methyl
'1~ .
pentenes, dimethyl pentenes, trimethyl pentenes, hex~nes, heptenes
~, and octenes sre preferred.
i Preferred examples of gallium compounds are gallium o~ide,
l~ gallium sulphate and gallium ions exchanged by the ~urface
,~ hydroxyls of a surface active oside such as hydrated silica or1 ,
l~ hydrated alumina.
`, ~he amount of gallium present in such catalyst composition~
may vary between 0~01~o and 1~,', preferably between 0.1 and 6~o
.J by weight of the total support in the catalyst composition.
t 3 Suitable axamplesi of support for the giallium/gallium compound
1 ,
, _ 2 - ~ `
.
:~ .
::''.l
c~taly~ts of the pr~s~nt in~0ntion includa alumina~ such a~
eta-alumina~ gamma-alumina and boehmite; ~lumin~ and silioA
with or without ~urface hydro~yl groups which may be agchanged
by ion~ of metals selected from gallium~ alwminium, iron and/or
~ nickel; activat~d carbon; and refractory gallium o~ide. Silica
;~ ~ support~ especially those ~ exchanged 3urface hydro~yl
groups are preferred.
The catalyst ~ 9 prepared by impr~gnating the ~upport with an
a~ueou~ solution of a soluble ~llium compound, e.g. gallium
nitrate, The paqte BO formed may be evaporated to dryness under
vacuum and then pyrolysed at elevated temperature in a ~tream of
;` air. Where it i~ desirable to use surface active qilica or alumina
a~ support, the hydro~yl groups may be exchanged by gallium ions.
The catalyst composition o~ the present in~ention may also
contain other metal~ such as nickel, cobalt, iron, manganese, thallium,
;
; palladium, platinum, indium, germanium~ chromium, tin and/or zinc
in small quantitie~ to improve the activity thereof. Nickel and
nickel compounds are preferred,
The cataly~t ~o prepared may be formed as a fixed bed and
`~ 20 activated in tho reactor tube itself. The activation may be
carried out by purging the catalyst with a ~uitable gas such as
nitrogen or alr at the proposea reactio~ temper~ture.
, :/,
he unsaturated hydrocarbon is thereafter aromatis~d by pa3sing
-1l over the catalyst at a temperature between 400 and 75DC
~ preferably bet~een 500 and 600C. The reaction i9 preferably
,.~ . .
carried out in an inert atmo~phere. By "inert atmosphere~ is
meant a ga9 ~hich is inert under the reaction conditions such as
~i hydrogen or nitrogen.
The arom~sation reaction is suitably carried out under pre~sure
~, 30 ranging from 1 to 20 atl~ospheres, pre~erably from 1 to 5 atmospheres.
, ~ .
: .:
`i - 3 -
.
~:,
''' ' .
~.
. ~
The products of the reaction which are mainly aromatic hydrooarbons
are then identified and isolAted. U~FIaturat~d C8 hydrocarbon3
may be con~erted to xylenes by this process~
'rhe unsAturated hydrocarbon being aro~t~d may be produced by
the dimeri.sation of a lower olefin, For example3 the C6-C16
, unsaturated hydrocarbons to be a~omat~d may be ~epared by the
: dimerisation of a C3-C~ mono olefin.
The dimerisation is suitably carried out ovêr the ~ame catalyst
, . as that used for the cyclisation reaction, i~e. elemantal gallium
or a gallium compound deposited on a su~port.
The dimerisati.on is 3uitably carried out by passing the mono
o2
A olefin hydrocarbon over the catalyst at a temperature between_~
; and 300 C, preferably between 50 and 250 C. The reaction is
preferably carried out in an atmosphere inert under ths reaction
~' conditions 3uch as hydrogen or nitrogen.
,^~ The dimerisation of the mono olefin is suitably carried out
,':, at a reacti.on pressure ranging from atmospheric to 130 atmo~pheres,
';, preferably between ~ atmo3pheres and 100 atmospheres,
The produots of the dimerisation reaction ruay, without
, 20 i~olatlon, be directly sub,jected to the aromatie~tion reaction as
. .
~ before to obtain the aromatic product90
; .~,
''.j~'`'!;: The mono olefinic hydrocarbons containing 3 to 8 carbon atoms
,.'1 mny in turn be produoed by the dehydrogenation of the corre~ponding :~
:: saturated hydrocarbons.
'rhe dehydrogenation of the saturated hydrocarbon to the
corre~ponding olefin may be carried out by passing the 3aturated
~ hydrocarbon over the same cata].y~t as used for dimerising the olefin
`~ and for the ~xmatis~ of the unsaturated dimer thua produced.
', ':~i
'rhat is, the dehydrogenation may be carried out using a catalyst
comprising elemental gallium or a compound of gallium deposited
~s,:
:: ~^;,: ' '
~ 4 -
: i
... .
-
on a support. '~rhe types and composit~ons o~ the cataly~t~ are th~
: same ~ used beforr~ for th~ other reactions.
The saturated hydrooarbon is suitably pa~Red o~er the g~lliu~
catalyst at ~ temperature of between 400 and 750C, pr0ferably
between 5~)0 and 600C, to form the mono olefin.
At the lower end of the saturated hydrocarbon feedstock range
higher temperatures may be required for the dehydrogen~tion step a~d
conversely, as the number of carbon atoms in the feed incrsases,
relatively lower temperatures within the specified rangs ma~ be
used to obtain optimuln yields.
`~ The dehydrogenation step is suitably carried at a reaction
.~.
pressure of between 1 and 20 atmo~pheres, preferably between 1 ~d
~` 5 atmospheres.
The dehydrogenation is also preferably carried out in an
atmosphere inert under the reactions conditions, such i.i3 hydrogen.
, ,.~ ,
The hydrogen may be that liberated 'in situ' durine the
dehydrogenation reaotion. The mono olefinic products may then be
identified and isolated. 'rhis method may be used for producing
~. ,,
~-' propylenes from propane, butenes from n- and iso-butanes, pentenes
:, 20 from pentanes and ~o forth.
;i The dehydrogenated prorluct mayl without i~ol-tion, be directly
~1 dimerised and aromat~din one step to an aro~atio compou~d, For
exa~ple, propane may be dehydrogenated to propylene ~hich ~ay then
be dimerised and anD~tisedin one step to benzen~. Simi~arly,
.:~
isobutane may be dehydrogenated to isobutene which can be dimerised
and ar~E~d to xvlenes.
The dehydrogenation, dimerisation and aIo~atlsatlon raacti~ns
may proceed si"lultan~ously and the product mix may be controlled
by careful control of reaction conditions. q'hat is, for a given
feedstock, the dehydrogenation normally proceeds at the lower end
- 5 -
: . ~
.. ~ '.
of th~ ~peci~ie~ temp~ratur~ ranga wherea~ tha dehydrocyclo-
- dlmeri3at,ion reaction to th~ correspondin~, aromatic hydrocarbon
'- predominlltes at the upper end of the ~am0 temperature ranga.
'rhe principal adv:~tage of the present proces~ iB that the
~tep~ of th0 dehydrogenation, dimerisation und ~roms~tl~a can all
be carri,ed out using th~ ~ame cataly~t. That i~, the Jaturated
hydrocarbon can be con~erted to the arom~t~ product u~ing ~ ~ingle
qet of reaction condition~ over a single catalyst. Furthermore,
one can start with a mixed feed containing both 3aturated and
~ 10 unsaturated hydrocarbon~ and convert th~ ~ixture into the desired
',', ar ~ic product in a 3ingle step. Thu~, a ~4 ~eed~tock
' containing one or more of butanes~ butenes and butadi~nes may
be converted into'xylene~ in a single reactor without isolating
the intermediate~.
., , ~ .
,'~ The invention i9 further illustrated with reference to the ,,
accompanying example90
tion ~f ~ C-~ ~/Eta-alumina cataly~t
~ To a~qolution of 10 g gallium nitrate (Ga(N03]308H20) in
``~ 20 approximately 30 ml o~ distilled water~ 26,6 g eta-alumina was
'1 added and stirred into a paste. ~he paste was evaporated to dryness
in a va~uum oven overnight and heated in air at 550 for si2
.
hours to give gallium o~ide (6% wt. gallium) on eta-aluminac
'~ 4,9 g gallium nitrate~ Ga(N03)3~ 8H20, dissolved in 15 ml
~," distilled water Na9 added to 13 g Crosfield~ U 40 silica suspended
.: .
~s,i in 15 ml distilled water. The mixture was evaporated to dryness
,,;~ in a vacuum oven overnight nnd heated in eir at 550 for six
1 hours to give gallium o~ide (6% wt. galllum) on silica,
, . .
.'.~ .
' ~'", ' .
:j
~, ~ 6 -
:',
.: .~ , . - :
.. . .
_reparation e~ ~allium e~chlJn~ed silica cataly~t
4~0 g of Crosfield~ U 40 ~ilica 6el waq hydroly~ed by
standing under 1 1 distillsd water for ~ day~, The _ilica gel
was decanted A~y and stood undsr 4 1 of 2N nitric acid for 6 hours,
and then finally washed with 12 1 of distilled water in a
Buchner funnel. The silica ~el was dried at 200 C for 72 hour~
and calcined at 500C in air for 72 hour~.
4.5 g of gallium nitrate, Ga(N03)3, 9H20, was dis~olved in
200 ml o~ distilled water. 30 ml of the prepared ~ilica gel was
packed into a glnss column and the gallium nitrate solution ~as
percolated through the column for 18 hourq, The catalyqt was
finally washed with 1500 ml of di~tilled water and dried in a
vacuum oven overnight. The gallium exchanged silica catalyst (0.6
wt. gallium) was heated in air at 550C for 6 hours before u3e.
Similarly catalyst3 containing higher percentage of gallium
~, (e,g. 1.8% wt. Ga) were prepared by exchanging ~urther quantitie~
o~ ~allium nitrate under controlled pH condition~q.
Preparation of Ga20_/silica catal~st
; 4.9 g gallium nitrate, Ga(N03)3, 8H20 dis~olved in 15 ml
i~ 20 diqtilled water was added to 13 g Crosfields U 40 silica su~pended
ln 15 ml distilled water. The mixture was evaporated to dryness
in a vaouum oven overnight and heated in air at 550 for six hours
~i, to give gallium oxide ~6~o wt. gallium) on silica.
'~ EXAMPLE 1
~ When di-isobutene was passed over a gallium exchanged silica
-~ catalyst (1~8~o wt. gsllium) at a reaction temperature of 600C
at 5.1 sec, re~idence time, 99.~/o of the di-isobutene ~as converted.
The Ina~or ~oduots (expre~sed as percent weight yield) were C1-C3
-, hydrocarbons (14.~/~), C4 hydrocarbons (48~T~o) and aromatic3 (32.7~),
~ 30 Xylenes made up 22~o ~eight yield of the aromatics,
u ':
~ 7 _
'^ :
. . ,~ .: . . . . . . .
:~3~5
.. :; ~
When isobutene ~a~ pas~ed over a gallium o~lde (6~o wt. ~lium)/
eta-alumina catalyst at a re~¢tion temparature of 550C and a
re3idence time of 5~5 sec. arter 1.5 minute~ on stream 96.3% of
the i30butene was conv~rted. ~rhe ma~or product~ (expressed as
percent weight yield~ were butene~ (7.5~o), butanes (15~o), Ct-C3
hydrocarbon~ (26,~o) and aromatics (47'~'o). ~ylenes made up 25.7
weight yield of the aromatics. With total C4'~ recycle the
æelectivity to aromatics i~ 60.6~o and to ~ylene~ 33.2%,
EXAMPLE 3
The catalyst of Example 2 was reacti~atel in air at 550C
-
and under similar conditions to E~ample 1 but after 10 minutes
on stream gave 88~7~o conversion of i~obutene. ~he major products
(expressed as percent weight yield) were butenes (21 ~8~o) ~ butane~
ii (22~8%)~ C1-a3 hydrocarbons (19,7U/~), and aromatics (28/1~o).
Xylenes made up 15~3yu weight yield o~ the aromatics. With total
C4ls recycle the selectivity to aromatics i~ 50.7,a~ and to 2ylenes
:: 27, 6a~0.
: . ,~
EXAMPLE 4
When isobutene was passed over a ~allium oxide (6% wt. gallium)
i on gilica catalyst at a reaction temperature of 550 and a re~idence
. time of 5,9 sec.~ after 1.5 minutes on ~tream 49.1% of the isobutene:
'-'J,i,; ~ was converted. The maJor products (expressed as percent weight
~ yield) were butenes (66.7~), butanes (7~2~o)~ C1-C3 hydro~arbons
,:.
~ (4.6'~Ç), and aromatic3 (16.4,'~)~ Xylenes made up 11, ~ weight yield
.: . . ..
~ ; of the aromat~cs, With total C4'~ recycle the selecti~ity to
`~ aromatic~ is 63.3% and to ~ylenes 45.4~o~ The actlvity WQ~ unchanged'i~
~ ; after one hour on stream.
':`~ ~
,t ~, 0~ %
When i~obut~ne was passed over a gallium o~ide ~ wt. gallium)
~ 8 -
,:,'
. .~ .
,
.;
~,'`:'` . ~ ` , .
on ailica catRly~t at B reaation temparature of 590 and a
; r~sidencQ tim~ of 6.2 ~ec., aft~r 2.5 minut~s on stream 65,1% of
isobutene was con~erted, Ths ma,jor products (expresoed a~ percant
wei~ht yield) were butanes (39,3~10), butenes (38.7'~o)~ Cl c3
hydrocarbons (9,4~jo), and aromatlc~ (9,2J~)~ Xylene~ made up 6,5yo
.,
~; weight yield of the aromatic~. With total C4~ recycle the
.. , :
selectivity to aromatics is 42,4~o and to xylenee 29, 9%, The
~; activity was unchanged after one hour on stream~
. .
EX~MPLE 6
In thi~ example the support wa~ a ~ a containing surface
~, hydroxyl group~ exchanged with aluminium ions.
When isobutene was passed over gallium oxide (3% wt. gallium)/
aluminium (0,8~% wt.)/silica cat~yst at a reaction temperature of
600C and a rssidence time of 6.3 second~, after 2.5 minutes on
tream 72.~/o of the isobutene was converted. The major product3
;~ (expressed as percent weight yield) were butenes (46~5~o)~ butanes
(8,7%), C1-C3 hydrocarbons (14~4~%) and aromatics (23',~). Xylenes
made up 14,6yo weight yield of the aromatics and with total C4~s
recyole at con~tant activity, the selectivity to aromatics was 51.5v,o
and to xylenes 32.7%,
EXA~LE 7
~hen propylene wa~ passed over the gallium exchanged silica
catalyst (0.6/Cv wt, gallium) at a reaction temperature of 650
and a residence time of 5.2 sec., a~ter 2,5 minute~ on ~tream 50F/o
o~ propylene wa~ converted. ~he major products wsre C1-C3 j~
'?~ ~ hydrocarbon~, 23.5,~ wt., an~ aromatic~ 21,1,~ wt. Ben~ene mAde up
9.9~v wt. yield o~ the aromati~. With total propylene reoycle the
se]ectivity to aromatics is 42,2~ an-l to benzene 19,8~o.
. ~ . .
~en isobutene w~s p~ssed over the gallium exchanged siliaa
~ 30 catalyst (6% wt. gallium) at a reRction temperature of 600C and
,-"~
i . . .. .. . . .. , . . . . . . . - . . . .
5~
~q re~idenoe time of 6 ~eo, ~ft~r 2,5 minutes on ~tream 74.9% of
isobutenfl was convarted. The maJor pro~lucts (e~pre~3ed a~ percent
wei~,ht yield) were butenes (350/fo~ butanes (4.87~o)~ C1-C3 hydrooarbon~
(8.~), and aromatics (25%). Xyle~es made up 18.6,~ weight yield
of the aromatio~. With total C 'e rocycle the ~electivity to
" ' ~5 ~ 4
aroma~ic~ is~ and to xylenes 5~,3%, The activity NQ~ unchanged
after one hour on stream.
PIE ~
'~ ~hen 3 methylbutene-1 was passed oYer the gal]ium ex~hanged
silica cataly~t (o.6!~ wt. gallium) at a reaction temperature of
650C at 6 sec. residence time, after 15 minute~ on stream 97,~ oY
3-methylbutene-1 was converted. The major products (expressed as
percent weight yield) were C1-C~ hydrocarbon~ (33,8%), C4
hydro¢arbons (7.2~) and aromatic~ (39.~/o).
, ~XA~PL~ 10
An isobutene feed wa~ passed over a gallium (1. ~o wt. Ga)
exohanged ~ilioa catalyst at atmospheric pre~ure, a temperatura o~
200C and a contaot time of 1005 seconds. 67.8~ f the isobutene
.~ ,~, .
~ fed was converted to give 43,8% wt. of open chain C~ isomers and
''~ 20 14.48 wt. of open chain C12 isomers.
,`~ Using the same ontaly~t a~ ~xample lO above but using ~-methyl-
butene-1 as ~eed and a contAct time of 11.7 seconds, 6.2~o wt.
(59.6~J selectivity) of open chain C10 i~omer~ were ~ormed.
. J
' ~
"
.
'''~
.'~'1
;~i :
' 1 -- 10 --
' ''1
'~' ., .
.,j
