Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
WO 92/04977 2 0 9 2 ~ 6 9 PCI'/US91/06999
LEWIS ACID PROMOTED TRANSITION ALUMINA CATALYSTS
AND
ISOPARAFFiN ALK f LATI~N PROCESSES USING THOSE CATALYSTS
RELATED APPLICATI,~)N~
This is a continuation-in-part of U.S. Patent Application No. 07/697,318,
filed May 7, 1991, which in ~urn is a continuation-in-part of U.S. Patent Application
No. 07/588,448, filed September 26, 19g0, and alss a continuation-in-part of U.S.
Patent Application No. 07/6g7,320, filed May 7, 19~1, ths entirety of which are
-, incorporated by reference.
FIELD QF THE iNVENTlON
This invention is to: a.) a catalyst system, b.) a component of that system
comprising certain trsnsition aluminas promoted with a Lewis acid (preferab!y
BF3), and c.) a cata~ic process for the al,kylation of isoparaffin with olefins. The
catalyst component is produc0d by contacting th~ transition alumina with th~
Lewis acid at relatively low temperatures. The catalyst system comprises that
~omponent and an add~ional amount of fr0e Lewis acid. ~e process entails
olefin/isoparaffin alkylation using the catalyst component and '~s allied catalyst
- system.
BAC~KGROuND C)F THE INVENTION
The preparation of high octane blending components ~or motor fiJels using
strong acid alkylation processes (notably where the acid is hydrofluoric acid orsulfuric acid) is well-known. Alkylation is the reaction in which an alkyl group is
added to an arganic molecule, typically an arornatic or olefinic molecule. For
30 production of gasoline blending stocks, thc reaction is bc~ween an isoparaffin and
an olefin. Alkylation processes have been in wide use since World War ll when
.
high octane gasolines were needed to satis~y deman~s from high compression
'' ratio or supercharged aircraft engines. The ear~ alkylation units were built in
conjunction with fluid catalytic cracking units to take advantage of the light end by-
35 products of the cracking units: isoparamns and olefins. Fluidized ca~aly~ic
cracking units still constitute the major source of feedstocks for gasoline alkylation
units. In spite of the mature state o~ strong acid alkylation technology, existing
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problems with the hydrofluoric and su~ric acid technologies continue to be
sev~ disposal of the used acid, unintentional ~mission of the acids during use
or storage, substantial corros~vity of the aoid catalyst systems, and other
environmental concerns.
Although a practical alkylation process using solid acid ca~atysts ha~ng little
or no corrosive components has long been a goal, commercially viable processes
do not exist.
The open literature shows several systems used to alkylate various
hydrocarbon feedstocks.
The Arn~rican Oil Company obtainsd a s~ries of patents in the mid-1950's
on alkylation processes involving C2-C,2 ~preferably C2 or C3) olefins and C4-C8isoparaffins. The catalysts used were BF3-treated solids and the catalyst system(as used in the alkylation process) also contained free BF3. A summary of those
patents is found in the following list:
Patent No. Inventor F3-Treated Catalys~with free BF3)
2,804,491 May et al. Si02 stabilized Al2O3 (10Yo 60% by weight
BF~)
2,824,146 Kelly et al. metal pyrophosphats hydrate
2,824,150 Knight et al. metal su~ate hydrate
2,824,151 Kelly et al. metal stannate hydrate
; 2,824,152 Knight et al. metal silicate hydrate
2,824,153 Kelly et al. metal orthophosphate hydrate
2,824,154 Knight et al. metal tripolyphosphate hydrate
; 25 2,824,155 Knight et al. metal pyroarsenate hydrate
2,824,156 Kelly et a!. Co or Mg arsenate hydrate
2,824,157 Kni~ht ~l. Co, ~, or Ni borate hydrate
; 2,824,158 Kelly et al. metal pyroantimonate hydrate salt
2,824,159 KellyQ~31. Co or Fe molybda~e hydrate
2,R24,160 Knight et al. Al, Co, or Nitungstate hydrate
2,824,161 Knight et al. borotungstic acid hydrate or Ni or Cd
borotungstate hydrate
2,824,162 Knight et al. phosphomolybdic acid hydrate
2,945,g07 Knight et al. solid gel alumina (5~100% by weight of
Zn or Cu fluoborate, pre~erably
anhydrous)
~may be supwr:ed on Al2O3
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None of these discloses a process for alkylating olefins and isoparaffins using
neat ~iumina treated with BF3.
Related catalysts have been used to oligomerize olefins. U.~. Pat~ ~e
2,748,0g0 to Watkins suggests the use of a catalyst made up of a Grc
metal (preferably nickel), a phosphoric add tpr~ferab~ containing pt~ ~J
pentoxide~, all placed on an alumina adsor~nt, and pretreated with
Alkylation of aromatics is suggested.
U.S. Patent No. 2,976,338 to Thomas suggests a polymerization ca'a yst
comprising a complex of BF3 or H3PO4 optionally on an adsorbent (~ ~, as
activated carbon) or a molecular sievs optionally containing potass~ ~ ~
fluoride. a ~ ~
Certain references suggest the use of alumina-containing c~ ~ ~.or
alkylation of aromatic compounds. U.S. Patent No. 3,068,301 to HeNert et al.
suggests a catalyst for alkylating aromatics using Uolefi~b-acting compounds. Tha
catalyst is a solid, silica-stabilized alumina containing up to 1096 Sit:~2, all of which
has been modified with up to 100% by weight of BF3. None of the~ie prior
references suggest either the process nor the material used in the processes as is
disclosed here.
Other BF3-treated aluminas are known. For instance, U.S. Patent No.
3,114,785 to Hervert et al. suggests the use of a eF3-modified, substantially
anhydrous alumina to shffl the double bond of 1-butene to produce 2-butene.
The preferred alumina is substantially anhydrous gamma-alumina, eta-alumina, or
theta-alurnina. The various aluminas will adsorb or complex with up to abou~ 19%by weight fluorine dependin~ upon the type of alumina anJ the temperature of
treatment, The aluminas are treated w'lth BF3 at ~Isvated ternperatures. Hervert et
Ql. does not suggest using these catalysts in alkylation reactions.
In tJ.S. Patent No. 4,407,731 to Imai; a high surface area me~al oxide such
as alumina (particularly gamma-alumina, eta-alumina, theta-alumina, silica, or asilica-alumina~ is used as a base or support for BF3. The BF3 treated metal oxide
is used for generic oligomerization and alkylation reactions. The metal oxide istreated in a complicated fashion prior to being treated with BF3. The first stepentails treating the metal oxide with an acid solution and with a basic aqueous
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solution. The suppor~ is washed with an aqueous decomposable salt such as
amm~nium nitrate. The support is washed using deionized H20 until the wash
water shows no alkali or aikaline earth metal cations in the filtrate. The support is
dried and calcined. The disclosure suggests generically that BF3 is then
5 introduced to the treated metal oxid~ support. Th~ sxamples show introduction of
the BF3 at elevated temperatures, e.g, 300 C or 350 C.
Similarly, U.S. Patent No. 4,427,791 to Miale et al. suggests the
i enhancement of the acid catalytic activity of inorganic oxide rnaterials (such as
alumina or gallia) by conta~ing the material with ammonium fluoridc or boron
- 10 ~contacting the treated inorganic oxide with an aqueous ammonium
1~ or salt solution, and calcining the resulting material. The inorganic
oxides ~eated in this way are said to exhibit enhanc~d Bronste~ acidity and,
therefore, are said to have improved acid activity towards the catalysis of
numerous reactionsF~such as alkylation and isomerization of various hydrocarbon
compounds). A specific suggested use for the treated inorganic oxide is as a
matrix or support for various zeolite materials ultimately used in acid cataly~ed
organic compound conversion processes.
U.S. Patent No. 4,751,341 to Rodewald shows a process for treating a
ZSM-5 type zeolite with BF3 to reduce its pore size, enhance its shape selectrvity,
and increase its activity towards the reaction of oligomerizing olefins. The patent
also suggests using these materials for alkylation of aromatic compounds.
Certain Soviet publications suggest the use of Al203 catalysts for alkylation
processes. Benzene alkyla~ion using those cata~sts (with 3 ppm to 5 ppm water
and periodic additions of BF3) is shown in Yagubov, Kh. M. et al., erb. Khim
Zh" 1984, (5) p. 58. Similarly, Kozorezov, Yu and Levitskii, E.A., Zh. Print. Khim.
~Leningrad), 1984, 57 (12), p. 2681, show the use of alumina which has been
heated at relatively high temperatures and modified with BF3 at 100 C. There areno indications that BF3 is maintained in excess. Isobutane alkylation using
Al203/BF3 catalysts is suggested in Neftekhim!ya, 1977, 17 (3), p. 396; 1979, 19(3), p. 385. The olefin is ethylene. There is no indication that BF3 is maintained in
excess during the reaction. The crystalline form of the alumina is not described.
U.S. Patent No. 4,918,255 to Chou et al. suggests a process for the
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WO 92/04977 2 ~ 9 2 t~ 6 9 PCr/US91/06999
alkylation of isoparaffins and olefins using a composite described as "comprising a
Lewis acid and a large pore zeollte and/or a non-zeolitic inorganic oxide~. The
process disclosed requires isomerization of the olefin feed to reduoe substantially
the content of a!pha-olefin and further suggests that water add~ion to the
5 alkylation proc~ss improves the operation of the process. The best R~search
Octane Number (RON) product madc using the inorsanic oxides ~in particiJlar
SiO2) is shown in Table 6 to be 94Ø
Similariy, PCT published applications WO 90/00533 and ~0/00534 (which
ars based in part on the U.S. patent to Chou at al. noted a~ove~ suggest the
sarne process as does Chou et al. WO 90/00534 is specKic to a process using
boron trifluoride-treated inorganic oxides including ~umina, sitica, boria, oxides of
phosphorus, titanium oxide, zirconium oxide, chrornia, zinc oxide, magnesia,
calcium oxide, silica-alumina-zirconia, chromia-alumina, alumina-boria, silica-
zirconia, and the various naturally occurring inorganic oxides of various states of
15 purity such as bauxite, clay and diatomaceous earth~. Of special note is the
i statement that the ~preferred inorganic oxides are amorphous silicon dioxid0 and
aluminum oxide". The examples show the use of amorphous silica (and BF3) to
produce alkylates having an RON of no greater than 94.
None of these disclosures shows crystalline transition aluminas which were
20 promoted with Lewis acids at lower tempera~ures nor any effect upon the NMR
spectrum because of such a treatment. Nor do these disclosur0s show their use
in isoparaffin/olefin alkylation. These disclosures h~rther do not show any benefit
to the alkylation of isoparamns and olefins using these spccRically treated
aluminas.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures lA-1D are nuclear magnetic resonance ~NMR) plots of certain
transition aluminas treated with BF3 at a range of temperatures.
Figure 2 is a three-dimensional graph showing octane sensitivity for the
30 inventive process as a function of olefin feed content.
W O 92/04977 2 0 9 2 ~ ~ 9 PC~r/US91/06999~
SUMMARY OF THE INVENTION
-This invention is variousiy a cata~st componen~ comprising one or more
transitional aluminas which are treated with one or more Lewis adds (preferably
BF3) at a fairly low temperature desirab~ so low that the component exhibits
specific NMR spectra, a catalyst systëm comprising that catalyst componert w~th
excess Lewis acid, and an olefin/isoparaffin alkyation process step using that
cataiyst system.
Use ~f the catalyst system, i.e., the catalyst component in conjunction with
excess Lewis acid, producss high octane alkylate from isobutan~ and butylene at
a variety of reaction temperatures between -30'' C and 40 C. The catalyst's highac~ivity can result in low operating costs bacause o~ its ability to operate at high
space velocities.
DESCPllPTlON OF THE INVENTION
This invention is:
A) a catalyst component comprising certain Lewis acid treated transition
aluminas,
B) a catalyst system comprising the catalyst component in combination
with at least a minor amount of free Lewis acid, and
C) an alkylation process for producing branched paraffinic products
from olefins and isoparaffins using that catalyst system.
The Catalyst C~omponent
The catalyst component of this invantion comprises or consists essentiatly
of a major amount of transition aluminas (preferably eta- c~r gamma-alumina)
which has been treated with a Lewis acid, preferably BF3. The catalyst
component is acidic in nature and contains substantially no metals (except, of
course, aluminum and the semi-metal boron) in catalytic amounts capable of
- hydrogenating the hydrocarbons present in the feeds except those metals may be
` present in ~race amounts in the Lewis acid or the alumina.
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Alumina
Aluminum oxide (alumina) occurs abundantly in nature, usually in the form
of a hydroxide in the mineral bauxite, along with other oxidic impuritles such as
Tl02, Fe203, and SiO2. The Bayer process is used to produce a reasonably pure
5 Al2O3 having a minor amount of Na2O. The Bayer process may be us0d to
produce a variety of alumina hydroxides:
Material Common ~lam~ ~!aQ H-OJAt2Q3 CAS Index N~,
~-trihydrate hydrargill~e/gibbsi~e 35 3.0 14762~93
~-trihydrate bayerite 35 3.0 20257-20 9 or
1 2252-72-1
~-trihydrate nordstrandite 35 3.0 13840 05 6
~-monohydrate boehmite 15 ~.0 1318-23
hydrate psuedoboehmite 2~ 2.0
The aluminum hydroxides may then be treated by heating to produca various
activated or transition aluminas. For instance, the aluminum hy~roxide known as
boehmite may be heated to form a sequenc~ of transition phase aluminas:
gamma, detta, theta, and finally, alpha (see Wefers et al., "Oxides and Hydroxides
20 of AiuminaU, Technical Paper No. 1g, Aluminum Company of America, Pittsburgh, PA, 1972, pp.1-51).
Transition aluminas (and their crystalline forms) include-
gamma tetragonal
dclta orthorhombic/tetragonal
eta cubic
theta monoclinic
chi cubic/hexagonal
kappa hexagonal
' 30 lambda orthorhombic
,
~, A~vated aluminas and aluminum hydroxides are used in various chemical
` processes as catatyst and adsorbents.
35 The alurninas suitable for use in this process include the noted transition
aluminas: gamma, delta, eta, theta, chi, kappa, or lambda. Especially preferred
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are gamma- and eta-aluminas. Mixtures of the two ara also desireable.
Since it is difficult to produce a substantial~ pure single phase transition
alumina, mixtures of various aluminas are tolerable so long as a major amount ofthe specified alumina is pres~nt in the catalyst. For instance, in the production of
eta-alumina, gamma-alumina is often cQncurren~y present in the resulting product.
Indeed, x-ray diffraction ana~sis can only difficu~y detect ths dfflerence between
the two phases. Aluminum hydroxides (boehmi~e, gibbsite, etc.) may be present
in the predominately transition phase product in more ~han trivial amounts so long
as they do not substantially affect the desired alkylation reaction.
The alumina may be produc2d in any appropriate form such as pellet,
granules, bead, sphere, powder, or other shape to facilltate Its use in fi~ed bed,
moving bed, slurry, or fluidked bed reactors.
Lewi~Qs~s
The catalyst component of this invention contains one or more L~wis acids
in conJunction with the alumina notad above. A Lewis acid is a molecule which
can forrn another molecule or an ion by forming a complex in which it accepts two
electrons from a seeond molecule or ion. Typical strong Lewis acids include
boron halides such as BF3, BC13, BBr3, and Bl3; antimony pentafluoride (SbFs);
aluminum halides (AIC13 and AlBr3); titanium halides such as TiBr4, rlC14, and TiCI3;
zirconium tetrachloride (ZrC14); phosphorus pentafluoride (~Fs); iron halides such
as FeCI3 and FeBr3; and the like. Weaker Lewis acids such as tin, indium,
bismuth, zinc, or mercury halides are also acceptable. Preferred Lewis acids are
, . ..
boron containing materials (BF3, BC13, BBr3, and Bl~, SbF5, and AIC13; most
preferred is BF3.
The Lewis acid typically forms complexes or surface compounds with the
i .
alumina substrate. For instance, BF3 forms aluminum ~uoroborate sites with the
hydroxyl groups found at the alumina surface an~ additionally is physi-sorbed atthe alumina surface.
- 30 The total amount of Lewis acid in the alumina surface is between 0.5% and
40% by weight of the catalyst depending in large measure on two factors: the
Lewis acld chosen and the susceptiùility of the alumina surface to acceptng the
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Lewis acid by chemisorption or by physisorption. In the case of BF3, we believe
that 5-20% of the weight of the alumina catalyst component is attribu~ble to BF3products (e.g., the production of aluminum fluoroborate or similar compounds)
and the remainder is physi-sorbed BF3.
To mairltain the presence of sufFicient Lewis acid on th~ catalyst
composition, we have found it desirable to maintain at least a minor amount of the
Lewis acid in the proxirnity of the alumina surface, preferably in the reaction fluid.
This amount is an amount at least sufficient to maintain the concentration of the
Lewis acid spesified above on the alumina. At ~he WHSV ranges specified abov~
with regard to the alkylation reaction, we have found ~at generally an amour~ ofat Isast 0.5% of Lewis acid (based on the hydrocarbon) is sufficier~t to maintain
the Lewis acid level on the alumina. On an alumina basis, the ratio of free Lewis
acid ~that is, Lewis acid in the proximity o~ the alumina but not associated wth the
alumina by chemisorption or physisorption) to alumina is in the range of 0.05 to25 g Lewis acid/g Al203. For BF3 the preferred range is 0.15 to 20 g BF3/g Al2O3,
is more preferably in the range of 0.20 to 15 9 BF3/~ Al2O3, and is most preferably
in the range of 0.10 to 15 9 BF3/g Al2O3.
(::atalyst Corn~onent Preparation
The catalyst component may be prepared in situ in, e.g., an alkylation
reactor by passing the Lewis acid in gaseous form through the vessel containing
the transition alumina. Alternatively, the alumina may be contacted with the Lewis
acid and later introduced into the reactor.
In any case, the alumina may be substantlally dry or anhydrous prior to
contact with the Lewis acid and maintained in a state of d~ness, i.e., maintained
at a very low free H20 content. The alumina phase chosen in con3unction with
proper treatment of the alumina to maintain the presence of hydroxyl groups
(usually by maintaining the alumina at temperatures below 4~0 C during
,i pretreatment) allows the presence of about 4-10 hydroxyl groups per 100 A2 of
alumina surface area. Preferred is 6-10 hydroxyl groups per 100 A2 of alumina
surfaca area. The alumina is preferably completely hydroxylated since that
hydroxylation, in turn, permits the forrnation of the maximum amount of the Al-OH-
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Lewis acid complex, believed to be one 81ement of the ac~ive alkylation catalyst at
the alumina surface. The alurnina may be par~ially or substantial~ dehydroxyiated
but the catalyst is not as emcacious.
Additionally, free water (in distinction to the water wtich may be identified
5 as hydroxyl groups on the alumina surface) may ba present in limited amounts in
the alumina. The free water content in the alumina may range between 0.0 and
10~ by weight but preferably is between about 0.0 and abou~ 5.0 %. ~ the Lewis
acid chosen is ~F3, the free water content of the a~umina may be between 0.0 and4.0 % (by weight), preferably between 1.0 and 3.5 %, and most preferably
10 between 2.~ and 3.5 %. Higher amounts of water appear both to degrade the
cata~st and to impair the effectiveness of the catalyst in the practice of the
alkylation reaction. Higher amounts of water also tend to form cornpounds, such
as BF3 hydrates, which are corrosive and therefore undesirable.
Contact temperatures between -25- C and less than about 150' C are
acceptable; a temperature between -25-C and 100-C is desirable; a temperatur0
between -30- C and 30- C is preferred. The partial pressure of gaseous Lewis
acid added to the alumina is not particularly important so long as a sufficient
amount of Lewis acid is added to the alumina. We have found that treatment of
the alumina with BF3 at the noted temperatures will result in an alumina-BF3
20 complex containing BF3 sufficient to carry out the alkylation. The alumina contains
between 0.5% and 3~h by weight of BF3. We have observed that solid state
boron-nuclear magnetic resonance (l'B-NM~) analysis of the catalyst component
provides evidence (a pronounced peak at about -~1.27 ppm relative to boric acid)of tetragonal boron in the catalyst composite produced at the lower temperatures.
25 Aluminas treated at temperatures of 150- C and higher do not show these spectra
. ~ but instead show evidence of trigonal symmetry about the boron. Acceptably
` ~ active catalysts are those in which the relative amounts of trigonal
boron:tetragonal boron ~as calculated by the integration of the respec~ive 1'B-NMR
spectra) are in the range of 0 to 0.5. The lower the value of the ratio, the more
- 30 effective the catalyst has been found to be in alkylation reactions. More preferred
is the range of 0.0 to 0.25; most preferred is 0.0 to 0.1.
Additionally, we have observed that when the elumina substrates are
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heated at temperatures above about ~0 C before they are contacted with the
Lewis acid BF3, that certain areas of the infrar~ spectra are modi~ed. The
Fourier Transform Infrared (FT R) absorbances at about 1557 and 1510 cm ~
which we observe when th~ alumina is treatcd a~ temperatures below that level
5 disappear above this temperature. Although wa believe that the disappearanc~ of
those IR spectral absorbances is somehow related to the decomposition of tha
key surface intermediates involved in the ca~a~ic function, we do not wish to bebound to this theory.
Obviously, the alumina may be incorporateJ into a binder prior to its
10 treatmerlt with Lewis acid. The binders may be ~ays (suoh as morltmorillon~e
and kaolin) or silica based materials (such as gels or o~her gelatinous
precipitates). Other binder materials include carbon and metal oxides such as
alumina, silica, titania, zirconia, and mixtures of those metal oxides. The
composition of the binders is not particularly critical but care must be taken that
15 they not substantially interfere with the operation of the alkylation reaction.
The pr~ferred method for incorporating the cata~ic alumina into the binder
is by mixing an aluminum hydroxide precursor (such as boehmite) with the binder
precursor, forming the desired shape, and calcining at a temperature which both
converts the aluminum hydroxide precursor into the appropriate transition phase
20 and causes the binder precursor to bind the alumina par~icles. The absolut0
upper temperature limit for this calcination is about 1150~ C. Temperatures below
about 1000- C may be appropriate.
Alkylation Process
The inventive catalyst component and the allied catalyst composition are
especially suitable for use in alkylation processes involving the contact of an
isoparaffin with an olefin. The catalyst component should be used in conjunctionwith an amount of free Lewis acid.
Specifically, the catalyst system (the inventive catalyst component in
30 combina~ion with a ~ree Lewis acid) is active in alkylation reactions at low
temperatures (as low as ~ C) as well as a~ higher temperatures (nearing 50 C).
Lower tempera~ures (-5~ C to 15~ C) are preierred beoause of the enhanced
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WO 92/04977 2 ~ 9 2 5 ~ 9 pCT'/l.J~i91~06999~
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octane of the alkylate produced and are particularly preferred if the feedstreamcontains more than about 1% isob~ylene. Higher temperatures also tend to
- produce larger amounts of po!ymeric materials.
The pressure used in this process may be between atmospheric pressure
5 and about 7~ psig. t~igher pressures within the range aliow recovery of excessreactar~s by flashing a~er the product stream leavles the alkylation reactor. The
amount of catalyst used in this process depends upon a wide variety of disparatevariabies. Nevertheless, the Weight Hourly Space Velocity (~WHSV~' = weight of
olefin feed/hour~ weight of catalyst) may effe~ively be beh~een 0.1 and 120,
10 especially between 0.5 and 30. The overall mo~ar ratio of isoparamn to olefin may
be between about 1.0 and 50Ø Preferred ranges include 2.0 and 25.0; the more
preferred include 3.0 and 15Ø
The feedstreams introduced to the catalyst are desirably chiefly isoparaffins
having from four to ten carbon atoms and, most preferably, four to six carbon
15 atoms. Isobutane is most preferred because of its ability to make high octanealkylate. The olefins desirably contain from thre0 to twelve and preferably from- thra~ to five carbon atoms, i.e., propylene, cis- and trans-butene-2, butene-1, and
amylene(s). Preferably, the olefin stream contains little (if any) isobutylene.
Similarly, for the inventive catalysts the process works better in producing hi~h
20 octane alkylate if the feedstream contains little or no butadiene (preferably less
than 0.2% to 0.3% molar of the total olefins) and a minimal amount of isobu~ylene,
` ~ e.g., less than about 2.5% molar based on the olefins. Although the catalyst
alkylates butene-1, it is preferred to operate with a minimum of butene-1, e.g., less
than about 10% by mol, since It lowers the octane values of the resulting alkylate.
25 Of coursel if it is desired to operate a process with high throughput rather than
with highest octane, a higher level of butene-1 is tolerable. An excellent source of
a feedstock containing a low level of isobutylene is the ramnate from a process
which produces methyl-t-butylether (MTBE).
The water content of the feedstocks may vary within wide limits, but
30 preferably is at a low level. The water content shoul~ be less than about 200ppmw and most preferably less than abou~ 50 ppmw. Higher levels of water
content tend to lower the octane value of the resulting alkylate and form corrosive
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hydrates or reaction products with the Lewis acids
The feeds~ocks should contain a minirnum of oxygenates such as ~thers
and alcohois. Oxygenates appear to lessen substantially the effec~iveness of thecatalyst system.
The produc~s of this alkylation process typical~ oontain a complex mix~ura
of highly branched alkanes. For instance, when using isobutane as the alkana
and n-butylene as the olefin, a mixture of 2,2,3-; 2,2,4-; 2,3,3-; and 2,3,~
trimethylpentane (TMP) will result often with minor amounts of other isomeric orpolymsric products. The 2,3,~T~P isomer is the lowest oc~ane isomer of the
noted set. The 2,2,~ and 2,2,4-TMP isomers are higher octane eomponertts.
Calculated average oc~ane values (RON plus Motor Octans Number [MON~/2) of
the various C8 isomers are:
.
Isomer Q~D~
'' 15
; 2,2,3- 104.8
2,2,4- 1 00.0
2,3,3- 1 ~2.8
2,3,4- gg
Thz process may be carried out in the liquid, vapor, or mixed liquid and
; vapor phase. Uquid phase operation is preferred.
. :
The invention has been disclosed by direct description. Below may be
found a number of examples showing various aspects of the invention. The
examples are only examples of the invention and are not to be used to limit the
scope of the invention in any way.
. .
; 30
EXAMPLES
:'',
am~ ~talyst TestinQ
This example shows the preparation of a number of alumina-based
35 catalysts in situ and their subsequent use in an alkylation rear,tion using model
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WO 92/~4977 ~ O 9 2 5 6 9 Pcrlus
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feeds. It is used to evaluate catalyst activity and selectiv~y.
The alumina samples wer~ dried at 150- C overnight and charged to a
semi-batch reactor having an intemal volume of about 500 cc. The reactor
temperature was cnntrollable over the range of -5' C to 40 C. For initial eatalyst
- 5 treatment, the reactor containing the catalyst was purged wi~ an inert gas and
cooled to about 0- C. About 275 cc of isobuta ~c was added to the reactor. Aftera brief degassing, BF3 was added batchwise. After BF3 is added, the pressure
typicaily drops as the alumina adsorbs or rea~s with the BF3. Acld~ionai infusions
of BF3 are made until the pressur0 in the reactor no longer drops. Ths BF3
saturation equilibrium pressure was about 40 psig. The liquid phase conoentration
of BF3 was about 1.5%. At that point the alumina had adsorbed or reacted with all
of the BF3 possible at that temperature and the catalyst was in its most actNe
form.
A 4/1 molar mixture of isobutana and trans-2-butene was added to the
reactor at a WHSV of 3.5 until the paraffin to olefin ratio reached 25.
The product alkylate was then removed from the reactor vessel and
analyzed using gas-liquid chromatography.
~: The results of those runs are shown in Table 1.
Tabl~ 1
~/OC8 in
~- AluminaATy~çSurfa~ Area Alkylate Prod~t
gamma 180 m2/gm 95.4
gamma 116 m2/gm 8~.07
delta 118 m2/gm 94.3
pseudoboehmite352 m2lgm 74.2
bayerite 40 m /gm 69.1
pseudoboehmite250 m2/gm 59.6
boehmite150 m2/gm 59.8
. . ~
It is clear from these preliminary screening da~a that the transition (gamma
and delta~ aluminas produce significantly higher percentages of C8 in the product
alkylate than do the other aluminum hydroxide catalysts. The result did not
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WO 92/0~977 P~/US91/06999
2~92 ~G9
appear to correlate to the specific surface area of the catalyst.
Ex~mple 2: Cata~st ~creening
This example compares the performance of eta-alumina (a preferred forrn
of the inventiYe catalyst) with representati~fe samples of other acidic oxides eadl
combined w~h BF3 for the reaction of isobutane wth butenes to produce alkylate.
The eta-alumina sample was prepared by a controlled thermal treatment of
bayerite (Versal B from LaRoche Chemicai) for 15 hours at 250 C and 24 hours at
- 500 C under a N2 atmosphere.
The comparative oxidic materials were: silica-alumina, synthetic mordenite
zeolite, and fumed siiica. The silica-alumina (obtained from Dav~son Chemical~
contained 86.5% SiO2 and had a surface area of 392 m2/gm. It was used without
;:~ further treatment.
The mordenite was a hydrogen form z001lte and was obtained from Toyo
- 15 Soda. It was prepared from Na-mordenit0 and sub~ected to ion exchange, steam
. . .
treatment, and calcination to achievo a Si/~ ratio of 28.
Each of the samples was dried at 150- C overnight and introduced into the
semi-batch reactor described in Example 1. The samples were pur~ed with a dry
inert gas and cooled to 0 C. Isobutane was added to the reac~or to an in~ial
volume of 100 cc. BF3 was added with stirring until an equilibrium pressure of 30
psig was obtained.
A mixture of isobutane/t-2-butene was fed to the reactor. At the completion
of ~he reaction, alkylate was removed and analyzed by gas-liquid chromatography.The RON were calculated from the gas-liquid chromatography data using the well-
known correlations in Hutson and Logan, "Estimate Alky Yield and Qual ty",
Hydrocarbon Processing, September, 1975, pp. 107-108. The summary of the
experiments and results is shown in the table below:
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Table 2
Eta- Silica- Dealuminated
Al2Q3 ~Qa Mord~n~ ~ilic~
Catalyst charge ~9) 3.5 3.7 2.4 1.8
Temperaturo ( C) 0 0 0
i-C4 charg~ ml (initial) 180 180 180 375
i-CJC~feed ratio ~molar) ~.2 5.9 5.9 9.5
Spacevelocity (WHSV~ 2.6 2.0 3.3 2.8
- Runtime (minutes) 36 34 28 58
i-CJC", (final) 23.5 30.3 34.0 57
.: ~ Butene conversion (%) 100 100 100 100
~ 15 Product analysis ~weight %):
. . - CS-C7 3.-1 5.2 11.3 13.0
~:: C8 saturates 95.7 75.8 71.7 70.9
: Cg+ 1.2 13.0 17.0 16.1
TMP/C:3 total (h) 93,0 91.2 91.3 91.6
Yield (w/w) 2.08 1.55 099 1.43
RON 99.3 94.6 93.0 93.0*
Octane (R~M/2) 97.9 93.1 92.0 92.1*
~estimated
25 Clearly, for the eta-alumina catalyst, the yield of C8's was sign~cantly higher; the
overall yield and RON were rnuch better.
Example 3
This example shows that the addition of aither water or methanol produces
no appreciable improvement on the alkylation of butene-~ wlth isobutane using ~he
inventive alumina catalyst. Indeed, water an~ rnetharlol appear to be detrimental.
Three separate semi-batch reactors were dried and flushed with nitrogen.
A sample of 2.5 gm of a gamma-alumina (LaRoche VGL) was loaded into each
bottle. The alumina samples had been previously dried at 110 C overnight. An
amount of 0.278 3ms of deioni~ed water was added dropwise ~o one rea~or. An
amount of 0.988 gms of methanol was added to another reactor. These amounts
.
were calculated ~o be 1Q% of the catalyst plus water eq~ivalen~. The remaining
reactor was used as a control reac~or. Isobutane (24~ cc) was added to each
bottle; BF3 was added (with stirring~ un~il the pressure reached a constant 30 psig.
A feeds~ock of 2/1: isobu~ane/2-butene was continuous~ added at a rate of 1.6
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WO 92/04977 2 ~ 9 ~ ~ 6 9 P~/US91/06999
cc/minute. The reac~ion continued for about 75 minutes after whioh samples of
th~ r-eactor liquids were extracted and anayzed using a gas-liquid chromatograph.
The conversion of olefin was more than 9996 in each case. Other reaction
conditions and a surnmary of reaction results are shown in the following tab!e:
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Rèaction Çon~itions Alurnira Alumina w/Ha~ Alumina
w/CH
Reaction temperature ( C) 0 0 0
Pressure (psig) 30.0 30.0 30.0
WHSV 5.6~3 5.526 5.526
1/0 (w/w) 10.3 10.63 10.63
Product
.~. . C5-C7 2.29h 2.80,6 14.85%
C8 (saturated) 94.61% 89.81% 64.67%
'; ~12t 2.52% 6.81% 13.58%
TMP/C8 98.74% 98.83,6 96.18%
`neld (w/w) 2.19 2.14 1.87
RON 100.05 98.19 93.49
R + M/2 98.32 9~.06 92.74
It is clear that neither water nor methanol created any advantage in the operation
of the process in producing a gasoline alkylate. The gross amounts of C~
- produced were smaller than for the inventive alurnina; the amount of undesirable
Cl2~ were two to four times higher than for the inventive alumina. The yields were
25 lower and, probably most importantly, the octane values of the comparative
products were significantly lower.
Examp!e 4
This example shows the suitability of the inventive catalyst (gamma-alumina,
30 LaP~oche GL) for a variety of olefin feedstocks. The following reaction conditions
were used for the tsst series:
.
Temperature 0 C
; 35 Total pressure 30 psig
WHSV 4
~,
A semi-batch reactor was utilized in each run.
The olefin feedstocks were mixtures which were chosen to allow us to
icientify desirable and undesirable combinations of feed materials. The mixtures
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WO 92/04977 PCltUS91/06999
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~0/40 mixhLr~ ~f
Mixt~re No. 1-C, i-C4_ C~ cis/tr~ns 2-Ç;
1 25 ~5 20 30
2 10 25 20 45
3 25 10 20 45
- 4 1~ 10 20 60
05 45
6 10 25 05 60
7 25 10 05 60
8 10 10 0~ 7s
,
15 The products made were analyzed using gas-liqu;d chromatography and their
respective octane numbers calculated as follows:
:'~
Mixture NQ.C5 ç7 C8 C12_ rMPICB 9QN R~M~2
1 14.4 55.0 23.7 94.1 86.3 86,3
2 15.3 52.9 25.9 93.6 86.3 87.1
3 15.4 58.B 20.2 94.9 88.7 87.9
4 14.5 60.8 17.0 95.1 ~0.9 90.1
10.2 66.4 17.9 92.6 89.9 88.9
6 7.3 62.g 2~.3 95.1 89.8 89.0
7 6.4 74.9 16.t 94.7 92.1 90.5
8 6.8 71.9 11.6 96.3 93.1 91.9
.
These data show tha~ increases in isobutene and propylene feed concentrations
directionally cause the inventive alkylation process to produce lower alkylate C8
content. As shown in Figure 1, srnaller amounts of elther C3~ or i-C4' caus0 no
more harm to alkylate quality but are generally undesirable H extremely high
35 octane alkyiates are necessary.
.,~,,'
Exam,Qle 5
This example demonstrates the performance of the transltion alumina/BF3
catalysts in reacting isobutane with butenes to form high octane product under
40 conditions of high space veloc~y and low paraffin/olefin feed ratios.
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WO 92/0~977 2 (~J 9 2 5 ~ ~ PCr/US91/06999 ~
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A sample of gamma-alumina tVGL, LaRoche) was dried overnight at 110- C
and loaded into the semi-continuous reactor unit desuibed in Example 1. The
catalyst was purged wi~h dry inert gas and cooled to 0 C. Isobutane was added
to ths reactor and then the system was exposed to BF3 under stirring conditions
5 until an equilibrium pressure of 30 psig was achieved. A feed comprising pure
: trans-2-butene was then pumped into the reactor under vigorous stirring
conditions over a period of 60 minutes; samples were obtained periodically during
the run. The results are summarized in the table below:
10 Catalyst charge (9) 2.5
: . Temperature ~C) 0
C~ initial charge (ml)` 300
Olefin fead Trans-2-butene
. I Space velocity (\NHSV) 26.4
Run time (minutes) 30 60
Equivalent external i-C~/C~ 5.4 2.6
~utene conversion ~%) 100 100
Product analysis (weight %):
20 Cs~C7 3.2 4.7
C8 saturates g~.1 81.9
- ~ Cg~ 5.7 13.4
TMP/C8 total (h) 97.6 g6.6
RON 99.0 96.8
Z5 Octane, R+M/2 97.0 95.3
~'~
,, Examp!e.
: ,,
This example shows the utility of the catalyst system on a feed obtained
from a refinery MTBE unit. The feed, containing minor amounts of butadiene and
isobutene, was introduced into a bed of a commercial hydroisomerization catalyst
(0.3% Pd on Al;2O3) at 400 cc/hr, 80- C, and 350 psig along with 14 sccm H2. Themolar ratio of H2:butadiene was 6:~. The thusly treated feed, containing no
butadiene and 0.52 % (molar) of isc~butene, was mixed with an appropriate
. ~ 35 amount of isobutane. The mixture had the following approximate composition:
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~ WO 92/04977 2 gl 9 2 ~ 6 9 Pcr/usgl/06999
-. .` `:
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Com~onent mole /0
propylene 0.02
propane 0.13
isobutane 80. 14
isobutene 0.52
1-butene 0.75
butadiene ~
n-butane 3.84
t-butene-2 8.23
~; lû c-butene-2 4.05
3-methyl-1-butene 0.01
isopentane 1.73
pentene 0.~1
2-methyl- i-butene 0.03
1~ n-pentane 0.08
t-2-pentene 0.13
~`, c-2-pentene 0.06
2-methyl-2-butene 0.23
,
.. .
This mixture had an isoparaffin/olefin ratio of 6.10 and an isobutane/olefin
, ratio of 5.69.
The mixture was th~n admitted to a pair of continuous laboratory reactors
each containing 280 cc of liquid and containing 5.04 9 of catalyst. The
temperature was mair~ained at 0 F. The WHSV for the reactor was 4.3 hr ~ and
the LHSV was -i.07 hr '. The catalyst was a gamma alumina ~ oche VGL) and
. , ,
; was prepared by adding the proper amount to the reactors along with a small
amount of isobutane, pressuring the reactor to about 40 psig of BF3, and
maintaining that pressure for the duration of the test.
The test was run for 41 hours total time. The catalyst was regenerated four
times during the run by rinsing the catalyst in ~OOcc of trimethyl pentane, heating
:,
;~ to 150- C in air for 45 minutes to volatilize a portion of the r~action prociuct on the
catalyst, and heating the catalyst to 6Q0 C in air for 60 minutes to oxidize thef ,'~, remaining hydrocarbonaceous materials. Small amounts of the catalyst were
- added as necessary with the regenerated catalyst to restore ~he catalyst to lts
,:,
proper amount upon retum to the reactor (0.41 9 @ cycie 2, 0.97 9 ~ cycle 3,
0.0 g @ cycle 4, and 0.47 9 @ cycle 5). About ~.5 liters (3.2 kg) of stripped C5+
alkylate was collected having about 7.6% C5,,, 81.2% C~, 4.4% Cg l1, and 6.8% C,2
:!
~ (all by weight). Using ~he Hutson method discussed above, the octanes were
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W092/04977 æa9~J~j~9 PCl/US91/06999
calculated to be: RON = g6.6, MON = 93.3, and the (R+M)/2 = 94.g5. The
product was then engine-tested using API methodology and the octanes were
measured to be: RON = 98.7, MON = 93.85. The resu~ing (R~M)/2 = 96.28.
The Hutson method clearly underestimated the RON octane values for this
5 process. ~:
';`~ :`"'
Exampl~7
This example shows the preparation of a number of BF3/alumina-based
catalyst eomponents. One is made in accord with this invention and three are
10 comparative samples. Each of the samples was then tested in an alkyiation
reaction using rnodet feeds and isobutane and butenes.
All four gamma-alumina samples (LaRoche-Versal GL) were infused with
BF3 in a Cahn balance. Use of a Cahn balance allowed close control of the
temperature at which the alumina contacted the BF3 and turther allowed the
15 weight gain to be measured during the treatment. The four samples were treated
with BF3 resp~ctively at 25- C, 1S0- C, 2~- C, and 350- C. The amount of BF3 in
the samples was 17.4%, 17.3%, 13.7% and 13.6~h (by weight). A sample of each
of the catalyst components was removed and anayzed using 1IB-MAS-NMR. The
results of these analyses are shown in the figures: Figure lA shows the treated
alumina; Figures 1B, 1C, and 1D show the respective data from the 150- C,
250- C, and 350- C treated aluminas. In Figure 1A, there is a pronounced sharp
. ~ peak at about -21.27 ppm (reiative to boric acid) suggesting significant tetragonal
boron contsnt. The other thre~ NMR plots do not show such a sharp peak.
Instead, 1hc data suggest the pres~nce o~ substantial trigonal boron.
The four gamma-alumina samples (LaRoche-Versal GL) were then charged
to a semi-batch reactor having an internal volume of about 500 cc. The reactor
temperature was controliable over the range of -5- C to 40 C. For initial catalyst
treatment, the reactor containing the catalyst was purged with an inert gas and
oooled to about 0 C. About 275 cc of isobutane were added to the reactor. After
a brief degassing, BF3 was added batchwise. Additional infusions of BF3 are
made until the pressure in the reactor no longer ~rops. The BF3 saturation
equilibrium pressure was about 40 psig. The liquid phase concentration of BF3
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W O 92/04977 2 ~ ~ 2 ~ 5 9 PC~rtUS91/06999
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was about 1.5%. ~
A mixture of isobutane/trans-2-butene was fed to the reactor. At the
- completion of the reaction, alkylate was removed and analyzed by gas-liquid
chromatography. The P~ON's were calculated from the gas-liquid chromatography
5 data using the well-known corrslations in Hutson and Logan, ~Es~imate Alky Yleld
and QualityU, Hydrocarbon Processing, Septembsr, 1975, pp. 107-108. The
summary of the experiments and resu~ts is shown in the table below:
F~ed and Oper~ti~nd~ion~
. _ _ _ _ _ .
Sample No. 1 2 3 4
= _ . _ _
Al2O3/~F3 25- 150- 250- 350
treatment
temp. ~ C) _ _ ~ I
__ _ ~ l
catalyst 1.21 1.21 1.21 1.21 l
15 I charge _ ~ _ _ ¦
reaction 0 0 0 0
temp~ (' C)
reaction 30 30 30 30
pressure
` (psig)_
;; iCJolefin 5.98 5.93 5.93 5.93
. ,, _(w/w)
__
' ;'~ i-C4 (t C) 6 68.6 _ 6 _ 6 _~
, feed (cc) 306.4 306.4 306.4 306.4
. . I , _
. ¦ WHSV 14.869 15.559 _ 15.718 17.307
W092/t)4977 r 1~ PCl'/US91/06999
2~2~9 t ~
Produ~ Summ~
I
Sample No. 1 1 1 ~ ¦ 3 ¦ 4
._ . ~
Total 27.63% 19.97% 11.48% 5.62h ¦
alkylate
.
Butene 100.0% 86.15% ~9.09% 67.03%
Conversion
~ 11
CS7 hydro- 1.51% 2.53% 2.55% 0.83%
carbon
11
C8 hydro- 93.33% 87.58% 85.14% 70.5B~
carbon
_ 11
Cg l1 hydro- 0.49,6 3.12'h 6.45% 13.90,6
carbon _ ¦
C,2+ hydro- 4.67% 6.77% 5.~696 14.7~fo
car~on
. !l
: 15 TMP/C8 97-54% 98.27% 96.70h 97.55% ¦
, . _ - 11
Yield (w/w) 1.94 1.40 0.80 0.39 l
~ _ ~
P~ON 99.26 98.09 97.57 92.23 l
. . , .. ~ .. ~
MON 94.88 93.73 93.16 90.07 l
._
(R+ M)/2 97.07 95.g1 95.36 ~1.15 l
., .
2,2,4/2,3,4 0.81 0.54_ _ 0.48 _ 0.33
It is clear from the data that the catalyst component treated with BF3 at the lower
temperature is superior in operation in most practical aspe~ts (conversion, C8
production, alkylate yield, RON, MON, etc.) than the other materials.
, . .
,~ ,
- 30 It should be clear that one having ordinary skill in this art would envision
equivalents to the processes found in the clairns that follow and that these
equivalents would be within the scope and spirit of the claimed invention.
