Note: Descriptions are shown in the official language in which they were submitted.
~933~
Wo 92/07810 PCT~EP91/01951
Description
Process for the preparntion of isopropylnaphthalene
The pre~ent invention relatec to a proce~s for the
preparation of i~opropylnaphthalene by the alkylation of
naphthalene with EV-1 zeolites as catalysts, only ~mall
amounts of diisopropylnaphthalenes being formed.
2-(Mono)isopropylnaphthalene (2-MIPN) i8 a valuable
intermediate for the preparation of 2-naphthol by the
Hock process. 2-Naphthol i8 normally prepared by the
sulfonstion of naphthalene in the 2-position, followed by
saponification of the Na salt of the naphthalenesulfonic
acid in a ~odium hydroxide melt. A larqe ~mount of salts
i8 obtain~d in this proce3s. The Hock procass
substantially avoids this disadvantage.
Apart from 2-MIPN, 2,6-dii~opropylnaphthalene (2t6- DIPN)
is alRo a valuable intermediate for many highly refined
products. Thus it i8 used inter alia as a starting
material for the preparation of naphthalene-2,6-
dicarboxylic acid, 2,6-dihydroxynaphthalene and
6-hydroxynaphthalene-2-carboxylic acid. These compounds
are used as monomers for high-performance polymers.
In practice, the demand for 2-MIPN is considerably
greater than for 2,6-DIPN because of the comparatively
large amount of 2-naphthol produced. It iB therefore
desirable to direct th~ alkylation of naphthalene 80
that, with a high degree of conversion, a large
proportion of ~IPN and a ~mall proportion of DIPN are
formed.
It is known to use a very wide variety of acid catalysts
for the alkylation of naphthalene to MIPN and also DIPN.
When the alkylation iB carried out with Friedel-~rafts
catalysts such as AlClt or BF3, 8alt8 are formed on
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wo 92/07810 - 2 - PCT/EP31J01951
working-up and ~he catalyst t 8 ~d~stroyed. ~oreover,
resi~ous compounds, which imp~de t:he working- up, ~r~
formed in the ~ourse of the reaction. Separation of the
products from the c~talyst is generally expensive. For
5 some tLme ~ ~ttsmptB have therefore been made to replace
catalysts of this ~ype with solid acids.
German patent 2 644 624 de~cxibes a process for the
preparation of 2-MIPN using P2O5/SiO2. Here the
naphthalene has to be used in large excess in ordsr to
prevent the form~tion of polyalkylated products. In
addition, the unreacted naphthalene hAs to be ~eparated
off and recycled into the alkylation. Again, when using
acid-activated montmorillonite (German
Offenlegung~schrift 2 20B 363) or perfluorinated sulfonic
acid resins (US patent 4 288 646), the naphthalene has to
be used in e~cess in order to prevent the formation of
large amounts of polyalkylated products. The low degree
of conversion of the naphthalene in all these processes
represents a considerable di~advantage.
Acidic zeolites have also been used as catalyst6 for the
alkylation of naphthalene. European patent application A-
338 292 describes the reaction of naphthalene with
propylene on dealuminized Y zeolites in the presence of
decahydronaphthalene. At 220C ~nd with a naphthalene
conversion of approx. 50~, the selectivity of this
reaction is between 68 and 75% in re~pect of NIPN,
between 24 and 30% in respect of DIPN and between 1.5 and
3~ in respect of triisopropylnaphthalenes (~IPN). In this
process, the ratio MIPN/(DIPN + TIPN) is very low at 2 to
3.
In other studies, the possibility of ~hape-selective
catalysis is utllized in the preparation of 2-alkyl- and
2,6-dialkyl-naphthalenes. Shape-selective catalysismeans
that the dLmensions of the molecules or transition states
participating in the reaction are of the same order of
~ ~3 J .) .~
wO 92/07810 - 3 - PCT~EP31/Olg51
ma~nitude as those of the cataly~t: pores. The course of
the reaction c~n be influenced b~y ~teric forc~. Thus
.g. in the alkyl~tion of naphthalene with methanol using
zeolites of the ZS~-5 type, the ~ omer~ of low storic
bulk (2-methyl- and 2,6- dLmethyl-naphthalen~) can be
obtained with high selectivity (e.g. D. FrAenkel et ~1.,
J. Catsl. 101 (1986) 273-283, and European patent
application ~A-280 055). However, the naphthalene
conversion is llmited in these proce~es A8 well, becau&e
the diffu~ion of the bulky molecule~ through the zeolite
pores i~ greatly hindered.
The proce~s of European patent applica~ion A-317 907 u6ed
a dealuminized mordenite zeolite for the alkyl8tion of
naphthalene with propylene. A naphthalene converRion of
97.3~ was achieved. The yield of DIPN was 68%, including
50% of 2,6-DIPN. Nothing was said about the yi21d of MIPN
or the composition of thi~ fr~ction. A dealuminiæed
mordenite zeolite i~ also used in the process of
WO 90/03961 for the selective preparation of 2,6-DIPN. It
is stated that, by virtue of this type of zeolite, the
proportion of 2,6-DIPN in the DIPN fraction is greater
than the proportion in thermodynamic equilibrium and that
the ratio 2,6-/2,7- DIPN i8 greater than 1.2. Thus, for
example, with a naphthalene conversion of 27~, the
proportion of 2,6- DIPN i6 ~aid to be 70%, the ratio 2,6-
/2,7-DIPN 3.0 and the ratio MIPN/tDIPN + TIPN) 5.1. If
the conversion increa~es to 78%, the proportion of 2,6-
DIPN drops to 624, the ratio 2,6-/2,7-DIPN to 2.6 and the
ratio MIPN/ (DIPN + TIPN~ to 1.1. No information i8 given
about the composition of the MIPN fraction.
These Example~ &how that mordenite catalysts strongly
~uppreqs the formation of MIPN in favor of DIPN as the
naphthalene conversion increases.
The object of the present invention was to provide a
process for the preparation of MIPN by the alkylation of
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WO 92J07810 - 4 - PCT/EP91/01951
naphthalene which produces the min~lum possible ~mount of
DIPN with a high naphthalene conversion.
Thi~ object is achieved according to the invention by the
use of EU-l ~eolites as catalysts. In this proces~,
monoalkylated product~ ars formed 1with high Relectivity
and dialkylated compounds are only formed in minor
amounts. This process hardly produces any more highly
alkylated compound~ such as TIPN.
The invention now relates to a process for the
preparation of isopropylnaphthalene by the alkylation o
naphthalene with the aid of ca~alysts, wherein the
catalysts used are EU-l zeQlites.
Zeolites are crystalline nluminosilicate~. Si and Al
atoms arP tetrahedrally surrounded by O atoms. The
tetrahedra are linked via common O atoms and form a
crystalline structure through which defined pores and
cavities pass tcf. D.W. Breck, Zeolite Molecular Sieves,
John Wiley & Sons, (1974) p. 29-185). The zeolites of the
EU-l type used according to the invention are
characterized by a typical X-ray diffraction pattern,
which is indicated in European patent ~pplication A-
4~ 226. The pores in this zeolite are bounded by 10 O
atoms and have a width of 0.41 x 0.58 nm. They have
lateral extensions formed by 12 O atoms. These bulges are
0.58 x O.68 nm wide and 0.81 nm deep (N.A. Briscoe et
al., Zeolite6 B, (1988) 74-76).
It is surprising that this precise type of zeolite makes
it possible to achieve the desired high selectivity in
respect of the MIPNs and the low rate of formation of
DIPN, since the use, described in European patent
application A-317 907l of mordenite catalysts with pores
of 0.67 x 0.70 nm, which are larger than those of EU-l
zeolites, as well as the use of zeolites of the ZSM-5
type with somewhat narrower pore~ of 0.52 x O.55 nm and
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WO 92/07810 - 5 - PCT/EP91/01951
O.54 x O.56 nm, result in the formation of ~ far greater
proportion of DIPN.
The different selectivities of thes~ catalysts are
compared in the Examples.
S The EU-l zeolites u~ed according to the invention can be
prepared by known processes of hydrothermal synthesis
(e.g. European patent application A-42 2263. ~lkylated
polymethylenediamine6, preferably N,N,N,N',N',N' hexa-
methyl-l,6-hexamethylenediammoniumbromide(hexamethonium
brsmide), are u~ed as the template. An SiO2~Al2O3 ratio in
the range from 10 to 150 can be obtained by direct
synthesis, but higher SiO2/Al203 ratios can also be
achieved by sub~eguent dealuminization. The aluminum
content can be reduced in a variety of ways here. Some
methods are described e.g. in J. Scherzer, Catalytic
Materials, Relationship between Structure and Reac~ivity,
ACS Symp. Ser. 248 (1984) 175-200. EU-1 zeolites with
SiO2/Al2O3 ratios of between 15 and 200, preferably of
between 20 and 100, are particularly ~uitable for the
process according to the invention.
After crystallization, the zeolite is filtered off,
washed, dried and then calcined in an oxidizing
atmosphere, preferably in air, in order to remove the
organic template from the pore~.
To convert the zeclite to a catalytically active form,
any Nat ion~ pre3ent are exchanged by ion exchange with
divalent or trivalent ions of the alkaline earth metals
or rare earth metals of atomic number 57 to 71, or with
ammonium ion~ or protons. Ion exchange with NH~t or H+ iB
particularly preferred. It i8 convenient here if at lea~t
50%, preferably at least 90%, of the lattice charges are
compensated by ~aid other ions. The zeolite i8 then
converted to the catalytically active form by dehydration
tand deammoniation in the case of NH4t forms) at 200 to
2~3 '`3
~O 92/07810 - 6 - PCT/EP91/01951
800~C, preferably at 40U and 550~C.
For the use according to the invention, the zeolites can
advantageously be converted to ~ ~uitable applicatlon
form, e.g. ~trand~, with the aid of binders. P~rticularly
~uitable binders ~re the oxides, hydroxides or
hydroxychlorides o aluminum and the oxides of silicon,
titanium and zirconium, as well a~ clay materials.
The alkyla~ion reaction can be carried out in the ga~
phase or, preferably, in the liquid phase. Example~ of
alkylating agent~ which can be used are i-propyl bromide
and chloride, propylene and i-propancl. In the ga~ phase
reaction, it is preferable to react naphthalene with
propylene or i-propanol. When the alkylation is carried
out in the liquid phase, it is preferable to use
propylene. ~he reaction temperature i8 conveniently
between about 100 and 500C, preferably between about 150
and 300C. An elevated pressure favor~ the course of the
alkylation, especially if the alkylating agent i6
propylene. ~he reaction can be carried out at reduced
pressure, at atmospheric pressur~ or at an elevated
pressure, e.g. of up to about 100 bar, preferably between
about 2 and 20 bar.
The alkylation in the liquid phase can be carried out in
any suitable apparatus, most 8imply in a stirred tank,
with pulverulent catalyst suspended in molten
naphthalene. The alkylating agent is then passed through
the suspension or forced in under pressure up to the
desired value, at the reaction temperature. The reaction
is preferably carried out without a ~olvent, but solvents
which are inert towards the reactants and catalysts, such
as higher-boiling paraffins or naphthenes, may also be
present. Inert gases such as nitrogen can also be used to
attain the reaction pressure.
The process can be carried out continuously or batchwise.
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wO 92/07810 - 7 - PCT/EP91~01951
In the batch procedure, it i8 favorable to use about O.S
to 50% by weight of catalyst, preferably about 1 to lO~
by weight, ba~ed on the weight of naphthalene u~ed. The
reaction time can be between about half an hour ~nd
several day~, especially between 2 and 10 h, depending on
the reaction condition~ and th~ deEIired conver ion. When
the reaction i~ complete, the zeolite c~n ea~ily be
6eparated from the reaction mixtur~, e.g. by filtration.
To carry out the reaction in the gas phase, it i8
possible in principle to u~e any apparatus sui~able for
gas phase reactions. A fixed bed continuou~-flow reactor
is ~echnicslly the ~imple~t to operate. The cataly~t can
be introduced into the reactor in the form of pellet~,
which can be prepared by compressing the ~eolite on its
own or together with a binder such a~ Al203 or SiO2. The
naphthalene can be metered into the reactor in the molten
state or dis601ved in an inert 601vent and vaporized
upstream of the catalyst bed, or can already be in the
gaseous state when it i~ introduced into the reactor.
i-Propanol can be metered in the ~ame way as naphthalene.
Propylene i8 introduced in the gaseou state. The
reactants can be used on their own or mixed with a gas
which is inert towards the reaction, such as hydrogen or
nitrogen. The reaction products are conden~ed after
leaving the reactor.
The molar ratio of naphthalene to alkylatin~ agent i~
conveniently in the range from about 0.1 to 10,
preferably from about 0.5 to 2.
The re~idence time of the reactants i8 generally between
about O.OS and 20 B, preferably between 1 and 10 B . The
loading (LHSV = liquid hourly ~pace velocity = ml of
charge per ml of cataly~t volume and per hour~ can
preferably be %et in the range from 0.1 to 5 h-1, the
range from 0.5 to 2 h~l being particularly favorable.
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WO 92/07810 - 8 - PCT~EPgl/01951
The catalyst r~t~ins it~ activity over ~ long period and
can be used ~everal tLme~ for the reaction. If it iB
deactivated, it can be regenerated by calcin~tion in an
oxidizin~ stmosphere, preferably in air, at about 350 to
800JC, preferably at about 500 to 600~C.
The product mixture can initially be separated by
distillation into unreacted naphthalene, MIPN, DIPN and
TIPN. If desired, 2-MIPN can be separated from the MIPN
fraction by crystallization, if ppropriate from a
solvent ~uch as methanol or i-prop~nol (see e.g. ~erm~n
Offenlegungsschrift 2 517 591). The filtrate enriched in
l-MIPN can be reconverted to R mixture rich in 2- MIPN by
isomerization on various zeolites (see e.g. US pstent
4 026 959). 2,6-DIPN can similarly be separated from the
DIPN fraction by crystallization (~ee e.g. European
patent 216 009). An adsorptive separation is described
e.g. in Japanese patent application 01 199 921. Together
with naphthalene, the rest of the DIPN fraction,
substantially freed of 2,6-DIPN, can be reconverted to
MIPN by transalkylation.
The crude 2-MIPN and 2,6-DIPN can be further purified to
the desired degree by conventional working-up processes.
Examples
The EU-l zeolites used were ~ynthesized with different
SiO2/Al2O3 ratios according to instructions from th~
literature (European patent 42 226, ~S patent 4 537 754,
G.W. Dodwell et al., Zeolit~s 5 (1985) 153-157~. All
zeolites are used in the proton form (ion exchange with
NH4NO3 solution and subsequent calcination).
i and 2) The ~xample6 and the Comparative Examples C1 to
C3 were carried out in a ~tirred tank. Before the
reaction, the zeolite was dried for 1 h at 300~C and then
WO 92/07810 - 9 - PCT/EP31/01951
~u~pended in powder form in 128 g of molten naphthalene.
Propylene was passed through the suspension at 6.5 l/h
(or ~t 12 l~h in Example 2) a~ atmo~pheric pres~ure. The
reaction temperature wz~ 200C. The experimental results
are collated in Table 1.
T~ble l
Exa~ple Cl C2 C3 1 2
Zeoli~e ZSM-5 MORDENITE EU-l ~U-1
Naphthalene conversion, ~olX23 22 76 23 75
S~lectivities, molX
MIPN 88 89 54 95 62
DIPN lO 11 44 5 32
TIPN 2 0 2 0 6
MIPN/(DIPN+TIPN)7.3 8.1 1.219.0 1.6
A comparison of C1, C2 and Example 1 shows that the
selectivity with which MIPN i8 formed i8 greatly
increased by the u~e of EU-l zeolites when the
naphthalene conversions are not too high; the results are
also markedly improved for high conversion~ (comparison
of C3 and Example 2).
3 to 5) The Example~ and the Comparative Example~ C4 to
C7 were c~rrled out in ~ fixed bed continuou~-flow
reactor at atmospheric preR~ure. The cataly~t was used in
the form of ~trand~. EU-l was compre~sed with 21% by
weigh~ of SiO2 8i; a binder and mordenite with 4û% of
Al2O3. ZSM-5 wa~ compre~ed to tablets without a binder.
Naphthalene was metered into the reactor in the molten
state. Propylene wa used in twice the molar amount.
After leaving the re~ctor, the reaction products were
conden~ed at certain time intervals and analyzed by ga8
chromatography. The re~ults (where T = 280C,
LHSV - 0 . 5 h-l (ba~ed on naphthalene), catalyst volume
= 25 ml, quantity ratio of naphthalene to propylene
= 1:2) are collated in Table 2.
3 ~
WO 92/07810 - 10 - PCT/EP91/01951
Tabl~ 2
Ex~ple 3 4 5 C4 C5 C6 C7
Zeolit~ EU-l MORDE~ITE ZSM-5
Time, h 1.1 2.1 5.11.23.1 7.1 2.1
S Nsphth~le~e conversion,
molX 39 30 28 36 23 9 3
Selectivities, molX
MIPN 78 83 a4 64 71 85 53
DIPN 18 15 14 33 27 15 35
TIPN 2 1 1 3 2 0 12
MIPN/(DIPN+TIPN) 3.95.25.6 1.8 2.4 5.7 1.1
A comparison of Example~ 3 to 5 with Comparstive Examples
C4 to C7 ~how~ that markedly higher naphthalene
conversions are ~chieved after the ~ame times when using
EU-l zeolites, this type of zeolite also being markedly
superior in respect of the selectivity with which ~IPN is
formed. ~oreover, the EU-l zeolites exhibit a lower
deactivation after longer period~.
