U.S. patent application number 09/991831 was filed with the patent office on 2002-05-16 for production of phenol using reactive distillation.
Invention is credited to Levin, Doron, Santiesteban, Jose G..
Application Number | 20020058845 09/991831 |
Document ID | / |
Family ID | 23859932 |
Filed Date | 2002-05-16 |
United States Patent
Application |
20020058845 |
Kind Code |
A1 |
Levin, Doron ; et
al. |
May 16, 2002 |
Production of phenol using reactive distillation
Abstract
A process for producing phenol and acetone from cumene
hydroperoxide comprises: i) introducing a cumene hydroperoxide feed
into a reactive distillation column comprising at its upper portion
a distillation column and at its lower portion a catalyst bed, at a
point above said catalyst bed; ii) mixing a diluting portion of
acetone with said cumene hydroperoxide to provide a diluted cumene
hydroperoxide; iii) directing said diluted cumene hydroperoxide
through said catalyst bed under conditions sufficient to effect the
exothermic decomposition of said cumene hydroperoxide to a product
comprising a heavy fraction comprising phenol and a vaporized light
fraction comprising acetone; iv) withdrawing said heavy fraction as
bottoms from said column; v) flowing said vaporized light fraction
upwards through the catalyst bed and at least a portion of the
reactive distillation column; vi) condensing said light fraction to
provide at least a portion of said diluting portion of acetone for
subsequent mixing with said cumene hydroperoxide feed; vii)
optionally withdrawing a portion of said light fraction as overhead
from said column; and viii) repeating steps i) through vii). An
apparatus for carrying out the process is also provided.
Inventors: |
Levin, Doron; (Bala Cynwyd,
PA) ; Santiesteban, Jose G.; (West Chester,
PA) |
Correspondence
Address: |
ExxonMobil Chemical Company
P.O. Box 2149
Baytown
TX
77522
US
|
Family ID: |
23859932 |
Appl. No.: |
09/991831 |
Filed: |
November 14, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09991831 |
Nov 14, 2001 |
|
|
|
09468465 |
Dec 21, 1999 |
|
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|
Current U.S.
Class: |
568/385 ;
568/768 |
Current CPC
Class: |
Y02P 20/10 20151101;
Y10S 203/06 20130101; C07C 37/08 20130101; C07C 45/53 20130101;
Y02P 20/127 20151101; C07C 45/53 20130101; C07C 49/08 20130101;
C07C 37/08 20130101; C07C 39/04 20130101 |
Class at
Publication: |
568/385 ;
568/768 |
International
Class: |
C07C 045/53; C07C
037/08 |
Claims
What is claimed is:
1. A process for producing phenol and acetone from cumene
hydroperoxide, which comprises: i) introducing a cumene
hydroperoxide feed into a reactive distillation column comprising
at its upper portion a distillation column and at its lower portion
a catalyst bed, at a point above or at an upper portion of said
catalyst bed; ii) mixing a diluting portion of acetone with said
cumene hydroperoxide to provide a diluted cumene hydroperoxide;
iii) directing said diluted cumene hydroperoxide through said
catalyst bed under conditions sufficient to effect the exothermic
decomposition of said cumene hydroperoxide to a product comprising
a heavy fraction comprising phenol and a vaporized light fraction
comprising acetone; iv) withdrawing said heavy fraction as bottoms
from said column; v) flowing said vaporized light fraction upwards
through the catalyst bed and at least a portion of the reactive
distillation column; vi) condensing said light fraction to provide
at least a portion of said diluting portion of acetone for
subsequent mixing with said cumene hydroperoxide feed; vii)
optionally withdrawing a portion of said light fraction as overhead
from said column; and viii) repeating steps i) through vii).
2. The process of claim 1 wherein steps v) and vi) are used to
control dilution of the cumene hydroperoxide with acetone.
3. The process of claim 2 which comprises setting a reflux rate of
acetone through said column to control dilution of cumene
hydroperoxide feed.
4. The process of claim 1 wherein a flow of diluted cumene
hydroperoxide through the reactor is maintained at a rate
sufficient to keep the catalyst bed wetted, thereby maintaining
catalyst temperature at or near the boiling point of the
liquid.
5. The process of claim 1 wherein said diluting portion of acetone
is added to at least one of: 1) the upper portion of the
distillation column, 2) the lower portion of the distillation
column, upstream of said catalyst bed, and 3) the cumene
hydroperoxide feed prior to its introduction to said distillation
column.
6. The process of claim 1 wherein said diluting portion of acetone
is added to the upper portion of the distillation column.
7. The process of claim 1 wherein said diluting portion of acetone
is added to the lower portion of the distillation column.
8. The process of claim 1 wherein said diluting portion of acetone
is added to the cumene hydroperoxide feed prior to its introduction
to said distillation column.
9. The process of claim 1 wherein said diluting portion of acetone
is added directly at one or more locations to the catalyst bed in
an amount sufficient to reduce formation of heavy compounds having
a normal boiling point greater than 182.degree. C.
10. The process of claim 9 wherein said diluting portion of acetone
is added is added to said catalyst bed in amounts sufficient to
maintain the catalyst bed at a temperature at or near the boiling
point of the reactant liquid to provide isothermal operation.
11. The process of claim 1 wherein said catalyst bed comprises a
solid acid heterogeneous catalyst.
12. The process of claim 1 wherein said conditions sufficient to
effect the exothermic decomposition of said cumene hydroperoxide
comprise a temperature of 20 to 150.degree. C. and a pressure of
atmospheric to 1000 psig.
13. The process of claim 1 wherein said conditions sufficient to
effect the exothermic decomposition of said cumene hydroperoxide
comprise a temperature of 40 to 120.degree. C. and a pressure of
atmospheric to 400 psig.
14. An apparatus for preparing phenol from cumene hydroperoxide
which comprises a) a reactive distillation column comprising at its
upper portion a distillation column and its lower portion a
catalyst bed; b) a lower outlet downstream of the catalyst bed for
removing high boiling bottom products comprising phenol; c) an
inlet at or near the bottom of said distillation column for
introducing cumene hydroperoxide feed at a point upstream of said
catalyst bed; d) an upper outlet for removing low boiling overhead
products comprising acetone; e) a heat exchanger for cooling said
overhead products; f) an overhead products receiver for receiving
cooled overhead products from said heat exchanger, having an outlet
from which said overhead products are collected and/or returned to
said distillation column; and g) overhead products inlet at an
upper portion of said distillation column for introducing overhead
products reflux from said receiver.
15. The apparatus of claim 14 which further comprises an element
selected from the group consisting of h) an overhead products inlet
at a lower portion of said distillation column for introducing
overhead products from said receiver to said distillation column at
or near said inlet for introducing cumene hydroperoxide; i) an
overhead products line which recycles overhead products to the
cumene hydroperoxide feed upstream of said inlet for introducing
cumene hydroperoxide; and j) an overhead products line which
recycles overhead products to one or more portions of the catalyst
bed.
16. The apparatus of claim 14 which further comprises an overhead
products inlet at a lower portion of said distillation column for
introducing overhead products from said receiver to said
distillation column at or near said inlet for introducing cumene
hydroperoxide.
17. The apparatus of claim 14 which further comprises an overhead
products line which recycles overhead products to the cumene
hydroperoxide feed upstream of said inlet for introducing cumene
hydroperoxide.
18. The apparatus of claim 14 which further comprises an overhead
products line which recycles overhead products to one or more
portions of the catalyst bed.
19. The apparatus of claim 14 which further comprises a stripping
section located beneath said catalyst bed.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to the production of phenol and more
particularly to a process for producing phenol and acetone from
cumene hydroperoxide (CHP) using reactive distillation.
[0003] 2. Description of the Prior Art
[0004] Phenol is an important organic chemical with a wide variety
of industrial uses. It is used, for example, in the production of
phenolic resins, bisphenol-A and caprolactam. A number of processes
are currently in use for the production of phenol but the single
process providing the largest proportion of the total production
capacity is the cumene process which now accounts for over three
quarters of the total U.S. production. The basic reaction involved
in this process is the cleavage of cumene hydroperoxide into phenol
and acetone:
C.sub.6H.sub.5C(CH.sub.3).sub.2OOH.dbd.C.sub.6H.sub.5OH+(CH.sub.3).sub.2CO
[0005] The reaction takes place under acid conditions with the
yield of both phenol and acetone generally being 40 percent or
more.
[0006] On an industrial scale, the cumene hydroperoxide is usually
treated with dilute sulphuric acid (0.5 to 25 percent
concentration) at a temperature of about 50.degree. to 70.degree.
C. After the cleavage is complete, the reaction mixture is
separated and the oil layer distilled to obtain the phenol and
acetone together with cumene, alpha-methylstyrene, acetophenone and
tars. The cumene may be recycled for conversion to the
hydroperoxide and subsequent cleavage. The phenol produced in this
way is suitable for use in resins although further purification is
required for a pharmaceutical grade product.
[0007] The heterogeneous cleavage of cumene hydroperoxide (CHP)
over various solid acid catalysts has already been reported. For
example, U.S. Pat. No. 4,490,565 discloses the use of zeolite beta
in the cleavage of cumene hydroperoxide, whereas U.S. Pat. No.
4,490,566 discloses the use of a Constraint Index 1-12 zeolite,
such as ZSM-5, and EP-A-492807 discloses the use of faujasite in
the same process. The use of smectite clays in the acid-catalyzed
decomposition of cumene hydroperoxide is described in U.S. Pat. No.
4,870,217.
[0008] U.S. Pat. No. 4,898,995 discloses a process for the
coproduction of phenol and acetone by reacting cumene hydroperoxide
over a heterogeneous catalyst consisting of either an ion exchange
resin having sulfonic acid functionality or a heteropoly acid, such
as 12-tungstophosphoric acid, on an inert support, such as silica,
alumina, titania and zirconia. Such heteropoly acid catalysts are
generally used as their hydrates, and as such are inherently
unstable at temperatures in excess of 350.degree. C.
[0009] Catalytic distillation has been used to produce cumene by
alkylating propylene with benzene. See, J. Shoemaker, et al.,
Cumene by Catalytic Distillation, Hydrocarbon Processing, p. 57,
(June, 1987).
[0010] U.S. Pat. No. 4,935,577 to Huss, Jr., et al. discloses the
use of Lewis acid promoted inorganic oxide catalyst systems for
alkylation and oligomerization processes using catalytic
distillation.
[0011] U.S. Pat. No. 5,055,627 to Smith, Jr., et al. discloses an
alkylation process for preparing cumene from benzene and propylene
in a zeolitic catalyst bed disposed in a distillation column
reactor. The alkylated benzene is withdrawn from the distillation
column reactor at a point below the fixed bed and unreacted organic
aromatic compound may be taken off as an overhead.
[0012] U.S. Pat. No. 5,905,178 to Hildreth discloses a process for
removing alpha-methyl styrene from admixtures with cumene by
hydrogenation using catalytic distillation to selectively
hydrogenate the side chains and produce cumene. The alpha-methyl
styrene is produced as a byproduct in the cumene-phenol
peroxidation process.
[0013] It is an object of the present invention to provide a
process for the production of phenol and acetone using catalytic
distillation. This process would provide a method of reacting
cumene hydroperoxide which would avoid excessive heat buildup and
utilize cumene hydroperoxide's high heat of reaction (60.6
kcal/mol) to separate out low boiling point decomposition products,
such as acetone.
SUMMARY OF THE INVENTION
[0014] The present invention relates to a process for producing
phenol and acetone from cumene hydroperoxide, wherein the process
comprises the steps of:
[0015] i) introducing a cumene hydroperoxide feed into a reactive
distillation column comprising at its upper portion a distillation
column and at its lower portion a catalyst bed, at a point above or
at an upper portion of said catalyst bed;
[0016] ii) mixing a diluting portion of acetone with said cumene
hydroperoxide to provide a diluted cumene hydroperoxide;
[0017] iii) directing said diluted cumene hydroperoxide through
said catalyst bed under conditions sufficient to effect the
exothermic decomposition of said cumene hydroperoxide to a product
comprising a heavy fraction comprising and a vaporized light
fraction comprising acetone;
[0018] iv) withdrawing said heavy fraction as bottoms from said
column;
[0019] v) flowing said vaporized light fraction upwards through the
catalyst bed and at least a portion of the reactive distillation
column;
[0020] vi) condensing said light fraction to provide at least a
portion of said diluting portion of acetone for subsequent mixing
with said cumene hydroperoxide feed;
[0021] vii) optionally withdrawing a portion of said light fraction
as overhead from said column; and
[0022] viii) repeating steps i) through vii).
[0023] Steps v) and vi) can be used to control dilution of the
cumene hydroperoxide feed, e.g., by setting the reflux rate of
acetone through said column. The liquid flow of the diluted cumene
hydroperoxide through the reactor is preferably maintained at a
rate sufficient to keep the catalyst bed wetted, thereby
maintaining catalyst temperature at or near the boiling point of
the liquid to provide isothermal operation of the process. Given
that step vii) is optional, the presently claimed process includes
operation under conditions of total reflux with all overhead
product being returned to the column.
[0024] The diluting portion of acetone can be added to at least one
of: 1) the upper portion of the distillation column, 2) the lower
portion of the distillation column, upstream of said catalyst bed,
e.g., at the CHP feed tray, and 3) the cumene hydroperoxide feed
prior to its introduction to said distillation column. Recovered
overhead which contains acetone can also be added directly at one
or more locations to the catalyst bed in amounts sufficient to
reduce formation of heavy compounds, i.e., compounds with normal
boiling points greater than 182.degree. C., e.g., dimers of
.alpha.-methylstyrene (AMS). Such interstage injection of acetone
diluent can be used to assist in maintaining the catalyst bed at a
temperature at or near the boiling point of the reactant liquid to
provide preferred isothermal operation, while eliminating reactor
"hot spots."
[0025] In another aspect, the present invention relates to an
apparatus for preparing phenol from cumene hydroperoxide which
comprises:
[0026] a) a reactive distillation column comprising at its upper
portion a distillation column and its lower portion a catalyst
bed;
[0027] b) a lower outlet downstream of the catalyst bed for
removing high boiling bottom products comprising phenol;
[0028] c) an inlet at or near the bottom of said distillation
column for introducing cumene hydroperoxide feed at a point
upstream of said catalyst bed;
[0029] d) an upper outlet for removing low boiling overhead
products comprising acetone;
[0030] e) a heat exchanger upstream of said upper outlet for
cooling said overhead products;
[0031] f) an overhead products receiver upstream of said heat
exchanger having an outlet from which said overhead products are
collected and/or returned to said distillation column; and
[0032] g) overhead products inlet at an upper portion of said
distillation column for introducing overhead products reflux from
said receiver.
[0033] The apparatus can further comprise an element selected from
the group consisting of
[0034] h) an overhead products inlet at a lower portion of said
distillation column for introducing overhead products from said
receiver to said distillation column at or near said inlet for
introducing cumene hydroperoxide;
[0035] i) an overhead products line which recycles overhead
products to the cumene hydroperoxide feed upstream of said inlet
for introducing cumene hydroperoxide; and
[0036] j) an overhead products line which recycles overhead
products to one or more portions of the catalyst bed.
[0037] The process and apparatus of the invention can achieve at or
near 100% conversion of cumene hydroperoxide at long on-stream
times with high selectivity to phenol and acetone and with
extremely low coproduction of high boiling impurities such as
4-cumylphenol, and 2,4-diphenyl4-methyl-1-pentene. Moreover, the
present invention allows efficient use of the heat of reaction
evolved from decomposition of cumene hydroperoxide to effect
separation of lower boiling products, e.g, acetone, from the
reaction product mixture. Such an arrangement minimizes reboiler
use, reducing energy costs, while providing higher yields, good
product purity and lower capital investment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 depicts a flow diagram for an embodiment of the
present invention wherein reflux acetone is introduced at the top
of the distillation column.
[0039] FIG. 2 depicts a flow diagram for an embodiment of the
present invention wherein acetone is introduced at the top of the
distillation column, directly above the catalyst bed, and/or
recycled into the cumene hydroperoxide feed.
[0040] FIG. 3 depicts a flow diagram for an embodiment of the
present invention wherein acetone is introduced at the top of the
distillation column, directly above the catalyst bed, and/or into
the catalyst bed.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0041] In catalytic distillation. a reaction zone containing
catalyst is fitted into a fractionation tower equipped with an
overhead condenser, reflux pump, reboiler, overhead receiver and
control instrumentation. Feed components are introduced above the
catalyst bed. Products are continuously removed from the reaction
zone by the distillation process.
[0042] Catalytic distillation is suitable only for chemical
reactions where the distillation of reaction components occurs in
the same temperature range as the reaction. Thus, operation above
the critical point can be a limitation, and the presence of
azeotropes or close boiling components may cause difficulties.
[0043] Inasmuch as distillation columns are typically operated at
higher liquid and vapor flow rates than conventional reactors, the
reduced residence time in the reactive section of the column of the
present invention will minimize the formation of byproducts. This
is especially advantageous in the case of CHP decomposition as the
dehydration of 2-phenyl-2-propanol leads to the formation of
.alpha.-methylstyrene (AMS), a reactive intermediate that could
undergo further reactions such as dimerization, oligomerization,
and coke formation. Minimizing the formation of heavy compounds
will extend catalyst life if a heterogeneous catalyst is employed
for the reactive section of the column.
[0044] The preferred conditions for the decomposition reaction
include temperature and pressure ranges that are suitable for use
in a distillation column. Due to the high heat of reaction,
decomposition preferably takes place under dilute CHP
concentrations, of the order of less than 50 wt. %, preferably 0.1
to 25 wt. %, and most preferably 0.5 to 5 wt. %, e.g., about 3 wt.
% CHP. The feed to the tower can range from 25 to 95 wt. %,
preferably 75 to 85 wt. %, e.g., 80 wt. % CHP, and needs to be
further diluted, preferably by acetone, to the above-noted levels.
Control of the dilution level can be achieved by setting the reflux
rate through the tower, or directly adding the recycled overhead
containing acetone to the cumene hydroperoxide feed.
[0045] Table 1 lists the normal boiling points for the major
components involved in the decomposition of cumene hydroperoxide.
Acetone has a significantly lower boiling point than all the other
major components, thereby facilitating its separation in a reactive
distillation column. Other low boiling components may also be
present in the column, e.g., methanol, acetaldehyde, and
benzene.
1 TABLE 1 Component Normal Boiling Point (.degree. C.) Acetone 56.3
Cumene 152.4 .alpha.-Methylstyrene 165.5 Phenol 181.8
2-Phenyl-2-Propanol 192.6 Acetophenone 202.0
[0046] The catalyst employed can be either a homogeneous or
heterogeneous catalyst. Suitable homogeneous catalyst systems can
employ a suitable catalyst such as dilute (0.01 to 5 percent
concentration) sulfuric acid. Other acids such as perchloric acid,
phosphoric acid, p-toluenesulfonic acid, and sulfur dioxide are
also effective homogeneous catalysts.
[0047] Suitable heterogeneous catalysts for use in the cleavage of
cumene hydroperoxide include solid acid catalysts such as zeolite
beta, disclosed in U.S. Pat. No. 4,490,565; a Constraint Index 1-12
zeolite, such as ZSM-5, disclosed in U.S. Pat. No. 4,490,566;
faujasite, disclosed in EP-A-492807; smectite clays, described in
U.S. Pat. No. 4,870,217; ion exchange resins having sulfonic acid
functionality or heteropoly acids, such as 12-tungstophosphoric
acid, on an inert support, such as silica, alumina, titania and
zirconia, disclosed in U.S. Pat. No. 4,898,995. Additional
solid-acid catalysts suited for use in the present invention
include those comprising a sulfated transition metal oxide such as
sulfated zirconia together with an oxide of iron or oxides of iron
and manganese as described in U.S. patent application Ser. No.
09/296,852, filed Aug. 22, 1999 (Attomey's Docket No. 10144-1), as
well as those comprising a mixed oxide of cerium and a Group IVB
metal, e.g., zirconium, described in U.S. patent application Ser.
No. 09/366,249, filed Aug. 3, 1999 (Attorney's Docket No.
10173-1.)
[0048] The process of the invention can also use a solid acid
catalyst comprising an oxide of a Group IVB metal modified with an
oxyanion or oxide of a Group VIB metal by calcination of the oxide
species at a temperature of at least 400.degree. C., as disclosed
in U.S. patent application Ser. No. 09/275,749, filed Mar. 25, 1999
(Attorney Docket No. 10135-1). The modification of the Group IVB
metal oxide with the oxyanion of the Group VIB metal imparts acid
functionality to the material. The modification of a Group IVB
metal oxide, particularly, zirconia, with a Group VIB metal
oxyanion, particularly tungstate, is described in U.S. Pat. No.
5,113,034; and in an article by K. Arata and M. Hino in Proceedings
9th International Congress on Catalysis, Volume 4, pages 1727-1735
(1988).
[0049] The large pore crystalline molecular sieves which can be
used in the present invention include those which have pores
sufficiently large to physically absorb 2,2,4-trimethylpentane.
Representative large pore crystalline molecular sieves include, for
example the following zeolites: ZSM-3, ZSM-4, ZSM-12, ZSM-18,
ZSM-20, zeolite Beta, zeolite L, mordenite, faujasite, zeolite Y,
and the rare earth metal-containing forms of the above. For the
purposes of this invention, zeolite Y includes zeolite Y in its as
synthesized form, as well as its variant forms including framework
dealuminated zeolite, e.g., ultrastable Y (USY) described in U.S.
Pat. No. 3,293,192 and LZ-210 described in U.S. Pat. No. 4,503,023,
hereby incorporated by reference. The large pore zeolite selected
for use in the process of this invention generally can possess an
alpha value over a wide range of from less than 1 to over 1000.
"Alpha value", or "alpha number", is a measure of zeolite acidic
functionality and is more fully described together with details of
its measurement in U.S. Pat. No. 4,016,218, J. Catalysis, 6, pp.
278-287 (1966) and J. Catalysis, 61, pp. 390-396 (1980). Zeolites
of low acidity (alpha values of less than about 200) can be
achieved by a variety of techniques including (a) synthesizing a
zeolite with a high silica/alumina ratio, (b) steaming, (c)
steaming followed by dealuminization and (d) substituting framework
aluminum with other species. For example, in the case of steaming,
the zeolite can be exposed to steam at elevated temperatures
ranging from about 500.degree. to about 1200.degree. F. and
preferably from about 750.degree. to about 1000.degree. F. This
treatment can be accomplished in an atmosphere of 100% steam or an
atmosphere consisting of steam and a gas which is substantially
inert to the zeolite. A similar treatment can be accomplished at
lower temperatures using elevated pressure, e.g., at from about
3500 to about 700.degree. F. with from about 10 to about 200
atmospheres. Specific details of several steaming procedures may be
gained from the disclosures of U.S. Pat. Nos. 4,325,994; 4,374,296
and 4,418,235, the contents of which are incorporated by reference
herein. Aside from, or in addition to any of the foregoing
procedures, the surface acidity of the zeolite can be eliminated or
reduced by treatment with bulky reagents as described in U.S. Pat.
No. 4,520,221, the contents of which are incorporated by reference
herein.
[0050] Other large pore crystalline molecular sieves which can be
used in the present invention include pillared silicates and/or
clays; aluminophosphates, e.g., ALPO-5, VPI-5;
silicoaluminophosphates, e.g., SAPO-5, SAPO-37, SAPO-31, SAPO40,
SAPO41; and other metal aluminophosphates. These are variously
described in U.S. Pat. Nos. 4,440,871; 4,554,143; 4,567,029;
4,666,875 and 4,742,033, incorporated herein by reference.
[0051] The particular class of macroreticular acid cation exchange
resins useful as catalysts in the present invention are
characterized by substantial porosity, high surface area and a low
surface acid concentration, generally less than about 0.5
milliequivalents of hydrogen ion per square meter surface area. The
cation exchange resin can contain a small amount of water,
generally between 0.5 and 20 percent by weight. The macroreticular
resins utilized in the process of this invention are characterized
by the presence of acid functional groups and a structure having a
high degree of true porosity while possessing rigidity and being
subject to minimum volume change when immersed or removed from
solvents or solutions.
[0052] The macroreticular acid ion exchange resin used is typified
by the presence of sulfonic acid groups, e.g., the sulfonated
styrene-divinylbenzene copolymer exchange resins such as those
commercially available as Amberlyst-15, Amberlyst XN-1005,
Amberlyst XN-1010, Amberlyst XN-1011, Amberlyst XN-1008 and
Amberlite 200.
[0053] Perfluorinated ion-exchange polymers, or porous
microcomposites comprising perfluorinated ion-exchange polymer
containing sulfonic acid and/or carboxylic acid groups dispersed
within a network of a metal oxide such as silica, e.g. Nafion.RTM.,
are also useful as catalysts in the present invention.
[0054] The solid catalyst can be shaped into a wide variety of
particle sizes. The particles can be in the form of a powder, a
granule, or a molded product, such as an extrudate. In cases where
the catalyst is molded, such as by extrusion, the catalyst can be
extruded before drying, or partially dried and then extruded. The
present catalyst may be extruded by itself, or it may be composited
with a matrix material to form the finished form of the catalyst
and for this purpose conventional matrix materials such as alumina,
silica-alumina and silica are suitable with preference given to
silica as a non-acidic binder. Other binder materials may be used,
for example, titania, zirconia and other metal oxides or clays. The
active catalyst may be composited with the matrix in amounts from
80:20 to 20:80 by weight, e.g., from 80:20 to 50:50 active
catalyst:matrix. Compositing may be done by conventional means
including mulling the materials together followed by extrusion or
pelletizing into the desired finished catalyst particles.
[0055] The cleavage reaction of the invention is effected by
contacting the cumene hydroperoxide with the solid oxide catalyst
described above in the liquid phase at a temperature of 20 to
150.degree. C., preferably 40 to 120.degree. C., and a pressure of
-10 to 1000 psig, preferably atmospheric to 400 psig. To effect the
contacting of the cumene hydroperoxide, the catalyst may be
contained in a stationary bed, and the contacting operation takes
place continuously.
[0056] The liquid hourly space velocity (LHSV) based on cumene
hydroperoxide is within the range of 0.1 to 100 hr.sup.-1,
preferably 1 to 50 hr.sup.-1. The cumene hydroperoxide is
preferably diluted in an organic solvent inert to the cleavage
reaction, such as benzene, toluene, cumene and most preferably
acetone. Control of the dilution level can be achieved by setting
the reflux rate through the tower, or directly adding the recycled
overhead containing the solvent to the cumene hydroperoxide feed.
The use of a solvent is preferred so as to assist in dissipating
the heat of reaction (about 60 kcal/mol).
[0057] The packing which may be used in the distillation column
employed in the present invention is selected as a function of the
efficiency necessary for the distillation operation. The packing
can be selected from packings which are well known to the skilled
person, such as solids in the form of rings, poly-lobed extrudates
or saddle packing. Non-limiting examples of packing are Raschig
rings, Pall rings, Intos rings, Berl saddle packing, Novalox saddle
packing and Intalox saddle packing. The packing can also be
selected from structured packings, for example, FLEXIPAC
(registered trademark) sold by Koch, or SULZER CHEMTECH or SULZER
(registered trademarks) sold by Sulzer.
[0058] A distributing tray which may be used in the process of the
present invention is a simple tray which allows the upward passage
of vapor and collection. then overflow of liquid, as in any
distributing tray which is known to the skilled person, in
particular if the major portion of the distillation zone to which
it belongs is composed of packing. When a distillation tray is used
in accordance with the present invention, the tray can be selected
from distillation trays which are known to the skilled person, in
particular perforated trays, bubble cap trays, or valve trays.
[0059] The operation of a catalytic distillation column according
to the present invention leads to a distribution of components
throughout the column and catalyst bed. The concentration of
various components may affect the optimal performance of the
catalyst by retarding desired reactions and promoting undesired
ones. To achieve optimal operation of the catalyst bed, the bed can
be located at a position within the column where the component
concentrations are optimal. This may lead to the presence of a
separate distillation section acting as a stripper positioned below
the catalyst bed.
[0060] The invention will now be more particularly described with
reference to the following Examples.
EXAMPLE 1
[0061] In the process configuration of FIG. 1, phenol and acetone
are produced from cumene hydroperoxide in a reactive distillation
column 100. A cumene hydroperoxide-containing feed line 110
containing about 80 wt. % CHP introduces feed through inlet 120 at
a point above catalyst bed 130 where it is mixed with a diluting
portion of acetone derived from column overhead to provide a dilute
cumene hydroperoxide mixture which passes through the catalyst bed
130 under cumene hydroperoxide decomposition conditions including a
temperature of about 50 to 90.degree. C., a pressure of 0 to 10
psig, and an LHSV of 0.3 to 5 hr.sup.-1 to provide a product
comprising phenol and acetone. The catalyst bed is an unstructured
packed bed of solid catalyst. The catalyst is in the form of
pellets, typically greater than {fraction (1/24)}" diameter, such
that the catalyst bed void volume allows for liquid flow down the
bed, and vapor flow up the bed.
[0062] The catalyst is prepared as follows: five hundred parts of
ZrOCl.sub.2.8H.sub.2O are dissolved with stirring in 3.0 liters of
distilled water. To this solution is added 7.6 parts of
FeSO.sub.4.7H.sub.2O. Another solution containing 260 parts of
concentrated NH.sub.4OH, 54 parts of
(NH.sub.4).sub.6H.sub.2W.sub.12O.sub- .40.xH.sub.2O and 2940 parts
of distilled water was prepared. Both solutions were heated to
60.degree. C. and the heated solutions were combined at a rate of
50 parts/min using nozzle mixing. The pH of the final composite was
adjusted to approximately 9 by the addition of concentrated
ammonium hydroxide. This slurry was then put in polypropylene
bottles and placed in a steambox (100.degree. C.) for 72 hours. The
product formed was recovered by filtration, washed with excess
water, and dried overnight at 85.degree. C. The dried product was
calcined to 800.degree. C. in flowing air for 3 hours, and then
formed into pellets. The catalyst pellets were thereafter added to
the catalyst bed.
[0063] Phenol and other heavies formed pass downwardly through the
catalyst bed and are withdrawn from the reactive distillation
column through lower outlet 140 and are sent for recovery in the
distillation section of the plant (not shown). Overheads containing
acetone pass upwardly through the column and through upper outlet
150 and thence to a heat exchanger such as condenser 160 and
thereafter to overheads receiver 170. The acetone-containing
overhead can be withdrawn from the receiver through line 180 or
recycled as reflux to an upper portion of the distillation column
190. Dilution of cumene hydroperoxide feed with acetone is
controlled by varying the amount of acetone recycled to the
distillation column, i.e., setting the reflux rate through the
tower. The compositions of the proposed feed and estimated product
compositions are provided below in TABLE 2.
2 TABLE 2 Overhead Bottoms Feed Product Product Acetone 0.00 99.57
8.43 Mesityl Oxide 0.00 0.00 0.00 Cumene 7.70 0.00 10.26 Phenol
0.17 0.00 67.67 .alpha.-Methyl Styrene 0.27 0.00 9.47 Acetophenone
2.19 0.00 2.92 2-Phenyl-2-Propanol 7.87 0.00 0.00 Cumene
Hydroperoxide 81.80 0.00 0.00 Water 0.00 0.43 1.25
EXAMPLE 2
[0064] In the process configuration of FIG. 2, phenol and acetone
are produced from cumene hydroperoxide in a reactive distillation
column 200. A cumene hydroperoxide-containing feed line 210
containing about 80 wt. % CHP introduces feed through inlet 220 at
a point above catalyst bed 230 where it is mixed with a diluting
portion of acetone derived from column overhead to provide a dilute
cumene hydroperoxide mixture which passes through the catalyst bed
230 under cumene hydroperoxide decomposition conditions including a
temperature of about 50 to 90.degree. C., a pressure of 0 to 10
psig, and an LHSV of 0.3 to 5 hr.sup.-1 to provide a product
comprising phenol and acetone. The catalyst bed is an unstructured
packed bed of solid catalyst as described in Example 1. Phenol and
other heavies formed pass downwardly through the catalyst bed and
are withdrawn from the reactive distillation column through lower
outlet 240 and are sent for recovery in the distillation section of
the plant (not shown). Overheads containing acetone pass upwardly
through the column and through upper outlet 250 and thence to a
heat exchanger such as condenser 260 and thereafter to overheads
receiver 270. The acetone-containing overhead can be withdrawn from
the receiver through line 280 or recycled as reflux to an upper
portion of the distillation column through line 290 or through line
292 to a lower portion of the distillation column (at the CHP feed
tray level). Alternatively, or in addition, the recycled overhead
is directed through line 294 to the cumene hydroperoxide feed 210
as a way to effect dilution as required. Thus, dilution of cumene
hydroperoxide feed with acetone is controlled by varying the amount
of acetone recycled to the distillation column, i.e., setting the
reflux rate through the tower, at upper and/or lower portions of
the distillation column, or added directly to the CHP feed. The
compositions of the proposed feed and estimated product
compositions are provided below in TABLE 3.
3 TABLE 3 Overhead Bottoms Feed Product Product Acetone 0.00 99.68
27.61 Mesityl Oxide 0.00 0.00 0.00 Cumene 7.70 0.00 8.11 Phenol
0.17 0.00 53.42 .alpha.-Methyl Styrene 0.27 0.00 7.47 Acetophenone
2.19 0.00 2.31 2-Phenyl-2-Propanol 7.87 0.00 0.00 Cumene
Hydroperoxide 81.80 0.00 0.00 Water 0.00 0.32 1.08
EXAMPLE 3
[0065] In the process configuration of FIG. 3, phenol and acetone
are produced from cumene hydroperoxide in a reactive distillation
column 300. A cumene hydroperoxide-containing feed line 310
containing about 80 wt. % CHP introduces feed through inlet 320 at
a point above catalyst bed 330 where it is mixed with a diluting
portion of acetone derived from column overhead to provide a dilute
3 wt. % cumene hydroperoxide mixture which passes through the
catalyst bed 330 under cumene hydroperoxide decomposition
conditions including a temperature of about 50 to 90.degree. C., a
pressure of 0 to 10 psig, and an LHSV of 0.3 to 5 hr.sup.-1 to
provide a product comprising phenol and acetone. The catalyst bed
is an unstructured packed bed of solid catalyst as described in
Example 1. Phenol and other heavies formed pass downwardly through
the catalyst bed and are withdrawn from the reactive distillation
column through lower outlet 340 and are sent for recovery in the
distillation section of the plant (not shown). Overheads containing
acetone pass upwardly through the column and through upper outlet
350 and thence to a heat exchanger such as condenser 360 and
thereafter to overheads receiver 370. The acetone-containing
overhead can be withdrawn from the receiver through line 380 or
recycled as reflux to an upper portion of the distillation column
through line 390 or through line 392 to a lower portion of the
distillation column (at the CHP feed tray level). Alternatively, or
in addition, the recycled overhead can be directed through line 396
directly to the catalyst bed 340. This interstage injection of the
acetone-containing overhead may be used to control concentration
levels in the lower portion of the catalyst bed to minimize
formation of heavy compounds. Thus, dilution of cumene
hydroperoxide feed with acetone is controlled by varying the amount
of acetone recycled to the distillation column, i.e., setting the
reflux rate through the tower, at upper and/or lower portions of
the distillation column, or added directly to the catalyst bed. The
compositions of the proposed feed and estimated product
compositions are provided below in TABLE 4.
4 TABLE 4 Overhead Bottoms Feed Product Product Acetone 0.00 99.63
19.14 Mesityl Oxide 0.00 0.00 0.00 Cumene 7.70 0.00 9.06 Phenol
0.17 0.00 59.71 .alpha.-Methyl Styrene 0.27 0.00 8.35 Acetophenone
2.19 0.00 2.58 2-Phenyl-2-Propanol 7.87 0.00 0.00 Cumene
Hydroperoxide 81.80 0.00 0.00 Water 0.00 0.37 1.16
* * * * *