U.S. patent application number 12/901640 was filed with the patent office on 2011-02-03 for method of making phthalic acid diesters.
This patent application is currently assigned to H R D CORPORATION. Invention is credited to Rayford G. ANTHONY, Ebrahim BAGHERZADEH, Gregory BORSINGER, Abbas HASSAN, Aziz HASSAN.
Application Number | 20110027140 12/901640 |
Document ID | / |
Family ID | 40161396 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110027140 |
Kind Code |
A1 |
HASSAN; Abbas ; et
al. |
February 3, 2011 |
METHOD OF MAKING PHTHALIC ACID DIESTERS
Abstract
Methods and systems for the production of phthalic acid diesters
are described herein. The methods and systems incorporate the novel
use of a high shear device to promote dispersion and mixing of a
phthalic acid derivative with alcohol. The high shear device may
allow for lower reaction temperatures and pressures and may also
reduce reaction time with existing catalysts.
Inventors: |
HASSAN; Abbas; (Sugar land,
TX) ; BAGHERZADEH; Ebrahim; (Sugar Land, TX) ;
ANTHONY; Rayford G.; (College Station, TX) ;
BORSINGER; Gregory; (Chatham, NJ) ; HASSAN; Aziz;
(Sugar Land, TX) |
Correspondence
Address: |
CONLEY ROSE, P.C.;David A. Rose
P. O. BOX 3267
HOUSTON
TX
77253-3267
US
|
Assignee: |
H R D CORPORATION
Houston
TX
|
Family ID: |
40161396 |
Appl. No.: |
12/901640 |
Filed: |
October 11, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12144296 |
Jun 23, 2008 |
|
|
|
12901640 |
|
|
|
|
60946505 |
Jun 27, 2007 |
|
|
|
Current U.S.
Class: |
422/187 ;
422/129; 422/211 |
Current CPC
Class: |
B01J 19/0066 20130101;
B01F 13/1016 20130101; B01F 13/1013 20130101; B01J 19/185 20130101;
Y02P 20/10 20151101; B01F 7/00766 20130101; B01J 14/00 20130101;
B01J 2219/00189 20130101; B01J 2219/00006 20130101; Y02P 20/127
20151101; C07C 67/08 20130101; C07C 67/08 20130101; C07C 69/80
20130101 |
Class at
Publication: |
422/187 ;
422/129; 422/211 |
International
Class: |
B01J 8/02 20060101
B01J008/02; B01J 19/00 20060101 B01J019/00 |
Claims
1. A system for producing phthalic acid diester comprising: at
least one high shear device configured for receiving a mixture
comprising an alcohol and at least one component selected from the
group consisting of phthalic acid and phthalic acid derivatives and
producing a high shear treated stream therefrom, the at least one
high shear device comprising at least one generator comprising a
rotor and a complementarily-shaped stator and operable at a rotor
tip speed of greater than 20 m/s; a pump configured for delivering
the mixture to the at least one high shear device; and a reactor
coupled to the at least one high shear device, the reactor
comprising an inlet for the high shear treated stream and an outlet
for a product comprising phthalic acid diester.
2. The system of claim 1 wherein the at least one high shear device
comprises at least two generators.
3. The system of claim 2 wherein the shear rate provided by one
generator is greater than the shear rate provided by another
generator.
4. The system of claim 1 wherein the at least one high shear device
is operable at a tip speed of at least 40 m/s.
5. The system of claim 1 wherein the high shear device is operable
to subject the mixture to a shear rate of at least 20,000
s.sup.-1.
6. The system of claim 1 wherein the at least one high shear device
is configured to provide an energy expenditure greater than 1000
W/m.sup.3.
7. The system of claim 1 wherein the at least one high shear device
is configured to produce a high shear treated stream comprising gas
bubbles or liquid droplets having a submicron mean diameter.
8. The system of claim 1 wherein the at least one high shear device
is configured to produce a high shear treated stream comprising gas
bubbles or liquid droplets having a mean diameter of less than 400
nm.
9. The system of claim 1 wherein the at least one high shear device
is configured to produce a high shear treated stream comprising gas
bubbles or liquid droplets having a mean diameter of no more than
100 nm.
10. The system of claim 1 comprising at least two high shear
devices.
11. The system of claim 1 wherein the reactor is a fixed bed
reactor.
12. The system of claim 1 wherein the reactor contains a
catalyst.
13. The system of claim 12 wherein the catalyst is selected from
the group consisting of finely divided tin, tin(II) oxide, tin(II)
oxalate, titanate esters, zirconium esters and combinations
thereof.
14. The system of claim 1 wherein the rotor and the stator are
separated by a shear gap in the range of from about 0.02 mm to
about 5 mm, wherein the shear gap is a minimum distance between the
rotor and the stator.
15. The system of claim 1 wherein the at least one high shear
device is external to the reactor.
16. The system of claim 1 wherein the rotor is toothed.
17. The system of claim 1 wherein the mixture further comprises at
least one catalyst selected from the group consisting of sulfuric
acid, hydrochloric acid and aromatic sulfonic acids.
18. The system of claim 1 wherein the reactor is a reactive
distillation column.
19. The system of claim 1 wherein the at least one high shear
device is configured for operating at a flow rate of at least 300
L/h.
20. The system of claim 1 further comprising one or more
distillation columns downstream from the reactor and configured for
separating purified phthalic acid diester from the product.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. Utility
application Ser. No. 12/144,296 filed on Jun. 23, 2008, which
claims the benefit under 35 U.S.C. .sctn.119(e) of U.S. Provisional
Patent Application No. 60/946,505, filed Jun. 27, 2007, the
disclosures of each of which are hereby incorporated herein by
reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND
[0003] 1. Field of the Invention
[0004] This invention relates generally to the field of chemical
reactions. More specifically, the invention relates to methods of
making diester phthalates incorporating high shear mixing.
[0005] 2. Background of the Invention
[0006] Plasticizers are widely used in many ways in plastics,
coating compositions, sealing compositions and rubber articles.
They interact physically with thermoplastic high polymers without
reacting chemically, preferably by means of their solvent and
swelling capability. This forms a homogeneous system whose
thermoplastic range has been shifted to lower temperatures compared
to the original polymer, with the result that, for example, the
ability to change shape and the elasticity are increased and the
hardness is reduced.
[0007] To open up very wide fields of application for plasticizers,
they have to fulfill a number of requirements. In the ideal case,
they should be odorless, colorless, light-resistant, cold-resistant
and heat-resistant. In addition, it is expected that they are
resistant to water, do not burn readily, have a low volatility and
are not harmful to health. Furthermore, the preparation of the
plasticizers should be simple and, to meet ecological demands,
should be carried out without producing waste materials such as
by-products which cannot be recycled and wastewater containing
pollutants.
[0008] Among the most important plasticizers are the esters of
dicarboxylic and polycarboxylic acids with plasticizer alcohols,
i.e. unbranched or branched primary alcohols having from about 6 to
13 carbon atoms, which can be used as individual compounds or as a
mixture. The preparation of the esters has been carried out by the
classical process by reacting the acids or acid anhydrides with an
alcohol or a mixture of different alcohols in the presence of an
acid, preferably sulfuric acid, as catalyst. The alcohol component
is usually used in excess. Attempts have been made to counter
adverse color and odor of the reaction product by targeted
selection of the acid used as catalyst, by mild reaction conditions
and by complicated purification measures.
[0009] A further development in the preparation of esters suitable
as plasticizers constitutes the use of metal-containing
esterification catalysts. Suitable catalysts are, for example, tin,
titanium and zirconium which are used as finely divided metals or
advantageously in the form of their salts, oxides or soluble
organic compounds. These catalysts are high-temperature catalysts
which reach their full activity only at esterification temperatures
above 180.degree. C. Examples are tin powder, tin(II) oxide,
tin(II) oxalate, titanate esters such as tetraisopropyl
orthotitanate or tetrabutyl orthotitanate and also zirconium esters
such as tetrabutyl zirconate. Alkyl titanates and titanium
chelates, i.e. titanates of polyalcohols, have achieved particular
importance in industrial production processes.
[0010] Furthermore, another process for the esterification of
phthalic anhydride involves reaction with isodecanol in the
presence of tetrabutyl titanate as catalyst at 230.degree. C.
Subsequent to the esterification, the reaction mixture is treated
with sodium carbonate solution and the excess alcohol is distilled
off. The treatment with the sodium carbonate solution neutralizes
the phthalic monoesters present in the reaction mixture to form the
corresponding salts. These salts are obtained as a slimy
precipitate which can be filtered off only with difficulty,
necessitating a high outlay in terms of time and apparatus.
Obtaining the desired phthalic diester in pure form is thus
associated with considerable difficulties. The modern processes for
preparing ester plasticizers thus do not yet fulfill all aspects of
the above-described demands made of the production process and the
reaction product.
[0011] Consequently, there is a need for accelerated methods for
esterification by improving the mixing of alcohol into the phthalic
acid derivative phase.
SUMMARY
[0012] Methods and systems for the esterification of phthalic acid
and its derivatives are described herein. The methods and systems
incorporate the novel use of a high shear device to promote
dispersion and solubility of alcohol in the phthalic acid and/or
derivative. The high shear device may allow for lower reaction
temperatures and pressures and may also reduce esterification time.
Further advantages and aspects of the disclosed methods and system
are described below.
[0013] In an embodiment, a method of making a phthalic acid diester
comprises introducing an alcohol into a phthalic acid derivative
stream to form a reactant stream, subjecting the reactant stream to
a shear rate of greater than about 20,000 s.sup.-1 with a high
shear device, and contacting the reactant stream with a catalyst to
make a phthalic acid diester.
In embodiments, gas bubbles are formed in (b), and the gas bubbles
have an average diameter of less than about 400 nm or no more than
about 100 nm. In embodiments, the catalyst comprises sulfuric acid,
hydrochloric acid, aromatic sulfonic acids, benzene sulfonic acid,
p-toluene sulfonic acid, or a combination thereof. In embodiments,
(b) comprises subjecting said reactant stream to high shear mixing
at a tip speed of at least about 23 msec. In embodiments, forming
said dispersion comprises an energy expenditure of at least about
1000 W/m.sup.3. In embodiments, (c) occurs within a reactive
distillation column. In embodiments, the alcohol comprises a
saturated alcohol having from 1 to 10 carbon atoms.
[0014] Also disclosed is a system for producing a phthalic acid
diester, the system comprising at least one high shear device
comprising a rotor and a stator and configured for mixing an
alcohol and a phthalic acid derivative. The rotor and the stator
are separated by a shear gap in the range of from about 0.02 mm to
about 5 mm. The shear gap is a minimum distance between the rotor
and the stator. The high shear device is capable of producing a tip
speed of the at least one rotor of greater than about 23 m/s (4,500
ft/min). In addition, the system comprises a pump configured for
delivering a liquid stream to the high shear device. The system
also comprises a reactor for esterifying the phthalic acid
derivative coupled to the high shear device. The reactor is
configured for receiving said liquid stream from said high shear
device.
[0015] The foregoing has outlined rather broadly the features and
technical advantages of the present invention in order that the
detailed description of the invention that follows may be better
understood. Additional features and advantages of the invention
will be described hereinafter that form the subject of the claims
of the invention. It should be appreciated by those skilled in the
art that the conception and the specific embodiments disclosed may
be readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present
invention. It should also be realized by those skilled in the art
that such equivalent constructions do not depart from the spirit
and scope of the invention as set forth in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a process flow diagram of a process for the
production of phthalic acid diesters, according to certain
embodiments of the invention.
[0017] FIG. 2 is a longitudinal cross-section view of a multi-stage
high shear device, as employed in an embodiment of the system of
FIG. 1.
DETAILED DESCRIPTION
[0018] The disclosed methods and systems for the production of
phthalic acid diester comprises utilization of an external high
shear mechanical device to provide rapid contact and mixing of an
alcohol and a phthalic acid derivative in a controlled environment
in the reactor/mixer device. As used herein, "phthalic acid
derivative" may refer to any compound derived from phthalic acid
including without limitation, phthalic acid, phthalic anhydride,
phthaloyl chloride, etc. The high shear device reduces the mass
transfer limitations on the reaction and thus increases the overall
reaction rate.
[0019] Chemical reactions involving liquids, gases and solids rely
on time, temperature, and pressure to define the rate of reactions.
In cases where it is desirable to react two or more raw materials
of different phases (e.g. solid and liquid; liquid and gas; solid,
liquid and gas), one of the limiting factors in controlling the
rate of reaction involves the contact time of the reactants. In the
case of heterogeneously catalyzed reactions there is the additional
rate limiting factor of having the reacted products removed from
the surface of the catalyst to enable the catalyst to catalyze
further reactants. Contact time for the reactants and/or catalyst
is often controlled by mixing which provides contact with two or
more reactants involved in a chemical reaction. A reactor assembly
that comprises an external high shear device or mixer as described
herein makes possible decreased mass transfer limitations and
thereby allows the reaction to more closely approach kinetic
limitations. When reaction rates are accelerated, residence times
may be decreased, thereby increasing obtainable throughput. Product
yield may be increased as a result of the high shear system and
process. Alternatively, if the product yield of an existing process
is acceptable, decreasing the required residence time by
incorporation of suitable high shear may allow for the use of lower
temperatures and/or pressures than conventional processes.
Homogeneous reactions may also benefit from high shear mixing, as
disclosed herein, by at least providing uniform temperature
distribution within the reactor and minimizing potential side
reactions. Accordingly, in some embodiments, a high shear process
as described herein promotes homogeneous chemical reaction(s).
[0020] System for the Production of Phthalic Acid Diesters. A high
shear phthalic acid diester production system will now be described
in relation to FIG. 1, which is a process flow diagram of an
embodiment of a high shear system 100 for the production of
phthalic acid diesters via the esterification of phthalic acid and
its derivatives with an alcohol in the presence of a catalyst
dispersed in the liquid phase in a reactor 110. Embodiments of the
process are characterized by the use of a high shear device 140 and
introduction of alcohol to the phthalic acid or derivative before
entering the high shear device 140. Generally, embodiments of the
process are carried out by reacting a saturated aliphatic alcohol
containing about 1 to about 10 carbon atoms with a phthalic acid
derivative such as phthalic acid or phthalic anhydride to obtain
the desired diester reaction product.
[0021] The basic components of a representative system include
external high shear device (HSD) 140, vessel 110, and pump 105. As
shown in FIG. 1, the high shear device may be located external to
vessel/reactor 110. Each of these components is further described
in more detail below. Line 121 is connected to pump 105 for
introducing phthalic acid derivative. Line 113 connects pump 105 to
HSD 140, and line 118 connects HSD 140 to vessel 110. Line 122 is
connected to line 113 for introducing the phthalic acid derivative.
Line 117 is connected to vessel 110 for removal of unconverted
reactants. Additional components or process steps may be
incorporated between vessel 110 and HSD 140, or ahead of pump 105
or HSD 140, if desired.
[0022] High shear devices (HSD) such as a high shear device, or
high shear mill, are generally divided into classes based upon
their ability to mix fluids. Mixing is the process of reducing the
size of inhomogeneous species or particles within the fluid. One
metric for the degree or thoroughness of mixing is the energy
density per unit volume that the mixing device generates to disrupt
the fluid particles. The classes are distinguished based on
delivered energy density. There are three classes of industrial
mixers having sufficient energy density to consistently produce
mixtures or emulsions with particle or bubble sizes in the range of
0 to 50 .mu.m. High shear mechanical devices include homogenizers
as well as colloid mills.
[0023] Homogenization valve systems are typically classified as
high energy devices. Fluid to be processed is pumped under very
high pressure through a narrow-gap valve into a lower pressure
environment. The pressure gradients across the valve and the
resulting turbulence and cavitations act to break-up any particles
in the fluid. These valve systems are most commonly used in milk
homogenization and can yield average particle size range from about
0.01 .mu.m to about 1 .mu.m. At the other end of the spectrum are
high shear device systems classified as low energy devices. These
systems usually have paddles or fluid rotors that turn at high
speed in a reservoir of fluid to be processed, which in many of the
more common applications is a food product. These systems are
usually used when average particle, or bubble, sizes of greater
than 20 microns are acceptable in the processed fluid.
[0024] Between low energy-high shear devices and homogenization
valve systems, in terms of the mixing energy density delivered to
the fluid, are colloid mills, which are classified as intermediate
energy devices. The typical colloid mill configuration includes a
conical or disk rotor that is separated from a complementary,
liquid-cooled stator by a closely-controlled rotor-stator gap,
which is maybe between 0.025 mm and 10.0 mm. Rotors are usually
driven by an electric motor through a direct drive or belt
mechanism. Many colloid mills, with proper adjustment, can achieve
average particle, or bubble, sizes of about 0.01 .mu.m to about 25
.mu.m in the processed fluid. These capabilities render colloid
mills appropriate for a variety of applications including colloid
and oil/water-based emulsion processing such as that required for
cosmetics, mayonnaise, silicone/silver amalgam formation, or
roofing-tar mixing.
[0025] An approximation of energy input into the fluid (kW/L/min)
can be made by measuring the motor energy (kW) and fluid output
(L/min). In embodiments, the energy expenditure of a high shear
device is greater than 1000 W/m.sup.3. In embodiments, the energy
expenditure is in the range of from about 3000 W/m.sup.3 to about
7500 W/m.sup.3. The shear rate generated in a high shear device may
be greater than 20,000 s.sup.-1. In embodiments, the shear rate
generated is in the range of from 20,000 s.sup.-1 to 100,000
s.sup.-1.
[0026] Tip speed is the velocity (m/sec) associated with the end of
one or more revolving elements that is transmitting energy to the
reactants. Tip speed, for a rotating element, is the
circumferential distance traveled by the tip of the rotor per unit
of time, and is generally defined by the equation V (m/sec)=.pi.Dn,
where V is the tip speed, D is the diameter of the rotor, in
meters, and n is the rotational speed of the rotor, in revolutions
per second. Tip speed is thus a function of the rotor diameter and
the rotation rate. Also, tip speed may be calculated by multiplying
the circumferential distance transcribed by the rotor tip, 2.pi.R,
where R is the radius of the rotor (meters, for example) times the
frequency of revolution (for example revolutions (meters, for
example) times the frequency of revolution (for example revolutions
per minute, rpm).
[0027] For colloid mills, typical tip speeds are in excess of 23
msec (4500 ft/min) and can exceed 40 msec (7900 ft/min). For the
purpose of the present disclosure the term `high shear` refers to
mechanical rotor-stator devices, such as mills or mixers, that are
capable of tip speeds in excess of 5 msec (1000 ft/min) and require
an external mechanically driven power device to drive energy into
the stream of products to be reacted. A high shear device combines
high tip speeds with a very small shear gap to produce significant
friction on the material being processed. Accordingly, a local
pressure in the range of about 1000 MPa (about 145,000 psi) to
about 1050 MPa (152,300 psi) and elevated temperatures at the tip
of the shear device may be produced during operation. In certain
embodiments, the local pressure is at least about 1034 MPa (about
150,000 psi).
[0028] Referring now to FIG. 1, there is presented a schematic
diagram of a high shear device 200. High shear device 200 comprises
at least one rotor-stator combination. The rotor-stator
combinations may also be known as generators 220, 230, 240 or
stages without limitation. The high shear device 200 comprises at
least two generators, and most preferably, the high shear device
comprises at least three generators.
[0029] The first generator 220 comprises rotor 222 and stator 227.
The second generator 230 comprises rotor 223, and stator 228; the
third generator comprises rotor 224 and stator 229. For each
generator 220, 230, 240 the rotor is rotatably driven by input 250.
The generators 220, 230, 240 rotate about axis 260 in rotational
direction 265. Stator 227 is fixably coupled to the high shear
device wall 255.
[0030] The generators include gaps between the rotor and the
stator. The first generator 220 comprises a first gap 225; the
second generator 230 comprises a second gap 235; and the third
generator 240 comprises a third gap 245. The gaps 225, 235, 245 are
between about 0.025 mm (0.01 in) and 10.0 mm (0.4 in) wide.
Alternatively, the process comprises utilization of a high shear
device 200 wherein the gaps 225, 235, 245 are between about 0.5 mm
(0.02 in) and about 2.5 mm (0.1 in). In certain instances the gap
is maintained at about 1.5 mm (0.06 in). Alternatively, the gaps
225, 235, 245 are different between generators 220, 230, 240. In
certain instances, the gap 225 for the first generator 220 is
greater than about the gap 235 for the second generator 230, which
is greater than about the gap 245 for the third generator 240.
[0031] Additionally, the width of the gaps 225, 235, 245 may
comprise a coarse, medium, fine, and super-fine characterization.
Rotors 222, 223, and 224 and stators 227, 228, and 229 may be
toothed designs. Each generator may comprise two or more sets of
rotor-stator teeth, as known in the art. Rotors 222, 223, and 224
may comprise a number of rotor teeth circumferentially spaced about
the circumference of each rotor. Stators 227, 228, and 229 may
comprise a number of stator teeth circumferentially spaced about
the circumference of each stator. The rotor and the stator may be
of any suitable size. In one embodiment, the inner diameter of the
rotor is about 64 mm and the outer diameter of the stator is about
60 mm. In other embodiments, the inner diameter of the rotor is
about 11.8 cm and the outer diameter of the stator is about 15.4
cm. The rotor and stator may have alternate diameters in order to
alter the tip speed and shear pressures. In certain embodiments,
each of three stages is operated with a super-fine generator,
comprising a gap of between about 0.025 mm and about 3 mm. When a
feed stream 205 including solid particles is to be sent through
high shear device 200, the appropriate gap width is first selected
for an appropriate reduction in particle size and increase in
particle surface area. In embodiments, this is beneficial for
increasing catalyst surface area by shearing and dispersing the
particles.
[0032] High shear device 200 is fed a reaction mixture comprising
the feed stream 205. Feed stream 205 comprises an emulsion of the
dispersible phase and the continuous phase. Emulsion refers to a
liquefied mixture that contains two distinguishable substances (or
phases) that will not readily mix and dissolve together. Most
emulsions have a continuous phase (or matrix), which holds therein
discontinuous droplets, bubbles, and/or particles of the other
phase or substance. Emulsions may be highly viscous, such as
slurries or pastes, or may be foams, with tiny gas bubbles
suspended in a liquid. As used herein, the term "emulsion"
encompasses discontinuous phases comprising gas bubbles, particles
(e.g., solid catalyst), or droplets of a fluid that is
substantially insoluble in the continuous phase, and combinations
thereof.
[0033] Feed stream 205 may include a particulate solid catalyst
component. Feed stream 205 is pumped through the generators 220,
230, 240, such that product dispersion 210 is formed. In each
generator, the rotors 222, 223, 224 rotate at high speed relative
to the fixed stators 227, 228, 229. The rotation of the rotors
pumps fluid, such as the feed stream 205, between the outer surface
of the rotor 222 and the inner surface of the stator 227 creating a
localized high shear condition. The gaps 225, 235, 245 generate
high shear forces that process the feed stream 205. The high shear
forces between the rotor and stator functions to process the feed
stream 205 to create the product dispersion 210. Each generator
220, 230, 240 of the high shear device 200 has interchangeable
rotor-stator combinations for producing a narrow distribution of
the desired bubble size, if feedstream 205 comprises a gas, or
globule size, if feedstream 205 comprises a liquid, in the product
dispersion 210.
[0034] The product dispersion 210 of gas particles, or bubbles, in
a liquid comprises an emulsion. In embodiments, the product
dispersion 210 may comprise a dispersion of a previously immiscible
or insoluble gas, liquid or solid into the continuous phase. The
product dispersion 210 has an average gas particle, or bubble, size
less than about 1.5 .mu.m; preferably the bubbles are sub-micron in
diameter. In certain instances, the average bubble size is in the
range from about 1.0 .mu.m to about 0.1 .mu.m. Alternatively, the
average bubble size is less than about 400 nm (0.4 .mu.m) and most
preferably less than about 100 nm (0.1 .mu.m).
[0035] The high shear device 200 produces a gas emulsion capable of
remaining dispersed at atmospheric pressure for at least about 15
minutes. For the purpose of this disclosure, an emulsion of gas
particles, or bubbles, in the dispersed phase in product dispersion
210 that are less than 1.5 .mu.m in diameter may comprise a
micro-foam. Not to be limited by a specific theory, it is known in
emulsion chemistry that sub-micron particles, or bubbles, dispersed
in a liquid undergo movement primarily through Brownian motion
effects. The bubbles in the emulsion of product dispersion 210
created by the high shear device 200 may have greater mobility
through boundary layers of solid catalyst particles, thereby
facilitating and accelerating the catalytic reaction through
enhanced transport of reactants.
[0036] The rotor is set to rotate at a speed commensurate with the
diameter of the rotor and the desired tip speed as described
hereinabove. Transport resistance is reduced by incorporation of
high shear device 200 such that the velocity of the reaction is
increased by at least about 5%. Alternatively, the high shear
device 200 comprises a high shear colloid mill that serves as an
accelerated rate reactor (ARR). In embodiments, the accelerated
rate reactor can comprises a single stage dispersing chamber. In
embodiments, the accelerated rate reactor comprises a multiple
stage inline disperser comprising at least 2 stages.
[0037] Selection of the high shear device 200 is dependent on
throughput requirements and desired particle or bubble size in the
outlet dispersion 210. In certain instances, high shear device 200
comprises a DISPAX REACTOR.RTM. of IKA.RTM. Works, Inc. Wilmington,
N.C. and APV North America, Inc. Wilmington, Mass. Model DR 2000/4,
for example, comprises a belt drive, 4M generator, PTFE sealing
ring, inlet flange 1'' sanitary clamp, outlet flange 3/4'' sanitary
clamp, 2 HP power, output speed of 7900 rpm, flow capacity (water)
approximately 300 L/h to approximately 700 L/h (depending on
generator), a tip speed of from 9.4 m/s to about 41 m/s (about 1850
ft/min to about 8070 ft/min). Several alternative models are
available having various inlet/outlet connections, horsepower,
nominal tip speeds, output rpm, and nominal flow rate.
[0038] Without wishing to be limited to a particular theory, it is
believed that the level or degree of high shear mixing is
sufficient to increase rates of mass transfer and may also produce
localized non-ideal conditions that enable reactions to occur that
would not otherwise be expected to occur based on Gibbs free energy
predictions. Localized non ideal conditions are believed to occur
within the high shear device resulting in increased temperatures
and pressures with the most significant increase believed to be in
localized pressures. The increase in pressures and temperatures
within the high shear device are instantaneous and localized and
quickly revert back to bulk or average system conditions once
exiting the high shear device. In some cases such as in homogeneous
liquid phase reactions, the high shear device induces cavitation of
sufficient intensity to dissociate one or more of the reactants
into free radicals, which may intensify a chemical reaction or
allow a reaction to take place at less stringent conditions than
might otherwise be required. Cavitation may also increase rates of
transport processes by producing local turbulence and liquid
micro-circulation (acoustic streaming).
[0039] Vessel. Vessel or reactor 110 is any type of vessel in which
a multiphase reaction can be propagated to carry out the
above-described conversion reaction(s). For instance, a continuous
or semi-continuous stirred tank reactor, or one or more batch
reactors may be employed in series or in parallel. In some
applications vessel 110 may be a tower reactor, and in others a
tubular reactor or multi-tubular reactor. A catalyst inlet line 115
may be connected to vessel 110 for receiving a catalyst solution or
slurry during operation of the system.
[0040] Vessel 110 may include one or more of the following
components: stirring system, heating and/or cooling capabilities,
pressure measurement instrumentation, temperature measurement
instrumentation, one or more injection points, and level regulator
(not shown), as are known in the art of reaction vessel design. For
example, a stirring system may include a motor driven mixer. A
heating and/or cooling apparatus may comprise, for example, a heat
exchanger. Alternatively, as much of the conversion reaction may
occur within HSD 140 in some embodiments, vessel 110 may serve
primarily as a storage vessel in some cases. Although generally
less desired, in some applications vessel 110 may be omitted,
particularly if multiple high shear devices/reactors are employed
in series, as further described below.
[0041] Heat Transfer Devices. In addition to the above-mentioned
heating/cooling capabilities of vessel 110, other external or
internal heat transfer devices for heating or cooling a process
stream are also contemplated in variations of the embodiments
illustrated in FIG. 1. Some suitable locations for one or more such
heat transfer devices are between pump 105 and HSD 140, between HSD
140 and vessel 110, and between vessel 110 and pump 105 when system
1 is operated in multi-pass mode. Some non-limiting examples of
such heat transfer devices are shell, tube, plate, and coil heat
exchangers, as are known in the art.
[0042] Pumps. Pump 105 is configured for either continuous or
semi-continuous operation, and may be any suitable pumping device
that is capable of providing greater than 2 atm pressure,
preferably greater than 3 atm pressure, to allow controlled flow
through HSD 140 and system 1. For example, a Roper Type 1 gear
pump, Roper Pump Company (Commerce Ga.) Dayton Pressure Booster
Pump Model 2P372E, Dayton Electric Co (Niles, Ill.) is one suitable
pump. Preferably, all contact parts of the pump comprise stainless
steel. In some embodiments of the system, pump 105 is capable of
pressures greater than about 20 atm. In addition to pump 105, one
or more additional, high pressure pump (not shown) may be included
in the system illustrated in FIG. 1. For example, a booster pump,
which may be similar to pump 105, may be included between HSD 140
and vessel 110 for boosting the pressure into vessel 110. As
another example, a supplemental feed pump, which may be similar to
pump 105, may be included for introducing additional reactants or
catalyst into vessel 110.
[0043] Production of Phthalic Acid Diesters. In operation for the
production of phthalic acid diester, the method can comprise
introducing an alcohol into system 100 via line 122, into a
phthalic acid derivative stream 112. Alternatively, the alcohol may
be fed directly into HSD 140. Pump 105 is operated to pump the
phthalic acid derivative stream through line 121, and to build
pressure and feed HSD 140, providing a controlled flow throughout
high shear device (HSD) 140 and high shear system 100.
[0044] In a preferred embodiment, alcohol may continuously be fed
into the phthalic acid derivative stream 112 to form reactant
stream 113. In high shear device 140, the alcohol and phthalic acid
derivative are highly mixed such that nanobubbles and/or
microbubbles are formed for superior dissolution of alcohol into
solution. Once dispersed, the reaction stream may exit high shear
device 140 at high shear device outlet line 118. Stream 118 may
optionally enter fluidized or fixed bed 142 in lieu of a slurry
catalyst process. However, in a slurry catalyst embodiment, high
shear outlet stream 118 may directly enter reactor 110 for
reaction. The reaction stream may be maintained at the specified
reaction temperature, using cooling coils in the reactor 110 to
maintain reaction temperature. Reaction products (e.g. phthalic
acid diester) may be withdrawn in the form of vapors at product
stream 116.
[0045] In embodiments, the phthalic acid diester produced may have
the following formula:
##STR00001##
where R is an alkyl group having from 1 to 10 carbon atoms and R
may be branched or unbranched.
[0046] While embodiments of the process are particularly concerned
with the production of the highly advantageous diesters of phthalic
acid and its derivatives which are required in large quantities for
use as plasticizers for organic polymers such as polyvinyl
chloride, the disclosed process may be applicable to the production
of esters of suitable aliphatic and other aromatic dicarboxylic
acids or anhydrides thereof, for example, maleic anhydride, fumaric
acid, and other dicarboxylic acids of the formula:
HOOC--(CH.sub.2).sub.n--COOH
in which n denotes a whole number of from 1 to 8, as exemplified by
such acids as malonic acid, succinic acid, glutaric acid, adipic
acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.
Examples of suitable saturated aliphatic alcohols having about 1 to
about 10 carbon atoms are propanol, ethanol, butanol, n-octanol-1,
n-octanol-2,2-ethyl-hexanol-1, n-nonyl alcohol, isodecanol, and
decanol.
[0047] In an exemplary embodiment, the high shear device comprises
a commercial disperser such as IKA.RTM. model DR 2000/4, a high
shear, three stage dispersing device configured with three rotors
in combination with stators, aligned in series. The disperser is
used to create the mixture of alcohol and the phthalic acid
derivative. The rotor/stator sets may be configured as illustrated
in FIG. 2, for example. The combined reactants enter the high shear
device via line 113 and enter a first stage rotor/stator
combination having circumferentially spaced first stage shear
openings. The coarse dispersion exiting the first stage enters the
second rotor/stator stage, which has second stage shear openings.
The reduced bubble-size dispersion emerging from the second stage
enters the third stage rotor/stator combination having third stage
shear openings. The dispersion exits the high shear device via line
118. In some embodiments, the shear rate increases stepwise
longitudinally along the direction of the flow. For example, in
some embodiments, the shear rate in the first rotor/stator stage is
greater than the shear rate in subsequent stage(s). In other
embodiments, the shear rate is substantially constant along the
direction of the flow, with the stage or stages being the same. If
the high shear device includes a PTFE seal, for example, the seal
may be cooled using any suitable technique that is known in the
art. For example, the reactant stream flowing in line 113 may be
used to cool the seal and in so doing be preheated as desired prior
to entering the high shear device.
[0048] The rotor of HSD 140 is set to rotate at a speed
commensurate with the diameter of the rotor and the desired tip
speed. As described above, the high shear device (e.g., colloid
mill) has either a fixed clearance between the stator and rotor or
has adjustable clearance. HSD 140 serves to intimately mix the
reactant liquids (i.e., phthalic acid derivative and alcohol). In
some embodiments of the process, the transport resistance of the
reactants is reduced by operation of the high shear device such
that the velocity of the reaction is increased by greater than a
factor of about 5. In some embodiments, the velocity of the
reaction is increased by at least a factor of 10. In some
embodiments, the velocity is increased by a factor in the range of
about 10 to about 100 fold. In some embodiments, HSD 140 delivers
at least 300 L/h with a power consumption of 1.5 kW at a nominal
tip speed of at least 4500 ft/min (23 m/s), and which may exceed
7900 ft/min (40 m/s). Although measurement of instantaneous
temperature and pressure at the tip of a rotating shear unit or
revolving element in HSD 140 is difficult, it is estimated that the
localized temperature seen by the intimately mixed reactants may be
in excess of 500.degree. C. and at pressures in excess of 500
kg/cm.sup.2 under high shear conditions. The high shear mixing
results in formation of micron or submicron-sized bubbles due to
cavitation. In some embodiments, the resultant dispersion has an
average bubble size less than about 1.5 .mu.m. Accordingly, the
stream exiting HSD 140 via line 118 may comprise micron and/or
submicron-sized bubbles. In some embodiments, the mean bubble size
is in the range of about 0.4 .mu.m to about 1.5 .mu.m. In some
embodiments, the mean bubble size is less than about 400 nm, and
may be about 100 nm in some cases. In many embodiments, the
microbubble dispersion is able to remain dispersed at atmospheric
pressure for at least 15 minutes.
[0049] Once sheared, the resulting phthalic acid derivative/alcohol
solution exits HSD 140 via line 118 and feeds into vessel 110, as
illustrated in FIG. 1. As a result of the intimate mixing of the
reactants prior to entering vessel 110, a significant portion of
the chemical reaction may take place in HSD 140, with or without
the presence of a catalyst. Accordingly, in some embodiments,
reactor/vessel 110 may be used primarily for heating and separation
of volatile reaction products from the phthalic acid diester
product. Alternatively, or additionally, vessel 110 may serve as a
primary reaction vessel where most of the phthalic acid diester
product is produced. Vessel/reactor 110 may be operated in either
continuous or semi-continuous flow mode, or it may be operated in
batch mode. The contents of vessel 110 may be maintained at a
specified reaction temperature using heating and/or cooling
capabilities (e.g., cooling coils) and temperature measurement
instrumentation. In and embodiment, vessel 110 may be a reactive
distillation column. Pressure in the vessel may be monitored using
suitable pressure measurement instrumentation, and the level of
reactants in the vessel may be controlled using a level regulator
(not shown), employing techniques that are known to those of skill
in the art. The contents are stirred continuously or
semi-continuously.
[0050] The reaction may proceed under temperature and pressure
conditions commonly employed in such catalytic esterification
reactions. There is no particular restriction as to the reaction
conditions. However, the pressure is selected usually within a
range of from about atmospheric pressure to 10 MPa, alternatively
from about 2 to about 4 MPa, and the reaction temperature may be
within a range of from about 15.degree. C. to about 350.degree. C.,
alternatively from about 75.degree. C. to about 150.degree. C.
[0051] As discussed above, the phthalic acid derivative supplied to
line 112 may be any phthalic acid derivative known by those of
skill in the art to produce phthalic acid diester. Examples include
without limitation, phthalic acid, phthalate anhydride, and the
like. Sources of the derivatives may be from any suitable source.
Likewise, the alcohol for the reaction may come from any suitable
source. For example, the alcohol may be the result of ethylene
hydration, a Fischer-Tropsch process, or a fermentation
process.
[0052] The reaction solution may be further processed prior to
entering vessel 110 if desired. The contents of the vessel are
stirred continuously or semi-continuously, the temperature of the
reactants is controlled (e.g., using a heat exchanger), and the
fluid level inside vessel 110 is regulated using standard
techniques. The reaction may occur either continuously,
semi-continuously or batch wise, as desired for a particular
application. Any by-products that are produced may exit reactor 110
via line 117. This exit stream 117 may comprise water formed from
the esterification reaction and may be withdrawn from water outlet
stream 117.
[0053] The combined distillable products may then be separated in a
series of distillation steps to give phthalic acid diester, the
product; unconverted acetaldehyde, for recycle; light ends which
can be used for fuel; a mixture of phthalic acid diester and
ethanol, and a by-product, acetaldehyde diethyl acetal, which can
be recovered for sale or hydrolyzed for recovery of acetaldehyde
and ethanol.
[0054] Dibutyl phthalate may be produced from the above disclosed
process. Phthalic anhydride and butanol may be mixed in a high
shear device to form a reaction mixture stream. The reaction
mixture may include a catalyst to form a slurry reaction mixture or
the reaction mixture may be flowed through a fixed or fluidized bed
reactor. The reaction is shown below:
##STR00002##
[0055] Other known methods of producing phthalic acid diester may
be also used with a high shear device 140.
[0056] Catalyst. The process can take place in the presence of a
catalyst or without catalyst. The catalysts are generally strong
mineral acids such as sulfuric acid or hydrochloric acid, and
aromatic sulfonic acids, such as benzene sulfonic acid, para
toluene sulfonic acid, and mixtures thereof. In addition, aluminum
chloride, zinc chloride, and Lewis acids such as boron trifluoride
are also useful catalysts as are aliphatic sulfonic acids. In
addition, amphoteric-based compounds have been used as catalysts,
for example, divalent tin oxide, divalent tin oxalate, metallic
tin, bismuth oxide and mixtures thereof. These amphoteric-based
catalysts have been, however, mostly used in batch processes for
the production of phthalic esters.
[0057] Recently, lower alkyl titanium esters and lower alkyl
zirconium esters have been utilized as catalysts for the production
of phthalic esters in both batch and continuous processes.
Generally said ester catalysts contain about 3 to about 8 carbon
atoms in the alkyl group. Useful examples of the titanium esters
are isopropyl titanate, 2-ethyl hexyl titanate and n-butyl
titanate.
[0058] If a catalyst is used to promote the reaction, it may be
introduced into the vessel via line 115, as an aqueous or
nonaqueous slurry or stream. Alternatively, or additionally,
catalyst may be added elsewhere in the system 100. For example,
catalyst slurry may be injected into line 121.
[0059] A strong acid ion exchange resin such as Rohm and Haas A-16
can be used in the reactor 110. The catalyst is employed in an
amount sufficient to initiate and maintain reaction. A homogeneous
catalyst liquid phase or a pump around bed, which enable the liquid
to be pumped across a packed bed of solid catalyst 142 can be
employed within the scope of the method. Catalyst may be fed into
reactor 110 through catalyst feed stream 115.
[0060] As mentioned above, stream 118 may optionally enter
fluidized or fixed bed 142 in lieu of a slurry catalyst process.
However, in a slurry catalyst embodiment, high shear outlet stream
118 may directly enter reactor 110 for phthalic acid diester
production. Where a slurry based catalyst is utilized, reaction is
more likely to occur at points outside the reactor (110) shown in
FIG. 1. Nonetheless a discrete reactor is often desirable to allow
for increased residence time, agitation and heating and/or cooling.
When fixed bed catalyst is utilized, the reactor becomes the main
location for the reaction to occur due to the presence of catalyst.
The reaction stream may be maintained at the specified reaction
temperature, using cooling coils in the reactor 110 to maintain
reaction temperature.
[0061] Multiple Pass Operation. In the embodiment shown in FIG. 1,
the system is configured for single pass operation, wherein the
output from vessel 110 goes directly to further processing for
recovery of phthalic acid diester product. In some embodiments it
may be desirable to pass the contents of vessel 110, or a liquid
fraction containing phthalic acid diester product, unreacted
alcohol and/or phthalic acid diester derivative, through HSD 140
during a second pass. In this case, line 116 is connected to line
121 via dotted line 120, and the recycle stream from vessel 110 is
pumped by pump 105 into line 113 and thence into HSD 140.
Additional alcohol may be injected via line 122 into line 113, or
it may be added directly into the high shear device (not
shown).
[0062] Multiple High Shear devices. In some embodiments, two or
more high shear devices like HSD 140, or configured differently,
are aligned in series, and are used to further enhance the
reaction. Their operation may be in either batch or continuous
mode. In some instances in which a single pass or "once through"
process is desired, the use of multiple high shear devices in
series may also be advantageous. In some embodiments where multiple
high shear devices are operated in series, vessel 110 may be
omitted. In some embodiments, multiple high shear devices 140 are
operated in parallel, and the outlet dispersions therefrom are
introduced into one or more vessel 110.
[0063] While embodiments of the invention have been shown and
described, modifications thereof can be made by one skilled in the
art without departing from the spirit and teachings of the
invention. The embodiments described herein are exemplary only, and
are not intended to be limiting. Many variations and modifications
of the invention disclosed herein are possible and are within the
scope of the invention. Where numerical ranges or limitations are
expressly stated, such express ranges or limitations should be
understood to include iterative ranges or limitations of like
magnitude falling within the expressly stated ranges or
limitations. Use of broader terms such as comprises, includes,
having, etc. should be understood to provide support for narrower
terms such as consisting of, consisting essentially of, comprised
substantially of, and the like. Accordingly, the scope of
protection is not limited by the description set out above but is
only limited by the claims which follow, that scope including all
equivalents of the subject matter of the claims. Each and every
original claim is incorporated into the specification as an
embodiment of the invention. Thus, the claims are a further
description and are an addition to the preferred embodiments of the
present invention. The disclosures of all patents, patent
applications, and publications cited herein are hereby incorporated
by reference, to the extent they provide exemplary, procedural or
other details supplementary to those set forth herein.
* * * * *