U.S. patent application number 11/454044 was filed with the patent office on 2007-12-20 for low cost high yield iso-octene/ isooctane process with capability to revamp the mtbe units.
This patent application is currently assigned to Refining Hydrocarbon Technologies LLC. Invention is credited to Amarjit Singh Bakshi.
Application Number | 20070293711 11/454044 |
Document ID | / |
Family ID | 38862445 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070293711 |
Kind Code |
A1 |
Bakshi; Amarjit Singh |
December 20, 2007 |
Low cost high yield Iso-octene/ Isooctane process with capability
to revamp the MTBE units
Abstract
This invention covers a process for dimerizing of isobutylene to
Iso-octene and unique configuration is being disclosed, where the
Feed is diluted to low level with recycle which has essentially no
Iso-octene, dual catalyst system, new selectivator (IPA) and
successive catalyst stages if needed to enhance the conversion. The
process is very selective and provides higher isobutylene
conversion. Additionally the invention also covers the
hydrogenation of olefins to Paraffin, Iso-octene to Iso-octane
product under moderate conditions and with dual or single catalyst
system.
Inventors: |
Bakshi; Amarjit Singh;
(Katy, TX) |
Correspondence
Address: |
AMARJIT SINGH BAKSHI;REFINING HYDROCARBON TECHNOLOGIES LLC
20130 CHATEAU BEND DRIVE
KATY
TX
77450
US
|
Assignee: |
Refining Hydrocarbon Technologies
LLC
Katy
TX
|
Family ID: |
38862445 |
Appl. No.: |
11/454044 |
Filed: |
June 15, 2006 |
Current U.S.
Class: |
585/502 |
Current CPC
Class: |
C10G 2300/4018 20130101;
C10G 2300/4006 20130101; C07C 2523/42 20130101; Y02P 20/582
20151101; C10G 2400/02 20130101; C07C 2523/883 20130101; C07C 2/28
20130101; C07C 5/03 20130101; C07C 2523/44 20130101; C07C 2531/08
20130101; C10G 50/00 20130101; C10G 2300/4081 20130101; C07C
2523/888 20130101; C10G 2300/1088 20130101; C10G 2300/4012
20130101; C07C 2523/882 20130101; Y02P 20/10 20151101; C07C 9/21
20130101; Y02P 20/127 20151101; C07C 2523/755 20130101; C07C
2531/10 20130101 |
Class at
Publication: |
585/502 |
International
Class: |
C07C 2/02 20060101
C07C002/02 |
Claims
1. A Process for producing Iso-octene Comprising: A) Dimerizing the
isobutylene in the FC C, Steam Cracker, Thermal Cracker or on
purpose dehydrogenation streams, in the presence of sulfonated
resin catalyst Amberlyst 15, 35 or 36 or equivalent at moderate
temperatures as defined in the process invention. The process uses
a top bed of catalyst which is for selective hydrogenation e.g.
Palladium, Nickel, Resin doped Palladium, Nickel/Mo, Co/Mo. Ni/W or
Pd/Pt etc. but not limited to, so as perform selective
hydrogenation of dioolefins in the Feed, followed by normal resin
catalysts Amberlyst 15, 35, 35 or equivalent. The WHSV is 5 to 15
for first catalyst bed, which is hydrogenation catalyst, and 3 to 6
for the resin catalyst, on fresh Feed basis. The temperature is in
the range of 100 to 160 F, and pressure is 100 to 175 psig at the
reactor inlet. B) Taking total sidedraws or partial sidedraws from
the debutanizer after the Iso-octene and heavy's have gone down the
column, and recycling it to the Ist Reactor to reduce the
concentration of the isobutylene in the reactor. This recycle
reduces the isobutylene concentration to half to one fifth compared
to fresh Feed isobutylene concentration. C) Providing small amount
of propylene in the feed so that it is hydrated and makes Isopropyl
alcohol (IPA), which is used as solvator/Selectivator to enhance
the catalyst activity. This is recycled in the system with the
C.sub.4 stream so as to make very small amount of IPA. D) To
enhance the conversion part of the recycle stream is sent to the
side Reactor which enhances the conversion and selectivity. It is
claimed that the liquid is returned at the same location from where
the sidedraw was taken or at a suitable location, so as to have no
effect on size of the debutanizer column design. E) The special art
in the configuration is being used in the process so as to recycle
sidedraw's which provide the dilution an some of unconverted
isobutylene is recycled in turn, new selectivator (IPA) to get the
best results in conversion to solvate the catalyst, yield and
selectivity. The configuration is also invented to install bulk
catalyst in the column by installing Johnson Screens in the column,
so the catalyst and holddown grid with Johnson screen to secure the
catalyst at the top of the bed. This allows easy revamp of the
existing reactive distillation applications, but are cumbersome to
install catalyst and the cost is higher than the catalyst from the
vendor. The art of by passing the vapor with chimney trays or
external pipes is being used as these reaction are taking place in
liquid phase (vapor does not contribute to the reaction). Multiple
beds can be used. F) Either sidedraw from the debutanizer can be
used to take IPA with C.sub.4 stream, or the IPA together with
iso-octene can be sent to another column or existing alcohol
recovery column. The existing alcohol recovery column or the
Iso-octene column, can be used for the separation of IPA, and is
recycled whereas Iso-octene sent to OSBL after cooling or can be
sent to Iso-octane unit without cooling as required. The C.sub.4
sidedraw are still taken from the debutanizer column for dilution
for the 1 st reactor and also feed to the side reactor. G) This
invention also covers the dimerization of iso-amylene to produce
Di-isoamylene. RHT process provides selectively, similar to
Iso-octene process. H) Normal precautions are taken for removing
the poison from the Feed by either water wash or adsorbent
media.
2. The method of claim 1, A) Where as in the art of this invention
uses dual catalyst system. The first bed at the top, in the 1 st
reactor is a trifunctional catalyst (sulfonated Resin catalyst
doped in Palladium e.g. Amberlyst CH10 or Levatit K 2624) or
Palladium or Nickel catalyst so as to selectively hydrogenate the
diolefins and stabilize the olefins, which enhances the catalyst
life. This is done at very high space velocity so as to keep the
catalyst cost low. The selective hydrogenationeither in the
iso-octene unit or upstream is exclusively being claimed by RHT
Iso-octene process and one of the major claims for this
application. B) Hydrogen is expected to be close to stiochiometric
for diolefin selective hydrogenation in the reactor, as the
intention is to see that all the hydrogen is consumed and no
olefins are saturated. C) The process claims the highest yield, low
n-butylene loss to codimers, high selectivity and enhanced catalyst
life due to dual catalyst bed and also using a better selectivator
(IPA) and low isobutylene concentration due to dilution by
recycle.
3. The process is designed to hydrogenate the Iso-octene to
Iso-octane: A) The method of claim 3, the invention uses the art so
as to have milder conditions and using two stage approach for
hydrogenation of olefins to paraffins, by using, Nickel Catalyst
(or Nickel/Molybdenum, Nickel/Tungsten, Palladium,
Palladium/Platinum) in the 1st Reactor with excess hydrogen than
stoichiometric. Reactor effluent is flashed, the liquid after the
flash from first reactor, is recycled to first reactor as heat sink
(after cooling to remove the heat of reaction) and part of this
liquid is forward feed to the Finishing Reactor which could have
either Palladium Catalyst (Palladium/Platinum or Nickel catalyst
similar to in the 1st reactor). The invention claims 99%
hydrogenation of olefins to paraffins. B) The method of claim 3,
Where 1st Reactor operates at inlet pressure of 250 psig to 450
psig (preferably closer to 250 psig) and temperature of 200 to 350
F (preferably 260 F), and recycle liquid is provided after the
flash as shown in FIG. 6, as a heat sink so as to have temperature
rise in the reactor of 50 to 150 F (preferably 100 F). Part of the
flashed liquid after 70 to 90% hydrogenation in the 1st Reactor, is
sent to the finishing reactor to complete the olefin hydrogenation
to Paraffin to 99%. C) The method of claim 3, where WHSV in the 1st
Reactor is kept in the range 1 to 4 (closer to 2) based on fresh
Feed basis, Finishing Reactor WHSV is 2 to 4 (closer to 2). The
FIG. 6 shows the detail of this configuration. D) The method of
claim 3, where the hydrogen is 1.2 to 2.0 times (closer to 1.4
times) the stoichiometric required for olefin saturation to
Paraffin. The Reactor is designed to operate in single phase or
two-phase operation, which ever is most cost effective.
Description
FIELD OF THE INVENTION
[0001] The invention relates to producing dimer of Isobutylene
especially but covers the dimerazation of Isoamylenes as well. The
Isobutylene dimerization provides a dimer but some of the normal
butylenes' react with iso-butylene to produces some of isomers of
these dimers. This dimer which is di-isobutylene is called commonly
as Iso-octene is high octane compound similar to MTBE but without
the environmental problems of MTBE. The major problem is this
product is essentially olefinic and when there are specification as
regards to olefin than it will have to be hydrogenated to
Isooctane. Most of the MTBE plants can be converted to Iso-octene
with little investment but one needs some higher capital investment
for hydrogenation of Is-octene to Iso-octane. Additional drawback
is that the Isooctene yield compared to MTBE is reducede by about
70 percent. The art of this invention relates specifically to a new
selectivator for the catalyst and also unique configuration so as
to produce higher selectivity product and enhancing the yield as
well. This will be explained fully in the Figures so as to make it
more understandable to the individuals who are familiar with the
art of catalytic reactions.
[0002] The invention also covers the hydrogenation of Iso-octene to
Iso-octane (to 99% hydrogenation of olefins) in dual catalyst
system at lower pressure than the competing technologies, reducing
the cost.
BACKGROUND OF THE INVENTION
[0003] Low molecular weight unsymmetrical Ethers such as MTBE, ETBE
are produced from iso-olefins and methanol/Ethanol reaction in the
presence of acidic sulfonated ion exchange catalyst (e.g. Amberlyst
15 or 35 or equivalent) to produce ethers and are commonly added to
the gasoline so as reduce the pollution due to better burning
qualities of these Ethers and Lower vapor presssure as well, which
provide good burning gasoline, due to additional oxygen added
through alcohol, and the combustion products have reduced CO in the
combustion products. As this addition of Ethers was mandated by the
Clean Air act of 1990 by EPA. These ethers have much higher octane
and lower RVP of the gasoline blend that reduces the VOC's in the
atmosphere. Addition of these compounds works as diluent also,
which in turn reduce the other components of the gasoline blend
like benzene, aromatics and olefins. In recent years due leakage of
MTBE from the gas stations storage tanks, some leaks from using it
in water skies in lakes, and as solubility of the MTBE in water is
high, it has created controversy as regards to suitability of the
ethers in gasoline especially in USA. Some over 20 odd states in
USA have banned Ether addition in gasoline, and other states might
follow the trend, though it is still being used in RFG in some
states in USA. In USA approximately 230,000 bbl/d of Ethers was
being used in the gasoline, and if it is taken away as being
suggested and is being forcasted, it will have atleast about 70,000
bbl/d of shortfall of gasoline if Iso-octene is produced. Thus
producing of Iso-octene via this route will be a low cost option.
But if the Isobutylene can be alkylated with other normal olefins
in the alkylation plant (which is normally being done for n-butenes
if MTBE units are upstream) and lot of the Alkylation plants will
have revamped any way. The product will be higher than the Ethers
but of lower octane. But one should note that alkylate is one of
the most desirable component of the gasoline pool with reasonable
high octane, no aromatics and no sulfur. But the alkylation plants
need much higher investment and some cases would make economic
sense to produce Iso-octene and/or iso-octane via dimerization
route and than if need be hydrogenating the product to reduce the
olefin content, and it all depends on the economics of each plant
and the specification and the complexity of the refinery which
produces the gasoline components.
[0004] The invention is in the field of dimerization of isobutylene
in the presence sulfonated resin catalyst (e.g. Amberlyst 15 or 35
or equivalent), together with an trifunctional catalyst which is
essentially resin catalyst doped into palladium (two bed approach
in the reactor) and a new selectivator for solvating the catalyst
which is Isopropyl alcohol. The configuration is provided to dilute
the isobutylene in the feed to 5% or less by unique cofiguration
and recycle of Iso-propyl alcohol and dual bed catalyst provides
selective conversion of Isobutylene to dimer (Iso-octene),
essentially 10 to 20% of the 1-butene plus 2-butenes also goes in
the reaction to form codimers. In the reaction some trimer is also
formed with small amount of tetramer and also some C8 Ethers as
will be shown in the reaction Chemistry section of this patent. The
palladium-doped resin catalyst selectively hydrogenates the
butadiene and also stabilizes the olefins, which provide the longer
catalyst life, as it does not polymerize on the catalyst.
[0005] The present disclosure and the art describes a process for
producing Iso-octene and Iso-octane by dimerizing the isobutylene
in C.sub.4 stream in the fixed bed down flow reactor(s). In
general, isobutylene dimerization process is done in the presence
of similar acid catalysts that are used for etherification. We have
selected a dual and different catalyst to do the dimerization to
enhance the catalyst life. Essentially, the process uses an art of
using a small amount of selectivator for solvating the catalyst
that helps in the reactions sites to available for the reaction.
The catalyst pore size and properties are selected for enhancing
the catalyst activity/life. The special catalyst have been listed
in the later process description and are claims of the process so
as to make dual catalyst beds an art claimed by this process
together with the special selectivator/solvating agent.
[0006] The Hydrogenation is designed either to use dual catalyst
system, Nickel and followed by Palladium in the finishing reactor
(one can use either of the catalyst in both the reactors if so
desired). Provision is there to use Palladium Platinum catalyst in
the finishing Reactor as an extension of this invention.
SUMMARY OF THE INVENTION
[0007] The process in this art claims that if feed has small amount
of propylene (1 to 3%) which will be converted to isopropyl alcohol
with small amount of water and iso-octene produced in the reactor
which is taken as a bottom product in the debutanizer column. The
Isopropyl alcohol will be recycled back to the reactor so as to
have low requirement of propylene in the feed, propylene can be
reduced to about 0.5% in the Feed, based on the losses in the
process. The process in this art requires that IPA (isopropyl
alcohol) be about 0.5% to 3.0% by wt in the C.sub.4 feed to the
reactor.
[0008] The Feed is water washed to remove the basic compounds in
the feed and metal impurities especially acetonitrile which is well
known catalyst poison for the etherification ion exchange catalyst.
After the water wash, the Feed with slight amount of propylene is
heated to the reaction temperature and is mixed with stochiometric
amount of hydrogen to hydrogenate the butadiene, and mixing it with
recycle stream before sending it to the reactor. The feed is
reacted to hydrogenate the butadiene with trifunctional catalyst
and also forms the dimer in the down flow fixed bed reactor in both
beds of catalyst. The recycle stream of Isopropyl alcohol (IPA) and
the unreacted isobutylene with other C.sub.4 components in the feed
are recycled to the reactor so as to have low concentration of
isobutylene in the reactor. This provides low conversion per pass
in the reactor and it helps in having better selectivity. The 6
figures are herewith attached to describe the different
configurations to provide the best catalyst activity, yield and
selectivity.
[0009] The Isobutyelene dimerizes and produces Iso-octene and also
some side reactions takes place which produce the isomers of
Iso-octene reacting with isobutylene and other straight chain
olefins. The configurations, catalyst selection, operating
conditions are chosen to give best results for selectivity and
yield, together with enhancing the catalyst life. In the reaction
some trimer and very small amount of tetramer are also formed,
together with small amount of C.sub.8 ethers.
[0010] Similar to the etherification process, once the reaction has
taken place in the Fixed Bed Reactor or Reactors as shown in the
Figures, the reactor effluent goes to the debutanizer column, where
Iso-octene product is taken as bottom product and C.sub.4 non
reactive stream is separated as overhead product. The selectivator
(IPA) and non-reactive C.sub.4 stream can be taken as sidedraw and
C.sub.4 stream without IPA can be taken overhead. The overhead
stream is normally sent to battery limit or alkylation unit. An
alternate of this is that one can take the Isooctane and IPA in the
bottom and send these to another column (existing methanol or
alcohol column) and separate the IPA overhead and recycled to the
reactor and bottom is Iso-octene product, this is very convenient
in the case of revamp of MTBE unit. In the existing MTBE unit,
Methanol recovery column is available to do this separation. The
Methanol extractor can be used for any other use to enhance the
yield and catalyst life or is available as idle equipment. As RHT
flow sheets, show that unreacted reactantants can be recycled from
debutanizer with the selectivator, as a sidedraw, to a side reactor
or bulk catalyst can be installed in the debutanizer as shown in
the FIGS. 3 and 5, to enhance the conversion.
[0011] The advantages of the disclosed process are an art of
improved catalyst system (dual catalyst beds Resin doped with
palladium and resin catalyst Amberlyst 15 or 35 or equivalent), new
process configuration, increased catalyst life due to selective
hydrogenation butadiene and a new and improved selectivator IPA are
at the heart of the process. Additionally it is much better option
than the proprietary catalyst processes, which are expensive and
use single source supplier, and provide lower conversion and
selectivity (it as for MTBE). The RHT process has additional
advantage of simple reactor design, no cumbersome catalyst loading
requirements. The process has the advantage of changing the
catalyst while the unit is in operation. The major breakthrough is
that by recirculation of the some the side draw liquid the feed
isobutylene concentration is brought into range of one third to one
fifth of the virgin feed concentration by dilution, which provides
low conversion per pass and high selectivity. The product is sent
back to the same location from where the sidedraw was taken out
from column, so there is no effect on the debutanizer size. The
reducing per pass conversion by dilution provides longer catalyst
life and better yields and selectivity and new selectivator of
Isopropyl Alcohol are the major claims and benefit of the process.
As the boiling point difference of MTBE and Iso-octene are far
apart (about 100 F), there is no problem in separation of C4's and
the Iso-octene in the existing MTBE column if one returns the
reactor effluent at the side draw location.
[0012] The invention covers the hydrogenation of iso-octene to
iso-octane catalytically under milder conditions (lower pressure)
and using a configuration which helps to enhance the hydrogenation
due to dual catalyst system and is lower cost. The pressure and
temperature in the reactor are in the range of 250 psig to 450
psig, (preferably closure to 250 psig) and temperatures are in the
range of 200 to 500 F (preferably closure to 300 F) and hydrogen
about 1.5 to 2.0 times the stoichiometric (closure to 1.30 times)
are used in the process. The WHSV in the first reactor is in the
range of 1 to 4 (preferably close to 2 to 3) and in the finishing
reactor 3 to 6 (preferably closure to 4 to 5).
[0013] This unique feature will be apparent to one who is skilled
in the art from the figures and claims and brief description of the
figures.
BRIEF DESCRIPTION OF THE FIGURES
[0014] FIG. 1 is a simplified process flow diagram. The Feed stream
1 is washed in column 8 with water wash. The Feed stream 3 is
heated to the reaction temperature and is mixed with hydrogen and
is sent to the reactor item 9 which has dual catalyst. The feed to
the reactor is mixed with as illustrated in the figure, with the
selectivator and some of the side draw(s) or total draw(s) off
stream 7, (which have some of unreacted isobutylene) taken from the
debutanizer. This recycled stream to the reactor is provided so as
to enhance the conversion, selectivity and product yield. The side
draw quantity from the reactor is fed back to the column by stream
11 at the same location, hence this recycle products do not effect
the column size. The recycled side draw streams to the reactor
reduces the need for additional reactor and provides enhanced
conversions and yields, and with proper design there is no effect
on column and energy requirements. The C.sub.4 are taken as stream
5 from the debutanizer item 10, and Iso-octene product is taken as
stream 6. The reactor temperature is 100 to 120 F at the inlet and
140 to 150 F at the outlet of reactor and the pressure is kept at
about 100 to 175 psig and it is essential that the reaction is done
in liquid phase.
[0015] FIG. 2 is another mode of the simple process flow diagram
where again Feed stream 1 is washed with water in column 8 and
stream 3 after water wash is heated and mixed with hydrogen and is
sent to the first Reactor item 9, which is mixed with stream 12
which is recycle IPA the selectivator and some of the draw off from
stream 7. The Reactor effluent stream 4 is sent to debutanizer item
10 where C.sub.4 and iso-octene is separated. Some of C.sub.4 are
taken as draw off from the debutanizer stream 7, which are recycled
to first reactor and also to enhance the conversion are converted
in the second Reactor Item 13 and the Reactor effluent stream a4 is
sent back to the column for separation. The iso-octene together
with IPA are sent to the column where IPA is taken overhead and is
recycled to both the Reactors via stream 12 and the Iso-octene is
taken as bottom product as stream 6 and is sent to OSBL or for
hydrogenation to produce Iso-octane as shown in FIG. 6. The
configuration is similar to FIG. 1 except another reactor is added
to enhance the conversion, selectivity and yield, (similar to FIG.
1), by taking a side draw(s) from the debutanizer and this stream
is reacted in the side reactor in the presence of catalyst. The
idea here is to do the reaction and conversion under controlled
conditions so as to get the best yield and less catalyst
deactivation. As in FIG. 1 the selectivator is distributed in both
the reactors through stream 12. Additionally, the Iso-octene and
the selectivator is taken in the second column overhead product and
distributed into both the reactors. The C.sub.4 stream is taken as
overhead from the debutanizer column as stream 5 and is sent to
alkylation or LPG system
[0016] FIG. 3 is another mode of configuration to enhance the yield
and conversion and selectivity and most of the elements are similar
to FIG. 1 up to the first Reactor and the backend after the
debutanizer. The first reactor does the reaction same as in FIG. 1,
there is always IPA selectivator used in all the configurations
shown in all the Figures. To enhance the conversion bulk catalyst
can be installed in the debutanizer item 12, so that the reflux
liquid is converted to iso-octene, and the vapor is bypassed
through the chimney trays. This bulk catalyst is installed on the
Johnson Screen grid and hold down plate is used to keep the
catalyst in the debtanizer The design provides pressure balance in
the chimney tray/trays by restricting the chimney flow so that
slight liquid head is provided so as liquid to go through the
catalyst in downflow manner as is the case normally. This
restriction in chimney tray of the special nature is being claimed
by the art of this invention. There could be multiple beds in the
column but the bed height required is very small compared to the
reactive distillation application. This is bulk catalyst, so the
cost of catalyst is very low and is easy to install. Essentially
the FIG. 3 configuration is similar to FIG. 1 except installing the
bulk catalyst in the column. All the reaction is done in liquid
phase. The Reactors, which use boiling in the reactor, are not
efficient as some of the reactants go in vapor and the catalyst
utilization is not optimum.
[0017] FIG. 4 is a MTBE unit process flow diagram, which is being
converted to Iso-Octene process. The process flow diagram
modification for revamp have been shown how to modify so as to be
similar to FIG. 2, but it can be modified to be FIG. 1 or 3 easily
if so required (based on the requirements of the process) to
enhance the conversion and economics and capital investment
requirements.
[0018] FIG. 5 is the similar process flow diagram to FIG. 1 to 4,
which covers all the options. This FIG. 5 includes recycling the
Feed to first reactor, and having bulk catalyst item 12 installed
in the debutanizer column together with revamping of the Reactive
distillation column of MTBE unit at low cost, having a higher
conversions, better selectivity and catalyst life. In FIG. 4 and
FIG. 5, alcohol extractor is deleted, but to save capital cost and
to enhance the catalyst life it can be converted to iso-octene
reactor and is being claimed by this art and patent claim.
[0019] FIG. 6 is the hydrogenation of iso-octene to iso-octane. The
Iso-octene from the OSBL or directly from the debutanizer is pumped
through line 5 to the reactor pressure, it is mixed with the
recycle stream 8 which provides the dilution and heat sink, mixed
with hydrogen which is fed through line 6 and all are mixed by the
inline Mixer before feeding to the Hydrogenation Reactor through
line 7 at the reaction temperature and pressure. The Reactor
product is flashed in Drum item 2, hydrocarbon vapor are condensed
and sent back to drum. The vent is sent to fuel gas system. The
Liquid from item 2 is fed to the Finishing Reactor item 3, after
mixing with hydrogen by the inline Mixer. The Reactor effluent is
fed to the Iso-octane Stripper item 4, to stabilize it. The
Iso-octane product is taken as bottom product and cooled before
sending it to storage.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The major art and know how described here is a disclosure of
producing Iso-octene by dimerizing isobutylene in the C.sub.4
Stream from FCC, Steam Crackers, thermal crackers or on purpose
dehydrogenation units. The reaction is performed in the presence of
a new solvator/selectivator (IPA) which is helpful to keep the
catalyst in solvated form, which stops the polymerization of
olefins. The operating conditions and recycled streams are provided
so that low conversion per pass is achieved due to dilution effect,
and the total conversion of isobutylene is essentially kept to be
optimum and is more than any other process. As reaction is pretty
fast, one does not need too much of catalyst. The feed is washed
for basic compounds that are poison for the catalyst similar to
Etherification process. The present art provides a small amount of
trifunctional catalyst so as to reduce any deactivation due to
diolefins/butadiene. The dilution effect makes the process
selective, due to low conversion per pass but the conversion is
higher then the conventional processes on the fresh feed basis, the
other straight chain olefins react to a lower degree with
isobutylene under low per pass conversion, compared to other
processes. The configuration provides reaction of the straight
chain olefins lower compared to conventional scheme and the
n-olefins are good feed stock for Alkylation. The codimers produced
have lower octane than iso-octene. The catalyst used in this
process is the same Ambrlyst 15, 35, 36 and CH10, K2431, K2621,
K2629 or K2624 or equivalent. The resin catalyst doped with Pd
(CH10 or K2624) or normal palladium or Nickel catalyst for
hydrogenation is provided as dual layer bed, with WHSV with Pd
doped catalyst. Pd or Nickel catalyst of 2 to 30, preferably in the
range of 8 to 25 so as to selectively saturate the butadiene to
olefin and also stabilize the olefins in the feed. As regards to
other standard resin catalyst provided, WHSV is in the range 2 to
20, preferably in the range of 4 to 8.
[0021] The disclosed method and art can be understood by referring
to the attached figures for the individuals who are familiar with
the art, which are described in detail description of the figures
herein. It should be understood that pipelines are in fact being
designated when streams are identified and that stream are
intended, if not stated when materials are mentioned. More over,
flow control valves, temperature regulating and measuring devices,
pumps, compressors, reboilers, condensers, coolers, heaters and
drums and the like are understood as installed and operating in
conventional relationships to the major items of equipment which
are shown in the drawings and discussed hereinafter with reference
to the continuously operating process of this invention and art
there in. All of these valves, devices, pumps, and compressors, as
well as heat exchangers, accumulators, condensers and the like are
included in the term auxiliary equipment. It is also understood
that any of the equipment or reactors can be decoupled by
installing a drum in between two equipment items, so as to operate
the these equipment at different conditions. It is an ability of
ordinary skill in the art to implement such auxiliary equipment, as
needed, in view of the present disclosure.
[0022] FIG. 1 illustrates an embodiment of the disclosure process.
Iso-olefin Feed 1 should have small amount of propylene so as to
make Isopropyl alcohol (IPA) which works as a
Solvator/Selectivator. It is normal practice to wash the feed with
water or run it through adsobsent where all the impurities are
removed which deactivate the catalyst. After the water wash,
C.sub.4 Feed through line 3, is mixed with hydrogen before it is
sent to stand alone reactor 9, if dual function catalyst is being
used. Stand alone reactor 9 can be fixed bed down flow, or upflow
reactor and could have a recycle with cooler if required. If one
uses single function catalyst like Amberlyst 35, then no hydrogen
feed is required. Effluent 4 from the reactor is fed to the column
10. Heavy components like Iso-octene together with some of the IPA
goes to the bottom of the column and are taken as product through
line 6. The Lighter components e.g. other C.sub.4's and unreacted
isobutylene together with IPA goes in the top section of the column
10. Partial draw off or total draw off is taken from one or
multiple places through line 7 and after cooling is fed the first
reactor for additional conversion. So as to optimize the column
size, reactor effluent is distributed in the same proportion as was
put in through lines 4 sod 11. The dual function or single catalyst
would be used so as to meet the catalyst life.
[0023] In the embodiment illustrated in the FIG. 1, reactants are
exposed to the catalyst at low concentration due to recycle from
the column, and in doing so the selectivity and conversion achieved
are much better than the fresh Feed. If catalyst quantity provided
is adequate to have WHSV of about 4 for the combined catalyst (dual
function and single function) and the pressure and temperature are
kept at 125 psig to 150 psig and temperature of 130 to 150 F is
kept to provide optimum conversion and product quality. One has to
see that minimum of 0.5to 3% of IPA is in the reactor effluent
which is being recycled with unconverted Feed through line 7. As
shown in the FIG. 1 distillation is done to take the IPA with C4's
in the draw off and that is being recycled. The non-reactive
C.sub.4 stream and normal olefins are taken overhead. In the normal
feed very small amount of propylene in the Feed is required to make
the additional IPA, which has been lost in the bottom and overhead
streams.
[0024] FIG. 2 in this embodiment shows similar process flow diagram
as FIG. 1, C.sub.4 Feed is fed through line 1 and is washed in
water wash Column (WWC). The C.sub.4 Feed after washing, through
line 3, is mixed with hydrogen before it is sent to stand alone
reactor 9, if dual function catalyst is being used. Stand alone
reactor 9 can be fixed bed down flow, or upflow reactor and could
have a recycle with cooler if required. If one uses single function
catalyst like Amberlyst 35, then no hydrogen feed is required.
Effluent 4 from the reactor is fed to the column 10. Heavy
components like Iso-octene together with of the IPA goes to the
bottom of the column and is fed to the Iso-octene column where
product Iso-octene is taken through line 6. The lighter components
in debutanizer e.g other C.sub.4's and unreacted isobutylene is
taken as overhead product, but some of the C.sub.4's are taken as
side draw or multiple side draws through line 7 and are isobutylene
is converted to Iso-octene in side reactor(s) 13. The reaction
product from the side reactor is sent to the column where they have
withdrawn from or some other location where concentration is
similar, but without increasing the Column diameter or duties. As
shown that IPA is taken overhead in Iso-octene Column 11 as
overhead product and is recycled to both the reactor s first
reactor 9 and the sidedraw reactor 13. The dual function or single
catalyst would be used so as to meet the catalyst life and is the
claim of the invention. The operating pressure, temperature is in
the same range as mentioned in FIG. 1 above.
[0025] FIG. 3 is another variation of FIGS. 1 and 2, C.sub.4 Feed
is fed through line 1 and is washed in water wash Column (WWC). The
C.sub.4 Feed after washing, through line 3, is mixed with hydrogen
before it is sent to stand alone reactor 9, if dual function
catalyst is being used. Stand alone reactor 9 can be fixed bed down
flow, or upflow reactor and could have a recycle with cooler if
required. If one uses single function catalyst like Amberlyst 35,
then no hydrogen feed is required. Effluent 4 from the reactor is
fed to the column 10. Heavy components like Iso-octene together
with the IPA goes to the bottom of the column and is fed to the
Iso-Octene column where product Iso-octene is taken through line 6.
The lighter components in debutanizer e.g. other C.sub.4's and
unreacted isobutylene are taken as overhead product. With the
reflux some of isobutylene is reacted in the column bulk catalyst
shown as 12 (can have multiple beds). IPA is taken as overhead
product in Iso-octene Column 11, where IPA is recycled to the first
stand alone reactor 9 and also to Column bulk catalyst section 12.
These details of operating conditions and WHSV will be illustrated
in a separate section. The debutanizer catalyst 12 is provided as
bulk catalyst on the grating and Johnson screen is used to see that
catalyst does not pass through to bottom of the column. The
catalyst in the column enhances the conversion. Instead of bulk
catalyst one can provide side reactor the other conditions remain
the same as for FIGS. 1 and 2.
[0026] FIG. 4 is an embodiment in which it is shown how to revamp
the existing MTBE unit. The hatched lines and equipment are to be
deleted. Additional reactor in parallel may be required but might
not be necessary. So most of the equipment is available and some
piping modifications might be necessary. It is possible that all
the instruments are adequate. So revamp cost are very low.
Operating conditions and catalyst requirements are as for FIG. 1, 2
and 3. In FIG. 4, C.sub.4 Feed is fed through line 1 and is washed
in water wash Column (WWC). The C.sub.4 Feed after washing, through
line 3, is mixed with hydrogen before it is sent to stand alone
reactor 9, if dual function catalyst is being used. Stand alone
reactor 9 can be fixed bed down flow, or upflow reactor and could
have a recycle with cooler if required. If one uses single function
catalyst like Amberlyst 35, then no hydrogen feed is required.
Effluent 4 from the reactor is fed to the column 10. Heavy
components like Iso-octene together with of the IPA goes to the
bottom of the column and is fed to the Existing Methanol recovery
column (Iso-octene column) where product Iso-octene is taken
through line 6. The lighter components in debutanizer e.g. other
C.sub.4's and unreacted isobutylene is taken as overhead product
through line 5, but some of the C.sub.4's are taken as side draw or
multiple side draws through line 12 and isobutylene is converted to
Iso-octene in side reactor(s) 13 which is existing finishing MTBE
reactor but has to be repiped. The reaction product from the side
reactor is sent to the column where they have withdrawn from or
some other location where concentration is similar, but without
increasing the Column diameter or duties. As shown that IPA is
taken overhead in Iso-octene Column 11 as overhead product through
line 7, and is recycled to both the reactors, first reactor 9 and
the side draw reacror 13 through line 14. The dual function or
single catalyst would be used so as to meet the catalyst life and
is the claim of the invention. The operating pressure, temperature
is in the same range as mentioned in FIG. 1 above. Naturally the
Methanol feed system and the methanol Extractor 15 can be used for
alternate use in the unit to enhance yield and catalyst life.
[0027] FIG. 5 is illustrates an embodiment in which it is shown how
to revamp the Reactive distillation MTBE unit to Iso-octene unit.
The hatched lines and equipment are to be deleted. Additional
reactor in parallel may be required but might not be necessary. So
most of the equipment is available and some piping modifications
might be necessary. It is possible that all the instruments are
adequate. So revamp cost are very low. Operating conditions and
catalyst requirements are similar to as for FIGS. 1, 2 and 3. In
FIG. 4, C.sub.4 Feed is fed through line 1 and is washed in water
wash Column (WWC). The C.sub.4 Feed after washing, through line 3,
is mixed with hydrogen before it is sent to stand alone reactor 9,
if dual function catalyst is being used. Stand alone reactor 9 can
be fixed bed down flow, or upflow reactor and could have a recycle
with cooler if required. If one uses single function catalyst like
Amberlyst 35, then no hydrogen feed is required. Reactor effluent
through line 4 is fed to the column 10. Heavy components like
Iso-octene together with of the IPA goes to the bottom of the
column and is fed to the Existing Methanol recovery column
(Iso-octene column) where product Iso-octene is taken through line
6. The lighter components in debutanizer e.g. other C.sub.4's and
unreacted isobutylene is taken as overhead product through line 5,
but some of the C.sub.4's are taken as side draw or multiple side
draws (not shown) and are recycled to the first reactor to reduce
the conversion per pass, enhancing isobutylene conversion to
Iso-octene in side reactor 9 which is existing first MTBE reactor
but has to be repiped. The reflux in the column can be converted by
installing bulk catalyst in the column as suggested in FIG. 3 or
can be repiped as side reactors as shown in FIG. 2. Reaction
product from the side reactor is sent to the column where they have
withdrawn from or some other location where concentration is
similar, but without increasing the Column diameter or duties. As
shown that IPA is taken overhead in Iso-otene Column 11 as overhead
product through line 7 and is recycled to both the reactor s first
reactor 9 and the side Draw reactors through line 15 and some to
the bulk catalyst in the column, reaction zone if required, though
this might not be required. The dual function or single function
catalyst would be used so as to enhance the catalyst life and is
one of the claims of the invention. The operating pressure,
temperature is in the same range as mentioned in FIG. 1 above.
Naturally the Methanol feed system and the methanol Extractor 14,
can be used for alternate use in the unit to enhance yield and
catalyst life.
[0028] Individuals familiar with the skill in the art do understand
the importance of removing the basic compounds by Feed water wash
system. After water wash, the second major art in Iso-octene
Technology is to have), 0.05 to 2.5% of Solvator/selectivator in
catalyst (alcohol) with the Feed to provide good catalyst life and
low polymerization. Here selectivator being used is Isopropyl
Alcohol, and any other compound if they are boiling in that range
will also recycle which can not be helped. The third art in this
embodiment is being used is to have tri-functional catalyst at a
very high WHSV (15 to 25), so as to see that the diolefins do not
polymerize on catalyst. The other major art in the embodiment is
reduce the conversion per pass in the reactor, which enhances the
catalyst life and selectivity. The art has already been described
so as to be able to use the existing column size by putting the
recycle stream flows to at the same location from where these were
so that there is no effect on debutanizer design compared to
conventional processes. As C.sub.4 and C.sub.8 separation is pretty
easy there is no problem in achieving this concept. The last but
not the least is the selection of right catalyst and we will here
suggest catalyst, which we claim, will provide optimum conversion
and yield.
[0029] One of the major skill in the art is to have the clean feed
devoid of basic compounds, right catalyst selection, selectivator
and per pass conversion to be reduced. The process is for
dimerizing the Isobutylene, but it also reacts with some straight
chain olefins, which provides isomers with slightly lower octane.
The reaction products are sent to the debutanizer where Iso-octane
is separated from C.sub.4 stream. Iso octene with other byproducts
is sent to existing Methanol recovery column or new column to
separate the selectivator and recycle it to the reactor. The bottom
product is Iso octene with very good octane and can be hydrogenated
to provide Iso-octane, which will provide the product, which will
reduce the olefins, concentration in the gasoline pool.
[0030] All the figures show that unreacted feed can be recycled to
the first reactor and isobutylene there in would be converted to
iso-octene or codimers. It will be diluted as well so the
conversion per pass will go down and quality will be good. No doubt
the selectivator will be recycled either from this debutanizer or
after separating in a second column. The other Option is by putting
the side reactors conversion can be enhanced , but the recycle to
the first reactor be still kept so as to have low per pass
conversion, this is one of the major claim of the process. The
column size will not be effected, as the products will be fed at
the same location from where they are withdrawn. C.sub.4 and
iso-octene separations not difficult so there is no problem in
separation and keeping the per pass conversion low in the reactor
which provides better selectivity and catalyst life as well.
[0031] Alternatively, the catalyst can be installed in the column
as bulk catalyst on a grating with Johnson Screen and a holddown
grid, with chimneys for by passing the vapor. There could be more
than single bed (multiple beds) and similarly the side reactor can
be more than one to enhance the conversion, only major requirement
is to keep the conversion low in the reactors and that enough
selectivator is there so as to provide the catalyst solvated.
Reactions stages can be as desired but normally in this
application, two reaction stages will provide the economical
conversion of about 95 to 99 wt % isobutylene.
[0032] In this patent, selectivator/solvator which is being used is
Isopropyl Alcohol and any other compounds which boil at the same or
close boiling compounds will automatically go with IPA and will be
recycled to the reactor. The single pass conversion is to kept low
so as to get the best selectivity.
[0033] The reaction is done around 100 degrees F. to 160 degrees F.
and the reactor pressures are kept at around 95 to 150 psig. The
catalyst used is Amberlyst CH10 (palladium or Nickel catalyst for
selective hydrogenation, plus Amberlyst 35 or 36, or one can use
Lewatit K 2624 plus K 2431 or SP 112-H or equivalent Catalyst in
resin family or zeolyte family but not limited to these catalyst or
any catalyst which provides acidity for the reaction and the proper
properties is acceptable and will be used. The dual catalyst system
is claimed by the art in this process as selective hydrogenation is
mandatory for the process to enhance the catalyst life, but if one
is prepare to sacrifice the catalyst, than one can operate the unit
without selective hydrogenation.
[0034] Examples of suitable selectivator/solvators could be any
alcohol which boils below the Iso-octene so that it can be recycled
to the reactor. Here RHT process has come up with an IPA
selectivator, which is formed by hydration of propylene in Feed and
small quantity of water, which are normally available in the feed
with the same resin or acidic catalyst.
[0035] The first reactor operates at about 95 to 175 psig and 100
degrees F. to 190 degrees F. in the presence of above mentioned
catalyst, together with selectivator and dilution so as to reduce
the per pass conversion. The iso-olefin (isobutylene) in the Feed
can be say from 7% to 60 percent in the C.sub.4 feed stream. The
high concentration feeds need careful consideration but the
advantages is that some of these Feeds don't have basic compounds
and also other olefins are in small quantity so the catalyst life
and selectivity can be maintained if heat of reaction or per pass
reaction is properly controlled.
[0036] 95 to 99 wt % isobutylene conversions can be easily achieved
with a reasonably high Octane product. The selectivity can be kept
good so that boiling range of the product is similar to the
gasoline boiling range. It is expected that 97 to 99 percent
isobutylene is converted, and normal butylenes are converted from
10 to 25%. The product is expected to be about 80 to 90% C.sub.8
olefins and 10 to 20% of C12 Olefins with 0.1 to 1.0% of C16
olefins. But selectivity is much better than most of the processes
available in the market due to reduced per pass conversion and
lower temperature. Higher temperature and vapor in the reactor
provides lower selectivity and conversion so reactor is operated in
liquid phase as desired by the reaction kinetics.
[0037] In the embodiment of this patent, art is illustrated that
one can get high conversions with one reactor, side reactors, by
installing catalyst in the column, and there are advantages of each
configuration to keep the conversion low by diluting the feed with
recycle which provides high selectivity. For the most of cases,
where this application will be applied be first to the existing
MTBE units after that one will consider the on purpose MTBE
merchant units and there is real advantage in realizing this once
the MTBE is phased out. As shown in the FIG. 4 and 5, RHT process
with very little additional Capital cost can revamp the
conventional or reactive distillation MTBE units.
[0038] The major invention in this embodiment is that using the IPA
selectivator. Dual catalyst to stabilize the feed and reduce the
butadiene by selective hydrogenation of the feed, provide dilution
to reduce the conversion per pass which improves the selectivity
and catalyst life and reduces the exotherm in the reactor, provide
side reactors to enhance the conversion or by installing bulk
catalyst in the column by providing vapor bypass of the bed with
chimney trays. These are the major claims of this invention for
producing Iso-octene.
EXAMPLES
[0039] The following example illustrates the feeds which could be
used for making Iso-octene. These could be from multiple sources
FCC C.sub.4 Stream, Steam Cracker C.sub.4 Stream and on purpose
Isobutane Dehydrogenation units, which can provide good feed for
Iso-octene production. The higher concentration feeds need is well
suited to this configuration.
TABLE-US-00001 C.sub.4 Feed from the FCC unit: Component wt %
Propane 1.2 Propylene 0.7 Isobutane 23.9 Isobutylene 17.8 1-Butene
13.7 c-2-butene 12.6 t-2-butene 14.3 n-butane 15.3 C.sub.5's 0.5
Total 100.00 Iso-octene Product C.sub.8 olefins 90 to 92% C.sub.12
Olefins 7.5 to 9.0% Other byproducts 0.5 to 2.0% Iso-octane Product
C.sub.8 Paraffins 91 to 93% C.sub.12 Paraffins 7 to 8.5% Other
impurities 0.5 to 2.0%
[0040] The following reaction conditions and yields can be expected
from this unit:
Based on the configuration and feed compositions following
conditions will be required for the first and Side reactors
configuration: [0041] Inlet Temp (F) 100 to 180 (100 to 130 F
preferable) [0042] Pressure (psig) 100 to 175 [0043] LHSV
(hr).sup.-1 3 to 6 [0044] Iso-olefin Conversion (%) 97 to 99%
(overall) [0045] n-olefin Conversion: Minimize the olefin
conversion to Codimers
[0046] Reaction Chemistry
Iso-octene Reactions:
[0047] 2 Isobutylene.fwdarw.Iso-octene [0048]
Isobutylene+n-butykene.fwdarw.Codimers [0049]
Isobutylene+iso-octene.fwdarw.C.sub.12 olefins [0050]
Iso-octene+Iso-octene.fwdarw.C.sub.16 olefins [0051]
Alcohol+olefins.fwdarw.C.sub.8 Ethers
Iso-octane Reactions:
[0051] [0052] C.sub.8 olefins+H.sub.2.fwdarw.C.sub.8 Paraffin
[0053] C.sub.12 olefins+H.sub.2.fwdarw.C.sub.12 Paraffin [0054]
C.sub.16 olefins+H.sub.2.fwdarw.C.sub.16 Paraffin
* * * * *