U.S. patent application number 12/095127 was filed with the patent office on 2009-01-01 for method for producing olefins from synthesis gas in a reaction column.
This patent application is currently assigned to BASF SE. Invention is credited to Jochen Burkle, Thomas Butz, Bram Willem Hoffer, Gerd Kaibel, Dirk Neumann, Ekkehard Schwab.
Application Number | 20090005464 12/095127 |
Document ID | / |
Family ID | 37774573 |
Filed Date | 2009-01-01 |
United States Patent
Application |
20090005464 |
Kind Code |
A1 |
Hoffer; Bram Willem ; et
al. |
January 1, 2009 |
Method for Producing Olefins from Synthesis Gas in a Reaction
Column
Abstract
Process for the synthesis of olefins from synthesis gas in the
presence of at least one Fischer-Tropsch catalyst in a reaction
column, wherein the synthesis gas is introduced into the reaction
column below a zone A of the reaction column and the olefins formed
are taken off below the inlet for the synthesis gas.
Inventors: |
Hoffer; Bram Willem;
(Heidelberg, DE) ; Schwab; Ekkehard; (Neustadt,
DE) ; Kaibel; Gerd; (Lampertheim, DE) ;
Neumann; Dirk; (Ladenburg, DE) ; Burkle; Jochen;
(Mannheim, DE) ; Butz; Thomas; (Mannheim,
DE) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
BASF SE
Ludwigshafen
DE
|
Family ID: |
37774573 |
Appl. No.: |
12/095127 |
Filed: |
November 23, 2006 |
PCT Filed: |
November 23, 2006 |
PCT NO: |
PCT/EP06/68780 |
371 Date: |
May 28, 2008 |
Current U.S.
Class: |
518/715 ;
518/728 |
Current CPC
Class: |
B01D 3/009 20130101;
C10G 2/00 20130101 |
Class at
Publication: |
518/715 ;
518/728 |
International
Class: |
C10G 2/00 20060101
C10G002/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2005 |
DE |
10 2005 056 784.3 |
Claims
1-14. (canceled)
15. A process for the synthesis of olefins from synthesis gas in
the presence of at least one Fischer-Tropsch catalyst in a reaction
column, wherein the synthesis gas is introduced into the reaction
column below a zone A of the reaction column and the olefins formed
are taken off below the inlet for the synthesis gas, wherein the
zone A comprises at least one combined reaction and distillation
zone (combination zone).
16. The process according to claim 15, wherein the Fischer-Tropsch
catalyst is localized in the reaction zone.
17. The process according to claim 15, wherein the Fischer-Tropsch
catalyst is localized in the combination zone.
18. The process according to claim 15, wherein the zone A comprises
at least one combination zone and at least one physically separate
distillation zone.
19. The process according to claim 15, wherein the zone A comprises
at least one physically separate reaction zone and distillation
zone.
20. The process according to claim 15, wherein the olefins are
.alpha.-olefins.
21. The process according to claim 15, wherein the olefins formed
are taken off via the bottom zone of the reaction column.
22. The process according to claim 15, wherein synthesis gas is
introduced at one or more points within the zone A in addition to
the introduction of synthesis gas below the zone A.
23. The process according to claim 15, wherein the catalyst forms a
fixed bed, a fluidized bed, a suspension or a bubble column in a
reaction or combination zone.
24. The process according to claim 15, wherein the Fischer-Tropsch
catalyst comprises at least one metal of group VIIIB.
25. The process according to claim 15, wherein an .alpha.-olefin or
a mixture of .alpha.-olefins whose number of carbon atoms is at
least 1 less than that of the olefin mainly formed which is
separated off below the zone A is introduced into the zone A during
start-up of the reaction.
26. A mixture of olefins obtainable by the processes according to
claim 15.
Description
[0001] The present invention relates to a process for the synthesis
of olefins from synthesis gas in the presence of at least one
Fischer-Tropsch catalyst in a reaction column.
[0002] The preparation of hydrocarbons from synthesis gas, i.e. a
mixture of carbon monoxide and hydrogen, has been intensively
researched for decades. This type of reaction is usually referred
to as Fischer-Tropsch synthesis. Catalysts which are usually used
in this reaction usually comprise metals of group VIIIB of the
Periodic Table, in particular Fe, Co, Ni and/or Ru, as
catalytically active metals (e.g. v. d. Laan et al. Catal.
Rev.-Sci. Eng., 41, 255 (1999)).
[0003] Despite the intensive research activities hitherto, there is
a need to optimize Fischer-Tropsch processes further. It is known
that the product compositions, whose component can range from
methane through higher alkanes, higher alkenes, etc., to aliphatic
alcohols can be altered as a function of the chosen reaction
conditions, the catalysts, etc. In addition, the exothermic nature
of the Fischer-Tropsch process makes handling and in particular
control of the reaction difficult.
[0004] If hydrocarbons enriched with olefins, preferably with
.alpha.-olefins, are to be prepared, the catalysts used are
generally ones which comprise nickel, cobalt, iron or ruthenium, in
particular iron, iron and cobalt, iron/cobalt spinel or
cobalt/manganese spinel, and also copper-promoted cobalt
catalysts.
[0005] GB 1 512 743, GB 1 553 361, GB 1 553 362 and GB 1 553 363
describe catalytic processes for the synthesis of unsaturated
hydrocarbons from synthesis gas at from 250 to 350.degree. C. and
from 10 to 30 bar. The catalysts used here comprise [0006] (a) one
or more oxides of the "difficult-to-reduce" metal oxides of group
IVB of the Periodic Table or a lower oxide of a transition metal of
group V or VII of the Periodic Table; and [0007] (b) one or more
metals of group VII of the Periodic Table. These catalysts can
further comprise an alkali metal (group 1A of the Periodic Table),
magnesium oxide or zinc oxide as promoters.
[0008] U.S. Pat. No. 4,199,523 discloses a Fischer-Tropsch catalyst
which comprises at least 60% of iron. Furthermore, this catalyst
can comprise promoters such as copper, silver or alkali metals
and/or other additives such as zinc oxide, manganese oxide, cerium
oxide, vanadium oxide and chromium oxide.
[0009] In U.S. Pat. No. 4,418,155, Chang et al describe a process
for the conversion of synthesis gas into hydrocarbons enriched with
linear .alpha.-olefins, by bringing the synthesis gas at from about
260 to 345.degree. C. into contact with a catalyst comprising a
ZSM-5 type zeolite on which metals such as iron, cobalt or
ruthenium have been deposited.
[0010] Furthermore, U.S. Pat. No. 5,100,856 describes
copper/potassium-promoted iron/zinc catalysts which display
improved activity, selectivity and stability in the synthesis of
.alpha.-olefins from carbon monoxide and hydrogen.
[0011] It is likewise known that the composition of the
hydrocarbons formed in the Fischer-Tropsch process can be strongly
influenced by the choice of the catalysts used, the types of
reactor and the reaction conditions.
[0012] WO 02/092216 describes, for example, a Fischer-Tropsch
process over a monolithic catalyst support in a reactor which is
divided into a plurality of reaction chambers in which the chemical
reaction and the physical separation of the products take place.
The product streams which are discharged from the various chambers
differ in terms of their composition. For example, gasoline,
kerosene and diesel are discharged separately from the reactor in
the present case.
[0013] Despite the improvements which have been achieved to date,
there continues to be a need for improvement of the commercially
operated Fischer-Tropsch plants for the synthesis of olefins having
from 4 to 20 carbon atoms.
[0014] It is an object of the present invention to provide a
process for the synthesis of olefins, in particular
.alpha.-olefins, from synthesis gas.
[0015] The object of the present invention is achieved by a process
for the synthesis of olefins from synthesis gas in the presence of
at least one Fischer-Tropsch catalyst in a reaction column, wherein
the synthesis gas is introduced into the reaction column below a
zone A of the reaction column and the olefins are taken off below
the point at which the synthesis gas is fed in.
[0016] The reaction column used in the process of the invention
comprises at least one top zone, a zone A and a bottom zone. Top
zone, zone A and bottom zone are arranged in the stated order from
the top downward in the reaction column. The zone A comprises at
least one reaction zone and a distillation zone. The synthesis gas
is introduced below the zone A but above the bottom zone and the
olefins are taken off below the point at which the synthesis gas is
fed in.
[0017] The Fischer-Tropsch catalyst is localized in the reaction
zone and the Fischer-Tropsch synthesis takes place there.
[0018] The fractional distillation of the products formed in the
Fischer-Tropsch synthesis takes place in the distillation zone.
[0019] However, it can also be the case that the zone of the
chemical reaction and the zone of the physical separation
(fractional distillation) are not physically separate. In this
case, a combination zone is present. The combination zone is thus a
combined reaction and distillation zone.
[0020] In the process of the invention, the synthesis gas is
introduced into the reaction column below the zone A. The synthesis
gas then comes into contact with the Fischer-Tropsch catalyst and a
first hydrocarbon mixture a is formed; unreacted synthesis gas and
volatile components of the hydrocarbon mixture formed then ascend
into the next reaction zone where a further Fischer-Tropsch
reaction takes place and a hydrocarbon mixture b is formed; this
process is repeated. On the other hand, the volatility of the
hydrocarbons formed decreases with increasing chain length and they
are then present in liquid form and flow downward into the reaction
zone(s) located underneath; there, chain extension by means of
synthesis gas present can again take place; this process, too, is
repeated. This finally results in a hydrocarbon mixture which can
be taken off below zone A. This hydrocarbon mixture has, depending
on the synthesis gas used, the Fischer-Tropsch catalyst and the
process parameters (e.g. geometry of the reaction column,
temperature profile of the reaction column, pressure, etc.), a
particular molar mass distribution and a particular mean molecular
weight. This molar mass distribution is preferably narrower than
those of conventional Fischer-Tropsch hydrocarbons.
[0021] The process of the invention thus makes it possible to set
firstly the mean molecular weight of the hydrocarbon mixture formed
and secondly its molecular weight distribution by means of the
superposition of the Fischer-Tropsch process on the distillation
process. Furthermore, a higher selectivity to the desired reaction
products, i.e. to olefins, in particular .alpha.-olefins, is
achieved.
[0022] In one embodiment of the zone A, reaction and distillation
zones alternate.
[0023] In a further embodiment of the zone A, combination and
distillation zones alternate.
[0024] In a further embodiment of the zone A, a single combination
zone is present.
[0025] In a further embodiment, synthesis gas is introduced at one
or more points within the zone A in addition to the introduction of
synthesis gas below the zone A. In some cases, it can be
advantageous to carry out the additional introduction(s) into the
distillation zone(s). However, it is also possible to carry out the
introduction(s) into combination zone(s).
[0026] In a further embodiment, water in liquid form is fed in
above or within the zone A.
[0027] However, it can also be advantageous to feed in water vapor
below or within the zone A.
[0028] In a further embodiment, the Fischer-Tropsch catalyst which
is localized in the reaction or combination zone forms a fixed bed,
a fluidized bed, a suspension or a bubble column, preferably a
fixed bed or a bubble column.
[0029] These embodiments can be implemented in a manner known per
se to those skilled in the art, by, for example, applying the
Fischer-Tropsch catalyst onto trays having a particular residence
time of the condensate, for example valve trays, bubble cap trays
or related constructions such as tunnel trays or Thormann trays, or
fixing it on them as a catalyst bed.
[0030] However, it is also possible to introduce the
Fischer-Tropsch catalyst into the column in the form of packing
elements such as Raschig rings, Pall rings, saddle bodies
appropriately provided with catalyst. Furthermore, it is possible
to use packings comprising Fischer-Tropsch catalyst or to use mesh
bags filled with Fischer-Tropsch catalyst, known as bales or Texas
teabags. The packings as such are usually made of sheet metal,
expanded metal, wire meshes or knitted meshes which preferably have
a cross-channel structure. In these cases, combination zones are
generally formed.
[0031] Internals having a distillative separation action are used
in the distillation zones of the zone A. This can be achieved, for
example, by means of trays, for example valve trays, bubble cap
trays or related constructions, e.g. tunnel trays or Thormann
trays, or sieve trays. However, it is also possible to use packings
which usually comprise sheet metal, expanded metal, wire meshes or
knitted meshes and preferably have a cross-channel structure.
Examples are the packings Sulzer MELAPAK, Sulzer BX, Montz B1 types
or Montz A3 types. However, it is also possible to use disordered
packing elements, e.g. Raschig rings, Pall rings, saddle bodies,
etc.
[0032] Preference is given to using reaction columns in which the
zone A has from 5 to 150 trays, preferably from 15 to 100 trays,
for carrying out the process of the invention.
[0033] A distillation zone usually comprises from 1 to 30 trays, a
reaction zone usually comprises one tray and a combination zone
usually comprises from 1 to 5 trays. This applies particularly when
the reaction and distillation zones or the combination and
distillation zones alternate.
[0034] In a further embodiment, a combination zone comprises from
20 to 100 trays.
[0035] A similar situation applies to the theoretical plates in the
case of other column internals, i.e. when packings, etc., are
used.
[0036] In a further embodiment, a reaction zone which is provided
with packings or with Fischer-Tropsch catalysts in the form of
packing elements provided with catalyst or with active distillation
packings or with mesh bags filled with Fischer-Tropsch catalyst
comprises from 20 to 100 theoretical plates.
[0037] In a particular embodiment, the zone A comprises from one to
three distillation zones each having from 10 to 100 trays.
[0038] In a further particular embodiment, the zone A comprises a
combination zone.
[0039] In a further embodiment, low boilers can be taken off via
the top zone of the reaction column. These low boilers generally
comprise inert gases such as nitrogen which may be present in the
synthesis gas and also any carbon dioxide formed, low-boiling
paraffins, in particular methane, low-boiling olefins such as
ethene, etc.
[0040] In a further embodiment, low boilers formed, which comprise,
for example, any low-boiling paraffins formed, low-boiling olefins
and/or water, are taken off from zone A via a side offtake. The
liquid product taken off via the side offtake can consist of two
phases. It is possible for a phase separation to be carried out and
the organic phase to be recirculated to the column. In this way,
water can be specifically removed from the reaction zone.
[0041] In a further embodiment of the reaction column, the
hydrocarbon mixture formed is removed from the reaction column
below the point at which the synthesis gas is fed in. This can be
achieved via a side offtake. However, it is also possible to take
off the hydrocarbon mixture formed via the bottom of the
column.
[0042] In a further embodiment, part of the hydrocarbon mixture
formed is taken off from zone A via a side offtake and the other
part of the hydrocarbon mixture formed is taken off below the point
at which the synthesis gas is fed in.
[0043] In a further embodiment, the reaction column used comprises
a top zone, a zone A and a bottom zone.
[0044] In a further embodiment, the reaction column used comprises
a top zone, a zone A and a bottom zone and also a distillation zone
B which is localized between the zone A and the bottom zone.
Internals having a distillative separation action can be installed
or packings can be comprised in this distillation zone. The
embodiments of the internals or packings are analogous to those of
the distillation zones of the zone A.
[0045] In a further embodiment, the reaction column used comprises
a top zone, a zone A and a bottom zone and also a distillation zone
C which is localized between the top zone and the zone A. Internals
having a distillative separation action can be installed or
packings can be comprised in this distillation zone. The
embodiments of the internals or packings are analogous to those of
the distillation zones of the zone A.
[0046] In a further embodiment, the reaction column used comprises
a top zone, a zone A and a bottom zone and also a distillation zone
B which is localized between the zone A and the bottom zone and a
distillation zone C which is localized between the top zone and the
zone A. Internals having a distillative separation action or
packings can be comprised in these distillation zones B and C. The
embodiments of the internals or packings are analogous to those of
the distillation zones of the zone A.
[0047] The synthesis gas used in the process of the invention can
be produced by generally known processes (as described, for
example, in Weissermel et al., Industrial Organic Chemistry,
Wiley-VCH, Weinheim, 2003, 15-24), for example reaction of coal or
methane with steam or by comproportionation of methane with carbon
dioxide. It usually has a ratio of carbon monoxide to hydrogen of
from 3:1 to 1:3. Preference is given to using a synthesis gas which
has a mixing ratio of carbon monoxide to hydrogen of from 1:0.5 to
1:2.5.
[0048] As catalysts, use is made of those Fischer-Tropsch catalysts
which preferentially catalyze the formation of olefins, in
particular .alpha.-olefins. Possible catalysts here are, in
particular, Fischer-Tropsch catalysts comprising iron, iron and
cobalt, iron/cobalt spinel or cobalt/manganese spinel and also
copper-promoted cobalt Fischer-Tropsch catalysts. In particular,
the catalysts described in GB 1 512 743, GB 1 553 361, GB 1 553
362, GB 1 553 363, U.S. Pat. No. 4,199,523, U.S. Pat. No.
4,418,155, U.S. Pat. No. 5,100,856 are incorporated by reference
into the present invention.
[0049] The process of the invention is usually carried out at from
150 to 350.degree. C. The pressure here is from 1 to 60 bar,
preferably from 10 to 50 bar.
[0050] The GHSV (gas hourly space velocity) is generally from 100
to 30 000 parts by volume of feed stream per part by volume of
catalyst and hour (l/lh).
[0051] The product obtained in the process of the invention, which
is removed from the reaction column below the point at which the
synthesis gas is fed in, is a mixture of a plurality of
hydrocarbons. This mixture has a particular mean molar mass and a
particular molecular weight distribution. This product preferably
comprises at least 50% by weight of olefins, preferably
.alpha.-olefins.
[0052] The olefins obtained generally have from 4 to 20 carbon
atoms, preferably from 5 to 14.
[0053] In a particular embodiment, a product comprising at least
50% by weight of olefins having from 5 to 7 carbon atoms, of which
in turn at least 50% by weight is made up of one or more
.alpha.-olefins, in particular 1-pentene and 1-hexene, is
obtained.
[0054] In a further particular embodiment, a product comprising at
least 50% by weight of olefins having from 8 to 14 carbon atoms, of
which in turn at least 50% by weight is made up of one or more
.alpha.-olefins, is obtained. These products obtained by the
process of the invention are novel.
[0055] In a further particular embodiment, a product comprising at
least 50% by weight of olefins having from 15 to 20 carbon atoms,
of which in turn at least 50% by weight is made up of one or more
.alpha.-olefins, is obtained. These products obtained by the
process of the invention are novel.
[0056] Furthermore, it can be advantageous to introduce an
.alpha.-olefin or a mixture of .alpha.-olefins whose number of
carbon atoms is at least 1 less than that of the olefin mainly
formed which can be separated off below the zone A into the zone A
of the reaction column during start-up of the process.
* * * * *