U.S. patent number RE42,832 [Application Number 10/616,797] was granted by the patent office on 2011-10-11 for method for reforming organics into shorter-chain unsaturated organic compounds.
This patent grant is currently assigned to Quantum Catalytics, L.L.C.. Invention is credited to Thomas P. Griffin, Thomas A. Kinney, Christopher J. Nagel, Kevin A. Sparks.
United States Patent |
RE42,832 |
Nagel , et al. |
October 11, 2011 |
**Please see images for:
( Certificate of Correction ) ** |
Method for reforming organics into shorter-chain unsaturated
organic compounds
Abstract
A method is disclosed for reforming organics into shorter-chain
unsaturated organic compounds. A molten metal bath is provided
which can cause homolytic cleavage of an organic component of an
organic-containing feed. The feed is directed into the molten metal
bath at a rate which causes partial homolytic cleavage of an
organic component of the feed. Conditions are established and
maintained in the reactor to cause partial homolytic cleavage of
the organic component to produce unsaturated organic compounds, as
products of the homolytic cleavage, which are discharged from the
molten metal bath.
Inventors: |
Nagel; Christopher J. (Wayland,
MA), Griffin; Thomas P. (Kennett Township, PA), Kinney;
Thomas A. (Boston, MA), Sparks; Kevin A. (Scituate,
MA) |
Assignee: |
Quantum Catalytics, L.L.C.
(Fall River, MA)
|
Family
ID: |
22628300 |
Appl.
No.: |
10/616,797 |
Filed: |
July 10, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
08172579 |
Dec 23, 1993 |
6258988 |
Jul 10, 2001 |
|
|
Current U.S.
Class: |
585/241; 585/638;
585/637; 585/541; 585/942; 208/406; 585/650; 585/634; 585/943;
208/404; 208/126; 585/648; 585/653; 585/912 |
Current CPC
Class: |
C07C
4/00 (20130101); C07C 4/10 (20130101); C10G
3/44 (20130101); C10G 1/02 (20130101); C07B
37/06 (20130101); C07C 4/10 (20130101); C07C
11/04 (20130101); C10G 2300/802 (20130101); Y10S
585/943 (20130101); C10G 2300/1011 (20130101); C10G
2300/1096 (20130101); Y10S 585/912 (20130101); Y10S
585/942 (20130101) |
Current International
Class: |
C10G
9/34 (20060101); C07C 4/02 (20060101); C07C
2/88 (20060101) |
Field of
Search: |
;585/241,541,634,637,638,648,650,653,912,942,943 ;588/201
;266/242,217,265,268 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1618182 |
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Dec 1970 |
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DE |
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2058553 |
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Feb 1974 |
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DE |
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0 067 491 |
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Dec 1982 |
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EP |
|
936899 |
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Sep 1963 |
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GB |
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44-11648 |
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May 1969 |
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GB |
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1270074 |
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Apr 1972 |
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GB |
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1350612 |
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Apr 1974 |
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GB |
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2088893 |
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Jun 1982 |
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GB |
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399526 |
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Sep 1993 |
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GB |
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93/02751 |
|
Feb 1993 |
|
WO |
|
Other References
Adams et al., "Dehydrogenation and Coupling Reactions in the
Presence of Iodine and Molten Salt Hydrogen Iodide Acceptors,"
Journal of Organic Chemistry, 42(1) :1-6 (1977). cited by other
.
Saito et al., "Dehydrogenation of Some Alcohols by the Molten Metal
Catalysts," Bulletin of the Japan Petroleum Institute, 14(2)
:169-173 (1972). cited by other .
Kashiwadate et al., "The Dehydrogenation of Butyl Alcohols by the
Molten-metal Catalysts," Bulletin of the Chemical Society of Japan,
44(11) :3004-3009 (1971). cited by other .
Haggin, J., "Growth and Dissociation of Metal-Carbon Nanocrystals
Probed," Chem. & Eng. News, pp. 29-32, Oct. 25, 1993. cited by
other .
Haggin, J., "European Conference Draws Attention to Fundamental
Role of Catalysis," Chem & Eng. News, pp. 26-30, Oct. 18, 1993.
cited by other .
Layman, P.L., "Advances in Feedstock Recycling Offer Help with
Plastic Waste," Chem & Eng. News, pp. 11-14, Oct. 4, 1993.
cited by other .
Satterfield, C.N., "Acid and Zeolite Catalysts," In Gail F. Nalven
(Ed.), Heterogeneous Catalysis in Industrial Practice, 2nd Ed.,
(NY: McGraw-Hill), pp. 209-266, pp. 339-417, (1991). cited by other
.
Jebens, A.M., "CEH Marketing Research Report, Ethylene," Chemical
Economics Handbook--SRI International, (Report Olefins 432.000 A)
Sep. 1992. cited by other.
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Primary Examiner: Dang; Thuan Dinh
Attorney, Agent or Firm: Elmore, Esq.; Carolyn S. Vanstone,
Esq.; Darlene A. Elmore Patent Law Group
Claims
What is claimed is:
1. A method for reforming hydrocarbons into shorter-chain
unsaturated organic compounds, comprising the steps of: a)
providing a molten metal bath, said molten metal bath consisting
essentially of an elemental metal which can cause cleavage of at
least one carbon-carbon bond of a hydrocarbon component of a
hydrocarbon-containing feed; b) directing said feed into the molten
metal bath at a rate which causes the concentration of carbon in
the molten metal bath to be lower than the saturation limit for
carbon of said bath at the operating conditions of said molten
metal bath, whereby the hydrocarbon component of the feed can
exhibit cleavage of at least one carbon-carbon bond of the
hydrocarbon component of said feed; and c) establishing and
maintaining conditions in said molten metal bath to cause cleavage
of at least one carbon-carbon bond of the hydrocarbon component to
produce unsaturated organic compounds, as products of said
cleavage.
2. A method of claim 1 wherein the molten metal bath includes a
transition metal component.
3. A method of claim 1 wherein the molten metal bath provided has a
melting point of greater than about 500.degree. C.
4. A method of claim 1 wherein the molten metal bath provided has a
metal equilibrium carbon solubility of greater than about 0.01% by
weight.
5. A method of claim 1 wherein the hydrocarbon-containing feed is
directed into the molten metal bath at a rate which causes the
residence time of a carbon component of the feed to be greater than
that required to cause the molten metal bath to dissolve said
carbon under the operating conditions established and maintained in
the molten metal bath.
6. A method of claim 5 wherein the hydrocarbon component of said
feed includes an alkyl compound.
7. A method of claim 6 wherein the organic hydrocarbon component
includes an alkane.
8. A method of claim 5 wherein the hydrocarbon component includes
an aryl compound.
9. A method of claim 5 wherein the operating conditions of the
molten metal bath include establishing and maintaining a
temperature in a range of less than about 2,000.degree. C.
10. A method of claim 9 wherein the hydrocarbon-containing feed is
directed into the molten metal bath as a component of a fluid
stream that includes an inert gas component.
11. A method of claim 9 wherein the concentration of the
hydrocarbon-containing feed in the fluid stream is in the range of
between about five and forty percent, by volume.
12. A method of claim 11 wherein the hydrocarbon is a component of
oil.
13. A method of claim 11 wherein the hydrocarbon component of the
feed includes polyethylene.
14. A method of claim 5 wherein a bath of molten brass is
provided.
15. A method of claim 5 wherein a bath of molten aluminum is
provided.
16. A method of claim 1 where the hydrocarbon-containing feed
contains heteroatoms.
17. A method of claim 16 where the heteroatoms include sulfur,
nitrogen, oxygen, and chlorine.
.Iadd.18. An apparatus suitable for closed and sealed molten
metal-based reactions comprising: (a) an upper portion, wherein the
upper portion is characterized by an off-gas outlet; (b) a lower
portion wherein the lower portion is characterized by one or more
inlets having one or more lances disposed therein operably
connected to an inert gas source; (c) one or more feed inlets for
the introduction of feed streams; (d) an induction coil disposed
within the lower portion; (e) a means for controlling (1) the rate
of introduction of each feed stream, (2) the rate of removal of the
off gas, (3) the relative amounts of reaction components, (4) the
temperature of the molten metal; and/or (5) the carbon saturation
levels of the molten metal bath within residence times of between
0.1 and 5 seconds. .Iaddend.
.Iadd.19. The apparatus of claim 18 comprising one or more feed
inlets adapted for the introduction of a carbon-containing
material. .Iaddend.
Description
BACKGROUND OF THE INVENTION
Considerable research has been conducted recently in the area of
producing olefins for use as industrial raw materials. Among the
many uses of such commodity chemicals include plastic and fibers
for consumption in packaging, transportation and construction
industries. Of particular interest are areas of research focusing
on production of olefins, such as ethylene, which is consumed
principally in the manufacture of polyethylene, and substituted
alkenes, such as ethylene dichloride and vinyl chloride. Ethylene
is also employed in the production of ethylene oxide, ethyl
benzene, ethylene dichloride, ethylene-propylene elastomers and
vinyl acetate.
The primary sources of olefins, such as ethylene include: steam
cracking of organics, such as gas oils; off-gas from fluid
catalytic cracking (FCC) in oil refineries, catalytic dehydration
of alcohols; and recovery from coal-derived synthesis gas. However,
the worldwide demand for olefins is extraordinary: the short fall
in worldwide supply of ethylene alone was estimated in 1991 to be
about 2.3 million tons, as determined by the Chemical Economics
Handbook, SRI International (1992). Further, known methods for
producing olefins have significant drawbacks. For example, organic
steam-cracking, which accounts for about 100% of ethylene
production in the United States, is a mature technology which is
highly sensitive to process variables, such as cracking severity,
residence time and hydrocarbon partial pressure, as well as plant
economics and price fluctuation. In addition, such processes are
facing increasing environmental regulatory pressure to control
systemic problems, such as leaks and failure from related equipment
and safety concerns associated with olefin cracking.
Other listed production methods have even greater limitations. The
availability of FCC off-gas, for example, generally prohibits its
use as an economically viable feed stock. Catalytic dehydration of
alcohols is effectively limited to certain countries that have
large amounts of readily available fermentation raw material. Also,
known methods for production of olefins from other sources, such as
coal and coal-derived naphtha and methanol are, at best, only
marginally commercially viable.
Therefore, a need exists for an improved method of producing
olefins which significantly reduces or eliminates the
above-mentioned problems.
SUMMARY OF THE INVENTION
The invention relates to a method for reforming organics into
shorter-chain unsaturated organic compounds.
A molten metal bath is provided which can cause homolytic cleavage
of an organic component of an organic-containing feed. The feed is
directed into the molten metal bath at a rate which causes partial
homolytic cleavage of the organic component of the feed. Conditions
are established and maintained in the reactor to cause partial
homolytic cleavage of the organic component to produce
shorter-chain unsaturated organic compounds, which are discharged
from the molten metal bath.
The present invention has many advantages. For example, the present
invention provides good control over production of organics, such
as alkenes, including ethylene. Also, high yields of ethylene are
obtained by the present invention. The present method is a
recycling process, employing solution equilibria to synthesize
commercial products, such as methane, ethane and propane, from a
wide variety of organic feeds, including most hazardous industrial
wastes. The present invention also has the ability to sustain high
product quality, irrespective of feed heterogeneity, including
chemical or physical complexity. In addition, the invention
provides flexibility to engineer the properties and composition of
a ceramic phase generated by the method. Further, the present
invention has the ability to recover and recycle volatile and
nonvolatile materials.
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE is a schematic representation of one embodiment of
apparatus suitable for conducting the method of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The features and other details of the method of the invention will
now be more particularly described with reference to the
accompanying figures and pointed out in the claims. It will be
understood that particular embodiments of the invention are shown
by way of illustration and not as limitations of the invention. The
principal functions of this invention can be employed in various
embodiments without departing from the scope of the invention.
The present invention generally relates to a method reforming
organic components of a feed into shorter-chain unsaturated organic
compounds. An example of a suitable feed includes an organic waste.
Processes for decomposing waste in molten metal baths are disclosed
in U.S. Pat. Nos. 4,574,714, 5,177,304, and 4,602,574 which are
incorporated herein by reference.
In one embodiment of the invention, illustrated in FIG. 1, system
10 includes reactor 12. Examples of suitable vessels include those
described in U.S. Ser. No. 08/041,490 and U.S. Ser. No. 08/041,405,
the teachings of which are incorporated herein by reference, and
reactors which are described in U.S. Pat. Nos. 4,574,714,
5,177,304, and 4,602,574. Reactor 12 has an upper portion 14 and a
lower portion 16. Feed inlet 18 at upper portion 14 of reactor 12
is suitable for directing feed into reactor 12. Off-gas outlet 22
extends from upper portion 14 and is suitable for conducting an
off-gas out of reactor 12.
It is to be understood that the feed stream is generally introduced
to molten metal bath 44 without injection of a coolant if reaction
of the feed in reaction 12 is endothermic. However, tuyere 28 is
dimensioned and configured for conjointly and continuously
introducing a suitable feed stream and coolant into reactor 12.
Tuyere 28 includes coolant tube 30 and feed inlet tube 35. Coolant
tube 30 extends from coolant source 34 to reactor 12. Feed inlet
tube 35 extends from feed source 37 to tuyere 28. Feed inlet tube
35 is disposed at tuyere opening 32. Pump 39 is disposed at tuyere
28 to direct a suitable feed stream from feed source 37 and through
tuyere opening 32 into reactor 12.
It is to be understood that an oxidant can also be fed to reactor
12 through tuyere 28 and/or at other locations within reactor 12,
as are taught in U.S. Pat. No. 5,191,154, the teachings of which
are incorporated by reference. It is also to be understood that
more than one tuyere 28 can be disposed in reactor 12 and that
concentric, or multiple concentric tuyeres, can be employed for
separate introduction of the feed stream into reactor 12. Further,
it is to be understood that feed can be introduced into reactor 12
by other suitable methods, such as by employing a lance, etc.
Bottom-tapping spout 36 extends from lower portion 16 and is
suitable for removal of at least a portion of a molten bath from
reactor 12. Additional drains can be provided as a means of
continuously or intermittently removing distinct molten phases.
Material can also be removed by other methods, such as are known in
the art. For example, material can be removed from reactor 12 by
rotating vessel 12 and employing a launder, not shown, extending
from feed inlet 18. Alternatively, the launder can extend into
reactor 12 through a tap hole, also not shown.
Induction coil 38 is disposed at lower portion 16 for heating
reactor 12 or for initiating generation of heat within reactor 12.
It is to be understood that, alternatively, reactor 12 can be
heated by other suitable means, such as by plasma torch, electric
arc, etc. Trunions 40 are disposed at reactor 12 for manipulation
of reactor 12. Seal 42 is disposed between reactor 12 and off-gas
outlet 22 and is suitable for allowing partial rotation of reactor
12 about trunions 40 without breaking seal 42. Alternatively,
reactor 12 does not include trunions 40 or seal 42 and does not
rotate.
Molten metal bath 44 is disposed within reactor 12. In one
embodiment, molten metal bath 44 includes a metal which, when
molten, causes at least a portion of saturated hydrocarbon in the
injected feed to be reformed to at least one unsaturated alkene,
such as ethylene, under the operating conditions of system 10. In
one embodiment, the metals of molten metal bath 44 have a melting
point in the range of between about 900.degree. C. and
1,100.degree. C. The melting point of bath 44 is low enough to
cause the organic components of the injected feed to be reformed by
homolytic cleavage and to be subsequently discharged from bath 44
as at least one unsaturated organic compound.
In a particularly preferred embodiment, the operating conditions of
the bath include, for example, temperatures which prevent
substantial degradation of organic compounds. Also, the required
residence times of the feed in the bath of molten metal are
substantially shorter than are those typically employed to
thermally decompose organic-containing feeds.
Preferably, the carbon concentration in bath 44 is at a relatively
low level, such as a concentration which is substantially below the
saturation limit for the bath at the operating conditions of
reactor 12. The amount of carbon in molten metal bath 44 can be
controlled, for example: by the rate of introduction of the feed
stream, to molten metal bath 44; by controlling the rate of removal
of off-gas from molten metal bath 44; by controlling system
conditions, e.g., temperature, of system 10; by controlling the
relative amounts of other components in molten metal bath 44; etc.
For example, the organic-containing feed can be directed into
molten metal bath 44 at a rate which causes the residence time of a
carbon component of the feed to be greater than that required to
cause molten metal bath 44 to dissolve the carbon under the
operating conditions established and maintained in the reaction
zone.
The thermal history of the organic compounds in the reaction zone
is affected by the reaction zone temperature, residence time of the
compounds in the reaction zone, and various intensive properties
associated with materials in the reaction zone. The effective
operating temperature is that temperature to which organic species
of interest are exposed while they are in the reaction zone. This
temperature is chosen so as to maximize the conditions which lead
to product formation while minimizing any subsequent product
degradation reactions. The effective temperature can be achieved
under conditions supporting thermal equilibrium (e.g., having low
temperatures in the reaction zone and relatively long residence
times) or under conditions that prevent thermal equilibrium (e.g.,
very high temperatures in the reaction zone with relatively short
residence times). For example, if the optimal product formation
occurs at a substrate temperature of 900.degree. C., this could be
achieved with a liquid metal operating at 900.degree. C. and
allowing sufficient residence time for the product to reach thermal
equilibrium or it could be achieved by injecting it into a high
temperature reaction zone (e.g., 2000.degree. C.) for a very short
period of time thereby providing insufficient time for the product
to reach thermal equilibrium (i.e., allowing the product to exit
the reaction zone at 900.degree. C.). "Homolytic cleavage," as
defined herein, means cleavage of at least one carbon-carbon bond
of the organic component of the feed directed into reactor 12 to
form, for example, an organic compound having fewer carbon atoms.
"Partial homolytic cleavage," as defined herein means that the
homolytic cleavage product includes at least one organic
compound.
Examples of suitable metals in molten metal bath 44 include
transition metals and, in particular, transition metals which have
carbon solubility. Examples of especially suitable transition
metals include iron, chrome, vanadium, copper, aluminum, etc. It is
to be understood that molten metal bath 44 can include oxides of
the molten metals. As disclosed in U.S. Pat. No. 5,177,304, the
teachings of which are incorporated herein, molten metal bath 44
can include more than one phase of molten metal. In one embodiment,
molten metal bath 44 is formed of a ceramic phase which includes at
least one metal oxide. In another embodiment, the ceramic phase can
include at least one salt. Alternatively, a substantial portion of
molten metal bath 44 can be of elemental metal.
Molten metal bath 44 can be formed by at least partially filling
reactor 12 with a suitable metal. The metal is then heated to a
suitable temperature by activating induction coil 38 or by other
means, not shown. Optionally, two immiscible metals can be
introduced to reactor 12, whereby the metals separate during
melting to form two distinct molten metal phases. In one
embodiment, the viscosity of at least one phase of molten metal
bath 44 is less than about ten centipoise at the operating
conditions of system 10. In another embodiment, the viscosity of at
least one phase of molten metal bath 44 is less than about thirty
poise at the operating conditions of system 10.
Suitable operating conditions of system 10 include a temperature
sufficient to chemically react feed from feed source 37 and thereby
form at least one metallic carbide. "Metallic carbide," as that
term is used herein, means a compound or complex which is a product
of a reaction or some other interaction between a metal and a
component of a feed stream directed into molten metal bath 44.
Ceramic layer 50 is disposed on molten metal bath 44. Ceramic layer
50 is substantially immiscible with molten metal bath 44.
Alternatively, system 10 does not include ceramic layer 50. The
solubility of carbon in ceramic layer 50 can be less than that of
molten metal bath 44, thereby causing atomic carbon to be retained
within molten metal bath 44. In another embodiment, ceramic layer
50 has a lower thermal conductivity than that of molten metal bath
44. Radiant loss of heat from molten metal bath 44 can thereby be
reduced to significantly below the radiant heat loss from molten
metal bath 44 when no ceramic layer 50 is present.
Examples of suitable metal oxides of ceramic layer 50 include
titanium oxide (TiO.sub.2), zirconium oxide (ZrO.sub.2), aluminum
oxide (Al.sub.2O.sub.3), magnesium oxide (MgO), calcium oxide
(CaO), silica (SiO.sub.2), etc. Other examples of suitable
components of ceramic layer 50 include halogens, sulfur,
phosphorus, heavy metals, etc. It is to be understood that ceramic
layer 50 can include more than one metal oxide. Ceramic layer 50
can contain more than one phase. Typically, ceramic layer 50 is
substantially fluid and free radicals and other gases can pass
across ceramic layer 50 from molten metal bath 44.
Ceramic layer 50 can be formed by directing suitable materials,
such as metals, metal oxides, halogens, sulfur, phosphorus, heavy
metals, sludges, etc., from source 52 through inlet tube 54 and
into molten metal bath 44. The materials from source 52 can be
directed onto the top of molten metal bath 44 or injected into
molten metal bath 44, using methods such as are well-known in the
art. The materials can form other stable compounds at the operating
conditions of system 10 by reaction, for example, with alkali metal
cations or alkaline earth metal cations. Examples of such stable
reaction products include calcium fluoride (CaF.sub.2) and
magnesium phosphate (Mg(PO.sub.4).sub.2). In one embodiment,
ceramic layer 50 contains about forty percent calcium oxide, about
forty percent silicon dioxide, and about twenty percent aluminum
oxide, and is about five inches thick.
Feed, such as an organic-containing waste in solid, liquid, or
gaseous form, is directed from feed source 37 into a reaction zone
within reactor 12. The reaction zone is defined to be the region in
which the product formation reaction(s) occur. It can include the
volume within the reactor and within attached off-gas handling
equipment. The conditions supporting reaction includes liquid metal
system, the gas/liquid interface, and the gas above the liquid
metal which contains metal vapor and reactive metal particles and
droplets (such as can be formed by entrainment).
The feed can be introduced to reactor through line 35, line 51
and/or line 53. The feed includes at least one organic component.
Examples of suitable organic components include methane, ethane,
and propane. Examples of suitable alkyl hydrocarbons include
n-hexane and polyethylene. Examples of suitable feeds include
"dirty" crude oil, bottoms from oil refineries, oil shales,
hazardous wastes, etc.
In one embodiment, the feed is injected into molten metal bath 44
as a component of a feed stream that also includes an inert gas
component, such as argon. In one example, the feed stream is formed
by vaporizing liquid organic feed in the presence of an inert gas.
The amount of volatilized feed component in the feed stream can be,
for example, in the range of between about five and forty percent.
In addition to hydrogen and carbon, the organic component of the
feed stream can also include other atomic constituents, such as
halides, metals, etc.
The feed stream directed into reactor 12 combines with molten metal
bath 44 and can also combine with ceramic layer 50. The feed stream
and coolant are directed into molten metal bath 44 through tuyere
28. The feed stream can also be directed into reactor 16 from feed
source 37 through conduit 51. Conduit 51 discharges the feed
beneath the surface of molten metal bath 44. Contact of the feed
with molten metal bath 44 or ceramic layer 50 exposes the feed to
conditions sufficient to form an unsaturated organic product.
Consistent with the reaction zone definition, the reaction can be
carried out predominantly in the liquid metal phase, the space
immediately above the condensed liquid metal phase, or in the gas
space above the condensed reaction media bath provided that
sufficient concentrations of vapor, droplets, particles, etc.,
exist to support the necessary reaction rates. Optionally, at least
a portion of molten metal bath 44 can be suspended by gas directed
through tuyere 28. Suspended molten metal bath 44 can be a
continuum of metal extending through a generally gaseous volume or
a region of particulate molten metal suspended in a generally
gaseous volume within reactor 12.
At least one metal component of the bath of molten metal causes the
saturated hydrocarbon feed to dissociate to form unsaturated
alkenes through a metallic carbide. The metal carbide is formed
under the operating conditions of the bath of molten metal which
are established and maintained according to the method of the
invention. The operating conditions can include, for example, low
effective bath temperature, carbon solubility of the bath, and
short contact and residence times of the organic component in the
bath. Examples of particular embodiments of suitable operating
conditions include: a bath temperature in the range of between
900.degree. C. and 1,100.degree. C.; solubilities for carbon
exhibited by aluminum, copper and brass at that temperature; and
residence times of the organic component sufficient to achieve
thermal equilibrium in the bath of molten metal in the range of
between 0.1 and 5 seconds, or less than 0.1 seconds if thermal
equilibrium is not achieved. "Thermal equilibrium," as defined
herein, means that the temperature within the reaction zone is
substantially uniform.
If necessary, a coolant can be employed to cool tuyere 28. Examples
of suitable coolants include steam, methane (CH.sub.4), hydrogen
gas (H.sub.2), etc.
Gaseous layer 56 is formed over ceramic layer 50. In one
embodiment, gaseous layer 56 extends from upper portion 14 of
reactor 12 through off-gas outlet 22 to scrubber 82. A reaction
zone within system 10 includes molten metal bath 44, ceramic layer
50 and gaseous layer 56. Reactants, can be introduced anywhere
within the reaction zone. Gaseous layer 56 includes off-gas formed
in molten metal bath 44 and in ceramic layer 50. The off-gas
includes reaction products, such as unsaturated organic compounds
formed in molten metal bath 44. The off-gas can also include at
least one intermediate component which has been entrained or which
has been volatilized before reformation to a shorter-chain
unsaturated alkene is complete.
off-gas formed in reactor 12 is conducted from the reaction zone
through off-gas outlet 22 to heat exchanger 64. Heat exchanger 64
can be any suitable heat exchanger for cooling off-gas discharged
from reactor 12. Examples of suitable heat exchangers include
water-cooled hoods, shell-and-tube heat exchangers, fluid beds,
etc. Examples of off-gas components include unreacted or fragmented
portions of the organic-containing component.
The off-gas is conducted into heat exchanger 64 through heat
exchanger off-gas inlet 66 and then through heat-exchanger off-gas
outlet 68. Optionally, the off-gas is cooled in heat exchanger 64
by conducting the off-gas through an off-gas side 70 of heat
exchanger 64 and by directing a suitable cooling medium through a
medium-side 72 of heat exchanger 64. Examples of suitable cooling
mediums include, for example, water, ethylene glycol, ethyl
benzene, alcohols, etc. The cooling medium is directed from cooling
medium source 74 through cooling medium inlet 76 of heat exchanger
64 by a suitable means, such as by use of pump 78 disposed between
cooling medium source 74 and heat exchanger 64. The cooling medium
is directed through the medium side 72 of heat exchanger 64,
thereby cooling the off-gas, and then directed out of heat
exchanger 64 through cooling medium outlet 80.
The off-gas is directed out of heat exchanger off-gas outlet 68 to
a suitable separating means for exposing the off-gas to conditions
sufficient to remove at least a portion of an intermediate
component from the off-gas. In one illustration, the separating
means is scrubber 82. The off-gas is directed through scrubber
off-gas inlet 84 and then through scrubber 82 to scrubber off-gas
outlet 86.
Scrubber fluid 88 is directed from scrubber fluid source 90 to
scrubber 82 by a suitable means, such as by gravity or by a pump,
not shown. Scrubber fluid 88 is introduced to scrubber 82 at a
temperature suitable for removing at least a portion of the
component from the off-gas.
It is to be understood that additional separating means can be
employed to separate components from off-gas discharged from
reactor 16. For example, a suitable cyclone separator, not shown,
and a suitable spray drier, also not shown, can be disposed between
heat exchanger 64 and scrubber 82.
Liquid composition 92 is formed by scrubbing of the off-gas with
scrubber fluid 88. Liquid composition 92 is directed from scrubber
82 to reactor 12. In one embodiment, liquid composition 92 is
pumped through piping 94 by pump 96 to the feed inlet tube 35.
Examples of suitable pumps include a centrifugal pump, a positive
displacement pump, etc. Liquid composition 92 is thereby combined
with the feed for introduction into molten metal bath 44 through
tuyere 28. In another embodiment, liquid composition 92 is directed
through piping 97 by pump 99 to conduit 51. Liquid composition 92
is thereby combined with the feed stream for introduction into
reactor 12 and onto molten metal bath 44.
At least a portion of the off-gas components are thereby returned
in liquid composition 92 from the off-gas to molten metal bath 44.
A substantial portion of the discharged feed components are then
chemically reformed to shorter-chain unsaturated hydrocarbons, such
as ethylene. Chemical reaction of the feed components in system 10
is thereby controlled.
The invention will now be further and specifically described by the
following examples. All parts of percentages are by weight unless
otherwise stated.
EXAMPLE 1
A 20 lb. hot metal-capacity unit was used for the experimental
trials, with a susceptor/crucible arrangement used for containment
and heating. The off-gas was sealed to a gas-handling train for
analysis. In order to minimize the complexity associated with
solids handling, isomeric surrogates of polyethylene were used. The
injection was achieved by bubbling inert gas through the liquid
hexane to yield an inlet concentration given by the vapor pressure
of hexane. The gas mixture was subsequently bubbled into the molten
metal bath, with steady state being achieved after 15 minutes.
The results of these scoping experiments are summarized in Tables 1
and 2 below.
TABLE-US-00001 TABLE 1 Ethylene Metal Temperature Concentration
Selectivity Substrate .degree. C. Feed (%) (%) Brass 1050 n-hexane
18 2 Brass 900 n-hexane 18 35 Brass 900 n-hexane 31 30
TABLE-US-00002 TABLE 2 Ethylene Metal Temperature Concentration
Selectivity Substrate .degree. C. Feed (%) (%) Aluminum 900
n-hexane 6 <0.5 Aluminum 900 n-hexane 13 22 Aluminum 900
2-methyl- 18 19 pentane
EXAMPLE 2
A 20 lb. hot metal-capacity unit was used for the experimental
trials, with a susceptor/crucible arrangement used for containment
and heating. Various organic liquids were fed and the production of
unsaturated organics was monitored. Feed addition was achieved by
vaporizing the organic and sweeping it with an inert gas to achieve
the desired inlet concentration. The gas mixture was subsequently
added into the molten metal bath with steady state being achieved
after 15 minutes. The results are summarized below.
TABLE-US-00003 TABLE 3 Ethylene Metal Temperature Concentration
Selectivity Substrate .degree. C. Feed (%) (%) Copper 900 n-hexane
18 35 Aluminum 900 n-hexane 13 22 Aluminum 900 2-methyl- 18 19
pentane
Equivalents
Those skilled in the art will recognize, or be able to ascertain
using no more than routine experimentation, many equivalents of the
invention described specifically herein. Such equivalents are
intended to be encompassed in the scope of the following
claims.
* * * * *