U.S. patent application number 10/893418 was filed with the patent office on 2005-02-17 for hydrocarbon synthesis.
Invention is credited to Lorkovic, Ivan M., Noy, Maria, Sherman, Jeffrey H., Stucky, Galen D., Weiss, Michael J..
Application Number | 20050038310 10/893418 |
Document ID | / |
Family ID | 34272464 |
Filed Date | 2005-02-17 |
United States Patent
Application |
20050038310 |
Kind Code |
A1 |
Lorkovic, Ivan M. ; et
al. |
February 17, 2005 |
Hydrocarbon synthesis
Abstract
A method of synthesizing hydrocarbons from smaller hydrocarbons
includes the steps of hydrocarbon halogenation, simultaneous
oligomerization and hydrogen halide neutralization, and product
recovery, with a metal-oxygen cataloreactant used to facilitate
carbon-carbon coupling. Treatment with air or oxygen liberates
halogen and regenerates the cataloreactant.
Inventors: |
Lorkovic, Ivan M.; (Santa
Barbara, CA) ; Noy, Maria; (Carpinteria, CA) ;
Sherman, Jeffrey H.; (Sebastian, FL) ; Weiss, Michael
J.; (Santa Barbara, CA) ; Stucky, Galen D.;
(Goleta, CA) |
Correspondence
Address: |
CHRISTIE, PARKER & HALE, LLP
PO BOX 7068
PASADENA
CA
91109-7068
US
|
Family ID: |
34272464 |
Appl. No.: |
10/893418 |
Filed: |
July 15, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60487364 |
Jul 15, 2003 |
|
|
|
Current U.S.
Class: |
585/310 ;
585/943 |
Current CPC
Class: |
C07C 2521/10 20130101;
Y10S 585/935 20130101; C07C 2529/40 20130101; C07C 1/26 20130101;
C07C 2523/02 20130101; Y10S 585/943 20130101; Y02P 20/52 20151101;
C07C 2529/18 20130101; C07C 17/10 20130101; C07C 17/10 20130101;
C07C 19/075 20130101; C07C 1/26 20130101; C07C 11/04 20130101; C07C
1/26 20130101; C07C 11/06 20130101 |
Class at
Publication: |
585/943 ;
585/324; 585/310 |
International
Class: |
C07C 002/00 |
Claims
What is claimed is:
1. A method of making a hydrocarbon having a carbon number C.sub.n,
where n.gtoreq.2, comprising: forming a halogenated hydrocarbon by
allowing a reactant hydrocarbon having a carbon number C.sub.m,
where m<n, to react with a halogenating agent; forming a product
hydrocarbon having a carbon number C.sub.n, where n.gtoreq.2, by
allowing the halogenated hydrocarbon to contact a metal-oxygen
cataloreactant; recovering the product hydrocarbon; and
regenerating the cataloreactant.
2. A method as recited in claim 1, wherein the reactant hydrocarbon
comprises methane.
3. A method as recited in claim 1, wherein the metal-oxygen
cataloreactant is selected from the group consisting of zeolites,
doped zeolites, metal oxides, mixed metal oxides, metal
oxide-impregnated zeolites, and mixtures thereof.
4. A method as recited in claim 1, wherein the cataloreactant is
regenerated with air or oxygen.
5. A method as recited in claim 1, wherein synthesis of the product
hydrocarbon is carried out in a zone reactor.
6. A method as recited in claim 1, wherein the halogenating agent
comprises molecular halogen.
7. A method as recited in claim 1, wherein the molecular halogen
comprises bromine.
8. A method as recited in claim 1, wherein the halogenating agent
comprises an alkyl halide.
9. A method as recited in claim 1, wherein the halogenating agent
comprises a solid halide.
10. A method as recited in claim 1, wherein the halogenating agent
comprises a hydrogen halide.
11. A method of making a hydrocarbon having a carbon number
C.sub.n, where n.gtoreq.2, comprising: forming a brominated
hydrocarbon by allowing a reactant hydrocarbon having a carbon
number C.sub.m, where m<n, to react with a brominating agent;
forming a product hydrocarbon having a carbon number C.sub.n, where
n.gtoreq.2, by allowing the brominated hydrocarbon to contact a
metal-oxygen cataloreactant; recovering the product hydrocarbon;
and regenerating the cataloreactant.
12. A method as recited in claim 11, wherein the reactant
hydrocarbon comprises methane.
13. A method as recited in claim 11, wherein the metal-oxygen
cataloreactant is selected from the group consisting of zeolites,
doped zeolites, metal oxides, mixed metal oxides, metal
oxide-impregnated zeolites, and mixtures thereof.
14. A method as recited in claim 1, wherein the cataloreactant is
regenerated with air or oxygen.
15. A method as recited in claim 1, wherein synthesis of the
product hydrocarbon is carried out in a zone reactor.
16. A method as recited in claim 1, wherein the halogenating agent
is selected from the group consisting of bromine, alkyl bromides,
solid bromides, and hydrogen bromide.
17. A method of making a hydrocarbon having a carbon number
C.sub.n, where n.gtoreq.2, comprising: (i) forming an alkyl halide
by allowing a reactant alkane having a carbon number C.sub.m, where
m<n, to react with molecular halogen; (ii) forming a product
hydrocarbon having a carbon number C.sub.n, where n.gtoreq.2, by
allowing the alkyl halide to contact a metal-oxygen cataloreactant;
(iii) recovering the product hydrocarbon; and (iv) regenerating the
cataloreactant with air or oxygen.
18. A method as recited in claim 17, wherein the reactant
hydrocarbon comprises methane.
19. A method as recited in claim 17, wherein the molecular halogen
comprises bromine.
20. A method as recited in claim 17, wherein step (i) occurs at an
alkane-to-halogen ratio of from 1:10 to 1:100 by volume.
21. A method as recited in claim 19, wherein step (i) occurs at a
temperature of from 20 to 900.degree. C. and a pressure of from 0.1
to 200 atm.
22. A method as recited in claim 17, wherein the metal-oxygen
cataloreactant is selected from the group consisting of zeolites,
doped zeolites, metal oxides, mixed metal oxides, metal
oxide-impregnated zeolites, and mixtures thereof.
23. A method as recited in claim 17, wherein the cataloreactant is
regenerated with air or oxygen.
24. A method as recited in claim 17, wherein steps (i)-(iv) take
place in a zone reactor.
25. A method of making a hydrocarbon having a carbon number
C.sub.n, where n.gtoreq.2, comprising: (i) forming an alkyl halide
by allowing methane to react with molecular bromine, at a
temperature of from 20 to 900.degree. C., a pressure of from 0.1 to
200 atm, and a methane-to-bromine ratio of from 1:10 to 1:100 by
volume; (ii) forming a product hydrocarbon having a carbon number
C.sub.n, where n.gtoreq.2, by allowing the alkyl bromide to contact
a doped zeolite; (iii) recovering the product hydrocarbon; and (iv)
regenerating the doped zeolite with air or oxygen; wherein steps
(i)-(iv) occur in a zone reactor.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 60/487,364, filed Jul. 15, 2003.
FIELD OF THE INVENTION
[0002] This invention relates generally to hydrocarbon
oligomerization, and more particularly to a method of making
hydrocarbons using cataloreactants.
BACKGROUND OF THE INVENTION
[0003] Scientists have long sought efficient ways to convert
methane and other alkanes into higher hydrocarbons, including light
olefins and gasoline-range materials. Efficient processes could
create value in a number of ways, including: facilitating the
utilization of remotely located stranded natural gas through its
conversion into more easily transportable liquid fuels and
feedstocks, and allowing the use of inexpensive feedstocks (methane
and other lower alkanes) for end products often made from higher
alkanes, including ethylene and propylene.
[0004] U.S. Pat. Nos. 6,486,368, 6,472,572, 6,465,699, 6,465,696,
and 6,462,243 disclose processes for converting alkanes into
olefins, ethers, and alcohols. Many of the disclosed processes
involve halogenation of an alkane, passing the halogenated products
over a metal oxide to create products and metal halide, recovering
the product(s), and regenerating the metal halide with oxygen or
air to yield metal oxide and halogen for recycle to the process.
Not described is alkane oligomerization: substantial coupling of
the starting hydrocarbon to obtain product(s) of higher carbon
number.
[0005] Several investigators have examined the use of halogenation
for the production of higher hydrocarbons from methane.
Representative patents include U.S. Pat. Nos. 4,513,092 (Chu),
4,769,504 (Noceti and Taylor), 5,087,786 (Nubel), and 6,452,058
(Schweitzer). As described in the Taylor patent: "Aromatic-rich,
gasoline boiling range hydrocarbons [are made] from the lower
alkanes, particularly from methane. The process is carried out in
two stages. In the first, alkane is reacted with oxygen and
hydrogen chloride over an oxyhydrochlorination catalyst such as
copper chloride with minor proportions of potassium chloride and
rare earth chloride. This produces an intermediate gaseous mixture
containing water and chlorinated alkanes. The chlorinated alkanes
are contacted with a crystalline aluminosilicate catalyst in the
hydrogen or metal-promoted form to produce gasoline range
hydrocarbons with a high proportion of aromatics and a small
percentage of light hydrocarbons (C.sub.2-C.sub.4), as well as
reforming the HCl. The light hydrocarbons can be recycled for
further processing over the oxyhydrochlorination catalyst." All of
these techniques for making higher alkanes from C.sub.1 feedstocks
suffer from the disadvantage that the hydrocarbon stream must be
separated from an aqueous hydrohalic acid stream, and the
hydrohalic acid stream must be recycled.
[0006] U.S. Pat. No. 4,795,843 (Tomotsu et al.) discloses a process
for oligomerizing halomethanes to products including ethyl benzene,
toluene, and xylenes, using silica polymorph or silicalite
catalysts. The process does not incorporate reactive neutralization
of hydrogen halide, and appears to suffer from slow kinetics.
[0007] In a process for halogenating hydrocarbons, Chang and
Perkins noted trace amounts of oligomerization products in the
presence of zeolites in U.S. Pat. No. 4,654,449. The
oligomerization products were low in quantity, and generally
halogenated.
[0008] U.S. Pat. No. 4,373,109 (Olah) discloses a process for
converting heterosubstituted methanes, including methyl halides, by
contacting such methanes with bifunctional acid-base catalysts at
elevated temperatures, between 200 and 450.degree. C., preferably
between 250 and 375.degree. C., to produce predominantly lower
olefins, preferably ethylene and propylene. The catalysts of
preference are those derived from halides, oxyhalides, oxides,
sulfides or oxysulfides of transition metals of Groups IV, V, VI,
VIII of the Periodic Table, such as tantalum, niobium, zirconium,
tungsten, titanium, and chromium, deposited on acidic oxides and
sulfides such as alumina, silica, zirconia or silica-alumina.
Neither the use of solid oxide-based halogen recovery nor the
formation of alcohols or ethers is disclosed. A related reference
is "Ylide chemistry. 1. Bifunctional acid-base-catalyzed conversion
of heterosubstituted methanes into ethylene and derived
hydrocarbons. The onium-ylide mechanism of the C1.fwdarw.C2
conversion" by George A. Olah et al. (J. Am. Chem. Soc. 106, 2143
(1984)).
[0009] U.S. Pat. No. 3,894,107 (Butter, et al.) discloses
improvements to a process for condensing halogenated hydrocarbons
using zeolite catalysts. Notably absent is any discussion of solid
oxide-based hydrogen halide neutralization.
[0010] Kochi has observed reductive coupling of alkyl halides when
transition metal bromides are reacted with low-molecular weight
Grignard reagents in THF or diethyl ether (Bulletin of the Chemical
Society of Japan v. 44 1971 pp. 3063-73). Liquid phase chemistry,
however, typically suffers from such disadvantages as the
requirement of solvent, corrosion, and lower rates of reaction than
gas-phase chemistry. In addition, such a process consumes energy
required to produce the magnesium metal needed for the energetic
and reducing Grignard reagents. This is not the same type of
process as the dehydrohalogenative coupling and hydrogen halide
neutralization we describe herein.
SUMMARY OF THE INVENTION
[0011] The present invention addresses the need for an efficient
way to convert methane and other hydrocarbons into higher
hydrocarbons. In one embodiment, a hydrocarbon having a carbon
number C.sub.n, where n.gtoreq.2, is prepared by allowing a
reactant hydrocarbon having a carbon number C.sub.m, where m<n,
to react with a halogenating agent, thereby forming a halogenated
hydrocarbon; allowing the halogenated hydrocarbon to contact a
metal-oxygen cataloreactant, thereby forming a product hydrocarbon
having an carbon number C.sub.n, where n.gtoreq.2; recovering the
product hydrocarbon; and regenerating the cataloreactant. Often, a
mixture of hydrocarbons is obtained, but careful selection of the
reactant hydrocarbon, halogenating agent, metal-oxygen
cataloreactant, and reaction conditions allow a tailored approach
to hydrocarbon product formation. Methane (i.e., natural gas) as
well as other light hydrocarbons, e.g., C.sub.2 to C.sub.6
hydrocarbons, are envisioned as preferred feedstocks.
[0012] Although laboratory observations have thus far focused on
methane oligomerization with detection of ethylene, propylene,
butenes and aromatics, the invention contemplates the use of
feedstocks having carbon numbers as high as C.sub.10.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention exploits the discovery that
metal-oxygen compounds, such as mixed metal oxides, particularly
metal oxide-impregnated zeolites, facilitate hydrocarbon
oligomerization. According to one aspect of the invention, a
hydrocarbon having a carbon number C.sub.n, where n.gtoreq.2, is
formed by (i) forming a halogenated hydrocarbon by allowing a
reactant hydrocarbon having a carbon number C.sub.m, where m<n,
to react with a halogenating agent; (ii) forming a product
hydrocarbon having a carbon number C.sub.n, where n.gtoreq.2, by
allowing the halogenated hydrocarbon to contact a metal-oxygen
cataloreactant; (iii) recovering the product hydrocarbon; and (iv)
regenerating the cataloreactant.
[0014] More generally, the method entails the steps of
halogenation, oligomerization, product recovery, and cataloreactant
regeneration. The halogenated products may be separated from the
unreacted (non-halogenated) hydrocarbon either before or after
reaction with the metal-oxygen cataloreactant. Neutralization of
any hydrohalic acid formed during the synthesis is advantageously
accomplished concommitantly with carbon-carbon coupling and/or
cataloreactant regeneration. Preferably, the process is an
integrated one and takes place, for example, in a zone reactor, as
described, for example, in U.S. Pat. No. 6,525,230 (Grosso), the
entire contents of which is incorporated by reference herein. Thus,
halogenation of methane or other hydrocarbons occurs within one
zone of the reactor, and is followed by a condensation step in
which the liberated hydrohalic acid is adsorbed within the same
bifunctional material that catalyzes condensation of the
halogenated hydrocarbon. Hydrocarbon oligomerization (defined as
carbon-carbon coupling) takes place within this zone of the reactor
and yields product hydrocarbons which, in general, will have carbon
numbers ranging from C.sub.2 to C.sub.20, and may include alkanes,
alkenes, alkynes, and/or aromatics. Treatment with air or oxygen
liberates halogen for use in subsequent halogenation steps, and
regenerates the cataloreactant material for subsequent condensation
or metathesis. Advantageously, the need for recycling/recovering
corrosive, aqueous hydrohalic acid is avoided because regeneration
and recovery takes place in situ.
[0015] Higher hydrocarbon synthesis begins with a hydrocarbon
feedstock: one or more reactant hydrocarbons, each having,
independently, a carbon number C.sub.m, where m<n, C.sub.n being
the carbon number of the target hydrocarbon(s). Non-limiting
examples of reactant hydrocarbons include methane, ethane, propane,
etc., with natural gas (predominately methane, but often including
small amounts of C.sub.2 and higher species) being preferred. In
general, the starting hydrocarbon has a carbon number between 1 and
10. Mixtures of hydrocarbons may also be used.
[0016] The reactant hydrocarbons are allowed to react with a
halogenating agent. Non-limiting examples include molecular halogen
(e.g., bromine, chlorine, etc.), alkyl halides (e.g.,
dibromomethane, bromoform, carbon tetrabromide), and condensed
halides, such as metal bromides, which may be present as a solid,
liquid, supported, or unsupported material. Molecular halogens are
preferred, with bromine (Br.sub.2) being most preferred. Bromine is
a liquid at room temperature, less reactive than chlorine and
fluorine, and easy to handle. Bromine also has favorable
energetics.
[0017] The reduction potential of bromine to bromide is 1.07 V vs.
NHE, while that of oxygen to water is 1.23 V. A broad range of
metal bromides may release bromine upon treatment with oxygen. At
the same time, alkane bromination and subsequent alkyl bromide
coupling and HBr neutralization are only mildly exothermic, but
spontaneous enough to go to completion. Water and coupled
hydrocarbons are the only fluid products. The same is not true with
chlorine as mediator, for which HCl is a major component of the
product stream. Hydrogen chloride production requires separation,
drying, and recycling, which is costly. In short, the
thermochemistry of metal bromide-mediated alkane partial oxidiation
is well-suited for efficient and inexpensive plant operation.
[0018] Halogenation of the reactant hydrocarbon may proceed in a
number of ways, depending in part on the desired product(s) and in
part on the feed. In one embodiment, an alkane is halogenated with
molecular halogen using heat, light, or other electromagnetic
radiation to drive the reaction, with heat being preferred. There
is some benefit in having all steps--halogenation, oligomerization,
and regeneration (described below)--occur at roughly the same
temperature. As typical temperatures for methanol to olefin (MTO)
and methanol to gasoline (MTG) processes, temperatures of from 375
to 450.degree. C. are utilized, with the range being important, if
not critical. For the carbon-carbon coupling process described
herein, an ideal temperature range, where all steps occur at
roughly the same temperature, is 450 to 550.degree. C.
Alternatively, individual reaction steps might be carried out at
temperatures above or below this range.
[0019] Halogenation preferably occurs at a pressure between 0.1 and
200 atm, for the subsequent carbon-carbon step. Low pressure favors
less carbon-carbon coupling (i.e., a smaller average molecular
weight of product), while high pressure favors higher coupling.
Processes for light olefins are likely to run at the same 60 to 200
psia that methanol to olefin (MTO) processes are run at, although
higher pressures may alternatively be utilized. For production of
gasoline-range molecules, pressures around 350 psia, as used in
methanol to gasoline (MTG) processes, are envisioned. As a
practical matter, running below atmospheric (more conservatively,
below 2 psia) or above 100 atm is unlikely.
[0020] When molecular halogen is used as the halogenating agent,
halogenation ideally is carried out at an alkane:halogen ratio of
between 1:10 and about 100:1, on a volume by volume basis. At
alkane:halogen ratios of less than 1:10 (i.e., more halogen),
multi-halogenated hydrocarbons will be formed, typically leading to
complete oxidation (i.e., CO.sub.2) upon subsequent contact with
the metal-oxygen cataloreactant. At alkane:halogen ratios higher
than 100:1, the conversion to a halogenated hydrocarbon will be too
low, perhaps 1% or less, and it is nearly impossible to imagine an
economical process at such conversion levels. (30-60% conversion
are more likely lower limits).
[0021] Altering the ratio of halogen to alkane or other hydrocarbon
feedstock may have a marked impact on product distribution. For
example, one may choose to control the degree of halogenation in
order to reduce aromatic formation in the production of lower
olefins or fuels. A second example is minimizing formation of
highly halogenated methane in order to reduce the formation of
alkynes.
[0022] A key feature of the invention is the use of a metal-oxygen
cataloreactant, which facilitates carbon-carbon coupling, i.e.,
hydrocarbon oligomerization. The term "metal-oxygen cataloreactant"
is used herein to refer to a cataloreactant material containing
both metal and oxygen. While not bound by theory, it is believed
that the material catalyzes carbon-carbon coupling via hydrogen
halide (e.g., HBr) elimination and alkylidene insertion into
cationically activated C--H and possibly C--C bonds. The
cataloreactant also acts as a halogen release and sequestering
agent, and offers the possibility of obtaining a tunable coupling
product distribution, including the ability to produce oxygenates
if desired, while simultaneously trapping and recovering halogen,
emitting only water as a byproduct. Treatment with air or oxygen
regenerates the cataloreactant.
[0023] Nonlimiting examples of metal-oxygen cataloreactants include
zeolites, doped zeolites, metal oxides, mixed metal oxides, metal
oxide-impregnated zeolites, and similar materials, as well as
mixtures of such materials. Nonlimiting examples of dopants include
calcium and magnesium, and their oxides and/or hydroxides.
[0024] Zeolites are available from a variety of sources, including
Zeolyst International (Valley Forge, Pa.). Specific examples
include doped-ZSM-5 and doped mordenite (where, e.g., calcium
and/or magnesium are the dopants).
[0025] Shifting the properties of the zeolite or zeolite component
of a zeolite/metal oxide composite is also expected to shift
product distribution. Pore size and acidity are particularly
expected to be important. Acidity may be used to control chain
length and functionality, and pore size may control chain length
and functionality. Zeolites of particular pore-size may selectively
produce benzene, toluene, para-xylene, ortho-xylene, meta-xylene,
mixed xylenes, ethyl benzene, styrene, linear alkyl benzene, or
other aromatic products. The use of pore size is not limited to
aromatic products.
[0026] In one embodiment of the invention, a metal oxide/zeolite
composite is prepared by mixing a zeolite with a metal nitrate
(e.g., calcium nitrate) or hydrated species thereof.
[0027] After oligomerization, the metal-oxygen cataloreactant is
regenerated by treatment with air or oxygen, typically at a
temperature of from 200 to 900.degree. C. This converts metal
halide species into metal-oxygen species.
[0028] A number of variables, including feed composition, feed
location in the reactor, temperature, pressure, metal oxide
composition, and reactor residence time may alter the product
distribution. Production of alkanes, olefins and aromatics from
methane has been detected and confirmed. Also expected is the
ability to produce alkanes and olefins of particular branching
(including mono-methyl branched alcohols), alcohols, diols, ethers,
halogenated hydrocarbons, aromatics including benzene, styrene,
ethyl benzene, toluene, xylenes, and linear alkyl benzenes, and
hydrocarbons suitable for fuels such as gasoline, diesel, and jet
fuel.
[0029] Control of the feed composition can control the product
distribution. First, hydrogen halide produced in the halogenation
may be neutralized (to form water or alcohol) with the same
metal-oxygen compound producing the hydrocarbon product(s), or with
a separate metal-oxygen compound in a distinct reactor. Shifting
the hydrogen halide neutralization location may shift the product
distribution, including functionality, chain length, and branching.
For example, concurrent neutralization and product formation may be
expected to drive the production of alcohols, which may or may not
undergo further reactions such as coupling or dehydration. Second,
water addition to the feed may shift product distribution. In
particular, the addition of water may favor alcohol products. The
addition of water may also control degree and type of branching and
chain length. Third, hydrogen addition may alter the product
distribution. Hydrogen may increase alkanes at the expense of other
functionalities, something particularly useful for producing fuels.
Hydrogen may also reduce coking and help control the chain length
and branching.
[0030] It will also be appreciated that carbon-carbon
oligomerization may proceed by a number of pathways. Even
single-hydrocarbon feedstocks may yield more than one product. On
the other hand, in one embodiment of the invention, controlled
halogentation is used to produce predominately one isomer in favor
of another (e.g., selective formation of 1-butene or 2-butene).
Mixed feedstocks, such as raw natural gas, may give rise to
oligomerization of multiple halogenated hydrocarbons (e.g., ethyl
halide, dihaloethane, methyl halide, methyl dihalide, propyl
halide, propyl dihalide, etc.). Indeed, in one embodiment of the
invention, an alkyl halide is purposefully introduced to create
desired branched products. An example would be oligomerization of
methyl halide (from methane) with ethyl halide or a higher alkyl
halide to produce, selectively, methyl, ethyl, propyl, isopropyl,
or tertiary butyl (or other) branching. Another example might be
the synthesis of styrene from ethyl halide, methyl halide, and
dihalomethane.
[0031] In one embodiment of the invention, the reaction of
halogenated hydrocarbon with a metal-oxygen cataloreactant takes
place in a fluidized bed. Alternatively, a fixed bed is employed.
Different alkyl halides may be introduced at different locations in
the reactor. One example is the introduction of methyl halides at
one location in a reactor to produce benzene, to which ethyl
halides are added, producing styrene or ethyl benzene. Another
example is the introduction of methyl halides at one location in a
reactor to produce benzene, to which alkyl halides are added,
producing linear alkyl benzene.
[0032] Product separation is accomplished by any suitable method.
Nonlimiting examples include distillation, adsorption, and
extraction. Product(s) may be recovered from the solid by stripping
with steam, carbon dioxide, or other means.
[0033] The following are nonlimiting examples of the invention:
EXAMPLE 1
[0034] Metal Oxide/Zeolite composite MZ1 was prepared as follows: A
solid mixture of a ZSM-5-type zeolite (Zeolyst CBV 8014, Si/Al
ratio=80, 10 g, 170 mmoles SiO.sub.2) and CaNO.sub.3 nonahydrate (9
g, =34 mmoles Ca) was prepared and water was added to incipient
wetness. After CaNO.sub.3 dissolution and stirring, the slurry was
dried and calcined in sequence at 115.degree. C. (overnight) and
500.degree. C. (overnight), respectively, in air.
EXAMPLE 2
[0035] Methane at 15 psia was bubbled through bromine at 1.degree.
C. at a rate of 5 cc/min. The resulting stream of bromine and
methane (1:10 by mole) was passed through a small diameter
bromination reactor at 450.degree. C. (1000 h.sup.-1) and the
mixture of CH.sub.4-xBr.sub.x (x=0, 1, 2, 3) passed into a reactor
containing 5 g of metal oxide/zeolite composite MZ1 (400.degree.
C.). The output stream from the second reactor contained no
brominated products. Based on the methane consumed in the
bromination reactor, 10% ethylene, 31% propylene, 3% propane, and
21% butanes/butenes were detected; 65% overall. Trace amounts of
C.sub.6 species were also detected. After reaction for 5 hours,
during which the stream output did not change from the distribution
described above, the methane stream was discontinued and the
reactor was purged with helium at 5 cc/min for 10 minutes. After He
purge, a flow of O.sub.2 (2 cc/min) into the second reactor was
initiated at 525.degree. C. to regenerate the metal oxide from the
metal bromide of the partially spent composite. Initially only
water and CO.sub.2 were observed as products, but abruptly the
stream contents changed to Br.sub.2 and unreacted O.sub.2. After 1
hour, the O.sub.2 purge was discontinued and the reactor was again
purged with helium. The caustic trap used during regeneration was
tested for CO.sub.3.sup.-2 and 1.0 mmol was found, representing 24%
of the converted carbon. The remainder of carbon was found to be
higher boiling volatile aromatics (mostly toluene, xylenes and
mesitylenes). A second cycle of bromomethanes condensation as
described above was initiated at 400.degree. C. and the product
distribution was found to be identical to the first run. Three more
cycles of condensation/neutralization/regeneration produced the
same output of higher hydrocarbons.
EXAMPLE 3
[0036] A doped mordenite (Zeolyst CBV 21A, doped with both Ca and
Mg). (5 g) was prepared according to Example 1, and used as the
cataloreactant in a hydrocarbon synthesis substantially similar to
that described above in Example 2. The product output was 30%
ethylene, 5% ethane, 10% propylene, 3% propane, 5% butanes/butenes.
Multiple runs and cataloreactant regeneration established
reproducibility.
[0037] The invention has been described by reference to various
examples and preferred embodiments, but is not limited thereto.
Other modifications and substitutions can be made without departing
from the scope of the invention. For example, the oligomerization
processes described herein are also intended to encompass
halogenation of olefin feedstocks using a hydrogen halide (e.g.,
HBr) or molecular halogen; halogenation of acetylenes (alkynes)
using hydrogen halide or molecular halogen; halogenation of
alcohols or ethers using hydrogen halide or molecular halogen; and
halogenation of alkanes using molecular halogen and a catalyst that
controls the halogenation. Specifically, the catalyst may control
one or both of the degree of halogenation (number of halogens per
molecule) and the position of halogenation (e.g. terminal vs.
internal halogenation for a long chain alkane). Other modifications
may be made as well. The invention is limited only by the appended
claims and equivalents thereof.
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