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US006500313B2
(12) United States Patent
Sherwood
(10) Patent No.:
(45) Date of Patent:
US 6,500,313 B2
Dec. 31, 2002
OTHER PUBLICATIONS
(54) METHOD FOR PRODUCTION OF
HYDROCARBONS
(76) Inventor: Steven P. Sherwood, 10182 Foxridge
Cir., Highlands Ranch, CO (US) 80126
5,214,226 A
5,328,575 A *
5,414,176 A
6,077,492 A *
5/1993 Bauer et al. 585/658
7/1994 Geiger 204/157.15
5/1995 Amariglio et al. 585/500
6/2000 Anpo et al. 423/239.1
(56) References Cited
U.S. PATENT DOCUMENTS
Related U.S. Application Data
(60) Provisional application No. 60/257,265, filed on Dec. 19,
2000.
(51) Int. CI? C07C 1/00
(52) U.S. Cl. 204/157.15
(58) Field of Search 204/157.15
US 2002/0175067 A1 Nov. 28, 2002
Appl. No.: 09/837,000
Filed: Apr. 17, 2001
Prior Publication Data
ABSTRACT
(List continued on next page.)
A method for converting methane, ethane, and propane into
higher molecular weight hydrocarbons and coproduct
hydrogen wherein a molecular oxidant-free gas comprising
methane, ethane, and/or propane is exposed to ultraviolet
light. Through an oxidative coupling mechanism, the feed
gases are converted to free radicals which combine to form
higher molecular weight hydrocarbons.
2 Claims, 1 Drawing Sheet
(57)
Mleczko et aI., "Catalytic Oxidative Coupling of Methane-
Reaction Engineering Aspects and Process Schemes",
Fuel Processing Technology, vol. 42, pp. 217-248. (no
month available) 1995.*
Erarslanoglu et aI., "Oxidative Coupling of Methane on
Superconductor-Type Catalytic Materials", Chern. Eng.
Comm., vol. 135, pp. 71-79. (no month available) 1995.*
Pugsley et aI., "The Circulating Fluidized Bed Catalytic
Reactor: Reactor Model Validation and Simulation of the
Oxidative Coupling of Methane", Chern. Engin. Sci., vol.
51, No. 11, pp. 2751-2756. (no month available) 1996.*
Do et aI., "The Catalytic Oxidative Coupling of Methane: I.
Comparison of Experimental Performance Data from Various
Types of Reactor", The Canadian J. Chern. Engin., vol.
73, pp. 327-336. Jun. 1995.*
Ogura et aI., "Photochemical Conversion of Methane", J. of
Molecular Catalysis, vol. 43, pp. 371-379. (no month available)
1988.*
Okabe et aI., "Vacuum Ultraviolet Photolysis of Ethane:
Molecular Detachment of Hydrogen", J. of Chern. Phys.,
vol. 34, No.2, pp. 668-669. Feb. 1960.*
Primary Examiner-Edna Wong
(74) Attorney, Agent, or Firm---8heridan Ross Pc.
1/1928 Bird 585/416
7/1928 Olivier 585/500
5/1934 Steigerwald et al. 260/168
1/1935 Winkler et al. 260/168
1/1936 Reinecke 204/31
11/1936 Smith et al. 260/170
4/1984 Jones et al. 585/500
9/1987 Hall et al. 585/417
11/1987 Devries et al. 585/415
11/1987 Gondouin 585/500
1/1988 Withers 585/500
9/1988 Gastinger et al. 585/500
11/1988 Gaffney 585/500
1/1989 Gaffney et al. 585/500
5/1989 Hazbun 585/443
9/1989 Han et al. 585/943
11/1990 Allenger et al. 585/310
10/1991 Nikravech et al. 585/500
3/1993 Kaminsky et al. 585/500
Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.c. 154(b) by 0 days.
1,656,813 A
1,677,363 A
1,958,648 A
1,986,238 A
2,028,014 A
2,061,598 A
4,444,984 A
4,695,663 A
4,704,488 A
4,705,908 A
4,721,828 A
4,769,508 A
4,788,372 A
4,795,849 A
4,827,071 A
4,864,073 A
4,973,776 A
5,053,575 A
5,198,596 A
( *) Notice:
(21)
(22)
(65)
US 6,500,313 B2
Page 2
OlliER PUBLICATIONS
Ausloos et aI., "Direct and Inert-Gas-Sensitized Radiolysis
and Photolysis of Methane in the Solid Phase", J. of Chern.
Phys., vol. 42, No.2, pp. 540-548. Jan. 1964.*
Ausloos et aI., "Radiolysis of Methane", J. of Chern. Phys.,
vol. 38, No.9, pp. 2207-2214. May 1963.*
Ausloos et aI., "Effect of Pressure in a Radiolysis and
Photolysis of Methane", J. of Chern. Phys., vol. 40, No.7,
pp. 1854-160. Apr. 1964.*
Mahan et aI., "Vacuum Ultraviolet Photolysis of Methane",
J. of Chern. Phys., vol. 37, No.2., pp. 207-211. Jul. 1962.*
Leighton et aI., "Photochemical Decomposition of Methane",
J. of Amer. Chern. Soc., Communications to the Ed.,
p. 1823. (no month available) 1936.*
Mordaunt et aI., "Primary Product Channels in the Photodissociation
of Methane at 121.6nm", J. Chern. Phys., vol.
98, No.3, pp. 2054-20-65. Feb. 1993.*
Wu et aI., "Site Specificity in Molecular Hydrogen Elimination
From Photodissociation of Propane at 157 nm",
Communications, vol. 111, No.5, pp. 1793-1796. (no month
available) 1999.*
Heck et aI., "Photofragment Imaging of Methane", J. Chern.
Phys., vol. 104, No. 11, pp. 4019-4030. Mar. 1996.*
Irle et aI., "A Molecular Orbital Study on Hand H2
Elimination Pathways From Methane, Ethane, and Propane",
J. Chern Phys., vol. 113, No. 15, pp. 6139-6148. Oct.
2000.*
Ellis et aI., The Chemical Action of Ultraviolet Rays,
Chapter 22, pp. 393-395. (no month availabel) 1941.*
*References U-X were incompletely cited on Applicants'
Information Disclosure Statement (paper No. 2).*
Irle et aI., 2000, J. Chern. Phys., 113(15):6139-6148, No
month available.
Heck et aI., 1996, J. Chern. Phys., 104(11):4019-4030, No
month available.
Wu et aI., 1999, Communications, 0021-9606/99/
111(5):1793-1796, No month available.
Mordaunt et aI., J. Chern. Phys., 98(3):2054-2065 Feb.
1993.
Okabe, in Photochemistry ofSmall Molecules, John Wiley &
Sons, New York, pp. 298-299 No month available.
Ellis et aI., in Chemical Action of Ultraviolet Rays, Chapter
22, F. Heyroth, ed., Reinhold Publishing Corporation, New
York, 1941, pp. 393-395, No month available.
Noyes, Jr. et aI., The Photochemistry of Gases, F. Heyroth,
ed., Reinhold Publishing Corporation, New York, 1941, pp.
330-331+ Appendices.
Leighton et aI., Sep. 1936, J. Am. Chern. Soc., Communications
to the Ed., p. 1823, No month available.
Mahan et aI., 1962, J. Chern. Phys., 37(2):207-211, No
month available.
Ausloss et aI., 1963, J. Chern. Phys., 38(9):2207-2214, No
month available.
Ausloos, 1964,J. Chern. Phys., 40(7):1854-1860, No month
available.
Ausloos et aI., 1964, J. Chern. Phys., 42(2):540-548, No
month available.
Okabe et aI., 1960, J. Chern. Phys., 34(2)668-669, No
month available.
Barltrop et aI., in Excited States in Organic Chemistry, John
Wiley & Sons, London, p. 335 No date available.
Calvert et aI., Photochemistry of the Polyatomic Molecules,
492-579 No date available.
Ogura et aI., 1988, Journal of Molecular Catalysis, 43,
371-379 No month available.
Do et al:, 1995, The Canadian Journal of Chemical Engineering,
73, 327-336, No month available.
Pugsley et aI., Chemical Engineering Science, 1996,51(11),
2751-2756, No month available.
Erarslanoglu et aI., Chemical Engineering Comm., 1995,
135,71-79, No month available.
Mleczko et aI., Fuel Processing Technology, 1995, 42,
217-248, No month available.
* cited by examiner
u.s. Patent
cess
Outlet
Fic1ure 1 b
Dec. 31, 2002
s
".;..".';' ; ,.
Heat
US 6,500,313 B2
Outlet
US 6,500,313 B2
2
of ultra violet radiation, a photocatalyst (optionally), and in
the absence of molecular oxidants. Accordingly, the present
invention provides a process for producing liquids containing
hydrocarbons of a higher molecular weight than methane
5 comprising bringing into contact in the vapor phase a
hydrocarbon feedstock, such as one containing a major
proportion of methane, and optionally, a photocatalyst composition
in the presence of ultraviolet radiation and in the
absence of molecular oxidants.
Photocatalytic reactions using the titanium oxide catalyst
have been the focus of research as an environmentallyfriendly
and safe means of converting light energy into
useful chemical energy at ordinary temperatures without
generating any pollutants. Other photocatalysts, such as
45 platinum, can be used as well. Photocatalytic reactions
proceed when the reaction systems are irradiated with
ultraviolet-light in wavelength regions shorter than about
380 nm necessitating the use of an ultraviolet light source.
Preferably, the ultraviolet radiation is provided at a wave-
50 length of about 150 nm to about 280 nm.
The feedstock gas may be maintained at an increased
pressure to increase molecular interactions with the gas and
thereby decrease the necessary reaction time. Although the
reaction will proceed within a feedstock gas maintained as
55 less than atmospheric pressures, preferably the feedstock gas
is maintained at a pressure greater than about 4psig during
the exposure to the ultraviolet radiation.
The reaction may occur in any reaction vessel which
provides sufficient contact between the ultraviolet light and
60 the feedstock gas and in the absence of molecular oxidants.
In one embodiment, the reaction is conducted in a tube
reactor into which the light source has been fitted in the
annular space. The reactor has an inlet and outlet valve and
a jacket providing for the exchange of a temperature con-
65 trolling liquid. The ultraviolet lamp may be a standard
Pen-Ray lamp (UVP Products) fitted with a fused quartz
envelop which does not allow for the transmittance of the
The hydrocarbon feedstock can have at least 50% w/w,
preferably at least 70% w/w of methane, more preferably at
least 90% w/w and may be admixed with other molecular
weight hydrocarbons such as ethane or propane. The additional
hydrocarbon in the feedstock, if any, may include
15 ethane, ethylene, propane, propylene or mixtures thereof.
The feedstock may contain in addition, other open chain
hydrocarbons containing between 3 and 8 carbon atoms as
coreactants. Specific examples of such additional coreactants
are propane, propylene, n-butane, isobutane, n-butenes
20 and isobutene. Suitable feedstock gas may include methane,
natural gas, off gas from decomposing biomass, methane
from coal mines, and waste methane gas from chemical
processes.
The hydrocarbon feedstock is thereafter contacted in the
25 vapor phase with light in wavelength regions of about 150
nm to about 280 nm, i.e., ultra-violet radiation, and in the
absence of molecular oxidants. The reaction is preferably
conducted at a temperature between about 0° C. and about
800° c., preferably above about 60° C. The reaction is
30 preferably conducted in an inert atmosphere. The inert
atmosphere may be provided by a gas inert under the
reaction conditions such as nitrogen. In fact, once the reactor
has been initially flushed with an inert gas such as nitrogen
to remove any oxygen or oxidising gases, there is no need
35 to add further amounts of the inert gas to the reaction system.
Any unreacted hydrocarbon feedstock and by-products
recovered from the reaction products may be recycled to the
reaction.
FIELD OF THE INVENTION
DETAILED DESCRIPTION OF THE
INVENTION
1
METHOD FOR PRODUCTION OF
HYDROCARBONS
BACKGROUND OF THE INVENTION
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 shows a schematic of the tube reactor that may be
used in one embodiment of the present invention.
The present invention provides an coupling process which
does not require oxygen or any other oxidant thereby
eliminating the conversion of methane to carbon dioxide. In
this new process, methane is converted to a methyl radical
and a hydrogen radical by exposing the gas to ultraviolet
radiation. The formation of these free radicals is confirmed
by the presence of ethane and H2 in the reaction product gas.
These molecules are produced when two methyl radicals
combine to produce ethane and two hydrogen radicals
combine to form H2 .
It has now been found that higher molecular weight
hydrocarbons can be produced from lower molecular weight
hydrocarbon feedstocks, and particularly those containing
predominately less than three carbon atoms in the presence
The present invention relates to a process for producing 10
liquids containing hydrocarbons of a higher molecular
weight than methane from a hydrocarbon feedstock containing
a major proportion of methane.
This application claims the benefit of Provisional Patent
Application Serial No. 60/257,265 filed in the U.S. Patent
and Trademark Office on Dec. 19, 2000.
Gas-to-liquid conversion technologies use chemical
means to convert methane or natural gas to a liquid form
suitable for ready transport or direct use. This conversion is
accomplished by altering the composition of the hydrocarbon
gas molecules to form stable liquids that can be used
directly as a chemical feedstock or transportation fuel. There
are two known approaches to accomplish this conversion;
partial oxidation and oxidative coupling. In the partial
oxidation process, hydrocarbons, oxygen and/or water are
converted to a synthetic gas containing molecular hydrogen
and carbon monoxide. These constituents are recombined in
a second process to produce paraffins and high molecular
weight fuels such as diesel fuel and heating oil. In the
oxidative coupling reaction, hydrocarbon gases are directly
converted into desirable liquid hydrocarbons through a
series of free radical addition mechanisms.
Known oxidative coupling technologies use oxygen to
convert methane to the methyl free radical and water in the
presence of a catalyst at temperatures of 800 to 1000° C. The
major challenge of these technologies is the rapid conversion
of the radicals to carbon dioxide before the radicals can
link-up, greatly limiting the conversion to higher molecular
weight compounds.
Previous synthetic routes to producing higher molecular
weight hydrocarbons from lower molecular weight hydro- 40
carbons have started from feedstocks which have at least
two carbon atoms. Such feedstocks are initially dimerised or
oligomerised at temperatures in the region of 500-600° C.
Such processes are described, for example, in U.S. Pat. Nos.
1,677,363; 4,721,828; 4,769,828; and 5,414,176.
US 6,500,313 B2
3 4
Fourth
Day After
Air Spike
Third
Day After
Air Spike
Mole Percent in Product Gas
8-Day UV
Exposure
-No Air
32 25 25
59 57 53
0.25 3.3 3.9
Higher Molecular Weight Hydrocabons from C2 to
C12 in Product Gas
What is claimed is:
1. A method of producing hydrocarbon material, comprising:
After eight days of exposure to vacuum UV radiation,
approximately 40 mole percent of the initial methane charge
was converted to hydrogen and higher molecular weight
hydrocarbons. Hydrocarbons containing up to 12 carbons
were found in the product gas mixture. The introduction of
a small amount of air consumed hydrogen and increased the
carbon dioxide levels in the product gas. The air spike also
reduced the rate of methane conversion from approximately
5% per day to less than 2% per day.
Analyte
methane (CP grade) and the gas exposed to UV radiation at
a controlled temperature of 60° C. After eight days of UV
exposure, a sample of process gas was taken for analysis and
the reaction mixture spiked with a small amount of air, and
5 the process gas resampled three and four days later. Results
from these tests are provided in the following table.
15 Hydrogen
Methane
Carbon Dioxide
GCjMS Analysis
EXAMPLES
vacuum UV (minus 200 nm) mercury spectral emission, or
a UV lamp fitted with a special quartz envelop which
permits transmittance of the ultraviolet light. Preferably, the
source of ultraviolet radiation permits more than 80% transmittance
of the vacuum ultraviolet light.
The level of oxygen in the present process is maintained
as low as possible to reduce the production of oxygenated
products that ultimately interfere with the radical reaction
thereby decreasing performance. Preferably, oxygen is
maintained at a level of less than about 5%, more preferably
less than about 3%, and most preferably less than about 1% 10
in the reaction feedstock.
The higher molecular weight hydrocarbons are recovered
by condensing the products to a liquid in an air or liquid
chilled cooling vessel. Hydrogen gas is recovered with a
hydrogen specific membrane.
A series of batch studies were conducted to examine
efficiencies of two types of ultraviolet lamp for the conversion
of methane to hydrogen and higher molecular weight
hydrocarbons. One UV source investigated was a standard 20
Pen-Ray lamp (UVP Products Cat. No. 90-0004-01). This
lamp was fitted with a fused quartz envelop which does not
allow for the transmittance of the vacuum UV (minus 200
nm) mercury spectral emission. The second UV lamp was
fitted with a special quartz envelop which permitted more 25
than 80% transmittance of the vacuum UV light.
In these tests, the selected UV lamp source was placed in
the annular space of a lh-inch diameter stainless steel
jacketed tube reactor. A schematic of the tube reactor is
provided in FIG. 1. A cooling or heated solution was 30
recirculated through the heat exchanger jacket to maintain
targeted temperatures. During these tests the reactor was
charged with 30 psig methane (CP Grade) and the stagnant
gas exposed to UV light for 18 hours. At the conclusion of
each test, the product gas was analyzed by hydrogen content
(GC analysis). Results from these studies are summarized in 35
the following table.
40
45
exposing a feedstock comprising methane in vapor phase
maintained at a temperature greater than about 400° C.
to ultraviolet radiation having a wavelength in the
range of about 150nm to about 280 nm, in the absence
of a molecular oxidant to produce higher molecular
weight hydrocarbons; and
recovering a hydrocarbon material having a higher
molecular weight than said methane.
2. A method of producing hydrocarbon material, compris50
ing;
exposing a feedstock comprising methane in vapor phase
maintained at a pressure of greater than about 4 psig to
ultraviolet radiation having a wavelength in the range
of about 150 nm to about 280 nm, in the absence of a
molecular oxidant to produce higher molecular weight
hydrocarbons; and
recovering a hydrocarbon material having a higher
molecular weight than said methane.
Not Tested
Not Tested
0.911
Not Tested
Not Tested
0.319
3.9
4.03
Special Quartz Envelop
Lamp (80% Transmittance
of Vacuum UV)
0.069
0.097
0.240
0.368
0.635
Not Tested
0.310
Not Tested
Mole Percent Hydrogen in Reaction Gas Mixture
Standard Quartz Envelop
Lamp
(Minimal Vacuum UV)
Batch 18 Hour UVrremperature Study
These results show that highest hydrogen production was
achieved when methane was exposed to vacumm UV (minus 55
200 nm) radiation at a reaction temperature of 60° C.
Effect of Long Exposure Time and Air (Oxygen)
on Vacuum UV Process
Reaction
Temperature, 0 c.
10
15
20
30
40
50
60
60 (Rerun)
To determine the long-term effectiveness of the special
quartz process, the tube reactor was charged with 10 psig * * * * *