U.S. patent application number 12/111780 was filed with the patent office on 2008-12-04 for system for the production of synthetic fuels.
Invention is credited to Allen W. Boykin, Jack W. Boykin.
Application Number | 20080295390 12/111780 |
Document ID | / |
Family ID | 39943907 |
Filed Date | 2008-12-04 |
United States Patent
Application |
20080295390 |
Kind Code |
A1 |
Boykin; Jack W. ; et
al. |
December 4, 2008 |
SYSTEM FOR THE PRODUCTION OF SYNTHETIC FUELS
Abstract
A system and method for producing synthetic fuels are disclosed
in which a slurry comprised of a particulate solid portion and a
carrier liquid portion is provided. The solid portion comprises (i)
a feedstock of carbon-containing polymeric materials that are
substantially free of each of halogen, sulfur and nitrogen atoms,
and contain about 5 to about 25 percent by weight water, and (ii) a
catalytic amount of metal particles. The carrier liquid portion is
a hydrocarbon/oxyhydrocarbon composition. The feedstock constitutes
about 10 to about 60 weight percent of the slurry. The slurry is
heated anaerobically to provide an elevated temperature of about
250.degree. to about 455.degree. C. and a pressure of about 20 to
about 50 atmospheres that are maintained for a time period
sufficient to provide a combustible liquid fuel at least 80 percent
of which contains about 6 to about 21 carbon atoms per
molecule.
Inventors: |
Boykin; Jack W.; (Montrose,
AL) ; Boykin; Allen W.; (Daphne, AL) |
Correspondence
Address: |
Husch Blackwell Sanders, LLP;Welsh & Katz
120 S RIVERSIDE PLAZA, 22ND FLOOR
CHICAGO
IL
60606
US
|
Family ID: |
39943907 |
Appl. No.: |
12/111780 |
Filed: |
April 29, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11768097 |
Jun 25, 2007 |
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12111780 |
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11768057 |
Jun 25, 2007 |
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11768097 |
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11768073 |
Jun 25, 2007 |
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11768057 |
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60927552 |
May 4, 2007 |
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Current U.S.
Class: |
44/307 |
Current CPC
Class: |
C10L 1/02 20130101; B01J
2219/00006 20130101; B01J 2219/0004 20130101; C10G 1/10 20130101;
C10G 50/00 20130101; C10L 1/04 20130101 |
Class at
Publication: |
44/307 |
International
Class: |
C10L 1/18 20060101
C10L001/18 |
Claims
1. A method of producing a combustible liquid fuel that comprises
the steps of: a) providing a slurry comprised of a particulate
solid portion and a carrier liquid portion, said solid portion
comprising (i) a feedstock of carbon-containing polymeric materials
that are substantially free of each of halogen, sulfur and nitrogen
atoms, said feedstock containing about 5 to about 25 percent by
weight water, (ii) a catalytic amount of Group VIII, IB, IIB, IIIA,
or IVA metal particles comminuted to pass through a No. 18 Standard
Sieve, and (iii) a carrier liquid portion that is a
hydrocarbon/oxyhydrocarbon composition, wherein the feedstock
constitutes about 10 to about 60 weight percent of said slurry and
said hydrocarbon/oxyhydrocarbon composition having the viscosity
and boiling characteristics of gasoline to lubricating oil; b)
heating the slurry anaerobically to provide an elevated temperature
of about 250.degree. to about 455.degree. C. and a pressure of
about 20 to about 50 atmospheres; c) maintaining said elevated
temperature and pressure for a time period sufficient to provide a
combustible liquid fuel at least 80 percent of which contains about
6 to about 21 carbon atoms per molecule, whereby maintenance at
higher temperature and pressure for a constant time period lead to
a product containing fewer carbon atoms per molecule as does
maintenance at a constant temperature and pressure with a longer
period of time.
2. The method according to claim 1, wherein the particulate
feedstock carbon-containing polymeric materials are comprised of
biomass including one or both of a cellulosic material and
lignin.
3. The method according to claim 1, wherein the one or both of a
cellulosic material and lignin are provided by a source selected
from the group consisting of wood chips, sawdust, brush, hay,
straw, switch grass, corn stalks, kudzu, paper and cardboard, and
mixtures thereof
4. The method according to claim 1, wherein the particulate
feedstock carbon-containing polymeric materials are comprised of a
synthetic polymer.
5. The method according to claim 4, wherein the synthetic polymer
is a rubber.
6. The method according to claim 5, wherein the comminuted metal
particles and the rubber synthetic polymer are provided by
comminuted tires.
7. The method according to claim 6, wherein 80% or more of the
comminuted tires have a largest dimension of less than about 500
microns.
8. The method according to claim 6, wherein the particulate
feedstock pieces comprise shredded tire particles, 80% or more of
which have a largest dimension of less than about 300 microns.
9. The method according to claim 1, wherein at least 80 percent of
said combustible liquid fuel is comprised of molecules that contain
about 6 to about 12 carbon atoms per molecule.
10. The method according to claim 1, wherein at least 80 percent of
said combustible liquid fuel is comprised of molecules that contain
about 12 to about 21 carbon atoms per molecule.
11. The method according to claim 1, wherein at least 80 percent of
said combustible liquid fuel is comprised of molecules that contain
about 15 to about 19 carbon atoms per molecule.
12. The method according to claim 1, wherein the particulate
feedstock carbon-containing polymeric materials are comprised of
biomass including one or both of a cellulosic material and lignin
in combination with ground tire particles.
13. The method according to claim 1, wherein the catalytic metal
particles are comprised of one or more Group VIII metals.
14. The method according to claim 13, wherein the catalytic metal
particles are comprised of iron.
15. The method according to claim 1, wherein at least about 80% of
the catalytic metal particles are sized to pass through a No. 35
Standard Sieve.
16. The method according to claim 1, wherein at least about 80% of
the catalytic metal particles are sized to pass through a No. 50
Standard Sieve.
17. The method according to claim 1, wherein a portion of the
combustible fuel produced is recycled to provide part of the
carrier liquid portion of the slurry.
18. The method according to claim 1, wherein the metal particles
are present at about 1 to about 10 weight percent of the
feedstock.
19. The method according to claim 18, wherein the metal particles
are present at more than about 5 weight percent of the
feedstock.
20. The method according to claim 1, wherein the particulate
feedstock carbon-containing polymeric materials are comprised of a
mixture of cellulosic material and synthetic polymer.
21. The method according to claim 1, wherein the feedstock contains
about 15 to about 20 percent by weight water
22. The method according to claim 1, including the additional step
of using shock waves to break up long chain polymers into shorter
chain polymers
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of each of
application Ser. No. 11/768,097, Ser. No. 11/768,057 and Ser. No.
11/768,073 that all were filed on Jun. 25, 2007 and claim priority
to provisional application Ser. No. 60/927,552 filed on May 4,
2007, the contents of which are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] Wood and coal have been a principle source of fuel for
hundreds of years. In modern times, petroleum has become a primary
commodity for the generation of energy. Petroleum has had the
advantages of relatively low cost and ease of transportation and
storage because of its liquid consistency. Further, petroleum is
readily amenable to fractionation and conversion into a variety of
valuable industrial products such as fuels, building products,
chemical intermediates and the like.
[0003] International developments have led to increase in the price
of this crude oil. The consumption of petroleum has been increasing
exponentially and concomitantly the readily available world
petroleum supply has diminished. Governments and industrial
concerns are dedicating increased attention to alternatives to
petroleum as sources for fuels and chemical intermediates.
[0004] In recent years, the world has seen many innovations in
"green" technologies, including methods for making synthetic fuels
for transportation and heat utilizing the enzymatic and bacterial
decomposition of cellulose and starch material to ethanol or
similar alkanol products. Vegetable oils of many varied plant
sources have been converted to alkyl esters. Although these
processes are clean and environmental friendly and can provide an
alternative source of synthetic fuel, the use of edible plants
inevitably leads to the increase of price for food supply.
Moreover, many of these plants require high energy costs during the
planting, harvesting and processing phases.
[0005] New programs are being developed for the provision of
carbonaceous fuel products which complement and enhance
conventional petroleum or coal-derived energy sources. Processes
for liquefying coal or the gasification and then condensation of
other carbon-containing materials have been proposed. However,
these processes have not been deemed to be fully satisfactory for
various cost or environmental reasons. There remains a pressing
need for new technology that can deliver high quality fuels at
economically and environmentally favorable levels, while
maintaining atmospheric carbon neutrality.
[0006] Accordingly, it is desirable to provide a system and process
of producing liquid synthetic fuels that overcomes drawbacks of
conventional systems and methods of producing synthetic fuel.
[0007] Other objects and advantages of the present invention shall
become apparent from the accompanying description and examples.
BRIEF SUMMARY OF THE INVENTION
[0008] In accordance with the invention, a system and method for
producing synthetic fuels, especially those that are essentially
chemically identical to conventional vehicle fuels, is provided in
which a feedstock comprised of carbon-containing polymers from one
or more of a wide variety of sources is re-formed into a more
satisfactory liquid fuel source for producing heat, electricity,
powering vehicles and the like. The feedstock can comprise scrap
rubber, plastic and/or organic matter or other materials that are
not particularly well suited for use as fuels in their existing
state.
[0009] The system and method contemplate breaking relatively long,
usually solid carbon-containing synthetic polymer and/or natural
polymer molecules of a feedstock into shorter carbon chain moieties
and then polymerizing or otherwise reforming those short chain
moieties and forming a liquid fuel comprising a mixture of
compounds comprised of hydrocarbons such as straight, branched and
mono- and polycyclic alkanes, alkenes, and alkynes, as well as
oxygenated hydrocarbons such as alcohols, ketones, aldehydes,
carboxylic acids, ethers and esters of selected length. This
mixture of fuel components is collectively referred to as
hydrocarbon/oxyhydrocarbon compounds. The words "solid" and
"liquid" refer to physical states at ambient room temperature;
i.e., about 20.degree. C., and one atmosphere of pressure.
[0010] Reactions in accordance with preferred embodiments of the
invention do not involve a net addition of oxygen to the system,
can be considered anaerobic, and usually remove oxygen present from
the polymer. A reaction in accordance with preferred embodiments of
the invention usually utilizes much less water than many
conventional methods.
[0011] A process in accordance with a preferred embodiment of the
invention typically utilizes physical reduction of the size of the
various solid components; drying or wetting those components to a
controlled water level; liquefying reactions where components are
broken down to form shorter chained moieties; removal of oxygen
atoms from carbohydrates and/or saturation of unsaturated bonds
from hydrocarbon compounds; and recombination of formed short chain
species to form molecules having predetermined, desired numbers of
carbon atoms to make synthetic fuels that include one or both of
hydrocarbons or oxygenated hydrocarbons.
[0012] A feedstock in accordance with the invention can include a
wide variety of sources of biomass including one or both of lignin
and a naturally occurring polysaccharide material such as cellulose
and hemicellulose polymers, as well as one or more synthetic
carbon-containing polymeric materials. It is preferred that the
feedstock be provided reduced in size, into particles that are
preferably less than about 1,000 microns in the largest dimension,
more preferably less than about 500 microns and most preferably
less than about 300 microns. This size reduction can be done in
multiple stages with the final reductions in size preferably
carried out with the feedstock as a solid component dispersed in an
organic liquid carrier that is a hydrocarbon/oxyhydrocarbon
composition to form a slurry.
[0013] The weight percentage of feedstock in the slurry can be
about 10% to about 60%, with percentages of about 40% to about 50%
being preferred. The liquid for the slurry is preferably a
hydrocarbon/oxyhydrocarbon composition such as the recycled
hydrocarbon/oxyhydrocarbon fuel product from the synthetic fuel
process. However, other liquids such as No. 2 diesel fuel are also
useful.
[0014] The particulate, polymeric feedstock is combined with a
metal catalyst or initiator, such as a Group VIII, IB, IIB, IIIA,
IVA metal or in particular, platinum, iron, aluminum, zinc, copper
and the like. The catalyst is present in an amount of up to about
10 percent by weight of the feedstock. A preferred source of the
metal catalyst comes from ground up automobile tires.
[0015] The feedstock/catalyst mixture dispersed in a liquid as a
slurry is subjected to the controlled application of high
temperature and pressure to liquefy and reform the feedstock. High
temperature and pressure can be used to help break feedstock
polymer molecules into short chain moieties, that contain 2- to
about 9-carbon atoms. Most, if not all of the original oxygen
present in the carbon-containing polymeric feedstock is removed
during the reforming process. The short chain hydrocarbons are
advantageously combined into hydrocarbons/oxyhydrocarbons of a
predetermined, selected carbon content; i.e., average number of
carbon atoms in molecules of the resulting mixture.
[0016] Processes in accordance with the invention are preferably
conducted in substantially airtight conditions. It is preferred to
put the feedstock into a non-aqueous slurry, with the liquid phase
comprising a hydrocarbon/oxyhydrocarbon composition that has the
viscosity and boiling characteristics of gasoline (boiling range at
1 atmosphere of 40 to about 205.degree. C.) to those of lubricating
oil (boiling range of about 300 to about 370.degree. C.). A
particularly preferred hydrocarbon/oxyhydrocarbon composition is
No. 2 diesel fuel (boiling range of about 285.degree. to about
340.degree. C.) or an oxygen-containing hydrocarbon such as an
ester such as butyl phthalate or butyl sebacate, having a similar
boiling point to the diesel fuel.
[0017] In a preferred embodiment of the invention, the chemical
reactions take place in an organic liquid phase. The
hydrocarbon/oxyhydrocarbon output of reactions in accordance with
the invention can be recycled and used as the organic liquid, such
as that combined with the initial feedstock, to ensure a
substantially air free system and to assist in the downsizing of
the feedstock solids. The recycled hydrocarbon/oxyhydrocarbon
output is at elevated temperature. Thus, the recycled stream can
aid in the initial elevation of feedstock temperature and reduces
instances of charring. Recycling the output can also lead to
branched chain hydrocarbons, which tend to increase octane or
cetane ratings of the fuels produced.
[0018] The invention can be carried out using multiple reactors,
with three as a preferred number. In a first reactor, the feedstock
can be substantially, at least about 80%, liquefied. This
liquification can involve breaking intermolecular and
intramolecular bonds and reducing the size of the feedstock
molecules and polymers. The output temperature is about 250.degree.
F. (121.degree. C.) to about 450.degree. F. (230.degree. C.), and
the pressure is about 5 to about 15 atmospheres. In a second
reactor, additional bonds are advantageously broken and the
feedstock material can be transformed into shorter chain moieties.
Deoxygenation takes place to replace hydroxyl groups with hydrogen.
The output temperature is about 500.degree. F. (260.degree. C.),
with a pressure of about 25 atmospheres. Finally, those moieties
can be formed into polymerized or otherwise reformed hydrocarbons
and oxyhydrocarbons of predetermined selected length (number of
carbon atoms) in the third reactor, the output temperature of which
is about 700.degree. F. (370.degree. C.) to about 850.degree. F.
(455.degree. C.) and a pressure of about 30 to about 55
atmospheres.
[0019] Preferred reactors are in the form of horizontal tubes. The
tubes are preferably formed of steel, stainless steel or other
appropriate metal that can withstand the temperatures and pressures
of the reaction without substantial degradation. The tubes are
capable of containing liquid at about 850.degree. F. (455.degree.
C.) and a gauge pressure of about 55 atmospheres. An internal screw
is preferably used to move the reactants in plug-flow, through the
reactor at controlled speeds. Electrical heating elements on the
reactor surfaces advantageously control the temperature of the
reactors, although other sources of heating such as pressurized
steam, flame and the like are also contemplated. Measuring the
temperature and viscosity at the output can provide valuable
feedback for controlling the heating elements and screw speed.
[0020] It is believed that the metal particles in the slurry react
with the water in the feedstock to yield metal oxides and hydrogen.
At the temperatures involved, ranging from over about 250.degree.
F. (120.degree. C.) to 450.degree. F. (230.degree. C.) and above,
the free hydrogen is believed to attack (saturate) double bonds
created by the metal catalyst in the feedstock material. The metal
catalyst particles also assist in reducing the size of the
feedstock molecules and promote the liquefaction of the feed
stream. Increasing the temperature, either in the same or in a
separate reactor, further breaks down the feed material into small
chain hydrocarbon moieties, advantageously containing 2- to about
9-carbons. Molecular size of the reformed product can be
predetermined (adjusted) by controlling the temperature, pressure,
reactor time and the amount of metal added. Thus, at a constant
reaction time, increasing the temperatures from about 260.degree.
C. to about 425.degree. C. and pressures of about 20 to about 50
atmospheres provides a mixture of product compounds having about
equal amounts of C12 and C14-18 species, with small amounts of C6-8
species changing to a product mixture having significant amounts of
C6 species, major amounts of C8-12 species and almost no product
having 14-18 carbons. Shorter reaction times at the higher
temperatures and pressures provide more of the higher molecular
weight product species.
[0021] By adjusting reaction temperatures and pressures, at least
80% if not substantially all of the output can be gasoline, diesel
fuel or aircraft fuel. The bulk of a typical gasoline consists of a
mixture of hydrocarbons with between 5 and 12 carbon atoms per
molecule. On the other hand, No. 2 diesel fuel has a range of about
12 top about 21 carbon atoms per molecule, with some unsaturation
or ring structures present.
[0022] In another embodiment of the invention, the output can be
blended as more than least 5% or 10% with one of these fuels. The
resulting product can be used as is or further refined or purified.
It can also be advisable to employ a mechanism, such as a shockwave
producer, to break up any relatively long chain hydrocarbons, such
as waxes, that might be in the final product.
[0023] The invention accordingly comprises the several steps and
the relation of one or more of such steps with respect to each of
the others, the system embodying features of construction,
combinations and arrangement of parts which are adapted to effect
such steps, and the product which possesses the characteristics,
properties, and relation of constituents (components), all as
exemplified in the detailed disclosure hereinafter set forth, and
the scope of the invention will be indicated in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] For a fuller understanding of the invention, reference is
had to the following description, taken in connection with the
accompanying drawings, in which:
[0025] FIG. 1 is a schematic diagram of a system for producing
synthetic fuels, in accordance with preferred embodiments of the
invention;
[0026] FIG. 2 is a schematic diagram of a size reduction section of
the system of FIG. 1;
[0027] FIG. 3 is a schematic diagram of a reaction section of the
system of FIG. 1;
[0028] FIG. 4 is a schematic diagram of a finishing section of the
system of FIG. 1;
[0029] FIG. 5 is a chemical drawing of the chemical breakdown of
cellulose from biomass to aldotriose and/or aldohexose; and
[0030] FIG. 6 is a chemical drawing of bond cleavage when butadiene
containing tires are used.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0031] As discussed herein, a system and method are provided for
converting a carbon-containing polymeric feedstock comprised of
materials such as rubber, cellulosic and hemicellulosic and plastic
materials into a synthetic fuel such as a synthetic form of
gasoline, diesel, kerosene and home heating fuel, often referred to
herein as a "feedstock". The polymeric raw material is
depolymerized to low molecular weight intermediates and then
re-combined to a predetermined, controlled molecular weight mixture
of carbon-containing species, which is similar to the molecular
structures of gasoline, diesel or other fuel.
[0032] A contemplated process combines pressure, heat and chemical
catalysts. Specifically, the process combines the following general
steps: (i) size reduction process that reduces feedstock materials
to a low-micron level particle; (ii) liquefaction reactor system
which reduces the feedstock to short chain monomers; (iii) second
stage processing system which recombines the monomers into
synthetic gasoline (based on a 6-12 carbon chain molecule), diesel
fuel (based on a 12-21 carbon chain molecule), or jet fuel (based
on a 12-18 carbon chain molecule); and (iv) transfer and storage
tanks for final products. Processes and systems in accordance with
the invention can be used to produce about one gallon of synthetic
fuel from about 12 to 15 pounds of dry cellulose or plastic
polymer.
[0033] The process can be highly environmentally friendly. The
process can be anaerobic and anhydrous (non-aqueous carrier liquid)
which creates negligible amounts of carbon dioxide, a major
byproduct of many competing processes, and the anhydrous process
generates no wastewater.
[0034] Fuels produced can have boiling points of 300.degree. to
700.degree. F., room temperature viscosities of about 1 to about
200 cps and are suitable for a variety of uses.
[0035] FIG. 1 is a schematic view of a fuel production plant (10)
in accordance with a preferred embodiment of the invention. The
plant (10) comprises three general process sections: a size
reduction section (200), a reaction section (300) and a finishing
section (400), each shown in greater detail in FIGS. 2, 3 and 4,
respectively.
[0036] One preferred embodiment of the invention utilizes a size
reduction step having multiple stages to reduce, preferably
gradually, the size of the carbon-containing polymer feedstock to
the desired particle size. It is preferred that the feedstock be
present in the slurry in particulate form at a particle size of
about 1 inch (about 2.54 cm) in the longest dimension or less.
[0037] Referring to FIG. 2, size reduction section (200) preferably
comprises a first stage size reduction grinder (210), a second
stage size reduction grinder (220), a third stage size reduction
grinder (230), a fourth stage size reduction safety grinder (240)
and a slurry storage tank (250). Acceptable grinders in accordance
with preferred embodiments of the invention include the MultiShear
and Arde Barinco brand grinders, from MultiShear Corporation of
Graniteville, S.C. and Arde Barinco, Inc. of Norwood, N.J.
[0038] A size reduction process can begin when a truck or other
vehicle delivers a variety of feedstock to plant (10) or when the
materials are reduced in size off site. A feedstock (201) is placed
on a first conveyor belt (205), which carries the feedstock upon
unloading to first stage size reduction grinder (210). The output
of first stage size reduction grinder (210) is placed on a second
conveyor belt (215), which carries once-reduced feedstock (211) to
second stage size reduction grinder (220). Similarly, the
twice-reduced output 221 of second stage size reduction grinder
(220) is placed on a third conveyor belt (225) and transported to
third stage size reduction grinder (230). Optionally, a storage
tank, such as tank (235), can be added to store once-reduced output
(211) of first stage size reduction grinder (210) or twice-reduced
output (221) of second stage size reduction grinder (220). The
three times reduced output (231) from third stage size reduction
grinder (230) can be fed into fourth stage size reduction safety
grinder (240) to insure substantially complete size reduction
before a slurry output (241) is being stored in slurry storage tank
(250). Alternatively, output (231) can be stored in slurry storage
tank (250) without being fed into fourth stage size reduction
safety grinder (240). Safety grinder (240) is optionally attached
to slurry storage tank (250) to ensure uniformity of particles of
less than about 300 microns before the slurry enters the reaction
section (300).
[0039] One purpose of the size reduction process of section (200)
is to decrease the size of the feedstock pieces, preferably
gradually, to desirable sizes, preferably less than 300 microns. In
one embodiment, the feedstock is first ground to 1/2 inch to 1 inch
pieces in first stage size reduction grinder (210), then to 1/8
inch to 3/8 inch size particles in second stage size reduction
grinder (220) before entering third stage size reduction grinder
230. Both first second stage reduction grinder (210) and second
stage reduction grinder (220) can be operated while the feedstock
remains dry. In contrast, twice-reduced feedstock (221) is
preferably combined with liquid to form a slurry form when it
enters third stage grinder (230) and fourth stage safety grinder
(240).
[0040] A contemplated feedstock can include naturally occurring
biomass that contains one or both of lignin and polysaccharide
materials such as cellulose and hemicellulose polymers, as well as
chemically modified polysaccharides such as methyl cellulose,
cellulose acetate, rayon and the like (collectively referred to
herein as cellulosic material). These sources can further include
various biomass sources, including wood chips, sawdust, brush, hay,
straw, switch grass, corn stalks, kudzu and other sources of
cellulosic material such as paper and cardboard, and mixtures
thereof.
[0041] The sources of cellulosic material can be permitted to dry
or can be actively dried to a selected moisture content. Those
cellulosic material sources can also be blended to result in a
desired moisture content. If necessary, water can be added to
overly dry feedstocks. These sources of cellulosic material and
lignin can be blended with each other and with other polymer
feedstocks, or used as a single uniform type of cellulose.
[0042] The process can also utilize a synthetic polymer as the
feedstock carbon-containing polymeric material. The synthetic
polymer can be a hydrocarbon or other polymer. For example, waste
plastic such as polystyrene, polyester, polyacrylate, polyurethane,
polyethylene, polypropylene and rubber, such as is present in
vehicle tires can be utilized as a feedstock source. Mixtures of
synthetic polymers with cellulosic material are also acceptable for
use as the feedstock. Tires can include all of the polymers now
used to manufacture tires, such as butadienes and fillers, such as
carbon, silica, aluminum and zinc acetate.
[0043] A wide variety of synthetic carbon-containing synthetic
polymer or cellulosic polymer materials, including rubber, plastic,
trees, bushes, brush, bark, sawdust, wood chips, hay, straw, switch
grass, field stubble, paper, cardboard and the like can be used as
feedstock in accordance with the invention. However, certain
materials require additional attention. For instance, bark can be
used. However, because bark is high in ash and absorbs water
readily, when using bark as feedstock, special attention needs to
be paid to insure moisture content. Similarly, although pine saw
dust can be used, it is recommended to limit the weight of pine saw
dust used at less than 25% of the total feedstock weight.
[0044] The moisture content of the feedstock is of import to a
contemplated process. The moisture content of the feedstock can be
controlled and adjusted before or after the feedstock enters the
first stage size reduction grinder (210) or second stage size
reduction grinder (220). Feedstock of various moisture contents can
be blended to achieve desirable average moisture content. If
necessary, additional water can be sprayed or otherwise added into
the system. Feedstock such as grasses, brush and wood chips can be
permitted to dry before entering a process in accordance with the
invention. Regardless of when the feedstock is dried or moistened,
the average water content is preferably about 5 to about 25%, more
preferably about 15 to about 20% and most preferably about 16 to
about 17% by weight of the feedstock.
[0045] In accordance with embodiments of the invention shown in
FIG. 2, the third stage grinder (230) can be constructed and
arranged to receive output (221) from the second stage grinder
(220) and, in addition, two additional feeds, including a liquid
feed (270) and an initiator feed (280). All the inputs to third
stage grinder (230) are mixed to form a slurry (231) having the
above-identified water content.
[0046] The input from liquid feed (270) advantageously comprises a
non-aqueous hydrocarbon/oxyhydrocarbon solvent (271). In one
preferred embodiment of the invention, the
hydrocarbon/oxyhydrocarbon solvent can be final output (421) of
plant (10). However, it is not necessary to use a recycle of the
final product, and other hydrocarbon/oxyhydrocarbon solvents can be
used. Liquid feed (270) advantageously changes the viscosity of
slurry (231). The addition of hydrocarbon solvent (271) fills out
the available space in reactors discussed below to ensure an oxygen
free environment. The liquid phase also makes size reduction
easier.
[0047] A particularly useful and relatively low cost
hydrocarbon/oxyhydrocarbon solvent is No. 2 diesel fuel. No. 2
diesel fuel is typically petroleum-derived and is composed of about
75% saturated hydrocarbons (primarily paraffins including n, iso,
and cycloparaffins), and 25% aromatic hydrocarbons (including
naphthalenes and alkylbenzenes). The average chemical formula for a
molecule of common diesel fuel is C.sub.12H.sub.23. No. 2 diesel
fuel is a mixture of hydrocarbons that typically correspond to the
formula approximately C.sub.10H.sub.2O to C.sub.15H.sub.28. No. 2
diesel fuel typically has a boiling point of about 285.degree. to
about 340.degree. C. (at one atmosphere), a melting point of about
-30.degree. to about -18.degree., and a density of about 0.87 to
about 0.95 g/cm.sup.3. Characteristics of No. 2 diesel are
described in IPCS (International Programme on Chemical Safety)
document 1564, October 2004.
[0048] Synthetic diesel produced from the Fischer-Tropsch process
is also useful. Synthetic diesel can also be produced from natural
gas in the Gas-to-liquid (GTL) process or from coal in the
Coal-to-liquid (CTL) process. Such synthetic diesel has about 30%
less particulate emissions than conventional diesel. No. 2 fuel oil
and No. 2 diesel are substantially the same and have a flash point
of 52.degree. C.
[0049] This solvent phase should, however, while mostly comprising
organic solvent, contain controlled amounts of water. The water can
act as a source of hydrogen for aiding the reduction of molecular
size. Water content is preferably about 25% to about 5%, more
preferably about 15% to about 20%, and most preferably about 16% to
about 17% of the feedstock.
[0050] Initiator feed (280) introduces initiator/catalyst particles
(281) to the input of third stage grinder (230). Initiators can
include elements of Group IB, IIB, IIIA, IVA, VB, VIIB, VIIB and
Group VIII. Preferred initiators include Group IB (copper, silver
and gold), IIB (zinc, cadmium and mercury) and VIII (iron,
ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium,
platinum) metals. Exemplary preferred initiators include platinum,
iron, aluminum, aluminum silica, zinc and copper. An
initiator/catalyst comprised of particles of one or more Group VIII
metals is particularly preferred. The metal initiator/catalyst can
be provided as a metal powder with substantially all, but at least
80% of the particles having a diameter (or largest dimension) of
less than about 1000 microns (passes through a No. 18 Standard
Sieve), preferably less than about 500 microns (passes through a
No. 35 Standard Sieve), more preferably about 300 microns (passes
through a No. 50 Standard Sieve) or less.
[0051] The initiator can be provided as pure metal powders.
Alternatively, polymeric materials, such as used tires, can be used
to provide the metal initiator.
[0052] A preferred source of the metal catalyst comes from ground
up tires, e.g., tires used on an automobile, truck, aircraft,
construction equipment, military vehicle and the like. Conventional
automobile tires include steel belts. These belts are commonly
formed from iron-containing wire that is coated with copper, which
in turn, can be coated with zinc. A steel-belted tire typically
contains about 20 to about 25% by weight iron, and that amount can
be used in determining the amount of initiator/catalyst present at
the beginning of a reaction. The steel belts in tires contain iron
that can be coated with copper and/or zinc. The synthetic rubber
itself includes aluminum and silica materials. All the metals in
the tire can serve as initiators.
[0053] In a preferred embodiment of the invention, essentially all,
but at least 80% of the tires are ground into smaller pieces,
preferably in multiple stages, to a size less than about 1,000
microns, more preferably less than about 500 microns and most
preferably about 300 microns or less. This size reduction results
in the production of metal particles in the above sizes. The final
size reductions advantageously take place in a slurry.
[0054] The process described herein can use automobile, tractor and
truck tires or general plastic polymer waste as sources of plastic,
carbon, iron and copper. The plastic polymers of butadiene,
styrene/butadiene, Buna N, Neoprene, polyesters, polyurethanes and
others depending on the manufacturers polymer blend can be
depolymerized and serve as sources of carbon-containing polymer
radicals to form iso, secondary, and other polymers with the
intermediate unsaturated polymers formed from cellulose.
Halogen-containing polymers, sulfur-containing polymers and
nitrogen-containing polymers are preferably not used as part of the
feedstock. The polymeric materials of the feedstock are
substantially free of halogen, sulfur and nitrogen atoms and can
contain up to about 10 weight percent by weight of all of those
atoms when calculated together. Preferably, the total weight
percentage of all of the halogen, sulfur and nitrogen atoms in the
polymeric feedstock is less than about 5 percent. The metals can
react with the water and cellulose to remove oxygen and form in
situ hydrogen. The metal oxides can be removed from the process
slurry and sold as a by-product. Tires and plastics can be used as
100% of the raw material or some lesser percentage. The presence of
the tires and plastics reduce the amount of catalysts and carbon
needed for the process.
[0055] Initiator/catalyst (281) is added to the third stage grinder
(230). Regardless of the source of initiator (281), it should have
a particle size less than about 1000 microns, preferably less than
400 microns and more preferably about 300 microns or less. The
smaller size can lead to a more optimal reaction rate because of
the increased surface area. Initiator (281) should comprise more
than 1% by weight of feedstock (201), preferably more than 3% and
most preferably 5% or more preferably up to about 10%.
[0056] Once feedstock (201) has undergone size reduction, the
slurry output (231) is fed into slurry storage tank (250). The
slurry output (231) can then be utilized in a chemical reaction
process in reaction section (300).
[0057] Preferred embodiments of the invention comprise a reaction
section (300). Preferred processes can involve multiple reaction
stages in multiple reactors (2, 3, 4 or more) to break down
feedstock into short chain carbon radicals. Those radicals,
preferably 2- through 9-carbon chains, e.g., 2-, 3-, 4-, 5-, 6-,
7-, 8- and 9-carbon chains, repolymerize to form a liquid, burnable
synthetic fuel as a final output (421) of the plant (10). Such
fuels can be prepared to be identical to conventional vehicle fuels
refined from crude oil.
[0058] Referring to FIG. 3, the reaction section (300) preferably
comprises a first reactor (310), a second reactor (320) and a third
reactor (330) linked in series. Optional systems and methods can
involve fewer or more reactors. Each reactor is preferably in the
form of a horizontal tube. Preferred sizes are about 30 feet in
length with a 2.5 foot inside diameter (about 12:1
length:diameter). Lengths and diameters of the reactors vary
depending on plant production capacity. However, a length to
diameter ratio of about 5:1 to about 20:1 is acceptable with about
10:1 to 15:1 being preferred. An internal screw (auger) is used to
move the reactants in plug-flow, through the reactor at controlled
speeds. The screw is of a variable speed so that time of plug flow
through the reactor can be adjusted despite changes in flow volume
and reaction rates.
[0059] Electrical heating elements on the reactor surfaces
advantageously control the temperature inside the reactors,
permitting a gradual and uniform rise in temperature across the
length of the reactor, while minimizing fire hazard from an open
flame. Super heated steam and open flames can also be used to heat
the reactor. Viscosity is generally proportional to molecular size.
Thus, viscosity measurements are advantageously taken at the output
of each reactor and analyzed, in order to adjust the heating
elements and screw speed, to provide the optimal reaction time,
temperature and pressure. Temperature can be measured at the input,
output and at intermediate points. The viscosity measurements can
be used to affect the heating elements and screw speeds to adjust
residence times and reactor temperature as needed. The reactants
can spend between 10 to 15 minutes, preferably a residence time of
about 11 to 13 minutes in each reactor.
[0060] Each reactor should be sealed off from the atmosphere and
pressurized to ensure an anaerobic reaction with no added
atmospheric oxygen. However, the pressure in each reactor need not
be specifically controlled. Rather, pressure can be the result of
the increase in temperature. Because of the lack of oxygen and the
ability to control surface temperature of the reactors, there is
relatively negligible char build-up after reactions to require
extensive and frequent cleaning. In addition, the auger tends to
provide a constant cleaning function.
[0061] The goal of the first reactor (310) and second reactor (320)
is to liquefy and break down the feedstock polymers to short chain
molecules, including monomers and monomer radicals. In one
embodiment of the invention, to begin reaction, slurry output (241)
is heated to about 250.degree. F. (120.degree. C.) at a gauge
pressure of about 690 kPa (100 psig) and fed into first reactor
(310). The temperature increase can be achieved in various ways,
preferably by recycling hot liquid or slurry streams from other
parts of plant (10). While in the first reactor (310), the
temperature of the reactants continues to rise, resulting in a
liquefied output (311) with the temperature about 450-500.degree.
F. (230-260.degree. C.) at a gauge pressure of about 3,500 kPa (500
psig). During the residence time in the first reactor (310),
various solids of slurry output (241) are liquefied by the
reactions at increasing temperature and pressure. Speed and
temperature are preferably adjusted so that no more than a trace of
non-liquid material leaves the first reactor (310).
[0062] The second reactor (320) is constructed and set up in a
similar manner as the first reactor (310). Liquefied output (311)
from first reactor (310) enters second reactor (320) at a
temperature of about 450.degree. F. (230.degree. C.) and a gauge
pressure of about 3,500 kPa (500 psig). Generally, unlike the
endothermic reaction in first reactor (310), because the reaction
in second reactor (320) is typically exothermic, no additional heat
is typically needed except for the purpose of maintaining constant
temperature and controlling reaction rate.
[0063] It is believed that while in first reactor (310), as the
temperature increases from about 250.degree. F. (120.degree. C.) to
450.degree. F. (230-450.degree. C.), the metal initiator/catalyst
(281) begins to react with available water in the feedstock to
become oxidized by freeing hydrogen in water, creating free
hydrogen. The free hydrogen, along with high temperature and
pressure, liquefies solids in slurry output (241) by attacking the
bonds in hydrocarbon polymers and in cellulosic materials to make
shorter chain molecules and promote the liquefaction of the feed
stream. When carbon-carbon bonds are cleaved, more hydrogen is
produced. About 50-70% of the breakdown of plastic and cellulosic
materials to short chain molecules can occur in the first reactor
(310).
Reforming:
##STR00001##
[0065] Once liquefied output (311) enters the second reactor (320),
components are believed to continue to be broken down into short
molecular links and further into intermediates through the process
of dehydration on the surface of the particulate initiator (281).
The length of carbon chains can be altered and controlled by
changing the temperature, reactor residence time and amounts of
initiator (281) added.
[0066] The hydrogen created in the reactor (310) is believed to
react with intermediates to saturate double bonds to form alkyl
hydrocarbon radicals. These hydrocarbon radicals, preferably 2-,
3-, 4-, 5-, 6-, 7-, 8- and 9-carbon chains are believed to be
weakly bonded to the surface of initiator (281) with unsaturated
double bonds, readily available for polymerization while the oxygen
from the hydroxyl groups continues to oxidize initiator (281). Some
oxygen reacts with free hydrogen to form water. Some traces of
alcohols such as ethanol and methanol are also formed.
Dehydration:
##STR00002##
[0067] Hydrogenation:
##STR00003##
[0069] The series of reformation, dehydration and hydrogenation are
self-activating because of the derivative intermediates formed. As
long as the surface area of an initiator (281) plus the temperature
and pressure are maintained in an appropriate balance, the cycle of
reformation, dehydration and hydrogenation continue to replicate.
Furthermore, dehydration and hydrogenation are both self-sustaining
steps because they are exothermic reactions.
[0070] An output (321) of second reactor (320), typically
comprising short chain hydrocarbon radicals as well as
substantially oxidized initiator (281), exits second reactor (320)
at about 650.degree. F. (340.degree. C.) and a gauge pressure of
about 4800 kPa (700 psig) after a residence time of about 10-12
minutes in the second reactor (320). The exothermic effect of
dehydrogenation provides heat to be recycled to first reactor (310)
to raise the temperature of slurry output (241) from storage tank
(250).
[0071] Head-to-tail polymerization of short chain carbon radicals
is understood to begin automatically in the third reactor (330) as
temperature is raised up to about 700.degree. to about 800.degree.
F. At this point in the reaction, initiator (281) is thought to
have been converted to a sufficiently high oxidation state or fully
oxidized to become inactive as to attack bonds to create free
hydrogen as experienced in first reactor (310). However, oxidized
initiator particles continue to provide surface sites for the
polymerization of the short chain hydrocarbon radicals into
hydrocarbons of selected lengths. The length of the carbon chain of
the reformed polymers can be controlled by adjusting the residence
time and temperature of third reactor (330). For example, to
produce gasoline, shorter molecules of 6-12 carbon atoms are best.
For diesel duel, 12-21 carbon molecules and for aircraft fuel,
15-19 carbon molecules are preferred. It is also preferred that at
least about 80% of the produced combustible fuel contain about 6 to
about 12 carbons per molecule, about 12 to about 21 carbons per
molecule or about 15 to about 19 carbons per molecule.
[0072] It is within the skill of the art to adjust time,
temperature and pressure in the three reactors to adjust the output
as desired. In any event, for diesel fuel, polymerization in the
about 700 to about 800.degree. F. (370-425.degree. C.) range;
gasoline, about 800 to about 850.degree. F. (425-455.degree. C.)
and kerosene, about 750 to about 850.degree. F. (400-455.degree.
C.) should be acceptable. The polymerization takes place at a
very-high temperature. Dropping the temperature lowers and stops
the rate of polymerization. Some copolymerization and branched
polymerization can also occur. This can be enhanced by recycling
the output. This leads to enhanced octane ratings.
[0073] When the desired polymerization has occurred, the content of
the third reactor (330), a polymerized output (331), is fed into a
flash column (420) shown more clearly as part of final section
(400) in FIG. 4. optionally, before the polymerized output (331)
enters the flash column (410), a shock wave device (410) is
employed to use shock waves to break up long chain polymers into
shorter chain polymers.
[0074] A shock wave device (410) operates at high temperatures and
sends sonic waves to break up long molecular chains. Acceptable
shock wave devices are available from Seepex, Inc. of Enon, Ohio.
In the present invention, a shock wave device (410) helps break up
any wax and other 25-30 carbon chain molecules into shorter chain
molecules.
[0075] As the pressurized polymerized output (331) enters the flash
column (420), the pressure is reduced from a gauge pressure of
about 5500 kPa (800 psig) to a gauge pressure of about 1380 kPa
(200 psig), while the temperature is lowered to about 400.degree.
F. (205.degree. C.). The decrease in temperature ends
polymerization. Within flash column (420), lighter carbon chains,
such as those with fewer than 12 carbons, are understood to
vaporize, and can be collected through a vent and can be condensed
through a condenser (430) as a fuel source such as gasoline. In the
production of diesel fuel, 6 to 8% of polymerized output (331) is
understood to vaporize in flash column (420). Traces of carbon
dioxide and carbon monoxide are also vented off at this time. They
can be collected or processed, if it is desired, to reduce
greenhouse emissions. Carbon chains with more than 12 carbons tend
to stay in liquid phase and can be collected as a final output fuel
(421). Final output fuel (421) can be recycled advantageously as
input to liquid feed (270), where it can serve as the required
non-aqueous hydrocarbon solvent.
[0076] Typically, the weight of final output fuel (421) recycled
and the weight of solid feedstock (201) input into size reduction
section (200) of plant (10) should have about a 1 to 1 to a 1 to 2
ratio. Recycled final output fuel (421) acts as a heat source and
provides initiators 281 to the feedstock stream.
[0077] The process described and claimed herein differs from the
known Fischer-Tropsch process in certain key: respects. The
Fischer-Tropsch process starts with the combustion of a
carbon-based organic compound in the presence of a supply of oxygen
insufficient for a complete reaction, such that the combustion
reaction produces principally carbon dioxide, carbon monoxide and
hydrogen according to the general reaction:
C.sub.NH.sub.2N+.sub.XO.sub.X+O.sub.2 cat
CO.sub.2+CO+H.sub.2+H.sub.2O
The ratio of combustion products in that process is varied with
operating conditions, catalyst and pressure. The carbon monoxide
(CO) and hydrogen are then purified and reacted further over
different catalysts to produce a variety of carbon chain length
hydrocarbons and alcohols. Some ethers and acids may also be
formed. The Fischer-Tropsch process is a gas phase chemistry
process.
[0078] The process of the present invention is preferably carried
out in liquid anaerobic conditions where no free oxygen or air is
permitted except the naturally entrained air in the raw organic
materials. The process can be carried out in organic liquid form
and no combustion is permitted to occur. The three-stage reaction
involves converting the controlled moisture in the raw materials to
a catalyst oxide and free hydrogen. In the second stage of a mode
of practicing the process the catalysts react with the oxygen in
water, the cellulose and plastics to form a catalyst oxide and
unsaturated carbon chains, which react with the in situ free
hydrogen to form, saturated multiple carbon chain radicals. In the
third stage of a mode of practicing the process, the carbon chain
radicals are reacted and polymerized to form iso, secondary and
normal chains of controlled molecular weight. The three-step
process can be carried out in continuous mode with different
operating conditions for each step.
[0079] In a preferred embodiment, a ferrous metal separator (430)
and a nonferrous metal separator (440) are utilized to remove and
recycle initiators (281). Ferrous metal separator (430) can be
assembled as a magnetic system that captures any iron or iron
oxides in final output (421). The collected iron particles can be
reduced back to their metallic form to be reused in the invention
again, or sold as scrap. Non-ferrous metal separator (440) is a
pressure filter type separator. Once separated, these non-ferrous
metal particles can be washed and sold to the fertilizer
industry.
[0080] Preferred embodiments of the invention are illustrated with
reference to the following examples, which are presented by way of
illustration only and should not be construed as limiting.
Example I
TABLE-US-00001 [0081] Feedstock 75 g (30% wood, 30% hay, 15% switch
grass, 25% styrene/butadiene polymeric plastic) Feedstock particle
size <300 microns Moisture content 15% Initiator 25 g of iron
(Fe) Initiator particle size <300 microns Solvent 75 g of a
mixture of organic liquids (alkanes of carbon number C5 to C2l)
Reaction temperature 700-800.degree. F. (370-425.degree. C.)
Reaction duration 3-20 minutes Product: 95% C3 to C21 molecules, 5%
carbon number 58.25 g greater than 21
Example II
TABLE-US-00002 [0082] Feedstock 100 g of pure wood cellulose
Feedstock particle size 500 microns or less Moisture content 20%
Imitator 10 g of copper (Cu) and 10 g of zinc (Zn) Initiator
particle size <200 microns Solvent 100 g of diesel fuel Reaction
temperature 600.degree. F. (315.degree. C.) Reaction duration 10
minutes Product: 93% C6 to C12 alkanes and alkanols, 7% C12 50.22 g
to C21 alkanes and alkanols
Example III
TABLE-US-00003 [0083] Feedstock 100 g of hay Feedstock particle
size <100 microns Moisture content 7% Imitator 5 g of platinum
(Pt) Initiator particle size <100 microns Solvent 100 g of
combined liquid products of Example I and Example II Reaction
temperature 850.degree. F. (455.degree. C.) Reaction duration 15
minutes Product: 94% C6 to C12 alkanes and alkanols, 6% C12 to
56.58 g C18 alkanes and alkanols
[0084] The above examples show the variety of feedstocks that can
be used in the system to produce different synthetic fuels in
accordance with the invention. The type of synthetic fuel produced
can be controlled by the type of initiator used as well as reaction
conditions such as those within third reactor (330). It is
understood that in first reactor (310) and second reactor (320),
the feedstock is substantially liquefied by breaking intermolecular
and intramolecular bonds using increased temperature and the
reaction between the water and metal catalyst initiators. Feedstock
is broken into short chain hydrocarbon moieties, ready to combine
with others and polymerize. In the third reactor (330), the
radicals automatically polymerize as the temperature and pressure
are increased to optimize the reaction rate. At this point,
initiators that played a significant role in creating hydrogen that
attacks and breaks bonds have transformed from highly active
chemical initiators to highly oxidized and therefore active surface
catalysts that provide surface sites for polymerization. The
initiators serve different purposes in the reformation,
dehydration, rehydrogenation and polymerization reactions in the
various reactors as their oxidation state alters with the
reaction.
[0085] Table 1A, below, provides a summary of product that has been
produced using a blend of tire chips, wood chips and straws after
running the entire system for 24 hours. Runs 1 to 7 used iron and
initiator/catalysts from tires (such as, for example, copper, zinc,
silica, aluminum) to initiate and further reactions, with a
feedstock comprised of about 25% tires, 50% grasses and straw and
about 25% green wood chips, so that there was about 5-6% iron as
initiator present. Instead of using tires as a source of initiators
and of carbon-containing polymer, runs 8, 9 and 10 of Table 1B used
about 6% by weight pure metal powder comprising 90% iron and 10%
copper with a feedstock comprised of about 50% grass and straw
(grass/straw) along with about 50% by weight green wood chips. Runs
11 to 13, also used metal powder at the ratio of 90% iron, 5%
silica and 5% aluminum with the grass/straw and wood chips
feedstock. The reaction times are listed, as well as temperature
and pressure during reaction.
TABLE-US-00004 TABLE 1A Run Number 1 2 3 4 5 6 7 Reaction time 12
12 12 12 12 8 13 (minutes) Reaction 260 315 370 400 425 425 315
temperature (500) (600) (700) (750) (800) (800) (600) .degree. C.
(.degree. F.) Reaction 20 25 30 40 50 50 30 pressure (atm) Carbon
number Product Analysis C1 -- <.5 1 1 2 -- -- C2 -- <.5 3 4 4
-- -- C3 -- -- 3 3 4 1 -- C4 2 3 3 3 3 3 -- C5 -- <1 <1 1 3 1
3 C6 2 3 5 5 8 -- -- C8 2 2 2 26 20 2 9 C10 4 6 18 25 21 -- -- C12
39 61 52 20 33 35 27 C14 10 17 9 6 -- 5 11 C16 13 1 2 2 1 17 10 C18
18 1 -- 1 1 19 26 C20 5 <1 1 1 -- 9 21 C22 4 3 -- 1 -- 9 1 C24 1
-- -- 1 -- 4 --
TABLE-US-00005 TABLE 1B Run Number 8 9 10 11 12 13 Reaction time 8
10 12 6 8 10 (minutes) Reaction 260 400 455 260 400 455 temperature
(500) (750) (850) (500) (700) (850) .degree. C. (.degree. F.)
Reaction 40 45 50 30 40 50 pressure (atm Carbon number Product
Analysis C1 -- -- 1 -- Trace 4 C2 -- -- 1 -- Trace 4 C3 -- -- 2 --
4 3 C4 <1 1 2 -- 4 4 C5 <1 1 9 2 3 6 C6 1 2 20 2 3 11 C8 1 2
23 1 13 26 C10 3 1 31 1 11 23 C12 13 14 6 24 19 13 C14 21 21 2 12
17 3 C16 24 21 1 12 18 1 C18 14 14 1 32 9 <1 C20 10 14 -- 10 4
<1 C22 10 8 -- 3 1 -- C24 1 1 1 1 4 --
[0086] Each of the patents and articles cited herein is
incorporated by reference. The use of the article "a" or "an" is
intended to include one or more.
[0087] The foregoing description and the examples are intended as
illustrative and are not to be taken as limiting. It is to be
understood that ingredients or compounds recited in the singular
are intended to include compatible mixtures of such ingredients
wherever the sense permits. Still other variations within the
spirit and scope of this invention are possible and will readily
present themselves to those skilled in the art.
* * * * *