Chemistry of hydrocarbon compounds – Production of hydrocarbon mixture from refuse or vegetation
Reexamination Certificate
1999-10-07
2001-01-30
Yildirim, Bekir L. (Department: 1764)
Chemistry of hydrocarbon compounds
Production of hydrocarbon mixture from refuse or vegetation
C585S242000
Reexamination Certificate
active
06180845
ABSTRACT:
This invention pertains to a method for transforming biomass, such as waste of biological origin, into useful products, particularly to a method for transforming biomass to petroleum-like hydrocarbon mixtures by reaction with water under supercritical or near-critical reaction conditions.
Above a fluid's so-called critical pressure and critical temperature, the distinction between liquid and gas phases vanishes, and instead one finds a single “supercritical” fluid phase with unique properties. The critical temperature for pure water is 374.2° C., and its critical pressure is 221 bar. Near-critical water has properties that are similar in many respects to those of supercritical water, but can be characterized by two phases: (1) a relatively dense, hot, vapor phase; and (2) a relatively less dense (~0.5-0.8 g/cc), hot fluid phase. Typical near-critical and supercritical aqueous phases have temperatures and pressures in the range from about 320° C. to about 500° C. (or higher) and greater than about 200 bar.
U.S. Pat. No. 5,516,952 discloses a process for breaking down natural, synthetic, vulcanized, and non-vulcanized rubbers by selective oxidation in supercritical or near critical water with an oxidant such as air, oxygen, or other oxidizing agent. Typical products were said to include alkanes, alkenes, dienes, aromatics, alcohols, carboxylic acids, aldehydes, and ketones, all preferably having from about 3 to about 8 carbon atoms, as well as carbon dioxide, water, and halide acids.
The current inventors' own U.S. Pat. No. 5,830,763 discloses a process for the preparation of organic and inorganic deuterium-tagged compounds by heating with deuterium oxide under supercritical conditions. See also T. Junk et al., “Synthesis of polydeuterated benzothiazoles via supercritical deuteration of anilines,”
J. Labelled Compounds and Radiopharmaceuticals
, vol. 39, pp. 625-630 (1997); and T. Junk et al., “Preparative supercritical deuterium exchange in arenes and heteroarenes,”
Tetrahedron Letters
, vol. 37, pp. 3445-3448 (1996); and T. Junk et al., “Hydrogen isotope exchange reactions involving C—H (D, T),”
Chem. Soc. Rev.
, vol. 26, pp. 401-406 (1997).
W. Catallo et al., “Sonochemical dechlorination of hazardous wastes in aqueous systems,”
Waste Management
, vol. 15, pp. 303-309 (1995) discloses the use of ultrasonic processes to dechlorinate certain organic compounds.
W. Catallo, “Hydrocarbon Transformation in High Energy Aqueous Systems,” copies of slides presented at 25th Annual Conference of the Federation of Analytical Chemistry and Spectroscopy Societies (Oct. 11-15, 1998, Austin, Tex.) discusses some material from an early phase of the work disclosed in the present specification.
W. Catallo, “Hydrocarbon Transformation in High Energy Aqueous Systems: Analytical and Mechanistic Challenges,” Final Book of Abstracts, 25th Annual Conference of the Federation of Analytical Chemistry and Spectroscopy Societies (Oct. 11-15, 1998, Austin, Tex.) gave only the title of that presentation.
B. Didyk et al., “Hydrothermal oil of Guaymas Basin and implications for petroleum formation mechanisms,”
Nature
, vol.342, pp. 65-69 (1989) discloses that petroleum-like hydrocarbons had been found in association with certain submarine hydrothermal vent emissions in the Gulf of California, and that those hydrocarbons had a carbon-14 date of 4200-4900 years. The authors stated that the oil expulsion and migration mechanisms were provided by the hydrothermal fluids under pressures of 200 bar and temperatures up to and exceeding 315° C. at some vent outlets; and speculated that there were probably near-critical conditions further down the sedimentary column. See also F. Goetz et al., “Aromatic hydrocarbon-degrading bacteria in the petroleum-rich sediments of the Guaymas Basin hydrothermal vent site: preference for aromatic carboxylic acids,”
Geomicrobiology J
., vol. 11, pp. 1-8 (1993).
E. Baker et al., “Characteristics of hydrothermal plumes from two vent fields on the Juan de Fuca Ridge, northeast Pacific Ocean,”
Earth
&
Planetary Sci. Lett
., vol. 85, pp. 59-73 (1987) discusses the physical characteristics of hydrothermal plumes on the Juan de Fuca Ridge.
We have discovered that reacting organic compounds in near-critical or supercritical aqueous phases can dramatically transform the organic compounds over short time periods (on the order of minutes to hours) into petroleum-like hydrocarbon mixtures. The reductive process is conducted in anaerobic or near-anaerobic conditions, essentially free of any strong oxidants. Optionally, strong reducing agents or other co-reactants may be added to tailor product distributions. The novel process works with a wide range of organic compounds and biomass sources, including cellulose, chitin, starches, lipids, proteins, lignin, and whole cells.
The starting materials used in this process can come from a wide variety of sources, many of which would otherwise be waste materials, including by-products of food manufacture and distribution (e.g., fryer oils; waste scraps; last-press edible oils such as canola and olive oils, food processing wastes, seafood industry wastes); by-products of paper and other wood industry manufacturing (e.g., cellulose and lignin by-products); yard waste such as leaves and grass clippings; rice hulls; bagasse; seaweed; milling waste; cotton waste; animal waste. Disposal of these wastes is currently expensive, and can create environmental problems. For example, food oils currently are typically disposed as high biological-oxygen-demand wastes in aerobic digesters or other treatment systems, such as ponds or lagoons. Aerobic digester disposal is expensive, and the carbon dioxide generated is not accompanied by the evolution of usable energy. Effluents from aerobic digesters can cause eutrophication and impaired ecological function in rivers and wetland systems.
The present invention allows the conversion of waste lipids (for example) into a hydrocarbon mixture similar to a sweet crude petroleum, containing (for example) volatile alkane and alkene gases (C
2
to C
10
) and liquid hydrocarbon mixtures. This conversion allows the generation of a burnable fuel, as well as the generation of feed streams for reforming and distillation. The environmental and other costs associated with traditional fossil fuel extraction are reduced.
It has been estimated that the world will have consumed most known and projected sources of available crude petroleum within the next 70-100 years. Some of the resulting shortfall could be mitigated economically by using the present process to produce petroleum-like products and related materials (e.g., lubricants) from materials that are otherwise considered waste products. To reduce environmental impact further, it is preferred (though not required) that the energy used to create the supercritical conditions be obtained from an environmentally-friendly source, such as collimated and focused solar energy, geothermal energy, or electrical energy produced by co-generation at an industrial plant.
Reactions in accordance with the present invention may be conducted in continuous, batch, or semi-batch mode. To date, we have used both batch and stop-flow reactors to transform biomass in near-critical (320-390° C., 200-420 bar) and supercritical water (400-500° C., 400-500 bar). The biomass starting materials that we have used in prototype experiments to date have includedd lipids, nucleic acids, starch, protein, algae, whole plant matter, cellulose, chitin, humic acid, and lignin. Other starting materials that could be used include biological laboratory wastes (cells, media, etc.), and modified mixtures such as synthetic oils, pharmaceutical and medical wastes, and naturally occurring organic mixtures such as peat, partially decayed leaf litter, kerogen, etc. Typical reaction times under near-critical and supercritical conditions were one to eight hours.
REFERENCES:
patent: 5516952 (1996-05-01), Lee et al.
patent: 5589599 (1996-12-01), McMullen et al.
patent: 5830763 (1998-11-01), Junk et al.
patent: 6084147 (
Catallo W. James
Junk Thomas
Board of Supervisors of Louisiana State University and Agricultu
Runnels John H.
Yildirim Bekir L.
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