United States Patent Application: 0130079577
As seen, for just several examples, in our reports of:
West Virginia Coal Association | Penn State Solar CO2 + H2O = Methane | Research & Development; concerning: "High-Rate Solar Photocatalytic Conversion of CO2 and Water Vapor to Hydrocarbon Fuels; The Pennsylvania State University; 2009; Efficient solar conversion of carbon dioxide and water vapor to methane and other hydrocarbons is achieved ... . All experiments are conducted in outdoor sunlight at University Park, PA"; and:
West Virginia Coal Association | Japan Solar Energy Converts More CO2 into Methane | Research & Development; concerning: "US Patent Application 20120234691 - Method for Reducing Carbon Dioxide; 2012; Assignee: Panasonic Corporation; A method for reducing carbon dioxide ... wherein ... at least one compound selected from the group consisting of methane ... is produced. ... The method for reducing CO2 of the present disclosure can be applied to methods using a solar cell as an external power supply. The catalyst for reducing CO2 can be applied, by combination with a photocatalyst, to catalysts which can be used with solar "; and:.
West Virginia Coal Association | New York City CO2 to Methane via Artificial Photosynthesis | Research & Development; concerning: "US Patent Application 20120208903 - Conversion of Carbon Dioxide to Methane Using Visible Light;2012; Assignee: Research Foundation of City University of New York; Abstract: The invention relates to a method for converting carbon dioxide to methane. The method comprises energyexposing carbon dioxide adsorbed on a nanoporous silicate matrix to light in the presence of a source of carbon dioxide and a source of hydrogen for a time and under conditions sufficient to convert carbon dioxide to methane. ... A preferred source of hydrogen is water";
we can, using nothing but sunlight to drive the chemical reactions, convert plain old Water, H2O, and that valuable, freely-available natural resource, Carbon Dioxide, CO2, into Methane; i.e., a substitute natural gas we don't have to put our drinking water, and our health, at risk by drilling and fracking for.
And, herein, from our very own United States Department of Energy, we present even more confirmation of that, what should by now be accepted as straightforward, fact.
As seen in excerpts, with additional links and comment appended, from the initial link in this dispatch to:
"US Patent Application 20130079577 - Synthesis of Photocatalysts for Solar Fuel Generation
http://images3.freshpatents.com/pdf/US20130079577A1.pdf
Date: March 28, 2013
(Note: As we have several times reported, official US Government Patent and Trademark Office electronic links to early published versions of US Patent Applications, as is the initial link in this dispatch, often prove transient and unreliable. Further, the US Patent Application that is the subject of this dispatch is so recent that it has not yet been made web-accessible by the secondary patent publishing sites we most often rely on for backup. That said, "US Patent Application 20130079577" is, at the time we post this, accessible via both the primary link at the top of this dispatch and the secondary link embedded immediately above. Further, we have been able to access and download a full copy of the document itself, which we will forward to the West Virginia Coal Association via separate transmission. They will, we presume, make it available to anyone who might have trouble with access via the enclosed links.)
Inventor: Brian Ingram, et. al., IL and TN
Assignee: UChicago Argonne, LLC, Chicago
(Note: As we have previously reported, our US Government, in it's wisdom, has farmed out management of our critical United States National Energy Technology Laboratories to consortiums of educational institutions and business corporations.
In this case, operations of the famed Argonne National Laboratory have, as can be learned via:
About Argonne | Argonne National Laboratory; "Argonne National Laboratory ...is one of the U.S. Department of Energy's largest national laboratories for scientific and engineering research. (More than) 1,250 scientists and engineers aim to solve the nation's most important challenges in energy, the environment and national security. Argonne is managed by UChicago Argonne, LLC, for the U.S. Department of Energy's Office of Science"; and:
UChicago Argonne, LLC: About; "For six decades, the U.S. Department of Energy's (DOE's) Argonne National Laboratory has excelled in conducting scientific research in support of a secure future for the nation. From Argonne's inception, the University of Chicago has managed and operated the laboratory, a laboratory that has become a scientific leader for DOE and the country. Argonne is operated by UChicago Argonne, LLC together with team member Jacob's Engineering Group Inc.This partnership underscores the University's commitment to delivering world-class research through the safe and efficient management and operation of Argonne National Laboratory";
for a long time been managed, for the USDOE and it's precedent agencies, by the highly-regarded University of Chicago, in partnership with at least one major and accomplished technical engineering firm.)
Abstract: In one preferred embodiment, a photocatalyst for conversion of carbon dioxide and water to a hydrocarbon and oxygen comprises at least one nanoparticulate metal or metal oxide material that is substantially free of a carbon coating, prepared by heating a metal-containing precursor compound in a sealed reactor under a pressure autogenically generated by dissociation of the precursor material in the sealed reactor at a temperature of at least about 600 C to form a nanoparticulate carbon-coated metal or metal oxide material, and subsequently substantially removing the carbon coating. The precursor material comprises a solid, solvent-free salt comprising a metal ion and at least one thermally decomposable carbon- and oxygen-containing counter-ion, and the metal of the salt is selected from the group consisting of Manganese, Titanium, Tin, Vanadium, Iron, Zinc, Zirconium, Molybdenum, Niobium, Tungsten, Europium, Lanthanum, Cerium, Indium, and Silicon.
(We have options, it seems, when it comes to the selection of a catalyst. And, we wouldn't have to rely on anyone, other than maybe our good friends in Canada, for the supply of any of those specified.)
Government Interests: The United States Government has rights in this invention pursuant to Contract No. DE-AC02-06CH11357 between the United States Government and UChicago Argonne, LLC representing Argonne National Laboratory.
Claims: A photocatalyst for conversion of carbon dioxide and water into a hydrocarbon and oxygen, the photocatalyst comprising at least one nanoparticulate metal or metal oxide material that is substantially free of a carbon coating, prepared by heating a metal-containing precursor compound in a sealed reactor under a pressure autogenically generated by dissociation of the precursor material in the sealed reactor at a temperature of at least about 400 C to form a nanoparticulate carbon-coated metal or metal oxide material, and subsequently substantially removing the carbon coating; wherein the precursor material comprises a solid, solvent-free salt comprising a metal ion and at least one thermally decomposable carbon- and oxygen-containing counter-ion; and wherein the metal component of the metal-containing precursor material is selected from the group consisting of Mn, Ti, Sn, V, Fe, Zn, Zr, Mo, Nb, W, Eu, La, Ce, In, and Si.
(The "pressure autogenically generated" just means that, like a pressure cooker on your stove, when heat is applied, for the "dissociation of the precursor material in the sealed reactor", the pressure inside the "sealed" vessel builds up, through, presumably, the "dissociation of the precursor". We don't, in other words, have to devise a separate means to apply the pressure.)
The photocatalyst ... wherein the metal oxide is selected from the group consisting of Mn3O4, TiO2, SnO2, V2O3, V2O5, Fe3O4, Fe2O3, ZnO, ZrO2, MoO2, MoO3, Nb2O3, Eu2O3, La2O3, CeO2, La2O3, SiO2, and a tungsten oxide; and optionally contains one or more promoters selected from noble metals and transition metals (and) wherein the counter-ion is selected from the group consisting of an organic ion, an inorganic ion, and a combination thereof.
The photocatalyst ... wherein the precursor material is selected from a titanium salt, a tin salt, a cerium salt, a zinc salt, an iron salt, and a combination of two or more of the foregoing salts (and) wherein the metal oxide comprises anatase TiO2, rutile SnO2, or a combination thereof.
(The above "anatase" and "rutile" just specify the crystalline structures of the Titanium and Tin oxides desired for use in this process. They're quite common and the terminology used is meaningful to mineralogists and chemically-minded geologists. They aren't rare or expensive gemstones; nor are they things that have to be synthesized, although they can be.)
The photocatalyst ... wherein the metal oxide comprises anatase TiO2 substantially free of a carbon coating, formed by thermal reaction of titanium acetoacetonate in a sealed reactor at a temperature of about 700 C under an autogenically generated pressure of up to about 150 pounds-per square-inch (psi) to form a nanoparticulate carbon-coated anatase TiO2 powder, and subsequently substantially removing the carbon coating.
The photocatalyst ... wherein the anatase TiO2 powder comprises particles having a particle size in the range of about 10 to about 30 nanometers.
The photocatalyst ... wherein the metal oxide comprises rutile SnO2 substantially free of a carbon coating, formed by thermal reaction of tin ethoxide in a sealed reactor at a temperature of about 600 C under an autogenically generated pressure of up to about 100 pounds-per square-inch (psi) to form a nanoparticulate carbon-coated rutile SnO2 powder, and subsequently substantially removing the carbon coating (and) wherein the rutile SnO2 powder comprises particles ... of about 10 to about 20 nm.
(Pretty small particles are required, but, such "powder" would likely be formed almost automatically by the thermal decomposition of the starting compound to form the semi-synthetic "rutile" and "anatase".)
The photocatalyst ... wherein the metal oxide comprises a mixture of anatase TiO2 and rutile SnO2 (and/or)CeO2 (and/or) ZnO (and/or) Fe3O4.
A method of converting carbon dioxide and water into a hydrocarbon and oxygen comprising exposing a gaseous mixture of carbon dioxide and water to sun light in the presence of a photocatalyst of at a temperature sufficient to catalyze reduction of carbon dioxide to a hydrocarbon, wherein the photocatalyst comprises at least one nanoparticulate metal or metal oxide material that is substantially free of a carbon coating, the metal or metal oxide material is prepared by heating a metal-containing precursor compound in a sealed reactor under a pressure autogenically generated by dissociation of the precursor material in the sealed reactor at a temperature of at least about 400 C to form a nanoparticulate carbon-coated metal or metal oxide material, and subsequently substantially removing the carbon coating; wherein the precursor material comprises a solid, solvent-free salt comprising a metal ion and at least one thermally decomposable carbon- and oxygen-containing counter-ion, and the metal of the salt is selected from the group consisting of Mn, Ti, Sn, V, Fe, Zn, Zr, Mo, Nb, W, Eu, La, Ce, In, and Si (and) wherein the metal oxide is selected from the group consisting of Mn3O4, TiO2, SnO2, V2O3, V2O5, Fe3O4, Fe2O3, ZnO, ZrO2, MoO2, MoO3, Nb2O3, Eu2O3, La2O3, CeO2, La2O3, SiO2, and a tungsten oxide; and optionally contains one or more promoters selected from noble metals and transition metals.
(There are, in other words, a lot of options, which affords opportunities for economy and security.)
Background and Field: This invention relates to the energy efficient photocatalytic conversion of carbon dioxide gas and water vapor to methane and other hydrocarbon fuels, particularly promoted by sunlight (referred to herein as "solar-derived fuel" or "solar fuel"). In particular, the invention relates to wide band-gap photocatalytic materials, as well as the synthesis and surface modification thereof, as materials for promoting solar fuel production.
As developing countries begin to prosper, fossil fuels will continue to be the primary source of the world's energy. Large deposits of coal throughout the world and the United States are relatively inexpensive and geopolitically stable.
Carbon dioxide, which is formed in the conversion of stored chemical energy in fossil fuels to electrical energy, is generally accepted to be a "greenhouse" gas and ... efficient capture and/or conversion of carbon dioxide is therefore an important technical challenge. Carbon dioxide is an extremely stable compound at standard conditions, and a large amount of energy is required to reduce it.
Titanium dioxide is a large band-gap semiconductor, which absorbs ultraviolet radiation to form an electron-hole pair. The solar-generated charge carrier can be transferred to adsorbed surface molecules, such as water or carbon dioxide, to promote oxidation and reduction reactions, for example reduction of carbon dioxide to methane or other hydrocarbons (e.g., ethane). To date, the photocatalytic reduction of carbon dioxide is highly inefficient due to limitations in the solar spectrum absorption, electron-hole recombination events, and charge transfer of uncombined electron-hole pairs to adsorbed molecular species on the titanium oxide surface.
In recent years, effort has been made to improve the efficiency of photocatalytic reduction of carbon dioxide (also referred to herein as "solar fuel conversion"). Cocatalyst structures consisting of a combination of metal oxide semiconductors and noble metals, and highly doped metal oxide semiconductors have been proposed in order to "tune" the adsorption edge (i.e., bulk band gap) of the photocatalysts. These approaches reportedly have increased the conversion efficiency to some degree; however, inefficient conversion has remained a significant impediment to widespread commercialization of this technology.
Consequently, there is an ongoing need for improved catalysts for photochemical (particularly solar) reduction of carbon dioxide to hydrocarbon fuels such as methane. The present invention addresses this ongoing need.
Summary: The present invention provides wide band-gap photocatalytic materials useful for catalyzing the solar conversion of carbon dioxide and water to hydrocarbons (particularly methane) and oxygen. The materials of the invention are prepared by reaction of one or more dry, solvent-free chemical precursor powders in a sealed reactor at elevated temperature and autogenically generated high pressure resulting dissociation of the precursor materials in the closed reactor at elevated temperature in a sealed reactor at high temperatures and high pressures generated autogenically by vaporization of precursor materials in the reactor.
(We'll interrupt to note, yet again, that the byproduct "oxygen" would have commercial value, which could help to offset the costs of such "solar fuel conversion". One possible use for Oxygen could be that disclosed in our report of:
West Virginia Coal Association | Conoco 2011 Coal + CO2 + H2O + O2 = Syngas | Research & Development; concerning: "United States Patent 7,959,829 - Gasification System and Process; 2011; Assignee: ConocoPhillips Company; A process for gasification of a carbonaceous material, comprising the steps of: a. introducing a dry feedstock comprising recycled char and a solid stream comprising particulate carbonaceous material into a reactor lower section and partially combusting therein with a gas stream comprising an oxygen supply selected from a group consisting of oxygen-containing gas, steam, and mixtures thereof, thereby evolving heat and forming products comprising synthesis gas and molten slag; (and) wherein said carrier liquid is selected from group consisting of water, liquid Carbon Dioxide, (or) mixtures thereof";
wherein it could be used to support the partial oxidation of Coal, and thereby supply the energy needed to convert Coal, Steam and Carbon Dioxide into a synthesis gas suitable for catalytic condensation into various hydrocarbons.)
In (one) preferred embodiment, the metal oxide comprises a mixture of anatase TiO2 and rutile SnO2 (e.g., about 95:5 to about 50:50 wt/wt TiO2:SnO2, for example about 95 percent by weight (wt %) of the TiO2 and about 5 wt % of the SnO2); or the metal oxide comprises CeO2, ZnO or Fe3O4.
In another aspect, the present invention provides a method of converting carbon dioxide into a hydrocarbons such as methane, ethane and the like comprising exposing a gaseous mixture of carbon dioxide and water to sun light in the presence of a photocatalyst of at a temperature sufficient to catalyze reduction of carbon dioxide to methane."
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Make no mistake: some appreciable amount of energy, in the form of heat, is required to accomplish, first, the synthesis of the photocatalyst disclosed herein; and, then, to use that photocatalyst in the process that, while using Solar light energy as the primary driver, converts Carbon Dioxide and Water into Oxygen and Methane.
However, as in our concluding excerpted paragraph, the "temperature sufficient to catalyze reduction of carbon dioxide to methane" in a reaction stimulated and promoted primarily by light, isn't really specified in the text of the full Disclosure. It is, though, discernible in charts and graphs included as foreword documentation with the full Application, which will, as noted, be transmitted to the West Virginia Coal Association.
Note that the temperatures provided and specified in the text of the Disclosure, i.e., as in "a temperature of at least about 400 C to form a nanoparticulate carbon-coated metal or metal oxide material", concern only the temperatures required to manufacture the photocatalyst, which is actually the invention disclosed in this United States Patent Application.
It is, we think, significant to note in passing that the process of converting Carbon Dioxide into Methane is not, herein, an invention. The fact that CO2 and H2O can be converted into Methane, with sunlight as the primary source of energy to drive the process, is treated as already-established fact.
But, the needed temperature for the Carbon Dioxide reduction reaction, to form Methane, is related to a certain extent to the intensity and type, i.e. wavelength, of light available to help drive the process, and, to the pressure maintained for the reaction, which pressure can be automatically generated by the elevated temperature and resulting chemical reactions within the contained reaction vessel.
Further, the reduction of CO2 to Methane proceeds over a wide range of processing conditions; but, at rates and percentages that vary with those conditions. The highest rates of conversion, according to the USDOE documentation included with the full patent application, are achieved at temperatures around twice the standard condition boiling point, 100 C, of water, i.e., at 200 C.
Again, that information is provided graphically in foreword documentation.
We note that, as demonstrated in experimental data provided by the USDOE in appended documentation, it is also possible to used artificial light to drive the CO2-to-Methane reduction/synthesis reaction; and, that certain wavelengths of light are more effective. The full solar spectrum isn't needed.
In any case, our review of available literature made available by the USDOE's Energy Citations Database clearly confirms, that, just as seen, for a few examples, in:
West Virginia Coal Association | USDOE Hydrogasifies Coal with Solar Power | Research & Development; concerning: "United States Patent 4,415,339 - Solar Coal Gasification Reactor; 1983; Assignee: The USA, as represented by the Department of Energy"; and:
West Virginia Coal Association | NASA Hydrogasifies Coal with Solar Power | Research & Development' concerning: "United States Patent 4,290,779 - Solar Heated Fluidized Bed Gasification System; 1981; Assignee: Administrator of the National Aeronautics and Space Administration";
Solar thermal energy can be collected and concentrated in sufficient amounts to drive endothermic Carbon conversion reactions of various sorts; and, as we will likely document via separate, future dispatch, can as well provide the heat needed to synthesize the catalyst of our subject herein, "United States Patent Application 20130079577 - Synthesis of Photocatalysts for Solar Fuel Generation".
The downside is that such Solar-powered Carbon conversion technologies would likely only succeed in the desert southwest and most southeastern portions of the United States; although, again, as seen in our already-cited report of:
West Virginia Coal Association | Penn State Recycles via Artificial Photosynthesis | Research & Development; concerning: "High-Rate Solar Photocatalytic Conversion of CO2 and Water Vapor to Hydrocarbon Fuels; The Pennsylvania State University; 2008; Abstract: Efficient solar conversion of carbon dioxide and water vapor to methane and other hydrocarbons is achieved using nitrogen-doped titania nanotube arrays, with a wall thickness low enough to facilitate effective carrier transfer to the adsorbing species, surface-loaded with nanodimensional islands of cocatalysts platinum and/or copper. All experiments are conducted in outdoor sunlight at University Park, PA";
other, related, Solar-powered processes for converting CO2 into Methane seem to work just fine in the cooler and often-cloudy outposts of US Coal Country.
But, either way, it's all okay by us, since any Methane generated by the process of our subject from Carbon Dioxide in, say, Florida, might help us to defeat Cap and Trade Carbon taxes in West Virginia.
And, we remind you, that, as seen for only one example in:
West Virginia Coal Association | More Exxon CO2 + CH4 + H2O = Hydrocarbon Syngas | Research & Development; concerning: "United States Patent 5,985,178 - Low Hydrogen Syngas using CO2 and a Nickel Catalyst; 1999; Assignee: Exxon Research and Engineering; Abstract: A process for making a synthesis gas comprising H2 and CO in the presence of a (specified) reforming catalyst ...from a feed including ... preferably methane ..., O2, H2O and CO2 ... . Synthesis gas having H2 to CO mole ratios less than 2:1 and even less than 1.5:1 are easily achieved with net CO2 consumption, which also makes the process environmentally beneficial. Synthesis gas (syngas) ... is used for various purposes, including synthesis of hydrocarbons and oxygenates (i.e., alcohols)";
once we have the Methane, as synthesized herein, via the process of our subject,"US Patent Application 20130079577 - Synthesis of Photocatalysts for Solar Fuel Generation", by our own US Department of Energy and it's contractors, from Carbon Dioxide, we can then, according as immediately above to Exxon, react that CO2-based Methane with even more Carbon Dioxide, as recovered from whatever convenient source, with both of them being converted through such reactions into "synthesis gas comprising H2 and CO", which "synthesis gas" is suitable for the subsequent "synthesis of hydrocarbons"; and, which CO2-based "hydrocarbons" might help us all to defeat foreign OPEC oil extortions throughout the entire United States of America.