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California Efficient CO2 to Methanol Photoelectric Conversion

United States Patent: 4521499

We submit herein two United States Patents for technologies, or, actually, for photoelectric processors and chemical processing systems, that are so closely-related that we are led to think of them as being "integrated".

And, the true intent of these inventions, and their associated processes, are buried so deep within, so close to the end of, the "Detailed Description"s sections of the full Disclosures that we are compelled to present an advance, edited excerpt, as follows:

"Photoelectrosynthetic cells employing the photoelectrode of the invention may convert essentially any organic reactant in the presence of water to an oxidized organic product and hydrogen. (Examples) of typical photoelectrosynthetic conversion reaction employing the photoelectrode of the invention include hydrogen chloride converted to hydrogen and chlorine, ... and water and carbon dioxide converted to methanol and oxygen."

By way of further introduction, there is nothing really new about the concept of electrochemically converting a solution of Carbon Dioxide in Water, as above, "to methanol".

As seen in:

USDOE 1976 Atmospheric CO2 to Methanol | Research & Development; concerning: "United States Patent 3,959,094 - Electrolytic Synthesis of Methanol from CO2; 1976; Assignee: The USA as represented by the USDOE; Abstract: A method and system for synthesizing methanol from the CO2 in air using electric power.The CO2 is absorbed by a solution of KOH to form K2CO3 which is electrolyzed to produce methanol, a liquid hydrocarbon fuel";

our own United States Government has known how to do it, has owned the rights to do it, for well more than one quarter of a century.

Further, as seen in:

Japan Converts CO2 to Methanol | Research & Development; concerning: "US Patent 7,488,404 - Process for Hydrogenating Carbon Dioxide; 2009; Inventor: Masayoshi Matsui (Japan); Abstract: A process for hydrogenating carbon dioxide to generate methanol (wherein hydrogen) is generated (via catalyzed) electrochemical reactions (and) a large quantity of carbon dioxide can be rapidly processed without any special equipment (and) methanol can be mass-produced as a useful main product";

such electrochemical Carbon Dioxide utilization techniques have grown more efficient and productive.

And, as seen in:

Texaco Photosynthetic CO2 Recycling | Research & Development; concerning:"United States Patent 4,545,872 - Method for Reducing Carbon Dioxide to Provide a Product; 1985; Assignee: Texaco, Incorporated; Abstract: A process and apparatus for reducing carbon dioxide to at least one useful product includes two redox couple electrolyte solutions separated by a first membrane having photosensitizers. The carbon dioxide to be reduced is provided to a second membrane which is contiguous to one of the redox couple electrolyte solutions. The second membrane has photosensitizers and a catalyst. Water provides hydrogen ions, which participate in the reduction of the carbon dioxide, via a separator. In operation both membranes are illuminated and produce excited photosensitizers which cause electron transfer from a first redox solution to a second redox solution and thence to the carbon dioxide in the second membrane thereby, in cooperation with the hydrogen ions, reducing at least some of the carbon dioxide at a surface of the second membrane to provide at least one product (including) methanol (and/or) methane";

the petroleum industry recognized those potentials for the photo-electro-chemical processing of Carbon Dioxide and Water to form Methanol, and Methane, and began to develop their own technologies for efficiently conducting such processes.

Herein, very nearly, and to us suspiciously, coincident with the Texaco developments noted via just the one example cited immediately above, we see that another petroleum company had devoted apparently considerable effort and skill into developing the processing equipment necessary to conduct such desirable transmutations, which would, among other things, allow us to harness freely-available environmental energy to effect the conversion of Carbon Dioxide and Water into, among other things, liquid hydrocarbon fuels.

Comment, and an additional link to another, related, United States Patent follow excerpts from the initial link in this dispatch to:

"United States Patent 4,521,499 - Photoelectrochemical Electrodes and Uses Thereof

Date: June, 1985

Inventor: Jay Switzer, CA

Assignee: Union Oil Company of California, Los Angeles

(We are compelled to interrupt here to note, that, in 2005, the "Union Oil Company of California", "Unocal", was assimilated by Chevron, which had already, in 2001, gobbled up Texaco, and their rights to the "United States Patent 4,545,872 - Method for Reducing Carbon Dioxide to Provide a Product", cited above.)

Abstract: A photoelectrode, containing a highly conductive coating material having a band gap (as specified)on a substrate containing a semiconductor material, is utilized in photovoltaic cells, photoelectrosynthesis and photoelectrocatalysis.

Claims: A photoelectrode having (a specified coating material, and) wherein said coating material is catalytic ... on a substrate containing a semiconductor.

(The "Claims" go on at great, highly-detailed length to describe both the "photoelectrode" and the "photoelectrochemical cell" in which the "photoelectrode" is to be used. The terminology employed involves a lot of "ohms" and "Angstrom units", which, though unintelligible to us Coal Country troglodytes, would be clearly understandable to the denizens of California's Silicon Valley.)

(A) process (for) producing electricity in (the described) photovoltaic cell (and for) producing chemical products ... in (the described) photoelectrosynthetic cell (and) wherein said chemical products comprise hydrogen gas (and) at least one organic material ... .

Background and Field: The invention relates to photoelectrochemical electrodes and, more particularly, to the utilization of photoelectrochemical electrodes for producing electricity from semiconductor liquid junction photovoltaic cells and for producing stored energy products from photoelectrosynthetic and photoelectrocatalytic cells.

(Note that the end purpose of all of this is to produce "stored energy products".)

Summary and Description: Briefly, the present invention is directed to a photoelectrode, its method of preparation and a process employing such an electrode for the conversion of energy, especially solar terrestrial energy, into other forms such as electricity or chemical products.

Photoelectrosynthetic cells employing the photoelectrode of the invention may convert essentially any organic reactant in the presence of water to an oxidized organic product and hydrogen. Other examples of typical photoelectrosynthetic conversion reactions employing the photoelectrode of the invention include hydrogen chloride converted to hydrogen and chlorine, hydrogen bromide converted to hydrogen and bromine, hydrogen iodide converted to hydrogen and iodine, water and propylene converted to propylene oxide and hydrogen, and water and carbon dioxide converted to methanol and oxygen."

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Please, believe us when we tell you that you do not want to study the full Disclosure. Ask your local high school Physics class whiz kid, who just won the state science fair, to read it and explain it to you.

The bottom line, though, is this:

Unocal, now Chevron, developed an efficient device, that, when exposed to sunlight, would convert a blend of Carbon Dioxide in Water, i.e., something like plain old drug store beverage fountain soda water, or the effluent from a power plant CO2 scrubber, into Methanol and Oxygen.

And, not content with that seemingly-intriguing achievement, they then went on to make the device even better and more efficient, as seen in:

"United States Patent: 4592807 - Making Highly Conductive Photoelectrochemical Electrodes

Date: June, 1986

Inventor: Jay Switzer, California

Assignee: Union Oil Company of California, Los Angeles

Abstract: A photoelectrode, containing a highly conductive coating material (and as otherwise specified) is utilized in photovoltaic cells, photoelectrosynthesis and photoelectrocatalysis.

Claims: A method for preparation of a photoelectrode (as detailed and specified).

Background and Field: The invention relates to photoelectrochemical electrodes and, more particularly, to the utilization of photoelectrochemical electrodes for producing electricity from semiconductor liquid junction photovoltaic cells and for producing stored energy product from photoelectrosynthetic and photoelectrocatalytic cells.

(It) is an object of the present invention to provide a photoelectrode that is highly stable, especially when utilized in photoelectrochemical cells. 

Another object of the invention is to provide a coating material for a semiconductor-containing photoelectrode that improves the efficiency of a photoelectrochemical cell. 

Yet another object still is to provide a method for producing a highly stable photoelectrode that may be employed in a photovoltaic, photoelectrosynthetic or photoelectrocatalytic cell. 

A further object of the invention is to provide a photoelectrochemical cell employing a novel photocatalytic electrode.

Summary: Briefly, the present invention is directed to a photoelectrode, its method of preparation and a process employing such an electrode for the conversion of energy, especially solar terrestrial energy, into other forms such as electricity or chemical products.

Photoelectrosynthetic cells employing the photoelectrode of the invention may convert essentially any organic reactant in the presence of water to an oxidized organic product and hydrogen. Other examples of typical photoelectrosynthetic conversion reaction employing the photoelectrode of the invention include hydrogen chloride converted to hydrogen and chlorine, hydrogen bromide converted to hydrogen and bromine, hydrogen iodide converted to hydrogen and iodine, water and propylene converted to propylene oxide and hydrogen,and water and carbon dioxide converted to methanol and oxygen."

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So, with Unocal's "photoelectrosynthetic or photoelectrocatalytic cell", we can expose "water and carbon dioxide" to "solar terrestrial energy", better known more simply as just "sunlight", and convert that "water and carbon dioxide" into "methanol and oxygen".

Their processes seem similar in many respects to others about which we've reported, as in:

Standard Oil Electrolyzes CO2 to Carbon Monoxide | Research & Development; concerning: "US Patent 4,668,349 - Electrocatalytic Reduction of CO2 by Square Planar Transition Metal Complexes; 1987; Assignee: The Standard Oil Company, Cleveland; Abstract: A process for the electrocatalytic reduction of carbon dioxide comprises immersing a transition metal complex with square planar geometry into an aqueous or nonaqueous solution which has been acidified to a (specified) hydrogen ion concentration ... , adding the carbon dioxide, applying an electrical potential of from about -0.8 volts to about -1.5 volts ... , and reducing the carbon dioxide to carbon monoxide";

wherein the efficiency, and the word "efficient" is used liberally by Unocal in the full disclosures of their inventions, of the electrolytic conversion of H2O and CO2 solutions into their more valuable constituents, i.e., "carbon monoxide", as above, is highly optimized.

And, they are similar to yet others, as seen in:

Pittsburgh USDOE Converts CO2 to Methane & Methanol | Research & Development; concerning the: "Visible Light Photoreduction of CO2; 2009; American Chemical Society; National Energy Technology Laboratory, USDOE, Pittsburgh, PA; Abstract: A series of ... Titanium Dioxide (catalysts) have been synthesized, characterized, and tested for the photocatalytic reduction of CO2 in the presence of H2O (into) CH4 (Methane), with CH3OH (Methanol, among the) secondary products";

wherein sunlight can be used to drive the electrochemical reactions.

And, finally, keep in mind, that, no matter where or how we get the "methanol", we can then, as seen for just one example in our earlier report of:

Mobil Oil Coal to Methanol to Gasoline | Research & Development; concerning: "United States Patent 4,447,310 - Production of Distillates through Methanol to Gasoline; 1984; Mobil Oil Corporation, NY;

Abstract: A process for producing a wide slate of fuel products from coal is provided by integrating a methanol-to-gasoline conversion process with coal liquefaction and coal gasification. The methanol (made from coal) is converted to gasoline by contact with a zeolite catalyst. Solvent for coal extraction is process derived from the upgraded distillate fraction or gasoline fraction of the methanol-to-gasoline conversion";

convert that Methanol, as made so efficiently by the old Union Oil Company of California, now Chevron, using solar energy to drive the needed reactions, via the processes of our subjects herein, "United States Patent 4,521,499" and "United States Patent 4,592,807, out of Water and Carbon Dioxide, into Gasoline.