http://cat.chem.chiba-u.jp/PDF/2012%20CoordChemRev.pdf?v=s5
Carbon Dioxide, as it arises in only a small way, relative to natural sources of emission, such as and especially the Earth's inexorable processes of planetary volcanism, from our economically essential use of Coal in the generation of truly abundant and affordable electric power, is a valuable raw material resource.
Over the past several years, we have rather regularly documented the fact that Japan, as embodied in several of her universities and corporations, has been developing the science and technology for recycling Carbon Dioxide, as might be recovered from whatever source - - perhaps as occurs naturally, sometimes in quite surprisingly high concentrations, as a component of Natural Gas as it is extracted from natural geologic reservoirs - - and synthesizing from Carbon Dioxide a variety of gaseous and liquid hydrocarbons.
Moreover, they seem collectively motivated in Japan to accomplish the conversion of Carbon Dioxide into hydrocarbons through the harnessing of environmental energy, most specifically sunlight, to drive the necessary catalytic chemical reactions.
A few of our reports, spanning now years, concerning those Japanese developments, have included:
West Virginia Coal Association | Japan Recycles CO2 to Methane | Research & Development; from back in February of 2010, concerning: "Chemical conversion of carbon dioxide by catalytic hydrogenation and room temperature photoelectrocatalysis; S. Ichikawa; Hitachi Ltd.; International Conference on Carbon Dioxide Removal; October, 1994; Kyoto; This report gives new results on the developments of a rhodium-manganese catalyst for high-conversion of CO2 to methane by contact catalytic process and a photoelectrocatalytic process to convert CO2 to useful chemicals"; and:
"Electrochemical conversion of carbon dioxide to methane; Satoshi Kaneco, et. al.; Mie University, 2002; The electrochemical reduction of CO2 on a Cu electrode was investigated in aqueous NaHCO3 solution, at low temperature. Methane and formic acid were obtained as the main products. ... The synthesis of methane by the electrochemical method might be of practical interest for fuel production and the storage of solar energy".
In passing, we feel obligated to note that such use of "solar energy" to drive the "synthesis of methane" from Carbon Dioxide and Water, or Water Vapor, is one that has, as seen for example in:
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; Oomman K. Varghese, et. al.; The Pennsylvania State University; 2009; Efficient solar conversion of carbon dioxide and water vapor to methane and other hydrocarbons is achieved using nitrogen-doped titania nanotube arrays";
wherein the "other hydrocarbons", produced from Carbon Dioxide, Water and Sunlight, might well include, as explained by our United States Department of Energy, in, for just one more example, our report of:
West Virginia Coal Association | USDOE "Green Freedom" CO2 Recycling | Research & Development; concerning: "Green Freedom (TM) - A Concept for Producing Carbon-Neutral Synthetic Fuels; 2007; Jeffrey Martin and William Kubic; Los Alamos National Laboratory (USDOE); We have developed a low-risk, transformational concept, called Green Freedom (TM), for large scale production of carbon-neutral, sulfur-free fuels and chemicals from air and water. Green Freedom (TM) utilizes carbon-neutral power to recover carbon dioxide from the atmosphere; split water into hydrogen; and, convert hydrogen and carbon dioxide into synthetic fuels and organic chemicals. Many useful organic chemicals can be produced ... (and we) have developed Green Freedom (TM) concepts for evaluation specifically for production of methanol and gasoline";
some needed liquid hydrocarbons; been under development by various educational institutions and government agencies in the United States of America, as well.
Japanese scientists have brought all of the above together much more recently in the dissertation we bring to you herein: an article in the pre-publication stage explaining various ways in which Solar energy can be harnessed - - ways we very loosely and somewhat inaccurately label as "Artificial Photosynthesis" in our headline, there is both more and less to it than that - - to effect the conversion of Carbon Dioxide and Water into both gaseous and, as we loosely define them to include alcohols, liquid hydrocarbons.
We do note that the article, while fully documenting the reality and feasibility of converting Carbon Dioxide and Water into hydrocarbons, does stipulate that further development of catalysts is needed in order to make the CO2 recycling processes disclosed herein genuinely economical; although, as we will document in reports to follow, a full suite of United States and International patents, concerning what we take to be Carbon Dioxide recycling and conversion catalysts and Carbon Dioxide reaction and processing reactor designs related to the technologies reported herein, has been applied for by these and other Japanese scientists.
Comment follows, and is inserted within, excerpts from the initial link in this dispatch to:
"Recent Advances in the Photocatalytic Conversion of Carbon Dioxide to Fuels with Water and/or Hydrogen Using Solar Energy
(This article was submitted for pre-publication review earlier this year, and has undergone a few revisions since. It has now been officially approved for publication, and it's actual date of publication will likely be in 2013. When that occurs, the initial link included above will in all probability become inactive; and, in light of that eventuality, a full file of the pre-print article has been downloaded and can be made available. Further, it is also accessible currently via:
Yasuo Izumi; Department of Chemistry, Graduate School of Science, Chiba University; Japan
Abstract: Photocatalytic reduction of carbon dioxide to fuels using solar energy is an attractive option for simultaneously capturing this major greenhouse gas and solving the shortage of sustainable energy. Efforts to demonstrate the photocatalytic reduction of CO2 are reviewed herein. Although the photocatalytic results
depended on the reaction conditions, such as the incident/absorbing light intensity from the sun or a simulated solar light source, the performance of different systems is compared. When the reactants included CO2 and water, it was necessary to determine whether the products were derived from CO2 and not from impurities that accumulated on/in the catalysts as a result of washing, calcination, or pretreatment in a moist environment. Isotope labeling of (Carbon 13)CO2 was effective for this evaluation ... . Comparisons are limited to reports in which the reaction route was verified spectroscopically, the C source was traced isotopically, or sufficient kinetic analyses were performed to verify the photocatalytic events. TiO2 photocatalytically produced methane (and, in) aqueous solutions, formic acid, formaldehyde, and methanol were also produced. When TiO2 was atomically dispersed in zeolites or ordered mesoporous Silicon Dioxide and doped with Platinum (and other specified metals and metal compounds) the methane and Carbon Monoxide formation rates were greater ... . (Specified catalysts) produced methane or methanol (while others preferentially) produced Carbon Monoxide ... . (In) addition to the historically known Zinc Oxide and Gallium Phosphide ((for) formaldehyde and methanol formation). The photocatalytic reduction of CO2 was also surveyed with hydrogen, because hydrogen can be obtained from water photosplitting by utilizing natural light.
(The "Carbon Monoxide" product might not sound too exciting; but, as in, for one example, our report of:
West Virginia Coal Association | Standard Oil Carbon Monoxide + Water = Gasoline | Research & Development; concerning: "United States Patent 4,559,363 - Process for Reacting Carbon Monoxide and Water; 1985; A process for reacting carbon monoxide and water in the presence of a cadmium-containing catalyst ... for the direct production of gasoline";
among others similar, Carbon Monoxide, unpleasantly poisonous though it might be, can be some useful stuff to have a little of, especially if we're making it in the first place out of Carbon Dioxide.
As far as the statement that any needed or desired "hydrogen can be obtained from water photosplitting by utilizing natural light", we refer you, again for only one example, to our report of:
West Virginia Coal Association | More NASA Hydrogen from Water and Sunlight | Research & Development; concerning: "United States Patent 4,051,005 - Photolytic Production of Hydrogen; 1977; United Technologies Corporation; The invention described herein was made in the course of a contract with the National Aeronautics and Space Administration. Hydrogen and oxygen are produced from water in a process involving the photo-dissociation of molecular bromine with radiant energy at wavelengths within the visible light region (and) wherein the source of radiation is sunlight. A process for producing hydrogen from water";
for definitive confirmation of that statement's accuracy.)
The feasibility of the strategy involving the recycling of a sacrificial electron donor and the direct supply of protons and electrons released from water oxidation catalysts to photocatalysts for the reduction of CO2 to fuels has been demonstrated.
It would be advantageous to capture CO2 from the atmosphere or the exhaust of factories/power stations and convert it to fuel by using a sustainable source of energy such as sunlight. This option solves the problems of global warming and the sustainable energy shortage simultaneously.
Water oxidation and the subsequent reduction of CO2 are required. This review mainly discusses the photocatalytic conversion of CO2 to fuels using semiconductors, but also presents a comparison of the related thermochemical conversion of CO2 to fuels via the reduction–oxidation of metal oxides.
Thermochemical conversion of CO2 to fuels: The energy from the sun that reaches the Earth (is such that) all the energy consumed on the Earth in one year can be supplied from solar energy in only one hour. To utilize the enormous energy provided by the sun, two-step thermochemical cycles to dissociate CO2 and H2O using metal oxide redox reactions have been proposed. Nonstoichiometric oxides such as cerium oxide are partially reduced at higher temperatures .... releasing O2 under concentrated solar radiation, and then are oxidized again by reacting with CO2 and H2O at lower temperatures ... .
(Which re-oxidation of the reactive metal "at lower temperatures" "with CO2 and H2O", by way of redundant explanation, generates Carbon Monoxide and Hydrogen, which can then be catalytically reacted together to form hydrocarbons. The text goes into some detail comparing the use of Cerium Oxide, versus Zinc and Iron Oxides for CO2 reduction reactions. Such employment of reactive metals and their oxides for cyclic use in various Carbon conversion technologies has some intriguing potentials, as seen, for one example, in our report of:
West Virginia Coal Association | Japan, Switzerland and Indiana Oxygen Donor Coal Gasification | Research & Development; concerning: "Coal Gasification Using the ZnO/Zn Redox System; Energy & Fuels; 1996; Tokyo Institute of Technology, Japan; Laboratory for Energy and Process Technology, Paul Scherrer Institute, Switzerland; (and,) Mechanical Engineering Department, Valparaiso University, Indiana; A two-step thermochemical process ... for converting coal to high-quality synthesis gas. In the first, high temperature, endothermic step, coal is reacted with zinc oxide to form metallic zinc and an H2-CO gas mixture. In the second, low temperature, exothermic step, zinc is used for splitting water and producing hydrogen and zinc oxide".
Other, related technologies we have reported confirm that Solar radiation can provide enough energy and heat to drive the processes.)
Photon energy conversion of CO2 to fuels with water (with) TiO2 photocatalysts:

The photon energy of sunlight can be converted to electric energy using solar cells and to chemical energy using photocatalysts. The development of photocatalysts to convert solar energy to chemical energy is an indispensable option for storing energy (and, the photocatalytic) conversions of CO2 to fuels with water using semiconductors are summarized (in an accompanying table, which shows the products of such Carbon Dioxide conversion to include Methane, Methanol and Formaldehyde).
Photon energy conversion of CO2 to fuels using hydrogen: Photocatalytic conversion of CO2 to methane or CO using hydrogen: The reduction of CO2 with hydrogen is thermodynamically favorable compared to the reduction with water ... (and, we would) assume that hydrogen is supplied via sustainable ways, e.g., photocatalytic water reduction utilizing sunlight ... .
(Which is perfectly feasible, as we noted above with linkage to our earlier report concerning: "United States Patent 4,051,005 - Photolytic Production of Hydrogen; 1977; United Technologies Corporation". The point of the discussion being, that, if we already have Hydrogen, then the chemical reduction and conversion of Carbon Dioxide becomes easier and requires much less energy to accomplish than it does if we're using Methane and/or Water as the Hydrogen-donating co-reactants.)
Electron donors: The regeneration of a sacrificial electron donor in the photoreduction of CO2 was reported to make the overall catalytic reaction system cyclic.
Further efficiency improvements for the CO2 conversion are highly expected by the combination of different photocatalysts and the use of new reaction systems. In particular, the combination of water photosplitting to form hydrogen (or protons and electrons) and CO2 photoreduction with the formed hydrogen (or the formed protons and electrons) can potentially boost the efficiency of CO2 conversion."
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The article is much more detailed and complete than our excerpts might indicate; and, accompanying charts and tables offer a slightly broader selection of potential CO2 recycling products than we've indicated via our excerpts. But, the authors are cautionary, urging that further work needs done to improve the efficiencies; some of which they indicate they themselves have done.
We're really not so certain much more work does, in fact, need to be done. The light-driven conversion of CO2 and Water vapor into Methane should, really, be all we need, as nice as it might be to directly produce such things as Methanol and Formaldehyde from CO2; that, since, as seen, for only one example, in:
West Virginia Coal Association | Even More Japan CO2 + Methane = Hydrocarbon Syngas | Research & Development; concerning: "United States Patent 6,656,978 - Producing Liquid Hydrocarbon Oil from Hydrocarbon Gas and Carbon Dioxide; 2003; Chiyoda Corporation (Japan); A process for the production of a liquid hydrocarbon oil from a gas feed containing a lower hydrocarbon and CO2, wherein the gas feed is mixed with H2O (and, wherein) a lower hydrocarbon ... such as methane ... may be used";
we can react any Methane we do make out of Water and Carbon Dioxide, via the technologies disclosed by our subject, "Recent Advances in the Photocatalytic Conversion of Carbon Dioxide to Fuels with Water and/or Hydrogen Using Solar Energy", with even more Carbon Dioxide, as recovered from whatever handy source, and thereby indirectly synthesize, via the intermediate production of a hydrocarbon synthesis gas, "liquid hydrocarbon oil".
Such use of the CO2-derived Methane, to recycle and convert into hydrocarbons even more CO2, would, we suspect, compensate for a lot of inefficiency in the underlying reaction, since such might help to free us from the outrageous inefficiencies of buying foreign OPEC oil; the inefficiencies of fighting foreign OPEC wars; the inefficiencies of subsidizing Big Oil's scrounging of secondary petroleum through mandated geologic sequestration of CO2 in leaky, nearly-depleted natural petroleum reservoirs; and, the inefficiencies of being extorted to no good purpose by our own government through the imposition of Cap and Trade taxes.
One more time:
Carbon Dioxide, as it arises in only a small way, relative to natural sources of emission, such as and especially the Earth's inexorable processes of planetary volcanism, from our economically essential use of Coal in the generation of truly abundant and affordable electric power, is a valuable raw material resource.
We can, according herein to Japan's Chiba University, using the freely-available energy conveyed to us in simple sunlig
ht, convert Carbon Dioxide, and Water, into hydrocarbon "Fuels".

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