Due to recent developments concerning the productive chemical recycling of Carbon Dioxide which we are preparing to make report of, we wanted to begin providing some more background on a concept we ourselves find a bit difficult to grasp, much less to explain.
First, as is almost instinctively known to anyone who has taken high school chemistry or who ever watched Mr. Wizard, in that early foray into educational television, electricity can be employed to split some chemical compounds apart into their simpler molecular or elemental components.
The electrolysis of Water into Oxygen and Hydrogen is an obvious example; and, it is one we have made frequent reference to, as in our report of:
General Electric Hydrogen from Geothermal Energy | Research & Development; concerning: "United States Patent 7,331,179 - System and Method for Production of Hydrogen; 2008; Assignee: General Electric Company; Abstract: A technique is disclosed for a system and method for combined production of power and hydrogen utilizing the heat from a first working fluid heated by a geothermal energy source using a steam generator and an electrolyzer designed to receive the steam produced by the steam generator for the production of hydrogen and oxygen using electrolysis";
since the availability of elemental, molecular Hydrogen figures prominently in some established process for the conversion of both Coal and Carbon Dioxide into Hydrocarbons.
And, it's important to note that Carbon Dioxide, as well, can be electrolyzed and broken down into it's Oxygen and Carbon Monoxide constituents, especially in the presence of certain catalytically-enhanced electrodes, as somewhat outlined in, for just one example, our report of:
West Virginia Coal Association | USDOE Idaho Lab Recycles More CO2 | Research & Development; concerning: "Model of High Temperature H2O/CO2 Co-electrolysis; 2007; Research Organization: Idaho National Laboratory (INL); Sponsoring Organization: USDOE; Abstract: A three-dimensional computational fluid dynamics (CFD) model has been created to model high temperature co-electrolysis of steam and carbon dioxide in a planar solid oxide electrolyzer (SOE) using solid oxide fuel cell technology. A research program is under way at the Idaho National Laboratory (INL) to simultaneously address the research and scale-up issues associated with the implementation of planar solid-oxide electrolysis cell technology for syngas production from CO2 and steam. With the price of oil currently around $60 / barrel, synthetically-derived hydrocarbon fuels (synfuels) have become economical. Synfuels are typically produced from syngas – hydrogen (H2) and carbon monoxide (CO) -- using the Fischer-Tropsch process, discovered by Germany before World War II. Syngas (can) be produced via separate electrolysis of steam and CO2. There are, however, significant advantages to electrolyzing steam and CO2 simultaneously".
Conversely, in addition to electrolysis, there are processes of electro-synthesis, more properly called, for reasons of chemical nomenclature we can't go into here, "electrochemical reduction". The concept implying that electricity can be used not just to split stuff apart, but, as well, to weld stuff, i.e., in this case, atoms and molecules, together.
One example of such "electro-synthesis" or "electrochemical reduction" about which we've reported can be accessed via:
USDOE 1976 Atmospheric CO2 to Methanol | Research & Development; concerning: "United States Patent 3,959,094 - Electrolytic Synthesis of Methanol from CO2; 1976; The USA as represented by the USDOE; Abstract: A method and system for synthesizing methanol from the CO2 in air using electric power";.
the full Disclosure of which reveals how electricity can be applied to a water solution of a potassium salt which has absorbed Carbon Dioxide from the air, with the result being the synthesis of Methanol.
We'll note, in passing and without reference to prior reports documenting the facts, excepting the one following, that light energy can be utilized, in addition to or instead of, and sometimes in concert with, electricity to achieve the same ends.
Our one exception is our report concerning:
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";
since it, especially, demonstrates that not only can the processes of splitting both Water and Carbon Dioxide be accomplished while both the H2O and the CO2 are in the form of vapors, i.e., while they are in the "gas phase", the synthesis of hydrocarbons from the resultant products can proceed simultaneously, with the entire process being driven by a supply of externally-supplied energy.
Those, in essence, are the concepts behind the technology established by our subject herein; which concepts, again, serve as the bases of some more recent developments concerning the more efficient and more productive chemical recycling of Carbon Dioxide.
We'll attempt to explain a bit further via comments inserted within and appended to excerpts from the initial link in this dispatch to:
"United States Patent 4,959,131 - Gas Phase CO2 Reduction to Hydrocarbons
Date: September, 1990
Inventors: Ronald Cook and Anthony Sammells, IL
Assignee: Gas Research Institute, Chicago
(Note that we have many times cited the work of Chicago's Gas Research Institute, as in, for one related example of combined electricity-driven liquid phase H2O/CO2-electrolysis and hydrocarbon synthesis:
West Virginia Coal Association | Chicago Recycles CO2 to Methane | Research & Development; concerning: "United States Patent 4,609,440 - Electrochemical Synthesis of Methane; 1986; Assignee: Gas Research Institute, Chicago; Abstract: A method is described for electrochemically reducing carbon dioxide to form methane by electrolyzing an aqueous solution containing carbon dioxide utilizing a cathode which comprises ruthenium. If desired, solar energy can be utilized to provide the potential for the electrolyzing. In such an instance, solar energy is, in essence, stored as chemical energy which can later be recovered from the methane".)
Abstract: A process and apparatus for gas phase electrochemical reduction of CO2 and/or CO to hydrocarbons at ambient temperatures. The process is carried out by passing an electrical current between a cathode in contact with one side of a hydrogen ion conducting solid polymer electrolyte and an anode in ionic communication with the opposite side of the solid polymer electrolyte. In one embodiment, the anode material may be in contact with the opposite side of the hydrogen ion conducting solid polymer electrolyte, and in another embodiment, an anode may be separated from the opposite side of the solid polymer electrolyte by an aqueous inorganic salt solution. At least one of CO2 and CO are passed in contact with the cathode and hydrogen ions passing through the solid polymer electrolyte reduce at least a portion of the CO2 and CO to gaseous hydrocarbon products such as CH4 (Methane) and C2H4 ("Ethylene", aka "ethene"; a colorless flammable gas) at the solid polymer electrolyte/cathode interface.
Claims: A process for gas phase electrochemical reduction of at least one of CO2 and CO to gaseous hydrocarbon products at solid polymer electrolyte cells, said process comprising: passing a current between a cathode in contact with one side of a hydrogen ion conducting solid polymer electrolyte and an anode in ionic communication with the opposite side of said solid polymer electrolyte, said cathode comprising a metal electrocatalyst deposited on said electrolyte and capable of providing adsorption sites for at least one of CO2 and CO and chemisorbed hydrogen species and faradaically generated hydrogen species in proximity to said at least one of adsorbed CO2 and CO; passing at least one of gaseous CO2 and CO in contact with said cathode; passing hydrogen ions through said solid polymer electrolyte reducing at least a portion of said CO2 and CO to gaseous hydrocarbon products comprising CH4 and C2H4 at said solid polymer electrolyte/cathode interface; and removing said gaseous hydrocarbon products from the region of said cathode.
(Note, again, that it can be either CO2 or CO; both can be used, but both aren't needed. It can be Carbon Dioxide alone, if desired. The important thing to note is that the catalytic synthesis of Methane and/or Ethylene is taking place while all the ingredients are in a gaseous state and it is being driven in part by a supply of electricity, which makes the synthesis more effective and thorough.)
A process ... wherein said cathode metal electrocatalyst is selected from the group consisting of copper, nickel, rhodium, ruthenium, and mixtures thereof.
A process ... wherein said cathode metal electrocatalyst comprises copper.
A process ... wherein said cathode metal electrocatalyst is selected from the group consisting of copper, nickel, rhodium, ruthenium, and mixtures thereof.
A process ... wherein said cathode metal electrocatalyst comprises copper.
(Multiple additional claims specify how the copper "cathode metal electrocatalyst" is to be chemically treated and structured; and, what other metals, like nickel, it can be combined with.)
A process ... wherein said anode is a metal compatible with electrochemical hydrogen oxidation, said anode metal deposited on said opposite side of said solid polymer electrolyte (and) wherein said anode comprises platinum.
A process ... wherein said anode is a metal electrode separated from said opposite side of said solid polymer electrolyte by an aqueous inorganic salt solution (as chemically specified).
A process ... wherein said current is in an amount to result in current densities on said cathode of about 5 to about 50 mA cm2.
(50 milliamps per square centimeter isn't a whole lot of juice. This thing should be reasonably economical to operate, perhaps supplied with electricity generated by a source of environmental energy.)
A process ... wherein an electrochemical oxidation reaction providing organic synthesis takes place at said anode.
A solid polymer electrolyte cell comprising: a cathode in contact with one side of a hydrogen ion conducting solid polymer electrolyte and an anode in ionic communication with the opposite side of said solid polymer electrolyte, said cathode comprising a metal electrocatalyst deposited on said electrolyte and capable of providing adsorption sites for at least one of CO2 and CO and chemisorbed hydrogen species and faradaically generated hydrogen species in proximity to said at least one of adsorbed CO2 and CO.
Background and Field: This invention relates to a process for gas phase electrochemical reduction of CO2 and/or CO to CH4 and C2H4 at ambient temperatures. The process is carried out at a solid polymer electrolyte wherein a metal electocatalyst capable of providing adsorption sites for CO2 and/or CO and chemisorbed hydrogen species or faradaically generated hydrogen species in proximity to the adsorbed CO2 and/or CO is deposited on one side of the solid polymer electrolyte to function as a cathode. CO2 and/or CO is passed in contact with the electrocathode while hydrogen ion is passed through the solid polymer electrolyte from an anode portion of the cell capable of providing hydrogen. Formation of hydrocarbons occurs during electrochemical reduction of CO2 and CO at the metal/solid polymer electrolyte interface."
------------------------
We'll leave it at that, noting, especially, that what seem to us only low levels of electricity are required to help drive the efficient chemical combination and conversion of gaseous Carbon Dioxide and Hydrogen, in a low-energy, "ambient" temperature process, into such things as Methane and Ethylene.
We remind you, as we must, that should we elect, as one option herein, to synthesize Methane in such an electricity-facilitated
Standard Oil 1949 CO2 + CH4 + H2O = Hydrocarbon Syngas | Research & Development; concerning: "United States Patent 2,460,508 - Method and Means for Hydrocarbon Synthesis; 1949; Assignee: Standard Oil Company, Chicago; This invention relates to the synthesis of hydrocarbons (from) a gas comprising methane, oxygen and carbon dioxide";
combine that Methane with even more Carbon Dioxide, in a reforming process that results in the production of a synthesis gas suitable for catalytic chemical condensation into liquid hydrocarbon fuels.
But, the main point is, as will be emphasized in at least a few reports to follow, that low levels of electricity can be utilized, as they are herein, and as sunlight is used in our above citation of Penn State's "High-Rate Solar Photocatalytic Conversion of CO2 and Water Vapor to Hydrocarbon Fuels", to help drive and make more efficient the catalyzed chemical synthesis of hydrocarbons directly from blends of Hydrogen and Carbon Dioxide, and/or Carbon Monoxide, the "organic synthesis" stipulated herein, while both the H2 and the CO2 are in the gaseous state; in addition to, as in the USDOE process of "United States Patent 3,959,094 - Electrolytic Synthesis of Methanol from CO2" cited above, while all the raw ingredients are in a liquid, aqueous solution.
That fact figures prominently in much more recent developments demonstrating even further, that:
Carbon Dioxide, as it arises in only a small way, relative to natural sources of emission, such as volcanoes, from our economically essential use of Coal in the generation of abundant and truly affordable electric power, is a valuable raw material resource.
We can reclaim Carbon Dioxide, from whatever convenient source, and then, as via the process of our subject herein, "United States Patent 4,959,131 - Gas Phase CO2 Reduction to Hydrocarbons", efficiently convert that Carbon Dioxide into useful and commercially valuable products, such as Methane and Ethylene.