Conversion of carbon dioxide to carbon monoxide
We have many times documented, and made reference to, Eastman Chemical Company's operation of a plant in Kingsport, Tennessee, where they convert Coal on a commercial basis into the valuable liquid fuel, Methanol - a versatile alcohol which can itself be used as a raw material in the manufacture of plastics and other products of high value; including, via ExxonMobil's "MTG"(r) technology, for one instance, Gasoline.
Eastman's orocess is an "indirect" Coal conversion technique, wherein Coal is first converted into synthesis gas, "syngas", a mixture of Hydrogen and Carbon Monoxide, which is then catalytically condensed into the liquid Methanol.
We have also documented the development of "bi-reforming" and "tri-reforming" technologies, some, developed by the petroleum industry, dating back to the WWII era, in which Carbon Dioxide can be reacted with Methane, and/or Steam, and thus made to generate a very similar hydrocarbon synthesis gas.
"The catalytic steam reforming of mixtures of methane and carbon dioxide to produce mixtures of hydrogen and carbon monoxide has been practiced for many years on a commercial scale."
Keep in mind that Methane can itself be synthesized, via the 1912 Nobel-certified Sabatier process now being further refined by NASA, from Carbon Dioxide; or, via long-known Steam gasification techniques, from Coal.
Comment follows additional excerpts from:
"United States Patent 5,068,057 - Conversion of Carbon Dioxide to Carbon Monoxide
Date: November, 1991
Inventors: Bruce Gustafson and James Walden, Tennessee
Assignee: Eastman Kodak Company, New York
Abstract: Method for the conversion of carbon dioxide to a carbon monoxide-rich synthesis gas mixture is disclosed. The invention comprises contacting carbon dioxide with at least one hydrocarbon in the presence of a catalyst selected from platinum or palladium supported on an alumina or silica-alumina support ... .
(By the way, the "silica-alumina", specified as Eastman's catalyst "support", sounds very similar to the composition of the zeolite mineral specified by ExxonMobil as key to their "MTG"(r), Methanol-to-Gasoline, process; wherein the Methanol, as we've thoroughly documented, is posited to be made from Coal. - JtM)
This invention relates to the conversion of carbon dioxide to carbon monoxide. In one aspect, this invention relates to the reforming of hydrocarbon/carbon dioxide mixtures to produce synthesis gas.
Background: The catalytic steam reforming of mixtures of methane and carbon dioxide has been practiced for many years on a commercial scale. One of the disadvantages associated with the production of synthesis gas by the steam reforming of methane is that the product gas mixtures are limited by the reaction stoichiometry to hydrogen/carbon monoxide ratios of 3:1 or higher.
The addition of carbon dioxide to a steam reformer can result in lower hydrogen/carbon monoxide ratios ... .
(And it) would be desirable, for a variety of applications ... to directly produce carbon monoxide-rich synthesis gas mixtures.
In accordance with the present invention, there is provided a process for the continuous preparation of a mixture of hydrogen and carbon monoxide ... by continuously contacting ... carbon dioxide with at least one hydrocarbon with a fixed bed of supported catalyst ... .
Hydrocarbons contemplated for use in the practice of the present invention ... include methane ... .
(An) advantage of the process is that the catalysts ... are commercially available ... and do not require any special components or techniques of manufacture.
Claims: (A) process for the continuous preparation of a mixture of hydrogen and carbon monoxide ... which comprises contacting ... carbon dioxide and at least one hydrocarbon with a fixed bed of supported catalyst (and) wherein the said hydrocarbon is methane ... ."
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Eastman goes on to explain that the mixtures of the Carbon Dioxide and Methane, or other gaseous hydrocarbon reactants, can be varied, with perhaps a little Steam added, although the process is specified to be "anhydrous", to produce a synthesis gas with a controllable and adjustable ratio of Carbon Monoxide and Hydrogen. The resulting synthesis gas could then, we conjecture, be catalytically condensed into a variable selection of liquid hydrocarbons; although we presume, based on Eastman's current Coal-to-Methanol conversion operations in Tennessee, that Methanol is the final product primarily intended.
In any case, again: Carbon Dioxide, as arises in a small way, relative to natural sources of emission, such as volcanoes and seasonal vegetative rot, from our varied and productive uses of Coal, is a valuable raw material resource.