United States Patent: 6527833
Yesterday, we reported on Virginia Tech's development of reforming processes, wherein Carbon Dioxide is reacted with Methane in order to synthesize higher hydrocarbons.
The United States Patent enclosed herein, we believe, is one result of their research. Close reading reveals that it is the refinement of a method intended to better prevent "reversal" of the Methane-Carbon Dioxide reforming reaction, a contingency we've noted in other reports of research and development of similar technology.
Comment follows excerpts from:
"United States Patent 6,527,833 - Hydrogen-Selective Silica Based Membrane
Date: March, 2003
Inventor: Ted Oyama, Virginia, et. al.
Assignee: Virginia Tech Intellectual Properties, Inc., Blacksburg, VA
Abstract: A new type of silica-modified membrane has been developed by the high-temperature, atmospheric-pressure CVD of Vycor glass. The new membrane, Nanosil, showed unprecedented selectivity to hydrogen (100%), without loss of permeability compared to the porous Vycor precursor. The membrane also showed high stability under hydrothermal conditions over prolonged time. The suitability of a
Rh/Al2O3 catalyst for the methane reforming with carbon dioxide was also demonstrated. The limitations imposed by thermodynamics on methane conversion have been circumvented by the use of membranes to preferentially remove hydrogen during reaction. The shortcoming of the Knudsen mode of diffusion was overcome by the development of the modified porous glass membrane.
Background: In recent years, increasing attention has been paid to global warming as a result of the release of greenhouse gases. The methane dry-reforming reaction provides a pathway to convert carbon dioxide, a problematic greenhouse gas, and methane, a plentiful natural resource, into syngas (a mixture of CO+H2).
Syngas is an industrially important feedstock that can be commercially transformed into ethylene glycol, MTBE, acetic acid, oxo alcohols, diesel, ethylene and several other important chemicals.
(And, ultimately, into Gasoline.)
Fischer and Tropsch ... were the first to propose the dry-reforming reaction for methane conversion to syngas. In recent years, many researchers have explored this route towards syngas production.
(Note: Keep in mind that "dry reforming" Methane means reacting it with Carbon Dioxide, as in "the methane reforming with carbon dioxide", above. And, we have earlier documented the work done with Methane by Fischer and Tropsch, which was related to their development of the indirect Coal-to-Liquid process now, almost generically, named for them.)
The conversion of methane in the fixed-bed mode of operation is limited by the reversibility of the reforming reaction. For such reversible reactions, preferential removal of one or more of the products during reaction will cause a shift in equilibrium, thereby overcoming thermodynamic limitations. Membranes can bring about such selective removal of species during reaction and hence reactors incorporating such membranes have been used to increase reaction yields. Membranes have also been used in applications where controlled introduction of reactant(s) is necessary to reduce hot spots in a catalyst bed or to avoid undesirable side reactions. Reactors incorporating membranes offer advantages over conventional fixed-bed reactors that include higher energy efficiency, lower capital and operating costs, compact modular construction, low maintenance cost, and ease of scale-up."
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Virginia Tech herein confirms the reality of a technology that would enable us to recycle Carbon Dioxide, by combining it with Methane, which can itself be synthesized, via the Sabatier reaction, from Carbon Dioxide; or, via gasification, from Coal; in order to produce both a slate of liquid hydrocarbon fuels and a range of plastics manufacturing raw materials, such as "ethylene glycol, ... oxo alcohols (and) ethylene".
Why, we are again compelled to ask, of anyone who might answer, are such Carbon Dioxide recycling technologies not now the focus of Federal policy initiatives and planning, and of public reportage, instead of Coal-crippling schemes and scams like Cap&Trade and Geologic Sequestration?