The, very nearly four decades old, Atlantic Richfield technology we report herein, as revealed by the United States Patent we enclose, confirms some earlier documentation we have provided you concerning the fact that exhaust, or "tail", gas, arising from the catalytic condensation of Coal-derived synthesis gas into liquid hydrocarbons, can be made so as to have some residual chemical value which can be further exploited.
Interestingly, ARCO's point, as explained herein by one of their scientists we have cited previously, seems to be that Coal synthesis gas can be generated in such a way that it has too much Hydrogen to be consumed in the initial catalytic synthesis of liquid hydrocarbons.
The tail gas is then left with some un-reacted Hydrogen; and, ARCO's take on how to use that extra Hydrogen is somewhat intriguing:
They add externally-supplied Carbon Dioxide to it, to make an additional syngas mixture.
As in many of Big Oil's patents on, essentially, Carbon conversion technologies, the seemingly-offensive four-letter word, Coal, is avoided to the point of amusement.
Some excuse can be made for ARCO herein, though, since the Disclosure is actually centered on the technicalities of chemical reactions, regardless of the source of the reactants.
One abbreviated extract, we serve up as a forward, however, reveals the secret, as in:
"A method ... wherein said feed gas is obtained from ... liquefaction of coal".
That fact is at least obliquely, sparsely, perhaps grudgingly, confirmed in other passages, with summary comment appended, excerpted from the enclosed link to and attached file of:
"United States Patent 3,730,694 - Fuel Gas Upgrading
Date: May, 1973
Inventor: Donald Wunderlich, TX
Assignee: Atlantic Richfield Company, NY
Abstract: A method for upgrading a fuel gas feed by subjecting the feed gas to conditions which convert carbon monoxide to methane, saturate olefins, remove sulfur, and, if necessary, adding or retaining carbon dioxide to react with excess hydrogen after conversion of the carbon monoxide ... thereby providing a product gas which has an increased hydrocarbon content and heating value ... .
Background: Heretofore, off gases from various industrial operations; e.g., operations where synthetic crude oil is obtained from the liquefaction of coal ... have low heating value ... and contain a substantial amount of hydrogen and carbon monoxide.
Summary: According to this invention, the above low value gases are upgraded to a pipeline quality gas ... .
An upgraded fuel gas product is provided (by) treating the gas ... so as to utilize the hydrogen present in the gas to saturate the olefins present and to react with the carbon monoxide to convert same into methane (with) sufficient carbon dioxide being provided ... (to) ... the stream ... to react with any remaining hydrogen and convert the carbon dioxide to methane ... .
The gaseous product has a substantially increased hydrocarbon content with minimum free hydrogen and carbon dioxide content.
In addition, ... the product gas is also a low sulfur fuel gas.
Accordingly, it is an object of this invention to provide a new and improved method for upgrading low heating value off gases ... obtained from operations which produce a synthetic crude oil product.
Generally, the feed gas ... contains hydrogen, carbon monoxide (and) methane (and) can contain other materials such as hydrogen sulfide ... .
(A) preponderant amount can be hydrogen ... so that .. substantial amounts of carbon dioxide can be added from external sources.
The feed gas, after addition of any carbon dioxide, is then ready for hydrogenation ... and desulfurization.
Claims: A method for upgrading a fuel gas feed containing hydrogen, carbon monoxide, methane, saturated and unsaturated hydrocarbons (by) providing carbon dioxide in an amount such that after carbon monoxide has reacted with the hydrogen present to form methane ... sufficient carbon dioxide is present to react with substantially all the remaining hydrogen ... to form methane.
(And, a) method ... wherein said feed gas is obtained from ... liquefaction of coal."
-----------------
In sum, "off gases from operations ... where synthetic crude oil is obtained from the liquefaction of coal" can be further reacted with "substantial amounts of carbon dioxide ... from external sources" and made thereby "to form methane".
There would be technicalities involved in the initial Coal gasification, to insure that truly worthwhile amounts of unreacted Hydrogen were present in the "low heating value off gases" that were co-generated by such a process for the "liquefaction of coal". But, those technicalities would likely only center around the best way to add supplemental H2O to the gasification process.
And, we remind you:
Once we have the "methane" - as formed herein by reacting a tail gas obtained from a process centered on the "liquefaction of coal" with "substantial amounts of carbon dioxide ... from external sources" - such Methane can then be reacted, in bi-reforming and tri-reforming processes, as explained most recently by scientists Chunsan Song and Craig Grimes at Penn State University, all as we have previously documented, with even more CO2 "from external sources", and made thereby to form valuable products such as Methanol.
In any case, the sum of it is:
We can convert Coal into liquid hydrocarbons; and, we can utilize waste gas from such Coal liquefaction processes to recycle externally-supplied Carbon Dioxide.
Does anyone, can anyone, out there have a problem with that?
As herein, Carbon Dioxide, as arises in a small way, relative to natural sources of emission, such as volcanoes, from our varied and productive current uses of Coal, is a raw material resource of potentially great value.