United States Patent: 4061475

We know that it is likely, by now, getting to be "old hat", but, we feel it necessary to continue to emphasize the fact, that:

If we really do want a clean and reliable source of what we all think of as "natural" gas, and there are good reasons why we should, then there are ways to go about getting it that don't, like the Marcellus Shale Gas tulip frenzy sweeping the Coal Country public press nowadays, endanger water tables with toxic "fracking" chemicals or clutter public lands with innumerable drilling rigs.

 

 

As seen, for just one instance, in our earlier report:

Texaco Clean Methane from High-Sulfur Coal | Research & Development; concerning the: "United States Patent 3,928,000 - Clean Methane ... from High-Sulfur Containing Hydrocarbonaceous Materials; 1975;  Assignee: Texaco Incorporated, NYC, NY; Abstract: This is an improved process for converting low-cost high-sulfur containing hydrocarbonaceous materials into a clean methane-rich gas stream which may be burned as a fuel without contaminating the atmosphere";

clean Methane can be synthesized from even the "dirtiest" Coal.

We make reference to that specific process since it is one of the two Texaco Coal conversion technologies cited as precedent art by the German inventors of the Coal-to-Methane process we report herein.

We'll address the other Texaco citation, along with some additional information, and the implications of it all, following excerpts from the initial link in this dispatch to:

"United States Patent 4,061,475 - Process for Producing a Gas which can be Substituted for Natural Gas

Date: December, 1977

Inventor: Friedrich Moller, et. al., Germany

Assignee: Metallgesellschaft AG, Frankfurt am Main

Abstract: A high methane gas which can be substituted for natural gas is produced from a primary gas made by the gasification of coal ... under superatmospheric pressures. The primary gas is purified to remove catalyst poisons and is scrubbed to remove carbon dioxide to a residual content below 2% by volume. The water vapor to carbon monoxide volume ratio of the scrubbed gas is adjusted ... and is then passed through a reaction zone containing a shift conversion catalyst and a methanation catalyst ... .

Claims: A process for producing a high-methane gas which can be substituted for natural gas, from a primary gas containing 35-44% by volume hydrogen, 15-20% by volume carbon monoxide and 28-32% by volume carbon dioxide produced by the gasification of coal with water vapor and oxygen ... (and): 

purifying said primary gas by removing catalyst poisons and removing carbon dioxide to a residual content below 2% by volume; adjusting the water vapor to carbon monoxide volume ratio (as specified, and):

passing said gas ... through one reaction zone containing only a methanation catalyst containing 20-60% by weight of nickel on a support which is resistant to water vapor, the temperature of the gas (and):

supplying the gas leaving the reaction zone to a final methanation stage to produce a high-methane gas; and: removing residual carbon dioxide from said high-methane gas to produce said gas to be substituted for natural gas. 

The process ... wherein said (catalyst) support ... is selected from the group consisting of alumina, magnesium silicate and magnesium spinel.

(Since the catalyst itself is based on Nickel, there's nothing exotic or expensive in either the catalyst or, as immediately above, the "catalyst support" upon which the Nickel is deposited.)

Description and Background: This invention relates to a process of producing a high-methane gas, which can be substituted for natural gas, from a primary gas which has been produced by a gasification of coal.

Such gas which can be substituted for or mixed with natural gas should contain at least 90% by volume methane and less than 2% by volume hydrogen.

A residual carbon dioxide content is generally not disturbing.

(In fact, any "residual carbon dioxide content" might even be pleasing, as we discuss further on.)

It is known that coal ... can be gasified with water vapor and oxygen under superatmospheric pressure and at elevated temperatures to produce a raw gas which contains carbon oxides in excess of its hydrogen content.

These oxides of carbon contained in the gas produced by gasification are hydrogenated to produce methane preferably in contact with a high-activity hydrogenation catalyst, which contains metallic nickel as its active component.

The reaction of CO and CO2 with hydrogen to produce methane and water is also referred to as methanation

Because CO2 can be scrubbed in a simple manner from the product gas after the synthesis of methane, CO2 need not be hydrogenated to methane as completely as possible.

(Although, with added Hydrogen from another source, the "CO2" could, according to this variation on the 1912 Nobel-winning Sabatier reaction, be completely hydrogenated to Methane. The disclosure goes on in some rather complex detail about how the water gas shift reaction, which takes place between H2O and Carbon Monoxide, and produces both more Hydrogen and Carbon Dioxide, can be performed to prepare the synthesis gas for the methanation reaction; and, about how some contaminants, such as Hydrogen Sulfide, are to be removed. In any case, the gist of it is that there will be more CO2 produced, through the overall synthesis gas preparation, than is consumed in the ultimate methanation; but, not a lot more.  Comment concerning that small residual amount of CO2 follows the excerpts.)

Summary: This invention provides a process which ... can be carried out in a simpler manner and at lower costs than the processes known in the art.

Both catalysts may be of known type. For instance, the shift conversion catalyst may be a mixture of iron oxide and chromium oxide. The methanation catalyst usually contains 20-60% by weight nickel on a support which is resistant to water vapor. The support may consist of, e.g., alumina, magnesium silicate, or magnesium spinel."

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Our read of it is that any Carbon Dioxide generated in the initial Steam gasification of the Coal, which could be thirty percent of the product gas, is to be removed and separated from the process; but, that the CO2 produced in the water gas shift reaction, which generates more Hydrogen, is consumed almost entirely in the Methane synthesis, which results in a product consisting of "at least 90% by volume methane".

And, that's okay, since, as seen in:

Germany Gasifies Coal with CO2 and H2O | Research & Development; which concerns: "United States Patent 4,347,064 - Process of Gasifying Fine-Grained Solid Fuels; 1982; Assignee: Metallgesellschaft AG, Frankfurt am Main; Abstract: A process of gasifying fine-grained solid fuels for the production of a product gas that contains hydrogen, carbon oxides and methane comprises a treatment with steam, oxygen and/or carbon dioxide";

the same folks who bring us our subject herein, US Patent 4,061,475, know that most, if not all, of that coproduct CO2, separated before the water gas shift reaction, can be recycled back into the initial Coal gasification to produce more Carbon Monoxide.

And, as seen in:

Netherlands & Germany CO2 + CH4 = Hydrocarbon Syngas | Research & Development; concerning: "United States Patent 5,989,457 - Process for the Production of Synthesis Gas; 1999; Assignee: Mannesmann & K.T.I. Group, Germany; Abstract: A catalyst for the production of synthesis gas (CO and H2) by reaction of CO2 and CH4 ... . A process for making CO/H2 -synthesis gas comprising: contacting a gas containing one of CO2, CH4, hydrocarbons or mixtures thereof with a (specified) catalyst";

they also know, in Germany, how to react any residual Carbon Dioxide that might be left over with some of the product Methane, in order to generate even more hydrocarbon synthesis gas.

Finally, to make this long report even longer, following is the second of the US Patents, for the conversion of Coal into Methane, issued to Texaco, which the inventors of our subject, US Patent 4,061,475, herein cite, in their full Disclosure, as prior art:

"United States Patent: 3927999 - Methane-rich Gas Process

Date: December, 1975

Inventors: Edward Child, NY, et. al.

Assignee: Texaco Incorporated, NYC

Abstract: A methane-rich gas stream is produced by catalytic methanation of synthesis gas feed comprising H2 and CO.

Claims: (A) process for producing a methane-rich gas stream by the partial oxidation of hydrocarbonaceous fuel with a free-oxygen containing gas in the presence of a temperature moderator to produce a process gas stream which is subsequently subjected to catalytic methanation the improvement comprising the steps of:

(1) reacting said hydrocarbonaceous fuel feed by partial oxidation with substantially pure oxygen comprising at least 95 % O2 and a temperature moderator selected from the group consisting of H2O, CO2, and mixtures thereof.

(Thus, again: Added Carbon Dioxide can be utilized as one of the agents of Coal gasification. The H2O supplies the Hydrogen; and, use of "95% O2" forestalls production of unwanted Nitrogen oxides. Further, the Oxygen can be obtained, as seen for just one example, in our report:

Chicago Hydrogen from H2O | Research & Development; concerning: USP 4,793,910 - Photoelectrochemical Cell for Unassisted Photocatalysis; 1988; Assignee: Gas Research Institute; Abstract: A multielectrode photoelectrochemical cell ... which ... contains two bipolar electrode panels for photoelectrochemical reactions such as water photolysis to produce H2 (and) O2";

in a process driven by sunlight that, in addition to Oxygen, also generates Hydrogen, which, as seen another of our reports:

NASA Rocket Fuel from CO2 | Research & Development; which relates, in part, that: "methane can be manufactured ... via the Sabatier process: Mix some carbon dioxide (CO2) with hydrogen (H), then heat the mixture to produce CH4 and H20 -- methane and water";

can then be used to convert even more Carbon Dioxide, recovered from whatever source, into even more Methane.)

(2) cooling the process gas stream (and) removing therefrom particulate carbon; (and:)

(3) introducing the process gas stream ... into a catalytic methanation zone where said H2 and CO are reacted together ... to produce an effluent gas stream comprising (primarily) CH4.

The process ... wherein at least a portion of the hydrocarbonaceous fuel feed ... comprises a pumpable slurry of ... coal ... in admixture with a liquid selected from the group consisting of liquid hydrocarbon fuel and water (and) wherein the ... liquid hydrocarbon (is) coal tar, coal oil, ... and mixtures thereof.

The process ... wherein the sulfur-resistant methanation catalyst ... comprises (a specified percentage of Cobalt Oxide in combination with Molybdenum Oxide) and the remainder alumina.

Background and Field: This invention relates to an improved process for the production of methane-rich gas.

The product gas may be burned without polluting the environment. 

It is imperative that alternate sources of low-cost gaseous heating fuels be developed.

One economic benefit of the subject invention is the elimination of the troublesome water-gas shift reaction considered essential by prior art processes to adjust the H2/CO ratio of the feed gas stream to the methanator.

(Which thus eliminated "water gas shift reaction", we remind you, would otherwise, as well as producing additional Hydrogen for the methanation reaction, also produce more Carbon Dioxide. Thus, one potential source of CO2 within the process itself is eliminated.)

Summary: It was unexpectedly found that in the catalytic methanation of synthesis gas, i.e., mixtures of H2 and CO, when the mole ratio H2 /CO of the synthesis gas feed to the methanator is in the narrow range of about 0.5 to 1.15, the amount of CH4 produced is substantially increased by adjusting the (percentage of)  H2O in the feed gas to a value in the range of 0.1 to 15.

(Adding a little Water to the syngas can, in other words, improve Methane production.)

One embodiment of the subject invention (can) produce a methane-rich product gas stream comprising about 70 to 98 % methane, or higher.

(Any) particulate carbon ... may be removed from the effluent gas stream by well known scrubbing techniques (and) be recycled to the gas generator as a portion of the feedstock.

The stream of CO2 (which can be recovered) has a purity of more than 98.5 percent and may therefore be used for organic synthesis."

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Note that the above US Patents cited by our subject German inventors are in addition to even another Texaco Coal-to-Methane technology we earlier made report of via:

Texaco 1975 Methane from Coal | Research & Development; concerning: "US Patent 3,922,148 - Production of a Methane-rich Gas; 1975; Assignee: Texaco Development Corporation; Abstract: This is an improved continuous process for producing a clean methane-rich gas stream without the concomitant formation of particulate carbon which would ordinarily decrease the efficiency of the process and shorten the life of the catalyst".

Interesting, isn't it, that a one-time member of the Big Oil club, since assimilated into the Chevron conglomerate, in the disclosure of their process of United States Patent 3,927999, suggests that a "98.5%" pure stream of Carbon Dioxide, which can be reclaimed from a process that converts Coal into "98%" pure Methane, can "be used for organic synthesis"?

We have some thoughts concerning what an appropriate "organic synthesis" in which to use all of that Carbon Dioxide might be; and, they all center around technologies such as that disclosed in our report of yet another Texaco technology, as seen in:

Texaco Recycles CO2 to Methanol & Methane | Research & Development; concerning: "United States Patent 4,523,981 - Means and Method for Reducing Carbon Dioxide to Provide a Product; 1985; Assignee: Texaco, Incorporated; Abstract: A process for reducing carbon dioxide to at least one useful product includes two redox couple electrolyte solutions separated by a first membrane having photosensitizers. The carbon dioxide to be reduced is separated from one of the redox couple electrolyte solutions by another membrane having a catalyst. Water provides hydrogen ions which participate in the reduction of carbon dioxide via a separator. In the operation both membranes are illuminated and produce excited solar sensitizers which cause electron transfer from a first redox solution to the second redox solution and then to the carbon dioxide to react with the hydrogen ions, reducing the carbon dioxide to provide at least one product ... (including) formic acid (and/or) formaldehyde (and.or) methanol (and/or) methane";

wherein that pure CO2 can be converted into both the highly-versatile liquid fuel, Methanol, and, even more Methane, which, as seen in even another earlier report:

1941 CO2 + Methane = Liquid Hydrocarbon Fuels | Research & Development; concerning: "United States Patent 2,243,869 - Method of Synthesizing Liquid Hydrocarbons; 1941; Assignee: M.W. Kellogg Company, New York; (This) invention relates to a method of synthesizing liquid hydrocarbons and more particularly to a method of converting methane and like light hydrocarbon gases into hydrocarbons suitable for use as a motor fuel ... (via) the oxidation of methane to form mixtures of carbon monoxide and hydrogen and the synthesis of the synthesis gas thus form into liquid hydrocarbons. One object of our invention is to provide a method for synthesizing liquid hydrocarbons from light, low boiling gaseous hydrocarbons, such as methane. (And) only steam and carbon dioxide (need be) employed for converting methane into synthesis gas";

can be reacted with even more Carbon Dioxide, recovered from whatever convenient and rewarding source; with both of them being converted through such reaction into "mixtures of carbon monoxide and hydrogen", which can then be used in "the synthesis" of  "hydrocarbons suitable for use as a motor fuel".


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