United States Patent: 5753143

Since it's now clear, as we most recently documented, for just one example, in our report of:

West Virginia Coal Association | US Gov Hires Penn State Bugs to Convert CO2 to Methane | Research & Development; concerning: "US Patent Application 20090317882 - Electromethanogenic Reactor and Process for Methane Production; 2009; Assignee: The Penn State Research Foundation; Abstract: Increasing competition for fossil fuels, and the need to avoid release carbon dioxide from combustion of these fuels requires development of new and sustainable approaches for energy production and carbon capture. Biological processes for producing methane gas and capturing carbon from carbon dioxide are provided according to embodiments of the present invention which include providing an electromethanogenic reactor having an anode, a cathode and a plurality of methanogenic microorganisms disposed on the cathode. Electrons and carbon dioxide are provided to the plurality of methanogenic microorganisms disposed on the cathode. The methanogenic microorganisms reduce the carbon dioxide to produce methane gas ... . Government Interests: This invention was made with government support under Contract Nos. BES-0401885 and CBET-0730359 awarded by the National Science Foundation. The government has certain rights in the invention";

that we can efficiently convert Carbon Dioxide, recovered from whatever handy source, into Methane, we wanted herein to reaffirm another fact, such as that expressed, for only two out of now many examples, in:

Standard Oil 1987 CO2 + CH4 = Syngas | Research & Development; concerning: "United States Patent 4,690,777 - Production of Synthesis Gas; 1987; Assignee: The Standard Oil Company; Abstract: Gas mixtures containing at least hydrogen and carbon monoxide are prepared by reforming hydrocarbons in the presence of a catalyst ... . A process for reforming light hydrocarbons ... comprising contacting the light hydrocarbons with carbon dioxide ... (and) wherein the light hydrocarbon is methane. (Gas) mixtures containing carbon monoxide/hydrogen ratios of 1/1 or 1/2 are particularly useful as feed gases in processes for producing higher hydrocarbons and oxygenated derivatives, such as Fischer-Tropsch and alcohol synthesis processes"; and:

Standard Oil 1952 CO2 + CH4 + H2O = Syngas | Research & Development; concerning: "United States Patent 2,593,584 - Reforming Hydrocarbon Gases; 1952; Assignee: Standard Oil Development Company;

Abstract: The present invention relates to an improved process for producing gas mixtures containing CO and H2 from hydrocarbon gases by a reforming reaction with CO2 or (with) steam and CO2 ... particularly

when used for the production of gas mixtures suitable as feed gases for the catalytic synthesis of normally liquid hydrocarbons";

which is, that, once we have the Methane, made, for just one example, in the Penn State process of "US Patent Application 20090317882 - Electromethanogenic Reactor and Process for Methane Production", from Carbon Dioxide, we can react that CO2-based Methane with even more Carbon Dioxide, and thereby produce a synthesis gas blend of Carbon Monoxide and Hydrogen, suitable "for producing higher hydrocarbons".

That plain truth, that Carbon Dioxide can be productively consumed, through reactions with Methane, in the generation of hydrocarbon synthesis gas, is confirmed herein by another highly-respected institution of higher learning, as seen in excerpts from the initial link in this dispatch to:

"United States Patent 5,753,143 - Process for the Carbon Dioxide Reforming of Methane

Date: May, 1998

Inventors: Ramanath Bhat and Wolfgang Sachtler, Illinois

Assignee: Northwestern University, Evanston

(Note, that, as can be learned via: Northwestern University - Wikipedia, the free encyclopedia; Northwestern is considered to be one of the "top research universities in the United States".)

Abstract: The present invention relates to a process for the carbon dioxide reforming of methane (CH4) in the presence of a catalyst to produce a synthesis gas comprising hydrogen and carbon monoxide. The process utilizes a catalyst and reducing agent which under appropriate process conditions can accomplish the CO2 reforming of methane in the absence of steam. The process includes contacting methane and CO2 in the presence of an effective amount of rhodium incorporated into a natural or synthetic crystalline zeolite having a silicon to aluminum ratio of greater than or equal to about 1.0 under reforming conditions sufficient to convert CH4 to synthesis gas.

(Concerning the specified "crystalline zeolite" catalyst, we remind you that zeolites are well-known for their utility in hydrocarbon conversion processes, being for instance, key to the technology explained in:

West Virginia Coal Association | ExxonMobil Coal to Methanol to Gasoline | Research & Development; concerning both:

"United States Patent 4,348,486 - Production of Methanol via Catalytic Coal Gasification; Assignee: Exxon Research and Engineering Company; Abstract: Methanol is produced by gasifying a carbonaceous feed material with steam ... to produce a ... gas containing primarily carbon monoxide and hydrogen; (and) passing the gas stream ... to a methanol synthesis reactor ... to form methanol; (and) wherein said carbonaceous feed material comprises coal"; and:

"United States Patent 4,035,430 - Conversion of Methanol to Gasoline; Assignee: Mobil Oil Corporation; Abstract: The conversion of methanol to gasoline ... by a special class of crystalline zeolite".

And, it seems pertinent to include a note about "zeolite"s, in case you're unfamiliar with them. They are a common class of minerals of wide occurrence. As can be learned via:

Zeolite - Wikipedia, the free encyclopedia; "Zeolites are widely used in industry for water purification, as catalysts, for the preparation of advanced materials and in nuclear reprocessing. Their biggest use is in the production of laundry detergents. They are also used in medicine and in agriculture."

And, if we can't mine the ones we want, the technology does exist to synthesize them on a commercial, industrial basis.

Further, the required "Rhodium" is a precious metal; but, only a very small amount is needed to be spread out on the surface of the Zeolite; and, our good friends in Canada are able to mine plenty of it; so much so that Rhodium is used as one of the primary components in automotive exhaust catalytic converters, which should give you some idea of how available, and how economical to use, it is.

More can be learned via: Rhodium - Wikipedia, the free encyclopedia.)

Claims: A process for CO2 reforming of methane to produce a synthesis gas which comprises the steps of: 

(a) contacting methane and CO2 in the presence of an effective amount of rhodium incorporated onto a zeolite under conditions of temperature, pressure, and contact time to yield a product mixture comprising methane, CO2, carbon monoxide and hydrogen; and 

(b) separating the product mixture to recover the synthesis gas.

(The Methane and CO2 still in the "product mixture" are simply recycled back through the process, with additional, fresh, CO2 and Methane, after the "carbon monoxide and hydrogen" have been recovered.)

The process ... wherein said contacting step is carried out at a temperature between 400 C and 900 C. 

The process ... wherein said contacting step is carried out at a pressure of from about 1 Atmosphere to about 10 Atmospheres.

(Even if we have to go up to "10 Atmospheres", that's only 150 pounds per square inch; which, in terms of industrial processing, isn't that much. Power plant steam at 150 psi would be considered to be in the "medium" range of pressure. Temperatures "between 400 C and 900 C" could be attained, in part, by extracting waste heat from Coal-fired power plant exhaust, which, as can be learned in:

http://www.netl.doe.gov/technologies/coalpower/ewr/water/pdfs/EP%20Final%20Report.pdf; "Energy Penalty Analysis of Possible Cooling Water Intake Structure Requirements on Existing Coal-Fired Power Plants; U.S. Department of Energy; 2002";

exits the steam generation process at, generally speaking, about 315 C; and, which could be used to at least preheat the CO2 and the Methane, and bring them part way to the needed temperatures.)

The process ... wherein said contacting step is carried out in the presence of a zeolite loaded with from 0.1% to 7% rhodium.

(The "7% rhodium" could add up to quite a lot of money. The "0.1%" is another matter, though, since, by comparison and analogy, automotive catalytic converters, if we read the literature correctly, are loaded with about 0.35% Rhodium; and, we make a lot of such converters that our economy seems okay with.) 

The process ... wherein the recovered synthesis gas has a hydrogen to carbon monoxide ratio of about 1.

(That is a fairly low "hydrogen to carbon monoxide ratio" "synthesis gas". As can be learned via:

Fischer–Tropsch process - Wikipedia, the free encyclopedia, the ideal ratio would be about 2.

However, as seen in our reports of:

Hydrogen from Wind Power | Research & Development; concerning: "United States Patent 7,329,099 - Wind Turbine and Energy Distribution System; 2008; Abstract: A new design of vertical axis wind turbine is disclosed ... . A wind electric system, wherein the apparatus ... is coupled to electrical generating means, and said electrical generating means is connected to an electrical load (and, which) electrical load comprises at least one electrolysis cell, said at least one electrolysis cell connected to an output stream of hydrogen gas and further connected to an input stream of water"; and:

USDOE Algae Make Hydrogen for Coal and CO2 Hydrogenation | Research & Development; concerning: "United States Patent 4,442,211 - Method for Producing Hydrogen and Oxygen by Use of Algae; 1984; Assignee: The United States of America; A method of producing H2 and O2 by use of algae and light"; and:

NASA Hydrogen from Water and Sunlight | Research & Development; concerning: "United States Patent 4,045,315 - Solar Photolysis of Water; 1977; NASA; H2 is produced by the solar photolysis of water"; and:

West Virginia Coal Association | Germany & Pennsylvania Hydrogen from Hydropower | Research & Development; concerning: "United States Patent 6,864,596 - Hydrogen Production from Hydro Power; Voith Siemens Hydropower Generation GmbH and Incorporated, Germany and York, PA; A turbine installation configured for large scale hydrogen production includes a foundation structure separating an upper elevation headwater from a lower elevation tailwater (and, a) generator (and, an) electrolyzer ... producing hydrogen";

the need for supplemental Hydrogen should in no way be seen as a technical or economic barrier to the implementation of this CO2 recycling process, if liquid hydrocarbon synthesis is the desired end use of the synthesis gas produced by it.)

Description and Background: This invention relates to a process for producing synthesis gas by the carbon dioxide reforming of methane in the presence of a catalyst. 

Production of synthesis gas or syngas (mixtures comprising hydrogen and carbon monoxide) is an important first process step in the manufacture of numerous chemicals including ammonia and methanol.

(Syngas) to be used in the production of methanol ... requires lower H2 /CO ratios ...

A syngas having a SN (less than) 2 ("Stoichiometric Number", i.e., the "H2 /CO ratios") leads to undesirable byproducts in the production of methanol (e.g., higher alcohols).

(Note, however, that "higher alcohols" might not be that bad a product to have, along with the Methanol. Such "higher alcohols" could well include those more akin to typical liquid hydrocarbon fuels; or, those which could better serve as raw materials in the manufacturing of various plastics, wherein the Carbon Dioxide consumed in the production of the synthesis gas would be, in essence, permanently and, more importantly, productively sequestered.)

(Lower) H2 /CO ratio syngas mixtures desirable for methanol production can be achieved by replacing steam in (Methane reforming reactions) with carbon dioxide: 

With regard to CO2 -reforming of methane without steam, this reaction was first studied by Fischer and Tropsch in 1928 using nickel and cobalt based catalysts. This reaction was later commercialized as the Calcor process for which rhodium over amorphous oxide supports is one of the most effective catalysts.

(See: http://www.caloric.com/upload/Products/Caloric_CO2Reforming.pdf; and:

Calcor cleans up carbon monoxide production | Archive | Process Engineering; "Carbon monoxide is the feedstock for the production of many chemicals ... . To boost the purity of CO, the German company Caloric, of Munich, has developed the Calcor process - a reforming process combined with CO2 recovery and CO purification. The raw material, natural or liquid petroleum gas, is mixed with hydrogen, heated prior to catalytic/adsorptive hydration and desulphurisation, then mixed with CO2. While passing over the catalyst in the reformer tubes, the mixture of CO2 and feedstock is converted into a synthesis gas comprising CO, H2, CO2 and CH4. Heat for this endothermic reaction is generated by a high-velocity burner".

Also, keep in mind the reason "Fischer and Tropsch" studied these reactions, as indicated in:

http://www.afdc.energy.gov/afdc/pdfs/epa_fischer.pdf; concerning: "Clean Alternative Fuels: Fischer-Tropsch;

United States Environmental Protection Agency; Transportation and Air Quality Transportation and Regional Programs Division; EPA420-F-00-036; 2002; Fischer-Tropsch technology converts coal ... into a high-value, clean-burning fuel. The resultant fuel is colorless, odorless, and low in toxicity".)

Summary: The present invention relates to a process for the carbon dioxide reforming of methane in the presence of a catalyst to produce a synthesis gas comprising hydrogen and carbon monoxide. 

The process comprises contacting methane and CO2 in the presence of an effective amount of rhodium incorporated onto a natural or synthetic crystalline zeolite having a silicon to aluminum ratio (as specified)

under reforming conditions sufficient to produce a product mixture comprising hydrogen, carbon monoxide, methane and CO2. The product mixture is separated to recover the synthesis gas. Optionally, the product mixture which contains unreacted reactants can be recycled for further reaction."

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And, again, as seen in our report of:

Chicago Recycles CO2 to Methane | Research & Development | News; 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 ... . If desired, solar energy can be utilized to provide the potential for the electrolyzing";

we can harness freely-available environmental energy to drive processes that make the Methane, needed for the process of our subject herein, "United States Patent 5,753,143 - Process for the Carbon Dioxide Reforming of Methane", "to produce a synthesis gas comprising hydrogen and carbon monoxide", out of, in addition to a little Water, nothing but Carbon Dioxide itself.


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