Paul Sabatier, of France, as we've documented several times, demonstrated more than one century ago that we can synthesize - with, as Sabatier himself put it in his 1912 Nobel Prize acceptance speech, "the greatest ease" - substitute natural gas Methane by using, as the key raw material, Carbon Dioxide.
Over certain metal catalysts - - Sabatier employed nickel, but some other metals will work as well, and perhaps even better - - Carbon Dioxide, as recovered from whatever handy source, will react with elemental, molecular Hydrogen to yield Methane and water.
As we learned in:
West Virginia Coal Association | NASA Hydrogen from Water and Sunlight | Research & Development; concerning: "United States Patent 4,045,315 - Solar Photolysis of Water; 1977; Inventors: James Fletcher (pro-forma, we believe), Administrator, NASA; and, Porter R. Ryason; Abstract: Hydrogen is produced by the solar photolysis of water in a first photo-oxidation vessel with a transparent wall in the presence of a water soluble photo-oxidizable reagent and an insoluble hydrogen recombination catalyst. Simultaneously oxygen is produced in a second photo-reduction reactor with a transparent wall in the presence of an insoluble photo-reduction reagent catalyst";
our National Aeronautics and Space Administration, NASA, quite some time ago developed technology for extracting such elemental Hydrogen, H2, from the abundant water, H2O, molecule, in a process powered only by all-natural and freely-available sunlight.
And, quite recently, as seen in:
NASA 2014 CO2 to Methane | Research & Development | News; concerning: "United States Patent 8,710,106 - Sabatier Process and Apparatus for Controlling Exothermic Reaction; April 29, 2014; Assignee: Precision Combustion, Inc., CT; Abstract: A Sabatier process involving contacting carbon dioxide and hydrogen in a first reaction zone with a first catalyst bed at a temperature greater than a first designated temperature; feeding the effluent from the first reaction zone into a second reaction zone, and contacting the effluent with a second catalyst bed at a temperature equal to or less than a second designated temperature, so as to produce a product stream comprising water and methane. The first and second catalyst beds each individually comprise an ultra-short-channel-length metal substrate. An apparatus for controlling temperature in an exothermic reaction, such as the Sabatier reaction, is disclosed. Government Support: This invention was made with support from the U.S. government under U.S. Contract No. NNX10CF25P sponsored by the National Aeronautics and Space Administration. The U.S. Government holds certain rights in this invention";
we learned that NASA and their contractors had revisited the Sabatier process, perhaps in light of the fact that Hydrogen can be so efficiently extracted from water using solar energy, and designed an improved Sabatier CO2-to-Methane reactor, one which enables the harvesting of some of the heat energy generated by the exothermic Methane synthesis reaction. Such "cooling" makes the Sabatier reaction itself more efficient, and could perhaps make the extracted thermal energy available to help drive other functions needed in the overall CO2-to-Methane process.
And, herein we learn that NASA and their contractors have gone on to advance even further their Sabatier technology, improving, tweaking just a bit and making more efficient, the CO2-to-substitute natural gas Methane Sabatier reaction, by designing the reactor itself in such a way that, in addition to extracting heat from the reactor so that more Methane is synthesized, the reaction proceeds in stages and the temperature throughout the reaction zone, or zones, is thus maintained at a steadier, more optimum level.
Comment follows and is inserted within excerpts from the initial link in this dispatch to:
"United States Patent Application 20140178270 - Sabatier Process and Apparatus for Controlling Exothermic Reaction
Date: June 26, 2014
Inventors: Christian Junaedi, et. al., CT
Assignee: Precision Combustion, Inc., Hartford, CT
Abstract: A Sabatier process involving contacting carbon dioxide and hydrogen in a first reaction zone with a first catalyst bed at a temperature greater than a first designated temperature; feeding the effluent from the first reaction zone into a second reaction zone, and contacting the effluent with a second catalyst bed at a temperature equal to or less than a second designated temperature, so as to produce a product stream comprising water and methane. The first and second catalyst beds each individually comprise an ultra-short-channel-length metal substrate. An apparatus for controlling temperature in an exothermic reaction, such as the Sabatier reaction, is disclosed.
Government Interests: This invention was made with support from the U.S. government under U.S. Contract No. NNX10CF25P sponsored by the National Aeronautics and Space Administration. The U.S. Government holds certain rights in this invention.
Claims: An apparatus for use in an exothermic reaction, the apparatus comprising:
(a) a first reaction zone comprising a first catalyst bed comprising at least one layer of ultra-short-channel-length metal substrate;
(b) a second reaction zone in fluid communication with and downstream from said first reaction zone, the second reaction zone comprising a second catalyst bed comprising at least one layer of ultra-short-channel-length metal substrate;
(c) at least one inlet for feeding one or more reactants into the first reaction zone;
(d) an outlet for exiting a product stream from said second reaction zone;
(e) a means for removing heat from said first reaction zone so as to maintain a temperature in said first reaction zone less than a maximum temperature suitable for materials of construction but greater than a first designated temperature; and:
(f) a means for removing heat from said second reaction zone so as to maintain a temperature in said second reaction zone equal to or less than a second designated temperature.
An apparatus for use in an exothermic process, comprising:
(a) two concentric tubes, such that an inner tube of a specified diameter is positioned within an outer tube of a larger diameter; the outer tube comprising a housing; the inner tube comprising a reactor section; and the annular space bounded by the inner tube and the outer tube comprising a heat exchange section;
(b) the reactor section comprising a first catalyst bed, and a second catalyst bed downstream and in fluid communication with the first catalyst bed; the first and second catalyst beds each individually comprising at least one layer of ultra-short-channel-length metal mesh substrate having one or more Group VIII metals deposited thereon;
(c) at least one inlet for feeding one or more reactants into the first catalyst bed;
(d) an outlet for removing a product stream from the second catalyst bed;
(e) at least one inlet for feeding a heat exchange fluid into the annular space between the inner tube and the outer tube, the inlet being coincident with the second catalyst bed; and:
(f) at least one outlet for removing the heat exchange fluid from the annular space between the inner tube and the outer tube, the outlet being coincident with the first catalyst bed.
The apparatus ... wherein the ultra-short-channel-length metal substrate is selected from the group consisting of stainless steel, iron-based alloys, and nichrome alloy (and) wherein either or both of the first and second catalyst beds comprises a plurality of metal mesh sheets ranging in number from 2 to 300 metal mesh sheets (and/or) wherein either one or both of the first and second catalyst beds comprises one metal mesh sheet rolled into a coiled configuration.
The apparatus ... wherein the ultra-short-channel-length metal substrate of the first and second catalyst beds has a channel length ranging from 25 microns to 500 microns (and) wherein the Group VIII metal comprises iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, or a combination thereof (and) wherein the Group VIII metal is supported on a support selected from the group consisting of titania, silica, magnesia, alumina, zirconia, and mixtures thereof.
The apparatus ... wherein loading of the Group VIII metal on the ultra-short-channel-length metal substrate ranges from 7.6 to 22.9 milligrams per square centimeter (and) wherein the ultra-short-channel-length metal substrate comprises a plurality of void volumes in random order.
Background and Field: In one aspect, this invention pertains to a process of converting a mixture of carbon dioxide and hydrogen into a product mixture comprising water and methane (hereinafter "the process"). In the art the process is known as the "Sabatier process" or the "Sabatier reaction" or the "carbon dioxide methanation reaction." In another aspect, this invention pertains to an apparatus that finds use as a reactor for an exothermic process, for example, the Sabatier reaction.
Currently, oxygen generators onboard the International Space Station produce oxygen by means of the electrolysis of water. Hydrogen, produced as a co-product of the electrolysis, is discarded overboard. Accordingly, large quantities of water are required to be transported to the Space Station, not only for the production of oxygen, but also for human consumption and other purposes, including hygiene. For long duration space missions at the Space Station or beyond low Earth orbit, the transportation of large amounts of water from Earth into space is prohibitive. Accordingly, water needed for the production of oxygen and other purposes must be supplied by a method other than transportation from Earth.
As astronauts consume oxygen through respiration, carbon dioxide is produced, which must be removed from the atmosphere within the Space Station or spacecraft designed for longer missions beyond Earth orbit.
Clearly it would be beneficial to find a method of utilizing the carbon dioxide to produce life support consumables onboard of a spacecraft instead of venting the carbon dioxide overboard. Likewise, it would be beneficial to find a method for removing or utilizing carbon dioxide in extraterrestrial atmospheres that contain large quantities of carbon dioxide, for example, the Martian atmosphere.
Current interest is centered on the Sabatier reaction for in-situ resource utilization of carbon dioxide and for production of required human consumables ... .
(Well, according to some opposed to our use of Coal in the generation of abundant, affordable and reliable electric power, we have, right here on Earth, certain "atmospheres that contain large quantities of carbon dioxide", and, we don't, here on Earth, have to worry about "the transportation of large amounts of water". We have plenty of it in our oceans and major rivers, which, as seen again and separately in:
More NASA Hydrogen from Water and Sunlight | Research & Development | News; concerning: "United States Patent 4,051,005 - Photolytic Production of Hydrogen; 1977; Assignee: United Technologies Corporation, Hartford (CT); Government Interests: The invention described herein was made in the course of a contract with the National Aeronautics and Space Administration. Abstract: Hydrogen and oxygen are produced from water in a process involving the photo-dissociation of molecular bromine with radiant energy at wavelengths within the visible light region";
we can use, in a process employing only light energy, as in the earlier-cited "US Patent 4,045,315 - Solar Photolysis of Water; 1977; NASA, as a source of the needed elemental, molecular Hydrogen.)
The Sabatier reaction specifically converts a mixture of carbon dioxide and hydrogen in the presence of a catalyst into a mixture of water and methane.
The reaction accomplishes a primary goal of converting carbon dioxide, built-up in a space capsule or ubiquitous to an extraterrestrial environment, into valuable human consumables ... .
(NASA is most interested in the water product of the Sabatier reaction, but substitute natural gas Methane, here on Earth, is another valued "human consumable".)
Methane resulting as a coproduct of the Sabatier reaction could be utilized advantageously as a propellant for a return voyage to Earth.
The chemical equation for the Sabatier reaction for converting carbon dioxide and hydrogen into water and methane is:
CO2 + 4H2 = 2H2O + CH4 (Methane)
The chemical equation representing the electrolysis of water to produce oxygen and hydrogen is:
2H2O = 2H2 + O2
(Granted, a lot of Hydrogen is needed to effect the transmutation of CO2 into Methane. But, half the water used is regenerated in the Sabatier CO2-to-Methane reaction, and the remainder would be reconstituted when the Methane product of the Sabatier reaction was combusted. And, although it would take a fair amount of energy to extract the Hydrogen from the water, that energy, as in United States Patents 4,051,005 and 4,045,315, as cited above, can be supplied by freely-available and, in essence, eternal sunlight. The water and the Hydrogen could thus be seen as facilitators, cycled without being permanently consumed, for the use of solar energy in the production of hydrocarbon fuels from Carbon Dioxide. As it happens, as will be discussed, but only briefly, further on, the product Methane can also be used and consumed in the synthesis of higher hydrocarbons, including non-fuel hydrocarbons also currently derived from natural petroleum, and in which non-fuel hydrocarbons made from Methane as a raw material the CO2 carbon consumed in the Sabatier synthesis of the Methane would remain productively, chemically and permanently, "sequestered".)
Summary: In one aspect, this invention pertains to a novel two-stage Sabatier process of converting carbon dioxide into a mixture of water and methane.
The novel Sabatier process comprises: (a) contacting a mixture of carbon dioxide and hydrogen in a first reaction zone in the presence of a first catalyst bed comprising at least one layer of ultra-short-channel-length metal substrate, the contacting occurring at a temperature greater than a first designated temperature, so as to produce an effluent comprising water and methane and unconverted carbon dioxide and hydrogen; and (b) contacting the effluent from step (a) in a second reaction zone with a second catalyst bed comprising at least one layer of ultra-short-channel-length metal substrate, the contacting occurring at a temperature equal to or less than a second designated temperature, so as to produce a product comprising water and methane with a carbon dioxide conversion greater than about 80 percent of an equilibrium carbon dioxide conversion under isothermal process conditions.
(The "isothermal" means that they are, through the design of the reactor, maintaining basically one steady temperature throughout separate but connected reaction zones, in a way similar, or at least related, to another hydrocarbon synthesis technical design seen in our report of:
Bayer Improves Fischer-Tropsch Hydrocarbon Synthesis | Research & Development | News; concerning: "United States Patent 8,557,880 - Multi-stage Adiabatic Method for Performing the Fischer-Tropsch Synthesis; 2013; Assignee: Bayer Intellectual Property GmbH, Germany; Abstract: The present invention relates to a multistage adiabatic process for performing the Fischer-Tropsch synthesis at low temperatures, in which the synthesis is performed in 5 to 40 series-connected reaction zones under adiabatic conditions. (A process) for preparing liquid hydrocarbons from the process gases carbon monoxide and hydrogen";
wherein a blend of "carbon monoxide and hydrogen", as we might obtain by the gasification of Coal, is catalytically, chemically condensed into, primarily, liquid hydrocarbons "under adiabatic conditions". The word "adiabatic" means that no heat needs to be added to or extracted from the system, although, strictly speaking, that isn't exactly true of the NASA CO2-to-Methane process herein, since a close read of the full Disclosure reveals, that, if desired, heat exchange for the exhaust gases of the two connected reaction zones can be arranged.)
For the purposes of this invention, the term "carbon dioxide conversion" is defined as the moles of carbon dioxide changed to products in the overall two-stage process divided by the moles of carbon dioxide fed to the first reaction zone, on a percentage basis. The words "an equilibrium carbon dioxide conversion under isothermal process conditions" refers to the carbon dioxide conversion that is theoretically achievable at equilibrium, as calculated for an isothermal Sabatier process at a specified temperature, pressure, and inlet H2/CO2 mole ratio. The word "isothermal" refers to a process being operated and maintained at essentially one specified temperature at all points in the reaction section.
More advantageously, use of the ultra-short-channel-length metal substrate provides for improved heat and mass transfer, which lead to improved carbon dioxide conversion and improved yields of water and methane. Even more advantageously, when using the temperature control described herein, the process of this invention, in preferred embodiments, achieves a near-equilibrium CO2 conversion, that is, about 97 percent of the equilibrium CO2 conversion at isothermal process conditions.
(In point of fact, the above "97 percent", although we used it in our title because, honestly, it sounded pretty good, doesn't necessarily mean that a full 97 percent of the CO2 is being converted, but, somewhat generally speaking, 97 percent of the theoretical maximum of CO2 conversion is taking place. That, at least, is as the wording was explained to us by someone we think understands the concepts involved. The full Disclosure presents a more complete discussion of the details, which are really beyond our scope herein. The gist, though, is that most, more than half, of the CO2 is being used and consumed in the synthesis of Methane, if not quite all of it; and, this is still an efficient process as industrial processes go.)
The ultra-short-channel-length catalysts used in the process of this invention operate at acceptably uniform temperatures close to the temperature of the reacting gasses. In contrast, catalysts of the prior art, such as pelleted beds or microchannel ceramic foams, are prone disadvantageously to hot spots that lead to catalyst degradation. For example, after 100 hours of operation, the CO2 conversion demonstrated by the prior art catalyst supported on metal felt in a microchannel reactor is reduced from an initial value of approximately 70 percent to approximately 62 percent. In contrast, the catalyst in the process of this invention has been run for a similar duration at essentially equilibrium CO2 conversion and essentially without indication of catalyst degradation.
In addition, the catalyst bed used in the process of this invention, comprising the ultra-short-channel-length metal substrate, is more compact and weighs appreciably less than prior art pelleted catalyst beds and prior art ceramic microchannel foam or metal catalysts. Thus, the process of this invention advantageously results in smaller launch payloads and lower launch costs. Moreover, the catalyst comprising the ultra-short-channel-length metal substrate of this invention exhibits improved mechanical durability, as compared with pelleted catalysts. One method of measuring mechanical durability involves weighing fines produced when the catalyst is exposed to vibrational stress. Mechanical durability is important where the catalyst is expected to withstand significant vibrational load, such as during launch into space.
(It) is possible to integrate the Sabatier process of this invention with a gas-to-liquid (GTL) conversion process to convert methane to methanol".
Our final excerpted passage, as immediately above, seems a good place to close, since the contracted inventors of this NASA CO2-to-Methane technology specify that the Methane, as made herein from Carbon Dioxide via the process which won its original inventor, Paul Sabatier, a Nobel Prize in Chemistry, can be converted into fuel alcohol "methanol".
And, another winner of the Nobel Prize in Chemistry, George Olah, at the University of Southern California, explained how, in our report of:
California 2013 CO2 + Methane = Methanol | Research & Development | News; concerning: "United States Patent 8,440,729 - Conversion of CO2 to Methanol Using Bi-Reforming of Methane; 2013; Inventors: George Olah and G.K. Surya Prakash, CA; Assignee: University of Southern California, Los Angeles; Abstract: The invention provides for a method of forming methanol by combining a mixture of methane, water and carbon dioxide under specific reaction conditions sufficient to form a mixture of hydrogen and carbon monoxide which are then reacted under conditions sufficient to form methanol";
Methanol can be formed from the Methane made, via the process of our subject herein, "United States Patent Application 20140178270 - Sabatier Process and Apparatus for Controlling Exothermic Reaction", from Carbon Dioxide, by, in essence, reacting that CO2-based Methane with even more Carbon Dioxide.
And, clearly, by including the stipulation that Methane made from Carbon Dioxide can be used to synthesize fuel alcohol Methanol, which can itself be used to synthesize useful more stuff like gasoline and plastics, NASA and it's contracted scientists are telegraphing the fact that this technology would have far broader application than just converting "carbon dioxide, built-up in a space capsule ... into valuable consumables". The implication we take from it is that we can, as well, efficiently convert CO2 into Methane on an industrial scale, a scale meaningful for use on the surface of this big spaceship we call Earth.