This will, we caution, be an extended and complicated dissertation; and, we beg your patience.
We refer you first to one of our fairly recent dispatches, concerning just one of our USDOE's projects directed towards the biological recycling of industrial effluent Carbon Dioxide.
As now accessible via:
USDOE Algae Recycle CO2 into Liquid Fuels | Research & Development; we made report of:
"Liquid Fuels from Microalgae; 1987; National Renewable Energy Laboratory (NREL), Golden, CO; USDOE; Abstract: The goal of the DOE/SERI Aquatic Species Program is to develop the technology to produce gasoline and diesel fuels from microalgae. The algae can be grown in large outdoor ponds, using the resources of sunlight ... and carbon dioxide (and) program activities include ... research on converting microalgae lipids into liquid fuels. (Algae) cells then are subjected to an extraction process to remove the lipids (from which we can) produce fuels similar to diesel fuels and ... gasoline. (The) cell residue after lipid extraction can be anaerobically digested for the production of methane and carbon dioxide."
Such blends of Methane and an amount of what we could consider to be "residual" Carbon Dioxide, that would be miniscule relative to the initial amount of CO2 fed to the bio-reactor, we pointed out, can, as we have separately documented many times, such as, more recently, in:
March, 2011, CO2-to-Methanol US Patent Awarded | Research & Development; concerning: "United States Patent 7,906,559 - Conversion of Carbon Dioxide to Methanol and/or Dimethyl Ether; 2011; University of Southern California; Abstract: The invention discloses a method of converting carbon dioxide to methanol and/or dimethyl ether using any methane source or natural gas consisting of a combination of steam and dry reforming ... with subsequent conversion of the CO and H2 mixture ... to methanol and/or dimethyl ether";
be reacted together, "reformed", into a synthesis gas, a "CO and H2 mixture", suitable for catalytic chemical condensation into liquid hydrocarbon fuels.
We note that such CO2-Methane reforming reactions can be conducted with or without the inclusion of varying amounts of Steam, H2O, in the reaction mix, to influence in desired ways the final composition of the resulting synthesis gas mixture of Carbon Monoxide and Hydrogen; and, to thus "adjust" the ratios of CO and H2, relative to each other, so that the syngas is suitable for the production of particular hydrocarbons.
However, such reactions between Carbon Dioxide, Methane, and Steam are endothermic; that is, like the related reactions between Coal and Steam to form Carbon Monoxide and Hydrogen syngas, which we have documented to the point of tedium, they require the application of heat in order to drive them forward.
Some innovative and sustainable ways have been developed for supplying that needed energy, as seen, for just one instance, in:
USDOE 1990 Solar CO2-Methane Recycling-Reforming | Research & Development; concerning the: "Solar Reforming of Methane; 1990; Sandia National Labs, NM (USDOE); Abstract: The concept of solar driven chemical reactions ... was successfully demonstrated. Solar reforming of methane (CH4) with carbon dioxide (CO2) was achieved".
The same is true of the reactions needed to produce synthesis gas from Coal, as well, as we've also documented, for just one example, in:
NASA Hydrogasifies Coal with Solar Power | Research & Development; wherein is reported: "United States Patent 4,290,779 - Solar Heated Fluidized Bed Gasification System; 1981; National Aeronautics and Space Administration; A solar-powered fluidized bed gasification system for gasifying carbonaceous material".
However, environmental energy isn't always available in the quantities needed in the places where it can best be employed, so exothermic chemical processes of oxidation are most often included in the designs of such reaction technologies, along with catalysts, to drive the needed endothermic reforming reactions.
Oxygen can be supplied directly, in controlled amounts, to the mix of reactants, to help to support any needed exothermic oxidation reactions; a techniques which, though successful and efficient, especially in terms of limiting most of the co-production of unwanted Nitrogen Oxides, does lead to the co-production, or, in the case of CO2-CH4 reforming reactions, of what might be thought of as the, essentially, "pass-through" of some Carbon Dioxide.
That is certainly true of early examples of the technology, as seen, for one instance, in:
1939 CO2 + CH4 = Hydrocarbons | Research & Development; concerning: "US Patent 2,180,672 - Process for Converting Gaseous Hydrocarbons; 1939; Phillips Petroleum; An object of the present invention is the production of hydrocarbons suitable for motor fuel ... from gaseous hydrocarbons of lower molecular weight (in which) carbon dioxide ... may be mixed directly with ... methane";
wherein a close read of the full Disclosure reveals that the reaction between Carbon Dioxide and Methane, to produce hydrocarbon synthesis gas, is to be driven forward by heating the reactant gases to a temperature between 250 and 450 degrees Centigrade, which, considering that the boiling point of Water is 100 C, is pretty danged hot.
Further, technologies such as that disclosed in the above USP 2,180,672 posit that the heat is to be supplied by a process of combustion external to the reaction process itself, with attendant inefficiencies in heat transfer which are obvious, and, the co-production of extraneous, and unutilized, Carbon Dioxide.
In order to limit the co-production, or pass-through, of Carbon Dioxide, especially when CO2 is used as one of the agents of gasification in Coal hydro-gasification processes, and when environmental energy isn't available, as it is in the process of NASA's "United States Patent 4,290,779", to drive the reactions forward, technologies have been developed which utilize substances capable of supplying Oxygen in restricted and controlled amounts to the needed exothermic oxidation reactions, so that more Carbon Monoxide is formed, and any co-production of Carbon Dioxide is limited and restricted.
Examples of such technology can be seen in our reports of:
Oklahoma Oxygen Donor Coal Gasification | Research & Development; which includes information about: "USP 4,070,160 - Gasification Process; 1978; Phillips Petroleum Company; Abstract: (A) process for gasifying solid carbon sources such as coal utilizing zinc oxide as the oxygen donor"; and:
Exxon Oxygen Donor Coal Gasification | Research & Development; about: "USP 4,309,198 - Converting Liquid and/or Solid Fuel to a Substantially Inerts-free Gas; 1982; Exxon Research and Engineering Company; Abstract: The invention relates to the conversion of fuel (solid and/or liquid) to reducing and/or synthesis gas by contacting the fuel in a fluidized conversion bed with a solid oxygen donor (e.g. CaSO4 - Calcium Sulfate) at a fuel conversion temperature ... in the presence of at least one gas/vapor phase substance such as H2 and/or H2O and/or CO and/or CO2".
And, herein, we see that a technology very similar to those established, as above, by Phillips and Exxon, for supplying limited amounts of Oxygen to a Coal hydrogasification process, in order to produce a synthesis gas suitable for the production of hydrocarbons, can, as well, be applied to Carbon Dioxide and Methane reforming processes, especially, we submit, to the blends of CO2 and CH4 as might be generated by a biological processing unit, as in the above-noted "Liquid Fuels from Microalgae", which digests residual botanical wastes resulting, in the first place, from a process that productively recycles, into liquid hydrocarbon fuels, a far larger initial amount of Carbon Dioxide.
Comment follows, and is inserted within, our excerpts from the initial link in this dispatch to:
"United States Patent 7,951,350 - Fuel Gas Reforming Systems and Methods
Date: May 31, 2011
Inventor: Donald Taylor, CA
Assignee: West Biofuels, LLC, San Rafael
(Note: "West Biofuels", according to their web site, "is a leading-edge energy company that has developed a superior reforming technology providing a clean, sustainable and environmentally friendly energy from biomass. We see the stored energy in waste materials all around us and know it can play a vital role in that independence. The time has come to empower our people, our economy and the vast energy resource that is biomass.")
Abstract: A process and system for producing an effluent gas containing carbon monoxide and hydrogen is presented. The process includes introducing a fuel gas including a hydrocarbon and a reformer gas into a reactor system. The reformer gas may include steam, CO2, or a mixture thereof. Under steam reforming temperatures and pressures, the gases are reacted in the presence of reactant solids. The reaction process produces a carbon monoxide and hydrogen containing effluent, which may be withdrawn from the reactor system.
(Note, yet again, that, as above, Carbon Dioxide itself may be used as one of the agents of gasification for carbonaceous material, no matter what the origin of that carbonaceous material.)
Claims: A process for producing carbon monoxide and hydrogen containing effluent gas, (which comprises) introducing a fuel gas and a reformer gas into a reactor system, said fuel gas including a hydrocarbon, and said reformer gas including at least one of steam or CO2; (and) reacting the fuel gas and the reformer gas with a reactant solids under steam reforming temperatures and pressures to produce a carbon monoxide and hydrogen containing effluent and a spent solids.
(And) wherein the hydrocarbon comprises ... methane (and/or others).
(And) wherein a mass ratio of steam and CO2 to hydrocarbon is from about 0.1 to about 4.0.
(Quite a lot of Carbon Dioxide, relative to Methane, can be used, it seems. There might exist the potential to add CO2 from an outside source to the blend of CO2 and Methane formed initially from the biomass.)
The process ... wherein the step of reacting occurs under partial oxidation conditions of the reactant solids.
The process ... further including heat carrier particulates in the reactor system.
The process ... wherein the reactant solids are dispersed in the heat carrier.
The process ... further comprising preheating the heat carrier particulates with a hot flue gas.
(Anyone know where we might find some "hot flue gas" in US Coal Country?)
The process ... wherein the heat carrier particulates are ceramic solids.
The process ... further comprising regenerating the spent solids to form regenerated reactant solids and recycling the regenerated reactant solids for reaction with the fuel gas and reformer gas.
The process ... wherein the reactant solids are finely divided metal or metal oxide reactants ... selected from the group consisting of calcium, calcium oxide, iron, iron oxide, and combinations thereof.
(We must interrupt to note, that, in our reports of:
Consol 1953 Coal to Hydrogen & Methane with No CO2 | Research & Development; concerning: "United States Patent 2,654,663 - Gasification of Carbonaceous Solid Fuels; 1953; Consolidation Coal Company; Abstract: This invention relates to the gasification of carbonaceous solid fuels, and particularly to the production of hydrogen (and) methane (wherein) the gaseous products are substantially free of carbon dioxide"; and:
Consol 1954 Coal Steam Gasification | Research & Development; which makes report of: "United States Patent 2,682,455 - Gasification of Carbonaceous Solid Fuels; 1954; Consolidation Coal Company; Abstract: This invention relates to the gasification of carbonaceous solid fuels and, more particularly, to methods of and apparatus for reacting carbonaceous solid fuels with steam";
Consol specifies the use of Calcium Oxide as the Oxygen donor for Coal gasification, but notes in broader discussion, as does our subject, United States Patent 7,951,350, relative to CO2-CH4 reforming, that other metal oxides, too, can be so utilized as "reactant" Oxygen-donating "solids", with Consol including those of the Iron Group, as well as Magnesium and Strontium.)
Description and Background: The steam reforming of ... methane ... is most often accomplished in externally heated tubes which contain catalyst. The product of such process is a synthesis gas composed primarily of H2 and CO. This type of process is known in the art, and is regularly practiced at industrial scale. In general, a hydrocarbon and steam mixture in the proper proportion is introduced into a reformer furnace, containing a plurality of parallel tubes packed with a suitable reforming catalyst. The tubes are externally heated to provide the endothermic heat of reaction for the reforming process, with the reaction generally being effected at a temperature above 1600 degrees F.
The above process has numerous limitations, especially that of effecting economic heat transfer through the tubes at the high temperatures and high heat fluxes employed in the steam reforming process. For example, in order to withstand the high temperatures used in steam reforming, expensive heat resistant alloys must be used in constructing the furnace, thereby raising capital costs. Moreover, carbon deposition on the catalyst necessitates the use of excess amounts of steam in the hydrocarbon and steam mixture, which serves to decrease the net conversion efficiency and results in a high ratio of H2 to CO in the synthesis gas product when a 1:1 ratio is optimum for synthesis of some high-value products, including the production of mixed-alcohols.
Furthermore, when CO2 is present in the hydrocarbon and steam mixture and CO2 is intended to participate in the reforming reactions, the deposition of carbon on the catalyst becomes more problematic and the catalyst is thereby deactivated.
Therefore, it would be advantageous to develop an improved process for reforming of hydrocarbons.
As such, it would be desirable to provide processes and systems which allow for improved steam reforming. Additionally, it would be desirable to provide processes and systems which allow for reduced cost materials.
Summary: (The) present invention (is) a process for producing carbon monoxide and hydrogen containing effluent (from) fuel gas and a reformer gas ... .
The reformer gas may include steam, CO2, or a mixture of the two. The fuel gas and reformer gas are reacted with reactant solids under steam reforming temperatures and pressures to produce a carbon monoxide and hydrogen containing effluent and spent solids. The effluent can then be withdrawn from the reactor system.
In one embodiment, heat carrier particulates can be present in the reactor system. The heat carrier particulates can be inert, and may also have reactant solids dispersed therein.
(We'll interrupt here to point out one key fact. Although "reactant solids" are included, to provide Oxygen for limited and controlled exothermic oxidation reactions, which provide heat energy to help drive the Carbon Dioxide-Methane-H2O reforming reactions, some considerable extra heat energy input is required; thus, the need for "heat carrier particulates". As we will summarize in concluding comments, West Biofuels does explain how those "particulates" can be heated, in a process integrated, in part, into the total system.)
The spent solids of the process can be regenerated to form reactant solids which may be recycled and used as reactant solids for reaction with the fuel mixture and reformer gas.
(The) reforming of hydrocarbons to produce a synthesis gas can be readily accomplished with improved heat transfer and use of low-cost particulate reactant solids.
Finely divided reactant solids can be relatively low-cost materials ... . For example, pulverized iron ore or calcium in the form of limestone, or a mixture iron and calcium, and the like, are examples of reactants used in the process to enhance the reforming of hydrocarbons by reacting with carbon and hydrocarbons, and can be substantially regenerated in a solids heater by contacting with combustion exhaust gases that provide a thermo-chemical environment with medium to low oxidation potential, such that carbon deposits may be removed via oxidization and the metal and alkali reactants are partially oxidized ... .
(Again, as in the other, similar technologies we've documented, the Oxygen donors can be regenerated in an integral step in the process. In other, related, technologies, wherein more reactive metals, such as Zinc, are utilized, the Oxygen donor can be regenerated by reacting the reduced metal with Water, H2O, in a decomposition process which coincidentally generates extra Hydrogen that can be added to the blend of product synthesis gas. More reports concerning those potentials, especially as they relate to CO2-CH4 reforming, are in process, but for an introduction to them, see:
Japan Uses Zinc to Liquefy Coal | Research & Development; concerning, in part: "Coal liquefaction by in-situ hydrogen generation.: Zinc-water-coal reaction;
Hokkaido University, Japan".)
As used herein, "reactant solids" refer to solid, substantially insoluble materials which chemically react with the mixture to form a distinct material, e.g. spent solids, which is different from the starting material. Typically, the reactant solids are metals and/or metal oxides such as, but not limited to iron, iron oxide, aluminum, aluminum oxide, alkali metals, and compounds incorporating such elements.
In one embodiment of the present invention ... both steam and carbon dioxide are the primary components in the reformer gas.
As used herein, "hydrocarbon" refers to generally ... methane.
(Keep in mind, that, as seen for just one example in:
Chicago Recycles CO2 to Methane | Research & Development; concerning the; "United States Patent 4,609,440 - Electrochemical Synthesis of Methane; 1986; Gas Research Institute, Chicago; Abstract: A method is described for electrochemically reducing carbon dioxide to form methane";
a number of technologies exist which would enable us to manufacture any needed extra Methane from Carbon Dioxide itself.)
The terms "heat carrier," "heat-carrier," and "heat carrier particulates" are used interchangeably and refer to solid particulates that effectively transfer heat from a pre-heating area to the reformer-reactor. Such heat carrier particulates can be inert to the materials used in the present invention, and ... can include, but are not limited to, such materials as alumina beads, titania beads, zirconia beads, and combinations thereof."
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We must note that, especially since the full Disclosure suggests the use of flue gas from combustion processes to bring the "heat carrier particulates" up to reaction temperature, and to help to reactivate the "reactant solids", flue gas perhaps obtained from an unrelated industrial process, that some Carbon Dioxide results from the overall operation of the system, but in quantities less than that consumed by it.
It is suggested by the Inventor that any such residual CO2 be fed to Algae, which would, in the course of producing bio-lipids which are convertible into liquid hydrocarbons, also, as in our introductory citation of "Liquid Fuels from Microalgae; 1987; USDOE; Abstract: The goal of the DOE/SERI Aquatic Species Program is to develop the technology to produce gasoline and diesel fuels from microalgae"; produce residual biomass, which, whereas the USDOE envisions using microorganisms to convert that residual biomass into Methane and Carbon Dioxide, the Inventor herein submits could be added to an original mix of organic materials for gasification reactions targeted on the co-production of CO2 and CH4.
As a further refinement, though not reflected in our excerpts, the full Disclosure of our subject, "United States Patent 7,951,350", does discuss, as do others similar, regarding what is, in essence, a process of "tri-reforming", as exemplified by the multiple reports we've made concerning such technology as it has been further developed by the petroleum industry, as seen somewhat more recently in:
Exxon 2010 CO2 + Methane = Liquid Hydrocarbons | Research & Development; concerning: "United States Patent 7,772,447 - Production of Liquid Hydrocarbons from Methane; 2010; ExxonMobil;
the ratios of the CO2, CH4 and H2O in initial mix of reactants can be adjusted so as to result in the generation of a synthesis gas suited for catalytic condensation into specific products, which the Inventor, through suggestions, obviously prefers to be alcohols, but, which, as in the above-cited Exxon "United States Patent 7,772,447", could as well be "higher hydrocarbons".
And, considering that it could all start with Carbon Dioxide-recycling biomass, perhaps coupled with a little extra Methane made, as in, for one example, the above-cited process of " "United States Patent 4,609,440", from Carbon Dioxide, we have herein again more testament to the plain fact that Carbon Dioxide, as it arises in only a small way, relative to natural and uncontrollable sources of emission, such as volcanoes, from our varied and productive uses of Coal, is a valuable raw material resource.
We can, again as herein, utilize CO2 both indirectly, through biomass, and directly, through reforming reactions into and then with Methane, to generate a synthesis gas composed of variable amounts of Hydrogen and Carbon Monoxide, and suitable for catalytic processing into a wide range of "high-value products, including", as herein, "mixed-alcohols" and, according, as above, to ExxonMobil, "higher hydrocarbons".