As we documented in our report of:
USDOE 2013 CO2-Free Coal to Liquid Hydrocarbons | Research & Development | News; concerning: "United States Patent 8,366,902 - Methods and Systems for Producing Syngas; 2013; Abstract: Methods and systems are provided for producing syngas utilizing heat from thermochemical conversion of a carbonaceous fuel to support decomposition of at least one of water and carbon dioxide using one or more solid-oxide electrolysis cells. Government Interests: This invention was made with government support under Contract Number DE-AC07-05ID14517 awarded by the United States Department of Energy. The government has certain rights in the invention.";
hydrocarbon synthesis gas, a blend of Carbon Monoxide and Hydrogen, as can be generated, as in, for one example, the process described in our report of:
California Hydrogasifies Coal & Carbon-Recycling Wastes | Research & Development | News; concerning: "US Patent 7,500,997 - Steam Pyrolysis ... to Enhance the Hydro-Gasification of Carbonaceous Materials; 2009; Assignee: The Regents of the University of California; Abstract: A process and apparatus for producing a synthesis gas for use as ... feed into a Fischer-Tropsch reactor to produce a liquid fuel in a substantially self-sustaining process. In one embodiment, a slurry of carbonaceous material in water, and hydrogen from an internal source, are fed into a hydro-gasification reactor to generate methane rich producer gases which are fed into a steam pyrolytic reformer to generate synthesis gas comprising hydrogen and carbon monoxide. (And) wherein the carbonaceous material comprises municipal waste, biomass, wood, coal, or a natural or synthetic polymer";
from Coal, perhaps supplemented with any and all sorts of Carbon-recycling waste materials, can be "reformed", to borrow a term from the petroleum refining industry, using a technology like that disclosed in:
USDOE Idaho Lab Recycles More CO2 | Research & Development | News; concerning: "Model of High Temperature H2O/CO2 Co-electrolysis; 2007; Research Organization: Idaho National Laboratory (INL); Sponsoring Organization: USDOE; (High-temperature) co-electrolysis of steam and carbon dioxide in a planar solid oxide electrolyzer (SOE) using solid oxide fuel cell technology. A research program is under way at the Idaho National Laboratory (INL) to simultaneously address the research and scale-up issues associated with the implementation of planar solid-oxide electrolysis cell technology for syngas production from CO2 and steam";
so that any Carbon Dioxide which might be present in the synthesis gas is converted, along with Steam, into more of the desired Carbon Monoxide and Hydrogen components of, as the University of California states it above: "synthesis gas for use as ... feed into a Fischer-Tropsch reactor to produce a liquid fuel".
As it happens, the partial-combustion process that generates the synthesis gas isn't the only component of such a synthetic fuel production system that generates Carbon Dioxide.
By way of explanation, as instructed by our USDOE, via:
NETL: Gasifipedia; and:
"Liquid transportation hydrocarbon fuels can be produced from syngas via a well-known catalytic chemical reaction called Fischer-Tropsch (FT) synthesis, named after the original German inventors, Franz Fischer and Hans Tropsch in the 1920s. During World War II, FT synthesis provided the needed liquid hydrocarbon fuels for the German war effort. Later, facing isolation during the apartheid era, South Africa turned to FT synthesis from coal gasification to supply significant quantities of its hydrocarbon fuel needs. Since then, many refinements and adjustments to the technology have been made, including catalyst development and reactor design. (The) technology is often referred to as coal-to-liquids (CTL) and ... (examples) of current operating CTL plants include Sasol's Sasolburg I and II plant ... . The Fischer-Tropsch process is a catalytic chemical reaction in which carbon monoxide (CO) and hydrogen (H2) in the syngas are converted into hydrocarbons of various molecular weights according to the following equation:
(2n + 1)H2 + nCO = CnH(2n + 2) + nH2O; Where "n" is (a whole number, and, thus), for n=1, the reaction represents the formation of methane (CH4), which in most CTL ... applications is considered an undesirable byproduct. The Fischer-Tropsch process conditions are usually chosen to maximize the formation of higher molecular weight hydrocarbon liquid fuels which are higher value products. There are other side reactions taking place in the process, among which the water-gas-shift reaction:
CO + H2O = H2 + CO2 is predominant. Depending on the catalyst, temperature, and type of process employed, hydrocarbons ranging from methane to higher molecular paraffins and olefins can be obtained. Small amounts of low molecular weight oxygenates (e.g., alcohol and organic acids) are also formed". - - -
Note, that, the "water-gas-shift reaction":
Water gas shift reaction - Wikipedia, the free encyclopedia; "is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen (and) is an important industrial reaction (that) was discovered ... in 1780";
also occurs as a "side reaction" in a Fischer-Tropsch reactor that is, primarily, converting Carbon Monoxide and Hydrogen into hydrocarbons.
That, even though the Sabatier reaction, as in:
Sabatier reaction - Wikipedia, the free encyclopedia;"involves the reaction of hydrogen with carbon dioxide at elevated temperatures ... and pressures in the presence of a nickel catalyst to produce methane and water. It is described by the following reaction: CO2 + 4H2 = CH4 + 2H2O"; and:
West Virginia Coal Association | CO2 Solution Wins Nobel Prize - in 1912 | Research & Development; "Paul Sabatier; The Nobel Prize in Chemistry 1912";
is also converting Carbon Dioxide and Hydrogen into substitute natural gas Methane.
That's all pretty much clear as mud, we suppose, but, the gist of it is, that, in a Fischer-Tropsch or related hydrocarbon synthesis reactor, wherein Carbon Monoxide and Hydrogen syngas - - - as can be made by Coal and biomass gasification, as in our above-cited report concerning "US Patent 7,500,997 - Steam Pyrolysis ... to Enhance the Hydro-Gasification of Carbonaceous Materials", which syngas is perhaps "reformed" via an integrated process of "High Temperature H2O/CO2 Co-electrolysis" like that disclosed by "United States Patent 8,366,902 - Methods and Systems for Producing Syngas", to break any CO2 and H2O co-produced during the Coal and biomass gasification down into more of the desired Carbon Monoxide and Hydrogen - - - are reacted over a catalyst to synthesize liquid and gaseous hydrocarbon fuels, some amount of Carbon Dioxide is typically again co-produced as a byproduct of the hydrocarbon synthesis reaction.
The co-production of CO2 in a hydrocarbon synthesis reaction is unwanted since it represents an inefficiency, a wastage of available Carbon that would preferably be consumed in the synthesis of the desired hydrocarbons. And, effort has been made to improve the Fischer-Tropsch synthesis reaction itself, so that there is less "water gas shift reaction" and so that there is, thus, less wastage of the available Carbon. And, perhaps strangely, among the folks who have been working to improve the hydrocarbon synthesis reaction in that regard, that is, to make the Fischer-Tropsch process more efficient, is NASA, our National Aeronautics and Space Administration. As seen in excerpts from the initial link in this dispatch to:
"United States Patent 7,393,876 - Fischer-Tropsch Catalysts ;
Date: July 1, 2008
Inventors: James White and Jesse Taylor, Colorado
Assignee: Eltron Research, Inc., Boulder
(www.eltronresearch.com/index.html; "Eltron R&D is over 30 years old and has experience in catalysis, materials, chemicals, analytical services, engineering design, prototype development, and technology feasibility studies".)
Abstract: Catalyst compositions and methods for F-T synthesis which exhibit high CO conversion with minor levels (preferably less than 35% and more preferably less than 5%) or no measurable carbon dioxide generation. F-T active catalysts are prepared by reduction of certain oxygen deficient mixed metal oxides.
Government Interests: This invention was funded under NASA SBIR contract NNM04AA78C. The United States government has certain rights in this invention.
Claims: A process for the production of hydrocarbons comprising the steps:
(a) introducing a feed gas stream comprising hydrogen, carbon monoxide, and carbon dioxide into a Fischer Tropsch reactor;
(b) reacting said feed gas in the reactor employing a mixed metal oxide catalyst where the reactor is operated at a pressure from 100 psig to 1200 psig and a temperature between 175 C to 350 C. wherein the CO conversion is greater than 20 mole percent; and:
(c) collecting product from said reactor where the product comprises hydrocarbon and water wherein the total mass flow rate of CO2 out of the reactor is less than or equal to the amount of CO2 in the feed gas stream wherein the mixed metal oxide catalyst is a catalyst having the formula (as specified).
The method ... wherein the total mass flow rate of CO2 out of the reactor is less than 90% of the CO2 in the feed stream by mass.
(This catalytic hydrocarbon synthesis technology, thus, not only just helps to prevent the formation of CO2 in the hydrocarbon synthesis reaction itself, by limiting the water gas shift reaction, but, much as in the USDOE's process disclosed in our report of:
USDOE CO2 + Hydrogen = Methanol and Ethanol | Research & Development | News; concerning: "United States Patent 7,858,667 - Alcohol Synthesis from CO or CO2; 2010; Inventors: Jianli Hu, et. al., WA and TX;
Assignee: Battelle Memorial Institute, WA;Abstract: Methods for producing alcohols from CO or CO2 and H2 utilizing a palladium-zinc (Pd--Zn) on alumina catalyst are described. Methods of synthesizing alcohols over various catalysts in microchannels are also described. Ethanol, higher alcohols, and other C2+ oxygenates can be produced utilizing Rh--Mn (Rhodium and Manganese) or a Fisher-Tropsch catalyst. A portion of this work was funded by the U.S. DOE ... under Contract DE-AC06-76RL01830. Claims: A method of synthesizing alcohols from CO or CO2 comprising: flowing a reactant gas mixture comprising H2 and CO or CO2 into contact with a catalyst; wherein the catalyst comprises a Pd--Zn alloy dispersed on alumina; and forming an alcohol or alcohols";
it limits as well the Sabatier CO2 + H2 = Methane reaction, so that more liquid, as opposed to gaseous, fuels are synthesized from the syngas, even if that syngas contains, in addition to Carbon Monoxide, some appreciable amount of Carbon Dioxide; and, it is, thus, actually able to consume most of any CO2 that might be present in the feed gas stream for the synthesis of liquid hydrocarbons; as emphasized in additional claims.)
The method ... wherein the total mass flow rate of CO2 out of the reactor is less than the amount of CO2 in the feed gas stream.
The method ... wherein the reactor is a slurry reactor (or) a fixed bed reactor (and) wherein the CO conversion is greater than 50%.
A method for reductive oligomerization of carbon monoxide (CO) in the presence of molecular hydrogen (H2) which comprises the step of contacting a feed stream comprising CO and H2 with an activated reduced catalyst which is formed by reduction of an oxygen-deficient metal oxide (as described, and) wherein the product stream contains hydrocarbons the majority of which have 5 or more carbon atoms.
The method ... further comprising the step of activating the mixed metal oxide catalyst by reduction prior to reacting the feed gas with the catalyst.
(The above "activating the mixed metal oxide catalyst by reduction" is a common feature disclosed in many, if not most, disclosures of Fischer-Tropsch processes. The chemical "reduction" seems most often specified to be accomplished by passing a stream of pure Hydrogen over the catalyst for some variable period of time before introducing the synthesis gas blend.)
Background and Field: Fischer-Tropsch (F-T) synthesis involves the catalytic reductive oligomerization of carbon monoxide in the presence of hydrogen as (as described).
Generally, the process converts a mixture of CO and molecular hydrogen into a mixture of hydrocarbons, including saturated hydrocarbons and olefins. Oxygenated hydrocarbons, such as alcohols, and sometimes aromatics may also be formed in a F-T process. More specifically, products of F-T processes can include gaseous, liquid, heavy oil, and wax products which can be further upgraded to various fuels (gasoline, jet fuel, diesel fuel, etc.) and other value-added hydrocarbon products, particularly liquid hydrocarbons.
A mixture of CO and hydrogen for the F-T process can be generated in a number of ways, and in particular can be synthesis gas "syngas." Syngas is available from a variety of sources and can, for example, be prepared by coal, biomass, or waste gasification processes ... . The ratio of H2 to CO in syngas from a given source may vary significantly (e.g., from about 0.3 up to 3 or higher) and a given F-T catalyst may be sensitive to that ratio (i.e., exhibit increased or decreased activity or changes in selectivity dependent upon that ratio.)
While a number of metals demonstrate F-T activity, only four metals: Iron, Cobalt, Ruthenium, and Nickel are regarded in the art as usefully active. The utility of F-T catalysts is decreased if they exhibit high methanation activity.
High levels of catalytic methane formation from CO and hydrogen by a catalyst ... decreases the utility of that catalyst for formation of higher hydrocarbons. For example, the utility of Nickel on conventional metal oxide supports as an F-T catalyst is decreased by its high methanation activity. In contrast, Nickel supported on some molecular sieves such as zeolite Y does not exhibit high methanation activity making it a more useful F-T catalyst.
Features of established catalytic systems for F-T synthesis are summarized hereafter. Iron and cobalt-based systems have generally received more attention and certain of these systems have been commercialized. Iron and cobalt based systems have their origins with Fischer and Tropsch who developed alkalized iron turning- and Kieselguhr-supported cobalt/magnesia (or thoria) catalysts ... . Iron-based catalysts are typically employed, for example, where H2:CO ratios are low (e.g., 0.5 to 1.5) as might be found in coal or biomass systems.
Advantages of iron-based catalyst are generally lower cost, relative insensitivity to reaction conditions, such as H2:CO ratio and the presence of low levels of sulfide impurities; and their ability to function at low H2:CO ratios. Cobalt-based catalysts are considerably more expensive and can show strong sensitivity to H2:CO ratio. However, cobalt-based catalysts, in general, exhibit higher overall activity and increased mechanical strength compared to iron-based catalysts. Additionally, under like conditions, cobalt-based catalysts tend to produce a distribution of hydrocarbons that is more heavily weighted toward high carbon number species (i.e., give a higher chain growth probability) than the hydrocarbon distribution produced using iron-based catalysts. Iron-based F-T catalysts can also produce copious quantities of carbon dioxide in the F-T process, which is generally detrimental, because they can exhibit activity as an internal forward water-gas-shift catalyst.
The utility of F-T synthesis catalysts is significantly decreased if there is significant conversion of CO to CO2 rather than to value-added hydrocarbon and oxygenated hydrocarbon products.
Preferred F-T synthesis catalysts exhibit low CO2 production particularly in combination with high CO conversion rates. An F-T catalyst may exhibit product selectivity for a desirable product composition. For example, certain F-T catalysts exhibit selectivity for production of higher molecular weight hydrocarbons, for production of low molecular weight hydrocarbons (e.g., low molecular weight olefins), for production of product with higher or lower amounts of olefinic materials, or for the production of product with higher or lower amounts of oxygenated materials (e.g., alcohols). Product selectivity of an F-T catalyst can be a significant factor in the utility of that catalyst for a given application.
The design and selection of F-T catalysts for low CO2 production and selective applications should consider the (specified and described issues related to catalyst) composition ... .
F-T synthesis is a process that involves an unusually high degree of interaction between reaction chemistry, catalyst properties, mass transport, reactor design, overall system integration, and economics. Catalyst selection and reactor design for a given F-T application depends upon all of these factors.
Because cobalt catalysts are sensitive to feed composition (i.e., H2:CO ratio), the F-T system employing the cobalt catalyst may then require a water-gas-shift module upstream of the F-T catalyst when low hydrogen content sources (such as coal) are used to ensure that the appropriate H2:CO ratio is provided. In contrast, unsupported baseline precipitated iron catalysts may not be amenable for use in slurry phase or fluidized bed reactors because of their lower mechanical strength and correspondingly high attrition rate, but would be preferred in other applications because of their relative insensitivity to H2:CO ratio and their product selectivity characteristics (i.e., greater selectivity for production of C5 or higher products at low H2:CO ratios). There is a continuing need in the art for catalysts for F-T synthesis which exhibit one or more beneficial characteristics for a given application, given H2/CO feedstock, given reactor design, and/or a desired product composition.
Summary: The present invention provides catalyst compositions and methods for F-T synthesis which exhibit high CO conversion with minor levels (preferably less than 35% and more preferably less than 5%) or no measurable carbon dioxide generation.
More specifically, the invention provides method for hydrocarbon production employing a feed stream comprising hydrogen, carbon monoxide, and carbon dioxide in a F-T reactor wherein the total mass flow rate of CO2 out of the reactor is less than or equal to the amount of CO2 in the feed gas stream. Preferably the total mass flow rate of CO2 out of the reactor is less than 90% by weight of the CO2 in the feed stream. More preferably, the total mass flow rate of CO2 out of the reactor is less than the amount of CO2 in the feed gas stream.
The invention also provides such catalytic processes where CO conversion is 75% or more.
(In other words, the "catalyst compositions" developed by NASA contractors herein will consume some of the Carbon Dioxide fed to it in the synthesis of higher-weight hydrocarbons while also consuming most of the Carbon Monoxide. And, as indicated, a feature of more recent, more advanced Fischer-Tropsch reactor designs is multiple stages, so that, ultimately, all, or nearly all, of the Carbon Oxides are consumed. See, for example:
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; Inventors: Ralph Schellen, et. al., Germany and Texas; 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";
wherein Bayer Corporation has also improved the physical design of the Fischer-Tropsch reactor by segmenting it into a "series" of "connected reaction zones".)
In preferred embodiments employing catalysts of this invention, F-T synthesis is carried out to achieve highest CO conversion without excessive CO2 generation (greater than 35% conversion to CO2). F-T synthesis can be carried out using the methods and catalysts herein to obtain CO conversion of greater than 60 mole %. Methods of this invention can achieve CO conversion of between 65 mole % and 90 mole % preferably without excessive CO2 production. Conversion to CO2 is preferably minimized and when CO conversion is between 65 mole % and 90 mole % CO2 conversion is preferably less than 35 mole % and more preferably less than 20 mole %. In addition, it is preferred that conversion to methane is minimized and preferably conversion to methane is less than 10 mole % and more preferably less than 8 mole %. In more preferred embodiments, selectivity for products other than CO2 and methane is 70 mole % -100 mole %.
(In other words, it is possible to convert nearly all of the Carbon Monoxide fed into this catalytic system into desired higher-weight hydrocarbons, while co-production of CO2 and Methane are minimized.)
In a specific embodiment the methods of this invention the methods employ an oxygen-deficient mixed metal catalyst which have been exposed to a reducing gas to activate the catalyst. The unfinished catalysts of the invention have the formula: (as specified).
The invention provides methods for reductive oligomerization of carbon monoxide (CO) in the presence of molecular hydrogen (H2) which comprise the step of contacting a mixture comprising CO and H2 with a catalyst which is an oxygen-deficient metal oxide that has been subjected to reduction prior to contact with the mixture.
The feed mixture optionally contains CO2.
The method is conducted under temperature and pressure conditions selected to achieve a desired product composition. Preferred products contain hydrocarbon species having 5 or more carbon atoms (C5+). In preferred embodiments the catalytic reductive oligomerization is conducted between about 175 and 350 C and more preferably is conducted at a temperature of 300C. or less.
Fischer-Tropsch (F-T) synthesis involves the catalytic reductive oligomerization of carbon monoxide in the presence of hydrogen to form hydrocarbons (paraffinic and olefinic), Generally, the process converts a mixture of CO and molecular hydrogen into a mixture of hydrocarbons, including saturated hydrocarbons and olefins. The product stream of F-T synthesis contains a mixture of hydrocarbon products having a range of molecule weights and including gaseous and liquid hydrocarbons at reaction temperature. The product stream when assessed at ambient temperature and pressure can contain gases, liquids and waxy hydrocarbons. The product stream may contain linear and branched hydrocarbons. The nature of the product stream generally depends upon the reaction conditions (e.g., temperature) and the catalyst employed. When the reaction is conducted at lower temperatures the product stream generally contains a majority of linear hydrocarbons.
Hydrocarbons in the product stream can be characterized by the number of carbon atoms present, and can be grouped into fractions based on a common carbon number. ... It is generally known in the art that F-T reaction conditions can be adjusted to vary the hydrocarbon content of the product stream.
A preferred F-T synthesis product stream is a hydrocarbon product in which the majority of hydrocarbons have more than 5 carbon atoms (herein such products are called C5+ products). These may include hydrocarbon fractions in which the majority of the hydrocarbons contain 4-12 carbon atoms, as well as hydrocarbon fractions in which the majority of the hydrocarbons contain 10-22 carbon atoms. Such fractions are a useful source for fuels such as diesel, gasoline and aviation fuels.
F-T catalysts of this invention can be employed to generate hydrocarbon products ... which are useful in fuel applications.
The feed stream gas for the F-T reactor comprises a mixture of H2 and CO, (synthesis gas) H2/CO mixtures suitable as a feedstock for conversion to hydrocarbons can be obtained from various sources, for example, from ... biomass and/or from coal gasification.
The feed stream gas may also contain off-gas recycle from an F-T reactor.
It is preferred that the molar ratio of hydrogen to carbon monoxide in the feed be greater than 0.5:1 (e.g., from about 0.67 to about 2.5). More preferably, the reactant gas contains hydrogen and carbon monoxide in a molar ratio of about 1.4:1 to about 2.3:1.
The feed stream gas can also contain CO2.
The feed stream gas preferably contains only low concentrations of compounds or elements that can detrimentally affect catalyst activity. It may be necessary or beneficial to remove or decrease the concentration of such detrimental materials from the feed stream gas by pre-treatment to decrease or avoid catalyst deactivation. Potentially detrimental species include hydrogen sulfide, hydrogen cyanide, ammonia, and carbonyl sulfides.
The F-T product stream contains hydrocarbons, water and may contain unconverted CO as well as CO2.The feed stream may contain CO2 which survives the reaction and exits in the product stream. In addition, CO2 may be produced in the reactor which is generally undesirable.
In specific embodiments herein employing catalysts of this invention, only very low levels or no CO2 is produced in the F-T reactor.
CO2 levels can be assessed, for example, by measurement of the total mass flow rate of CO2. When this measurement is used, the total mass flow rate of CO2 which leaves the reactor is preferably less than or equal to the amount of CO2 in the feed gas stream. In specific embodiments, F-T methods of this invention can be employed to generate product steams in which the mass flow rate of CO2 out of the reactor is less than 90% of the mass flow rate of CO2 in the feed stream. In specific embodiments, F-T methods of this invention can be employed to generate product steams in which the mass flow rate of CO2 out of the reactor is less than the mass flow rate of CO2 in the feed stream.
Employing catalysts of this invention (and in) preferred embodiments ... of this invention CO conversion rates greater than ... 75 mole % can be obtained.
The invention further relates to methods of carrying out Fischer-Tropsch synthesis employing one or more catalysts of the present invention (and) carried out in any known reactor type ... .
In specific embodiments, the invention provides methods for conversion of CO and hydrogen mixtures, particularly those generated by coal, biomass, or waste gasification ... to products containing mixtures of hydrocarbons, particularly products that are liquid hydrocarbon mixtures. In more specific embodiments, the invention provides methods for preparation of clean fuels, such as diesel fuels, which have little or no sulfur or nitrogen contaminants.
There are four preferred reactor types that can be employed with the catalysts of the present invention: 1)
The choice of reactor type also depends on the efficiency of heat removal. This influences not only the FTS reaction but activation of the catalyst. For example, copper and Fe-containing catalysts are particularly subject to deactivation by sintering if the reduction exothermicity is not adequately removed. Fixed bed reactors are least efficient in heat removal and the other types better suited to this purpose. The same can be said for the FTS reaction.
F-T synthesis can be carried out in fixed bed reactors in which the reactant gas mixture is passed over a bed of solid catalyst. For example, a fixed bed reactor can comprise a plurality of tubes or catalyst containers within a reactor shell. Due to the high exothermicity of the synthesis, all F-T reactor designs require adequate provisions for temperature control to prevent reaction runaway. In fixed bed reactors, excess heat can be carried away by forming steam from water, which is added to the reactor shell surrounding the tubes.
F-T synthesis can be carried out in fluidized bed reactors. Fluidized bed reactors for low-temperature F-T reactors are also called slurry bubble column, slurry bed, slurry phase, or multiphase reactors, and consist of a reactor shell containing a slurry comprising catalyst particles and a hydrocarbon liquid phase.
The reactor shell and the slurry are typically cooled employing cooling coils.
The feed gas stream is introduced into the slurry. The reactor typically has a feed stream distribution system that introduces the feed stream at the bottom of the slurry, for example as small gas bubbles that rise up through the slurry. The gases of the feed stream diffuse through the liquid phase in the slurry encounter catalyst particles and react. Heavier hydrocarbons that may be produced are liquid under typical reactor operating temperatures and pressures and are incorporated into the slurry. Lighter gaseous products (at reaction temperature and pressure) and water vapor pass out of the slurry and can be collected as a product stream.
Unconverted reactants can be recycled.
The preferred operating temperature range of materials of the present invention depends on the composition of materials. In particular, Cobalt-containing materials are more active at a given temperature and are thus more useful at lower temperatures than Iron-containing materials ... (and) decreased production of heavier hydrocarbons, including waxes, is expected as the temperature is increased. In addition, increased aromatic content and chain branching, i.e., more favorable conditions for gasoline production, will occur."
There are a number of specifics related to the hydrocarbon synthesis reactions noted herein by NASA and Eltron Research which we have treated in previous reports. We haven't, to avoid making this report insufferably long, made reference to those past reports to further explain and illuminate those specifics addressed by NASA, but will be treating them again separately in reports to follow.
But, we wanted to again emphasize, as the full Disclosure does, that tail gas from the hydrocarbon synthesis "can be recycled", or, further reacted in a series of sequential "FT" reactors, as in Bayer Corporation's process of the above-cited "United States Patent 8,557,880 - Multi-stage Adiabatic Method for Performing the Fischer-Tropsch Synthesis", thus maximizing conversion of the hydrocarbon synthesis gas; and, since the "reactor shell and the slurry are typically cooled employing cooling coils"; it is feasible to consider, as we will see especially in some reports to follow, co-producing some amount of electricity from the hydrocarbon synthesis reaction itself.
And, in sum, since the synthesis gas, "CO and hydrogen mixtures", can be "generated by coal, biomass, or waste gasification", with some CO2 being naturally recycled in the "biomass" and "waste", and, since the hydrocarbon synthesis "feed stream gas can also contain CO2", some of which can be consumed in the hydrocarbons synthesis reaction, and, since the hydrocarbon synthesis reaction in the "F-T reactor" designed herein by NASA and Eltron Research itself co-produces "only very low levels or no CO2", it is conceivable, that, in total, the process of our subject, "US Patent 7,393,876 - Fischer-Tropsch Catalysts", could actually consume some amount of Carbon Dioxide while it effects "gasoline production" from renewable "biomass" and "waste" combined with some of our abundant United States of America Coal.