We often refer, in the course of our reportage, to ExxonMobil's "MTG"(r), methanol-to-gasoline, technology, wherein the Methanol is most often posited to be made from Coal.
The "MTG"(r) process makes use of a what is sometimes described as an "acidic catalyst", or catalyst support, based on the zeolite mineral designated as "ZSM-5", which shorthand label actually conveys some technical information about the specific compound to those blessed with intimate knowledge of zeolites, which is a broad family of both natural and synthetic minerals, and their sub-microscopic structures.
A few examples of our earlier reportage concerning that technology have included:
Mobil Oil 1977 Coal-Derived Alcohols to Gasoline | Research & Development; which concerns, primarily: "United States Patent 4,025,575 - Process for Manufacturing Olefins; 1977; Mobil Oil Corporation, NY; Abstract: A lower alcohol and/or ether feed is selectively converted to a mixture of light olefins, including ethylene and propylene, by catalytic contact of the feed, for example methanol or dimethyl ether, ... with certain crystalline aluminosilicate zeolite catalysts exemplified by HZSM-5"; and:
Mobil Oil Coal to Methanol to Gasoline | Research & Development; which provides details of: "United States Patent 4,447,310 - Production of Distillates through Methanol to Gasoline; 1984; Mobil Oil Corporation, NY;
Abstract: A process for producing a wide slate of fuel products from coal is provided by integrating a methanol-to-gasoline conversion process with coal liquefaction and coal gasification".
The above process of USP 4,447,310 is actually quite advanced, and a close read is recommended. It does, in fact, spell out how any carbonaceous residues remaining after an initial direct liquefaction of Coal, using an hydrogenated Coal liquefaction solvent, perhaps, we submit, as in WVU's "West Virginia Process" which uses, as a solvent, the hydrogenated version of the Coal tar Naphthalene, "tetralin", can, after that initial liquefaction, be gasified with Steam to make a secondary product consisting of Methanol synthesis gas.
And, we note in passing that Mobil's then-future marriage partner, Exxon, was, as well, in the same time frame, at work on closely-related technology, as witnessed, for one example, by:
Exxon 1982 Coal + Steam = Methanol | Research & Development; which further explains: "United States Patent 4,348,486 - Production of Methanol via Catalytic Coal Gasification; 1982; Assignee: Exxon Research and Engineering Company, NJ".
In any case, we submit herein further testament to, and explanation of, the technology developed by Mobil Oil Corporation, more than three decades ago, which would have allowed us in the years since to have begun making a broad range of both industrially-useful alcohols and gasoline from our abundant Coal.
Comment, with additional references, follows excerpts from the initial link in this dispatch to:
"United States Patent 4,086,262 - Conversion of Synthesis Gas to Hydrocarbon Mixtures
Date: April, 1978
Inventors: Clarence Chang, et. al., NJ and PA
Assignee: Mobil Oil Corporation, NY
Abstract: Contacting a mixture of carbon monoxide and hydrogen with an intimate mixture of a carbon monoxide reduction catalyst, such as a Fischer-Tropsch catalyst or a methanol synthesis catalyst, and an acidic crystalline aluminosilicate having a pore dimension greater than about 5 Angstroms to produce hydrocarbon mixtures useful in the manufacture of heating fuels, high octane gasoline, aromatic hydrocarbons, and chemicals intermediates.
Claims: A method for producing hydrocarbons, which comprises: contacting synthesis gas having a ratio of hydrogen-to-carbon oxides of from 0.2 to 6.0 with a heterogeneous catalyst (under a broad range of specified conditions, and which catalyst comprises) an intimate mixture of an inorganic carbon monoxide reducing catalyst and a selective acidic crystalline aluminosilicate that has pore diameter greater than about 5 Angstroms; a silica-to-alumina ratio of at least 12; a constraint index within the range of 1 to 12; and, recovering hydrocarbons containing quantities of aromatic hydrocarbons.
The method ... wherein said inorganic substance characterized by catalytic activity for the reduction of carbon monoxide constitutes from about one weight percent to about eighty weight percent of the active components of said heterogeneous catalyst.
The method ... wherein said inorganic substance and said acidic crystalline aluminosilicate are in the same catalyst particle.
The method ... wherein said inorganic substance and said acidic crystalline aluminosilicate are in separate catalyst particles.
The method ... wherein said acidic crystalline aluminosilicate is a H-ZSM-5 crystalline zeolite.
The method ... wherein said carbon monoxide reducing catalyst is a Fischer-Tropsch catalyst and wherein aromatic hydrocarbons are separated from said recovered hydrocarbons.
The method ... wherein said inorganic substance comprises iron.
(As we have earlier reported and documented, the "MTG"(r) technology is intimately related to, and somewhat derivative of, the older Fischer-Tropsch Coal liquefaction technology which, along with the Bergius and other processes, helped to supply Germany with liquid fuels made from Coal during WWII.)
The method ... wherein the increased quantity of aromatic hydrocarbons are rich in toluenes and xylenes.
(Remember that Gasoline is blended up from "BTX", i.e., benzene, toluene and xylene.)
The method ... wherein said catalyst is formulated from a metal or compound of zinc, iron, cobalt, nickel, ruthenium, thorium, rhodium, osmium or mixtures thereof.
(Even though we refer to the "ZSM-5" zeolite as being the catalyst for the needed reactions, it should more properly be referred to as the "catalyst support". As we understand it, the number "5" refers to the sizes of the submicroscopic pores in the zeolite mineral structure which are, apparently, ideally-sized to serve as a matrix for bringing the atoms of the catalytic metal, i.e., "zinc, iron", etc., into intimate contact with the other molecules being reacted.)
Background and Field: This invention is concerned with an improved process for converting synthesis gas, i.e., mixtures of gaseous carbon oxides with hydrogen or hydrogen donors, to hydrocarbon mixtures. In one aspect, this invention is particularly concerned with a process for converting synthesis gas to hydrocarbon mixtures rich in aromatic hydrocarbons. In another aspect, this invention is concerned with a process for converting synthesis gas to hydrocarbon mixtures particularly rich in liquefiable petroleum gases such as propane. In still another aspect, this invention is concerned with providing novel catalysts for the conversion of synthesis gas to hydrocarbon mixtures.
Processes for the conversion of coal ... to a gaseous mixture consisting essentially of hydrogen and carbon monoxide, or of hydrogen and carbon dioxide, or of hydrogen and carbon monoxide and carbon dioxide, are well known. Although various processes may be employed for the gasification, those of major importance depend either on the partial combustion of the fuel with an oxygen-containing gas or on the high temperature reaction of the fuel with steam, or on a combination of these two reactions.
The techniques for gasification of coal ... are not considered to be per se inventive here.
(In other words, we already darned-well knew, back in 1978, how to do a pretty good job of converting Coal into a hydrocarbon synthesis gas.)
It would be very desirable to be able to effectively convert synthesis gas, and thereby coal ... to highly valued hydrocarbons such as motor gasoline with high octane number, petrochemical feedstocks, liquefiable petroleum fuel gas, and aromatic hydrocarbons.
The wide range of catalysts and catalyst modifications disclosed in the art and an equally wide range of conversion conditions for the reduction of carbon monoxide by hydrogen provide considerable flexibility toward obtaining selected boiling-range products. Nonetheless, in spite of this flexibility, it has not proved possible to make such selections so as to produce liquid hydrocarbons in the gasoline boiling range which contain highly branched paraffins and substantial quantities of aromatic hydrocarbons, both of which are required for high quality gasoline, or to selectively produce aromatic hydrocarbons particularly rich in the benzene to xylenes range.
(Again, the "benzene" and "xylene" components of BTX gasoline blending stock.)
Recently it has been discovered that synthesis gas may be converted to oxygenated organic compounds and these then converted to higher hydrocarbons, particularly high octane gasoline, by catalytic contact of the synthesis gas with a carbon monoxide reduction catalyst followed by contacting the conversion products so produced with a special type of zeolite catalyst in a separate reaction zone.
(The phrase "oxygenated organic compounds" would include Methanol and Ethanol, for instance.)
It is an object of the present invention to provide an improved process for converting fossil fuels to a hydrocarbon mixture that contains large quantities of highly desirable constituents. It is a further object of this invention to provide a more efficient method for converting a mixture of gaseous carbon oxides and hydrogen to a mixture of hydrocarbons. It is a further object of this invention to provide an improved method for converting synthesis gas to a hydrocarbon mixture rich in aromatic hydrocarbons.
It is a further object of this invention to provide a method for converting synthesis gas to petrochemicals feedstocks, including olefins. It is a further object of this invention to provide an improved method for converting synthesis gas to propane fuel. It is a further object of this invention to provide novel catalysts for the conversion of synthesis gas.
(Make note that some quite-valuable by-products, i.e., "propane" and "petrochemicals feedstocks", are made herein from Coal, along with all the "large quantities of" other, "highly desirable", stuff.)
Synthesis gas for use in this invention consists of a mixture of hydrogen gas with gaseous carbon oxides including carbon monoxide and carbon dioxide.
The synthesis gas may be prepared from fossil fuels by any of the known methods, including ... partial combustion of coal ... .
The term fossil fuels, as used herein, is intended to include anthracite and bituminous coal, lignite, ... (and) including coked coal ... .
(Note, that, since "coked coal" can be utilized, the potential exists to, first, as seen for one instance in:
Coke Oven Gas to Synfuel | Research & Development; concerning: "The 120 000 t/a methanol project based on coke oven gas designed by the Second Design Institute of Chemical Industry started production in Kingboard (Hebei) Coking Co., Ltd. (and is not) the first methanol unit based on coke oven gas in China";
effect, through coking, an initial, perhaps more economical, extraction of Methanol synthesis gas from Coal, before subjecting the resultant Coke to the process of "gasification ... with steam" as suggested herein by US Patent 4,086,262.)
Other carbonaceous fuels such as peat, wood and cellulosic waste materials also may be used.
(Note the potentials for Carbon recycling and some amount of sustainability.)
It is contemplated that the synthesis gas for use in this invention includes art-recognized equivalents to the already-described mixtures of hydrogen gas with gaseous carbon oxides. Mixtures of carbon monoxide and steam, for example, or of carbon dioxide and hydrogen, to provide adjusted synthesis gas by in situ reaction, are contemplated. Furthermore, when the novel process of this invention is used to produce hydrocarbon mixtures rich in aromatic hydrocarbons ... a hydrogen-donor such as methane ... may be charged with the gaseous carbon oxides mixture to some advantage.
(The above is oblique confirmation of the fact we have many times documented, as for just one instance, in:
Standard Oil 1987 CO2 + CH4 = Syngas | Research & Development; in which is discussed:"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 ... contacting ... light hydrocarbons with carbon dioxide ... (and) wherein the light hydrocarbon is methane"; that:
Methane can be reacted, "reformed", with Carbon Dioxide, and made to serve as the "hydrogen donor", in reactions where both are converted into a blend of Hydrogen and Carbon Monoxide, i.e., hydrocarbon synthesis gas.
And, further, as 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 (including) methanol (and/or) methane";
we can make that Methane, along with some more of the Methanol that is the key intermediary, transient product of our subject US Patent 4,086,262 process for Coal conversion to Gasoline, out of Carbon Dioxide. And, make special note of the passage immediately following.)
Should the purified synthesis gas be excessively rich in ... hydrogen, it may be adjusted into the preferred range by the addition of carbon dioxide.
It is preferred, for the purpose of this invention, to utilize as one component of the heterogeneous catalyst a substance that has catalytic activity for the reduction of carbon monoxide to organic products having at least one carbon-to-carbon or carbon-to-oxygen bond. Prominent substances of this type include the metals or oxides of zinc, iron, cobalt, (etc.)
The acidic crystalline aluminosilicate component of the heterogeneous catalyst is characterized by a pore dimension greater than about 5 Angstroms, i.e., it is capable of sorbing paraffins having a single methyl branch as well as normal paraffins, and it has ... no pore dimension greater than about 5 Angstroms.
The crystalline aluminosilicates herein referred to, also known as zeolites, constitute an unusual class of natural and synthetic minerals. They are characterized by having a rigid crystalline framework structure composed of an assembly of silicon and aluminum atoms, each surrounded by a tetrahedron of shared oxygen atoms, and a precisely defined pore structure.
(And, they are not, we assure you, uncommon, or, expensive to make. Some, as we have earlier documented, and, as seen additionally in:
http://www.energy-based.nrct.go.th/Article/Ts-3%20synthesis%20of%20zsm-5%20zeolite%20from%20lignite%20fly%20ash%20&%20rice%20h; which concerns: "Synthesis of ZSM-5 Zeolite from Fly Ash and Rice Husk Ash; Kasetsart University, Thailand; 2003";
can be extracted or synthesized from Coal-fired power plant fly ash.)
Alternatively, one may select catalyst and operating conditions in such a manner ... to produce normally gaseous hydrocarbons having at least one carbon-to-carbon bond as the predominant product, or hydrocarbon streams rich in internal olefins. Such products have value as petrochemical feedstocks, and for the manufacture of liquefiable petroleum fuel. The intimate mixtures, some of which are distinctly novel, not only produce highly desirable products with good selectivity but in many cases produce them either with extraordinarily high conversion per pass, or under mild conditions, or sometimes both.
The heterogeneous catalyst may be contained as a fixed bed, or a fluidized bed may be used. The product stream containing hydrocarbons, unreacted gases and steam may be cooled and the hydrocarbons recovered by any of the techniques known in the art, which techniques do not constitute part of this invention. The recovered hydrocarbons may be further separated by distillation or other means to recover one or more products such as high octane gasoline, propane fuel, benzene, toluene, xylenes, or other aromatic hydrocarbons.
It has further been discovered that synthesis gas containing sulfur moieties, such as hydrogen sulfide, may be efficiently converted to hydrocarbons by contacting such synthesis gas with a special catalyst composition, with the above composition, which is relatively insensitive to sulfur and whose activity and selectivity may even be improved as well as restored after continuous exposure to sulfur moieties in the synthesis gas feed. This aspect of this invention is concerned with the catalytic conversion of such sulfur containing synthesis gas to desired hydrocarbon products including gasoline boiling range aromatics and/or olefins wherein the catalyst is continuously or intermittently subjected either by design or by accident to contact with sulfur components in the synthesis gas."
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So, as documented in other of our reports, such as:
Allied Chemical Liquefies Coal with CO & H2S | Research & Development; concerning: "United States Patent 4,235,699 - Solubilization of Coal with Hydrogen Sulfide and Carbon Monoxide; 1980; Assignee: Allied Chemical Corporation; Abstract: Conversion of coal to products soluble in common solvents and conversion of coal tar to products of lower molecular weight, effected in liquid or fused reaction medium using a hydrogenating reactant, are carried out employing hydrogen sulfide and carbon monoxide as the sole or major hydrogenating reactant, without need of elemental hydrogen or a hydrogen donor solvent";
a little "hydrogen sulfide", as our subject "US Patent 4,086,262" acknowledges might be co-produced by their specified "conversion of coal ... to a gaseous mixture consisting essentially of hydrogen and carbon monoxide ... and carbon dioxide", could actually serve as well in the synthesis of hydrocarbons, through the use of apparently known catalysts "whose activity and selectivity may even be improved as well as restored after continuous exposure to sulfur".
And, finally, we note that the process of our subject "US Patent 4,086,262" seems to us to be more of an integrated one, wherein Methanol, and perhaps other oxygenated alcohols, are produced only as intermediate and transient agents on the path to making the final products, as in: "synthesis gas may be converted to oxygenated organic compounds and these then converted to higher hydrocarbons, particularly high octane gasoline", from Coal.
In other words, the complete process apparently does produce Methanol, and other "oxygenated organic compounds", through the use of a combined "methanol synthesis catalyst, and an acidic crystalline aluminosilicate", from Coal; and, that Methanol is then, via the dual function of that combined "heterogeneous catalyst", transformed immediately and directly into "higher hydrocarbons".
If our admittedly limited understanding is correct, then it seems to us that supplemental Methanol, obtained from another source, could be added to the process of "US Patent 4,086,262" somewhere along the line.
And, if so, we have a suggestion as to where that supplemental Methanol could come from.
As in:
USDOE 1976 Atmospheric CO2 to Methanol | Research & Development; which makes report of: "United States Patent 3,959,094 - Electrolytic Synthesis of Methanol from CO2; 1976; Assignee: The USA as represented by the USDOE; Abstract: A method and system for synthesizing methanol from the CO2 in air using electric power";
we could make additional Methanol, to add to the process that makes Gasoline, via Methanol, from Coal, out of Carbon Dioxide.