http://www.anl.gov/PCS/
Back in 2009, we made brief report of a Coal-to-Gasoline process that had been developed a few decades ago by the University of Akron, OH, under contract to the quasi-governmental Electric Power Research Institute, "EPRI", of Palo Alto, California, as a part of EPRI's "Fuel Science Program".
Back then, while we were still young and naive, we labored under the idealistic misperception that, if we were just able to alert our Coal Country press corps, half a dozen members of which are the primary addressees of these reports, by the way, to the facts, that, yes, both Coal and Carbon Dioxide can be converted into liquid hydrocarbon fuels, domestic United States replacements for anything we now allow ourselves to be extorted by the alien nations of OPEC to keep ourselves supplied with in the here and now, then, those members of the Coal Country press corps would jump in and lend their professional research and compositional skills to the "cause".
We, of course, badly, and obviously, misjudged back then both the patriotism and the personal loyalties of our Coal Country press corps addressees. Older, and very sadly wiser, now, we find ourselves compelled to revisit the University of Akron's Coal-to-Gasoline technology, with some additional information and a fuller exposition of what their development was all about.
First, we remind you of one of our reports concerning the University of Akron, as accessible via:
West Virginia Coal Association | U of Akron: Methanol-to-Gasoline vs. DME-to-Gasoline | Research & Development; concerning: "Methanol-to-gasoline vs. DME-to-gasoline. II: Process comparison and analysis; Sunggyu Lee, et. al., University of Akron, Department of Chemical Engineering, OH; 1995; Abstract: Methanol can be converted into gasoline boiling range hydrocarbons over zeolite ZSM-5 catalyst using the Mobil MTG process. Methanol feed in the MTG process can be derived from coal ... . The Mobil MTG process involves the conversion steps of syngas-to-methanol and methanol-to-gasoline. Dimethyl Ether (DME), a product of methanol dehydrocondensation, is an intermediate species in the methanol-to-gasoline conversion. Syngas can be directly converted to DME using the Liquid Phase Dimethyl Ether Synthesis (LP-DME) process developed at the University of Akron in conjunction with Electric Power Research Institute. This direct one-step conversion of syngas-to-DME can then be an ideal front end for further conversion to gasoline. This substitution (syngas-to-methanol by syngas-to-DME) is justified because DME results in an identical hydrocarbon distribution over the ZSM-5 catalyst as methanol. The DME-to-Gasoline (DTG) process thus involves the conversion steps of syngas-to-DME and DME-to gasoline. The UA/EPRI DTG process offers advantages over the Mobil MTG process in several areas. These include heat duty and heat of reaction, adiabatic temperature rise, hydrocarbon product yield and selectivity, syngas conversion, and overall process efficiency. The conceptual benefits of the DTG process have been demonstrated experimentally in a fluidized bed reactor system operative at the University of Akron. The salient features of the DTG process and process comparison to the Mobil MTG process are discussed in this paper".
And, we note that we have reported on the above "Mobil MTG", now more appropriately ExxonMobil, "methanol-to-gasoline", "process" numerous times, as in, for just two examples:
West Virginia Coal Association | ExxonMobil Coal to Methanol to Gasoline | Research & Development; concerning both: "United States Patent 4,348,486 - Production of Methanol via Catalytic Coal Gasification; 1982; Assignee: Exxon Research and Engineering Company, NJ; This invention provides a process for producing methanol by the substantially thermoneutral reaction of steam with coal"; and: "United States Patent 4,035,430 - Conversion of Methanol to Gasoline; 1977; Assignee: Mobil Oil Corporation, NY; This invention relates to the method and system for converting methanol to gasoline boiling components"; and:
West Virginia Coal Association | ExxonMobil "Coal to Clean Gasoline" | Research & Development; concerning: "Coal to Clean Gasoline; ExxonMobil Research and Engineering Company; ExxonMobil's methanol to gasoline technology for the production of clean gasoline from coal. ExxonMobil’s methanol-to-gasoline (MTG) process efficiently converts crude methanol to high quality clean gasoline. When coupled with commercially proven coal gasification and methanol synthesis technology, MTG offers an effective route to premium transportation fuel from coal".
The thrust of the University of Akron's research, however, was the use of Dimethyl Ether, DME, rather than Methanol, as the intermediate between "Coal" and "Gasoline", with DME being just a "deoxygenated" version of the Methanol molecule, one of many alcohols, like Ethanol, of course, which are sometimes referred to as "oxygenated hydrocarbons".
As we've noted in other of our reports, such as:
West Virginia Coal Association | Southern California Recycles More CO2 | Research & Development; concerning, in part: "United States Patent 7,608,743 - Efficient and Selective Chemical Recycling of Carbon Dioxide to Methanol, Dimethyl Ether and Derived Products; 2009; Assignee: The University of Southern California; Abstract: An efficient and environmentally beneficial method of recycling and producing methanol from varied sources of carbon dioxide including flue gases of fossil fuel burning powerplants, industrial exhaust gases or the atmosphere itself. Converting carbon dioxide by chemical or electrochemical reduction secondary treatment to produce essentially methanol, dimethyl ether and derived products";
and, as can be learned separately in:
Green Car Congress: China to Support Development of Dimethyl Ether as Diesel Alternative; "The Chinese government will support the development of dimethyl ether (DME), a gas derived from coal, as a possible alternative to diesel. A circular from the National Development and Reform Commission (NDRC) said standards for the use of DME as a civil fuel were being drawn up. DME is an LPG-like synthetic fuel that is produced through gasification of coal or various renewable substances. The synthetic gas is then catalyzed to produce DME. A gas under normal pressure and temperature, DME can be compressed into a liquid and used as an alternative to diesel. Its low emissions make it relatively environmentally friendly";
Dimethyl Ether is a versatile hydrocarbon, which, though gaseous at standard conditions of temperature and pressure, condenses easily into a liquid and can be utilized directly as a very clean-burning substitute for both Liquefied Petroleum Gas, LPG, and, with some apparently minor modifications of the fuel handling and engine management systems, plain old Diesel fuel.
However, just like Methanol in ExxonMobil's "MTG"(r), methanol-to-gasoline, process, Dimethyl Ether, whether made from Coal or, as in our above citation of "United States Patent 7,608,743 - Efficient and Selective Chemical Recycling of Carbon Dioxide to Methanol, Dimethyl Ether and Derived Products", from Carbon Dioxide, can be converted rather directly into Gasoline. And, it might be more efficient to, first, manufacture Dimethyl Ether and then convert it into Gasoline, rather than, as implied by ExxonMobil, to first convert Coal or Carbon Dioxide into Methanol, and then convert the Methanol into Gasoline.
And, that, really, seems to be the thrust of the additional research performed by the University of Akron, as funded by EPRI, subsequent to or coincident with that seen in our above-cited report concerning "Methanol-to-gasoline vs. DME-to-gasoline. II: Process comparison and analysis". We regret that vagueness, but, unfortunately, we haven't yet mastered the intricacies of the EPRI library's catalog system, and have to run with things pretty much as we find them.
That said, comment follows excerpts from the initial link in this dispatch to:
"'A Novel Synthesis Route for Liquid Fuels from Coal-derived Syngas'
Makarand Gogate, Conrad J. Kulik, and Sunggyu Lee; Department of Chemical Engineering; The University of Akron, Akron, Ohio
Fuel Science Program; Electric Power Research Institute; Palo Alto, California
Abstract: Coal-derived syngas can be converted to methanol using Liquid Phase Methanol Synthesis Process. Methanol can be further converted to gasoline using the Mobil Methanol-To-Gasoline (MTG) process. The combination of commercial syngas-to-methanol technology with the MTG Process thus provides a ready synthetic route for liquid hydrocarbon fuels.
We have developed a novel process for one-step synthesis of Dimethyl Ether (DME) from syngas. This DME Synthesis improves the reactor productivity and syngas conversion, by as much as 100% over LPMeOH (Liquid Phase Methanol) Process.
One-step DME synthesis is thus an ideal front-end for further conversion to gasoline.
This substitution is justified not only because DME yields an identical product distribution as methanol, DME is also a true intermediate in the Mobil MTG process. The novel integration scheme has been termed as the Dimethyl Ether-to-Gasoline (DTG) process. The advantages of the UAEPRI (University of Akron and Electric Power Research Institute) DTG Process over the conventional Methanol-to-Gasoline Process are in:
(a) enhanced syngas conversion,
(b) superior hydrocarbon yield,
(c) superior product selectivity,
(d) alleviated heat duties, and:
(e) integrated energy efficiency.
Introduction: The conversion of syngas to gasoline occurs typically in two stages. Syngas is first converted to methanol over a copper-based hydrogenation catalyst. In the second stage, methanol is converted to
gasoline over a ZSM-5 catalyst.
These two process steps form the basis for the Mobil Methanol-To-Gasoline (MTG) Process. Dimethyl Ether (DME) is a key intermediate chemical species in the second stage. Mobil's MTG process in combination with the commercial syngas to methanol technology thus provide a ready route to synthetic gasoline.
The first stage of the MTG process is the synthesis of methanol from syngas. In a typical Liquid Phase
Methanol Synthesis (LPMeOHTM) process, the synthesis catalyst (composed of CuO, ZnO, and Al203)
is slurried in an inert hydrocarbon oil. Syngas (H2, CO, and CO2) reacts over the active catalyst to produce methanol in-situ.
The reaction chemistry for methanol synthesis ... has been well-established:
CO2 + 3 H2 = CH3OH + H2O.
Syngas-to-methanol conversion technology has recently been modified and improved to synthesize
Dimethyl Ether (DME) directly from syngas in a single reactor stage. This process augments
the per-pass syngas conversion and volumetric reactor productivity as a result of reduced chemical
equilibrium limitation governing the syngas-to-DME conversion.
In the Liquid Phase DME Synthesis (LP-DME) process, DME is thus directly produced from syngas, in
a single reactor stage.
The LP-DME synthesis is ... based on the application of dual catalysis in the liquid phase (and) can be an effective substitute for the syngas-to-methanol step in the Mobil MTG Process. This substitution is justified based on the following facts
(a) DME results in virtually identical hydrocarbon product distribution as methanol, and:
(b) DME is a true intermediate in the Mobil MTG process.
The single-stage conversion of syngas to DME ... thus provides an ideal front-end for further conversion to gasoline. A novel syngas-to-gasoline process based on this unique integration scheme (Syngas-to-DME and DME-to-Gasoline) has been proven to be superior to the Mobil MTG process.
Our novel synthesis process for hydrocarbon fuels has been termed as the UNEPRI Dimethyl Ether -To- Gasoline (DTG) process. The DTG process merits over the Mobil MTG are in the areas of heat duty, heat of reaction. adiabatic temperature rise, space time and velocity, reactor size, hydrocarbon product yield, and selectivity.
Results and Discussion: The conversion of methanol to hydrocarbons is an exothermic reaction. Depending on the nature and spectrum of the hydrocarbon product, the heat of reaction will vary.
Based on (illustrated and described) calculations ... the heat of reaction for DME conversion to hydrocarbons was found to be 32% less than that for methanol conversion to hydrocarbons. Overall, since methanol dehydration to DME contributes about 25% to the total heat of reaction of the methanol conversion to hydrocarbons, it is expected that the heat of reaction for DME conversion to hydrocarbons at complete conversion would be about 25% lower than that for methanol conversion.
The conversion of methanol to water and hydrocarbons is essentially stoichiometric and complete. Water is the only co-product.
.
For the conversion of DME to hydrocarbons and water (the) selectivity towards (is greater, and the) reactor productivity would then be ... 38% higher for the DME conversion.
The conclusive advantages of this novel synthesis route (are summarized in accompanying data).
One-step conversion of syngas to DME improves the per-pass syngas conversion and reactor productivity over syngas to methanol.
The conversion of syngas to methanol uses copper-based Cu/ZnO/A1203 catalyst. This catalyst is
susceptible to deactivation by crystal growth in the liquid phase rich in methanol and water. However,
the conversion of syngas to DME uses a dual catalyst system based on a combination of Cu/ZnO/Al203
catalyst and gamma-alumina catalyst. (The advantages are described.)
The conversion of methanol and DME to hydrocarbons is a function of space velocity (or, space time in
the reactor). The reaction paths for methanol and DME conversion bring out this fact in greater
detail. (For) identical MTG and Dimethyl Ether To Gasoline (DTG) reactor size, the DTG reactor will be 25% more productive (i.e., reactor productivity per unit volume) than the MTG reactor.
One-step conversion of syngas to DME improves the per-pass syngas conversion and reactor productivity over syngas to methanol.
The one-step conversion of syngas to DME improves the volumetric reactor productivity by as much as 100% over that of syngas to methanol conversion. This is because of conversion of syngas to DME is not nearly limited by chemical equilibrium as syngas to methanol. This fact has been well proven by the research at the University of Akron.
Process comparison and analysis of Syngas-to-Methanol-to-Gasoline and Syngas-to-DME-to-Gasoline
conclusively proves that synthesis of gasoline via direct DME route has definitive process advantages
over the synthesis via methanol route. These process merits are in the areas of higher gasoline yield,
higher syngas conversion, good adaptability to coal-based syngas, and integrated energy efficiency.
This work was completely supported by the Electric Power Research Institute, via the research contract
RP317-6."
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We'll continue to research this issue, to see if it went any further. Likely not, except in China, even though, as seen for yet another example, in our report of:
West Virginia Coal Association | Conoco Converts Coal to Methanol and Dimethyl Ether | Research & Development; concerning: "United States Patent 6,638,892 - Syngas Conversion and Catalyst Employed Therefor; 2003; Assignee: ConocoPhillips Company, Houston; Abstract: A process for the conversion of syngas by contact of syngas under conversion conditions with catalyst having as components zinc oxide, copper oxide, aluminum oxide, ... zeolite and clay in ... a one step process for conversion of syngas to dimethyl ether (and) a two step process for conversion of syngas to light olefins ... . Dimethyl ether is a clean and efficient alternative diesel fuel which can be produced by the dehydration of methanol which can be synthesized from syngas. There is a significant economic advantage in integrating the process for producing dimethyl ether from syngas into a single process. Syngas has proved to be an attractive source from which light olefins can be obtained. Synthesis gas (syngas) is a gaseous mixture of hydrogen and at least one carbon oxide, particularly carbon monoxide. Syngas is obtained using well known processes by the partial combustion or gasification of any organic material such as coal ... . It is well known that Syngas can be subjected to a heterogeneous catalytic reaction using a copper-based catalyst such as copper oxide, zinc oxide and aluminum oxide to produce methanol. This is the same catalyst that is used in this invention along with ... zeolite ... to produce dimethyl ether";
the United States petroleum industry knows full well that Coal-derived synthesis gas, "syngas", can, as affirmed herein by the University of Akron and the Electric Power Research Institute, be efficiently converted into just such "a clean and efficient alternative diesel fuel"; an "alternative diesel fuel", which also, via the "UNEPRI Dimethyl Ether -To- Gasoline (DTG) process" also discussed herein, be further efficiently converted into the just as desperately-needed liquid fuel, Gasoline.