CO2 and Fuel from Air

 
First of all, as we understand online references we've accessed, "silanes" are relatively common industrial chemicals, encompassing a range of formulas. But, they are, basically, the silicon-hydrogen counterparts of carbon-hydrogen compounds such as methane. The technicalities are far beyond us, but it seems they can be made by, essentially, reacting commodity hydrochloric acid with a variety of abundant silicon-containing minerals. Beach sand is a common silicon-containing mineral, but we've no idea if it's inertness would allow it to be a feasible raw material, or not.
 
But: Silicon is as common as, literally, dirt; and, hydrochloric acid is nearly so.
 
In any case, once you've made silane, or bought it from one of it's multiple major industrial suppliers, you can collect some Carbon Dioxide and make the gasoline and plastics raw material, Methanol, out of it.
 
As per the excerpt, comment appended:
 
"Conversion of Carbon Dioxide into Methanol with Silanes over N-Heterocyclic Carbene Catalysts
 
Siti Nurhanna Riduan, Yugen Zhanj, Dr. Jackie Y. Ying; Inst. of Bioengineering; Singapore
 
Abstract: Carbon Dioxide was reduced with silane using a stable organocatalyst to provide methanol under very mild conditions. Dry air can serve as feedstock, and the organocatalyst is much more efficient than transition metal catalysts for this reaction. This approach offers a very promising protocol for chemical CO2 activation and fixation."
 
There are multiple items of import to be gleaned from our sparse extract of the abstract. And, we're compelled to oversimplify them, thus: With a product you can, in essence, make from beach sand and stomach acid, you can make liquid fuel, "methanol", out of "dry air".
 
Left unstated is that this is a productive recycling of Carbon Dioxide, as opposed to an expensive, and deceptive, "disposal" of it. Also unstated are the possibilities of siting such an operation at the business end of a coal plant's smokestack, where the CO2 would be more concentrated, and waste heat would be available to help drive the process.
 
And, note: We have cited these researchers, and/or their colleagues, in small and isolated Singapore, previously, on the subject of true Carbon Dioxide utilization. They are at work figuring out how to do the best they can with what they have to work with. In their case, it's "dry air".
 
We are blessed with abundant coal and concentrated smoke stack emissions.
 

Cure for CO2 Headache

 
We've thoroughly documented that the Carbon Dioxide by-product of our coal use could, and should, be viewed as a useful, even valuable, resource from which we can manufacture more liquid fuels, and raw materials for our plastics and chemicals industries.
 
As the enclosed report, from collaborating researchers in both Spain and Japan, reveals, there are multiple technical ways in which the relatively inert CO2 can be processed, made more reactive, so that the carbon it contains can be utilized in the synthesis of valuable products, even medicine.
 
We have edited our excerpt in the extreme. Like much of what we send you, the complete information begs reading by competent individuals able to bring the information to the attention of those who most deserve to learn of it: The citizens of the United States, and most especially those citizens resident in US Coal Country.
 
The excerpt: 
 
"Electrochemical approaches to alleviation of the problem of carbon dioxide accumulation
 
C. M. Sánchez-Sánchez, V. Montiel, D. A. Tryk, A. Aldaz, and A. Fujishima

Grupo Electroquímica Aplicada, Departamento de Química Física, Universidad de Alicante, Ap. 99, E-03080, Alicante, Spain
 
Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
 
Abstract: The electrochemical reduction of CO2, which includes a number of different specific approaches, may show promise as a means to help slow down the accumulation of this greenhouse gas in the atmosphere. Two types of approaches are examined briefly here. First, CO2 can be used as a reagent in the electrocarboxylation reaction to produce organic carboxylic acids, for example, the pharmaceutical ibuprofen. Second, CO2 can be converted to a fuel, either directly or via synthesis gas. The latter can be produced with reasonably good energy efficiency in a gas-diffusion, electrode-based cell even at present with existing electrocatalysts. Oxygen gas is produced as a by-product. Further work is needed to improve the selectivity and efficiency in this and other approaches.
 
Chemists have been working on various ways to prevent the accumulation of atmospheric CO2, including removal, sequestration, utilization, and conversion into fuels [1]. In particular, electrochemical researchers have been making sizable efforts to develop ways to transform CO2 into useful substances such as fuels or chemicals. The past decade or two have seen the growth of the subject, with promising results of electrochemical approaches.
 
This report tries to portray some of the principal electrochemical approaches to the CO2 problem that have been proposed by various research groups. We begin by explaining two generic electrochemical methods of utilizing CO2. The first involves the coupling of CO2 to electrochemically reduced organic molecules (electrocarboxylation), with the goal being to find new routes to synthesize chemicals that are interesting from a pharmacological point of view. The second is the direct electrochemical reduction of CO2, with the goal being to obtain hydrocarbons, alcohols, or other fuels. This second method can in turn be divided into two groups, according to whether metals or transition-metal complexes are used as catalysts."
 
(These scientists, like many we cite for you in our reports, are compelled to use, in places, highly-technical language, and we don't, because of our own limitations and lack of understanding, excerpt much of it directly for you. But, two things in the foregoing are quite clear, are stated categorically by these scientists: "CO2 can be used ... to produce ... organic carboxylic acids (like) ibuprofen. Second, CO2 can be converted to a fuel." That message comes through quite clearly. We wonder when everyone will start receiving it. - JtM) 
 
"The utilization of CO2 in the carboxylation of various types of organic compounds has been known for many years....
 
Electrochemical reductive carboxylations have been described for a large number of substrate types, including ketones, acetylenes, olefins, alkyl halides, and heterocyclic compounds. However, the most important scale-up processes are related to the synthesis of nonsteriodal antiinflammatory drugs (NSAIDs).
 
Direct electrochemical approaches to convert CO2 to various types of fuels have been investigated for several decades. ... Moreover, the reduction of carbon dioxide in the potentials at which the cathodic reaction occurs is normally accompanied by hydrogen evolution."
 
(So, "reduction of carbon dioxide" is "normally accompanied by hydrogen evolution". If we are blessed to receive both Carbon and Hydrogen, what can be made of them? Hydrocarbons? - JtM)  
 
Investigations on the direct electrochemical reduction of CO2 can be categorized into two groups according to the type of catalytic system:
 
1. Heterogeneous catalytic systems using cathodes of bulk or particulate metals, which show particular selective product properties. Their general properties are long-term reliability and acceptable mechanical, thermal, and chemical stability.

2. Homogeneous and heterogeneous catalytic systems using transition-metal complexes as catalysts. Attractive features are high selectivity and low operating potentials, but at the price of limited stability.
 
These catalytic systems ... carry out the electrochemical reduction of CO2, ... (and) ... In aqueous solution, C1-type compounds (e.g., carbon monoxide, formic acid, methanol, methane) are produced."
 
(If we get carbon monoxide, we can use it in processes, like Fischer-Tropsch synthesis, to make liquid fuels. Formic acid, among other uses, can be employed in fuel cells. Methanol is a valuable liquid fuel in it's own right, but can serve as a raw material from which we can make gasoline and plastics. Methane can be used in it's traditional role as "natural gas", or, like methanol, be employed in the synthesis of other valuable organic chemicals. - JtM)
 
"In the case of aqueous media, metal electrodes used in the electroreduction of CO2 can be divided in different groups according to the nature of the main product.
 
A. Hydrocarbons and alcohols (Cu).
B. Carbon monoxide (Au, Ag, Zn, Pd, and Ga).
C. Formic acid (Pb, Hg, In, Sn, Bi, Cd, and Tl). 
 
Shibata and coworkers have developed an important line of research involving the electrochemical synthesis of urea by simultaneous reduction of CO2 and nitrite or nitrate ... .
 
... various compositions of synthesis gas can be produced. ... useful to synthesize methanol ... .  
 
It is, of course, necessary to compare such an electrochemical method for producing synthesis gas with purely chemical ones such as steam reforming of methane or partial oxidation of methane, which is used in industry as a method of producing synthesis gas, and carbon dioxide reforming of methane. Although the electrochemical route costs more energy, this is because it includes the energy cost of producing the hydrogen.
 
It appears possible that the electrochemical reduction of CO2 could be applied to new energy storage systems that could contribute to the alleviation of the accumulation of atmospheric CO2. As one example, CO2 reduction shows great potential in the production of pharmaceuticals and fine chemicals. ...  A second example is the reduction of CO2 to produce fuels or synthesis gas."
 
----------
 
Multiple options exist, it seems, to make valuable, profitable, use of coal's major by-product. Further comment from us, at this point, seems pointless. We'll close by noting the Spanish and Japanese authors include a very substantial reference list, which confirms even further that the science of CO2 utilization, like the science for converting coal into liquid fuels, is, in certain circles, well-known and well-understood. What isn't known or understood, at all, by us, is why those sciences haven't been publicized and explained to the people who most deserve to have that knowledge; the people who could and would do the most with it: The citizens of the United States of America, and, most especially, those citizens resident in US Coal Country.

CO2 Recycling Proposal

 
Since we've lately aroused some ire with our demeaning of the deceptive concept of Geologic Sequestration as a means to "abate" our Carbon Dioxide "problem", we thought everyone might be interested in a what a US Government Geologist thinks we coal people ought to do with our offensive gas.
 
The revealing excerpt, containing some preamble, comment interspersed and appended, with the full document attached and available via the enclosed link:
 
"Reductive Sequestration of Carbon Dioxide
 
T. Mill
SRI
333 Ravenswood
Menlo Park, CA 94025

D. Ross 
U.S. Geological Survey, Bldg 15 MS 999
345 Middlefield Rd.
Menlo Park, CA 94025

The United States currently meets 80% of its energy needs by burning fossil fuels to form CO2. The combustion-based production of CO2 has evolved into a major environmental challenge that extends beyond national borders and the issue has become as politically charged as it is technologically demanding.
 
(A lot of political charges are involved, it would seem - even more than immediately meet the eye, based on our recent experiences. - JtM)
 
Whereas CO2 levels in the atmosphere had remained stable over the 10,000 years preceeding the industrial revolution, that event initiated rapid growth in CO2 levels over the past 150 years (Stevens, 2000). The resulting accelerating accumulation of CO2 in the troposphere is increasingly linked to global climate-warming, with projections of continued warming in the absence of resolute changes in CO2 management (Revkin, 2000).
 
The worldwide effects of warming on forestry, fresh water supplies, farming, coastal stability, and human health could be enormous. In response to these threats, the 1997 Kyoto Treaty on Global Warming was initiated in a major world-wide effort to curtail CO2 emissions. A major feature of this activity involves separation, collection and storage of a significant fraction of the 6-billion tons of CO2 currently produced worldwide each year. The annual U.S. production is about a third of that value, and sites considered for storing U.S. produced CO2 include depleted gas reservoirs, deep saline aquifers, depleted oil reservoirs, coal beds, and the deep ocean (Noserale, 1999).
 
(After those obligatory genuflections to speculative fears, the authors start getting to the meat of it. The following concepts need far more serious public consideration than they have so far received. - JtM)
 
Although accumulating the captured gas in vast reservoirs seems a rational approach to the problem, a second, potentially more rewarding route is suggested here. Because the nominal 2 billion tons of CO2 the U.S. produces annually represents the energy content of about 11 million barrels of oil per day, or roughly the U.S. daily import (Feld, 2000), we propose that CO2 be considered a renewable resource. We propose specifically that it be recycled back to fuel by employing water as the hydrogen source, and the reductive chemical energy available from sunlight driven electron/hole production, or thermal reduction using abundant Fe[II]-containing minerals.
 
(Note how carefully they approach this topic: "Although accumulating the captured gas in vast reservoirs seems a rational approach to the problem, a second, potentially more rewarding route is suggested here." Really. Does attempting to accumulate "the captured gas in vast reservoirs", at some great expense, really seem "a rational approach" to anyone? Especially since, as we've earlier documented, those "vast reservoirs" are pretty darned leaky? - JtM) 
 
If the process (of converting CO2 to hydrocarbons - JtM) can be successfully applied, it would not only satisfy concerns tied to global warming, but would also eliminate some fraction of the nation’s daily dependence on imported oil. This dependence is now a matter of renewed concern and uneasiness with impact on both national security and the economy (Ebel, 2000; New York Times, 2001).
 
(Understatement seems these authors' style. - JtM)
 
The proposed process involves reductive capture of CO2 in a two-part scheme related in part to the Fischer Tropsch process, and employing common minerals with sufficient reduction and/or photoreduction potential to convert CO2 to formate and/or methanol (Yoneyama, 1997) and then to fuel-valued products. Thermochemical calculations show the overall scheme to be highly exothermic, and thus self-sustaining with the proper process design.
 
(Note: Their concept is "related in part to the Fischer Tropsch process" wherein, as all our readers should by now know, gasses, including CO2, are generated from coal, and then condensed, via catalysis, into hydrocarbon liquids. And, they point out a fact that we have earlier documented for you: A portion of the reaction process of converting Carbon Dioxide into useful hydrocarbons is "highly exothermic, and thus self-sustaining. The need for external energy inputs to drive the conversion is reduced, with corresponding reductions, we are led to presume, in the overall cost. - JtM)
 
Objectives
 
This paper explores the photochemical and thermochemical parameters associated with reduction of CO2 to C1 products and their subsequent conversion to alkanes and proposes a program to assess the key kinetic steps required to effect reduction to methane and higher alkanes. With that information, the overall feasibility of using this process for sequestration of CO2 can be evaluated relative to other CO2 sequestration
processes.
 
(For emphasis: These authors are presenting details on the efficient "reduction of CO2 to C1 products and their subsequent conversion to alkanes". Easily accessible web references will tell you that gasoline is a mixture of hydrocarbons, and most of those hydrocarbons are "alkanes". These authors are telling us, without, we suspect deliberately using the word, that we can, through efficient catalytic processes, convert Carbon Dioxide into Gasoline. - JtM)
 
Carbon dioxide and its aqueous counterparts, bicarbonate and carbonate, are inherently highly stable.
 
Recently, however, the possibility of large-scale, process-level CO2 reduction has become more viable following two separate published accounts describing the reduction of CO2 with common minerals. The first is a report by McCollom (2000) who discussed experiments in hydrothermal media with dissolved CO2 and the mineral olivine, which showed that bicarbonate ion was immediately reduced to formate at 300°C and 350 bar. These conditions are at pressures above the water saturation curve and therefore there was no headspace in the reactor. McCollom suggested that absence of headspace stopped the reduction at formate, since further reduction to alkanes is highly favored thermodynamically.
 
McCollom et al. (1999) confirmed this speculation in other work using a system purposefully containing a headspace, in which reduction of aqueous formate to a broad array of hydrogen-rich Fischer Tropsch-like products in the C2 - C35 range, including alkanes, alkenes, and oxygenated products, readily took place at 175°C. In the absence of headspace, formic acid is in solution, where it is mostly ionized to the stable formate ion. When headspace is available, further reduction occurs can in the gas phase through the molecular acid, most probably on the reactor surfaces. 
 
("Formate", made from CO2, can be chemically reduced into "hydrogen-rich Fischer Tropsch-like products", just as coal can be processed via Fischer-Tropsch technology, as we've more than thoroughly documented, to manufacture liquid hydrocarbon fuels. - JtM)
 
The second account of a mineral-based conversion describes sunlight-driven production of formic acid from CO2 at ambient temperatures. In this case, Ohta et al. (2000) worked with a selection of common Iron containing silicate rocks (amphibolite, granite, gneiss, shale) which were powdered and suspended in CO2-saturated water. When the mixtures were irradiated by sunlight at ambient temperatures, formic acid was formed at a rate of several µgm/m2 over 18 hours. No evidence was found for further reduction to other acids or hydrocarbons. Ohta et al. report no effort, however, to identify the specific metal oxide(s) responsible for reduction of CO2, nor to determine the photoefficiency of the process.
 
(Note: Some minerals can catalyze the conversion of CO2 into formic acid at "ambient temperature", that is, with little additional energy input. The formic acid, formate, as reported above, can then be converted into "alkanes" - the primary constituents of gasoline. - JtM)
 
Photoreduction of CO2 on irradiated semiconductor surfaces has been widely reported to give a range of C1 and C2 products, including CO, formate, methanol, methane, formaldehyde, oxalic acid and glyoxal (Yoneyama, 1997). CO2 photoreductions are observed on a variety of metal oxides, including WO3, TiO2, ZnO, as well as on GaP. ZnS and CdS. Reductions are believed to result from photopromotion of hole/electron pairs in the oxide/sufide conduction bands, capture of electrons by CO2 and hole oxidation of water or some added reducing agent. Photoefficiencies for CO2 reduction appear to range from less than 1% to 23% on certain quantized oxide particles (Yoneyama, 1997; Inoue et al, 1990). The high efficiencies also appear to require large band gaps, thus reducing efficient use of the full spectrum of sunlight.
 
The existing literature on CO2 reductions shows that the reactions do work and can be modified to produce varying proportions of C1 and C2 products. However, efficiencies vary widely and the factors controlling selectivity and band gap energies are not well understood. Nor is it clear how the work of Ohta et al. with ferrous minerals relates to the semiconductor oxide processes. Despite these important gaps in understanding these two reduction processes, we propose a scheme to create fuel-valued products from process CO2. ... The hydrogen source is water in the feed mixture. 
 
(As we've reported from other research: Hydrogen is needed for hydrogenation, and the "hydrogen source is water in the feed mixture", a point we've made several times in the earlier citations. - JtM)
 
Conversions of CO2 are highly exothermic, with the production of methane being the most heat-yielding. Thus, a self-sustaining operation should be attainable with the proper process design.
 
(Again, "a self-sustaining operation" to recycle CO2 into valuable hydrocarbons, because the reaction sequence is "highly exothermic", "should be attainable". - JtM)
 
In summary, it appears that the practical sequestration of CO2 through conversion to formic acid and fuel-valued materials is feasible. The sensible utilization of the concept will depend on the balance between the fuel value provided by reduction of CO2 and the energy requirements for reduction. The energy requirements are directly tied to the basic thermochemistry and kinetics of the individual steps in the sequence, including the two thermal and one photochemical step. The program proposed here is designed to develop the necessary  kinetic and photochemical parameters to evaluate the commercial potential of CO2 recycling.
Because of the fundamental nature of the study, the results should also serve as a significant contribution to the chemical literature.  
 
A research program to evaluate key kinetic and photochemical steps will be conducted over 24 months in which work will be conducted concurrently on the photo- and thermal-reduction processes to allow a direct comparison of their features. Several of the minerals described by Ohta et al. (2000) will be used with near uv light for the initial measurements of CO2 conversion to formate to confirm their observations. Purified semiconductor oxide components of the minerals will be examined under the same conditions of light intensity, wavelength and particle size to identify the most likely mineral constituents responsible for CO2
reduction to formate. Band gaps and photoefficiencies of several minerals for reduction of CO2 will be measured as a function of particle size and the results used to optimize a photoreactor design with practical value.
 
The ultimate product of the program will be a detailed understanding of the reaction fundamentals of the multistep process. The database will be suitable for a sound appraisal of the conversion concept, and an evaluation of the prospect of advancing to a process development study."
 
---------
 
Following are a selection from the authors' reference list. Brief review suggests there might be some interesting reading available for anyone genuinely interested in a productive and profitable alternative to the geologic sequestration squandering of a potentially valuable by-product of our coal use industries.
  
References
 
Berndt, M. E., D. E. Allen, and W. E. Seyfried, Jr. (1996). Reduction of CO2 during serpentinization of olivine at 300°C and 500 bar. Geology 24, 351-354.
 
Ebel, R. E. (2000). “Comments on the economic and security implications of recent developments in the world oil market.” Presented before the United States Senate Committee on Governmental Affairs, March 24.
 
Inoue, H., T. Torimoto, T. Sakata, H. Mori, and H. Yoneyama (1990). Photoreduction of carbon dioxide on quantized zinc sulfide. Chem. Lett. 1483-1486.
 
McCollom, T. M. (2000). Reduction of aqueous CO2 to organic compounds at hydrothermal conditions: Does it work? Presented at the First Astrobiology Science Conference, Ames Research Center, Mountain View, California, April 2-5.
 
McCollom, T. M., G. Ritter, and B.R.T. Simoneit (1999). Lipid synthesis under hydrothermal conditions by Fischer-Tropsch-type reactions. Origins of Life and Evol. of the Biosphere 29, 153-166.
 
Ohta, K., H. Ogawa, and T. Mizuno (2000). Abiological formation of formic acid on rocks in nature. Applied Geochemistry 15, 91-95. 
 
Yoneyama, H. (1997). Photoreduction of carbon dioxide on quantized semiconductor nano particles in solution. Catalysis Today 39: 169-175.

Penn State Improves Coal LIquefaction

 
We've previously documented the work of Penn State University in the development of carbon conversion technology. Herein, it's reported that they have improved the process of making the liquid fuels we need from our abundant coal by, simply, adding water.
 
Brief comment follows:
 
"A new process for catalytic liquefaction of coal using dispersed MoS2 catalyst generated in situ with added H2O
 
C. Song, A.K. Saini and Y. Yoneyama
 
Applied Catalysis in Energy Laboratory, The Energy Institute, Pennsylvania State University, 209 Academic Projects Building, University Park, PA 16802, USA

Department of Energy and Geo-Environmental Engineering, Pennsylvania State University, 206 Hosler Building, University Park, PA 16802, USA

December 1999.

Abstract

We have found that adding a proper amount of water can dramatically improve conversion of a sub-bituminous coal in solvent-free liquefaction under at 350C using ammonium tetrathiomolybdate (ATTM) as precursor to dispersed MoS2 catalyst H2 pressure. However, adding water to catalytic reactions at 400C decreased coal conversion, although water addition to the non-catalytic runs was slightly beneficial at this temperature. We further examined the effect of water in solvent-mediated runs in addition to “dry” tests and explored a temperature-programmed liquefaction (TPL) procedure to take advantage of the synergetic effect between water and dispersed Mo catalyst precursor at low temperatures for more efficient coal conversion. The TPL using ATTM with added water at 350C, followed by water removal and subsequent reaction at 400C gave good coal conversion and oil yield. Model reactions of dinaphthyl ether (DNE) were also carried out to clarify the effect of water. Addition of water to ATTM substantially enhanced DNE conversion at 350C. The combination of data from one-step and two-step tests of DNE and coal at 350–400C revealed that water results in highly active MoS2 catalyst in situ generated at 350C, but water does not promote the catalytic function or reaction once an active catalyst is generated. Using ATTM coupled with water addition and removal and temperature-programming may be an effective strategy for developing a better coal conversion process using dispersed catalysts."

We have cited Dr. Song, and others at Penn State, in a few of our previous dispatches. And, we have referenced for you other work indicating that plain old water, for various reasons, could enhance the efficiency and productivity of coal liquefaction processes. We've submitted this piece, like others recently, to help demonstrate that, unlike what some would have us believe, the science and technology to convert our abundant coal into liquid fuels doesn't just exist, but, it is, in some circles, well-known, well-understood and undergoing continuous improvement.

Our question: Just how good does it, coal-to-liquid conversion technology, have to be before we stop allowing ourselves to be extorted for overseas oil? Before we stop allowing our domestic economy to be further weakened and crippled? Before we put all of our people to work? Before we establish a self-sufficient US domestic energy economy based on coal; and, on the recycling of coal-use by-products, including CO2?

It's now obvious the technology to accomplish all of that is available. But, why we aren't now using that technology sure ain't so obvious.

Germany Improves Coal Liquefaction

 
We have thoroughly documented that Methanol can be extracted from coal, and from carbon-recycling cellulose; and, as in Sabatier reactions, it can be synthesized from Carbon Dioxide, via methane.
 
We have also documented that, once obtained, Methanol can be further converted into gasoline, and a variety of organic chemicals useful as raw materials in the manufacture of plastics. One such notable technology, about which we have reported, is ExxonMobil's "MTG"(R), methanol-to-gasoline, process.
 
We have also reported on the coal gasification technology available from Germany's Lurgi AG, and it's applicability to commercial coal conversion industries.
 
Herein, according to Volkswagen, Lurgi has put the technologies together and developed it's own, "MTS", or "MtSynfuels"(R), methanol-to-synfuels, process.
 
Some excerpts: 
 
"MtSynfuels Process
 
Lurgi AG develops a process called MTSynfuels(R) (Methanol-to-Synfuels). Like Fischer-Tropsch-Processes (FT), the process is designed to produce liquid fuels from synthetic gases.
 
("Fischer-Tropsch" should by now be familiar to all our readers; and, the "synthetic gases" would, it should now go without saying, but say it we will, be produced from coal, among other things.)

The production of syngas and the synthesis of methanol

Like the FT process, syngas is the starting material for the MtSynfuels(R) process, which can be produced from various fossil fuels and renewable raw materials. The syngas must meet the same purity requirements and have the same composition (i.e. H2/CO = 2) as is usual for FT synthesis. The subsequent conversion of syngas to methanol is exothermic, as in the following reactions:

CO + 2 H2 –> CH3OH

CO2 + 3 H2 –> CH3OH + H2O

CO + H2O –> CO2  + H2

The methanol synthesis variant developed by Lurgi works at pressures of 50 - 100 bar and at temperatures between 220°C and 280°C with a Cu-Zn-Al2O3 catalyst.

(We submit that "a Cu-Zn-Al2O3 catalyst" would be a zeolite-type mineral similar to the zeolite used by ExxonMobil in their own "MTG"(R), Methanol-to-Gasoline, technology.) 

The production of olefin

In the MtSynfuels® process the methanol is then catalytically converted to DME (Dimethylether) like this

2 CH3OH –> DME  + H2O

and then into hydrocarbons e.g. to

DME  –>  2/3 C3H6 + H2O

The zeolitic catalyser used for this step has a high selectivity for olefins. The conversion occurs at temperatures between 300°C and 550°C and at pressures between one and 20 bar.
 
(The processing temperature might seem high. But, the "conversion of syngas to methanol is exothermic", so heat generated by the reaction might be used to help to reduce needs for added energy; and, thus, increase efficiency and reduce costs. Also, note mention of "DME", which, as we have earlier documented, is a versatile liquid fuel and chemical manufacturing feed stock in it's own right.)
 
The oligomerisation of olefin
 
The product mixture from the methanol conversion is then fed to the next reaction level, where short-chain olefins are built up to larger molecules. For example:

4 C3H6  –>  C12H24

This reaction occurs at temperatures between 150°C and 350°C and at pressures between 35 and 85 bar, using a zeolitic catalyser. The oligomerised products in the area of C10+ are separated by distillation from the product mixture and hydrogenated. The resulting flow directly represents the diesel product of the MtSynfuels® process. Apart from that, during the distillation, a low-molecular gasoline product containing paraffin and aromatics is separated. For the two main products diesel and gasoline a total yield of > 90% (relating to carbon) is specified, whereby the ratio of diesel to gasoline can vary over a wide range. LPG (C3/C4) and light ends (C1/C2) are produced as by-products and water is also produced from the methanol conversion process.

Lurgi gives the energy efficiency of the process chain of 67% as an advantage over the FT path (< 63%). The overall efficiency, including all operating materials, is however about the same for both paths. The gasoline product from the MtSynfuels(R) process has a significantly better quality than the gasoline-like by-product of an FT systhesis."

We're glad they improved the efficiency of the process, relative to "the FT path".

But, either way, you get gasoline from syngas; and, you get syngas from ... Coal.