Search

..................................

Select Level of Detail

At a Glance

General

Technical

............................

+ Bioproducts from Syngas - Methanol

............................

Access BioWeb Content

Search

Explore By Topic

Browse Index

............................

BioWeb Glossary

Search

Alphabetical Listing

............................

Contributors Log in

bioweb.sungrant.org » Technical » Bioproducts » Bioproducts from Syngas » Methanol

Products from Syngas—Methanol (Catalyst)	Printer Friendly

In its simplest form, syngas (also called producer gas, town gas, blue water gas, and synthesis gas among others) is composed of carbon monoxide (CO) and hydrogen (H2), which provide the building blocks to produce a number of organic compounds. During the 1800’s, coal gasification was used for lighting and heating. The production of fuels and chemicals from syngas began in the early 20th century. Today, methanol and ammonia are produced from syngas, and in addition to hydrogen, constitute its major uses.    In principle, syngas can be produced from any hydrocarbon feedstock, including natural gas, naphtha, residual oil, petroleum coke, coal, and biomass. Using numerous synthesis pathways, a large number of organic compounds can be produced from syngas (figure 1).               As a transportation fuel, methanol (CH3OH) can be used directly or blended with other petroleum derived fuels. Methanol is an important chemical intermediate and is used to produce, among others, methyl tert-butyl ether (MTBE), formaldehyde, dimethyl ether (DME), acetic acid, olefins, methyl amines, and methyl halides. Today, methanol is produced almost exclusively (90%) from syngas derived from the steam reforming of natural gas (Davenport, 2002). However, a variety of other feedstocks could be used, including biomass resources.   Methanol synthesis reactions. Methanol synthesis began in the 1800’s with the isolation of “wood” alcohol from the dry distillation (pyrolysis) of wood. At the beginning of the 20th century, research to convert syngas to liquid fuels and chemicals led to the concurrent discovery of a methanol and the Fischer-Tropsch synthesis processes. Methanol is a byproduct of Fischer-Tropsch synthesis when alkali metal promoted catalysts are used. Methanol synthesis is now a well-developed commercial catalytic process with high activity and very high selectivity (>99%). It can be produced from syngas via steam reforming (no oxygen used), autothermal reforming (oxygen used), or a combination of the two. The syngas produced from reforming natural gas is fed to a reactor containing a catalyst which produces methanol and water vapor. The crude methanol contains up to 18% water, ethanol, higher alcohols, ketones, and ethers. Purification is by distillation in one unit which removes volatile compounds and a second unit which removes the water and higher alcohols. Unreacted syngas is recirculated back to the methanol reactor resulting in an overall conversion efficiency of greater than 99%. A generic methanol synthesis process flow diagram is shown in figure 2.

Methanol synthesis catalysts
Catalysts play a pivotal role in syngas conversion reactions. The basic concept of a catalytic reaction is that reactants adsorb onto the catalyst surface, rearrange, and combine into products that then desorb from the catalyst surface. One of the fundamental functional differences between syngas synthesis catalysts is whether or not the adsorbed CO molecule dissociates on the catalyst surface (i.e., sticks to the catalyst surface and falls apart into a C atom and an O atom which react with H2 to make a hydrocarbon chain link (CH2) and water. For higher alcohol synthesis, CO dissociation is a necessary reaction condition. For methanol synthesis, the CO bond remains intact (to maintain the oxygen atom in the methanol).   The first high temperature, high-pressure methanol synthesis catalysts were ZnO/Cr2O3 operated at 350°C and 250-350 bar (101325 pascals = 1 atmosphere = 1.01325 bar = 14.7 pounds per square inch) and containing 20 to 75 Zn (atom%). They demonstrated high activity and selectivity for methanol synthesis and resistant to sulfur poisoning inherent in syngas produced from coal gasification. As the ability to remove syngas impurities (e.g., sulfur, chlorine, and metals) improved, interest in easily poisoned catalysts such as Cu intensified. The last high temperature methanol synthesis plant closed in the mid-1980’s (Fiedler, 2003) and presently, low temperature and pressure processes based on Cu catalysts are used for all commercial production of methanol from syngas.   In 1966, ICI introduced a new, more active Cu/ZnO/Al2O3 catalyst capable of producing methanol at low temperatures (220-275°C) and pressure (50-100 bar). The most active Cu methanol catalysts have high Cu content (optimum of about 60% Cu) with the maximum quantity limited by the need for sufficient refractory oxide to prevent Cu sintering (i.e., the partial melting of small metal particles in or on catalysts which subsequently coagulate to form larger particles). Cu crystallites (define?) are the active sites in the catalysts, although the chemical state of the active site (i.e., whether it is an oxide, a metal, etc.) has not been determined. The ZnO in the catalyst formulation  creates a high Cu metal surface area, is suitably refractory at methanol synthesis temperatures, and hinders the agglomeration of Cu particles. ZnO also interacts with Al2O3 to form a spinel (i.e., a type of mineral formation) that provides a robust catalyst support. Acidic materials like alumina are known to catalyze methanol dehydration reactions to produce dimethyl ether (DME)--interaction of the ZnO with the Al2O3 support material improves methanol selectivity by reducing the potential for DME formation.   Additional catalyst formulations have been proposed with the intent of increasing methanol yields (Klier, 1982). The addition of heavier alkali metals (such as cesium, Cs) to Cu/ZnO mixtures improves methanol yields but lighter alkali metals (such as potassium, K) tend to increase production of higher alcohols. Copper-thorium oxide (Cu/ThO2) intermetallic catalysts have demonstrated high methanol formation from CO2-free syngas, but deactivate rapidly in the presence of CO2 (Klier, 1982). Copper-zirconium (Cu/Zr) catalysts produce methanol synthesis in CO-free syngas at 5 atm and 160-300°C (Herman, 1991).  Supported palladium (Pd) catalysts have also demonstrated methanol synthesis activity in CO2-free syngas at 5 -110 atm between 260-350°C.   Catalysts are typically prepared by precipitating metal salts such as nitrates or sulfates. Methanol synthesis catalysts are commercially produced by a number of manufacturers (table 1). Commercial methanol synthesis catalysts have lifetimes of 3-5 years under normal operating conditions.          Impurities in the syngas can cause poisoning and sintering of methanol synthesis catalysts. Copper catalysts are extremely sensitive to site-blocking poisons such as reduced sulfur. Gas-phase sulfur concentrations need to be kept below 1 part per million (ppm) and preferably below 0.1 ppm. The addition of ZnO to the Cu catalyst formulation limits sulfur poisoning by diverting the sulfur away from the active Cu sites and scavenging it from the gas stream to form ZnS and ZnSO4. Commercial Cu-ZnO catalysts can absorb 0.4 wt% sulfur and still maintain 70% of their activity (Kung, 1992). Sulfur contamination is generally not a problem in the commercial production of methanol because the syngas used is produced from steam reforming of methane using nickel (Ni) catalysts. Ni catalysts are very intolerant of sulfur and sulfur compounds are generally removed from the feedstock (to below 0.1 ppm) prior to gasification.   Contamination with metals that display Fischer-Tropsch activity (e.g., metal carbonyl compounds particularly those of iron (Fe) and Ni) must be avoided. Trace amounts of metal carbonyl compounds can be present in syngas feed streams, especially if stainless steel tubing is used. Volatile metal carbonyl compounds deposit on the catalyst surface, block the active sites, and affect selectivity. Ni increases the production of CH4 and Fe increases the production of Fischer-Tropsch products. Metal carbonyl concentrations should be below 5 parts per billion (ppb) (Wender, 1996).   Alkali metals should also be avoided because they reduce overall catalyst activity and increase the production of higher alcohols.  Unwanted SiO2 in the catalyst promotes wax formation and unreacted (non-spinel) alumina enhances DME formation. Other poisons to be avoided are arsenic (As) and phosphorus (P).   The presence of chlorine (Cl) in syngas has been correlated with the sintering of copper crystallites most likely due to the formation of volatile copper chloride compounds. Adsorbed Cl atoms block or modify active Cu catalyst sites by forming CuCl2 which has a low melting point and high surface mobility that accelerates catalysts sintering. The presence of trace amounts of chlorine also causes enhanced sulfur poisoning probably due to the formation of Zn chlorides which diminishes the ability of Zn to capture sulfur. HCL content in the syngas needs to be less than 1 ppb to avoid poisoning (Twigg, 2001). Under commercial conditions, the process used to generate the syngas usually removes the chlorine.   The Cu/ZnO catalysts have no activity for COS (carbonyl sulfide) adsorption or dissociation (in the range of 0.6-9 ppm) and at typical methanol synthesis conditions, COS does not react with H2 to form H2S (Kung, 1992). However, COS, which can be a catalyst poison, is more problematic in the liquid phase methanol synthesis process where the syngas is bubbled through a liquid containing suspended catalysts. Table 2 summarizes the syngas purity requirements for methanol production.

Methanol Synthesis Reactors
A major challenge associated with methanol synthesis is removing the large excess heat produced during reaction. Methanol synthesis catalytic activity increases at higher temperatures but so does the potential for competing side reactions which produce CH4, DME, methyl formate, higher alcohols and acetone (Supp, 1984). Catalyst lifetimes are also reduced by continuous high temperature operation and typically process temperatures are maintained below 300°C to minimize catalyst sintering.   Overcoming thermodynamic constraints (i.e., limitations to chemical reactions such as temperature and pressure) is another challenge. The maximum conversion efficiency of syngas to methanol in a single pass through the catalyst reactor is limited to about 25% (Wender, 1996). Higher conversion efficiencies per pass can be realized at lower temperatures where the methanol equilibrium is shifted towards products; however, catalyst activities generally decrease as the temperature is lowered. Removing the methanol as it is produced is another strategy used for overcoming the equilibrium limitations and improving the per pass conversion process efficiencies. Methanol is either physically removed (condensed out or physisorbed onto a solid) or converted to another product like dimethyl ether, methyl formate, or acetic acid. This approach is predicated on the fact that after a certain point, adding more syngas (higher flow rate) to the reactor doesn’t increase methanol production. Removal of the methanol already produced (either by condensation or reacting it to make another product) is needed to permit production of more methanol.   These two constraints are the main features considered when designing a methanol synthesis reactor (also called a methanol converter). Numerous methanol converter designs have been commercialized and can be roughly categorized into two types-adiabatic or isothermal reactors. Adiabatic reactors often contain multiple catalyst beds separated by gas cooling devices and involve either direct heat exchange or injection of cooled, fresh or recycled syngas. Axial temperature profiles (i.e., up and down the reactor along its long dimension) often have a sawtooth pattern that is low at the point of heat removal and increases linearly between the heat exchange sections of the reactor. Isothermal reactors are designed to continuously remove heat and operate like a heat exchanger with an isothermal axial temperature profile (i.e., temperature doesn’t change along the reactor length).   The ICI Low pressure Quench Converter (Pinto, 1977; Rogerson 1971; Rogerson 1984) is the most widely used adiabatic methanol converter. It is operated at 50-100 bar and 270°C. The Cu/ZnO/Al2O3 catalyst is contained in a single bed supported by an inert material. Adding cold fresh and recycled syngas quenches the synthesis reaction and controls the reaction temperature. The gas is injected at appropriate depths within the reactor through spargers (i.e., gas jets that spray the gas into the reactor similar to an aerator in a fish tank) called lozenges. The lozenges are oriented in horizontal layers that cross the converter from side to side. Each lozenge has an outer surface covered with wire mesh and a central pipe that delivers the cold gas. An improved version of this reactor (called an ARC converter) is available and differs from the original by having a catalyst bed separated by distribution plates to form multiple consecutive catalyst domains rather than a single continuous catalyst bed.   Other adiabatic converters include the Kellogg, Brown, and Root (now Halliburton) reactor which have multiple fixed bed reactors arranged in series and separated by heat exchangers. The reactors have a spherical geometry to reduce construction costs and use less catalyst compared to the ICI Quench Converter. All of the recycled syngas is fed directly into the first reactor stage. The Haldor-Topsoe Collect, Mix, Distribute (CMD) adiabatic converter operates on a similar principle. Vertical support beams separate the catalyst beds. The gas inlet at the bottom of the reactor provides fresh syngas that flows radially upwards through the first catalyst bed. At the top of the reactor, this first pass-through gas is evenly mixed with quench gas (i.e., an inert gas, usually nitrogen, added to the reactor to cool it down) so that it flows radially downwards through the second catalyst bed (Dybkjaer, 1981). The cited benefit of this design is an increase in per pass conversion yields. Toyo Engineering Corporation has designed a multistage radial flow methanol converter (MRF-Z™) that uses bayonet boiler tubes (i.e., pointed tubes through which gas circulates and heat is removed by contact with the outer walls) for intermediate cooling. The tubes divide the catalyst into concentric beds.   One of the more widely used commercial isothermal methanol converters is the Lurgi Methanol Converter (Haid, 2001; Supp 1984). This reactor operates at pressures of 50-100 bar and temperatures between 230-265°C and uses a proprietary Lurgi methanol catalyst (Cu/ZnO/Cr2O3 + promoters). The reactor consists of a shell and tube design surrounded by boiling water to remove heat (i.e., boiling water is at a lower temperature than the reaction and thus can serve as a mechanism to remove heat). Varying the pressure of the boiling water controls the reactor temperature. Byproduct steam is produced at 40-50 bar and can be used to run the compressor or to provide heat for the distillation process used to purify the methanol. Conversion rates per pass of 4-7vol% have been reported with production of close to 1 kg of methanol per liter of catalyst per hour (Wender, 1996).   Other isothermal methanol converters include the Tube Cooled Converter, a simple to operate reactor in which the syngas enters at the bottom and is distributed by a manifold through tubes which act as heat exchangers prior to the gas entering the catalyst bed. The Linde isothermal reactor (the Variobar converter) uses coiled helical tubes embedded in the catalyst bed for heat removal. Spacers separate the multi-layer coils and boiling water is circulated through the tubes. Mitsubishi Gas Chemical in collaboration with Mitsubishi Heavy Industry has developed the MGC/MHI Superconverter (Takase, 1985) which uses double-walled tubes filled with catalyst in the annular space (i.e., the void space around the outside of the round tubes) between the inner and outer tubes. The syngas enters the inner tubes and is heated as it progresses through the tube.  The gas then passes downward through the catalyst bed in the annular space. Heat is removed on both sides of the catalyst bed by the boiling water surrounding the tubes as well as by the feed gas introduced into the inner tube (Tijm, 2001). A high conversion rate (~14 % methanol in the reactor outlet) is reported for this reactor (Fiedler, 2003).   Additional methanol converter designs include technologies using three phase systems similar in principle to the slurry reactors used for Fischer Tropsch synthesis. These technologies are collectively known as Liquid Phase Methanol Synthesis (LPMEOH™). The LPMEOH™ process uses a supported Cu/ZnO catalyst (20-45 wt%) dispersed in circulating mineral oil and operates at temperatures of 225-265°C and pressure of 50 bar. The three phase slurry reactor provides improved temperature control by uniformly dissipating the heat of reaction into the high heat capacity liquid. Liquid phase methanol synthesis (LPMeOH) was invented in late 1970’s (Hamelinck, 2001) and first tested by Air Products and Chemicals, Inc., in an 8 tpd pilot plant in the 1980’s (Bhatt, 1999). Later, in a joint venture between Eastman Chemical Company and Air Products and Chemicals, Inc., a 260 TDP LPMeOH demonstration plant was built in Kingsport, TN and began operation in 1997 (Bhatt, 1999; Wender, 1996). ChemSystems, Inc. and Air Products and Chemicals, Inc. with U.S. Department of Energy funding developed a liquid-entrained (i.e., a liquid phase, slurry reactor in which the catalyst is suspended in the liquid) catalytic reactor to convert low H2/(CO + CO2) ratio syngas into methanol (Bhatt, 1999; DOE, 1992). The ability to convert low stoichiometric ratio (CO rich) syngas enhances the potential to produce methanol from coal or biomass. (i.e., to make syngas conversion processes as productive as possible, the optimum CO/H2 ratio is needed. Different feedstocks produce different ratios, but the ratio can be altered via the water-gas shift reaction). Brookhaven National Laboratory developed a liquid phase methanol synthesis process that can be operated at low pressures (<5 atm) with up to 90% conversion without syngas recycling (Tijm, 2001). This work has been done in collaboration with Amoco and in 1998 a 50 milliliter mini-pilot plant was successfully operated.   Two other methanol conversion processes are based on systems where the methanol is continuously removed from the gas phase by selective adsorption on a solid or in a liquid. The Gas-Solid-Solid Trickle Flow Reactor (GSSTFR) utilizes an adsorbent such as SiO2/Al2O3 to trap the methanol (Herman, 1991; Pass, 1990). The solid adsorbent is collected in holding tanks and the methanol is desorbed. In the Reactor System with Interstage Product Removal (RSIPR), a liquid solvent is used to adsorb the methanol (Herman, 1991).   The operating parameters of several commercial methanol synthesis reactors are summarized in table 3.

Commercial Production of Methanol from Syngas
As of January 2002, global annual methanol production capacity was 12.8 billion gallons (38 million tonnes, 9 million GJ) (Davenport, 2002). Methanex is the largest producer with SABIC second (17 and 6.5% of global capacity respectively). About 20% of 2001 world production occured in North America (Davenport, 2002). U.S. consumption in 2001 was 28% of the world supply (Davenport, 2002). There are 18 methanol production plants in the U.S. (Lidderdale, 2001). Recently, Lurgi won a contract to build a methanol plant in Iran with a proposed capacity of 1.8 million tonnes/yr, making it the world’s largest plant. Operation was expected to begin in 2004. [http://www.qipc.net/news/june/jun0051.htm].   For production of methanol from natural gas, most of the capital cost is for reforming and conditioning the gas. For the ICI process, the allocation of capital costs are 2% for desulfurization, 32% for reforming/gas cooling, 14% for steam production, 24% for compression, 22% for methanol synthesis, and 6% for distillation (Wender, 1996). Using a slurry reactor instead of a tubular reactor reduces capital costs and decreases the compression cost by reducing the pressure drop across the reactor. LPMEOH investment costs are expected to be 5-23% less than gas phase reactors of the same capacity (Hamelinck, 2001).   A number of studies have estimated the cost of producing methanol from biomass or coal syngas rather than from natural gas. These studies are summarized in tables 4 and 5. Production of methanol from biomass could increase the cost by $0.30/gallon to $0.55/gallon compared with natural gas depending on study assumptions (Vermillion, 2001).

References
Bhatt, B. L., Heydorn, E. C., Tihm, P. J. A., Street, B. T., and Kornosky, R. M. (1999). "Liquid phase methanol (LPMEOH) process development." Preprints - American Chemical Society, Division of Petroleum Chemistry, 44(1), 25-27. Chemical Market Reporter. (2003). "Price Quote of Methanol, Formaldehyde, and Acetic Acid." Bailey, E. (1979). "The coal to methanol alternative." Coal Technol. (Houston), 2nd(3), 149-61. ChemSystems. (1990). "Optimization of Electricity-Methanol Coproduction. Configurations of Integrated-Gasification-Combined-Cycle/Once-Through." EPRI/GS-6869. Chinchen, G. C., Mansfield, K., and Spencer, M. S. (1990). "The Methanol Synthesis - How Does It Work." Chemtech, 20(11), 692-699. Davenport, B. (2002). "Methanol." Chemical Economics Handbook Marketing Research Report, SRI International, Menlo Park, CA.  Report number 674.5000. Davenport, B., Gubler, R., and Yoneyama, M. (2002). "Gasoline Octane Improvers." Chemical Economics Handbook Marketing Research Report, SRI International, Menlo Park, CA. Report number 543.7500. DOE, U. S. (1992). "Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOHTM) Process." DOE/FE-0243P, U.S. Department of Energy. Dybkjaer, I. (1981). "Topsoe methanol technology." CEER, Chem. Econ. Eng. Rev., 13(6), 17-25. Dybkjaer, I., and Christensen, T. S. (2001). "Syngas for large scale conversion of natural gas to liquid fuels." Studies in Surface Science and Catalysis, 136(Natural Gas Conversion VI), 435-440. Fiedler, E., Grossmann, G., Kersebohm, D. B., Weiss, G., and Witte, C. (2003). "Methanol." Ullmann's Encyclopedia of Industrial Chemistry Release 2003, 6th Edition, Wiley-VCH Verlag GmbH & Co.KGaA. Haid, J., and Koss, U. (2001). "Lurgi's Mega-Methanol technology opens the door for a new era in down-stream applications." Studies in Surface Science and Catalysis, 136(Natural Gas Conversion VI), 399-404. Hamelinck, C. N., and Faaij, A. P. C. (2001). "Future prospects for production of methanol and hydrogen from biomas." NWS-E-2001-49; ISBN 90-73958-84-9, Utrecht University. Herman, R. G. (1991). "Chapter 7 - Classical and Non-Classical Route for Alcohol Synthesis." New Trends in CO Activation, L. Guczi, ed., Elsevier, Amsterdam, 281-285. Klier, K. (1982). "Methanol Synthesis." Advances in Catalysis, 31, 243-313. Kung, H. H. (1992). "Deactivation of Methanol Synthesis Catalysts - a Review." Catalysis Today, 11(4), 443-453. Ladebeck, J. (1993). "Improve methanol synthesis." Hydrocarbon Processing, International Edition, 72(3), 89-91. Larson, E. D. a. K., R.E. (1992). "Production of Methanol and Hydrogen from Biomass." Report No. 271, Princeton University, Center for Energy and Environmental Studies, Princeton, NJ. Lee, S. (1990). Methanol Synthesis Technology, CRC Press, Boca Raton, Fla. Lidderdale, T. C. M. (2001). "MTBE Production Economics." Energy Information Agency. Maiden, C. J. (1983). "New Zealand gas to gasoline plant." Apea J., 23(1), 33-43. Michaels, H. J. (1979). "Methanol from coal using the Koppers-Totzek process." Coal Technol. (Houston), 2nd(3), 163-78. Mudge, L. K., Robertus, R. J., Mitchell, D. H., Sealock, L. J., Jr., and Weber, S. L. (1981). "Economics of methanol and SNG production from biomass via catalytic gasification." Energy Biomass Wastes, 5th, 687-722. Novem. (2000). "Technical and Economic Databases - Biomass Energy Conversion Systems for the Production of Gaseous and/or Liquid Energy Carriers." Report No. GAVE-9915. Pass, G., Holzhauser, C., Akgerman, A., and Anthony, R. G. (1990). "Methanol synthesis in a trickle-bed reactor." AIChE Journal, 36(7), 1054-60. Pinto, A., and Rogerson, P. L. (1977). "Optimizing the ICI low-pressure methanol process." Chem. Eng. (N. Y.), 84(14), 102-8. Rogerson, P. L. (1971). "The ICI [Imperial Chemical Industries] low pressure methanol process." Ingenieursblad, 40(21), 657-63. Rogerson, P. L. (1984). "Chapter 2-2: The ICI Low-Pressure Methanol Process." Handbook of Synfuels Technology, R. A. Meyers, ed., McGraw-Hill Book Company, New Tork. Rostrup-Nielsen, J. R. (2000). "New aspects of syngas production and use." Catalysis Today, 63(2-4), 159-164. Salmon, R. (1986). "Economics of Methanol Production from Coal and Natural Gas." ORNL-6091, Oak Ridge National Laboratory.  P.L. Spath and D.C. Dayton, Preliminary screening—technical and economic assessment of synthesis gas to fuels and chemicals with emphasis on the potential for biomas-derived syngas, National Renewable Energy Laboratory, NREL/TP-510-34929, December, 2003 Supp, E., and Quinkler, R. F. (1984). "The Lurgi Low-Pressure Methanol Process." Handbook of synfuels technology., R. A. Meyers, ed., McGraw-Hill, 113 - 131. Synthetic Fuels Associates, Inc. (1983). "Coal Gasification Systems: A Guide to Status, Application, and Economics." EPRI/AP-3109. Takase, I., and Niwa, K. (1985). "Mitsubishi (MGC/MHI) methanol process." CEER, Chemical Economy & Engineering Review, 17(5), 24-30. Tijm, P. J. A., Waller, F. J., and Brown, D. M. (2001). "Methanol technology developments for the new millennium." Applied Catalysis A, 221, 275-282. Twigg, M. V., and Spencer, M. S. (2001). "Deactivation of supported copper metal catalysts for hydrogenation reactions." Applied Catalysis, A: General, 212(1-2), 161-174. U.S. Department of Energy. (1990). "Assessment of Costs and Benefits of Flexible and Alternative Fuel Use in the U.S. Transportation Sector. Technical Report 5: Costs of Methanol Production from Biomass." Vermillion, B., Nguyen, P., and Tsan, E. Q. (2001). "Feasibility Study of Methanol as Transportation Fuel." University of California, San Diego - Methanol Conversion Group, San Diego, CA. Wender, I. (1996). "Reactions of synthesis gas." Fuel Processing Technology, 48(3), 189-297. Wham, R. M., and Forrester III, R. C. "Available Technology for Indirect Conversion of Coal to Methanol and Gasoline: A Technology and Economics Assessment." Alternative energy sources III, Miami Beach, FL, 3-18. Wyman, C. E., Hinman, N. D., Bain, R. L., and Stevens, D. J. (1993). "Chapter 21 - Ethanol and Methanol from Cellulosic Materials." Renewable energy : sources for fuels and electricity, T. B. Johansson and L. Burnham, eds., Island Press, Washington, D.C., 865-923.