Methanol transport

Usually, methanol concentrations of 2 M or less are used in DMFCs, due to the serious problem of crossover of methanol through the electrolyte membranes. When this occurs, the transported methanol reacts directly on the cathode and seriously reduces the DMFC voltage. As a result of catalyst poisoning and mixed potential loss at the cathode the energy density using low concentration, methanol fuel cannot match that of current batteries. The anode reaction is ... 

Pervaporation of methanol and methyl rerf-butyl ether (MTBE) using hollow fibers coated with polypyrrole, poly(A/-methylpyrrole), and polyaniline was studied by Martin et al. [77]. A microporous hollow-fiber ultrafiltration membrane made of cellulose was coated with a conjugated polymer. An uncoated hollow fiber had only a slight preference for transporting methanol ( tnethanoi/MTBE = 1.06), attributed to the more polar methanol being more soluble in the somewhat polar cellulose-based film. The polypyrrole-coated fiber had only... 

About half of the wodd production comes from methanol carbonylation and about one-third from acetaldehyde oxidation. Another tenth of the wodd capacity can be attributed to butane—naphtha Hquid-phase oxidation. Appreciable quantities of acetic acid are recovered from reactions involving peracetic acid. Precise statistics on acetic acid production are compHcated by recycling of acid from cellulose acetate and poly(vinyl alcohol) production. Acetic acid that is by-product from peracetic acid [79-21-0] is normally designated as virgin acid, yet acid from hydrolysis of cellulose acetate or poly(vinyl acetate) is designated recycle acid. Indeterrninate quantities of acetic acid are coproduced with acetic anhydride from coal-based carbon monoxide and unknown amounts are bartered or exchanged between corporations as a device to lessen transport costs. 

Coa.1 Reserves. As indicated in Table 2, coal is more abundant than oil and gas worldwide. Moreover, the U.S. has more coal than other nations U.S. reserves amount to about 270 biUion metric tons, equivalent to about 11 x 10 MJ (1 x 10 ° BTU = 6600 quads), a large number compared to the total transportation energy use of about 3.5 x lO " MJ (21 quads) per year (11). Methanol produced from U.S. coal would obviously provide better energy security benefits than methanol produced from imported natural gas. At present however, the costs of producing methanol from coal are far higher than the costs of producing methanol from natural gas. 

Sypher-MueUer International, Inc., Euture Transportation Euels MlcoholEuels, Energy, Mines and Resources—Canada, Project Mile Report, A Report on the Use of Methanol in Large Engines in Canada, May 1990. 

Office of Pohcy, Planning, and Analysis, Assessment of Costs and Benefits ofElexible and Alternative Euel Use in the U.S. Transportation Sector, Technical Report 3 (Methanol Production and Transportation Costs) Pub. DOE/P/E—0093, U.S. Department of Energy, Washington, D.C., Nov. 

U. Hilger, G. Jain, E. Scheid, and P. Pischinger, "Development of a Direct Injected Neat Methanol Engine for Passenger Car AppHcations," SAP Paper 901521, SAE Euture Transportation Technology Conf. and Expo. (San Diego, Calif., Aug. 13—16,1990). 

T. B. BlaisdeU, M. D. Jackson, and K. D. Smith, "Potential of Light-Duty Methanol Vehicles," SAE Paper 891667, SAE Euture Transportation Technology Conf. andExpo. (Vancouver, Canada, Aug. 7—10,1989), Society of Automotive Engineers, Warrendale, Pa. 

M. A. DeLuchi, "Emissions of Greenhouse Gases from the Use of Gasoline, Methanol, and Other Alternative Transportation Puels," ia W. Kohl, ed.. Methanol as an yiltemativeFuel Choice yin yissessment, ]oim. Hopkias Poreiga PoHcy lastitute, Washiagtoa, D.C., 1990, pp. 167—199. 

A viable electrocatalyst operating with minimal polarization for the direct electrochemical oxidation of methanol at low temperature would strongly enhance the competitive position of fuel ceU systems for transportation appHcations. Fuel ceUs that directiy oxidize CH OH would eliminate the need for an external reformer in fuel ceU systems resulting in a less complex, more lightweight system occupying less volume and having lower cost. Improvement in the performance of PFFCs for transportation appHcations, which operate close to ambient temperatures and utilize steam-reformed CH OH, would be a more CO-tolerant anode electrocatalyst. Such an electrocatalyst would reduce the need to pretreat the steam-reformed CH OH to lower the CO content in the anode fuel gas. Platinum—mthenium alloys show encouraging performance for the direct oxidation of methanol. 

The nameplate capacity of worldwide methanol plants is given by country in Table 2 (27). A significant portion of this capacity is based on natural gas feedstock. Percent utilization is expected to remain in the low 90s through the mid-1990s. A principal portion of this added capacity is expected to continue to come from offshore sources where natural gas, often associated with cmde oil production, is valued inexpensively. This has resulted in the emergence of a substantial international trade in methanol. In these cases, the cost of transportation is a relatively larger portion of the total cost of production than it is for domestic plants. 

The advent of a large international trade in methanol as a chemical feedstock has prompted additional purchase specifications, depending on the end user. Chlorides, which would be potential contaminants from seawater during ocean transport, are common downstream catalyst poisons likely to be excluded. Limitations on iron and sulfur can similarly be expected. Some users are sensitive to specific by-products for a variety of reasons. Eor example, alkaline compounds neutralize MTBE catalysts, and ethanol causes objectionable propionic acid formation in the carbonylation of methanol to acetic acid. Very high purity methanol is available from reagent vendors for small-scale electronic and pharmaceutical appHcations. 

Poly(ethylene oxide) associates in solution with certain electrolytes (48—52). For example, high molecular weight species of poly(ethylene oxide) readily dissolve in methanol that contains 0.5 wt % KI, although the resin does not remain in methanol solution at room temperature. This salting-in effect has been attributed to ion binding, which prevents coagulation in the nonsolvent. Complexes with electrolytes, in particular lithium salts, have received widespread attention on account of the potential for using these materials in a polymeric battery. The performance of soHd electrolytes based on poly(ethylene oxide) in terms of ion transport and conductivity has been discussed (53—58). The use of complexes of poly(ethylene oxide) in analytical chemistry has also been reviewed (59). 

Biofuels. Biofuels are Hquid fuels, primarily used ia transportation (qv), produced from biomass feedstocks. Identified Hquid fuels and blending components iaclude ethanol (qv), methanol (qv), and the ethers ethyl /-butyl ether (ETBE) and methyl /-butyl ether (MTBE), as well as synthetic gasoline, diesel, and jet fuels. 

Whereas near-term appHcation of coal gasification is expected to be in the production of electricity through combined cycle power generation systems, longer term appHcations show considerable potential for producing chemicals from coal using syngas chemistry (45). Products could include ammonia, methanol, synthetic natural gas, and conventional transportation fuels. 

Mobil Oil Corporation has developed a process on a pilot scale that can successfully convert methanol into 96 octane gasoline. Although methanol can be used directiy as a transportation fuel, conversion to gasoline would eliminate the need to modify engines and would also eliminate some of the problems encountered using gasoline—methanol blends (see Alcohol fuels Gasoline and other motor fuels). 

Under the National Energy PoHcy Act of 1992 nonpetroleum-based transportation fuels are to be introduced in the United States. Such fuels include natural gas (see Gas, natural), Hquefied petroleum gas (qv) (LPG), methanol (qv), ethanol (qv), and hydrogen (qv), although hydrogen fuels are not expected to be a factor until after the year 2000 (see also Alcohol fuels Hydrogen energy). 

C2. Calculation of Operating conditions and Transport Criteria for the UCKRON Test Problem as a Methanol Synthesis Experiment in the Rotoberty ... 

In the United States, in particular, recent legislation has mandated sweeping improvements to urban air quality by limiting mobile source emissions and by promoting cleaner fuels. The new laws require commercial and government fleets to purchase a substantial number of vehicles powered by an alternative fuel, such as natural gas, propane, electricity, methanol or ethanol. However, natural gas is usually preferred because of its lower cost and lower emissions compared with the other available alternative gas or liquid fuels. Even when compared with electricity, it has been shown that the full fuel cycle emissions, including those from production, conversion, and transportation of the fuel, are lower for an NGV [2]. Natural gas vehicles offer other advantages as well. Where natural gas is abundantly available as a domestic resource, increased use... 

When relatively small amounts of hydrogen are required, perhaps in remote locations such as weather stations, then small transportable generators can be used which can produce I-I7m h. During production a 1 1 molar mixture of methanol and water is vaporized and passed over a base-metal chromite" type catalyst at 4(X)°C where it is cracked into hydrogen and carbon monoxide subsequently steam reacts with the carbon monoxide to produce the dioxide and more hydrogen ... 

In the case of systems containing ionic liquids, components and chemical species have to be differentiated. The methanol/[BMIM][PF6] system, for example, consists of two components (methanol and [BMIM][PFg]) but - on the assumption that [BMIM][PFg] is completely dissociated - three chemical species (methanol, [BMIM] and [PFg] ). If [BMIM][PFg] is not completely dissociated, one has a fourth species, the undissociated [BMIM][PFg]. From this it follows that the diffusive transport can be described with three and four flux equations, respectively. The fluxes of [BMIM] ... 

Moore, R. M. Gottesfeld, S. and Zelenay, P. (1999). A Comparison Between Direct-Methanol and Direct Hydrogen Fuel Cell Vehicles. SAE Future Transportation Technologies Conference. Paper 99FTT-48 (August). 

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