Methanol as fuel

Not mentioned in the table is the direct use of methanol as fuel for automobiles. It is added in small amounts to gasoline, sometimes as a blend with other alcohols such as f-butyl alcohol, to increase octane ratings and lower the price of the gasoline. Experimentation is even being done on vehicles that bum pure methanol. This fuel use is usually captive but a good estimate is that it may account for almost 10% of the methanol produced. 

Direct methanol fuel cell is actually a PEM fuel cell that uses methanol as fuel. Zinc/air fuel cell by definition is not a fuel cell (or at best it is a semifuel cell). Each type of fuel cells has different chemistry, operates at different temperatures and is at a different stage of development. Most of the development and demonstration to date has been with the PEM fuel cells. 

In 2009, worldwide production of methanol was around 40 million metric tons. Although this amount represents only 0.01% of the worldwide gasoline production, it is nearly equivalent to the total biodiesel and bioethanol production [11], From this number, it is clear that a large-scale replacement of gasoline by methanol as fuel would require an enormous increase of worldwide methanol synthesis capacities. Today, chemical intermediates dominate methanol consumption. Formaldehyde a platform molecule for the synthesis of polymer resins - is responsible for nearly half of the total demand. Acetic acid, MTBE, and methyl methacrylate - a monomer -constitute another 25% [7, 12]. Direct fuel and additive usage accounts for 15% of demand but is expected to rise. 

As compared to hydrogen, methanol as fuel offers the ease of storage in regular fuel tanks for transportation. This is to be compared to pressurized (400 bar) hydrogen or its storage as a hydride, from which it has to be released in a controllable manner. As seen below, methanol has to be oxidized in a series of electrochemical reactions giving six electrons, water and carbon dioxide. 

With regard to the following theoretical analysis that had to be carried out in order to allow a sound interpretation of the results, experiments varying only the inlet temperature and the fuel content seemed to be most suitable and easy to perform. As a consequence, an extinction line was recorded. All experiments were performed in a burner with a configuration according to fig. 1 and with methanol as fuel. 

FIGURE 4.24 Schematic illustration of how two different fuel cells work with pure hydrogen as fuel (left), and with methanol as fuel (right). (From Nunes S.P., Review on fuel cells. Presentation at EMS Summer School, NTNU, Trondheim, Norway, 2003. With permission.)... 

Fig. 10 Two different routes for using methanol as fuel for a fuel cell.

Carbon aerogels and xerogels have been used as supports for Pt and Pt-based electrocatalysts for proton-exchange membrane fuel cells (PEMFCs), also known as polymer-electrolyte fuel cells [56,58,83-90], These fuel cells are convenient and environmentally acceptable power sources for portable and stationary devices and electric vehicle applications [91], These PEMFC systems can use H2 or methanol as fuel. This last type of fuel cell is sometimes called a DMFC (direct methanol fuel cell). 

For methanol as fuel, the cell voltage calculated from thermodynamic data is 1.215 V, but here in practice open circuit voltages of about 0.7 V are achieved and... 

As outlined above, biomass feedstock can also be employed for the production of syngas and, thus, methanol produced from biomass-derived syngas and fuels obtained through processing of biomass-based methanol can be considered as typical biofuels. Blends with petrol containing up to 20% of methanol can be used in combustion engines without elaborate modifications. However, the comparatively low energy density and safety concerns have limited so far broad applications of methanol as fuel. Another option is the use... 

Table 11.5 Experimentally reported results for membrane reactors employing methanol as fuel...

Wang et al. [111] presented a thorough study of MEAs for DMFC prepared with different loadings of Vulcan XC-72 as MPL. Polarization and power plots were obtained with 1.5 M methanol as fuel and humid air (50 % RH) as oxidant. The results (Fig. 7.18) show that 1 mg cm of carbon as MPL at the anode or the cathode presents the highest power density when compared to 0.5 and 1.5 mg cm ... 

Similarly to catalyst development, activities dealing with integrated reactors and complete systems for steam reforming in microreactors are dominated by systems applying methanol as fuel, ethanol steam reformers being the exception. 

Figure 6. Voltage-current curve of a DMFC single cell at 60 °C using air as oxidant and methanol as fuel with various concentrations. The points and lines are experimental and calculated results, respectively.

Table 3. Peak stack power, energy efficiency, energy density and open circuit voltages of a 28-cell DMFC stack with 22 cm electrode area operated at 60 "C using air as oxidant and methanol as fuel with different concentrations.

Figiire 14. (A) Comparison of power outputs between DMFC stack and system. (B) Plot of the internally consumed current versus output current. The simulated DMFC system contains a 28-cell stack with 22 cm electrode area at 60 °C using air as oxidant and 1. OM methanol as fuel. 

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