Methanol, accessible potential

The question of methanol protonation was revisited by Shah et al. (237, 238), who used first-principles calculations to study the adsorption of methanol in chabazite and sodalite. The computational demands of this technique are such that only the most symmetrical zeolite lattices are accessible at present, but this limitation is sure to change in the future. Pseudopotentials were used to model the core electrons, verified by reproduction of the lattice parameter of a-quartz and the gas-phase geometry of methanol. In chabazite, methanol was found to be adsorbed in the 8-ring channel of the structure. The optimized structure corresponds to the ion-paired complex, previously designated as a saddle point on the basis of cluster calculations. No stable minimum was found corresponding to the neutral complex. Shah et al. (237) concluded that any barrier to protonation is more than compensated for by the electrostatic potential within the 8-ring. 

V versus SCE [64], The cathodic limiting reaction is hydrogen evolution, thus forming the acid anion as the coproduct. The apparent electrochemical window of acetic acid is about 4 V [63], whereas that of formic acid is around 1 V [49], For methanol and ethanol, there are reports on limiting cathodic potentials around -2 V versus mercury pool electrode [65], and their accessible electrochemical window is around 2 V. The cathodic limiting reactions are probably hydrogen evolution and an alkoxide formation. 

Rh, Pt, etc. Plans are under way in this laboratory for studies of the static and dynamic structure of CO on binary and ternary alloys (e.g., ruthenium/platinum/tin) in methanol for fuel-cell applications. Such alloys display enhanced resistance to CO poisoning, and the nature of this resistance is appropriate for NMR investigation. For example, Pt-CO bonding information such as Pt-C connectivities, CO orientation and clustering, are accessible by Ti, T2, isotope dilution, and related techniques. In fact, essentially all of the techniques used in the past 20 years to study the solid-gas interface should now be applicable to NMR-electrochemistry, with the added bonus of potential control. 

Among the methods that have the possibility for identification of specific compounds in solvent extracts, GC/MS has been the most studied. However, a disadvantage to the use of nonpolar solvents is that potentially soluble molecules may not be accessible to the solvent and their absence may bias the conclusions drawn. For this purpose, mixed solvents such as benzene/methanol should be... 

This further demonstrates that the micropores formed during the thermal treatment are necessary for oxygen to access the Pt-nanoparticle active sites. Authors also evaluated the durability of the Pt C/MC hybrids through repeated CV cycles with the appropriate lower and upper potential limits in an 02-saturated electrolyte containing 0.5 mol of methanol. The results showed that the variation in the current density was only about 4 % after 40 cycles, which means that the Pt C/MC electrode has a considerable stable electrocatalytic activity for ORR in the presence of methanol [24]. 

Hydroalkoxylation reactions refer to the addition of an alcohol over an insaturation. This highly atom economical process is potentially a straightforward and clean access to ethers, and the reaction is successfully applied at the industrial level for the production of MTBE (methyl terf-butyl ether) and ETBE (ethyl tert-butyl ether) from isobutylene and methanol or ethanol. If this transformation is well known with activated olefins (reaction referred to a Michael addition), a real challenge is the synthesis of ethers from unactivated olefins. Veiy few reactions involving carbohydrates or polyols have been reported to date and most of them involve isobutylene as this substituted olefin is prompt to generate stabilized carbenium ion under acidic conditions. Dimerization reactions of the alcohol or isobutylene are the main side reactions that have to be avoided in order to reach high selectivities into the desired ethers. ... 

In the aftermath of the 1973 oil crisis, independently from market environment, MTO route has always attracted a lot of attention and was poised as a potential way for on-purpose catalytic conversion of non-oil-based feedstocks or intermediates. One could hardly call methanol transformation to olefins a new technology. Since the early 1980s, MTO technology has been considered to be the second best among the emerging solutions. Nobody knows whether the oil had been too accessible or the lack of industrial experience has delayed a sustainable implementation of the process for several decades. 

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