Methanol stoichiometry

An analysis of these equations for an arbitrary set of parameters will be performed in Section 4.8. In the next section, we start with the analysis of the case of equal oxygen and methanol stoichiometries, when the system discussed has an exact solution (Kulikovsky, 2005b). 

DMFC Large methanol stoichiometry and small current... 

To further investigate the effect of jumper formation it is advisable to consider the case of large methanol stoichiometry and small cell current. In the limit of small current we expand the right side of Eq. (4.233) over j and retain only the linear term. This yields... 

The analysis above shows that the jumper is best seen when methanol stoichiometry greatly exceeds oxygen stoichiometry. Cell polarization curves calculated for the three values of A° with an excess of methanol (A A ) are shown in Figure 4.32(a). As discussed above, the jumper manifests itself as a plateau at a small current density. Furthermore, Eq. (4.247) shows that the product A° J must remain constant. Numerical curves in Figure 4.32(a) confirm this result. 

Coproductioa of ammonium sulfate is a disadvantage of the formamide route, and it has largely been supplanted by processes based on the direct hydrolysis of methyl formate. If the methanol is recycled to the carbonylation step the stoichiometry corresponds to the production of formic acid by hydration of carbon monoxide, a reaction which is too thermodynamicaHy unfavorable to be carried out directly on an iadustrial scale. 

Methanol synthesis served as the model for the true mechanism. Stoichiometry, thermodynamics, physical properties, and industrial production rates were all taken from the methanol literature. Only the reaction mechanism and the kinetics of methanol synthesis were discarded. For the mechanism a four step scheme was assumed and from this the... 

Methanol synthesis will be used many times as an example to explain some concepts, largely because the stoichiometry of methanol synthesis is simple. The physical properties of all compounds are well known, details of many competing technologies have been published and methanol is an important industrial chemical. In addition to its relative simplicity, methanol synthesis offers an opportunity to show how to handle reversible reactions, the change in mole numbers, removal of reaction heat, and other engineering problems. 

The reductions in aqueous methanol of a number of alkyl halides by Co(CN)5 have simple second-order kinetics. For methyl and benzyl halides (RX) the stoichiometries are " ... 

We have now found that replacing water in the melt by methanol leads to large increases in pyridine solubility of product from the treatment, even without tetralin addition. In this paper we characterize the effects of temperature, time, hydrogen pressure, reaction stoichiometry, and addition of various inorganic and organic additives. Because oxygen removal Present Address Chevron Research Co., Box 1627, Richmond, CA 94804. 

After combining all these equations, the overall conversion of biomass into hydrocarbon or methanol adopts the stoichiometry of Reactions (6) and (7) ... 

Note that Equations 2.3 and 2.4 give the same value for rate, as the actual rate of change of each compound is corrected for stoichiometry. This becomes clear by considering the reaction shown in Equation 2.5, where two moles of methanol react with one mole of carbon dioxide and half a mole of oxygen to produce one mole each of carbonic acid dimethyl ester and water. 

If the concentration of methanol is monitored with time, it will decrease twice as fast as carbon monoxide and four times as fast as oxygen as shown in Figure 2.8. However, by adjusting the change in concentration with time for the stoichiometry of the reaction, the determined rate of the reaction will be identical, no matter which of the reagents is monitored during the course of the reaction. Thus, the determined rate of reaction is independent of stoichiometry. 

Because the initial oxygen concentration determines the relative abundance of specific abstracting radicals, ethanol oxidation, like methanol oxidation, shows a variation in the relative concentration of intermediate species according to the overall stoichiometry. The ratio of acetaldehyde to ethene increases for lean mixtures. 

---