Hydrogen-carbon ratios estimates

The reactor was tested using a range of methanol and water concentrations, and researchers found the best results using a water and methanol mixture with a steam-to-carbon ratio (S C) of 1.1 1. They were able to achieve 90% conversion at 260 °C with a reactant liquid flow rate of 12 cmYh. Assuming a fuel cell efficiency of 60% and 80% hydrogen utilization, they estimated the output power to be 15 W. Eventually the complete system will include a cata-... 

Conversion data listed in Table 2 indicate that in the hydrogenation of 4-amino-ethyl benzoate using cyclohexane as a solvent the AI2O3 supported Ru and Rh catalysts are more active than the carbon supported ones. In addition, the conversion of aromatic ester is smaller on Pd/C catalyst than on the carbon supported Ru and Rh. In ethyl acetate the hydrogenation proceeded slower than in cyclohexane, and Rh being more active than Ru. The trans/cis isomer ratio estimated from TLC results varied between 1/3 and 1/1. The UV active by-products were formed in coupling reactions. 

There is related evidence from the studies by Rust (13) on the oxidations of neat 2,3- and 2,4-dimethylpentanes that the strain energy in the five-membered ring is higher than 6.3 kcal. Rust found mainly diperoxy compound from the oxidation of the 2,4-isomer, showing that the internal hydrogen atom abstraction from the y-carbon atom competes favorably (/— 19-fold faster) with external abstraction of a similar hydrogen atom. With estimated A-factors of 1010-8 sec."1 and 108 3 liter/mole-sec., respectively for the internal and external abstractions and an effective liquid phase concentration of tertiary C—H bonds of lOAf, we predict a ratio... 

Figure 7 The Vostok ice-core record (Petit et aL, 1999). (a)-(c) Carbon dioxide, methane, and oxygen isotope ratios (expressed as 5 0) of oxygen in air extracted from the ice. (d) Hydrogen isotope ratios (expressed as or 5D) in the ice. This record is a proxy for local temperature, (e) Sodium in the ice, a measure of sea salt aerosol deposition, (f) Dust in the ice, a measure of continental aerosol deposition, (a)-(c) are plotted against the estimated age of the iee air (d)-(f) are plotted against the estimated age of the ice.

Figure 3.37 shows the spectrum of the hydrocarbon octane. Note that the integral can be used to estimate the total number of hydrogens (the ratio of CH3 to CH2-type carbons) since all of the CH2 hydrogens are in one group and the CH3 hydrogens are in the other. 

Today, petroleum is our primary hydrocarbon feedstock. It is estimated [1] that at the beginning of 2004, worldwide reserves were 1.27 trihion barrels of oil. At current usage this supply is projected to last -50 years. The other important hydrocarbon feedstocks are coal and natural gas. Methane, CH4, is the major component of natural gas (75-90%) and as shown in Fig. 7.2, is one of the most abundant hydrocarbons on the planet and is widely distributed. Current estimates are that natural gas reserves (6,100 trillion cubic feet) are comparable to oil on an energy content basis. If the estimates of natural gas in methane hydrate deposits in the deep oceans are considered, the amount of methane on the planet could far exceed the known oil reserves Given the abundance, wide distribution, hi er hydrogen to carbon ratio and low sulfur content compared to oil and coal, methane could become the hydrocarbon feedstock of choice that could lead to a Methane Economy" for the next several decades. 

In one patent (31), a filtered, heated mixture of air, methane, and ammonia ia a volume ratio of 5 1 1 was passed over a 90% platinum—10% rhodium gauze catalyst at 200 kPa (2 atm). The unreacted ammonia was absorbed from the off-gas ia a phosphate solution that was subsequently stripped and refined to 90% ammonia—10% water and recycled to the converter. The yield of hydrogen cyanide from ammonia was about 80%. On the basis of these data, the converter off-gas mol % composition can be estimated nitrogen, 49.9% water, 21.7% hydrogen, 13.5% hydrogen cyanide, 8.1% carbon monoxide, 3.7% carbon dioxide, 0.2% methane, 0.6% and ammonia, 2.3%. 

The introduction of isotopes into a compound alters the coupling pattern and the chemical shifts of the observed spectrum. As shovm in Eigure 1.18, deuterium-induced chemical shift variations have allo ved the estimation of the ratio of isomers 90a-d formed in Eq. (2) vhen R = Ph, R = CHjCOOH, and DCOOD/ Et3N is used for the hydrogen transfer [136]. The three sp -carbons Cl, C2 and C3 each afford a distinct singlet for the four possible isotopomers 90a-d (replacement of by shifts the resonances of the adjacent carbon nuclei to lo ver frequency) [137]. 

This difficulty for CS 776 can be assessed quantitatively. Le Bertre (1990) derives a mass loss rate from IRC-20131 of 4.5 x 10 7 MQ a-1. Scaled to the outflow velocity of the material of 26 km s-1 (Zuckerman Dyck 1989) instead of the assumed value of 15 km s 1 and using Le Bertre s distance of 1.3 kpc instead of their estimate of 1.43 kpc, the re-computed mass loss rate from Claussen et al. (1987) is 6.6 x 10 Mq a-1 in reasonable agreement with the rate estimated by Le Bertre (1990). Because the separation of the A star companion from the carbon star CS 776 is 1.81", the projected separation between the two stars is 3.6 x 1016 cm. Therefore, according to equation (3), the column density of circumstellar hydrogen between us and the A star companion to CS 776 is 1.5 x 1019 cm-2. However, the total extinction toward this companion is Av = 1.71 mag (Le Bertre 1990) which, for a standard interstellar dust to gas ratio, corresponds to a hydrogen column density of 3x 1021 cm-2 (Spitzer 1978). This column density is consistent with the expected concentration of interstellar matter within the plane of the Milky Way. Thus, towards the companion to CS 776, there appears to be about 100 times more interstellar than circumstellar matter. Therefore, unless the diffuse bands are extremely strong in the circumstellar matter around CS 776, it seems quite likely that the bulk of the diffuse bands in the spectrum result from interstellar matter. 

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