Effect on carbon number

Fig. 18, Support effects on carbon number distribution for cobalt catalysts (473 K, H2/ CO = 2,1, 2000 kPa, 50-60% CO conversion).

Alkene protonation at pore mouths can exclusively lead to secondary carbenium ions. In addition, the alkene standard protonation enthalpies increase with the number of carbon atoms inside the micropore because charge dispersive effects are supposed to be more effective on carbon atoms inside the micropores. 

In rats, inhalation exposure to 330-1,000 ppm during gestation caused maternal weight loss and clear maternal hepatotoxicity, but no effect on conception, number of implants, or number of resorptions (Schwetz et al. 1974). There were no gross anomalies, although fetal size was somewhat decreased. These data suggest that the fetus is not preferentially sensitive to carbon tetrachloride, and effects of carbon tetrachloride on fetal development and post-natal survival are likely secondary to maternal toxicity. 

Carbon formation is also different for diesel and gasoline. The long chain hydrocarbons present in diesel or kerosene fuel are more difficult to reform than the shorter chain hydrocarbons present in gasoline, while aromatics in gasoline hinder the overall reaction rate. An example is found in the results of Ming et who showed that SR of n-Ci required a higher steam/ carbon ratio to avoid coke formation than i-Cg. The cetane number of the feed had little effect on carbon formation. Carbon formation can often be attributed to fuel pyrolysis that takes place when the diesel fuel is vaporized. This is considerably decreased when the steam content in feed increases. 

The same criteria were used for start-of-cycle and deactivation lumping. Start-of-cycle lumping was based on thermodynamics and molecular-reaction similarity. The deactivation kinetic lumps contain the start-of-cycle lumps as a subset. The additional deactivation lumps were required to properly describe the effect of carbon number on aging rate. 

Figure 9. Effect of carbon number range on foam volume (initial stage) ((- -) C10.lt SAE (9EO) (-%-) Clt.H SAE (9EO) (-A-,) C9 + 11PAE (8EO))...

Two studies that used subjects with COHb concentrations of up to 15% reported no changes in the ability to do tasks involving coordination (Stewart et al. 1970 Wright et al. 1973). Stewart et al. (1970) used several tests of manual dexterity. In one, subjects had to pick up small pins, place them in small holes, and then put collars over the pins. No effects attributable to carbon monoxide exposure were found at COHb up to 15%. Wright et al. (1973) also observed no effects on a number of coordination tasks at COHb of 5% and 7%. One study did report a decrement in a hand-eye coordination task (5% COHb) (Putz et al. 1976). 

Table 1 Effect of Carbon Number of Fatty Acid on Yield and Weight Gain of Etherified Wood Meal for Etherification Reaction of Wood Meal (3 g) with PGE (30 g) at 140°C for 3 h in the Presence of Various K Salts of Fatty Acids as Catalyst (2 mol % Based on PGE)...

The diffusion-enhanced olefin readsorption model described in Section III,C was used to predict the effect of carbon number on chain growth probability and paraffin selectivity. The model requires only one adjustable parameter the exponent c in a hydrocarbon diffusivity equation that depends on molecular size ( ), but that is identical for paraffins and olefins of equal size ... 

Fig. 24. Effect of enhanced a-olefin readsorption rates on carbon number distributions (simulations experimental/model parameters as in Fig. 16).

Fig. 27. Effect of diffusion-enhanced a-olefin cracking catalytic function on carbon number distribution (simulations experimental/model parameters as in Fig. 15, 10% CO conversion). (A) FT synthesis without cracking function (B) with intrapellet cracking function, jS = 1.2 (C) with extra pellet cracking function, jS = 1.2. (a) Carbon selectivity vs. carbon number (b) Flory plots.

The latter values are approximately five times larger. This shows that the simple dependence of the hydrophobic effect on the number of carbon atoms becomes rather complicated when considering the interfacial properties. These differences thus may be suggestive of the differences in orientation of the aUcyl chains at the interfaces. This subject has been recently investigated by measuring surface tension and interfacial tension near the freezing point of the oil (alkanes) phase under supercooled measurements, as described further below. 

Any element less electronegative than carbon will have the same effect on oxidation number as hydrogen. Thus, the oxidation numbers of carbon in CHgLi and in CH4 are the same (-4), and the reaction of CH3CI with lithium (to be discussed in Section 14.3) involves reduction of carbon. 

Figure 5.32 Effect of carbon number of alkyl ammonium groups on PaNO>. ( ) Reacted with various tertiary amines (O) reacted with various tertiary amines and then trimethylamine. Transport numbers of nitrate ions relative to chloride ions were measured by electrodialysis using a 1 1 mixed salt solution of sodium nitrate and sodium chloride (concentration of sodium ions 0.04 N) at 1.0 mA cm 2 for 60 min at 25.0 °C under vigorous agitation.

Figure 42 Dependence of the Isotope effect on the number of carbon atoms In the product (reproduced from Reference 140).

Effect of carbon number in hydrocarbon reductant on the selective catalytic reduction of NO over cation-exchanged MFI zeolites... 

FIGURE 8.7. The effect of carbon number on the surface tension of water increases rapidly with the addition of each carbon unit, as illustrated for the series of short-chain alcohols. 

Once a carbon membrane of high performance is produced, the effect of exposure to water vapor must be considered. It has been reported that the selectivity of a typical membrane decreases as the amount of sorbed water increases [38]. Not many studies have taken into accoimt this phenomenon very seriously, although it becomes quite important when a carbon membrane is commercialized. This is primarily due to the fact that water vapor can be foimd in a large number of process stream [38]. To date, only Jones and Koros [39, 40] have studied this phenomenon in detail, and they proposed the use of composite membranes (coated DuPont s Teflon AF1600 and AF2400) as a solution to this drawback. On the other hand, the humidity found in the ambient atmosphere can also have an adverse effect on carbon membrane performance. Therefore, the study of storage conditions for carbon membranes is also an important consideration for carbon membrane research in the future. 

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