Isobutane data

Figure 10. Comparison of experimetnal kinetic energy release distributions to phase-space calculations for (a) dehydrogenation of n-butane by Co+ and (b) loss of methane in reaction of Co+ with isobutane. Data from reference 38.

Isobutane Data not available Data not available Not pertinent Data not available... 

As discussed in Sec. 4, the icomplex function of temperature, pressure, and equilibrium vapor- and hquid-phase compositions. However, for mixtures of compounds of similar molecular structure and size, the K value depends mainly on temperature and pressure. For example, several major graphical ilight-hydrocarbon systems. The easiest to use are the DePriester charts [Chem. Eng. Prog. Symp. Ser 7, 49, 1 (1953)], which cover 12 hydrocarbons (methane, ethylene, ethane, propylene, propane, isobutane, isobutylene, /i-butane, isopentane, /1-pentane, /i-hexane, and /i-heptane). These charts are a simplification of the Kellogg charts [Liquid-Vapor Equilibiia in Mixtures of Light Hydrocarbons, MWK Equilibnum Con.stants, Polyco Data, (1950)] and include additional experimental data. The Kellogg charts, and hence the DePriester charts, are based primarily on the Benedict-Webb-Rubin equation of state [Chem. Eng. Prog., 47,419 (1951) 47, 449 (1951)], which can represent both the liquid and the vapor phases and can predict K values quite accurately when the equation constants are available for the components in question. 

Figure 4 3. Vapor-solid equilibrium constants for isobutane. (From Gas Processors Suppliers Associotion, Engineering Data Book, 10th Edition.)...

Table 14.9 Vapor-Liquid Equilibrium Data for the Methanol (l)-Isobutane...

Leu and Robinson (1992) reported data for this binary system. The data were obtained at temperatures of 0.0, 50.0, 100.0, 125.0, 133.0 and 150.0 °C. At each temperature the vapor and liquid phase mole fractions of isobutane were measured at different pressures. The data at 133.0 and 150.0 are given in Tables 14.9 and 14.10 respectively. The reader should test if the Peng-Robinson and the Trebble-Bishnoi equations of state are capable of describing the observed phase behaviour. First, each isothermal data set should be examined separately. 

Fig. 12.4. Vapor-to-water transfer data for saturated hydrocarbons as a function of accessible surface area, from [131]. Standard states are 1M ideal gas and solution phases. Linear alkanes (small dots) are labeled by the number of carbons. Cyclic compounds (large dots) are a = cyclooctane, b = cycloheptane, c = cyclopentane, d = cyclohexane, e = methylcyclopentane, f = methylcyclohexane, g = cA-l,2-dimethylcyclohexane. Branched compounds (circles) are h = isobutane, i = neopentane, j = isopentane, k = neohexane, 1 = isohexane, m = 3-methylpentane, n = 2,4-dimethylpentane, o = isooctane, p = 2,2,5-tri-metbylhexane. Adapted with permission from [74], Copyright 1994, American Chemical Society...

None of the experimental techniques described by Bonner, however, has been capable of providing reliable vapor-liquid equilibrium data at the combined extremes of elevated temperature and reduced pressure, conditions applicable to most commercial polymer-stripping operations. This problem has been addressed by Meyer and Blanks (1982), who developed a modified isopiestic technique that could be used when solubilities are low. Although the success of this new technique was demonstrated using just polyethylene with isobutane and propane, the idea shows considerable promise for obtaining data at unusual conditions of temperature and pressure. 

POM composed of (NH4)3PMoi204o data were collected at a reaction temperature of 380°C, with an isobutane-rich feedstock (26 mol % isobutane, 13% oxygen, 12% steam, remainder helium), and a residence time of 3.6 s. At the very beginning of its lifetime, the fresh POM was completely unselective and inactive. After approximately 100 hours reaction time, it was 6.5% converted, with a selectivity to methacrylic acid of 42% and to methacrolein of 13%. The main by-product was carbon dioxide. Therefore, the equilibration time was necessary for the generation of the active and selective sites. 

Blais, C. and Hayduk, W. Solubility of butane and isobutane in butanol, chlorobenzene, and carbon tetrachloride. /. Chem. Eng. Data, 28(2) 181-183, 1983. 

Parks, G.S., Shomate, C.H., Kennedy, W.D., and Crawford, B.L., Jr. The entropies of n-butane and isobutane, with some heat capacity data for isobutane, J. Chem. Phys., 5(5) 359-363, 1937. 

Proton and C-nmr, ESCA, and Raman studies provide a wealth of information which unfortunately is not subject to a unique interpretation. The main conclusion to be drawn therefore is that the structure of the solvent stabilized cation is still unproven. Gas phase estimates of the heat of formation of the norbomyl cation imply a rather marked stability of the stmcture relative to other secondary ions (Kaplan et al., 1970). When combined with other estimates of the heat of formation of the t-butyl cation, however, these data suggest that hydride transfer from isobutane to the norbomyl ion will be endothermic by 6 to 15 kcal mole . This is contrary to experience in the liquid phase behaviour of the ion, and the author s conclusion that their observation of enhanced stability is evidence of stabilization by bridging deserves further scmtiny. 

This reagent was obtained either from Aldrich Chemical Company, Inc., or Lithium Corporation of America, Bessemer City, NC. A technical data sheet is available from the suppliers. Solutions of ca. 2 M were titrimetrically analyzed for active alkyllithium by the tosylhydrazone method. It is advisable to make certain that the organolithium reagent to be used was prepared in pentane solution. This evaluation can be easily accomplished by the gas chromatographic analysis of the organic layer obtained from the hydrolysis, under a nitrogen atmosphere, of the tert-butyllithium solution to be used. Isobutane and pentane should comprise essentially all of the... 

Our own liquid-phase studies were carried out at 50°-100°C., where the products are stable (16, 17). We obtained more information on radical interactions and determined the effects of dilution with CC14. Our oxidations were carried out by heating known amounts of isobutane, initiator, and oxygen (sometimes with solvents) in sealed glass tubes as described above. Nearly all conversions of isobutane were kept below 1%. Experimental data are summarized in Table I. 

Traylor and Russell (30) have shown recently that similar reactions for the cumyloxy radical are important in cumene oxidation at 60 °C., and Hendry (12) has provided some quantitative data. At low concentrations of hydrocarbon, Reaction 9 is favored over Reaction 7 (propagation by tert-BuO ), and significant numbers of methyl radicals are formed and converted to Me02 radicals. Chain termination thus shifts from the slow termination by 2 tert-Bu02 (Reaction 6) to Reaction 10, which has a rate constant several hundredfold larger (21). The apparent order of the oxidation in isobutane is then 3/2 a similar relation applies to gas-phase oxidations and is discussed there. 

The very small isobutane yields can not be attributed to the participation of Reaction 3 since the known rate constant data are inconsistent with this. Isobutane must come from some other reactions, as yet undefined. 

Tsang and Hampson Chemical Kinetic Data Base for Combustion Chemistry. Part 1. Methane and Related Compounds [407] Part 2. Methanol [402] Part 3. Propane [403] Part 4. Isobutane [404]... 

It is significant that the mixture yielded propane as the major product (Table III). As noted in our earlier paper on catalytic cracking (6), the predominance of C3 fragments in the cracked products and the absence of isobutane appeared to be a unique property of erionite. Our present data indicate that this is also true for hydrocracking over a dual function erionite. The only exception was that when n-pentane alone was hydro-cracked, equimolal quantities of ethane and propane were found. This shift in product distribution in the presence of n-hexane, a second crackable component, indicated that the reaction path within the intracrystalline space was complicated. 

Yield (wt%) is defined by 100 X [the weight of products divided by the weight of I-butene charged]. 224-TMP = 2,2,4-trimethylpentane, 23-DMH = 2,3-dimethylhexane, etc. Figures in parentheses are research octane number (RON). Hydrocarbons containing 5-7 carbon atoms. JOctenes. Hydrocarbons constaining 9-12 carbon atoms. Catalyst, 1.0 g I-butene, 0.94 g isobutane, 9.4 g. All data were collected at 7 h. 

In general, the data accuracy was surprisingly good. For example, while Deaton and Frost (1946, p. 13) specified that their pure ethane contained 2.1% propane and 0.8% methane, effects of those impurities may have counterbalanced each other those impurities were insufficient to cause the data to fall outside the line formed by other ethane data sets. On the other hand, the simple hydrate data of Hammerschmidt (1934) for propane and isobutane all appear to be outliers on such semilogarithmic plots, because they are at temperatures much too far above the upper quadruple (Q2) point. Obvious outlying data were excluded from this work less obvious outliers may be determined by inspection of the plots and subsequent numerical comparisons. The data, followed by the semilogarithmic plots... 

The phase equilibria data for binary guest mixtures are listed under the lighter component. For example, under the heading of binary guest mixtures of methane will be found data for methane + ethane, methane + propane, methane + isobutane, methane + n-butane, methane + nitrogen, methane + carbon dioxide, and methane + hydrogen sulfide. Concentrations are in mole percent or mole fraction in the gas phase, unless otherwise indicated. 

Isobutane + sodium chloride data sources O 0.0 wt% NaCI Rouher and Barduhn (1969) O 1.1 wt% NaCI Schneider and Farrar (1968) A 9.93 wt% NaCI Schneider and Farrar (1968) X 3.05 wt% NaCI Rouher (1968)... 

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