Propane + isobutane

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. 

Evaporative emissions from vehicle fuel systems have been found to be a complex mixture of aliphatic, olefinic, and aromatic hydrocarbons [20,24,33]. However, the fuel vapor has been shown to consist primarily of five light paraffins with normal boiling points below 50 °C propane, isobutane, n-butane, isopentane, and n-pentane [33]. These five hydrocarbons represent the more volatile components of gasoline, and they constitute from 70 to 80 per cent mass of the total fuel vapor [24,33]. 

Investigation of Ethane, Propane, Isobutane, Neopentane, Cyclopropane, Cyclopentane, Cyclohexane, Allene, Ethylene, Isobutene, Tetramethylethylene, Mesitylene, and Hexamethylbenzene. Revised Values of Covalent Radii (by Linus Pauling and L. O. Brockway)... 

Fig. 2.—Theoretical intensity curves for ethane, propane, isobutane and neopentane. The arrows show the positions of the maxima and minima measured on the photographs.

Several of the lower molecular weight aliphatic compounds, in a mixture, are part of the roasted coffee aroma. A nine-compound mixture with roasted coffee aroma contained isopentane, n-hexane, acetaldehyde, dimethyl sulfide, propanal, isobutanal, isopentanal, methanol, and 2-methylfuran.20 In addition, the freshness of aroma and taste has been correlated with 2-methylpropanal and diacetyl. When the concentration of these falls off, so does the taste.21 Other aliphatic compounds that are steadily lost from ground roasted coffee, unless it is vacuum packaged, include methyl formate, methyl acetate, methyl thioacetate, and acetone.22 The concentrations in roast coffee for four compounds whose contribution to the fresh flavor have long been known are dimethyl sulfide (4 ppm), methyl formate (12 ppm), isobutanal (20 ppm), and diacetyl (40 ppm). The taste thresholds are 0.1, 0.5, 0.5, and 1.0 ppm, respectively, in the brew made with 5 g coffee per 100 ml water.15... 

Hydrocarbons have also been considered as potential propellants for pharmaceutical aerosols. To date concerns regarding flammability seem to have precluded significant developments with propane, isobutane, butane, and mixtures of these alkanes [28]. 

A, Find the optimum liquid concentration of the propane isobutane mixture in an auto lefrigerated alkylation reactor. The exothermic heat (10 Btu/h) of the alkylation reaction is removed by vaporization of the liquid in the reactor. The vapor is com pressed, condensed, and flashed back into the reactor through a pressure letdown valve. The reactor must operate at 50°F, and the compressed vapors must be condensed at 110°F. 

These reactions have a zero order vs. the alkane. The gas phase at the end of the reaction includes a 1 1, 2 1 and 3 1 methane ethane mixture for propane, isobutane and neopentane, respectively. 

The liquid solubilities of propane, isobutane, and normal butane in hydrogen fluoride and the liquid solubilities of hydrogen fluoride in these three hydrocarbons in the temperature range 0 to 50°C. are given by the following equations. 

Oxyfunctionalization of lower paraffins such as methane, ethane, propane, and butanes has recently attracted much attention (5, 330, 331, 347-350). Oxidation of -butane to maleic anhydride is an industrial example (346, 351). The oxidation of propane and isobutane with heteropoly catalysts was first reported in 1979 (352). Ai (324a) and Centi et al. (324b, 324c) reported that heteropoly compounds catalyze the oxidation of lower paraffins, especially propane, isobutane, and pentane (324). 

Hydrate Propane + isobutane Reference Kamath and Holder (1984)... 

Hydrate Propane + isobutane Reference Paranjpe et al. (1987) Phases L y—H—V—Lhc... 

Paranjpe, S.G., Patil, S.L., Kamath, V.A., Godbole, S.P., HydrateFormation in Crude Oils and Phase Behavior of Hydrates in Mixtures of Methane, Propane, Isobutane, and n-Butane, paper presented at the Third Chemical Congress of North America, Toronto, June 5-10 (1988). 

Typical alkylation reactions are those of propane, isobutane, and n-butane by the ferf-butyl or sw-butyl ion. These systems are somewhat interconvertible by competing hydride transfer and rearrangement of the carbenium ions. The reactions were carried out using alkyl carbenium ion hexafluoroantimonate salts prepared from the corresponding halides and antimony pentafluoride in sulfuryl chloride fluoride solution and treating them in the same solvent with alkanes. The reagents were mixed at —78°C warmed up to — 20°C and quenched with ice water before analysis. The intermolecular hydride transfer between tertiary and secondary carbenium ions and alkanes is generally much faster than the alkylation reaction. Consequently, the alkylation products are also those derived from the new alkanes and carbenium ions formed in the hydride transfer reaction. 

At first the calculations were performed on eleven simple molecules ethane, propane, isobutane, neopenthane, ethene, 2-butene, methanol, dimethyl ether, dimethoxymethane, trimethoxymethane, and tetramethoxymethane. The correlation between calculated and experimental principal values is shown in Figure 1. The correlation coefficient is R2 = 0.97 and the root mean square deviation of the calculated from the experimental values is 13 ppm. 

In a natural gasoline fractionation system there are usually six chemical species present in appreciable quantities methane, ethane, propane, isobutane, n-butane, and n-pentane. A mixture of these species is placed in a closed vessel from which all air has been removed. If the temperature and pressure are fixed so that both liquid and vapor phases exist at equilibrium, how many additional phase-rule variables must be chosen to fix the compositions of both phases ... 

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