Olefin hydrocarbons physical properties

The feedstocks used ia the production of petroleum resias are obtaiaed mainly from the low pressure vapor-phase cracking (steam cracking) and subsequent fractionation of petroleum distillates ranging from light naphthas to gas oil fractions, which typically boil ia the 20—450°C range (16). Obtaiaed from this process are feedstreams composed of atiphatic, aromatic, and cycloatiphatic olefins and diolefins, which are subsequently polymerized to yield resias of various compositioas and physical properties. Typically, feedstocks are divided iato atiphatic, cycloatiphatic, and aromatic streams. Table 2 illustrates the predominant olefinic hydrocarbons obtained from steam cracking processes for petroleum resia synthesis (18). 

Hydrocarbons are segmented into a variety of categories. Each category possesses a distinct molecular profile and, in turn, set of chemical and physical properties. Each class of hydrocarbons therefore has historically served different markets. Crude petroleum is composed of four major hydrocarbon groups paraffins, olefins, naphthenes, and aromatics. 

The contribution of the various classes of hydrocarbons to the formation of particulate organic compounds is a complex function of their relative ambient concentrations, gas-phase reactivity, and ability to form products whose physical properties, especially vapor pressures, are of prime importance in the physical mechanisms controlling the gas-to-aerosol conversion process. In view of the results discussed previously, cyclic olefins appear to be the most important class of organic aerosol precursors. This is due to their high gas-phase reactivity and their ability... 

The four first members of the methane series are gases those containing a greater number of atoms of carbon up to eleven are liquids, and the higher members are solids. The paraffin oil which is burned in lamps consists of a mixture of the liquid members, and paraffin candles largely consist of the solid members. They are all practically insoluble in water. The olefines have similar physical properties, and benzene is a volatile liquid. Iodine, sulphur, and phosphorus dissolve in the liquid hydrocarbons. 

The reactions of atomic sulfur with olefins are in many respects similar to the reactions of atomic oxygen with these substances. There are, however, a number of very significant differences attributable to chemical and physical properties peculiar to the two atomic species. In addition, S-atom reactions with olefins resemble those of CHj with these hydrocarbons. Where therefore appropriate, reference will be made to both oxygen atom and methylene chemistry. 

Roberts and co-workers have examined the use of sc-pentane and sc-hexane for FT synthesis over C0/AI2O3. At the same density (0.3 g/cm ) similar hydrocarbon product distribution was noted for each solvent, but CO conversion in pentane was higher due to the higher pressure required to achieve that density. The enhanced chain-growth probability in SCF-FT synthesis versus gas-phase FT synthesis has been credited to the improved solubility of heavy hydrocarbons and thus the increased availability of vacant sites for a-olefin readsorption and subsequent chain growth, and the elimination of the adsorption layer barrier (85). Further catalyst examination showed that neither catalyst pore radius nor pore volume significantly affected the catalyst activity or selectivity under supercritical conditions (86). These experiments also revealed a deviation in the product distribution from the ASF model which was dependent on the physical properties of the reaction mixture. Elbashir and co-workers have proposed an alternate model for SCF-FT synthesis that better accounts for the enhanced adsorp-tion/desorption phenomena observed in supercritical solvents (87). 

Properties. Propylene is an olefin hydrocarbon that is a gas under ambient conditions bnt is normally stored as a liquid under pressin-e. The physical properties of propylene are given in Table 1. Thermodynamic properties are widely reported in the literature. Vapor-liquid equilibria of mixtures of propylene with other hydrocarbons and hydrogen are accurately represented by correlations for hydrocarbon mixtnres, such as the Chao-Seader correlation. 

While dispersant hydrocarbon backbones are currently dominated by conventional polyisobutylene, many more backbones are on the horizon with the potential to provide improved properties, processing, overall performance per cost, and the ability to optimize properties to respond to specific engine performance characteristics. Some of these (Fig. 8) include high vinylidene PIB, olefin copolymers (OCP) and poly-alpha olefins (PAO). Each of these will be discussed in terms of their structure and reactivity, physical properties and how these translate into strengths and weaknesses in the final application. 

The aniline point (or mixed aniline point) is useful as an aid in the characterization of pure hydrocarbons and in the analysis of hydrocarbon mixtures. Aromatic hydrocarbons exUbit the lowest, and paraffins the highest vdues. Cycloparaffins and olefins exhibit values that lie between fiiose for paraffins and aromatics. In homologous series the aniline points increase with increasing molecular weight Although it occasionally is used in combination with other physical properties in correlative methods for hydrocarbon analysis, the aniline point is most often used to provide an... 

Paraffins are relatively inactive compared to olefins, diolefins, and aromatics. Few chemicals could be obtained from the direct reaction of paraffins with other reagents. However, these compounds are the precursors for olefins through cracking processes. The C -Cg paraffins and cycloparaffms are especially important for the production of aromatics through reforming. This section reviews some of the physical and chemical properties of C1-C4 paraffins. Long-chain paraffins normally present as mixtures with other hydrocarbon types in different petroleum fractions are discussed later in this chapter. 

The physical and chemical properties of the X -phosphorins 118 and 120 are comparable to those of phosphonium ylids which are resonance-stabilized by such electron-pulling groups as carbonyl or nitrile substituents Thus they can be viewed as cyclic resonance-stabilized phosphonium ylids 118 b, c, d). As expected, they do not react with carbonyl compounds giving the Wittig olefin products. However, they do react with dilute aqueous acids to form the protonated salts. Similarly, they are attacked at the C-2 or C-4 positions by alkyl-, acyl- or diazo-nium-ions Heating with water results in hydrolytic P—C cleavage, phosphine oxide and the hydrocarbon being formed. 

Readsorption enhancements caused by slow removal of a-olefins from catalyst pellets and interpellet voids are described by Eqs. (8)-(14). In these equations, transport rates are described in terms of the physical structure of the support and of the reactive and diffusive properties of reactant and products in molten hydrocarbons. Chain growth and termination rate constants are assumed to be independent of chain size and of surface structure and chemical properties. The readsorption probability (jSr) is also assumed... 

Sinfelt has greatly contributed to the catalyses of bimetallic nanoparticles [18]. His group has thoroughly studied inorganic oxide-supported bimetallic nanoparticles for catalyses and analyzed their microstructures by an EXAFS technique [19-22]. Nuzzo and co-workers have also studied the structural characterization of carbon-supported Pt/Ru bimetallic nanoparticles by using physical techniques, such as EXAFS, XANES, STEM, and EDX [23-25]. These supported bimetallic nanoparticles have already been used as effective catalysts for the hydrogenation of olefins and carbon-skeleton rearrangement of hydrocarbons. The alloy structure can be carefully examined to understand their catalytic properties. Catalysis of supported nanoparticles has been studied for many years and is practically important but is not considered further here. 

Hydrocarbons — Organic chemical compounds composed only of the elements carbon and hydrogen. Hydrocarbons are the principal constituents of crude oils, natural gas, and refined petroleum products and include four major classes of compounds (alkanes, alkenes, naphthenes, and aromatics) each with characteristic structural arrangements of hydrogen and carbon atoms, as well as different physical and chemical properties. (See also Alkanes, Alkenes, Aromatics, Naphthenes, Olefins, Paraffin, Saturate group.)... 

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