Hydrocarbons molecular weight

Fischer-Tropsch reaction The catalytic reaction of hydrogen and carbon monoxide (synthesis gas ) to produce high-molecular weight hydrocarbons. 

My faculty colleagues of the Institute also bring great expertise in the areas of anionic, cationic, and radical polymerization to the transformation of low-molecular-weight hydrocarbons into macromole-... 

Almost any hydrocarbon can serve as a starting material for production of ethylene and propene Cracking of petroleum (Section 2 16) gives ethylene and propene by processes involving cleavage of carbon-carbon bonds of higher molecular weight hydrocarbons... 

Cracking (Section 2 16) A key step in petroleum refining in which high molecular weight hydrocarbons are converted to lower molecular weight ones by thermal or catalytic carbon-carbon bond cleavage... 

Polyethylene. Polymerization of ethylene results in an essentially straight-chain high-molecular-weight hydrocarbon. 

Other high molecular weight hydrocarbon polymers are not biodegradable, but oligomers of <7j -l,4-isoprene (83), butadiene (84), and styrene (85), are degradable. And there has been further confirmation of biodegradation of oligomeric ethylene (86). 

Uses. Aluminum chloride is used as a catalyst in a wide variety of manufacturing processes, such as the polymerization of light molecular weight hydrocarbons in the manufacture of hydrocarbon resins. Friedel-Crafts reactions (qv) which employ this catalyst are used extensively in the synthesis of agricultural chemicals, pharmaceuticals (qv), detergents, and dyes (12). 

Asphalt [8052-42-4] is defined by the American Society for Testing and Materials (ASTM) (1) as a dark brown to black cementitious material in which the predominating constituents are bitumens that occur in nature or are obtained in petroleum processing. Bitumen is a generic term defined by ASTM as a class of black or dark-colored (soHd, semisoHd, or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, of which asphalts, tars, pitches, and asphaltites are typical. 

Relatively high steam requirements to desorb high-molecular-weight hydrocarbons... 

Aluminium chloride Resin manufacture by polymerization of low molecular-weight hydrocarbons Friedel-Crafts reactions to manufacture detergent alkylate, agrochemicals, drugs Irritation due to formation of HCI with moisture... 

Physical solvent processes have a high affinity for heavy hydrocarbons. If the namral gas stream is rich in C3+ hydrocarbons, then the use of a physical solvent process may result in a significant loss of the heavier molecular weight hydrocarbons. These hydrocarbons are lost because they a c released from the solvent with the acid gases and cannot be economically recovered. 

The distribution of the products obtained from this reaction depends upon the reaction temperature (Figure 5.1-4) and differs from those of other poly(ethene) recycling reactions in that aromatics and alkenes are not formed in significant concentrations. Another significant difference is that this ionic liquid reaction occurs at temperatures as low as 90 °C, whereas conventional catalytic reactions require much higher temperatures, typically 300-1000 °C [100]. A patent filed for the Secretary of State for Defence (UK) has reported a similar cracking reaction for lower molecular weight hydrocarbons in chloroaluminate(III) ionic liquids [101]. An... 

Coke A solid residue from cracking operations, mostly carbon but with a small amount of high-molecular-weight hydrocarbons... 

Higher molecular weight hydrocarbons present in natural gases are important fuels as well as chemical feedstocks and are normally recovered as natural gas liquids. For example, ethane may be separated for use as a feedstock for steam cracking for the production of ethylene. Propane and butane are recovered from natural gas and sold as liquefied petroleum gas (LPG). Before natural gas is used it must be processed or treated to remove the impurities and to recover the heavier hydrocarbons (heavier than methane). The 1998 U.S. gas consumption was approximately 22.5 trillion ft. ... 

For more aromatics yield, the end point of the feed may be raised to include higher molecular weight hydrocarbons in favor of hydrocracking and dehydrocyclization. However, excessive hydrocracking is not desirable because it lowers liquid yields. 

The minor products are generally 1-3% of the total yield and arose from (a) side-chain fragmentation producing hydrogen and low-molecular-weight hydrocarbons (b) addition of these fragments to the free olefin (c) dimerization and trimerization of the free olefin (d) fragmentation of the alkyl radical and cation intermediates. 

The desorption using a nonadsorbing medium such as nitrogen equals a pressure swing process because the purge gas reduces the partial pressure of the n-alkane and works as a vacuum. This variant also is only suitable for the isolation of n-alkanes from low molecular weight hydrocarbon mixtures like gasoline fractions. 

Note Like sulfuric acid (q.v.) ort/io-phosphoric add is a universal reagent, with which almost all classes of substance can be detected at high temperatures (150-180 °C) by charring e.g. high molecular weight hydrocarbons (mineral oils) [20]. The colors and fluorescences produced at lower temperatures (<120°C) and their intensities are very dependent on the temperature and period of heating. It is not possible to use meta- or pyrophosphoric acid in place of or/Ao-phosphoric add, since, for instance, amanita toxins react well with alcoholic phosphoric add only weakly with aqueous phosphoric add and not at all with meta- or pyrophosphoric acid [17]. 

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