Alkanes industrial source

An alkene mixture of industrial source (equal amounts of C9-C13 alkenes and alkanes) was used in the alkylation of benzene on three Nafion-silica catalysts with 5%, 13%, and 20% loadings.195 20% Nafion-silica showed high and stable activity and its performance exceeded that of a Y-zeolite-based material. The selectivity to 2-phenylalkanes (25%) was higher than in the Detal process using fluorinated silica-alumina but decreased somewhat with increasing Nafion content. 

Other alkanes also react with steam to give mixtures of CO and H2.) Steam reforming is the principal industrial source of hydrogen gas. Additional hydrogen can be produced by recycling the CO to react further with steam in the water gas shift reaction ... 

Elimination reactions One way to change an alkane into a chemically reactive substance is to form a second covalent bond between two carbon atoms, producing an alkene. The main industrial source of alkenes is the cracking of petroleum. The process of cracking, shown in Figure 23-17, breaks large alkanes into smaller alkanes, alkenes, and aromatic compounds. Why do you suppose the term cracking was applied to this process ... 

A substantial portion of fhe gas and vapors emitted to the atmosphere in appreciable quantity from anthropogenic sources tends to be relatively simple in chemical structure carbon dioxide, carbon monoxide, sulfur dioxide, and nitric oxide from combustion processes hydrogen sulfide, ammonia, hydrogen chloride, and hydrogen fluoride from industrial processes. The solvents and gasoline fractions that evaporate are alkanes, alkenes, and aromatics with relatively simple structures. In addition, more complex... 

Several methodologies can be used to identify not only crude or refined product type, but also the brand, grade, and, in some instances, the source crude. The petroleum industry has yielded conventional methods for the characterization of refined products. The simplest is the routine determination of API gravity and development of distillation curves where NAPL is present. More sophisticated methods include gas chromatography and statistical comparisons of the distribution of paraffinic or n-alkane compounds between certain C-ranges. With increased degradation and decomposition, the straight-chain hydrocarbons ( -alkanes) become less... 

The CH-activation of alkanes and especially of methane and their catalytic conversion to alcohols is one of the major challenges for chemists. Methane as the major part of natural gas is currently the cheapest source of hydrocarbons and the need for methanol will increase in the near future. Methane conversion to methanol would make a conveniently transportable fuel and also a new carbon source for the chemical industry. 

Propane s greatest use is not as a fuel but in the petrochemical industry as a feedstock. As an alkane, it undergoes typical alkane reactions of combustion, halogenation, pyrolysis, and oxidation. Pyrolysis or cracking of propane at several hundred degrees Celsius and elevated pressure in combination with metal catalysts result in dehydrogenation. Dehydrogenation is a primary source of ethylene and propylene ... 

Geochemists and the oil industry routinely screen rock samples for bio-markers that indicate the age and source of hydrocarbon constituents. The conventional extraction takes 48 hours and requires extract clean-up by thin-layer chromatography to separate the alkanes from aromatic hydrocarbons and heteroatom containing species (16). Here the selectivity of SFE in extracting only the alkanes from a mature source rock... 

Alkanes, which are the principal components of natural gas and crude oil, are still the preferred energy source of our society. In regard to the prime importance of alkanes as feedstock for the chemical industry, it appears a waste of resources simply to burn these precious raw materials. Unfortunately, attempts to transform alkanes into more valuable products are hampered by their low reactivity, as best illustrated by the use of alkanes as inert solvents. For example, the cracking process requires temperatures of about 1000 °C in order to convert long-chain alkanes into short-chain alkanes. Controlled conversion of hydrocarbons is difficult to achieve and limited to partial oxidations, such as the conversion of butane into acetic acid. It is obvious that processes that would enable efficient functionalization to occur at low temperature would have enormous potential application. Achievements towards this goal will almost certainly rely on the use of catalysts, which will have to activate the stable C-H bond (375-440 kf mol-1) in order to induce its scission. 

Reaction of a four-carbon unit with sulfur sources such as hydrogen sulfide, carbon disulfide, and elemental sulfur is one of the traditional thiophene syntheses that belong to this category (Equation 18). A wide variety of hydrocarbons, for example, alkanes, alkenes, dienes, alkynes, and diynes, serve as four-carbon units. Another practical method is the sulfuration of 1,4-dicarbonyl compounds (Paal synthesis). The method has become very popular with development of sulfuration reagents such as Lawesson s reagent. The reaction of a,/3-unsaturated nitriles with elemental sulfur in basic media, Gewald synthesis, is also useful for the preparation of 2-aminothiophenes which are important compounds in dyestuff and pharmaceutical industries. 

Aliphatic hydrocarbons include straight chain and branched structures. Industrial solvents, petroleum hydrocarbons, and the linear alkyl benzene sulfonates (LAS) are the primary sources of aliphatic hydrocarbon pollutants. Many microorganisms utilize aliphatic hydrocarbons as carbon sources. Long-chain -alkanes are utilized more slowly due to the low bioavailability that results from their extremely low solubility in water. In contrast, short-chain rc-alkanes show a higher aqueous solubility. 

The zeolites have been first used as catalyst in the 1960s for alkane cracking reactions in petroleum industry.They replaced favorably previously employed alumina based catalysts because of their better therm and mechanical stability. Moreover, they showed higher selectivity. The selectivity finds its source in the zeolite micropore structure with different... 

Hydrocarbons are very minor components of oils and fats but are of dietary and legislative interest. They include alkanes, alkenes such as squalene and carotenes, and polycyclicaromatic hydrocarbons. Squalene (C30H50) is a highly unsaturated open-chain triterpene. It is used in the cosmetic industry after hydrogenation to squalane (C30H62). The most abundant source of squalene is the liver oil of the deep-sea dogfish (Squalus acanthus—hence the name squalene) and some other marine species. Vegetable sources of potential interest include olive oil and amar-anthus (Section 6). 

The principal source of alkanes is petroleum, together witl tl accompanying natural gas. Decay and millions of years of geologicarstresses have transformed the complicated organic compounds that once made up living plants or animals into a mixture of alkanes ranging in size from one carbon to 30 or 40 carbons. Formed along with the alkanes, and particularly abundant in California petroleum, are cycloalkanes (Chap. 9), known to the petroleum industry as naphthenes. 

The basic sources of petrochemical synthesis are benzene and its homologues. The production of these compounds from petroleum is profitable. In 1996, the world requirements for benzene will grow up to 24-26 million tons per year. Non-oxidizing dehydrogenation of alkanes is a subject of intensive investigation. So, the selection and increase of the assortment of highly effective catalysts for the synthesis of olefins and aromatic hydrocarbons from alkanes are very important for development of this branch of industry. There are three main catalysts for non-oxidized dehydrogenation ... 

V-alkanes (No. 1) and n-carboxylic acids (No. 9) occur in all natural materials and are as well used for numerous industrial syntheses (see Table 2). Thus, their appearance in Lippe river water can be attributed to various sources. This is also the case for vanillin (see section Perfumes, odors and additives for cosmetics ). In contrast, di-zvo-propyldisulfide (No. 45) and dipropyltrisulfide (No. 46) which were detected in several water samples (see Table 1) are clearly related to natural sources. It is known that they are formed by blue-green algae (Microcystis flos-aquae) in fresh waters (Hofbauer and Juttner, 1988) and the industrial application is unknown. 

Many of the organic contaminants which were found in Lippe river water were also present in the source samples (see Table 3). The sewage effluent sample and the Seseke river showed the best accordance with the compound spectrum of the Lippe river. However, also in the two tributaries from the rural upper reaches of the river, numerous specific contaminants like 9-methylacridine (No. 8), alkyl phosphates (Nos. 31, 32) and chlorinated alkyl phosphates (Nos. 34, 36) appeared. In the effluent of a pharmaceutical plant, only a few Lippe river contaminants like n-alkanes (No. 1), naphthalene (No. 3), TXIB (No. 21) and caffeine (No. 67) were detected (see Table 3). Therein, mainly structural relatives of androstanone like 3p-hydroxy-5p-androstan-17-one, 3a-hydroxy-5p-androstan-17-one and androstan-50-3,17-dione were present. These compounds are probably by-products of the synthesis of hormone preparations. Some polycyclic aromatic compounds, halogenated compounds and terpenoids were not detected in the source samples (see the underlined compounds in Table 3) and probably have another origin. Representative sampling of various input sources have to be carried out to prove the origin of these compounds. Hexachlorobutadiene (No. 38) and bis(chloropropyl)ethers (No. 44) appear exclusively at the lower reaches of the Lippe river (see Table 1), downstream the chemical plants in Marl. They are attributed to inputs of the chlorochemical industry (see section 3.1). Hence, this suggests their input by an industrial point source. 

Natural gas consists of about 15% methane. The remaining 25% is composed of small alkanes such as ethane, propane, and butane. In the 1950s, natural gas replaced coal as the main energy source for domestic and industrial heating in many parts of the United States. 

Hydrocarbons (particularly aromates and polycyclic hydrocarbons, but also n-alkanes, isoalkanes, cycloalkanes as well as unsaturated hydrocarbons), which enter the atmosphere in the course of petroleum and natural gas exploitation, during their treatment, transportation, storing and utilization of products, are important sources of air pollution. In the developed industrial countries the portion of hydrocarbon emissions constitutes as much as 9% of the total amount of emissions [20]. Table 5.23 presents data concerning emissions of hydrocarbons from a hypothetical refining plant with a treatment capacity of 5 million t yr, related only to storage and transport of petroleum and by-products in the refining plant [21]. 

Hydrocarbons occurring in oil and natural gas are of great significance for the contemporary civilization, due to their being the most commonly used fuel, on the one hand, and the source of row materials for chemical industry, on the other hand [1], Oil contains (see examples in Figure 2) a considerable amount of alkanes, as well as, aromatic and other hydrocarbons. Methane is usually a major component of natural gas (Figure 3) [2], The distribution of total natural gas reserves (4,933 trillion cubic feet or 1.4 x lo" m )is the following Eastern Europe (40.1%), Africa/Middle East (39.2%), Asia-Pacific (6.6%), North America (6.1%), Latin America (4.1%), and Western Europe (3.9%) [Ic]. 

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