The control questions

1. Physical methods of separation, isolation and analysis of hydrocarbon mixtures

2. What types of chromatography do you know?

3. What indicators related to the optical properties of the oil?

4. Give the definition of the following basic parameters: density, flash point, ignition temperature and self-ignition.

Lecture 3.

Methane hydrocarbons, oil content, oil fractions and their physical and chemical properties. The gaseous, liquid and solid paraffins oil. Naphthenic petroleum hydrocarbons, their physical and chemical properties. General characteristics of unsaturated hydrocarbons of petroleum and petroleum products and methods of their determination.

Plan of the lecture

1. Characteristics of methane hydrocarbons

2. Characteristics of naphthenic hydrocarbons

3. Characteristics of unsaturated hydrocarbons

1. Paraffinic hydrocarbons (alkanes, methane hydrocarbons) are a series of rich, saturated hydrocarbons C_nH_2n+2, they occupy an extremely important place among the petroleum hydrocarbons. Paraffinic hydrocarbons are gaseous, liquid or solid. Gaseous compounds contain a chain of 1 to 4 carbon atoms (C1-C4) and part of the free and natural gas (methane, ethane, propane, butane, isobutane). In this case, natural gas represented exclusively paraffinic hydrocarbons and often in their composition is dominated by methane. Compounds containing 5 to 15 carbon atoms (C5-C15) are liquid substances. Normal alkanes since hexadecane (C16) are solids. They at ordinary temperature may be in the crystalline state or dissolved in an oil and a high boiling fractions.

Paraffinic hydrocarbons contained in the oils in an amount of 25-30% (not including dissolved gases). Given the hydrocarbons present in a dissolved state, the content of paraffinic hydrocarbons is increased to 40-50%, and in some oils, it is 50 to 70%. However, there is oil in which the content of paraffinic hydrocarbons is only 10-15%.

Gaseous paraffinic hydrocarbons. Hydrocarbon gases, depending on the fields and methods of production are divided into natural, and passing gas condensate fields. The first type includes natural gas extracted from pure gas fields and consisting mainly of methane with small amounts of ethane, propane, butane, pentane vapor is even rarer, as well as non-hydrocarbon gases: carbon dioxide, nitrogen, and very rarely - hydrogen sulfide.

Gases containing 93-99% methane with small amounts of paraffinic hydrocarbons to C4 inclusively referred to as dry and gases containing paraffin hydrocarbons with more carbon atoms are called fatty C6. Most of the deposits of natural gas refers to the so-called dry gases.

The hydrocarbon composition of light oil. By liquid hydrocarbons include paraffinic hydrocarbons, having from C5 to C15, i.e. from pentane to pentadecane. Hydrocarbons from pentane to decane isomers with all their boiling points are to gasoline.

Solid paraffins. Alkanes C16 and higher under normal solids (paraffins ceresins).

Paraffin - a mixture of solid hydrocarbons of the methane series preferably with admixture of the normal structure of branched alkanes (ceresin), as well as compounds containing a long chain alkane or cycloalkane such arene nucleus.

2. Naphthenic hydrocarbons basically have a closed loop structure of the methylene groups (CH2) x, and therefore closed loop are to be considered saturated, despite the formula - CnH2n, which is also responsible olefins. Naphthenic hydrocarbons (naphtha, cycloalkanes tsiklany) define a special place in the series of oil as natural organic compounds, and among caustobiolites; their content in the oils range from 25 to 75% (wt).

The name "cyclanes " (from cycloalkanes) emphasizes the closeness of their basic properties of alkanes, i.e.with saturated hydrocarbons with an open chain of atoms - with paraffin hydrocarbons. Naphthenic hydrocarbons are found in all crude oil fractions. Their content is usually grows weighting fractions, and only in the most high-boiling oil fractions it falls due uveliche¬niya amounts of aromatic structures.

The average oil comprise from 25 to 75% naphthenes. Light oils contain methane, about three times less than these hydrocarbons than the naphthenic oil where their content in some cases as high as 80% at much reduced number of paraffinic hydrocarbons.

3. Unsaturated (unsaturated) hydrocarbons (alkenes, di -, three - and polyenes, alkynes) in crude oil and natural gas are not available. They are formed in the refining processes. Unsaturated compounds are the most important raw material for the petrochemical and organic synthesis.

Unsaturated hydrocarbons produced in the two cases: in processes where they are by-products, and in special, purpose of which is their maximum output. In the first case the thermal and catalytic cracking, reforming and coking of oil residues, with the purpose - the production of fuels and petroleum coke. In the second case - a pyrolysis polymerization of low molecular weight alkenes, alkanes and dehydrogenation of synthesis of higher alkenes in the presence of organometallic catalysts.

The control questions

1. The main components of paraffinic hydrocarbons

2. The methane hydrocarbons and their role in the composition of oil

3. Chemical and physical properties of naphthenic hydrocarbons

4. Paraffin ceresins