Показатели преломления

где

Х₁ - содержание нафтенов в исходной фракции, вес%

X - содержание нафтенов в деароматизированной фракции (табл.4.4.10 /3/)

А - содержание в исходной фракции углеводородов  ароматического ряда,   вес%

Содержание  парафинов в исследуемой фракции, в вес%

Х₁ - содержание нафтенов в исходной фракции, вес%

X - содержание нафтенов в деароматизированной фракции (табл.4.4.10 /3/)

А - одержание  в исходной фракции углеводородов  ароматического ряда, вес%

Содержание  парафинов в исследуемой фракции, в вес%

 Таблица 2 

Objective analysis of light distillates is consistent quantification of hydrocarbons of various classes and groups. In the products directly obtained by distillation or in the process of going suppression of hydrogen, there are three classes of hydrocarbons: alkanes, cycloalkanes and arenes. The products of cracking and pyrolysis along with these hydrocarbons may also contain unsaturated compounds: alkenes, alkadieny, cycloalkanes and arenes with unsaturated side chains (such as styrene). When the detailed study of the light oil fractions analysis problem is already a quantification or qualitative identification (proof of) separate individual hydrocarbon or heteroatomic compounds (compounds containing sulfur, nitrogen and oxygen) contained in the sample.  
        The main characteristics of petroleum and petroleum products are such parameters as: density, molecular weight, viscosity, flash point, ignition, spontaneous combustion, pour point, cloud point, the temperature of crystallization, electrical and optical properties.  
 
 
DETERMINATION OF REFRACTIVE INDEX  
 
 Refractive index (refractive index) is defined by ¬ lyayut for petroleum products. He describes the ability of the nave ¬ ucts refract the incident light beam at him. The ratio of the sine of the angle of incidence to the sine of the angle of pre ¬ gence of the beam for each petroleum product continuously and is called the refractive index. Determination of the refractive ¬ tive index is based on the effect of limiting the angle at which the total internal reflection. Refractive ¬ termined by the device, called a refractometer.  
Refractive index depends on temperature and wavelength of light (Table 3). The longer the wavelength of the light beam, the smaller the refractive index.  
The refractive index of oil products is usually determined for the yellow sodium line at 20 ° C, respectively refer to n 20D dependence of the refractive index on temperature is expressed as follows  
n 20D = n tD-α (20-t)  
where n 20D - the index of refraction at the analysis, α - a correction factor of 0.0004 to 1 ° C; t - temperature analysis.  
Table 3 - Major sources of light used in refractometry  
Light Source Color Line spectrum line wavelength, nm  
Hydrogen tube  
Sodium vapor lamp  
Hydrogen tube  
Hydrogen tube  
D  
F  
G Red  
Yellow  
Blue (Blue)  
Blue (purple) 656.3  
589.3  
486,1  
434,1  
 
Refractive index of the petroleum product with increasing temperature ¬ ture is reduced. The correction factor α should be used within a temperature range from 15 to 35 ° C.  
According to the refractive index can be estimated purity of individual hydrocarbon, hydrocarbon composition of petroleum fractions. From hydrocarbons smallest value of the refractive index are n-alkanes. With the worsening of the fractional composition of petroleum fractions increases its refractive index. Refractive index - the required value for determining the structural-group composition of fractions boiling in the range 200-540 ° C, the so-called method of n-ρ-M (known as the method of n-ρ-M (the old designation of the density)).  
Control in determining the adsorption group ugleodorodnogo of gas oil and kerosene-oil fractions is carried out on the refractive index. In this case, a paraffin-naphthene hydrocarbons include n 20D fractions less than 1.4900.  
To change the refractive index can be judged on the phase transformations of solid hydrocarbons. In this case, the isotropic liquid phase is characterized by a refractive index, and the anisotropic solid phase - the two refractive indices. Area the appearance of a solid phase in certain temperature interval is characterized by two refractive indices: the liquid and the phases.  
Refractive index is used in various calculation formulas (for example, to determine the density).  
For qualitative and quantitative characteristics of hydrocarbons and their fractions were obtained according to the specific refraction R, the molecular refraction RM, intertsepta refraction Ri, the characteristic factor Lillard F, the relative variance WFC or WFCD, dispersiometri-electric coefficient of DFC or DFCD:  
R = RM =  
Ri = n 20D-(ρ204 / 2); F = M (n 20D-1.4750);  
WFC = WFCD =  
DFC = DFCD =  
where ρ - density of oil products, defined at the same temperature as the refractive index, M - molecular weight mineral oil; coeffi ¬ cient 1.4750 in the formula for the F - limit value of the refractive index of ¬ for a paraffin-naphthene fraction; nF - refractive index for the blue hydrogen line; ps - the index of refraction for the red line of hydrogen, pD - the index of refraction for the yellow sodium line.  
Aromatic hydrocarbons are characterized by the highest values of specific refractive errors.  
Hydrocarbons boiling up to 200 ° C have the following meanings intertsepta refraction Ri aromatic 1.063; naphthalene ¬ Tenova 1.040, 1.046 alkanes.  
Characterization of factor F for alkanes is -8.79, -5.41 alkiltsiklopentanov; alkiltsiklogeksanov -4.43; ditsik-logeksanov -1.0; monocyclic aromatic hydrocarbons ¬ Dov 2.64; tetralin 10,0; naphthalenes 16.5.  
Values dispersiometricheskogo coefficient (DFCD) for various hydrocarbons C24 and C32 are given below:  
NAFTA (bi-and tricyclic) 192-195  
Alkilnaftaliny 320  
Dinaftilalkany 442  
Alkylbenzenes 240-246  
Benzilnaftilalkany 368  
Difenilalkany 292-313  
Alkiltetraliny 288  
Phenylalkyl 269  
Dispersiometrichesky coefficient of paraffin-naphthene fractions boiling up to 300 ° C, equal to an average of 194.4. For aromatic hydrocarbons dispersiometrichesky coefficient can be determined from the dependence:  
D = 194,4 + [(A + 1,5 n) / M] • 103,  
where 194.4 is the average ratio dispersiometrichesky paraffin-naphthenic hydrocarbons, and A-factor, which characterizes the type of aromatic nucleus and n - the number of deputies in the aromatic rings (for petroleum fractions n = 3), M - molecular mass.  
The mean values of factor A:  
Benzene and its derivatives 14.5  
α, ω-Difenilalkany 29  
Diphenylmethane and its arbitrariness-31  
nye  
Alkildifenily 52  
Naphthalene and its derivatives 47  
α, ω-Dinaftilalkany 94  
To determine the refractive index used two types of refractometers: Abbe and Pulfrich. The first type of relative ¬ syatsya domestic Refractometer RLU, IGF-22, CRF-454. Pulfrich refractometer type device is an IRF-23. In laboratory practice, the most frequently used refrakto ¬ meters such as Abbe. For more accurate determinations of the refractive index and dispersion should be used refrakto ¬ meter type Pulfrich.  
Determination of the refractive index refractometer IRF-454  
Instruments, reagents, materials  
Type refractometer IRF-454  
Glass rod or pipette  
Petroleum ether or ethyl alcohol  
 Lint-free tissue paper (tissue)  
Refractometer IRF-454 allows you to determine the refractive index of oil products in the range from 1,2 to 2,0 for a ¬ of D with an accuracy of ± 2-10 ~ 4. The operating principle of a refractometer based on the phenomenon of total internal reflection when light passes the interface between two media with different refractive indices.  
Determination of the refractive index is carried out at dnev ¬ dimensional or electric light. Refractometer and a light source installed so the light shines on the entrance window of the illuminator ¬ relatively prism or mirror, which directs the light into the input window of the measuring prism. For temperature control of prisms and studied petroleum product refractometer connect with a thermostat. Temperature control is carried out with an accuracy of ± 0,2 ° C.  
Before you begin, you should discard the lens flare and clean the surface of the measuring prism. Prism surface cleaned by wiping with a clean soft, lint-free cloth (cloth) moistened with petroleum ether or alcohol. Then with distilled water or test wafer alignment checked by a refractometer at 20 ° C.  
After adjustment for clean polished surface of the measuring prism glass rod or pipette carefully, without touching the prism, causing two or three drops of oil products researched and down lighting prism. Measurement of transparent oil is carried out in transmitted light as it passes through the open window illuminating a prism, with the window closed measuring prism mirror. Eyepiece mounted on a clear visibility of the crosshair. Turning mirrors achieve the best illumination of the scale. Rotate the flywheel lower border of light and shade should be entered in the field of view eyepiece. Upper hand wheel to rotate to the disappearance of color of the boundary line. Watching through the eyepiece, the lower boundary of the flywheel induce chiaroscuro exactly on the crosshairs and the scale of the refractive index read out. Scale 1-10-3. Whole, tenths, hundredths and thousandths of ticks on the scale, and ten-thousandth of estimate by eye.  
For colored and dark oil measuring pro ¬ lead in reflected light.  
Result:  
All oil Kumkol, Kazakhstan.  
In the course of laboratory work were calculated using an IRF-454 refractometer, the refractive indices of diesel fuel additive ionol 0,1%, petroleum ether, the first oil pursuits, cyclohexane.  
1 Indicator drum z = 36.  
Refractive index of cyclohexane - n 20D = 0,4310;  
2 Indicator drum z = 33  
The values of the refractive index of diesel fuel additive ionol 0,1% - n 20D = 1,4640;  
3 Indicator drum z = 30  
Refractive index of petroleum ether - n 20D = 1,398;  
4 Indicator drum z = 33  
The values of the refractive index of the first oil pursuits -  
n 20D = 1,4850.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DETERMINATION OF GROUP AND INDIVIDUAL of gasoline direct distillation  
 
Light fractions of petroleum hydrocarbons  
 
       Alkanes from C5 to C9, included in the gasoline fractions, under normal conditions is a liquid. Based on analysis of individual-cial hydrocarbons emitted from 10 CIS oil, found that gasoline fractions of petroleum, mainly represented by compounds with pro Station alternates. The exceptions are oil fields and oil Anastasievskogo stones, which are isomers with long side chains [3].  
       Analysis of data on the content of individual alkanes in the gasoline fractions of the same boiling range (average of 77 different crudes CIS and the world) showed that in the greatest number is the simplest hydrocarbon, and the following isomer is usually a methyl-substituted in position 2 or 3.  
        Found all 5 isomers of hexane, heptanes from 9 - 7 out of 18 isomers of octane - 16.  
       In the study of different crude oils of gasoline combined method was determined to 90% of hydrocarbons - alkanes, cycloalkanes C5 and C6 and arenes. Some regularities in the distribution of hydrocarbons in gasoline, depending on the type of oil. Gasoline various oils contain about the same set of hydrocarbons, but to a varying number, including 10 hydrocarbons present in gasoline, are in greatest quantity.  
        Alkanes are saturated with hydrogen and compared with hydrocarbons of other classes have a minimum value of density and refractive index that is used for analytical purposes.  
      The general content of naphthenes in many oils dominate over other classes of hydrocarbons. On average, the various oils are present from 25 to 75% polymethylene hydrocarbons of all types.Naphthenes are included in all crude oils and are present in all fractions, and only the most high-boiling oil fractions it decreases by increasing the content of aromatic structures. Particularly rich in cycloalkanes Baku and Emba oil - 40-60%, and in some fractions to 60-80% based on oil. Oils eastern regions of the CIS is much smaller. Their content usually increases as the weighting fraction.Most stable five-and six-membered rings. At elevated temperatures and in the presence of various catalysts naphthenes fall, and isomerized to change the number of carbon atoms in the ring.  
      Distribution of cycloalkanes on types of structures determined by the composition and temperature of oil boiling range. Thus, monocyclic cycloalkanes disappear in fractions of 300-350 º C, bicyclic contained in the fractions from 160 to 500 º C, and their number decreases significantly after 400 º C. Tricyclic found in the fractions above 350-400 º C. This distribution is subject to certain fluctuations, depending on the type of oil. Naphthenic hydrocarbons constitute a large portion of high-boiling oil fractions.  
       At the individual level is difficult to identify a huge number of structural and spatial isomers naphthenes. Therefore, when their investigations are widely used structural-group methods.  
             The content of aromatic hydrocarbons in the medium fractions are always somewhat higher than in the gasoline fraction from the same oil, and ranges from 15-35%. In the higher oil fraction revealed a more complex polycyclic aromatic hydrocarbons with three, four and five fused benzene rings.  
Arena shows in petroleum benzene and its homologues and derivatives of bi-and polycyclic hydrocarbons. In the oils contained hydrocarbons and hybrid, containing not only the aromatic rings and the alkanoic chain, but also saturated cycles.  
    Arena oil studied better than other classes of hydrocarbons.Many individual arenas were isolated from petroleum fractions by using methods based on the use of high reactivity, selective adsorption, solubility in polar solvents, high temperatures, melting of arenes.  
Arenas are much more vysokeuyu density and refractive index than the alkanes and cycloalkanes.  
Crystallization temperature (melting point) is higher, the more the symmetric molecule and the smaller they can pack in the crystal lattice.  
Boiling points of isomeric arenes differ slightly. The highest boiling point have isomers with adjacent alkyl groups (o-xylene, gemimellitol, prenitol) having the most-large dipole moments.  
Viscosity and density of alkylbenzenes increases with the number of methyl groups, and the viscosity index is reduced. The density of polymethyl benzene derivatives is also higher than alkylbenzenes with the same number of carbon atoms because of their increased intermolecular interaction.  
                   The presence of aromatic hydrocarbons in gasoline is highly desirable, since they have high octane numbers. Their presence in significant amounts in diesel fuel affects the process of combustion. Polycyclic aromatic hydrocarbons with short side chains, should be removed from the cleaning process, since their presence is detrimental to performance of lubricating oils.  
Arena characterized by the worst flammability, low values of cetane numbers. For example, the cetane number of 1-methylnaphthalene is zero. Therefore, fuels with high content of arenes in high-speed diesel engines do not apply.  
       
 Using the latest in determining the quantitative content of hydrocarbons in the fraction of gasoline based on the fact that the aniline point dramatically different for methane, naphthene, aromatic hydrocarbons, boiling within the same temperatures.Therefore, the value of aniline point, defined as the temperature of the mutual dissolution of mineral oil and aniline, together with the refractive index, density, etc., is one of the characteristics of hydrocarbons. The lighter hydrocarbons dissolved in aniline, the lower the aniline point. The presence of aromatic hydrocarbons in gasoline reduces the value of aniline point compared with dearomatised gasoline, ie, Gasoline containing only methane and naphthenic hydrocarbons.  
 
  Apparatus Reagents  
Standard device "Tube Gasoline direct distillation  
in a test tube with a rubber sleeve "Sulphuric acid conc.  
Stirrer, a thermometer at 150 º C Aniline  
Stove, sulfator  
Chemical cups in 500ml solvent  
DEFINITION Aniline points by Equal volumes  
 The content of aromatic hydrocarbons calculated by the depression of temperature of dissolution of gasoline in aniline (Aniline Point) is locally T | and after the removal of aromatic hydrocarbons T2 and aniline coefficient K, whose value is determined experimentally. According to this method are taken equal volumes of the investigated gasoline and aniline. Removal of aromatic hydrocarbons produced by the sulfonation and with the help of a liquid - adsorption chromatography (adsorbent-silikatel grade AC). Calculation of the percentage of aromatics is carried out according to the formula  
                                  A = K • (T2 - T1)  
where K - aniline ratio equal percentage of aromatic hydrocarbons, leading to reduction of aniline point at 1 ° C.  
The value of the aniline ratio depends on the following factors:  
1) the nature of aromatic hydrocarbons,  
2) the fractional composition of gasoline  
      3) the chemical composition of the non-aromatic fractions  
        4) the concentration of aromatic hydrocarbons.  
         
 
 Table 1  
 
 
 
 
 
 
 
 
 
 
   
 
 
 
 
 
 
          
 
   
 
 
 
   
 
 
 
   
 
 
 
   
   
 
           
 
           
where  
 
 
 
 
        
 
 
 
 
 
   
            
 
 
 
 
60  
59  
58  
57  
56  
55  
54  
53  
52  
51  
50  
49  
48  
47  
46  
45  
44  
43  
42  
41  
39  
38  
36  
 
36  
39  
42  
44  
47  
50  
52  
55  
56  
61  
64  
 
70  
 
75  
77  
80  
82  
85  
90  
92  
95  
 
45  
49  
53  
56  
60  
63  
 
70  
74  
74  
79  
84  
87  
90  
93  
97  
100  
-