Express-method of identifying detergent additives in automobile petrol

FIELD: chemistry.

SUBSTANCE: dispersion-indicator composition is prepared, for which purpose hydrochloric acid and water-alcohol solution of bromophenol blue are introduced into distilled water, obtained composition is combined with petrol sample, into which methyl-tert-butyl ether is preliminarily added, mixture is mixed and settled at room temperature, volume of foamy layer of blue-light blue colour is measured at the boundary of “petrol-water" separation, and if its value is not less than 1 cm3 conclusion about detergent additive in petrol is made.

EFFECT: acceleration of identification with high degree of its reliability.

1 ex, 5 tbl


The invention relates to methods of quality control of gasoline (AB), in particular to a rapid method of determining the content of detergents in AB, and can be used in laboratories, fuel, gas stations, enterprises engaged in receiving, storing, issuing, quality control of gasoline.

During use in engines of motor gasoline are formed deposits in fuel tanks, the power supply system, the combustion chamber, rods and plates of the intake valves in the crankcase. Deposits alter thermal regime of the engine, reduce fuel, wear and reliability.

To ensure established quality requirements for motor gasoline use additives that improve the performance of engines providing persistence quality, reducing deposits in the combustion chamber, reducing the level of toxicity of exhaust gases [1 - A. S. Safonov, A. I. Ushakov, A. C. Oreshenkov. The quality of automotive fuels. Operational properties. The quality requirements. Testing methods. NECC, 2006, S. 148].

The most effective way of dealing with the formation of deposits in the intake system of the engine is the use of special detergents. With constant use the gasoline with detergent additives possible fuel savings of up to 2-3%. In addition, adding to the gasoline detergent additives increases the mileage of the car without disturbing the adjustment reduces the content of carbon monoxide in the exhaust gases [1 - S. 156].

Detergent additives are oil - and maslosoderzhashchimi surface-active substances (surfactants) with sufficient thermal-oxidative stability, which manifest themselves on the phase boundary metal-hydrocarbon-resinous deposits, contributing to the translation of resinous deposits on the metal in a liquid hydrocarbon medium. Most detergents are complex nitrogenous and oxygenated compounds obtained by the reaction of higher fatty acids, alcohols, amines, aldehydes and other petrochemical products. The mechanism of action of detergents is based on the introduction of surfactant molecules into the particles of the contaminants adsorbed on the surface, a change in volume of fuel and solubilization within the micelles formed by the surfactant molecules. While detergents also have a dispersing effect, preventing the planting of contaminants on the metal surface of the engine and fuel equipment [2 - Danilov A. M. additives and additives. M.: Chemistry, 1996, S. 131].

Detergent additive can be introduced into the gasoline at all stages of its production, storage and application. In terms of refinery additives trying to enter h for whom ordinary is not to increase the number of grades of gasoline and therefore, tanks, communications, etc. today is widely practiced introduction of additives to the tank farms and filling stations during shipment of fuel to the consumer. In this case, the additive is metered into the stream of fuel or poured into the tank of the tank truck: mixing occurs in the pumping process. [3 - Journal "oil Refining and petrochemical industry" №3 2010 S. 22-23;].

In the current regulatory and technical documentation for petrol determination of the presence of detergents is not provided, the conventional methods are not available. The definition of detergent additives in gasoline should be implemented in order to ascertain whether or not they (detergents) were introduced into gasoline during shipment or refueling and to check compliance with the cleansing properties of gasoline, which, as a rule, are made in the accompanying documentation.

The authors goal was to develop a simple to implement, does not require sophisticated analytical equipment, as well as budget in economic terms, a rapid method of determining the presence of detergents in motor gasoline with acceptable accuracy and precision.

In the analysis of scientific-technical and patent literature have been identified technical solutions, partially solving the task of determining the presence of detergents in motor gasoline.

From the local method of quantitative determination of detergents in motor gasoline, which is based on measuring the peak areas in the field 1103 cm-1in Fourier transform infrared spectra of solutions of detergents on the basis of high molecular weight Mannich bases in methylene chloride. The spectra were obtained using a Fourier transform IR spectrometer Tensor 227 "BRUKER" or "Nicolet 380" as spectrometers of high resolution. Survey spectra were carried out in a demountable liquid cell with glass KBr, spacer thickness was 0.5 mm [3 - n-21-26].

There is also known a method of determining the presence of detergents in motor gasoline, according to which the presence of detergents is determined by the difference of the number of pitches before and after washing with n-heptane, using the method of determining the washed resin (resin remaining after washing with n-heptane). [EN P # 2497111, G01N 33/2 (2006.02)].

The analysis of the above methods for the determination of detergents in AB shows that they have several disadvantages associated with the need to use expensive equipment, the duration of the test time, which eliminates the possibility of operational use at petrol stations, oil depots and other facilities that consume gasoline.

The authors found no rapid methods for the determination of detergent additives in gasoline, and any of the above methods may be adopted for the prototype, as it solves the same problem - the definition of a detergent prisa is key.

The technical result of the invention is to reduce the time of determination of detergents in motor gasoline, without compromising on accuracy.

This technical result is achieved in that in the method of determining the presence of detergents in motor gasoline, according to the invention is prepared dispersible indicator composition in distilled water is injected in 0.1 n hydrochloric acid and water-alcohol solution of bromophenol blue in a volume ratio of 1:0.01 to:0,001, the resulting composition is combined with 40±2 cm3samples of gasoline, which previously added methyl tert-butyl ether (MTBE) in an amount of 0.1 sample volume, the mixture is stirred for 60±5 seconds, defend at room temperature for 10-15 min, measured at the interface of the volume of the foam layer of the blue color, the meaning of which is not less than 1 cm3judge the presence of a detergent additive in gasoline, the original volume of distilled water take is equal to the sample volume of gasoline with methyl tert-butyl ether.

The essence of the method consists in the extraction detergent additive weakly acidic solution of 0.1 n hydrochloric acid (HCL) (GOST 3118-77) in the presence of the indicator bromophenol blue (PLS) (TU 6-09-5421-90) with subsequent fixation of its existence. For this purpose were selected conditions extraction detergents from AB received what I emulsion and selection of the indicator, having a color transition upon contact with the emulsion containing detergent additives. In addition, the studies revealed the influence of different quantities of MTBE by volume of the foam layer at the interface of gas-water, which led to the determination of the minimum sufficient amount of MTBE is added to a sample of gasoline is 0.1 of the volume of the sample.

To justify operating parameters and the set of methods of the claimed method were prepared samples of gasoline with different detergents additives (table.1).

The method is implemented as follows.

Example 1. In a sample of 40 cm3gasoline for sample No. 1 (PL.1) add 4 cm3MTBE. Prepare dispersible indicator composition in water volume 44 cm3add to 0.44 cm30.1 n HCL and 0.04 cm3(4 drops) indicator bromophenol blue. Next, a sample of the gasoline additive MTBE is mixed with the received dispersible-indicator composition and exercise dilution (e.g., by shaking) within 60 sec. The resulting mixture assert within 15 minutes, get a clear boundary "gasoline-water, where visible foam layer. Record the volume frothy layer blue color.

The above steps of example 1 were carried out with all the prepared samples No. 2 to No. 4), the car is gasoline. The results obtained are presented in table 2.

As can be seen from table 2, using a rapid method confirmed the presence of detergents in the samples No. 1 to No. 3 and sample No. 4.

Modal parameters and the ratio of reagents in the present method is obtained when conducting research using samples on the table.1 and many other artificially prepared samples.

The results of experimental studies on the selection of parameters for the determination of detergents in motor gasoline are presented in table. 3 and 4.

As can be seen from the test results, the magnitude of the foam layer depends on the time of settling of the foam layer and the volume of 0.1 n HCL, part dispersible indicator composition. It is established that the formed foam during sedimentation decreases, and after 10 minutes almost stabilized (see line 4, 5, 9, 10, 14, 15 in table.3), and the quantity of foam sufficient for its measurement, the best at 0.4 cm3of 0.1 n HCL (see lines 13-15).

Dispersible indicator composition is obtained during the research a liquid mixture of distilled water, 0.1 n hydrochloric acid and PLS taken in the ratio 1:0,01:0,001. At other values of the ratios do not show a clear foam layer.

Time peremeci the project for 60±5 seconds so it was chosen based on the magnitude and time stability of the foam layer. With less time mixing the foam could not be generated.

Identified the need for additional introduction of MTBE in samples of gasoline confirmed the influence on the increase of the foam layer. The results of the impact assessment of the content of MTBE on the size of the foam layer are presented in table 4.

The optimal number of MTBE selected 4 cm3(0.1 of the volume of the sample), and the introduction was carried out directly in the cylinder with AB and other necessary reactants before mixing. Adding MTBE significantly increases the amount of frothy layer that facilitates its fixation, especially for gasoline, which in its composition does not initially contain MTBE (Pulsar-92).

The claimed method in the laboratory were tested with real samples of automotive gasoline Pulsar-95, the production company TNK-BP and Regular-92 (Ryazan refinery). The content of additives in the samples to confirm the reliability was checked by the method of IR-spectroscopy (3 - n-22-23). The results are presented in table 5.

The results presented in table 5, confirm that the invention is reliable, in addition, laboratory equipment and chemical reagents used to implement this method, enable re is to be applied as in a stationary, mobile laboratories, and the immediate application of AB (gas stations, oil depots and tankers) within a short interval of time (10-15 minutes).

A rapid method of determining the presence of detergents in motor gasoline, characterized in that the prepared dispersible indicator composition in distilled water is injected in 0.1 n hydrochloric acid and water-alcohol solution of bromophenol blue in a volume ratio of 1:0.01 to:0,001, the resulting composition is combined with 40±2 cm3samples of gasoline, which previously added methyl tert-butyl ether in an amount of 0.1 of the volume of the sample, the mixture is stirred for 60±5 seconds, defend at room temperature for 10-15 min, measured at the interface of the gasoline-water volume of the foam layer of the blue color, the meaning of which is not less than 1 cm3judge the presence of a detergent additive in gasoline, the original volume of distilled water take is equal to the sample volume of gasoline with methyl tert-butyl ether.


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