INCREASING THE DETONATION STABILITY OF AUTOMOTIVE GASOLINES BY BASIC SYNERGISTIC MIXTURES OF OXYGEN COMPOUNDS

ABSTRACT

This article examines the influence of local automobile gasolines AI-80, AI-91 and n-heptane on the detonation stability of standard hydrocarbon mixtures with different isooctane and toluene contents. The results of the research are of great scientific and practical importance in the production of local low-octane gasoline and gasoline additives that meet modern environmental requirements.

АННОТАЦИЯ

В данной статье исследуется влияние местных автомобильных бензинов АИ-80, АИ-91 и н-гептана на детонационную стабильность стандартных углеводородных смесей с различным содержанием изооктана и толуола. Результаты исследований имеют большое научное и практическое значение при производстве местных низкооктановых бензинов и присадок к бензинам, отвечающих современным экологическим требованиям.

Keywords: gasoline, isooctane, toluene, n-heptane, methyl tert-butyl ether (MTBE), methyl tert-amyl ether (MTAE), detonation stability

Ключевые слова: бензин, изооктан, толуол, н-гептан, метил-трет-бутиловый эфир (МТБЭ), метил-трет-амиловый эфир (МТАЭ), детонационная стабильность.

Car gasoline is a petroleum product that is widely produced in the world and requires relatively complex technologies in terms of production technology compared to other petroleum products. Also, today, the worsening of the environmental situation in the world is the reason for the development of more serious environmental requirements for automobile gasoline.

The problem of atmospheric pollution with fuel combustion products required restrictions on the content of the most dangerous sulfur and aromatic compounds in fuel. The most optimal processes for the production of motor gasoline with improved environmental characteristics are: catalytic cracking, isomerization, alkylation devices and other modern hydrocatalytic processes that allow reducing the amount of sulfur in the motor gasoline obtained with the help of a catalytic cracking unit.

Analysis of literature on the topic (Literature review). The world's major car and engine manufacturers have combined their proposals on the composition of gasoline and published them in the Worldwide Fuel Charter. Based on the quality of the fuel, it was divided into four different environmental categories [1-3]:

Category 1 – minimum standards set for the content of toxic gases or non-existent markets;

Category 2 - markets with serious requirements or restrictions on the content of toxic gases;

Category 3 – markets with high requirements or restrictions on the content of toxic gases;

Category 4 - markets with the highest requirements or restrictions on the content and quantity of toxic gases.

lists some physico-chemical, colloidal and operational parameters of motor gasoline recommended by the World Fuel Charter [4].

After such serious environmental demands, the oil refining industry around the world is going through the biggest transition since its inception, today in the direction of producing the most environmentally friendly fuel.

It is impossible to achieve the technical-economical and ecological indicators of engines without improving the colloidal-chemical, physical and operational properties of automobile gasoline. These properties are achieved by new methods of improving various gasoline components, introducing oxygen-preserving compounds and various functional devices into the composition of gasoline [5-7].

Table 1.

Some physico-chemical, colloidal and operational properties of motor gasoline recommended by the World Fuel Charter

It is not possible to assess the degree of chemical and hydrocarbon structural changes of gasoline, the effect on engine performance, and the quality of gasoline without accurate and reliable determination of many properties. Therefore, the requirements and controls on the quality of gasoline are constantly increasing, and modern gasolines today have various engine, physico-chemical, and physical parameters that can be determined [8-10].

On the basis of existing technologies, the only optimal way to produce gasoline that meets serious environmental requirements and to increase its resource is to search for new additives that increase the octane number. The second promising direction of research is the search for rational approaches to their application, namely:

• joint use of oxygenates and additives based on aromatic amines to ensure a synergistic effect;
• determination and selection of the optimal chemical composition of gasolines that increase the effectiveness of additives that increase the octane number;
• determination of alternative concentrations of oxygenated compounds and motor gasoline.

Research methodology. The following research objects were used: AI-80, AI-91 brand automobile gasoline produced at the BNQIZ plant, isooctane, toluene, heptane and samples mixed with them in different proportions, methyl-tert-amyl ether, methyl-tert-butyl ether.

Detonation stability of new gasoline compositions - GOST 8226-82 determined according to [11].

Analysis and results. At the first stage of our scientific research, isooctane and heptane were mixed, and a hydrocarbon mixture was prepared with an octane number of 80.8 points according to the research method. In this sample, the isooctane concentration is 70%, and the heptane content is 30%. Then MTBE and MTAE were mixed to this sample in amounts of 5, 10 and 15%, and the octane number of these samples was determined.

At the same time, a mixture of 68% toluene and 32% heptane was also prepared and the effect of MTBE and MTAE on the octane number of this mixture was also studied. The main purpose of preparing such a mixture is to determine the difference in the effect of MTBE and MTAE on the octane number of gasoline samples under the same conditions and with the same composition, and to determine the difference in the detonation stability of these oxygenates to aromatic hydrocarbon mixtures and isoparaffin hydrocarbon mixtures. Because the nature of chemical reaction of oxygen compounds to isoparaffin and aromatic hydrocarbons is different.

The effect of MTBE on the detonation stability of reference compounds is presented in Figure 1 below.

As can be seen from this plot, the octane number of the hydrocarbon blends increased with the addition of MTBE. However, the addition of MTBE at the same concentration to these mixtures affected the two samples differently. When MTBE was added up to 15%, the octane number of the Isooctane+n-heptane mixture increased by 5.4 points, while the octane number of the Toluol+n-heptane mixture increased by 9.4 points. These results show that esters have a positive effect on the detonation stability of relatively aromatic hydrocarbon mixtures.

Figure 1. Effect of MTBE on the detonation stability of mixtures of isooctane and toluene with n-heptane

The effect of MTAE on the detonation stability of benchmark mixtures is presented in Figure 2 below.

Figure 2. Effect of MTAE on the detonation stability of mixtures of isooctane and toluene with n-heptane

The results of the research in the chart above are the effects of MTAE on the detonation stability of various benchmark hydrocarbon blends, and the effect of MTAE on the detonation stability of these hydrocarbon blends is lower than that of MTBE. This can be explained by the fact that the octane number of MTAE (in the research method - 99) is lower than the octane number of MTBE (in the research method - 102).

In the next stage of our ban, the effect of MTBE and MTAE on the detonation stability of domestic AI-91 and AI-80 brand automobile gasolines was studied. The results obtained are given below.

Figure 3. Effect of MTBE on detonation stability of AI-80 and AI-91 brand gasolines

As can be seen from the graphs above, MTBE and MTAE have different effects on the detonation stability of domestic motor gasolines. In this case, the influence index of these esters on the detonation stability of local low-octane motor gasoline is much higher than that of high-octane AI-91 commercial motor gasoline. This can be explained by the fact that the octane number of these oxygenates is close to the octane number of AI-91 gasoline.

Figure 4. Effect of MTAE on detonation stability of AI-80 and AI-91 brand gasolines

Conclusions and recommendations. The results of our research show that it is possible to increase the octane number of automobile gasoline with the help of MTBE and MTAE, but it is necessary to add them in a large concentration in the composition of automobile gasoline obtained from these facilities and domestic automobile gasoline. Therefore, we believe that it is appropriate to obtain a package of synergistic oxygen additives with a complex composition and to study their effect on the detonation stability of automobile gasoline, adding other types of oxygen additives with a higher octane number compared to these ethers in further scientific research.

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