CC BY
14UOT 665753.4
Aliyeva A.A.
Associate Professor, Doctor of Philosophy in Chemical Sciences,
Faculty of Chemical Technology, Department of Petrochemical Technology and Industrial Ecology, Azerbaijan State Oil and Industry University, Baku, Republic of Azerbaijan Mehdiyeva S.Z. Master Student, Faculty of Chemical Technology, Department of Petrochemical Technology and Industrial Ecology, Azerbaijan State Oil and Industry University, Baku, Republic of Azerbaijan Алиева А. А.
доцент, доктор философии по химическим наукам, кафедра нефтехимических технологий и промышленной экологии,
химико-технологический факультет, Азербайджанский государственный университет нефти и промышленности,
Баку, Азербайджанская Республика Мехтиева С.З. магистрант,
химико-технологический факультет, кафедра нефтехимических технологий и промышленной экологии, Азербайджанский государственный университет нефти и промышленности,
Баку, Азербайджанская Республика E-mail: aynura82@yahoo.com
Effect of oxygen-containing additives on the fuel properties Влияние кислородсодержащих присадок на свойства топлива
Abstract: This article is devoted to the study of the effect of additives on the base of oxygenates on the gasoline characteristics. Ethylcellosolve, ethylcarbitol, butylcellosolve and butylcarbitol added
into straight-run gasoline obtained from atmospheric unit with various concentrations. Then the octane number of fuel sample with added oxygenates was defined. Synergistic mixtures which include the most effective oxygenates not only improve the properties of fuel, but also decrease their concentration that causes the reduction of the effect on physicochemical properties and performance characteristics of fuels. Synergistic effects were found in the combined action of cellosolves and carbitols, which lead to the boosting of straight-run gasoline octane rating according to research method up to 9 unit.
Аннотация: Данная статья посвящена изучению влияния присадок на основе оксигенатов на характеристики бензина. Этилцеллозольв, этилкарбитол, бутилцеллозольв и бутилкарбитол добавляют в прямогонный бензин, полученный из атмосферного агрегата, с различными концентрациями. Затем определяли октановое число образца топлива с добавлением оксигенатов. Синергетические смеси, в состав которых входят наиболее эффективные оксигенаты, не только улучшают свойства топлива, но и снижают их концентрацию, что приводит к уменьшению влияния на физико-химические свойства и эксплуатационные характеристики топлива. Обнаружены синергетические эффекты при совместном действии целлозольвов и карбитолов, которые приводят к повышению октанового числа прямогонного бензина по методике исследования до 92 единиц, влияние кислородсодержащих присадок на свойства топлива.
Keywords: straight-run gasoline; catalyst; oxygenates; fuel; synergistic mixtures.
Ключевые слова: прямогонный бензин; катализатор; оксигенаты; топливо; синергетические смеси.
Introduction. Nowadays the rate of environmental pollution, especially products of incomplete combustion of motor fuels requires strict regulation of the requirements for the quality of modern motor fuels. Gasolines used in vehicles are characterized by its blended composition with various components [1]. Different types of fuel additives are used in order to improve gasoline performance in vehicles and to decrease specific emissions.
Additives, especially oxygenates in gasoline fractions increase their detonation resistance. More over increasing the concentration of oxygen in the fuel causes to a more complete combustion of hydrocarbons, in fuel-air mixture combustion heat
declines and consequently promotes a faster removal of heat from the chamber, therefore the maximum combustion temperature reduces [2, 3].
Oxygen containing additives are characterized by boosting the octane number of gasoline and satisfactory combustion characteristics. In other words the use of oxygenates leads the reduction of exhaust gases toxicity and prevents increasing of the content of unsaturated hydrocarbons, mainly arens [4].
The most common oxygenate additives are methyl and ethyl tert-butyl ethers diisopropyl ether methyl, ethyl, isopropyl and n-butyl alcohols. All oxygenates boost the octane number of gasoline, while excessively high concentration of oxygenates leads to the changes in fractional composition of fuel and decreases the energy efficiency of engines. Therefore creation of synergistic mixtures which comprises of powerful oxygen containing additives at lower concentrations increase the octane number of gasoline and can be used as a high-octane component to motor fuels [4, 5].
Experimental Part
A straight-run gasoline fraction obtained from atmospheric distillation of crude oil with the initial boiling point and final boiling point 200 °C was selected as main sample. The sample on which experiments were conducted did not contain any components and additives.
Table 1 — Physicochemical properties of gasoline fraction
№ Fractional composition Sample
1 Initial boiling point. °C 39
2 10% of gasoline is distilled at the temperature, °C 51
3 50% of gasoline is distilled at the temperature, °C 84
4 90% of gasoline is distilled at the temperature,°C 170
5 Final boiling point,°C 200
6 Octane number according to research method 78
7 Isoparaffins, % wt. 34,6
The following oxygen-containing compounds were considered as antiknock additives: acetone, anisole, ethyl cellosolve (EC), ethyl carbitol (EC), butyl cellosolve (BC), butyl carbitol (BC). Methyl tertiary butyl ether (MTBE) was taken as a comparison and analog to antiknock additive, the physicochemical properties of which are given in Table 2.
Table 2 — Physicochemical properties of MTBE
№ Physicochemical properties Indicator
1 Density at 20 0C, kg/m3 746
2 Boiling point, 0C 55
3 Flash point, oc -27
4 Self-ignition temperature, oc 443
5 RON, units 125
6 Solubility in water, at 20 oc, % wt. 1,3
7 Limiting rate of content in gasoline, % wt. 15
Samples of oxygenate compounds were added individually with various rising concentrations to the initial sample of the gasoline fraction with an RON = 78 units. Then the octane numbers of fuel with oxygenate additives were determined. Additives to the original gasoline fraction were injected from 0.25 to 7%.
Physicochemical properties of blends are analyzed by the standard American Society of Testing and Materials (ASTM) method. Density, viscosity and corrosion properties of samples were determined.
Results and Discussion
The octane rating of gasoline has changed depending on the concentrations of the studied oxygenate additives. A noticeable effectiveness was observed by adding of
carbitols, then cellosolves, and then acetone and anisole. Furthermore the same tendency was observed in terms of an increase of octane number. The content of sulfur depending on the concentration of additives decreases complying with an increase the amount of additives. However the change in the aromatic content differs slightly.
When two or more additives are mixed together in different ratios, as a rule, a synergistic effect is manifested in their joint action. In order to reveal the effect in the boosting of octane number, two-component mixtures of ethyl cellosolve with butyl cellosolve (EC + BC) and ethyl carbitol with butyl carbitol (EC + BC) were studied in various ratios and the total concentration of the additive in gasoline was 1% wt.
Figure 1 — Dependence of the change of gasoline octane rating on the ratio of components in the additive (ethyl cellosolve with butyl cellosolve (EC + BC)): (ethyl carbitol with butyl carbitol (EC
+ BC))
According to the Figure 1 at ratios (EC + BC): (EC + BC) 30:70 and 70:30 the octane number of gasoline increases to 92.4 units. The second extremum is in the area of ratios 70:30 ^ 80:20, while RON= 92.3 units. Thus mixing of cellosolves and carbitols increase the octane rating of tested gasoline.
Comparison of the results (Table 3.) complying with MTBE showed that even up to 5% wt. concentration in gasoline does not increase the detonation resistance of the fuel as a mixture of cellosolves and carbitols allows. Their concentration in gasoline is not more than 1%. However a sharp increase in the sensitivity of the tested gasoline fraction to MTBE occurs only at a high concentration of the additive.
Table 3 — Variation in the octane number of the gasoline fraction depending on the concentration of MTBE
Concentration of MTBE, % mass. 0% 1,0% 2,0% 5,0% 10,0%
MON, unit 76 81 82 83,5 86,9
RON, unit 28 84,2 86 90 95,0
Conclusions
1. Tested oxygenate additives such as cellosolves and carbitols significantly increase the octane number of straight-run gasoline fraction.
2. A synergistic mixture at the found optimal ratios leads to production of high-octane gasoline with an octane rating of at least 92 units (according to the research method). Unlike to MTBE synergistic mixture boost the octane rating of gasoline fraction at lower concentrations.
References
1. Hidalgo J.M., Zbuzek M., Cerny R. // Current uses and trends in catalytic isomerization, alkylation and etherification processes to improve gasoline quality // Central European Journal of Chemistry, — 2014, — V. 325, — №1, — p. 1-13.
2. "Advanced Catalysis Processes in Petrochemicals and Petroleum Refining: Emerging Research and Opportunities, — 2019, — p. 257.
3. Kapustin V.M. Petro— leum and alternative fuels with additives, — 2008, — 232 p.
4. Kozin V.G., Solodova N.L., Bashkirtseva N.Yu. Modern technologies for the production of component motor fuels, Kazan, — 2003, — p. 263.
5. Sobchinskiy A.I., Zhukova I.Y., Tyaglivaya I.N. «Research of Isobutyl Oil as Antiknock Additive to StraightRun Gasoline», International science and technology conference "Earth science", — 2019, — p. 272.
