Gasoline formulation

Future technology developments in paraffin alkylation will be greatly influenced by environmental considerations. The demand for alkylate product will continue to increase because alkylate is one of the most desirable components in modern low emission gasoline formulations. Increased attention will be focused on improving process safety, reducing waste disposal requirements, and limiting the environmental consequences of any process emissions. 

Improve the characteristics of a fuel. For example, a lower octane naphtha fraction is reformed to a higher octane reformate product. The reformate is mainly blended with naphtha for gasoline formulation or extracted for obtaining aromatics needed for petrochemicals production. 

The Clean Air Act Amendment (CAAA), passed in November 1990, has set new quality standards for U.S. gasoUne. A complete discussion of the new gasoline formulation requirements can be found in Chapter 10. 

An experimental investigation of equilibrium behavior of the systems composed of methylcyclohexane + ethylbenzene + methanol was carried out at 288.2 K. The liquid-liquid phase diagrams exhibit type 1 systems and indicate that methanol is totally miscible with the gasoline in a wide interval. Therefore, methanol may be considered as a good candied in gasoline formulations for vehicular fuels. 

Figure 13.7 shows the structural formulas of benzene and its major hydrocarbon derivatives. These compounds are very significant in chemical synthesis, as solvents, and in unleaded gasoline formulations. 

The main use of MTBE is as an octane booster in gasoline formulations. Table 2.1 (above) compares octane number and boiling points of some tertiary ethers and hydrocarbons. The volatility is another important property of gasoline components. In fact, the lower volatility of ETBE is an advantage with respect to MTBE. Another (smaller scale) application of MTBE is the synthesis of high purity isobutene by cracking MTBE over amorphous silica-alumina. This isobutene serves as a monomer for polyisobutene. 

The main use of MTBE is as an octane booster in gasoline formulations. Table 2.1 (Section 2.2.1) compares octane number and boiling points of some tertiary... 

About half of the benzene produced as a chemical feedstock is for styrene production, followed by large fractions for phenol and cyclohexane-based products. As much as half of the toluene produced is converted to benzene, depending on the price and demand differential. The largest use of toluene itself is as a component of gasoline. Much smaller amounts are used as a solvent, or in the manufacture of dinitrotoluene and trinitrotoluene for military applications. Xylenes are also used in gasoline formulations and function as octane improvers like toluene. para-Xylene and o-xylene are the dominant isomers of value as chemical feedstocks, for the production of terephthalic acid (and dimethyl terephthalate) and phthalic anhydride, respectively. Polyester and the synthetic resin markets, in turn, are major consumers of these products. meto-Xylene is oxidized on a much smaller scale to produce isophthalic acid, of value in the polyurethane and Nomex aramid (poly(m-phenylene isophthalamide)) technologies. 

Geiger, H., K.H. Becker and P. Wiesen Effect of Gasoline Formulation on the Formation of Hiotosmog A Box Model Study, J. Air Waste Manag. Assoc. 53 (2003) 425 -433. 

Gasoline formulations are typically seasonal. This helps explain the commonly observed increase in gasoline prices in late spring when refineries are changing from winter formulations to summer formulations and demand outpaces supply during the transition. 

Ethers and alcohols are added to gasoline to increase octane and provide an oxygenate in current gasoline formulations. These additives have different properties (molecular weights, vapor pressures, octanol-water partition coefficients), yet are very soluble in water and may be quite mobile in the environment when gasoline spills occur. 

Ethanol is also known as grain alcohol because it can be distilled from grains, such as corn. It is the alcohol that is found in alcoholic beverages, and Ethanol is also added to some gasoline formulations. 

ABSTRACT. This contribution, presented as an introduction to a Panel Discussion of the NATO-Asi meeting, highlights some of the most important subjects concerning gasoline formulation. It is by no means exhaustive, as it is intended to just briefly introduce a few key points of interest such as product quality and its impact on emissions (volatility, oxygenates), additives, need for processing changes and alternative fuels. 

These new constraints on gasoline formulation focused attention on the decreased octane levels of gasoline produced with REY-zeolite cracking catalysts and the octane dip, or low octane number, of C6-C10 paraffins. To compensate, the aromatic content of the gasoline pool was increased from about 20% in 1973 to almost 40%, but the need for new octane catalysts was soon an important objective for refiners and catalyst producers. Octane catalysts require a suitable zeolite that can limit the hydrogen transfer reactions that convert olefins to paraffins. 

Catalytic reforming is a key refinery process. It improves the octane rating of virgin naphthas and light distillates so they can be used in gasoline formulations. The process has also become an important source of aromatics for use in petrochemical production. 

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