Motor fuels performance

The composition of motor fuels is undergoing constant change in view of improving performance while protecting the environment. 

CEC Coordinating European Council for the Development of Performance Tests for Lubricating Oils and Motor Fuels i... 

Lead is an element used in many industrial processes and also has been used in fuels and coatings. Tetraethyl lead was added to gasoline to improve performance as a motor fuel, and elemental lead was extensively used in paints and coatings to improve coverage and durability until the 1970s, when phase-out efforts began to reduce lead emissions to the environment. 

Wiese Formula An empirical formula developed by General Motors Research for expressing motor fuel antiknock values above 100. This value is obtained by measuring the number of milliliters of tetraethyl lead added per gallon to achieve the same knocking tendency as the fuel being tested. The determined value is then expressed as a performance number. 

Figure 8. Road Octane Performance of Motor Fuels...

The foregoing pages have shown a number of ways in which physical constants vary with molecular structure. Petroleum chemists and automotive engineers have come to recognize that the performance of a motor fuel in an internal combustion engine is also dependent upon the structure of the hydrocarbon molecules which the fuel contains. This does not mean that engine performance is a function of the physical constants, but rather that the features of molecular structure which determine the one also determine the other. 

Organic sulphur- and nitrogen-compounds in motor fuels are a source for acid rain and harmful to the environment. Moreover, they are poisonous to the auto exhaust catalysts. To meet new developments in EU regulations on the S-concentration, a commonly applied one-step hydrodesulfurization (HDS), using conventional catalysts, e.g. C0-M0/7-AI2O3, is insufficient. A second HDS step, viz. a deep HDS step, can be more economical to reduce the S-content to the currently allowed European level of 350 ppm. This level will be reduced further to 50 ppm in 2005 [1]. In the first HDS step, often the heavy organic sulfur-containing polyaromatics survived, such as dibenzothiophene (DBT) and (4-, and/or 6-) alkylated DBTs [2,3]. They are the most refractory. In crude oils, there are also aromatic N-compounds, which suppress the performance of the HDS catalysts. Hence, a model feed for representative HDS-activity measurements should contain characteristic S- and N- compounds for practical relevance. 

Sometimes the inspection tests attempt to measure these properties, for example, the carbon residue of a feedstock that is an approximation of the amount of the thermal coke that will be formed during refining or a research octane number test devised to measure performance of motor fuel. In other cases the behavior must be determined indirectly from a series of test results. 

Motor fuels are an important product. Gasoline is required for spark-ignition engines. The different needs of aircraft and vehicles are constrained by the different qualities of the fuels produced in the refineries. Aviation fuels demand a high octane. Other products are added to motor fuels to improve their performance in automobiles. 

MAJOR USES Manufacture of diphthalic anhydride, phthalic anhydride, phthalonitrile, benzoic acid, ethyl benzene, high performance polymers, plasitcizers, alkyd resins, glass reinforced polyesters, dyes, insecticides and motor fuels. 

Uses Motor fuel std. reference fuel for octane ratings petrol, blending component reagent in spectrophotometric analysis org. synthesis solvent thinner environmental analysis (e.g., pesticide residues) high performance liq. chromatography gas chromatography UV and IR spectroscopy solvent, film-former for cosmetics, personal care Regulatory HAP... 

Carbon-Carbon Bond Formation. Various types of Bronsted and Lewis acids and superacids may be applied to perform the reaction of alkanes or arenes with different alkylating agents (alkenes, alkynes, alkyl halides, alcohols, ethers, esters). Acid-catalyzed alkylations, particularly alkane-alkene reactions, are of great practical importance in upgrading motor fuels. Acid-catalyzed alkylation produces alkylaromatics for manufacture of plastics (styrenes), detergents, and chemicals. 

It is recognized that the value of industrial products is determined more than before by their performance, which cannot always be expressed in terms of their composition. Well known examples of this include products such as motor fuels, lubricants, plastics, fibres, paints, lacquers, adhesives, agricultural chemicals, pharmaceutical products, and photographical chemicals, that is to say almost all chemical end products. These are to distinguished from intermediate chemical products, often called chemicals, the quality of the latter can usually be specified in terms of their composition. The manufacturing industries that convert the chemical end products into consumer products are often faced with strict quality requirements and sometimes even with product liabilities. They are therefore likely to put stringent requirements on the performance of the raw materials, that are the end products of the chemical industry. In such situations both suppliers and purchasers often prefer to make long term contracts that specify, both sales volumes and product performance. For the chemical industry this means that products of very specific properties have to be made and that these properties have to be constant in time. This requires very careful production control, and consequently a very accurate control of the performance of chemical reactors. 

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