Gasoline octane quality

Table VIII. Automobile Compression Ratio and Gasoline Octane Quality...

Bioethanol is also a very attractive compound for increasing gasoline octane quality and it can be added up to 10% to gasoline (E5 is the preferred European solution while ElO is used in USA) without engine modification or also used practically pure, as E85 or ElOO, in the Flexible Fuels Vehicles. 

The trend in d and has also been accompanied by improvements in product quality illustratisd by the increases in gasoline octane numbers and diesel oil cetane numbers. 

We cite isomerization of Cs-Ce paraffinic cuts, aliphatic alkylation making isoparaffinic gasoline from C3-C5 olefins and isobutane, and etherification of C4-C5 olefins with the C1-C2 alcohols. This type of refinery can need more hydrogen than is available from naphtha reforming. Flexibility is greatly improved over the simple conventional refinery. Nonetheless some products are not eliminated, for example, the heavy fuel of marginal quality, and the conversion product qualities may not be adequate, even after severe treatment, to meet certain specifications such as the gasoline octane number, diesel cetane number, and allowable levels of certain components. 

Finally, the product slate (e.g. olefin production, petrochemical feedstock production), or the product quality (e.g. gasoline octane improvement) may dictate a reduction in rare earth usage. 

Compositions of lead free gasoline with octane qualities equivalent to present day gasoline are shown in Table IV. These compositions represent the sum total of the many different refinery models presented in the API report. 

The most important quality parameter for gasoline is the octane quality. 

Octane number is the important property in gasoline. Octane number measures the resistance offered by the fuel to compression. A higher octane implies higher resistance to compression (to promote high antiknock quality, ease of starting, quick warm-up, low tendency... 

Fig. 7.3. Development of Research Octane Number of two grades of gasoline in Germany, with the technologies responsible for the changes. The octane quality of the original unprocessed hydrocarbon (S.R. tops) was improved and augmented by material from cracking and reforming processes, from tetra-alkyl lead addition and by alcohols which were used at times of crisis because they could be produced from internal resources.

Another important issue of ethanol is its water sensitivity, which affects the water tolerance of gasoline in the case ofwater presence in ethanol-added gasoline, there is, in fact, the formation of hydrogen bonds between water and alcohol and the blend separates into two phases, with loss of octane quality. As a consequence, bioethanol requires special handling with different storage and distribution facilities for alcohol and gasoline and the blend has to be carried out just before the final use. 

Antiknock Compounds—improve octane quality of gasoline... 

These processes also largely fall into the category of hydrocarbon conversion or conversion of nonhydrocarbons to hydrocarbons over acid catalysts. They include the reactions of olefins, paraffins, aromatics and their mixtures in the production of high octane gasoline, high quality diesel, jet fuel, distillate fuels and lubricants. Table 1 shows a partial list of these processes. 

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