Gasoline octane requirement

Bert, J.A., J.A. Gething, T.J. Hansel, H.K. Newhall, R.J. Peyla and D.A. Voss (1983), A gasoline additive concentrate removes combustion chamber deposits and reduces vehicle octane requirement . SAE paper No. 83-1709, Fuels and Lubricants meeting, San Francisco, CA. 

The model is divided into two parts the calculation of ZSM-5 concentration required to achieve a given activity in the unit (activity maintenance) and the impact of base gasoline composition on the gasoline octane boost for ZSM-5 of a given activity. 

In some circumstances, the octane number of the gasoline used in the engine must be increased to prevent knock caused by accumulated deposits. This phenomenon is called Octane Requirement Increase (ORI). Both prevention and reversal of ORI are difficult to achieve. 

Alkyl lead compounds are extremely effective gasoline antiknock agents. By decomposing to form lead oxide compounds during the gasoline combustion process, lead alkyls interrupt the rapid chain scission reactions which lead to combustion knock. Also, lead alkyls help to prevent exhaust valve seat wear and may minimize octane requirement increase. However, unless utilized in conjunction with lead scavengers such as 1,2-dichloromethane, lead deposits can accumulate within the gasoline combustion chamber. 

Octane Requirements of 1975 Model Year Automobiles Fueled with Unleaded Gasoline", U. S. Environmental Protection Agency, Report 75-28JLB, (August, 1975). Unzelman, G, H., The Oil and Gas Journal, (November 17, 1975), pp. 49-57. 

It is generally accepted that the most suitable zeolites for resid processing as well as maximum octane-barrel applications are of the RE-USY type. The rare-earth exchange/ stabilization is tailored to match the FCC unit s LPG/ Gasoline quality requirements. For the... 

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. 

The octane number of the gasoline product from the TIGAS process will depend on the process layout. Especially the hydrogen level in the loop will influence the octane number (Fig. 12). The highest research octane numbers observed have been a few numbers lower than those obtained in the MTG process (ref. 9), whereas the motor octane numbers are similar. The reduced octane number, which is the result of the low olefinic content in the gasoline, is the penalty to be paid for the benefits obtained by integration. The size of the penalty will depend on the end use of the product from a TIGAS plant, the octane requirements at the specific location and the extent to which octane improvers are available and acceptable. 

Within the next 10 to 15 years lead compounds will disappear as a gasoline octane improver and some 250 million octane tons per year (6 million octane barrels per day) are required to fill this gap. The current estimated average gasoline composition in Western Europe (Ref. 14) is illustrated in Figure 5 below. The two main blending components are reformate and cat cracked gasoline. 

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