Octane levels

As of 1 July 1991 all new vehicles registered in Europe should have been adapted for using Eurosuper. However, another quality of unleaded fuel had already appeared in 1988 and has since been well established in some countries, notably France. It is called Superplus, the highest octane level, RON 98, MON 88. Superplus is suitable for vehicles having catalytic converters as well as for a large part of the former automotive fleet requiring an RON of 97 and higher. 

There are many factors to be considered in selecting the type of Powerformer to use. It largely depends on the local situation and includes such things as feed stock, octane level, the value of gasoline yield, the use for by-product hydrogen, plant size, etc. While we can not completely generalize, we can mention some of the more important considerations. 

Process parameters are set to obtain the required octane level ( 90). In the process, minute amounts of carbon are deposited on the catalyst which reduces the product yield, but can be removed by batch burning. Continuous regeneration avoids periodic shutdowns and maximizes the high-octane yield. This employs a moving bed of catalyst particles that is circulated ihrnugli a regenerator vessel, for carbon removal, and returned to the reactor. 

Physical property specifications on products must be considered. In refineries the vapor pressure or octane level of fuel products must satisfy some specification. For blends of various products, you usually assume that a composite property can be calculated through the averaging of pure component physical properties. For N components with physical property values Vt and volume fraction yi9 the average property V is... 

Conventional Fixed-Bed Hydroforming. Pilot plant results on Hastings, California, East Texas, West Texas, and mid-continent heavy naphthas for the fixed-bed process are summarized in Table V the feed stock inspections are presented as Table VI. Yield-octane curves based on these data are on Figure 2, where the wide variation from naphthas of different compositions is apparent. The following tabulation shows the relative yields at two octane levels ... 

When World War II ended, the demand for aviation alkylate dropped, and refiners had excess alkylate which they started using in motor gasoline. About half of the alkylation units were soon shut down, and some of the units were dismantled because the octane levels of motor gasoline were not high enough to justify the continued use of this relatively expensive process (6). 

Reduced Volatility—Volatility reductions would decrease gasoline volume and octane levels and produce excess light hydrocarbons. All gasoline producing facilities would, of course, have to be expanded to make up the volume loss, but greater increases in alkylation and isomerization capacity would be needed to raise octanes and utilize as much of the light hydrocarbons in gasoline as possible. 

At the time this paper was written many questions relating to removal of tetraethyl lead (TEL) from gasolines are still unsettled, but these relate principally to timing, octane levels, etc., and it seems clear... 

Fuels. Catalytic Cracking Catalysts are used lo refined a moderately heavy crude oil fraction known as gas oil to gasoline. The net result of the process is a lighter product with a high content of branched-chain and aromatic hydrocarbons, the species responsible for raising gasoline octane levels. The transformations are complex, hut can be considered lo involve ihe following major acid-catalyzed reactions ... 

Pyrolysis gasoline contains a large quantity of aromatics -typically >60% benzene, toluene and mixed xylene (often referred to as BTX) - which imparts to the fuel a high octane level (typically >95 RON) Table 5.3. Unfortunately, the main component is benzene, which is no longer favoured as a gasoline component which has led to a decline in its use. 

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