Distribution octane number

To evaluate the real behavior of fuels in relation to the segregation effect, the octane numbers of the fuel components can be determined as a function of their distillation intervals In this manner, new characteristics have been defined, the most well-known being the delta R 100 (A7 100) and the Distribution Octane Number (DON). Either term is sometimes called the Front-End Octane Number . 

Another characteristic similar to A/ 100 is the Distribution Octane Number (DON) proposed by Mobil Corporation and described in ASTM 2886. The idea is to measure the heaviest fractions of the fuel at the inlet manifold to the CFR engine. For this method the CFR has a cooled separation chamber placed between the carburetor and the inlet manifold. Some of the less volatile components are separated and collected in the chamber. This procedure is probably the most realistic but less discriminating than that of the AJ 100 likewise, it is now only of historical interest. 

Design Institute for Physical Property Data dimethylformamide dimethylsulfoxide I distribution octane number Economic Commission for Europe j European Economic Community i (Communaute Economique Europeenne)... 

However, in practice the octane number has a ceiling imposed by refining industry constraints such as composition, lead reduction or elimination, cost, and demand volume and distribution. 

In every part of the world, the same type of classification as above is found for fuels premium or regular, with or without lead. The octane numbers can be different from one country to another depending on the extent of development of their car populations and the capabilities of their local refining industries. The elimination of lead is becoming the rule wherever there are large automobile populations and severe anti-pollution requirements. Thus the United States, Japan and Canada no longer distribute leaded fuels. (... 

To the refiner, the question of octane numbers in future gasolines is of primary importance because it determines the course of operations, the development or on the contrary the stagnation of such and such a process. Table 5.12 thus gives an example of the typical composition by origin and concentration of different base constituents of three grades of the most common motor fuels distributed today in Europe conventional premium gasoline at 0.15 g Pb/1, Eurosuper and Superplus. 

When ethanoi is present, the risk of separation is much less than with methanol. Nevertheless, the ethanol should be relatively anhydrous (less than 3000 ppm water) moreover, if a fuel containing ethanol comes in contact with a water layer, a migration of ethanol toward the water is observed creating a fuel quality problem manifested by lower octane number and an environmental quality problem in that the water will need to be treated. Distribution of ethanol-based fuels requires extra precaution to ensure dryness in distribution systems. 

Butylenes. Butylenes are the primary olefin feedstock to alkylation and produce a product high in trimethylpentanes. The research octane number, which is typically in the range of 94—98, depends on isomer distribution, catalyst, and operating conditions. 

Isomerization. Isomerization of any of the butylene isomers to increase supply of another isomer is not practiced commercially. However, their isomerization has been studied extensively because formation and isomerization accompany many refinery processes maximization of 2-butene content maximizes octane number when isobutane is alkylated with butene streams using HF as catalyst and isomerization of high concentrations of 1-butene to 2-butene in mixtures with isobutylene could simplify subsequent separations (22). One plant (Phillips) is now being operated for this latter purpose (23,24). The general topic of isomerization has been covered in detail (25—27). Isomer distribution at thermodynamic equiUbrium in the range 300—1000 Kis summarized in Table 4 (25). 

Acidic isomerization of the C5-C6 naphtha and some heavy alcohols from the aqueous product refinery (not shown in Figure 18.5) produced a reasonable-quality olefinic motor gasoline (Table 18.10). The octane value varied depending on the carbon number distribution of the feed, which could result in a product with an octane number up to ten units higher. 

Effect of Temperature. Figure 5 illustrates the effect of temperature on product distribution. An increase in temperature decreases yields of gasoline and increases gas yields. In addition, the yield of butylenes in the C4 cut increases with increased temperature and the octane number of the gasoline produced is higher,... 

Table V shows that in the Platformate a fairly uniform octane number is attained over the entire boiling range as compared to a decreasing octane number over the boiling range for the thermal reformate. This characteristic of the Platformate is particularly desirable because the octane number of the fuel to the various engine cylinders is relatively uniform regardless of intake manifold distribution effects.

Figure 7 shows calculated octane numbers from hexadecane cracking as a function of gasoline yield. Calcined and steamed zeolites are represented by open and closed symbols, respectively. The calculated octane number reflects changes in the gasoline molecular weight distribution and, to a lesser extent, composition effects. 

In addition to saving acid the additive appeared to improve the octane number by more than 0.1 MDN as was Indicated by a few spot checks of alkylate during the run. The improvements generally arose from a slight Increase In the Cg fraction, a rise In the trimethylpentane concentration and changes of the trl-methylpentane distribution. The octane analyses are not nearly as extensive as the tltratable acidity determinations and the Improvements are noted as being consistent with what would be estimated from plant correlations and the observed reduction In acid composition. 

Different types of polymer degrade into liquid products at different temperature and form hydrocarbons with structural differences according to the structure of the parent polymer. The liquid hydrocarbons obtained by pyrolysis of PE are widely distributed from C3 to C25 and are composed of linear olefins and paraffins. The liquid hydrocarbons obtained from pyrolysis of PP are also distributed in the range C3-C25, but the gasoline fraction obtained in PP pyrolysis has a higher octane number compared with gasoline obtained from PE pyrolysis. 

The foregoing discussion has shown, however, that the molecular structure of the parent alkane profoundly affects the distribution of the intermediate products of its cool-flame oxidation and clearly, there is a strong correlation between the distribution, the degree of branching of the carbon skeleton, the rate of formation of the hydroperoxyalkyl radicals and the Research Octane Number of the alkane. 

This principle may also be illustrated by some real cases. In the codimerization of propene and hexene it is important primarily to minimize the dimerization of the reactive propene. In order to favor the codimerization, a stage injection of propene according to the principle in Fig. 1 was therefore performed [2]. A similar process design with distributed additions of chlorine was applied in the chlorination of propene to allyl chloride in order to suppress different side reactions [3]. For liquid-phase processes, a distributed feed to the cascade of stirred reactors was a more natural variant. This was applied in the sulfuric acid alkylation of / obutane, where the olefin feed has to be subdivided due to selectivity reasons and the goal was to reach a desired octane number of the product [4]. 

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