Octane number factors affecting

The amount of water solubilized in a reverse micelle solution is commonly referred to as W, the molar ratio of water to surfactant, and this is also a good qualitative indicator of micelle size. This is an extremely important parameter since it will determine the number of surfactant molecules per micelle and is the main factor affecting micelle size. For an (AOT)/iso-octane/H20 system, the maximum Wq is around 60 [16], and above this value the transparent reverse micelle solution becomes a turbid emulsion, and phase separation may occur. The effect of salt type and concentration on water solubilization is important. Cations with a smaller hydration size, but the same ionic charge, result in less solubilization than cations with a large hydration size [17,18]. Micelle size depends on the salt type and concentration, solvent, surfactant type and concentration, and also temperature. 

Typical reforming catalyst are bifunctional, with a metal function (Pt, Pt-Re, Pt-Ir, etc] and an acid function (chlorided alumina). During operation, along with the desired reactions, the deposition of carbonaceous material occurs over the metal and the acid sites (1). This coke is the most important factor affecting the lifetime of the catalyst. As a consequence of this deposition, the reactor temperature must be raised to maintain the same octane number In the reformate. The partially deactivated catalyst has different selectivity than the fresh one. This suggests that the coke is deposited to a different extent on the metallic and on the acid function, and that the more demanding reactions are preferentially deactivated (2). 

A number of other reactions have been demonstrated in which an oxidative transformation occurs at an interface, but the factors affecting the rates have not been examined [2]. Some progress in this direction was made in a simple redox reaction between hydro-phobic porphyrin dissolved in octane and a hydrophilic donor - sodium dithionite dissolved in water [43]. 

The octane number (Motor method) of straight-run gasolines is related to Characterization Factor somewhat as indicated in Table 4-15, but note particularly the wide variation in octane number. Boiling range and particularly the cut point also affect the octane niunber (see Tables 4-16 and 4-17). Each gasoline differs in its behavior, but the general... 

Schwarzenbek et al., Factors Affecting Octane Number, Proc. Third World Pet. Congr., sec. IV, The Hague, 1951. 

The octane number of the gasoline is affected by the reactor temperature (Table 21-5) but scarcely at all by other operating conditions. It increases only 0.5 to 1.0 units (sometimes none) for an increase in the conversion of 10 per cent (in the range of 50 to 80 per cent) and it increases only slightly with catalyst-to-oil ratio. However, low Characterization Factor feeds produce gasolines of slightly higher (1 to 3 units) octane numbers, and Table 21-5 is based primarily on Mid Continent feeds such... 

In the same group, the oxide of tungsten was observed to be a selective dehydration catalyst, irrespective of hydrogen or air pretreatment.Nevertheless, the octene distribution from octan-2-ol was affected by the pretreatment and as O " ions were removed, fra s-oct-2-ene became favoured and geometric factors are probably of importance. It was suggested that high cisitrans ratios may occur either when basic oxygen sites crowd closely around the catalytic site or when the metal ion has a lower co-ordination number. 

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