Octane number prediction

FIGURE 12.12 Research octane number predicted from H-NMR vs. RON observed (a) catalyst A (b) catalyst B. 

To predict the octane numbers of more complex mixtures, non-linear models are necessary the behavior of a component i in these mixtures depends on its hydrocarbon environment. 

Kelly, J.J., Barrow, C.H., et. al., "Prediction of Gasoline Octane Numbers from Near-Infrared Spectral Features in the range 660-1215nm", Anal. Chem. 1989(61)313-320. 

Certain rules have been developed for predicting the octane number of different types of gasoline, depending on the ratio of different types of hydrocarbons in the mixtures ... 

In conclusion, pillared clays catalysts are not as good as initially predicted for the cracking of heavy gas oils, mainly because of the iron contamination of natural clays. There is a probability that they could be applied for the conversion of hydrotreated gas oils, giving a slightly lower gasoline yield, but higher octane number than REY zeolites. 

Research Octane Number is a measure of the knocking characteristics of gasoline in a laboratory engine and can be used to characterize gasoline quality. The best linear regression model to predict RON for catalyst A has the form ... 

Correlations presented in the middle thirties enabled the prediction of octane number improvement resulting from thermal reforming (7, 21). They have continued to appear in the literature (6, 20). Improvement of the octane number of naphthas has been the principal function of thermal reforming, but Egloff (8) discusses its usefulness also for the production of light olefins which provide feed stocks for alkylation or polymerization processes. To show the distinct improvement in the yield-octane relationship realized by the catalytic polymerization of C3 and C4 olefins produced by thermal reforming, Mase and Turner (16) present experimental data at various reforming severities for two naphthas. 

Mibashan s (61, 138) relationship was entirely arbitrary. For paraffins, carbon atoms in the longest chain were numbered from the end to the center. A centralization index was developed by adding these position numbers. Corrections were made for various functional groups. Centralization index and octane number were then related by an empirical equation which could be used as a rough prediction guide. 

In Western Europe it is expected that new isomerization capacity may exceed alkylation installations since naphtha availability generally exceeds demand. By selecting isomerization over alkylation the octane number of the gasoline pool may be increased without increasing the volume. Moreover, olefinic charge stock avails for alkylation are considerably smaller in Europe since there are fewer catalytic cracking units per refinery than in the United States and Canada. It is predicted that C5, and to a lesser extent C5/C6 isomerization, will prevail over alkylation in Western Europe until more catalytic cracking units are installed and/or a shift in the demand for naphtha over fuel oil is experienced. 

The octane number of the gasoline fraction composed of the aliphatic polyester fragments could be predicted by taking into account the linear and cyclic oxygenated saturated hydrocarbon nature of the components. 

J. J. Kelly, C. H. Barlow, T. M. Jinguji and J. B. Callis, Prediction of gasoline octane numbers from near-infrared spectral features in the range 660-1215 nm. Anal Chem., 61, 313-320 (1989). 

Research octane numbers for selected alkane fuels and predicted times of ignition [239]... 

A difficult practical problem is the prediction of the octane number of a blend of fuels. As yet, fundamental chemical kinetic modelling has made little contribution to its solution. In general, the octane number of a mixture of fuels is not a linear function of the composition. For example, if two fuels with octane numbers Ni and N2 are mixed in the ratio by volume of fi and (1 - /i) the octane number of the mixture of two fuels, Amix, can be higher or lower than the value given by simple volume weighting, and, in general. 

A.M. Douard and P. Eyzat, Four-Octane-Number Method for Predicting the Anti-Knock Behaviour of Fuels, SAE Technical Paper 780080 (1978). 

From the analysis of the initial data (t—>0), polynomial equations were obtained for the prediction of reformate yield, the temperature needed to obtain a certain octane number (RONC) and hydrogen production in terms of the feed composition, and operating conditions. For example, the theoretical temperature is given by the following equation obtained for Pt-Sn catalysts ... 

From these equations it is posible to predict the temperature required to obtain a certain octane number throughout a cycle. This is shown in Fig. 3 for cycle No. 5. This graph shows the behaviour of the operation temperature and the theoretical temperature for the cycle. 

In many cases analysis by GC involves quite significant peak calibration and identification, only to be followed by extensive peak summing and averaging. Thus, GC is not the technique of choice for such tasks as predicting octane numbers. More often, spectroscopic techniques are correlated through sophisticated statistical treatment known broadly as chemometrics. Applications of near- and mid-IR... 

The Hosoya matrices are used to produce a variety of molecular descriptors, especially since the Z-index and the Hosoya matrix have been extended to polycyclic systems and edge-weighted graphs (e.g., Nikolid et al., 1992 Plavsid et al., 1997 Espeso et al., 2000 Milicevic et al., 2003). Randid (1994a) tested successfully the Z-indices in the structure-boiling point modeling of octanes. Similarly, Hosoya (2002) used his index for predicting the octane numbers of heptanes and octanes. Mathematical properties of the Hosoya Z-indices have also been studied (e.g., Vukicevid and Trinajstid, 2005). 

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