Research and motor octane numbers

The original CFR test conditions appear in the second column of Table 7.2. These constitute the Research method and assign the fuel a Research octane number (RON). It was found that typical fuel susceptibility to knock in practical engines did not correlate sufficiently well with this test and one with rather more severe conditions - the Motor method, giving the Motor octane number (MON) - now also is used. These conditions are given in the third column. The inlet manifold temperature and speed have been increased, spark timing advanced, and a shrouded inlet valve fitted to 

Spark timing, crank angle before tdc 13 14 to 26° (depends on CR) 

The difference between the RON and MON values for a fuel is called the sensitivity. The sensitivity for most practical paraffinic (e.g., alkylate) fuels is close to zero (and exactly so, by definition, for n-heptane and isooctane), but Fig. 7.2 shows that some low octane number alkanes have values of MON RON. However, in the practical range of ON ( 70) for aromatics and especially alkenes, the MON is usually less than the RON. For commercial gasolines the sensitivity is about 10 octane numbers, depending on the aromatic and alkene content. Although the RON of fuels is more usually quoted and is determined in the CFR test more 

It is worth re-emphasizing that the end gas temperature and pressure in the octane number tests depend on the fuel. High octane fuels are necessarily tested with higher compression ratios, with correspondingly higher compressed gas temperatures and pressures, than low octane fuels. From 

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Table 12.2 Research and motor octane numbers (RON, MON) of C5-C7 alkane isomers.

World-Wide there is approximately 1000 tons of fluid cracking catalyst manufactured each day. Of this, about 35% contains some form of aluminum deficient zeolite Y, one whose SiOz/AlaOa ratio exceeds 5.5 1, and whose performance is generally characterized by enhanced olefin formation and higher gasoline research and motor octane number. The aluminum deficient... 

Figure 4. Research and motor octane numbers (clear) for equilibrium conversions for C5 and C6 isomerization. Motor octane number curves estimated from data presented by Erickson et al. (24). Basic information contained in Figure 3...

Research and motor octane numbers are calculated for the gasoline fraction using a GC-based compositional octane model. 

Fig.2 shows the lead response, i.e. the increase in Research and Motor Octane Numbers, obtained when different concentrations of either TEL or TLM are added to various typical gasoline components. 

Fig. 14 Hydrogenolysis on metal catalysts product from ring opening reactions of Cl ring contraction compounds and their corresponding research octane number and motor octane number. Adapted from ref. 100.

TABLE 3-3. Research Octane Number and Motor Octane Number Test Parameters... 

The significance of the equilibrium relationships become more apparent to the refiner when the unleaded research and motor octane values for each carbon group are volumetrically blended and plotted vs. temperature. Such a curve is shown in Figure 4. The sensitivity for the C5 and C6 paraffins is about 1-2 numbers on a clear basis vs. 10-13 for the C6 naphthenes. All of the octane numbers for these components are shown in Table IV. 

RO and MO are research octane number and motor octane number, respectively. 

Measure of the ability of gasoline to resist knocking when ignited in a mixture with air in the cylinder of an internal-combustion engine. There are Research Octane Number (RON) and Motor Octane Number (MON). RON is usually 10 points higher than MON for the same gasoline. 

The term refinery alkylation is applied to the reaction of low molecular weight olefins (propene, butenes, or pentenes) with isoparaffins to form higher molecular weight isoparaffins. The latter are very important hydrocarbon compounds for the production of high-quality fuel (Scheme 6.10.1). Currently, approximately 13-15% of the gasoline pool is produced by refinery alkylation. Refinery alkylation products are characterized by high research octane numbers (RONs) (93-97) and motor octane numbers (MONs) (90-95). 

One of the advantages of GC-MS over an IR spectroscopic analyzer is the ability to measure distillation characteristics as well as predict other properties. There are several other materials that can be directly measured and reported. These include benzene, total aromatics, oxygenates, certain sulfur compounds and additives. The properties that can be predicted include (among others) cetane number and index, research and motor octanes, refractive index, distillation properties, aniline point, cloud point, pour point, volatility, flash point, density, conductivity, and viscosity [57]. 

There are two standard procedures for determining the octane numbers Research or FI and the Motor or F2 methods. The corresponding numbers are designated as RON (Research Octane Number) and MON (Motor Octane Number) which have become the international standard. 

Saturation of olefins other than reactive olefins usually is not desired. The added hydrogen is often expensive or useful elsewhere, and it does not provide any real improvement in product quality. Acmally, product quality may be reduced in the case of gasolines. Research octane number losses may be correlated with increasing olefin saturation. So in many cases, hydrodesulfurization conditions are selected with an eye toward minimizing olefin saturation over and above that needed for product quality improvement. There is one exception saturation of certain olefins shows substantial improvements in Motor octane number. This is true for iso- and n-pentenes and to a lesser extent for higher boiling isoolefins. The higher n-olefins show octane losses upon saturation. 

Volume of olefin/(volume of ionic liquid.hour). i-C = 2,2- and 2,3-dimethylbutanes, i-Cg = isooctanes, TMP trimethylpentanes, = hydrocarbon products with more than eight carbon atoms, Light ends = hydrocarbon products with fewer than eight carbon atoms, RON = research octane number, MON = motor octane number... 

Two octane numbers are routinely used to simulate engine performance the research octane number (RON) simulates gasoline performance under low severity ( 600 rpm and 120°F (49°C) air temperature), whereas the motor octane number (MON) reflects more severe conditions ( 900 rpm and 300°F (149°C) air temperature). At the pump, road octane, which is the average of RON and MON, is reported. 

Fig. 13 Possible products from methylcyclohexane and their research octane number (RON) and their motor octane number (MON). Adapted from ref. 100.

Now there are two octane scales, a research octane number (RON) and a motor octane number (MON). RON values reflect performance at 600 rpm, 125°F, and low speed. MON is a performance index of driving with 900 rpm, 300°F, and high speed. Before 1973 RON values were the ones usually... 

FCC Gasoline. The produced light FCC gasoline typically contains a mixture of paraffins, olefins, and aromatic compounds in a ratio of around 5 3 2. This ratio will often vary depending upon feedstock, catalyst quality, and reactor parameters. The research octane number of FCC gasoline will typically be much higher than the motor octane number. 

Engine knock is measured by two ASTM methods, ASTM D-2699 and D-2700. Method ASTM D-2699 is identified as the research octane number (RON) and method ASTM D-2700 is identified as the motor octane number (MON). The primary differences between these two methods are summarized in TABLE 3-3. 

Both motor octane number (MON) and research octane number (RON) values of finished fuel blends are measured using the whole fuel, not individual fuel fractions. However, the octane number contribution of the various fuel fractions can influence the overall knock resistance. Finished fuels with identical RON values may contain fractions with either very similar or widely different octane number values. 

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