Octane severity

Because some hydrocracking occurs, Powerforming also produces saturated C to Q light hydrocarbons. The methane and ethane formed normally are consumed as refinery fuel. Propane and butane products are frequently marketed as LPG. The relative quantities of each of these products vary considerably with feed quality, operating conditions and octane severity. 

Octane response with increase in WAIT at identical pressure and WHSV are shown in Fig.3. An increase of about 12°C in WAIT is needed 10 attain an increase of 7 units in RONC. Fig.4 shows that at 24 kg/cm2 constant pressure and 88 octane severity, an increase of WHSV by 1 in the operational range required WAIT to be increased by 8°C,... 

Similarly to the situation found for Pt(4,6-dFppy)(acac) in /7-octane, several discrete sites are observed in the nonselectively excited emission spectrum of Ir(4,6-dFppy)2(acac) in CH2C12 at 4.2 K (not shown, but compare [50]). However, for the Ir(III) compound the inhomogeneously broadened background is much more intense. In Fig. 7, site-selectively excited emission spectra at different temperatures and a site-selectively detected excitation spectrum are displayed for the region of the electronic 0-0 transitions of the site of lowest energy, denoted as site A. 

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. (... 

Table 5.10 gives octane number examples for some conventional refinery stocks. These are given as orders of magnitude because the properties can vary according to process severity and the specified distillation range. 

Adding lead to a fuel increases octane numbers by several points. From an RON of around 92, the increase is on the order of 2 to 3 points for 0.15 g Pb/1 and of 5 to 6 points for 0.4 g Pb/1. For higher concentrations the effect of saturation appears and additional improvement in the octane number becomes more modest. The preceding values concern the RON as well as the MON. Nevertheless, one more often observes slightly larger increases for the RON. In other words, lead addition tends to increase the sensitivity slightly (on an order of one point for 0.4 g Pb/1). 

In relatively small doses (see Chapter 5), additives made it possible for the refiner to gain several points in octane number and thereby to allow the premium gasoline to meet specifications. 

We cite isomerization of Cs-Ce paraffinic cuts, aliphatic alkylation making isoparaffinic gasoline from C3-C5 olefins and isobutane, and etherification of C4-C5 olefins with the C1-C2 alcohols. This type of refinery can need more hydrogen than is available from naphtha reforming. Flexibility is greatly improved over the simple conventional refinery. Nonetheless some products are not eliminated, for example, the heavy fuel of marginal quality, and the conversion product qualities may not be adequate, even after severe treatment, to meet certain specifications such as the gasoline octane number, diesel cetane number, and allowable levels of certain components. 

Catalyst recovery is a major operational problem because rhodium is a cosdy noble metal and every trace must be recovered for an economic process. Several methods have been patented (44—46). The catalyst is often reactivated by heating in the presence of an alcohol. In another technique, water is added to the homogeneous catalyst solution so that the rhodium compounds precipitate. Another way to separate rhodium involves a two-phase Hquid such as the immiscible mixture of octane or cyclohexane and aliphatic alcohols having 4—8 carbon atoms. In a typical instance, the carbonylation reactor is operated so the desired products and other low boiling materials are flash-distilled. The reacting mixture itself may be boiled, or a sidestream can be distilled, returning the heavy ends to the reactor. In either case, the heavier materials tend to accumulate. A part of these materials is separated, then concentrated to leave only the heaviest residues, and treated with the immiscible Hquid pair. The rhodium precipitates and is taken up in anhydride for recycling. 

The CER engine is operated at two conditions to simulate typical on-road driving conditions. The less severe condition measures research octane number (RON) the more severe one measures motor octane number (MON). Table 1 summarizes the operating conditions for each test. 

These two test methods and the octane numbers of the fuels measured are ultimately used to evaluate the performance of vehicles. The two methods provide usehil information about how fuels perform in cars. The RON corresponds to light load, low speed conditions, whereas the MON corresponds to heavier loads, and high speed severe driving conditions. 

Conditions cited for Rh on alumina hydrogenation of MDA are much less severe, 117 °C and 760 kPA (110 psi) (26). With 550 kPa (80 psi) ammonia partial pressure present ia the hydrogenation of twice-distilled MDA employing 2-propanol solvent at 121°C and 1.3 MPa (190 psi) total pressure, the supported Rh catalyst could be extensively reused (27). Medium pressure (3.9 MPa = 566 psi) and temperature (80°C) hydrogenation usiag iridium yields low trans trans isomer MDCHA (28). Improved selectivity to aUcychc diamine from MDA has been claimed (29) for alumina-supported iridium and rhodium by iatroduciag the tertiary amines l,4-diazabicyclo[2.2.2]octane [280-57-9] and quiaucHdine [100-76-5]. 

The octane number R + M jT) of such reformates is typically in the range of 88.9—94.5, depending on severity of the reforming operation. Toluene itself has a blending octane number of 103—106, which, as shown in Table 19, is exceeded only by oxygenated compounds such as methyl tert-huty ether, ethanol, and methanol. 

There are several versions of the two-step process. One involves the use of 5A molecular sieves in conjunction with Powerforming. In this combination process, the 5A sieves may be used to remove n-paraffms from the feed to improve feed quality. Alternatively, the Powerformate may be sieved to remove the low octane n-paraffm components. Extraction of aromatics from Powerformate is another interesting two-step process. 

ZSM-5 s effectiveness depends on several variables. The cat crackers that process highly paraffinic feedstock and have lower base octane will receive the greatest benefits of using ZSM-5. ZSM-5 will have little effect on improving gasoline octane in units that process naphthenic feedstock or operate at a high conversion level. 

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. 

Gasoline End Point. The effect of gasoline end point on its octane number depends on the feedstock quality and severity of the operation. At low severity, lowering the end point of a paraffinic feedstock may not impact the octane number however, reducing gasoline end point produced from a naphthenic or an aromatic feedstock will lower the octane. 

Benzene. Most of the benzene in the gasoline pool comes from reformate. Reformate, the high-octane blending component from a reformer unit, comprises about 30 vol% of the gasoline pool. Depending on the reformer feedstock and severity, reformate contains 3 vol to 5 voFf benzene. 

Motor Octane Number (MON) is a quantitative measure of a fuel to knocking, simulating the fuel s performance under severe operating condition.s (at 900 rpm and at 300°F). 

The synthesis route just presented will work perfectly well but has little practical value because you can simply buy octane from any of several dozen... 

Tamura etal.2 described only briefly in their paper on dihydropyran derivatives that 6,8-dioxabicyclo[3.2.1]octan-7-one 53 and its methyl derivative underwent polymerization in the presence of a large amount of boron trifluoride etherate to give polymers with molecular weights of several hundreds. 

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