Ind. Eng. Chem. Res. 1996, 35, 99-105
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Effect of Reaction Pressure on Octane Number and Reformate and Hydrogen Yields in Catalytic Reforming Kjell Moljord,* Hilde Gunn Hellenes, Anne Hoff, and Ingunn Tanem SINTEF Applied Chemistry, N-7034 Trondheim, Norway
Knut Grande Statoil Research Centre, N-7004 Trondheim, Norway
Anders Holmen Department Industrial Chemistry, NTH, The University of Trondheim, N-7034 Trondheim, Norway
The effect of reaction pressure in catalytic reforming was studied in a pilot reactor with a commercial Pt-Re/Al2O3 reforming catalyst and a hydrotreated naphtha from a North Sea crude. Reformate and hydrogen yields, research octane numbers (RON), and reformate composition at reactor pressures in the range of 12-25 bar were measured as a function of temperature in the range of 95-105 RON. Reformate and hydrogen yields increased as the pressure was reduced. This effect was more pronounced at high severity and in the high-pressure range. For the lower reaction pressures the hydrogen yields increased with increasing severity, but for the higher pressures the hydrogen yields started to decline above certain severities. RON was linearly dependent on the concentration of aromatics in the reformate, although the selectivity toward aromatics depended on both pressure and temperature. Less hydrodealkylation of C8 and heavier aromatics to benzene and toluene resulted in a shift toward xylenes and heavier aromatic components when pressure was lowered. Variations in the degree of paraffin isomerization did not influence RON significantly at those severities. Introduction Catalytic reforming is an important process for conversion of low-octane naphthas into high-octane motor fuels. In a modern refinery catalytic reforming is also an important source of hydrogen for a number of processes. Naphtha consists of a mixture of hydrocarbons having 6-10 carbon atoms, and the low-octane components should be converted to components with better octane rating, mainly aromatics and i-paraffins, in the same boiling range. However, even with modern advanced catalysts those transformations are accompanied by a significant loss of reformate and hydrogen yields, as a portion of the feed is converted to fuel gas (C1 + C2) and LPG (C3 + C4). Recent legislation requires a reduction in emissions of volatile and toxic components in gasoline sold in certain areas in the US. This affects hydrocarbons with high-octane quality, specifically n-butane, light olefins, and aromatics (Unzelman, 1990). As reformate is a major source of aromatics in gasoline, reduced reformer severity can be seen as one way to reduce the amount of aromatics in gasoline. The addition of oxygenates such as methyl tert-butyl ether (MTBE) to gasoline does have beneficial effects on CO emissions (Davis, 1992), and the octane contribution from those additives will allow refiners to reduce reformer severity. The general phaseout of lead in gasoline has led to increased catalytic reformer severity which has been accompanied by a significant loss of reformate yield and cycle length. However, the additional hydrogen generated by increased reformer severity has been utilized * Author to whom correspondence should be addressed. e-mail address:
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to increase the hydrotreating capacity in the refineries. As new legislation on diesel and fuel oil sulfur content is introduced, the demand for hydrogen will increase further. The refineries will thus face a severe problem with hydrogen supply if reformer severity is reduced as a consequence of gasoline reformulation. In order to maintain the hydrogen production when reducing reformer severity, refiners might be considering changes in reformer operating conditions. It is known (Bournonville and Franck, 1988) that both hydrogen and reformate yields increase as the reformer pressure is lowered, but at the expense of increased catalyst deactivation and shorter cycle lengths. With reduced reformer severity there might be room, however, for some reduction of reaction pressure without loss of cycle length. The present work was carried out to examine the effect of reformer pressure on the yields of reformate and hydrogen, as well as on the detailed reformate composition. In particular, emphasis is put on how the reformate composition changes with the reaction conditions, as this kind of information is relevant to gasoline reformulation. The study was carried out in relatively small isothermal reactors without recycle, originally constructed for testing and comparison of different catalysts and feedstocks with respect to catalyst activity, selectivity, and stability. As discussed by Sie and Blauwhoff (1991), this is a type of equipment which will allow discrimination between reforming catalysts and can be used to determine the effect of changes in operating variables as well. Exact predictions of the performance of a commercial reformer unit consisting of 3-4 adiabatic reactors will need additional modeling of the kinetics and the actual reactor configuration. © 1996 American Chemical Society
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Figure 1. Flow diagram for each reactor of the pilot reactor unit (MFC ) mass flow controller; PC ) pressure controller).
Experimental Section Reactor Unit. A schematic flow diagram of the reactor unit is given in Figure 1. The unit consists of three once-through isothermal reactors in parallel, designed for simultaneous testing of different catalysts (or feedstocks). The three reactors are operated independently, which means that a set of three different experimental conditions can be investigated at the same time. The reactors are heated in three separate baths of circulating molten salt, assuring very high rates of heat transfer and good temperature control as reported by Van Trimpont et al. (1988). Each reactor tube has an internal diameter of 19 mm and an available length of approximately 750 mm and is equipped with a central tube for a moveable thermocouple, leaving about 190 cm3 of reactor volume. The catalyst bed was diluted by a low-surface, chloridefree alumina with the same particle shape and size (1/16 in. extrudates) as the catalyst itself. The degree of dilution was varied in three different zones of each reactor, with the highest dilution at the reactor inlet, in order to minimize the temperature drop caused by the rapid, endothermic naphthene dehydrogenation. The temperature drop at the reactor inlet, measured with the axial thermocouple, was less than 5 °C. The reactor effluent was analyzed by on-line GC analysis prior to condensation. Each reactor line was equipped with a HP 5890 GC with a flame ionization detector (FID), interfaced with a PC for data handling and storage. The method of analysis, based on HP’s PONA analysis, included all important hydrocarbons up to C11. Heavier components than this were only present in trace amounts and were not analyzed. Research octane numbers (RON) were calculated from GC analysis based on an adapted version of the method presented by Anderson et al. (1972). The hydrogen yield was calculated from GC analysis as the hydrogen balance over the reactor.
The critical operating variables (temperatures and pressures) were monitored continuously by an in-houseprogrammed PC which would shut the unit down automatically if certain safety limits were exceeded. Test Procedures. The tests were performed with 35 g of catalyst in each reactor, and the catalyst was oxychlorinated, reduced, and sulfided in the reactors prior to testing. Oxychlorination was carried out in order to ensure uniform chloride content as well as a highly dispersed metal function on the catalyst. Oxychlorination was carried out in flowing air with a given ratio of H2O and HCl at 500 °C, before “rejuvenation” of the metal function in dry air. The catalyst was then reduced in H2 at 10 bar, with temperature ramping of +20 °C/h from 400 to 480 °C and kept at 480 °C for 2 h. Finally the catalyst was presulfided with 0.08% H2S in H2 at 425 °C until breakthrough of H2S. After flushing with pure H2, naphtha was introduced at 400 °C, and the reactor temperature was slowly raised to 480 °C. The tests were carried out at WHSV ) 2.03, a molar ratio H2/hydrocarbon ) 4.34, and pressures of 12, 16, 20, and 25 bar. For each pressure level the reaction was examined at three different temperatures, 480, 495, and 510 °C, and each temperature was kept constant for 30-50 h. Prior to this the catalyst was “lined out” at either 16 or 25 bar at 480 °C for about 125 h to stabilize the fresh catalyst. By carrying out a number of repeated runs, the standard deviations for reformate and hydrogen yields were determined as 0.25 and 0.02 wt %, respectively, and 0.25 units for RON. In order to achieve this, a detailed calibration of the GC systems had to be carried out, and the reactor thermocouples, the hydrogen mass flow controllers, and naphtha feed pumps were thoroughly calibrated between each test run. Catalyst and Feed. The tests were carried out with a commercial, balanced Pt-Re (0.3 wt % Pt and 0.3 wt % Re) reforming catalyst, supplied, and used in the form
Ind. Eng. Chem. Res., Vol. 35, No. 1, 1996 101 Table 1. Naphtha Composition (wt %) As Determined by GC Analysis paraffins cyclopentanes cyclohexanes aromatics total C5 C6 C7 C8 C9 C10 C11
0.2 6.3 11.2 14.2 8.0 3.2 0.1
3.2 5.1 6.2 1.2
4.9 8.7 1.5 6.8 0.1
1.4 6.4 8.3 2.7 0.4
0.2 15.8 31.4 30.2 18.7 3.7 0.1
total
43.2
15.7
22.0
19.2
100.1
of 1/16 in. extrudates. A hydrotreated, straight-run naphtha from a North Sea crude was used as feedstock in the test program. The compostion as determined by GC analysis is given in Table 1. The hydrotreated naphtha contained less than 0.5 ppm sulfur. The naphtha was dried over a 4-Å molecular sieve and stored under an inert gas (Ar) prior to use. Using KarlFischer analysis, the water content of dried naphtha was measured to 5-8 wt ppm. In order to compensate the effect of the remaining water on the chloride content of the catalyst, 0.8 wt ppm chloride as 1,1,2-trichloroethane was added to the naphtha. The chloride content of the catalyst at different positions in the reactor was determined after each test run, to check the water/ chloride balance during testing. H2 (99.995%, Norsk Hydro), supplied from gas cylinders, was passed over a deoxo catalyst (BASF R3-11) at 70 °C and a 4-Å molelular sieve to remove traces of oxygen and water. The deoxo catalyst as well as the molecular sieve were regenerated before each test run. Results and Discussion The conversion and selectivity in catalytic reforming are functions of thermodynamic and kinetic factors for the great number of reactions taking place. The desired reactions are the following (Gates et al., 1979): (a) Dehydrocyclization of paraffins into aromatics. (b) Isomerization of alkylcyclopentanes into cyclohexanes. (c) Dehydrogenation of cyclohexanes into aromatics. (d) Isomerization of linear paraffins into isoparaffins. The dehydrocyclization and dehydrogenation reactions are desired also because they produce hydrogen. Both reactions are favored by low reaction pressure and high temperature. The most important side reactions are as follows: (a) Hydrocracking of naphthenes and paraffins. (b) Hydrodealkylation of aromatics. (c) Alkylation and transalkylation of aromatics. (d) Coke formation. Hydrocracking and hydrodealkylation are mostly undesired reactions because they lower the reformate and hydrogen yields, while coke formation deactivates the catalyst and reduces the cycle length, i.e., the time between catalyst regeneration. Indirectly, coke formation also influences the reformate and hydrogen yields because the loss in catalyst activity is normally compensated for by higher reaction temperatures which favor hydrocracking reactions (Little, 1985). Octane Number and Reformate Yield. While the dehydrogenation of cyclohexanes to aromatics is selective and nearly complete, the reactions involving paraffins and alkylcyclopentanes are the most critical ones for obtaining good reformate yield during high-severity reforming (Hughes et al., 1988). High octane numbers
Figure 2. RON as a function of the total concentration of aromatics in the reformate at different reaction conditions (different temperatures and pressures).
can only be achieved through extensive paraffin dehydrocyclization, as the octane number obtained from dehydrogenation of naphthenes and from isomerization of paraffins is well below the desired values (Sterba and Haensel, 1976). Paraffin dehydrocyclization is relatively slow and comparable to paraffin hydrocracking under normal reformer conditions (Sterba and Haensel, 1976). However, under high-severity reforming paraffin dehydrocyclization to aromatics can approach thermodynamic equilibrium values. Furthermore, hydrocracking of paraffins contributes to the high octane numbers by concentrating the aromatics in the reformate. RON depends highly on the concentration of aromatics in the reformate. As shown in Figure 2, there is a linear correlation between RON and the total concentration of aromatics in the reformate, regardless of reaction pressure and temperature. For a given feedstock, variations in the yields of other components (paraffinic or naphthenic) are therefore of minor importance for the research octane number at high-severity reforming. RON is primarily a function of the yield of aromatics and the yield of reformate (C5+), as those two values combined define the concentration of aromatics in the reformate. As RON is so closely linked to the concentration of aromatics in the reformate, changing the operating variables will not influence the content of aromatics in the reformate at a given RON. A simple model for calculation of RON directly from the aromatics concentration has been proposed by McCoy (1975). Based on a linear relationship between the octane number and the concentration of aromatics, RON can be expressed as:
RON ) A × (% aromatics) + B The values obtained by linear regression were A ) 0.4822 and B ) 64.976 with a correlation coefficient r ) 0.9970 over the whole severity range of 95-105 RON. However, it has been demonstrated that this method is not universal, as the coefficients A and B depend on the feedstock (Petroff et al., 1988). Various models based on a linear octane contribution of different components determined by gas chromatography have been proposed (Jenkins et al., 1968; Walsh and Mortimer, 1971; Anderson et al., 1972; Dorbon et al., 1990). RON values calculated from GC analysis by an adapted version of the method presented by Anderson et al. (1972) corresponded to test engine RON values for the debutanized reformate samples (25 samples) with a standard deviation of 0.55 RON units, which is close to the accuracy of the engine measurements.
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Figure 4. Increase in the yield of reformate per bar pressure reduction in the intervals of 20-25 and 12-16 bar.
Figure 3. RON (a) and reformate yield (b) as a function of reaction temperature at different reaction pressures.
In parts a and b of Figure 3, RON and the reformate yield are shown as a function of temperature at 12, 16, 20, and 25 bar pressure. Both RON and reformate yield are favored by low pressure. As a consequence, a lower temperature is needed to obtain a given RON at a lower reaction pressure, and the reformate yield increases as a direct result of low pressure as well as of low temperature. The effect of pressure on reformate yield increases with the temperature, while the effect of pressure on RON is almost temperature-independent. For a given severity in the range of 99-102 RON, the temperature can be lowered by 8-9 °C when going from 25 to 20 bar and by 4-5 °C when going from 16 to 12 bar (Figure 3a). As can be seen from Figure 3b, a temperature reduction of 9.0 °C gives a yield benefit of 2.7 wt % at 20 bar, in addition to a yield increase of 1.5 wt % when reducing the pressure from 25 to 20 bar at constant temperature (498.0 °C, corresponding to 99.0 RON at 25 bar). The yield benefit when reducing the pressure from 16 to 12 bar at a constant temperature (484.3 °C, corresponding to 99.0 RON at 16 bar) is 1.0 wt %, while a temperature reduction of 4.7 °C at 12 bar gives an additional 1.0 wt % yield benefit. At 102 RON the gain in reformate yield by reducing the pressure is even greater than at 99 RON. This is a result of the steeper decline in reformate yield with temperature at high pressure (Figure 3b), so that the difference in yield increases with the severity. The incremental values, calculated as weight percent reformate yield increase per bar reduction in pressure, are given as a function of RON in Figure 4. The benefit in weight percent reformate yield per bar is higher in the high-pressure range than in the lower, regardless of severity. Furthermore, the yield benefit per bar increases substantially with increased severity. Aromatic Components. The aromatics did account for 62-82 wt % of the reformate, depending on the reaction conditions. Toluene was by far the single dominating component, accounting for 23-31 wt % of
the reformate, while benzene accounted for 7-12 wt %. In Figure 5 the yields of the most important aromatics are shown as a function of temperature at pressures between 12 and 25 bar. The yields of benzene and toluene respond to changes in the temperature in a similar way: As expected the yields increase with increasing temperature because dehydrocyclization and dehydrogenation reactions are favoured by high temperature. Furthermore, benzene and toluene formation is favored by lower pressure. On the contrary, the yield of ethylbenzene is reduced with increasing temperature, probably as an effect of more side-chain hydrodealkylation. This reaction is favored by high pressure and gives benzene and ethane as products (Van Broekhoven et al., 1990). The xylenes are less susceptible to high-severity hydrodealkylation than ethylbenzene, and both p- and m-xylene increase with increased temperature for all reaction pressures except at 25 bar, where the yields level off. The yield of o-xylene, however, reaches a maximum at 495 °C and decreases at higher temperatures. p-Xylene differs from the two other xylenes by a much lower pressure dependency. The heavier aromatics, lumped as C9+, diminish with increasing temperature for all the pressures studied but are more pronounced the higher the pressure. The C9+ lump consists of alkylated benzenes, and the strong pressure dependency as with ethylbenzene is probably a result of higher dealkylation tendency for larger alkyl groups on benzene. For C9+ aromatics, this results in a net loss to lighter aromatics such as benzene and toluene with increasing severity. As RON is closely linked to the total concentration of aromatics in the reformate (Figure 2), changing the operating variables will only affect the distribution between the different aromatic components, while the total content of aromatics in the reformate is defined by the RON value. The content of benzene in the reformate is shown as function of RON for different pressures in Figure 6. It is clearly seen that at high severity the benzene content depends on the reaction pressure. At severities above ca. 99 RON the content of benzene increased with increasing pressure as a result of increased benzene (and toluene) formation from heavier aromatics. At 102 RON the content of benzene in the reformate differed by 1.0 wt % (10%) when comparing the results at 12 and 25 bar pressure. At high severity the benzene content of the reformate will therefore be significantly reduced when reformer pressure is lowered. However, at severities below 99 RON the opposite effect was observed. i-Paraffins. Isomerizations of n-paraffins to i-paraffins, and particularly multibranched i-paraffins, are
Ind. Eng. Chem. Res., Vol. 35, No. 1, 1996 103
Figure 5. Yield of different aromatics as a function of reaction temperature at different reaction pressures: (a) benzene, (b) toluene, (c) ethylbenzene, (d) p-xylene, (e) m-xylene, (f) o-xylene, and (g) C9+ aromatics.
desired reactions that contribute to the increase in octane numbers during naphtha reforming. It is common to assume that the isomerization reactions are rapid enough to closely approach thermodynamic equilibrium at normal reforming conditions (Gates et al., 1979). However, the reactivity of the paraffins decreases as their carbon number decreases (Van Trimpont et al., 1988). Furthermore, multibranched isomers are secondary products formed via single-branched isomers (Van Trimpont et al., 1988), and equilibrium is largely attained between normal paraffins and their single-branched isomers (Kmak and Stuckey, 1973). Since the i-paraffins crack much easier than the corre-
sponding n-paraffins, it is not obvious that the i- to n-ratios for all paraffins are defined by their thermodynamic equilibrium at high-severity reforming. As the paraffin isomerization reactions are slightly exothermic, the equilibrium ratio between i- and n-paraffins diminishes slightly with increasing reaction temperature. Furthermore, the isomerization equilibrium is independent of the reaction pressure. Figure 7 shows the experimental i/n-ratios for C4, C5, C6, and C7 paraffins at different pressures and temperatures. The i/n-ratios for C6 and C7 increase from 480 to 495 °C, signifying that chemical equilibrium is not attained between i- and n-paraffins for hexanes and
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Figure 6. Concentration of benzene in the reformate as a function of RON at different reaction pressures.
heptanes at these severities. At higher temperatures (510 °C) the i/n-ratios for C6 and C7 paraffins approach thermodynamic values only at the lowest pressures, 12 and 16 bar. At higher pressures an increase in the temperature above 495 °C results in a net consumption of i-heptanes, exceeding the consumption of n-heptane due to hydrocracking. The same was observed for the hexanes as well, although to a lesser extent. For C6 and C7 paraffins the i/n-ratios at high severity seem to be governed by the consumption of i- and n-paraffins by hydrocracking. The isomerization reactions are obviously not fast enough at those reaction conditions to compete with the hydrocracking reactions, in particular at high pressures. On the contrary, the i/n-ratios of the pentanes diminish with increasing temperature independent of the pressure, as is expected for the isomerization reaction at thermodynamic equilibrium. The measured value at 480 °C (Kexp ) 1.8) corresponds very well with the calculated equilibrium constant (Kth ) 1.89, with data from Stull et al., 1969) but falls more rapidly with increasing temperature than expected. This could be caused by either extensive cracking of i-pentane or formation of n-pentane from cracking. As can be seen from Figure 2, the variations in the degree of paraffin isomerization with the operating conditions did not influence RON significantly. Hydrogen. For a given feedstock the yield of hydrogen is determined by the balance between hydrogenproducing and hydrogen-consuming reactions. Dehydrogenation and dehydrocyclization are the most important hydrogen-producing reactions, while hydrocracking and hydrogenolysis, both undesired reactions which lower the reformate yield, are hydrogen consuming. Figure 8 shows the yield of hydrogen as a function of RON at different pressures. Hydrogen production is favored by low pressures, and more so the higher the severity. At 102 RON, the yield of hydrogen increased by 0.35 wt % (16%) when the pressure was lowered from 16 to 12 bar and by 0.60 wt % (50%) when the pressure was lowered from 25 to 20 bar. The same pressure reductions at 99 RON gave lower hydrogen yield benefits, 0.25 and 0.52 wt %, respectively. At 12 and 16 bar the hydrogen yield increases with increasing severity. At higher pressures the hydrogenconsuming reactions are favored and the hydrogen yields diminish with increasing severity. The severity at which the hydrogen-consuming reactions balance the hydrogen-producing reactions decreases with increasing pressure. At 25 bar the maximum hydrogen yield was attained at a severity below 98 RON, while at 12 bar the maximum hydrogen yield was above 104 RON. The
Figure 7. i/n-ratios for different paraffins as a function of reaction temperature at different reaction pressures: (a) butanes, (b) pentanes, (c) hexanes, and (d) heptanes.
effect of severity on hydrogen yields therefore depends on the operating conditions: At reformer pressures below 16 bar the hydrogen yields decrease when the severity is reduced, while at higher pressures the hydrogen yields may even increase when lowering the severity. Conclusions The study shows that a reduction of the reaction pressure results in higher reformate and hydrogen yields. This effect is more pronounced at high-severity operation and in the high-pressure range. Maximum
Ind. Eng. Chem. Res., Vol. 35, No. 1, 1996 105
Figure 8. Yield of hydrogen as a function of RON at different reaction pressures.
hydrogen yields were observed at lower severity the higher the pressure. A linear correlation between RON and the content of aromatics in the reformate was found: Independent of the reaction conditions, a given concentration of aromatics in the reformate is needed to achieve a certain RON value. However, the relative amount of the different aromatic components depends on the operating conditions. Less hydrodealkylation to benzene and toluene results in a shift toward xylenes and heavier aromatics at lower reaction pressure. Therefore, the benzene content of the reformate decreases when the pressure is lowered at high-severity operation. Variations in the degree of paraffin isomerization as a result of changing reaction conditions did not influence RON significantly at those severities. The i/n-ratios of C6 and C7 paraffins approach chemical equilibrium values only at low reaction pressures and high severity. At low severity chemical equilibrium apparently was not reached for those isomerization reactions, while at high pressure and high severity the branched isomers were hydrocracked to give lower than equilibrium i- to n-ratios. Acknowledgment
Bournonville, J. P.; Franck, J. P. Hydrogen and Catalytic Reforming. In Hydrogen Effects in Catalysis. Fundamentals and Practical Applications; Paa´l, Z., Menon, P. G., Eds.; Marcel Dekker, Inc.: New York, 1988; Vol. 31, p 653. Davis, B. C. Adventures in Clean Air Act Amendments Implementation. Hydrocarbon Process. 1992, 71 (5), 91. Dorbon, M.; Durand, J. P.; Boscher, Y. On-line Octane-number Analyser for Reforming Unit Effluents. Principle of the Analyser and Test of Prototype. Anal. Chim. Acta 1990, 238, 149. Gates, B. C.; Katzer, J. R.; Schuit, G. C. A. Chemistry of Catalytic Processes; McGraw-Hill Book Co.: New York, 1979; p 184. Hughes, T. R.; Jacobson, R. L.; Tamm, P. W. Catalytic Processes for Octane Enhancement by Increasing the Aromatics Content in Gasoline. In Catalysis 1987; Ward, J. W., Ed.; Elsevier: Amsterdam, The Netherlands, 1988, p 317. Jenkins, G. I.; McTaggart, N. G.; Watkin, B. L. H. GLC for OnStream Octane Number Rating of Stabilized Catalytic Reformates. In Gas Chromatography 1968; Harbourn, C. L. A., Ed.; Institute of Petroleum, London, 1968, p 185. Kmak, W. S.; Stuckey A. N., Jr. Powerforming Process Studies with a Kinetic Simulation Model. (Paper No. 56a). AIChE National Meeting, New Orleans, March 14, 1973. Little, D. M. Catalytic Reforming; Penn Well Publishing Co.: Tulsa, OK, 1985; p 55. McCoy, R. D. Catalytic Reformer Product Octane Measurement via Total Aromatics. ISA Trans. 1975, 14, 161. Petroff, N.; Boscher, Y.; Durand, J. P. Determination automatique de l'indice d’octane et de la composition des reformats par chromatographie en phase gazeuse. Rev. Inst. Fr. Pet. 1988, 43 (2), 259. Sie, S. T.; Blauwhoff, P. M. M. Laboratory Equipment and Procedures for Evaluation of Catalysts in Catalytic Reforming. Catal. Today 1991, 11, 103. Sterba, M. J.; Haensel, V. Catalytic Reforming. Ind. Eng. Chem., Prod. Res. Dev. 1976, 15 (1), 2. Stull, D. R.; Westrum, E. F.; Sinke, G. C. The Chemical Thermodynamics of Organic Compounds; John Wiley & Sons, Inc.: New York, 1969. Unzelman, G. H. Reformulated Gasolines will Challenge Product Quality Maintenance. Oil & Gas J. 1990, 88 (15), 43. Van Broekhoven, E. H.; Bahlen, F.; Hallie, H. The Reduction of Benzene in Reformate. AIChE Spring Meeting, Orlando, FL, March 18-20, 1990. Van Trimpont, P. A.; Marin, G. B.; Froment, G. F. Reforming of C7 Hydrocarbons on a Sulfided Commercial Pt/Al2O3 Catalyst. Ind. Eng. Chem. Res. 1988, 27, 51. Walsh, R. P.; Mortimer, J. V. New Way to Test Product Quality. Hydrocarbon Process. 1971, 50 (2), 153.
The authors are grateful to Statoil for supporting this work and for the permission to publish the results.
Received for review October 6, 1994 Revised manuscript received May 19, 1995 Accepted September 12, 1995X
Literature Cited Anderson, P. C.; Sharkey, J. M.; Walsh, R. P. Calculation of the Research Octane Number of Motor Gasolines from Gas Chromatographic Data and a New Approach to Motor Gasoline Quality Control. J. Inst. Pet. 1972, 58 (560), 83.
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Abstract published in Advance ACS Abstracts, November 15, 1995. X
