Ind. Eng. Chem. Process Des. Dev. 1986, 25,
gram. Shale oil was provided by Southern Pacific Petroleum N.L. We gratefully acknowledge the assistance of R. J. Western with the GC-MS analyses. Registry No. Ni, 7440-02-0; W, 7440-33-7;Co, 7440-48-4;Mo,
527-528
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Harvey, T. G.; Matheson, T. W.; Pratt, K. C. Anal. Chem. 1984, 5 6 , 1277. Harvey, T. G.; Matheson, T. W.; Pratt, K. C.: Stanborough, M. S. Fuel 1985, 64,925. Holmes, S. A.; Thompson, L. F. Fuel 1983. 62, 709. Kan, K. M. Ampol Petroleum, private communication, 1983. Katzer, J. R.; Sivasubramanian, R. Catal. Rev. Sci. Eng. 1979, 20, 155. Kirk-Othmer, Ed. "Encyclopedia of Chemical Technology", 3rd ed.; Wiley-Interscience: New York, 1981; Vol. 16, p 333. Montgomery, D. P. Ind. Eng. Chem. Prod'. Res. Dev. 1968, 7 (4), 274. National Energy Advisory Committee, Report 12, Australian Government Publishing Service, Canberra, 1960. Proskuryakov, V. A.; Yakovlev, V. I. CHEMRAWN 1 , Toronto, 1978. Regtop, R. A.; Crisp, P. T.; Eiiis, J. Fuel 1982, 61, 185. Shue, F.-F.; Yen, T. F. Anal. Chem. 1981, 53, 2081. Solash, J.; Hazlett, R. N.; Burnett, J. C.; Beal, E.; Hall, J. Prepr.-Div. Fuel Chem., Am. Chem. SOC. 1980, 25(3), 22. Tait, A. M.; Newitt, T. D.; Hensley, A. L. European Patent Appl. 0050 911 A I , 1981. Tait, A. M.; Hensley, A. L. frepr.--Div. FuelChem., Am. Chem. SOC.1982, 27(2), 187. Thakkar, V. P.; Baldwin, R. M.; Bain, R. L. Fuelfroc. Techno/. 1981, 4 , 235. Tissot, B. P.; W e b , D. H. "Petroleum Formation and Occurrence"; Springer Verlag: Berlin, 1978. Uden, P. C.; Carpenter, A. P.; Hackett, H. M.; Henderson, D. E.: Siggia, S . Anal. Chem. 1979, 51 38. Van Meter, R. A.; Bailey, C. W.; Smith, J. R.; Moore, R. T.; Albright, C. S . ; Jacobson, I.A.; Hylton, V. M.; Ball, J. S . Anal. Chem. 1952, 2 4 , 1758. Weisser, 0.;Landa, S. "Sulphide Catalysts, Their Properties and Applications"; Pergamon Press: Oxford, 1973.
1439-98-1.
Literature Cited Ahuja, S. P.; Derrien, M. L.; Le Page, J. F. Ind. Eng. Chem. Process Des. Dev. 1970, 9 . 272. Benson, D. B.; Berg, L. Chem. Eng. frog. 1986, 62(8), 61. Ben, G.: Harvey, T. G.; Matheson, T. W.; Pratt. K. C. Fuel 1983, 62, 1445. Carpenter, H. C.; Cottingham, P. L. Rep. Invest.-U. S. Bur. Mines 1959, 5533. Central Pacific Minerals, Sydney, Australia, Annual Report, 1980. Crowley, R. J.; Siggia, S . : Uden, P. C. Anal. Chem. 1980, 52, 1224. Curtain, D. J.: Dearth, J. D.: Everett, G. L.; Grosboll, M. P.; Myers, G. A. frepr.-Div. Fuel Chem., Am. Chem. SOC. 1978, 23 (4), 18. Dineen, G. U.; Bickel, W. D. Ind. Eng. Chem. 1951, 43 1604. Drushei, H. V.; Sommers, A. L. Anal. Chem. 1988, 38, 19. Ford, C. D.; Holmes, S. A,; Thompson, L. F.; Latham, D. R. Anal. Chem. 1981, 53, 831. Frankenfeld, J. W.; Taylor. W. F.; Brinkman, D. W. Ind. Eng. Chem. Prod. Res. Dev. 1983, 22, 622. Frost, C. M.; Jensen, H. B frepr.-Div. Petrol. Chem., Am. Chem. SOC. 1973, 18,119. Frost, C. M.: Cottingham, P. L. Rep. Invest.-U. S. Bur. Mines 1973, 7738. Frost. C. M.; Poulsen, R. E.; Jensen, H. B. US Energy Research and Development Administration Report, LERC/RI 7513, Washington, DC, 1975. Frost, C. M., Poulsen, R. E.: Jensen, H. B. Adv. Chem. Ser. 1978, No. 15 77. Hardy, D.; Hazlett, R. N.; Solash, J. Prepr.-Div. Fuel. Chem., Am. Chem. SOC. 1982. 2, 201.
Received f o r review November 28, 1984 Revised manuscript received August 26, 1985 Accepted September 19, 1985
Aberrant Behavior of Certain Multicomponent Activity Coefficient Equations when Applied to Isomer-like Components Leon S. Scott, Noel G. O'Brien,' and 01 Muthu E. I. do font de Nemours & Company, Inc., Wilmington, Delaware 19898
I t has been found that certain equations for activity coefficients in multicomponent systems give erroneous results under certain conditions. For example, two isomers that form an ideal mixture and have identical vapor pressures and identical binary activity coefficients, in a solvent, must have identical ternary activity coefficients in that solvent. I f this were not so, the two identical isomers could be separated in an extractive distillation column by using that solvent. However, two classical multicomponent activity coefficient equations imply that the two identical isomers could go in different directions in the column.
The Wohl 3-suffix equation (Wohl 1946, 1953), as described by Oliver (1966) in the case where no experimental ternary constant is employed, fails to meet the equal activity coefficient requirement. The very simple, but very useful, Kohler (Schotte, 1980) equation also fails the test as demonstrated by the numerical example given in Table 11. The terminal activity coefficients for the hypothetical computational test mixture used to evaluate Table I1 are given in Table I. Table I states that components 1 and 3 have identical terminal activity coefficients in solvent 2 and components 1 and 3 form ideal mixtures with each other. Examination of Table I1 shows that the isomer-like components 1 and 3 have very different activity coefficients when the Wohl 3-suffii Margules or the Kohler equation is employed. The Renon (NRTL) (Renon and Prausnitz, 1968), Chien-Null (1972), Wilson (1964), and Uniquac (Anderson and Prausnitz 1978), however, correctly give identical activity *Present address: P.O. Box 304, Newark, DE 19715. 0196-4305/86/1125-0527$01.50/0
Table I. Terminal Activity Coefficients Used in the Numerical Examplea component i
component j
TI/;
2 3 1 3 1 2
3.10 1.00 1.30 1.30 1.00 3.10
Components 1 and 3 are assumed to be identical isomers.
coefficients for components 1and 3. The same conclusions are reached for a four-component system using two isomer-like components in a mixed solvent. A numerical example of a four-component test case is given in the supplementary material described at the end of the paper. If, however, the isomers are either very dilute or of equal concentration, the calculated activity coefficients using the multicomponent Margules or Kohler equations will be found to be identical within a given case as they should be. 0 1986 American
Chemical Society
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Ind. Eng. Chem. Process Des. Dev.
Table 11. Comparison of Various Equations when the Ratio of the Isomer Concentrations Is Infinite component no. 1 2 3 test composition (mole fraction) 0 0.6 0.4
Test Equations Kohler (van Laar bin.)” 1.7543 Kohler (Margules bin.) 1.6335 1.4414 Quaternary Margules (Wohl) Renon (NRTL) 1.0921 Chien-Null (van Laar bin.) 1.0783 Wilson Uniquac a
1.0810 1.0820
1.1554 1.0783 1.2322
1.1700
1.2322 1.1700 1.1918 1.0921 1.1554
1.0783
1.1595 1.0810 1.1763
1.0820
bin. = binary.
If the isomer-like components are lumped into a single pseudocomponent, the defective equations can still be utilized. A person wishing to use a multicomponent activity coefficient equation can simply use the test case given here to determine if the equation satisfies the equal activity coefficient criterion described above.
1966,25, 528-531
Acknowledgment We thank W. Schotte for his assistance in making some of the computations. Literature Cited Anderson, T. F.;Prausnitz, J. M. Ind. Eng. Chem. Process Des. Dev. 1978. 17, 553. Chien, H. Y.; Null, H. R. AIChE J . 1972, 78, 1177. Oliver, E. D. “Diffusional Separation Processes”; Wiley: New York, 1966; p 41. Rehon, H.; Prausnitz, J. M. AIChE J . 1968, 14, 135. Schone, W. Ind. Eng. Chem. Process Des. Dev. 1980, 19, 432. Wilson, G. M. J. Am. Chem. SOC. 1964, 8 6 , 127. Wohl, K. Trans. Am. Inst. Chem. Eng. 1946, 4 2 , 215. Wohl. K. Chem. Eng. Prog. 1953, 49 (4), 218.
Received for review February 19, 1985 Revised manuscript received July 25, 1985 Accepted September 26, 1985 Supplementary Material Available: Numerical example of a four-component test case (1page). Ordering information
is given on any current masthead page.
Suppression of Sulfur Trioxide Formation in a Monolithic Catalytic Converter for Cars due to Oscillating Reaction Conditions Per Olsson and Nlls-Herman Schoon’ Department of Chemical Reaction Engineering, Chalmers University of Technology, Gothenburg, Sweden
The net formation of sulfur trioxide in the presence of an excess of carbon monoxide with respect to sulfur dioxide was studied under different reaction conditions in a single element of a commercial monolithic Pt, Rh converter. Conditions giving rise to self-oscillations were found to result in a complete oxidation of carbon monoxide and in only a 10% net conversion of sulfur dioxide.
It is well-known that sulfur compounds in gasoline are completely oxidized to sulfur trioxide, sulfuric acid, and sulfates in the catalytic converter of the car. Noncatalytic automobile systems emit only insignificant amounts of these compounds. Despite the fact that the cleaned exhaust gas from cars contains only small amounts of sulfur trioxide, etc. (the sulfur content of gasoline amounts to 0.03%),the content of sulfuric acid in the air near roads and in narrow streets and tunnels may be high enough to irritate and harm the respiratory passages of people with asthmatic or allergic ailments. Several measures have been proposed to suppress the emission of sulfur trioxide from cars without relinquishing the use of the catalytic converters (Pierson, 1976). Among the suggestions discussed are fuel desulfurization, oxygen limitation, catalyst reformulation, and chemical trapping. Hitherto, the suppression of the sulfur trioxide emission has been limited. The transient formation and reduction of sulfur trioxide on an unsupported platinum catalyst, in the presence of excess carbon monoxide with respect to sulfur dioxide, was recently studied by Olsson and Schoon (1985). On the basis of this study, we wanted to test whether or not the emission of sulfur trioxide could be strongly suppressed by a proper choice of the temperature of the inflow, or by
* Author t o whom correspondence should be addressed. 0196-4305/86/1125-0528$01.50/0
a periodic processing of the oxygen content, or by other kinds of cyclic operation. It should be noted that the emission of sulfuric acid and sulfates from cars provided with catalytic converters was found to be much less in cyclic operation (as in ordinary driving in densely built-up areas) than could be expected on the basis of data from stationary experiments (Pierson, 1976). Experimental Methods Equipment. The experiments were performed with a single-channel element (length 11 mm) of a commercial monolithic Pt, Rh catalyst. The cross section of the channel was square-shaped (1.1mm). The channel element was mounted in a steel tube placed in an oven according to Figure 1. Analyses. The separation and determination of the components in the gas were performed in the same way as reported recently (Olsson and Schoon, 1985). Results a n d Discussion I. Pretreatment of the Catalytic Channel Element. In order to stabilize the activity of the catalyst, it was pretreated by alternate oxidation in the presence of oxygen and sulfur dioxide and reduction in the presence of carbon monoxide. Every oxidation and reduction cycle lasted for 1 h. Figure 2 shows the sulfur dioxide concentration in the outflow vs. the time of reaction. The concentration is given as the ratio of outflow concentration to inflow concentration. The sulfur dioxide concentration in the 0 1986 American Chemical Society
