Gmok zyxwvutsrqpo Letters zyxwvutsrqp cy0 zyxwvutsrqponmlkjihgfedc = zyxwvutsrq defined in Eq. 13 = defined in Eq. zyxwvutsr 14 2 = kinetic constant zyxwvutsrqp (K/Ci,) y = kinetic constant (K/C,,) = nondiinensional deactivation rate constant zyxwvuts (kdC$Jk) LITERATURE CITED Chu, C., “Effect of Adsorption on the Fouling of Catalyst Pellets,”Znd. Eng. Chem. Fundamentals, 7, 509 (1968). Cole, J. D., Perturbation Methods in Applied Mathematics, Blaisdell, Waltham, Mass. (1968). De Vera, A. L., and A. Varma, “Substrate-Inhibited Enzyme Reaction in aTubular Reactor with Axial Dispersion,”Chem. Eng. Sci., 34,275 (1979). Do, D. D., and R. H. Weiland, “Catalyst Deactivation in an Isothermal CSTR with First-Order Chemical Kinetics,” Chem. Eng. J., (1979a). Do, D. D., and R. H. Weiland, ”Catalyst Deactivation in an Isothermal CSTR with N-th Order and Michaelis-Menten Kinetics,”Chem. Eng. J., (1979b). Do, D. D., and R. H. Weiland, “Consistency between Rate Expressions for Enzyme Reactions and Deactivation,” Biotech. Bioeng., 22,1087 (1980~). Ha, T. C., “Uniqueness Criteria of the Steady State in Automotive Catalysis,” Chem. Eng. Sci., 31, 235 (1976). Kam, E. K. T., and R. Hughes, “Nonisothermal Fouling of Catalyst Pellets Using Langmuir-Hinshelwood Fouling Kinetics,” AZChE J., 25, 359 (1979). Laidler, K., and P. S. Bunting, The Chemical Kinetics zy of Enzyme Action, 2nd ed., Oxford University Press, Oxford, England (1973). Lin, S. H., “An Analysis. of Immobilized Enzymatic Reaction in a Packed-bed Reactor with Enzyme Denaturation,”Chem. zy Eng. J., 14, 129 (1977). Nayfeh, A. H., Perturbation Methods, Wiley-Interscience, New York (1973). Pereira, C. J., and A. Varma, “Uniqueness Criteria of the Steady State in Automotive Catalysis,” Chem. Eng. Sci., 33, 1645 (1978). Manuscript receioedOctoberl,l979; reoisionreceioedApril28,andaccepted Mayl, 1980. Determination of Interaction Second Virial Coefficients; He-CO, System We have obtained values for interaction second virial coefficients of the helium-carbon dioxide system in the range 230 5 T/K 5 300. Our experimental technique is essentially the Burnett mixing method described by Hall and Eubank (1973, 1974). We have modified the analysis to account for higher-order effects and to detect significant systematic errors. We also report virial coefficients for the pure components: helium in the range 100 I T/K I 300 and carbon dioxide at 300 K. SCOPE Interaction second virial coefficients, B,,, contain informa- tion about mixtures which is essential for both theoretical and practical applications. Within statistical mechanics, B,, reflects molecular interactions between unlike molecules and provides insight for theoretical mixture models. On the practical side, B,, is necessary for thermodynamic calculations at low pressure when the application dictates use of the (truncated)virial equa- tion. The normal method for obtaining B,, is reduction of mixture second virial coefficients, B,. This is the most obvious but least accurate method. The sources of inaccuracies are experimen- tal errors in the B,, and B, as well as any errors in composition determination. Edwards and Roseveare (1942) appear to have pioneered this method. Knobler et al. (1959) developed a sig- nificantly better technique: the differential pressure method. Correspondence concerning this paper should be addressed to K R Hall 0001-1541-80-33740954-%0125 “The American Institute of Chemical Engineers, 1980 1. C. HOLSTE, M. Q. WATSON, M. T. BELLOMY, P. T. EUBANK, and K. R. HALL Chemical Engineering Department Texas A&M University College Station, T X 77843 Their technique eliminated composition and B, as experimen- tal parameters but retained the Bii explicitly and ignored cor- rections for the effects of higher-order terms in the virial equation. Although other procedures are possible for obtaining Bij (reduction of vapor-liquid equilibrium data; analysis of chromatographic data), these two techniques have produced the bulk of the B, data and essentially all of the precise values. In this projedt, we extend a technique for isothermal deter- mination of Bij originally proposed by Hall and Eubank (1973). Their method was “direct” in that the pure-component virial coefficients, B,$, did not appear explicitly. Because Bii was a principal source of error in previous methods for obtaining Bij, the direct method appeared to have potentially greater accuracy. We chose to evaluate the method with mixtures of simple molecules, because they are more tractable for theoret- ical studies. This particular test involves helium (a spherical, nonpolar molecule) and carbon dioxide (a linear, quadrupolar molecule). Page 954 November, 1980 AlChE Journal (Vol. 26, No. 6)