Abstract
Using single catalyst pellets (5 mm) 15% Ptγ–Al2O3, we experimentally studied gas-phase benzene hydrogenation at normal pressure by thermocouple measurements of gas flow and the pellet center. Temperature of gas flow was varied in the range of 20 ‡C / 350 ‡C for three molar fractions of benzene vapor (0.1, 0.2, and 0.3) mixed with hydrogen. The ignition/extinction behavior of the flow-pellet temperature rise (maximum values up to 100 ‡C/ 200 dgC) is explained by internal-external mass transport limitations of the reaction rate and reaction reversibility at high pellet temperature. A simplified pseudobinary treatment of both multicomponent intrapellet mass transfer (in bimodal porous media) and multicomponent external mass transfer (under forced convection) is proposed on the basis of the analytical estimation. The validity of the suggested approach is confirmed by comparing the experimental data for benzene hydrogenation with rigorous (multicomponent) and approximated (pseudobinary) calculations obtained by using a mathematical model of a spherically symmetric pellet. The simplified approach appears to be quite accurate for reactions A+nH2=B of hydrogenation (n>0) or dehydrogenation (n<0) of sufficiently heavy compounds, i.e. if D AH ≈D BH >>D AB
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References
Buben, N. J., “Heat Regime of Pt Wire in Reaction of Hydrogen and Ammonia Oxidation,”Journ. of Physical Chemistry, Additional Vol. (1946) (in Russian).
Frank-Kamenetskii, D. A., “Diffusion and Heat Exchange in Chemical Kinetics,” New Jercey: Princeton Univ. Press (1955).
Eddings, E. G. and Sohn, H. Y, “Simplified Treatment of the Rates of Gas-Solid Reactions Involving Multicomponent Diffusion,”Ind. Eng. Chem. Res.,32,42 (1993).
Goossens, E., Donker, R. and Van den Brink, E, “Reactor Runaway in Pyrolysis Gasoline Hydrogenation,” Proceedings of the 1st International Symposium “Hydrotreatment and Hydrocracking of Oil Fraction,” Oostende, Belgium, February 17–19 (1997).
Graham, R R, Vidaurri, F. C, JR and Gully, A. J., “Catalytic Dehydrogenation of Cyclohexane: a Transport Controlled Model,”AIChE J.,14,473 (1968).
Haugaard, J. and Livbjerg, H., “Models of Pore Diffusion in Porous Catalysts,”Chem. Eng. Sci.,53, 2941 (1998).
Hugmark, G. A, “Mass and Heat Transfer from Rigid Spheres,”AIChE J.,13,1219 (1967).
Jackson, R., “Transport in Porous Catalysts,” Elsevier, Amsterdam (1977).
Johnson, M. F. L. and Stewart, W. E., “Pore Structure and Gas Diffusion in Solid Catalysts,”J. Catal.,4,248 (1965).
Khadilkar, M. R, Mills, P. L. and Dudukovic, M. P., “Trickle-bed Reactor Models for Systems with a Volatile Liquid Phase,”Chem. Eng. Sci.,54, 2421 (1999).
KiriUov, V. A., Kuzin, N. A., Kulikov, A. V, Lukyanov, B. N, Hanaev, V. M. and Shigarov, A. B., “Study of External Diffusion Regime of Gas Phase Reaction of Hydrocarbons Hydrogenation on Single Catalyst Pellet,”Theoretical Found. Chem. Eng. (in Russian),34, 526 (2000).
Krishna, R., “Problems and Pitfalls in the Use of the Fick Formulation for Intraparticle Diffusion,”Chem. Eng. Sci.,48, 845 (1993).
Krishna, R. and Wesselingh, J. A., “The Maxwell-Stefan Approach to Mass Transfer,”Chem. Eng. Sci.,52, 861 (1997).
Malinovskaya, O. A., Beskov, V. S. and Slinko, M. G., “Modeling of Catalytic Processes on Porous Pellets,” (in Russian), Nauka, Novosibirsk (1975).
Mason, E. A. and Malinauskas, A. P., “Gas Transport in Porous Media: The Dusty Gas Model,” Elseveier Science Publishers (1983).
Ostrovskii, N. M., Parmaliana, A., Frustery, F, Maslova, L. P. and Jordano, N., “Analysis of the Process of Benzene Hydrogenation on Monolith Catalyst Pt/Al2O3 with Honeycomb Structure,”Kinet. Katal. (in Russian),32, 78 (1991).
Papavassiliou, V., Lee, C, Nestlerode, J. and Harold, M. P., “Pneumatically Controlled Transport and Reaction in Inorganic Membranes,”Ind. Eng. Chem. Res.,36,4954 (1997).
Reid, R C, Prausnitz, J. M. and Poling, B. E., “Properties of Gases and Liquids,” 4-th Edition, McGraw-Hill, New York (1987).
Ruthven, D. M., “Principles of Adsorption and Adsorption Processes,” Wiley, New York (1984).
Stewart, W. E. and Prober, R., “Matrix Calculation of Multicomponent Mass Transfer in Isothermal Systems,”Ind. Eng. Chem. Fund.,3, 224 (1964).
Taylor, R. and Krishna, R., “Multicomponent Mass Transfer,” John Wiley and Sons, NY (1993).
Toor, H L., “Solution of the Linearized Equations of Multicomponent Mass Transfer,”AIChE Journal,10,448 (1964).
Wilke, G. R. and Lee, C. J., “Estimation of the Diffusion Coefficients for Gases and Vapors,”Ind. Eng. Chem.,47,1253 (1955).
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Shigarov, A.B., Fadeev, S.I., Mikhailova, I.A. et al. Simplified treatment of mass transfer for gas-phase hydrogenation/dehydrogenation of heavy compounds. Korean J. Chem. Eng. 19, 252–260 (2002). https://doi.org/10.1007/BF02698410
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DOI: https://doi.org/10.1007/BF02698410