A study on the thermal behavior of structured plate-type catalysts with metallic supports for gas/solid exothermic reactions

The heat transfer characteristics of seven di!erent samples of coated plate-type structured catalysts with highly conductive metallic supports were investigated using the model reaction of CO oxidation over Pd/c-Al 2 O 3 . In the case of supports made of aluminum hot spot temperatures were moderate, and the thermal behavior of the structured catalysts was solely controlled by the heat transfer resistance at the interface between catalyst and reactor wall. Temperature gradients were markedly more signi"cant in the case of a support with identical geometry but made of steel, due to a tenfold reduction of the intrinsic material conductivity. They were still greater in the case of a steel support with thinner plates. For aluminum supports, experiments with a fourfold more active catalytic washcoat and with a modi"ed con"guration of the structured support con"rmed that an isothermal behavior is approached even for conditions corresponding to an adiabatic temperature rise of about 8003C, and that such results can be scaled up to di!erent geometries of the structured systems if the washcoat-to-support volume ratio is conserved. Finally, the wall heat transfer coe$cient was enhanced by a design of the aluminum support with improved thermal contact at the wall. A simple 1D analysis, based on independent intrinsic kinetics, yielded estimates of the overall wall heat transfer coe$cient in the range 80}120 W/(m2 K). ( 2000 Elsevier Science Ltd. All rights reserved.

[1]  R. Reid,et al.  The Properties of Gases and Liquids , 1977 .

[2]  J. Moulijn,et al.  Modelling of heat transfer in metallic monoliths consisting of sinusoidal cells , 1994 .

[3]  G. Froment,et al.  Modeling and simulation of a honeycomb reactor for high‐severity thermal cracking , 1991 .

[4]  William H. Beyer,et al.  CRC standard mathematical tables , 1976 .

[5]  Enrico Tronconi,et al.  Design of novel monolith catalyst supports for gas/solid reactions with heat exchange , 2000 .

[6]  Pio Forzatti,et al.  Synthesis of alcohols from carbon oxides and hydrogen. 1. Kinetics of the low-pressure methanol synthesis , 1985 .

[7]  T. L. Wayburn,et al.  Homotopy continuation methods for computer-aided process design☆ , 1987 .

[8]  S. E. Voltz,et al.  Kinetic Study of Carbon Monoxide and Propylene Oxidation on Platinum Catalysts , 1973 .

[9]  M. Zwinkels,et al.  Preparation of combustion catalysts by wash coating alumina whiskers-covered metal monoliths using a sol-gel method , 1995 .

[10]  G. Froment,et al.  Chemical Reactor Analysis and Design , 1979 .

[11]  Gerhart Eigenberger,et al.  Fixed‐Bed Reactors , 2000 .

[12]  A powerful method for Hougen—Watson model parameter estimation with integral conversion data , 1974 .

[13]  Michel Prigent,et al.  Three-way catalytic converter modelling: fast- and slow-oxidizing hydrocarbons, inhibiting species, and steam-reforming reaction , 1998 .

[14]  Arvind Varma,et al.  Reaction kinetics on a commercial three-way catalyst: the carbon monoxide-nitrogen monoxide-oxygen-water system , 1985 .

[15]  Enrico Tronconi,et al.  Continuous vs. discrete models of nonadiabatic monolith catalysts , 1996 .

[16]  G. Groppi,et al.  Development of novel structured catalytic reactors for highly exothermic reactions , 2000 .

[17]  William H. Press,et al.  The Art of Scientific Computing Second Edition , 1998 .

[18]  Jacob A. Moulijn,et al.  Monoliths in Heterogeneous Catalysis , 1994 .

[19]  L. Doraiswamy,et al.  Heterogeneous reactions: Analysis examples and reactor design. Vol. 1: Gas solid and solid-solid reactions , 1984 .