Mass-transfer enhancement by static mixers in a wall-coated catalytic reactor

Abstract Using CO oxidation in a wall-coated tubular reactor, the enhancement of radial mass transfer by a static mixer was investigated. Experiments were conducted at various flow rates, CO concentrations and temperatures. Flow rates were chosen such that the flow remains in the laminar regime. Several effects were observed: light-off occurred at higher temperatures for higher flow rates and higher CO concentrations. Lower conversions were obtained for higher flow rates. In general, measured conversions were higher with the static mixer, compared to an empty tube under mass-transfer limited conditions. An expression for the Sherwood number, Sh =2+0.059 Re , was calculated for the system with static mixers. Our study demonstrates that the performance of wall-coated reactors can be significantly enhanced using static mixers. This reactor may be a new tool for reaction engineers, e.g., to replace catalyst-pellet-filled tubes in multi-tubular reactors to suppress hot-spot formation or for heterogeneously catalyzed viscous liquid-phase reactions.

[1]  A. Storck,et al.  Mass transfer and pressure drop performance of turbulence promoters in electrochemical cells , 1981 .

[3]  Fernando J. Muzzio,et al.  Numerical characterization of low Reynolds number flow in the Kenics static mixer , 1998 .

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

[5]  Duu-Jong Lee,et al.  Micromixing efficiency in static mixer , 2001 .

[6]  S. Kolaczkowski.  Modelling catalytic combustion in monolith reactors - challenges faced , 1999 .

[7]  J. Votruba,et al.  Heat and mass transfer in honeycomb catalysts—II , 1975 .

[8]  Jimmie L. Williams,et al.  Monolith structures, materials, properties and uses , 2001 .

[9]  Julio M. Ottino,et al.  A case study of chaotic mixing in deterministic flows: The partitioned-pipe mixer , 1987 .

[10]  L. Schmidt,et al.  The Effect of Ceramic Supports on Partial Oxidation of Hydrocarbons over Noble Metal Coated Monoliths , 1998 .

[11]  Jacob A. Moulijn,et al.  Monolithic Reactors for Fine Chemicals Industries: A Comparative Analysis of a Monolithic Reactor and a Mechanically Agitated Slurry Reactor , 1999 .

[12]  J. Arimond,et al.  Modeling of Continuous Mixers in Polymer Processing , 1985 .

[13]  B. Andersson,et al.  Mass transfer in monolith catalysts–CO oxidation experiments and simulations , 1998 .

[14]  R. Brück,et al.  Design Criteria of Metallic Substrates for Future Catalyst Applications; Part III , 1997 .

[15]  W. Tao,et al.  Experimental Study on Effect of Interwall Tube Cylinder on Heat/Mass Transfer Characteristics of Corrugated Plate Fin-and-Tube Exchanger Configuration , 1992 .

[16]  Jimmy E. Antia,et al.  n-Hexane cracking on binderless zeolite HZSM-5 coated monolithic reactors , 1997 .

[17]  P. Drtina,et al.  Numerical simulation of the fluid flow and the mixing process in a static mixer , 1995 .

[18]  M. Huff,et al.  Acetylene formation during the catalytic oxidative dehydrogenation of ethane over Pt-coated monoliths at short contact times , 1997 .

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

[20]  A. Holmgren.  Enhanced Mass Transfer in Monolith Catalysts with Bumps on the Channel Walls , 1999 .

[21]  E. B. Nauman,et al.  Residence time distributions of power law fluids in motionless mixers , 1985 .

[22]  L. Fletcher,et al.  Heat transfer in a three-dimensional channel with baffles , 1996 .

[23]  S. P. Waldram,et al.  Monolithic reactors: mass transfer measurements under reacting conditions , 1992 .

[24]  P. Bardhan.  Ceramic honeycomb filters and catalysts , 1997 .

[25]  John W. Geus,et al.  Monoliths in catalytic oxidation , 1999 .

[26]  M. Alvarez,et al.  Mixing in Globally Chaotic Flows , 1997 .

[27]  Bengt Andersson,et al.  Monolithic Catalysts for Nonautomobile Applications , 1988 .

[28]  S. Succi,et al.  Mass Transfer Improvements in Catalytic Converter Channels: An Hybrid BGK-Finite Volume Numerical Simulation Method , 1997 .