Modelling catalytic combustion of carbon monoxide and hydrocarbons over catalytically active wire meshes

A new way of preparing catalytically active wire meshes through a thermal-s pray technique is described. A metal substrate (e.g. Kanthal AF) was plasma -sprayed with a composite ceramic/polymer-powder. The polymer content of th e sprayed layer was burnt off whereupon a well-defined macro-porosity was c reated. By treating the so obtained material with an alumina-sol the specif ic surface area could be increased by a factor of 50 or more. The ceramic l ayer was finally activated with precious metals through an impregnation ste p. A numerical model was developed to compare the performance of wire-mesh- , monolith- and pellets catalysts. The model describes the resistance to in ternal and external mass- and heat transfer and the effects of axial disper sion. The wire-mesh model was verified through experiments. Different evalu ation parameters were derived to compare the catalyst performance relative to the catalyst volume, the geometric weight, the catalyst weight, the pres sure drop and the temperature response. Wire-mesh catalysts offer the follo wing advantages: high mass and heat transfer numbers, moderate pressure dro p, insignificant effects of pore diffusion and axial dispersion, thermal an d mechanical strength, geometric flexibility, excellent thermal response, s implicity in the catalyst recovery. The cost of a wire-mesh catalyst is exp ected to be competitive to other alternatives. (C) 1999 Elsevier Science S. A. All rights reserved.