Catalytic cleaning of polluted air : reaction engineering problems and new solutions

Abstract

Integration of regenerative heat exchange into a catalyst bed enables auto-thermal operation of catalytic purification of polluted air with a low content of combustible pollutants. Concentrations corresponding to an adiabatic temperature rise of less than 20°C can be handled without introduction of additional fuel. For higher concentrations, a technique involving side-stream withdrawal allows utilization of the total heat of combustion at the highest reactor temperature. Heat recovery by integrated heat exchange gives rise to an unusual behavior of the reactor. Based upon an analogy to fixed-bed reactors with integrated countercurrent heat exchange, simple equations are derived for reactor design and operation. Substantial reduction in pressure loss and in the volume of the packed bed can be obtained by replacing conventional catalyst packings by monolithic catalysts. The corresponding relationships are briefly discussed.