Essential characteristics of exothermic reactions on catalyst surfaces with improved flame stability and combustion characteristics

A plurality of honeycomb catalyst bodies is employed in a reaction zone in a spaced-apart relationship. The distance between these catalyst bodies may vary over a wide range, and when more than two catalyst bodies are employed spaced-apart in a reaction zone, the distance between the catalyst bodies may vary. Sufficient space is provided between at least two, and preferably between each, of the catalyst bodies to enable commingling of the gases emanating from one catalyst body prior to passing through the next downstream catalyst body. Desirably, the velocity of the gases through the space between the catalyst bodies is turbulent so as to provide a more effective admixing of the reacted and unreacted gases. The spaces between the catalyst bodies may be referred to as open spaces, and thus there is no obstruction to the mixing between the bodies. The space between each catalyst required to obtain the desired mixing or commingling is dependent upon several variables such as the cross-sectional area of the flowthrough paths, the velocity of the gases, and the like. Preferably, the catalyst bodies are spaced apart at least the length of the flowthrough paths through the immediate upstream catalyst. The honeycomb catalyst bodies may be arranged such that the flowthrough paths of one catalyst body can be in or out of alignment with those of the next downstream catalyst body. When the flowthrough paths of adjacent honeycomb catalyst bodies are aligned, a greater distance between the catalyst bodies may be advantageous to provide the desired degree of mixing of the reactants and catalytically reacted products than the distance employed between catalyst bodies whose flowthrough paths are not aligned. The desired degree of commingling of these gases in the space between catalyst bodies may vary over a wide range. The degree of mixing should, however, be sufficient to ensure that the composition of the gases entering flowthrough paths of the next adjacent catalyst body does not vary substantially. In this manner, essentially unreacted gases which exit from a deactivated flowthrough path of a first catalyst body will commingle with at least partially reacted gases emitted from adjacent, catalytically-active flowthrough paths. The admixing of the gases provides a more or less uniform composition of gas at any point entering the next adjacent catalyst body. Excessively high concentrations or low concentrations of any component in the gas entering the next adjacent catalyst body will thus be avoided. By maintaining a substantially constant concentration of gases entering each catalyst body, several advantages are realized. The reactions can more precisely be controlled with respect to degree of completion, reaction conditions, response to change in reaction conditions, and the like. Furthermore, the method enables, if desired, a higher degree of completion of the catalytic reaction to be achieved than if a single catalyst body is employed having essentially the same overall volume.