CATALYZED COMBUSTION OF LEAN FUEL/AIR MIXTURES

The effect of catalytic surface activity on gas phase and surface reaction ignition temperatures was studied for H/sub 2/-, C/sub 3/H/sub 8/-, and C/sub 2/H/sub 6/-air mixtures flowing over a platinum and a quartz surface. It was found that the gas phase ignition temperature is a function of catalyst surface reactivity. That is at lower temperatures the quartz surface was essentially noncatalytic and resulted in gas phase ignition temperatures up to 100/sup 0/K lower than with the platinum surface. At increased surface temperatures the catalytic activity of the quartz surface approached that of the platinum and gas phase ignition temperatures were identical for both surfaces. A detailed study of C/sub 3/H/sub 8/ oxidation on a platinum surface showed that for temperatures less than 670/sup 0/K, CO is the primary oxidation product and for temperatures greater than 870/sup 0/K, complete oxidation to CO/sub 2/ occurs. 8 figures.