Comparison of the CO and D-2 oxidation reactions on Pd supported on MgO(100), MgO(110) and MgO(111)

Oxidation of D-2 and CO on oxygen pre-exposed 200 nm thick Pd films, epitax ially grown on MgO(100), MgO(110) and MgO(111), has been investigated in th e temperature range 100-300 degrees C. Oxygen initial sticking coefficients have been determined to be close to 1 for the 100 and 110 films, and aroun d 0.8 for the 111 film. The sticking coefficient and reactive sticking coef ficient for CO oxidation on Pd/MgO(100) is also close to 1, and the maximum reactive sticking coefficient for hydrogen oxidation is determined to be a round 0.9 at temperatures above 200 degrees C. It is shown that the reactiv ities for the different surfaces vary strongly with surface and oxygen cove rage, and the consequence of this for supported particle catalysts is point ed out. (C) 1999 Elsevier Science B.V. All rights reserved.