Surface and Subsurface Dynamics of the Intermetallic Compound ZnNi in Methanol Steam Reforming

The intermetallic compound ZnNi has been tested as unsupported powder catalyst in methanol steam reforming, showing severe performance changes during the process. Results from in situ XPS experiments proved the decomposition of the surface of ZnNi by Zn oxidation and complete desegregation of Ni. The decomposition of ZnNi even extends toward the bulk, as proven by in situ DTA/TG and XRD. On the basis of these findings, the catalytic properties initially ascribed to ZnNi can not be attributed to the intermetallic compound but have to be assigned to a mixture of the decomposition products.