Correlating Ethylene Glycol Reforming Activity with In Situ EXAFS Detection of Ni Segregation in Supported NiPt Bimetallic Catalysts

The structural changes in supported NiPt/C and NiPt/gamma-Al2O3 catalysts were investigated using in situ extended X-ray absorption fine structure (EXAFS) under aqueous phase reforming (APR) of ethylene glycol conditions. Reverse Monte Carlo is introduced to analyze the EXAFS data. Parallel reactor studies of APR of ethylene glycol showed that NiPt catalysts were initially more active than monometallic Pt catalysts. The enhanced activity was correlated to changes in the catalyst structure. Under APR conditions, Ni segregated to the surface of the catalysts, resembling Ni-terminated bimetallic surfaces that were predicted to be more active than Pt from theoretical and experimental studies on model surfaces.