X-ray absorption fine structure studies on nickel phosphide catalysts for the non-oxidative coupling of methane reaction using a theoretical model

SiO2-supported Ni phosphide catalysts are highly active toward the non-oxidative coupling of methane (NOCM) reaction, and their catalytic activity is strongly dependent on Ni:P ratio. We analyzed using X-ray absorption fine structure (XAFS) to elucidate structure-catalytic relationship. Because only Ni2P was available as a reference material, we calculated theoretical XAFS based crystal structures FEFF program compared them with experimental spectra catalysts. demonstrated that P ratios 1:1, 2:1, 3:1 consisted mainly Ni2P, Ni12P5, Ni3P, respectively. found exhibited highest NOCM because its optimum balance C–H cleavage coke formation. This analysis simulation could be used identify supported compounds.