Novel fabrication and catalysis of nano-structured Rh and RhPt alloy particles occluded in ordered mesoporous silica templates using supercritical carbon dioxide

Abstract

Mesoporous HMM-1 and FSM-16 supported monometallic Rh and bimetallic RhPt catalysts have been prepared by applying supercritical carbon dioxide (scCO₂) treatment (348 K and 16 MPa) to metal precursors impregnated on the supports followed by calcination and H₂-reduction. The catalysts thus prepared were characterized by CO chemisorption, XRD, TEM and IR spectroscopy to elucidate the morphology of the metal particles and support. The characterization data revealed that highly dispersed Rh and RhPt nano-sized particles (particle size <3 nm) were obtained after the scCO₂ treatment inside the mesoporous channels of the supports. Homogeneous alloy particles were obtained for the RhPt catalysts after the treatments. Catalytic performances were tested for butane hydrogenolysis. Marked enhancement in the catalytic activity and selectivity for ethane production due to central C–C bond scission was observed for the scCO₂ treated Rh and RhPt catalysts relative to the non-treated conventional catalysts.