Rhodium-containing silicalite-1 zeolites are investigated by using heterogeneous parahydrogen-induced polarization (HET-PHIP) NMR technique. Both liquid-state and in-situ magic angle spinning (MAS) NMR experiments are performed to explore the PHIP effect...

The structure and properties of porous mixed metal oxide catalysts (Ga x Al2–x O3 and Pt/Ga x Al2–x O3) derived from calcination treatment of bimetallic MIL-53­(Ga, Al) precursors were comprehensively characterized using XRD, N2 adsorption–desorption isotherms, TEM, and solid-state NMR. Both Ga and Pt species are highly dispersed in Pt/Ga0.1Al1.9O3 and Pt/Ga0.5Al1.5O3 catalysts with low Ga content, whereas Ga2O3 particles are present in Ga1.0Al1.0O3 and Ga1.5Al0.5O3 catalysts with high Ga content. Well-mixed Al and Ga species in the calcined Ga0.1Al1.9O3 and Ga0.5Al1.5O3 samples are identified from 1H–71Ga S-RESPDOR and 1H–27Al TRAPDOR NMR experiments. The coordination states and relative amounts of Al and Ga species in the MIL-53­(Ga, Al) derivatives are determined by 27Al and 71Ga MAS NMR measurements. It is found that Pt species are readily anchored with pentacoordinate Al, favoring the formation of tetrahedral GaIV species, and the synergy between highly dispersed Pt and tetrahedral GaIV active species in Pt/Ga0.1Al1.9O3 and Pt/Ga0.5Al1.5O3 catalysts renders their superior catalytic performance with high conversion and good recyclability toward the propane dehydrogenation reaction.