Determination of Au and Pt in titanate nanotube catalysts by photon activation analysis

This study demonstrated the determination of Au and Pt concentrations in titanate nanotube-supported (abbreviated as TNT-supported) metal catalysts by photon activation and their catalytic activity with respect to metal concentration. An 18MV medical accelerator was used as photon source to activate the metals and generate radionuclides for gamma-ray spectroscopic analysis. Two TNT-supported metal catalysts, namely Au/NaTNT and Pt/MTNT (M=Na(+) and Cs(+)), were prepared and the Au and Pt concentrations and the respective loading efficiencies were determined. The detection sensitivities with respect to the photon activated radionuclides were estimated to select the most sensitive gamma rays for the determination of Au and Pt concentrations. The loading efficiency for Au/NaTNT decreased with increasing Au concentration prepared, while it was almost 100% for Pt loading in Pt/MTNT of various prepared Pt concentrations. The Au/NaTNT containing 2.53 wt% of Au effectively oxidized CO at a much lower reaction temperature than the lower concentration ones. For cinnamaldehyde hydrogenation reaction, the catalytic activity of Pt/TNT with different Pt loadings followed the order of 2.9>2.3>0.9>0.5 wt%. This photon activation technique, with minus interfering radionuclides in the gamma-ray spectra and induced radioactivities in the samples, is perfectly suited to the determination of metal concentrations in TNT-supported catalysts, that might contain considerable amounts of alkali metal ions.