Paper Title
Positron Lifetime And Magnetization Studies Of Rare Earth Oxides As Desulfurization Adsorbents

Rare Earth Oxide (REOs) nanoparticle catalysts are used as Desulfurization Adsorbents. The nanoporosity of these catalysts may influence the diffusion characteristics that may affect the desulfurization absorption efficiencies. Positron annihilation lifetime spectrometer (PALS) is used to study the nanoporosity of metal oxide nanoparticle catalyst powders. Rare Earth Oxide (REOs) nanoparticle catalysts with Mn, Al, Ce, La, Fe, and Gd metal compositions were prepared using Evaporation Induced Self Assembly and Sol-gel methods to prepare catalyst granules followed by calcination and co-impregnation with Mn or Al. Different composition samples were examined by PALS before and after reaction, and after desulfurization. The positronium lifetime component provides the information on pore size (lifetimes) and concentration of pores (intensities). Al rich catalysts have larger nanopores with lesser concentration and higher fractional free volume (1.5 to 2 times) compared to all other REO catalysts without Al. The pore concentration has increased after catalytic reaction resulting in an increase in fractional free volume. This could be due to low oxygen content observed in post reaction samples as some of the oxides might have reduced to metals during the reaction and forming new pores. Magne. Index Terms—Desulfurization, Magnetization, Nano-porosity. Positron lifetime, Rare earth catalysts.