The effect of Li on structure of supported Rh particles in zeolite

We prepared Rh ion exchanged Y-type zeolite (RhY) and Li-doped RhY (Li/RhY) catalysts and studied the structure transformation of Rh intercalated spec ies during CO adsorption and CO2 hydrogenation by EXAFS and TEM. We found t hat Rh particles in RhY initially supported inside the zeolite cage as 1.3 nm spherical or hemispherical particles. CO exposure of the Fresh RhY cause d formation of atomically dispersed Rh species. After CO2 hydrogenation and following reduction, the Rh particles aggregated to form 3.3 nm particles on the outer surface. Meanwhile, Rh particles in Li/RhY were embedded in th e zeolite cages, which were narrowed by Li deposition on the wall. The size of the Rh panicles was 0.8 nm in diameter. The Rh particles in Li/RhY were stable under reduction, CO adsorption, and CO2 hydrogenation conditions. W e concluded Li additive changed the stability of Rh particles in the superc age by modifying surface hydroxyl group concentration.