Catalytic Properties of Ru Supported on Interlayered Montmorillonite

Abstract

Chemical and physical properties of interlayered montmorillonite were determined by Xray diffraction and adsorption of N₂ and organic compounds. When Al₂O₃ and ZrO₂ were introduced into the interlayer of montmorillonite, the interlayered montmorillonite had the interlayer spacing of 8Å and showed a high surface area (>320 m²⋅g^-1) which was fifteen times that of montmorillonite. The surface areas calculated from adsorption of methyl -substituted benzenes were about one-half those determined by N₂ adsorption, indicating the presence of narrow pores.
Ru cat alysts supported on these interlayered montmorillonite were prepared from three Ru compounds and they were characterized by adsorption of H₂ and CO and by electron microscopy. When Ru₃(CO)₁₂ or Ru(NH₃)₆Cl₃ were utilized, fairly well dispersed Ru catalysts were obtained.
Hydrogenation of the methyl-substituted benzenes and CO were examined over the Ru cat alysts. It was found that 1, 2, 3, 5-tetramethylbenzene (molecular size; 8.0Å) was hydrogenated with very low efficiency as compared with non- to tti-methyl -substituted benzenes. This is considered to be due to the slow diffusion of tetramethylbenezene in the interlayer space. Thi s result presumably originates from the shape selectivity of the supports and shows th at most of Ru particles locates in the interlayer space.
In the CO hydrogenation, product distribution of hydrocarbons shifted to lower hydrocar bons such as methane as major product (>60%) as compared with Ru supported on Al₂O₃. Possible reasons of this result were discussed.