Evaluation of calcination effect on KL zeolite-supported ruthenium particles by use of electron microscopy and hydrogen chemisorption

The combined application of H2 chemisorption and Transmission Electron Microscopy (TEM) techniques was used to verify the influence of previous calcination with air in the decomposition of ruthenium precursors introduced by ionic exchange in zeolite KL, before Ru reduction to the metallic state. This zeolite was used in basic form CsKL and promoted with barium. The exposition of the Ru samples to an oxidant atmosphere, before reduction with H2, resulted in materials with metallic particles of higher average size. The samples heated directly with a mixture of N2/H2 showed homogeneous metallic particle dispersion with sizes in the range of 1.5–5 nm.