Große Übergangsmetallcluster, VIII. Wie verhalten sich trägergestützte Rh₅₅‐Cluster im Hydroformylierungsprozeß?

Abstract

Large Transition Metal Clusters, VIII. ‐ How Do Supported Rh55 Clusters Behave in the Hydroformylation Process? Two‐shell rhodium clusters of the type Rh55L12Clx [L = P(tBu)3, x = 20; L = PPh3, x = 6] can be anchored on TiO2 and Na‐ Y‐zeolite. High resolution transmission electron microscopy (HRTEM), BET, and DSC investigations prove that the clusters, about 20 Å in diameter, are fixed on the entrances of the micropores of the supports. The supported clusters catalyze the hydroformylation of ethene and propene variously. During the hydroformylation of ethene without a solvent or in aqueous suspension the catalyst is inactive after a few cycles. However, there is no loss of activity even after 27 experiments if propene is hydroformylated in an aqueous medium.

Ordered porous materials as media for the organization of matter on the nanoscale

“…This pore size range corresponds to the sizes of ligand-stabilized metal clusters, such as the closed-shell clusters developed in Schmid's group. 21 Incorporation of such clusters in well-defined pore systems could stabilize the clusters against agglomeration, which easily occurs if the clusters lose their ligand sphere. Therefore this technique could be interesting for preparing supported catalysts with a stable dispersion of the noble-metal particles.…”