EXPLORING THE REACTIVITY OF ZEOLITE-SUPPORTED RH COMPLEXES

摘要

The use of model catalytic materials has been proven to be beneficial for understanding structure-catalytic properties relationships which can open new opportunities for the rational design of catalysts for specific applications. Although such materials have been prepared and examined in the past, the synthesis of model catalysts which are structurally uniform and incorporate well-defined active sites remains a major experimental challenge. In one approach to the synthesis of such materials the support is regarded as a rigid ligand capable of stabilizing organometallic complexes.Single site catalysts prepared via this organometallic route represent the current state-of-the-art in this area. For example, it has been shown that Rh(CO)2(acac) complexes are capable of reacting with surfaces of dealuminated Y zeolites and this reaction leads to the displacement of the "acac" ligand and to the formation of site-isolated and well-defined Rh(CO)2 species anchored inside the zeolite supercage. It has been also suggested that such Rh(CO)2 species retain their square-planar geometry upon anchoring and, in fact, two oxygen atoms located in the T4 ring of zeolite Y and coordinated to Al~(3+) cations represent binding sites for these species. Moreover, it was established that carbonyl ligands in these complexes are quite reactive and exposure to C2H4 results in the formation of Rh(C2H4)CO complexes. In our current work we further explore the reactivity of Y-zeolite supported Rh(CO)2 species towards C2H1, H, CO/O2, and CO/NO gases.