Ruthenium-silica, catalysts, structure

The copper EXAFS of the ruthenium-copper clusters might be expected to differ substantially from the copper EXAFS of a copper on silica catalyst, since the copper atoms have very different environments. This expectation is indeed borne out by experiment, as shown in Figure 2 by the plots of the function K x(K) vs. K at 100 K for the extended fine structure beyond the copper K edge for the ruthenium-copper catalyst and a copper on silica reference catalyst ( ). The difference is also evident from the Fourier transforms and first coordination shell inverse transforms in the middle and right-hand sections of Figure 2. The inverse transforms were taken over the range of distances 1.7 to 3.1A to isolate the contribution to EXAFS arising from the first coordination shell of metal atoms about a copper absorber atom. This shell consists of copper atoms alone in the copper catalyst and of both copper and ruthenium atoms in the ruthenium-copper catalyst. 

Hong, J., Chernavskii, P.A., Khodakov, A.Y., and Chu, W. Effect of promotion with ruthenium on the structure and catalytic performance of mesoporous silica (smaller and larger pore) supported cobalt Fischer-Tropsch catalysts. Catalysis Today, 2009, 140, 135. 

The synthesis of SiOa-supported iodoarene-RuCls bifunctional catalysts 142 and 143 consists of building a suitable ligand structure, 140 or 141, on the surface of commercial aminopropyl silica 139, followed by complexation with RuCls (Scheme 5.43) [114]. The amounts of RuCls and iodine loaded on the surface of silica gel were determined by elemental analyses of chlorine and iodine. The loadings of iodine and ruthenium for catalyst 142 are 0.60 and 0.06 mmol g" and for catalyst 143 0.62 and 0.05 mmol g respectively. For... 

An example for a non-structure-sensitive reaction is provided by Davis et al. [102], who investigated the liquid-phase hydrogenation of glucose over carbon and silica based ruthenium catalysts with particle sizes between 1.1 and 2.4 run. Depending on catalyst loading which was between 0.56 wt.% and 5 wt.%, dispersion decreased from 91% to 43%. At the same time, TOFs varied only insignificantly in a range between 0.21 1/s and 0.32 1/s. 

Vazquez-Zavala, A., Fuentes, S., Pedraza, F. (1994). The Influence of Sulfidation on the Crystalline Structure of Palladium, Rhodium and Ruthenium Catalysts Supported on Silica. Applied Surface Science, Vol.78, No.2, (June 1994), pp. 211-218, ISSN 0169-4332... 

Ir, Os, Fe, Cu, Mo, Pd, Re, and Rh in water-shift reaction was explored by dissolving them into the silica gel-supported IL [BMMIm][OTf] phase [106]. Finally, several ruthenium complexes with specific structures, that is, [PhNMejllRufCOljClj], [Ru(phen)(CO)3][Ru(CO)3Cl3], and [MMIm][Ru(CO)3Cl2l], were found to be active at 120 °C at ambient pressure. Noteworthy, this catalyst was very stable and without any deactivation after 20 h. Figure 2.37. Furthermore, although it cannot be explained well currently, only ruthenium complexes showed reasonable stability over 24 h time-on-stream. 

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