Ru-Sn sol—gel catalyst

Hajek, Jan Murzin, Dmitry Yu. Liquid-Phase Hydrogenation of Cinnamaldehyde over a Ru-Sn Sol-Gel Catalyst. E Evaluation of Mass Transfer via a Combined ExperimentaFTheoretical Approach, Industrial Engineering Chemistry Research 2004), 43(9), 2030-2038... 

Preparation and properties of bimetallic Ru-Sn sol-gel catalysts influence of catalyst reduction... 

For parallel -consecutive reactions, as examplified (Figure 4.18) by cinnamaldehyde hydrogenation over a Ru-Sn sol-gel catalyst,... 

Figure 4.20. Reactants concentration as a function of time in cinnamaldehyde hydrogenation- mechanism (4.129) ( J. Hajek, J. Wama, D.Yu. Murzin, Liquid-phase hydrogenation of cinnamaldehyde over Ru-Sn sol-gel catalyst. Part II...

Heterogeneous catalytic hydrogenation of cinnamaldehyde over a Ru/Y zeolite shows quite different behavior (Figure 4.24) contrary to the situation illustrated above for a Ru-Sn sol-gel catalyst. Namely selectivity to cinnamylalcohol is increasing with conversion which cannot be explained by conventional treatment of parallel-consecutive reactions calling for some other explanations. One possibly is in-situ formation of active sites selective for hydrogenation of the C=0 bond. 

For parallel-consecutive reactions, as exemplified (Fig. 4.31) by cinnamaldehyde hydrogenation over a Ru-Sn sol—gel catalyst, selectivity to the intermediate products follows behavior similar for consecutive reactions, but with lower (<100%) values of initial selectivity (Fig. 4.32)... 

Ru-Sn/SiOa catalysts were prepared by the sol-gel method. The influence of the reduction procedure and modification with sodium was investigated. The properties of the chemically reduced catalysts were compared to non-reduced and sodium-modified catalysts. The influence of Ru/Sn metals ratio was also studied. Physical characterization and liquid-phase hydrogenation of cinnamaldehyde demonstrated the high importance of the chemical reduction in the preparation of tested sol-gel catalysts. The highest selectivity to cinnamylalcohol was achieved on catalysts of 5%Ru-2.5%Sn/Si02 type (70%). Sodium modification of catalysts decreased the formation of acid catalysed side products and increased the yield of saturated aldehyde. The hydrogenation properties were dependent on Ru/Sn ratio. 

Hajek J, Maki-Arvela P, Toukoniitty E, Kumar N, Salmi T, Muizin DY (2004) The effect of chemical reducing agents in the synthesis of sol-gel Ru-Sn catalysts selective hydrogenation of cinnamaldehyde. J Sol-Gel Sci Technol 30 187-195... 

Novel catalysts (141) such as Ru-Sn and Re-Sn can be used to hydrogenate fatty acids or methylesters to fatty alcohols. Using these catalysts, the hydrogenation can be carried out at the same temperature (250°C) but lower pressure (50 bars), and the unsaturations present remain unaffected. The presence of tin has been found to be instrumental in the preservation of the unsaturation during hydrogenation. Ru-Sn supported on alumina was found to be most selective when they were prepared via the sol-gel method. 

This work is focused on the investigation and improvement of sol-gel Ru-Sn/SiOa catalysts. Main attention is dedicated to study the chemical reduction benefits involving metals reduction and chemical and physical stabilization. Influence of Ru/Sn ratio and sodium modification on catalysts activity and selectivity will be also discussed. 

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