Microstructured catalysts selective hydrogenations

The aim of the present article is to report the use of carbon nanotubes as eatalyst support for a palladium active phase in the selective C=C hydrogenation of cinnamaldehyde in liquid-phase. Such reaction is of interest especially in the fine chemieal domain where speeific hydrogenation is actively sought. The catalytic performance was evaluated by comparing the observed activity and selectivity with those of a commercial catalyst supported on a high surfece area activated chareoal. The influenee of the support morphology and microstructure on the hydrogenation activity and selectivity will also be discussed. 

The clusters M40[(CO)9Co3CC02]6 (M = Zn, Co) were used as single-source precursors for porous, high surface area materials, referred to as ZnCo and CoCo, respectively. These materials were catalysts for hydrogenation of 1,3-butadiene at 50-573 K. At <423 K, both catalysts maintained activity for up to 4 days on stream. CoCo has both higher activity and different selectivity than conventionally prepared Co on silica. It was suggest that both the composition and microstructure derived from the precursor contribute to the catalytic behavior. At 573 K, the activity of these catalysts decrease due to the formation of carbon on the surface and the partial collapse of the porous structure. ... 

Structured supported ionic liquid-phase (SSILP) catalysis is a new concept that combines the advantages of ionic liquids (ILs) as solvents for homogeneous catalysts with the benefits of structured solid catalysts. In an attempt to prepare a homogeneous IL film on a microstructured support, SMFs were coated by a layer of carbon nanofibers as described above. An IL thin film was then immobilized on the CNF/SMF support. The high interfacial area of the IL film enabled the efficient use of a transition metal catalyst for the selective gas-phase hydrogenation of acetylenic compounds [267,268]. 

Many reported MSR used for gas-hquid- sohdreactions are micro packed beds. An advantage of microstructured packed bed for hydrogenation processes stems from the fact that active and selective catalysts are commercially available. 

V. Cominos, V. Hessel, C. Hofmann, et at Selective oxidation of carbon monoxide in a hydrogen-rich fuel cell feed using a catalyst coated microstructured reactor. Catal. Today 2005, 110, 140-153. 

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