Hybrid-phase catalysts selective

An important research area of catalysis is the heterogenization of metal complexes showing excellent activity and selectivity in the homogeneous phase (hybrid catalysts) [1]. The main advantage of supported metal complexes over unsupported ones is the ease of separation from the reaction media, which makes them economically convenient [2]. On the other hand, the main problems related with the heterogenization on solid supports are metal complex leaching and decrease in catalytic activity. 

There are some excellent review articles on different aspects of mesostructured materials, such as synthesis, properties, and applications. " Extensive research effort has been devoted to the exploitation of new phases (lamellar, cubic, hexagonal structures), expansion of the pore sizes (about 2-50 nm are accessible), and variable framework compositions (from pure silica, through mixed metal oxides to purely metal oxide-based frameworks, and inorganic-organic hybrid mesostructures). Another research focus is on the formation of mesostructured materials in other morphologies than powders, e.g. monolithic materials and films, which are required for a variety of applications including, but not limited to, sensors (based on piezoelectric mass balances or surface acoustic wave devices), catalyst supports, (size- and shape-selective) filtration membranes or (opto)electronic devices. The current article is focused... 

Metal-salen complexes immobilized on amorphous or mesostructured SiO were also investigated as acid-base catalysts for the cycHc carbonates synthesis imder continuous operation in gas phase. Despite the high selectivity to the cyclic carbonates the major drawback of these organic-inorganic hybrid catalysts were the catalyst deactivation, likely due to the cleavage of bonds which link the salen ligand and SiO imder the reaction conditions [78,82,106-108,111-113]. 

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