Hexene hydrogenation, shape selectivity

A Ni(salen) complex [salen = bis(salicylidene)ethylenediamine] encapsulated in zeolite is highly efficient in the hydrogenation of simple alkenes (cyclohexene, cyclooctene, 1-hexene).451 This method, which is the encapsulation of metal complexes into the cavities of zeolites, offers the unique possibility of shape-selective... 

A novel method for the preparation of metal containing small pore zeolites is described. The metal is introduced at elevated temperatures by solid state ion exchange. The zeolites obtained by the new method are highly shape selective. As an example, the competitive hydrogenation of an equimolar mixture of hexene-(l) and 2,4,4-trimethylpentene-(l) over various platinum, palladium and rhodium containing 8-membered ring zeolites was studied. 

A series of new crystalline titanates (CT) are shown to have considerable potential as catalysts supports. For Pd supported catalysts, the catalytic activity for pyrene hydrogenation was substaniatially different depending on the type of CT, and one was substantially more active than Pd on hydrous titanium oxide (HTO). For 1-hexene hydrogenation the activities of the new CTs were approximately the same as for the hydrous metal oxide siqtports. Stereochemical effects, such as shape selective catalysis, ars to be occurring when pyrene is hydrogenated. 

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