Theoretical study on hydrogenation catalysts containing a metal hydride as additional hydrogen supply

A hypothetical hydrogenation catalyst consisting of porous, catalytically active particles embedded with metal hydride powder was evaluated. The metal hydride provides temporarily additional hydrogen if the mass transfer rate of the hydrogen to the internal of the particle is not sufficient. A numerical model was developed to describe the hydrogenation of components in the liquid phase of a batch reactor. With this model two different reactions schemes were simulated. The first showed that the average hydrogen concentration increases with a metal hydride inside the catalyst particles. A reduction of byproduct formation and an increase in selectivity could be realized. The next system was the hydrogenation of succinonitril. Undesired products are oligomers and cyclic compounds, which are formed in the centre of the particle in the absence of hydrogen. The formation of these products is suppressed when a metal hydride is present. Another advantage is that the process can now be operated under more favorable conditions (lower pressure and higher initial succinonitril concentration) without significantly affecting the selectivities and byproduct formation.