Operation of Porous Membrane Reactors

Ru(N0)(N03)3 solution. After drying, the support is calcined at 550°C in air to obtain a bimodal catalytic support (Ru/Y-Al203/a-Al203). Finally, a homogeneous silica membrane is prepared on the outside surface of the bimodal catalytic support using polyhedral oligomeric silses-quioxane (POSS) as precursor, by the sol-gel method. 

The integration of the selective and catalytic functions into one single layer usually demands contradicting material properties. For example, to achieve high selectivity the diffusion of products inside the material should be low, whereas efficient use of the catalytic properties requires the diffusion of products to be high. This conflicting demand on material properties can be avoided by accommodating the selective and catalytic features in two different distinct layers that are in close physical contact. This approach also allows independent optimization of the selective and catalytic properties. 

A non-uniform and precisely controlled position of the catalyst within the membrane pores can impact the reactor performance positively [17]. A modeling study on the first-order reaction in a catalytic membrane indicates that a Dirac-delta function of the concentration of catalyst in the membrane, placed at the feed side, allows the highest conversions. In other words, it is better to promote the reaction as close to the membrane as possible (on its surface), letting the rest of the membrane work as a mere separator of some of the reaction products [24]. The membrane structure is critical to the preparation of non-uniform catalytic membranes. If a sufficiently homogeneous membrane structure is present, simple impregnation may be sufficient to obtain a controlled, non-uniform distribution of active materials. 

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OPERATION OF POROUS MEMBRANE REACTORS 2.6.1 Packed Bed Membrane Reactors... 

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