Catalyst Immobilization in Membranes

By incorporating catalysts in membranes, a new environment is created around the catalyst which can in several ways influence the catalytic activity and selectivity of the catalyst. The membrane can block certain inhibiting compounds from the catalyst surroundings by steric exclusion or by decreasing the sorption tendency of that compound and/or its diffusion to the catalyst. Alternatively, it can facilitate the transport of desired compounds to the reactive sites. When incorporated in a membrane, other reactor setups can become available, e.g., with the two reagents contacting the membrane (and thus the immobilized catalyst) from the different sides.

Different methodologies exist to immobilize homogeneous catalysts in membranes: via a covalent or coordinative bond between the catalyst and the membrane, via electrostatic interactions between them, through steric occlusion of the catalyst in a matrix or through physical adsorption of the catalyst on the membrane surface or in its pores....