This interface () is used to study the impact of adsorption, and heterogeneous reactions, as a gas or liquid is moving through the interstices of a porous medium. Adsorption and desorption of bulk species onto, or from, the fluid-solid interface can be studied, as well as heterogeneous reactions involving both bulk species and surface species bound to the fluid-solid interface. Volumetric reactions occurring in the pore space can also be included. The interface is the same as the Transport of Concentrated Species interface, but it has a Porous Catalyst node added by default. All other features for transport and reactions in porous media are also always available.

The main feature of the interface is the Porous Catalyst node which adds the governing equations for the mass fractions of all bulk species, and the equations for surface species. It has two subnodes, Fluid and Porous Matrix, which in turn are used to define the physical properties corresponding to each phase, and to prescribe the transport properties. The latter are typically the flow field, and when applicable, the electric field. The Adsorption and Surface Reaction subnodes can be added to implement adsorption/desorption and heterogeneous reactions occurring on the fluid-solid interface.

When this physics interface is added, the following default nodes are also added to the Model Builder — Porous Catalyst, No Flux (the default boundary condition), and Initial Values. Then, from the Physics toolbar, add other nodes that implement, for example, boundary conditions, reaction rate expressions, and species sources. You can also right-click Transport of Concentrated Species in Porous Catalyst to select physics features from the context menu.

The rest of the settings are the same as The Transport of Concentrated Species Interface.