Tailoring Catalytic Properties of Meso-/Microporous Layered Zeolites By Atomic Layer Deposition

The hierarchical meso-/microporous lamellar zeolites consist of a zeolitic layer structure, with microporosity and mesoporosity within the layers and between the layers, respectively. The surface exposed active sites in layered MWW and MFI zeolites are comparable to those in micropores, and thus, they are important or dominant contributor to the catalytic properties. A modification of surface structures of layered zeolites will create opportunities for endowing these materials with new structural and functional properties. In this talk, the atomic layer deposition technique has been employed to deposit alumina and silica materials, respectively, to tune the surface environment and catalytic behavior of acid sites in layered MWW and MFI zeolites. The physicochemical, acidic and catalytic properties of the resultant zeolites have been investigated using a variety of characterization methods. Catalytic activity and selectivity changes were rationalized in terms of changes in two catalyst descriptors: the surface acid site concentration and distribution and the strength of these acid sites upon surface treatment of these layered zeolite materials.