Layered Heteroatom-Containing Zeolites

Heteroatom-containing zeolites with two-dimensional (2D) lamellar structures are unique, as they provide ultrathin nanosheets as building blocks for constructing zeolitic catalysts with significantly enhanced accessibility of heteroatom-related active sites exposed on external surface and also chemically changeable interlayer spaces for creating additional mesopores or expanding the pores. Thus, in processing the catalytic reactions involving bulky substrate molecules, the layered heteroatom-containing zeolites and the related zeolitic materials are generally superior to traditional 3D ones due to the released diffusion constraints. The heteroatoms can be introduced into zeolite frameworks directly in the synthesizing process of layered precursors or by post-synthesis during/after the fabrication of derivative structures. Different synthetic strategies may affect the content, micro-environment, and the coordination state of heteroatom-related active sites and then the catalytic activity. The existing number and the application of layered heteroatom-containing zeolites are still limited, and further exploration is highly desirable.