Zeolite catalysts have found extensive applications in the synthesis of various fine chemicals. However

the micropores of zeolites impose diffusion limitations on bulky molecules

greatly reducing the catalytic efficiency. Herein

we explore an economic and environmentally friendly method for synthesizing hierarchical NaX zeolite that exhibits improved catalytic performance in the Knoevenagel condensation reaction for producing the useful fine chemical 2-cyano-3-phenylacrylate. The synthesis was achieved

via

a low-temperature activation of kaolinite and subsequent

in-situ

transformation strategy without any template or seed. Systematic characterizations reveal that the synthesized NaX zeolite has both intercrystalline and intra-crystalline mesopores

smaller crystal size

and larger external specific surface area compared to commercial NaX zeolite. Detailed mechanism investigations show that the inter-crystalline mesopores are generated by stacking smaller crystals formed from

in-situ

crystallization of the depolymerized kaolinite

and the intra-crystalline mesopores are inherited from the pores in the depolymerized kaolinite. This synthesis strategy provides an energy-saving and effective

way to construct hierarchical zeolites

which may gain wide applications in fine chemical manufacturing.