This invention shows a bottom-up synthesis approach to make zeolite crystals comprised of an interconnected network of nanosheets without the use of organics or branching templates. The hierarchical structure contains the micropores of the zeolite structure and intracrystalline meso- and macropores that reduce internal diffusion limitations and enhance external surface area. The synthesis involves seed-assisted crystallization where crystalline zeolite (seed) is added to a synthesis gel. The seeds (partially) dissolve to facilitate the crystallization of nanosheets that branch and form pillared structures (i.e. nanosheets arranged at approximately 90° angles). The zeolite nanosheets comprised of pentasil frameworks (zeolites MFI and MEL). These zeolites have 3-dimensional intersecting medium-sized channels. Our approach eliminates the need for organics to achieve the hierarchical structure (i.e. branching or pillaring of nanosheets). Furthermore, the proposed method leads to high solid product yield and a high concentration of Brønsted acid sites compared to previously reported protocols that rely on the use of organics. The method in the disclosure has been optimized in terms of synthesis time and temperature to improve upon the crystallinity and reducing the percentage of impurity (i.e. formation of different zeolite phase other than MFI or MEL). Our findings reveal that the time of hydrothermal treatment is crucial given that short times can lead to a partially crystalline product while longer times can lead to the nucleation and growth of a different zeolite phase (e.g. mordenite, MOR framework) as an impurity. It has been well known that reduced crystal size leads to better catalytic activity due to reduced effective diffusion length leading to improved access of acid sites to the reactants. These materials also have a high percentage of acid sites that are accessible on external surfaces. To quantify the impact of these physicochemical properties, we tested the materials in two separate catalytic reactions: a liquid-phase reaction that assesses the impact of acid sites on external surfaces and a gas-phase reaction that assesses mass transport limitations. Our findings reveal that these hierarchical zeolites demonstrate unprecedented improvement in catalyst performance with 4-fold lower rates of deactivation, five-fold increases in activity (i.e. turnover number), and nearly 2-fold increases in selectivity.