Synthesis of hierarchical zeolites for enhanced catalytic cracking performance toward larger hydrocarbon molecules

Zeolites, with their high surface area and strong acidity, play a vital role in diverse industrial applications such as adsorption and catalysis. This work focuses on the synthesis of hierarchical zeolites and their performance in catalytic cracking of bulky hydrocarbons. Hierarchical zeolitic materials were successfully prepared by utilizing leached silica, obtained from dealuminated zeolites, as a precursor to form mesoporous aluminosilicates on the surface of parent zeolites. The confined mesoporous structure was confirmed by N2 adsorption, XRD, and TEM, showing improved porosity and enhanced stability against framework collapse and acid site loss compared with conventional desilication methods. The uniform mesoporosity was attributed to the formation of surfactant-templated micelles during synthesis. For bulky molecules such as 1,3,5-triisopropylbenzene, the hierarchical zeolites exhibited 2.01 times (40.1% to 80.8%) higher conversion rate in the decomposition. Because of the enhanced cracking performance due to the accessibility of external acid sites generated within the mesopores. These zeolites also retained a substantial number of acid sites for cracking smaller molecules such as n-dodecane, offering a distinct advantage over alkali-treated zeolites. In addition, they displayed lower coke selectivity, attributed to facilitated diffusion of coke precursors through the mesopore network. These findings highlight the potential of hierarchical zeolites to improve process efficiency and overall value in industrial catalytic applications.