Effect of Mesporosity for Hierarchical Zeolite Y by Post Synthesis Modification on catalytic cracking of vacuum gas oil (VGO)

Mesoporous hierarchical zeolites were synthesized from pure Y zeolite with a low Si/Al ratio using post-synthesis sequential dealumination and desilication processes. The research examined the impact of ethylenediaminetetraacetic acid (EDTA) and oxalic acid (OX) as chelating agents throughout different dealumination durations (1, 3, and 6 hours) in the dealumination process. The acid-treated zeolite underwent desilication with sodium hydroxide (NaOH) for 0.5 hours. In contrast, the treatment of the parent zeolite with 0.11 M OX acid at 100 ºC prior to 0.2 M NaOH at 65 ºC shown enhanced efficacy in augmenting mesoporosity. For example, utilizing the EDTA – NaOH method resulted in a maximum mesopore volume (Vmeso) of 0.125 m³/g and a specific exterior surface area (Sexternal) of 58 m²/g after 3 hours, whereas the OX – NaOH method exhibited values above 0.20 m³/g and 116 m²/g under identical conditions. Moreover, results comparable to those acquired from the subsequent path were also achieved after just 1 hour and 0.5 hours. The mesoporous zeolites synthesized using OX acid exhibited greater stability, even post-calcination at 550 ºC for 2 hours. Consequently, the implementation of the OX-NaOH scenario can diminish treatment duration, provide an energy-efficient methodology, and yield thermally stable mesoporous zeolites for fluid catalytic cracking. The reaction was conducted in a batch system, yielding about 41.14 vol% gasoline with the modified zeolite (DSY-OX3) at a reaction temperature of 420°C, compared to just 18.4 vol% gasoline yield with the non-modified catalyst. Consequently, the commercialization of the OX-NaOH route can reduce treatment duration and energy usage, yielding a thermally stable mesoporous catalyst for the cracking reactions of heavy oils.