# Transforming Petrochemical Processes: Cutting-Edge Advances in Kaolin Catalyst Fabrication
## 7 Kaolin in Petrochemical Catalysis: From Fundamentals to Innovations
### Kaolin-Driven Catalysis in Petrochemical Processes
#### 7.4.1 Fluid Catalytic Cracking (FCC)
Notably, the transformation of zeolite phases during catalyst preparation led to increased mesoporous and stable catalytic performance, which are crucial for modern FCC applications. Building on these foundational studies, research into Y zeolite catalysts highlighted that the unit cell size of Y zeolite plays a critical role in determining the product distribution during catalytic cracking [188]. A model predicting coke formation based on unit cell size was developed, showing that catalysts with larger unit cell sizes produce higher coke, LPG, and dry gas yields, whereas those with smaller sizes favor gasoline production. The exploration of different kaolins, including those from Suzhou, has shown that the chemical and mineralogical properties of kaolin significantly affect catalyst performance [189]. Catalysts derived from Suzhou kaolin, which incorporate approximately 30% NaY zeolite, demonstrated superior activity, attrition resistance, and resistance to metal passivation, outperforming standard commercial catalysts in gasoline and coke selectivity. Further innovations in FCC catalysts involved novel approaches, such as the in situ synthesis of catalysts with high zeolite content, tailored for cracking resid feedstocks [190]. These catalysts showed enhanced pore structures, making large resid molecules more accessible to active sites, thus improving activity and selectivity for resid-containing feedstocks. Subsequent studies introduced advanced composites, such as NaY/kaolin microspheres combined with ZSM-5, to maximize propylene yield [191]. This catalyst exhibited superior meso- and macropores and acid sites, leading to a notable increase in propylene yield compared to traditional catalysts. The development of ZSM-5 from expanded perlite and kaolin [192], as well as \(\beta\)-zeolite synthesized from kaolin [9], showcased improved catalytic performance in FCC napthha aromatization. These zeolites, which are characterized by unique pore systems and tunable crystallinity, offered higher catalytic activity and better product distribution. Evaluations of various components, including Y zeolite, kaolin, and alumina, in the cracking of heavy petroleum residues revealed that Y zeolite significantly increased coke formation, while kaolin and alumina contributed to higher coke yields compared to pure heavy residue [193]. This study highlighted the sensitivity of the TG technique in assessing coke formation during FCC. In another advancement, hydrodesulfurization (HDS) catalysts supported in \(\gamma\)-Al\({}_{2}\)O\({}_{3}\)-MB composites with H-type \(\beta\)-zeolite synthesized from kaolin demonstrated enhanced sulfur reduction capabilities [194]. Additionally, the modification of kaolin-based FCC catalysts with vanadium demonstrated that increased weak Lewis acidity improved sulfur reduction rates [195]. Catalysts with optimal vanadium content achieved substantial reductions in sulfur content, highlighting the effectiveness of this modification. The incorporation of \(\beta\)-zeolite improved the acidity and hydrogenation activity of the catalysts, achieving higher HDS efficiency and deeper sulfur removal compared to traditional supports. Recent innovations have focused on optimizing the synthesis conditions for \(\beta\)-zeolite from kaolin, enhancing the catalyst's performance in the HDS of diesel [196]. By systematically adjusting pretreatment and crystallization conditions, catalysts with \(\beta\)-zeolite content showed improved HDS activities and compliance with ultra-clean diesel specifications. Further advancements included the synthesis of ZSM-5 zeolites on kaolin microspheres using an amine-free system [197]. This method resulted in small-sized ZSM-5 crystallites with high hydrothermal stability and acidity, promoting the production of light olefins during FCC.