# 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
#### 7.4.2 Hydroracking  
Hydrocracking is a pivotal process in the petroleum refining industry designed to upgrade heavy oil fractions into lighter, more valuable products [206]. This process involves breaking down large, complex hydrocarbon molecules into simpler ones by reacting them with hydrogen in the presence of a catalyst (Figure 16). Hydrocracking operates under high pressure (typically 1000 to 3000 psi) and elevated temperatures (400 to 450 \({}^{\circ}\)C), ensuring the effective conversion of feedstocks into desirable outputs, such as gasoline, kerosene, diesel, and jet fuel [207]. The bifunctional catalysts used in hydrocracking possess both acidic and metallic sites, enabling simultaneous hydrogenation and cracking reactions. In the context of hydrocracking, kaolin-supported catalysts have shown promising results in terms of product selectivity and yield. These characteristics of kaolin enhance the dispersion of active metal sites, improving the overall catalytic performance. Additionally, kaolin's ability to retain its structure under the harsh conditions of hydrocracking makes it a cost-effective alternative to conventional supports like alumina and silica. The incorporation of kaolin can also influence the acidity of the catalyst, which is a critical  
Figure 16: Schematic representation of the hydrocracking catalytic reaction in industry. Figure adapted from [PERSON] et al. (2019) [207] and [PERSON] et al. (2022) [208]. Reproduced with the permission of Elsevier and Springer. factor in determining the pathway of hydrocarbon cracking and the nature of the resulting products. Moreover, the thermal stability of kaolin helps in maintaining catalyst activity over extended periods, reducing the frequency of catalyst regeneration and replacement. A series of studies have explored the utilization of kaolin-based catalysts in hydrocracking processes, revealing significant advancements and diverse applications. In 2014, [PERSON] et al. (2019) developed hydrocracking catalyst support from Indonesian kaolin, converting it into a zeolite Y and amorphous alumina-silica phase. This combination demonstrated promising structural and surface properties, achieving a zeolite NaY purity of 86-88% with a specific surface area of 186 m\({}^{2}\)/g and a total pore volume of 0.107 mL/g. These properties are crucial for effective hydrocracking, providing a solid foundation for subsequent research into kaolin-based catalysts. Building on this foundation, [PERSON] et al. (2019) synthesized hierarchical mesoporous H-ZSM-5 using kaolin clay as a cost-effective alumina source. The resulting catalyst, which was used for the hydrotreatment of jatropha oil, showed high yields of diesel-range hydrocarbons (up to 93% at 375 \({}^{\circ}\)C and 50 bar) and kerosene-range hydrocarbons (37.4% at 425 \({}^{\circ}\)C and 80 bar). The enhanced stability and performance of this catalyst were attributed to its tailored physicochemical properties, demonstrating the potential of kaolin-based materials in renewable oil processing. In 2017, two significant studies further expanded the application of kaolin in hydrocracking. [PERSON] et al. (2011) integrated catalytic cracking and hydrotreating technologies for deoxygenating waste cooking oil, highlighting the superior performance of acid-treated kaolin (ATK) in reducing oxygenate content from 87.6% to 6.6% and hydrogen consumption from 8.8 mol to 2.4 mol per mol of triglyceride. This integrated approach showcased the versatility of kaolin-based catalysts in processing different feedstocks. Concurrently, [PERSON] et al. (2012) optimized the synthesis of zeolite NaY from kaolin, improving yield and hydrocracking conversion from 39.58% to 55.93% by refining aging and crystallization conditions. Their work emphasized the importance of precise control over synthesis parameters to enhance catalyst performance. A 2022 study by [PERSON] et al. (2013) delved into the mass transfer performance of in situ crystallized Y zeolite on kaolin for vacuum gas oil (VGO) hydrocracking.