# 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
#### 7.4.5 Deoxygenation  
Catalytic deoxygenation processes are pivotal in the petrochemical industry for the conversion of renewable feedstocks into high-value hydrocarbon fuels. These processes, which primarily include hydrodeoxygenation (HDO) and decarboxylation/decarbonylation (DOD/DEC), focus on removing oxygen from organic compounds to enhance fuel quality and energy density. HDO involves the reaction of oxygen-containing compounds with hydrogen to produce water and hydrocarbons, while DOD/DEC eliminates oxygen as carbon dioxide or carbon monoxide. These transformations are essential for upgrading bio-derived oils and fats to meet stringent fuel specifications and improve their overall performance [247]. The efficacy of deoxygenation processes is largely dependent on the catalysts employed, such as nickel (Ni), molybdenum (Mo), or noble metals supported on various materials. Recent advancements demonstrate the significant impact of kaolin-based catalysts on deoxygenation efficiency, showcasing their versatility and effectiveness. In 2019, [PERSON] et al. [200] introduced acid-treated kaolin (ATK) as an effective catalyst for upgrading waste cooking oil (WCO). This catalyst achieved a high deoxygenation efficiency of 93.8% and a yield of 74.4% in organic liquid products (OLPs). Compared to a commercial petroleum catalyst (CC), which reached 90.8% oxygen removal but generated a higher proportion of undesired aromatics, ATK demonstrated superior performance. The effectiveness of ATK was linked to its density of weak Lewis acids, which play a crucial role in the deoxygenation process. Expanding on this, [PERSON] et al. (2021) [248] explored the transformation of Indonesian kaolin into aluminoisilates with varying pore structures using a two-step hydrothermal synthesis. They found that the choice of structure-directing agents (SDAs) significantly influenced the formation of micropores and mesopores. Mesoporous Allocation-41 exhibited superior catalytic activity for deoxygenating bio-oil into green diesel compared to ZSM-5, which was primarily microporous. This study highlighted the benefits of tailoring pore structures to enhance catalytic performance. Further advancements were made by [PERSON] et al. (2021) [249], who investigated metal-supported zeolite catalysts for the deoxygenation of palm fatty acid distillate (PFAD). Their research showed that the combination of NiO and Co\({}_{3}\)O\({}_{4}\) supported on zeolite achieved the highest organic liquid product (OLP) yield of 67.9% at 300 \({}^{\circ}\)C, with hydrocarbon yields reaching 84.8%. This work demonstrated the effectiveness of kaolin-derived zeolite catalysts in converting PFAD into valuable biofuels. In a more recent study, [PERSON] et al. (2023) [250] further optimized hierarchical ZSM-5 structures synthesized from kaolin. By adjusting hydrothermal conditions, they achieved a balance between micro- and mesopores, which greatly improved catalytic performance for deoxygenation reactions. The optimized catalyst demonstrated a 71.6% selectivity toward diesel hydrocarbons, showcasing enhanced efficiency due to improved reactant diffusion within the hierarchical structure. Lastly, [PERSON] et al. (2023) [49] focused on acid-modified kaolin (AMK) for upgrading coal pyrolysis volatiles. Their study showed that AMK catalysts, which were modified using calcination and HCl leaching, improved tar upgrading performance by reducing the oxygen content in tar by 17.92-31.54%. The AMK800 catalyst, with its high specific surface area and Brensted acid sites, was particularly effective in enhancing tar conversion and aromatic generation. Overall, the integration of kaolin-based catalysts into deoxygenation processes represents a significant advancement in the development of efficient and sustainable petrochemical technologies. Their ability to improve catalyst performance while reducing costs and environmental impact underscores their growing importance in the industry.