# 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
#### 7.4.7 Alkylation  
Catalytic alkylation is considered a fundamental reaction in the petrochemical sector, playing a crucial role in the production of high-octane gasoline and various chemical intermediates. This process involves the reaction between light olefins, such as propylene or burbene, and isoparaffins, predominantly isobutane, to form alkylates [259]. Alkylates are highly branched hydrocarbons that significantly improve the octane rating of gasoline by enhancing engine performance and reducing harmful emissions. The importance of alkylation stems from its ability to produce high-quality gasoline components. High-octane fuels are essential for modern high-compression engines as they resist knocking, which can cause severe engine damage. By increasing the octane number of gasoline, alkylation helps meet stringent environmental regulations and fuel standards, contributing to cleaner and more efficient combustion engines. Alkylation reactions typically occur in the presence of strong acids, such as sulfuric acid or hydrofluoric acid, which act as catalysts [157]. These acids facilitate the protonation of olefins, forming carbocations that react with isoparaffins to produce the desired alkylates. However, the use of liquid acids poses significant safety and environmental risks, including the handling and disposal of corrosive materials and the potential for toxic releases. To mitigate these issues, the industry has been exploring the use of solid acid catalysts as a safer and more sustainable alternative. Solid acids, including those based on zeolites and other porous materials, offer several advantages over liquid acids. They can be easily separated from reaction mixtures, reducing the risk of contamination and simplifying the catalyst recovery process. Additionally, solid acids can be regenerated and reused, lowering operational costs and minimizing environmental impact. Thus, by modifying kaolin solid clays through acid treatments and other chemical processes, it is possible to enhance their acidity and create materials with high surface areas and suitable pore structures for catalytic applications. While the specific role of kaolin-based catalysts in alkylation processes has been less extensively studied than other solid acids, their potential lies in their abundance, low cost, and environmental benignity. In 2011, [PERSON] et al. [260] investigated the gas-phase alkylation of toluene with isopropanol and its transalkylation with cumene using USY zeolite prepared by spray-dried using kaolin as the filler and a dual-zeolite (DZ) catalyst comprising mordenite and ZSM-5. The study revealed that both catalysts showed comparable cynene yields in toluene isopropylylation, but the DZ catalyst achieved maximum yield at a lower temperature. In cumene-toluene transalkylation, the DZ catalyst exhibited higher cynene selectivity and conversion than the USY catalyst. This indicates that dual-zeolite catalysts can effectively enhance selectivity and conversion rates in alkylation processes. One year later, [PERSON] et al. [261] developed a Y/MCM-41 composite molecular sieve from pretreated kaolin, demonstrating high thermal and hydrothermal stability. The composite showed significant catalytic activity in the alkylation of phenol with tert-butyl alcohol, achieving a phenol conversion of 62.3% and a selectivity of 86.2% to 4-tert-butyl-phenol under optimal conditions. The combination of mesoporous MCM-41 and microporous Y-type molecular sieves in the composite contributed to its effectiveness as a catalyst, showcasing the potential of kaolin-based materials in alkylation reactions. [PERSON] et al. [262], also in 2012, studied a selective BXE ALKCAT zeolite catalyst containing 30% ZSM-5 and kaolinite for the alkylation of benzene with ethylene. The catalyst exhibited high selectivity (85.5%) for ethylbenzene (EB) at a 1:1 benzene-to-ethylene molar ratio at 450 \({}^{\circ}\)C. The selectivity decreased at lower temperatures, indicating a strong dependence of reaction efficiency on temperature and reactant ratio.