Catalytic Conversion of α-Pinene to High-Density Fuel Candidates Over Stannic Chloride Molten Salt Hydrates

• Main Authors: Seong-Min Cho, June-Ho Choi, Jong-Hwa Kim, Bonwook Koo, In-Gyu Choi
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Applied Sciences
• Subjects: renewable fuel; high-density fuel; α-pinene dimerization; turpentine; stannic chloride molten salt hydrates
• Online Access: https://www.mdpi.com/2076-3417/10/21/7517

The synthesis of dimeric products from monoterpene hydrocarbons has been studied for the development of renewable high-density fuel. In this regard, the conversion of α-pinene in turpentine over stannic chloride molten salt hydrates (SnCl₄·5H₂O) as a catalyst was investigated, and the reaction products were analyzed with gas chromatography/flame ionization detector/mass spectrometer (GC/FID/MS). Overall, the content of α-pinene in a reaction mixture decreased precipitously with an increasing reaction temperature. Almost 100% of the conversion was shown after 1 h of reaction above 90 °C. From α-pinene, dimeric products (hydrocarbons and alcohols/ethers) were mostly formed and their yield showed a steady increase of up to 61 wt% based on the reaction mixture along with the reaction temperature. This conversion was thought to be promoted by Brønsted acid activity of the catalyst, which resulted from a Lewis acid-base interaction between the stannic (Sn^(IV)) center and the coordinated water ligands. As for the unexpected heteroatom-containing products, oxygen and chlorine atoms were originated from the coordinated water and chloride ligands of the catalyst. Based on the results, we constructed not only a plausible catalytic cycle of SnCl₄·5H₂O but also the mechanism of catalyst decomposition.