Researchers in China have developed a strategy for the production of furoin and furil, high-value C₁₀ fuel precursors, by upgrading biomass-based furfural. A paper on their work is published in the journal Fuel.

Yuan et al.

Furfural is known to be one of the promising lignocellulosic biomass-derived platform molecules. Given this, the conversion of furfural to γ-valerolactone, cyclopentanone, furfuryl alcohol, and 2-methyl furan has been widely investigated and achieved encouraging results. Moreover, it is also significant to upgrade furfural to higher energy density fuel precursors within the scope of gasoline fuels (C₅ to C₁₂), kerosene/jet fuels (C₈ to C₁₆), and diesel fuels (C₁₀ to C₂₂) through chain-extension reactions, such as aldol condensation.

Furoin and furil, C₁₀ fuel precursors derived from furfural upgrading, display the promising potential to be converted into long-chain liquid fuels upon hydrodeoxygenation (HDO). Moreover, as high-value-added industrial chemicals, they can also be directly applied to fine chemicals, pharmaceutical synthesis, and luminescent materials. To date, various strategies for the preparation of them from furfural have been developed.

For instance, furoin can be obtained by catalyzing furfural coupling with VB₁, and furil can be produced by further oxidizing furoin with Cu(OAc)₂-NH₄NO₃. However, following the growing trend of green chemistry, VB₁, and heavy metal salt can no longer meet the requirements of green chemistry due to easy deactivation and the challenging treatment of reaction wastewater, respectively. Hence, it is of great significance to develop a high-stability and environment-friendly catalyst for upgrading furfural to C₁₀ fuel precursors.

—Yuan et al.

The team developed a feasible strategy for coupling furfural to furoin and further oxidizing it to furil. Results showed that the surrounding structure of the diimidazolium IL was the key to the furfural coupling, and the furoin yield could increase from 26% to 91% by adjusting the structure of ILs.

Moreover, Ce/TiO₂-ZrO₂ exhibited promising catalytic performance for obtaining furil from furoin with a 97 % yield. Meanwhile, it could be recycled six times with only a 20 % decrease in furil yield. Mechanistic studies revealed that Ti₄ ⁺ conducted the oxidation of furoin, and O_latt played a significant role in electronic transfer between the catalyst and O₂, thus facilitating the oxidation of Ce₃ ⁺ and the cycling of Ti₃ ⁺ /Ti₄ ⁺ .

Resources

• Kun Yuan, Huangxian Zhang, Dan Hou, Suqin Wu, Zhenwei Yuan, Jinzhu Chen, Xiaohua Zhang, Xuliang Nie, Wanming Xiong (2024) “Catalytic production of valuable C₁₀ fuel precursors from biomass-based furfural,” Fuel, Volume 368 doi: 10.1016/j.fuel.2024.131680

The team developed a feasible strategy for coupling furfural to furoin and further oxidizing it to furil. Results showed that the surrounding structure of the diimidazolium IL was the key to the furfural coupling, and the furoin yield could increase from 26% to 91% by adjusting the structure of ILs.

Moreover, Ce/TiO₂-ZrO₂ exhibited promising catalytic performance for obtaining furil from furoin with a 97 % yield. Meanwhile, it could be recycled six times with only a 20 % decrease in furil yield. Mechanistic studies revealed that Ti₄ ⁺ conducted the oxidation of furoin, and O_latt played a significant role in electronic transfer between the catalyst and O₂, thus facilitating the oxidation of Ce₃ ⁺ and the cycling of Ti₃ ⁺ /Ti₄ ⁺ .