Shanshan Shao,Xinggang Hu,Wenbin Dong,Xiaohua Li,Huiyan Zhang,Rui Xiao,Yixi Cai
Aldol condensation of biomass-derives coupled with hydrogenation is a promising route for the production of renewable aviation fuel. In this study, a bifunctional catalyst was prepared to integrate the aldol condensation of cyclopentanone and hydroprocessing for aviation fuel in one pot. Due to its strong mild-basic sites, Mg–Al–O performed the best with the total yield of dimer and trimer of 80.4%. Nickel was screened out to be favorable for hydrogenation. Considering the unsatisfactory porous structure of Ni/Mg–Al–O, the bifunctional catalyst was prepared with activated carbon (AC) as carrier. With Ni loading of 20 wt%, the maximum yield of targeted alkanes reached 81.1% over Ni/Mg–Al–O/AC. The calcination and reduction temperature in the preparation process were both optimized at 550 °C. In the reusability test, the yield of targeted alkanes reduced to 31.6% in the 5th run. To attenuate the hydration effect, n-pentane was introduced as solvent, and the bifunctional Ni/Mg–Al–O/AC performed stably in 5 runs. By the design of bifunctional catalyst based on the theoretical basis to realize the integration of C–C coupling and hydrogenation in one pot, it will promote the development of aviation fuel from biomass in a more sustainable and green way.
It is a simple, green, and energy-saving way to produce targeted alkanes in the range of jet fuel from biomass-derived carbonyls by aldol condensation and hydrogenation in one pot over the bifunctional catalyst. The catalyst and solvent system played a significant role in this. It was discovered that Ni was preferentially loaded on the region centered on the weak basic sites. The amount of weak and medium basic sites gradually decreased as Ni occupied the region, and the aldol condensation performance was inhibited. The aldol condensation was favored in the aqueous solvent compared with that in the organic solvent. Some condensates presented insoluble in the aqueous solvent, and the hydrogenation performance was weakened, resulting in a poor yield of 48.2% for the targeted alkanes. In order to strike a balance between aldol condensation and hydrogenation in the organic and aqueous solvent, the biphasic solvent system was proposed. The results showed that the total yield of targeted alkanes reached 77.0% with an aqueous and organic solvent ratio of 1:2. The catalytic performance of Ni/Mg-Al-O/AC dropped substantially after 5th reuses, caused by Ni sites coverage due to the formation of boehmite via the hydration of Ni/Mg-Al-O/AC with water. Zr ions replaced Al ions in the bifunctional catalyst, then the yield of the final product achieved 75.6% with Ni/Mg-Zr-O/AC, and it was still maintained at 67.9% after 5th reuses. In this study, the one-pot combination of C-C coupling and hydrogenation was achieved by designing the catalyst and solvent system, promoting biomass-derived jet fuel development more sustainably and simply.
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