Facile synthesis of nanosized La/ZrO2 catalysts for ketonization of free fatty acid and biomass feedstocks

Various synthesis methods such as deep-deposition-ultrasonication (DPU), co-precipitation-ultrasonication (CPU), deposition-precipitation (DP), co-precipitation (CP) and wet-impregnation (IMP) have been reported for the preparation of lanthanum-modified zirconia (La/ZrO2) catalysts. The acoustic cavitational effect by the DPU method decreased the particles size and enlarged the pores of the La/ZrO2 catalysts. Besides, the La ions well-interacted with the ZrO2 in each catalyst, thus, all the La/ZrO2 catalysts have a great potential to be employed in ketonization reaction. It had found that both DP and DPU methods exhibited smaller catalyst particles than that of the CP, CPU and IMP methods, in which 15 - 20 nm for the La/ZrO2-DPU and 28 - 56 nm for the La/ZrO2-DP. Even though the ultrasonication helped to reduce the particle size notably, adversely the small particles tend to aggregated. Meanwhile, larger nanoparticles can be prevented particle aggregation leading to higher dispersion for the La/ZrO2-DP as compared to the La/ZrO2-DPU. All the catalysts were tested in ketonization of palmitic and lauric acids, showing the La/ZrO2-DP exhibited the best catalyst with free fatty acid (FFA) conversion similar to 80% and 51% of ketone selectivity. In addition, the 10 wt.% of La dosage gave the optimum concentration for the maximum ketonization activity. The La/ZrO2-DP catalyst also promising for the ketonization of real feedstocks such as palm kernel oil (PKO) and palm fatty acid distillate (PFAD) into their ketone species. (C) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

Various synthesis methods have been reported for the preparation of lanthanum-modified zirconia (La/ZrO2) catalysts, with deep-deposition-ultrasonication (DPU) and deposition-precipitation (DP) methods yielding smaller particles compared to other methods. The La/ZrO2-DP catalyst exhibited the best performance in ketonization reactions, with high conversion rates and selectivity for fatty acids.