Abstract
This work presents a comprehensive investigation into the design, synthesis, characterization, and catalytic evaluation of multicationic LaCo1-xMnxO3±δ (0 ≤ x ≤ 1) and LaNi1-xCuxO3±δ (0 ≤ x ≤ 1) inorganic perovskites in the conversion of bioderived carbonyl-containing compounds into value-added chemicals and biojet fuels. The sol-gel method was specifically employed to synthesize well defined perovskite materials. The prepared perovskites were subsequently characterized using various techniques to discover measurable properties such as porosity, surface area, crystallite sizes, oxygen vacancies, and surface morphology that can be linked to their catalytic performance. The perovskites exhibit sponge-like morphologies and low surface areas for both sets of catalytic systems. For a series of LaCo1-xMnxO3±δ, the perovskites were discovered to have crystallite sizes ranging from 11.8 to 27.8 nm and surface areas ranging from 2.23 to 6.16 m2/g. On the other hand, LaNi1-xCuxO3±δ (0 ≤ x ≤ 1) perovskites exhibited crystallite sizes and surface areas in the range of 10.4 to 35.1 nm and 2.31 to 8.60 m2/g, respectively. Moreover, the partial substitution of Co by Mn and Ni by Cu induced structural distortions, that altered the properties of the resulting material as revealed by differences in quantities of defective sites.
The catalytic activity of the LaCo1-xMnxO3±δ (0 ≤ x ≤ 1) perovskites was evaluated in the conversion of bioderived carbonyl-containing compounds, demonstrating versatile catalysis in one-pot catalytic transfer hydrogenation, esterification, and etherfication reactions. The perovskites resulted in good conversions of up to 97% for aldehydes such as crotonaldehyde, furfural, cinnamaldehyde, and hydrocinnamaldehyde, a maximum of 60% for carboxylic acids such as levulinic acid, and up to 85% for keto substrates like γ-valerolactone. The perovskites also exhibited 100% selectivity towards the desired product for all the substrates except for the transformation of crotonaldehyde which was converted to two products.
Moreover, the catalytic performance of LaNi1-xCuxO3±δ (0 ≤ x ≤ 1) perovskites was assessed in biojet fuel production and exhibited efficient one-pot carbon-carbon coupling and hydrodeoxygenation when methyl benzoate and dodecylmagnesium bromide were reacted together. The perovskites demonstrated excellent activity in attaining biojet fuels, including biogasoline, biokerosene, and biodiesel, achieving maximum conversion of 58.1% and 100% selectivity towards biojet fuel hydrocarbons at relatively low temperatures. This study provides
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valuable insights into the design of effective perovskite catalysts for sustainable biojet fuel synthesis, offering a promising solution for the aviation sector.
For both catalytic systems, the synergy between the metal cations at the B-site and the preferential binding of the substrate to one of the metal cations at the B-site were identified as the main descriptors for high catalytic activity. Lastly, this work contributes to the development of environmentally friendly biojet fuels, aligning with global efforts to reduce greenhouse gas emissions and mitigate climate change.