Towards Mechanistic Understanding of Liquid‐Phase Cinnamyl Alcohol Oxidation with tert‐Butyl Hydroperoxide over Noble‐Metal‐Free LaCo_1–xFe_xO₃ Perovskites

Abstract

Noble‐metal‐free perovskite oxides are promising and well‐known catalysts for high‐temperature gas‐phase oxidation reactions, but their application in selective oxidation reactions in the liquid phase has rarely been studied. We report the liquid‐phase oxidation of cinnamyl alcohol over spray‐flame synthesized LaCo1–xFexO3 perovskite nanoparticles with tert‐butyl hydroperoxide (TBHP) as the oxidizing agent under mild reaction conditions. The catalysts were characterized by XRD, BET, EDS and elemental analysis. LaCo0.8Fe0.2O3 showed the best catalytic properties indicating a synergistic effect between cobalt and iron. The catalysts were found to be stable against metal leaching as proven by hot filtration, and the observed slight deactivation is presumably due to segregation as determined by EDS. Kinetic studies revealed an apparent activation energy of 63.6 kJ mol−1. Combining kinetic findings with TBHP decomposition as well as control experiments revealed a complex reaction network.

Liquid‐Phase Cyclohexene Oxidation with O2 over Spray‐Flame‐Synthesized La1−xSrxCoO3 Perovskite Nanoparticles

“…Perovskite nanoparticles show promising activities in liquid‐phase oxidation reactions [26b,44] . The insertion of Sr into LaCoO 3 might enhance the catalytic activity because of the formation of oxygen vacancies [45] .…”

Flame-made Particles for Sensors, Catalysis, and Energy Storage Applications

“…The reaction between liquid-organic moieties was catalyzed heterogeneously by the perovskite produced reactive oxygen species for surface kinetic reaction. 98 …”

The Effect of Co Incorporation on the CO Oxidation Activity of LaFe1−xCoxO3 Perovskites

“…Perovskites ABO 3 are exciting materials for oxidation catalysis as they provide considerable flexibility regarding their compositions and the possibility to implement oxygen vacancies with a selective modification of the cationic sublattice [1][2][3]. The potential use of perovskites in catalysis is extensive as they can be employed, e.g., in oxygen reduction [4], oxygen evolution [5], CO and hydrocarbon gas-phase oxidation [6], total oxidation of Volatile Organic Compounds (VOC) [7], or selective oxidation of substrates like benzyl alcohol [8] or cinnamyl alcohol [9]. These materials are accessible through a variety of synthetic approaches, such as ceramic methods [10,11], complexation with, e.g., citric acid followed by thermal decomposition [12,13], freeze-drying [14], spray-flame synthesis [15,16], or coprecipitation at increasing pH [17], decreasing pH [18], with manually adjusted constant pH [19] or automatically controlled constant pH [20].…”