Tuning effect of amorphous Fe₂O₃on Mn₃O₄for efficient atom-economic synthesis of imines at low temperature: improving [O] transfer cycle of Mn³⁺/Mn²⁺in Mn₃O₄

Abstract

<p>A facile and scaled-up synthesis route to efficient and environmental-friendly metal oxide catalysts with desirable properties is of great practical importance, owing to their excellent performance as heterogeneous catalysts in...</p>

Cerium-Doped Manganese Oxide Catalyst for the Oxidative Coupling Synthesis of Fluorescent 2-Amino-1,9-dimethyl-3H-phenoxazin-3-one Using Atmospheric Oxygen

“…39-1218) and to the tetragonal Hausmannite structure of Mn 3 O 4 (JCPDS No. 24-0734) . No extra peaks of CeO 2 were observed in the pattern of Mn 0.9 Ce 0.1 O y -350, demonstrating the successful doping of the lattice with cerium ions, which was further certified by both Fourier transform infrared (FTIR) and Raman spectroscopy, as displayed in Figures S3 and S4.…”

“…24-0734). 30 No extra peaks of CeO 2 were observed in the pattern of Mn 0.9 Ce 0.1 O y -350, demonstrating the successful doping of the lattice with cerium ions, which was further certified by both Fourier transform infrared (FTIR) and Raman spectroscopy, as displayed in Figures S3 and S4. However, the peaks from Mn 0.9 Ce 0.1 O y -350 become weaker, indicating its relatively poor crystallinity.…”

“…According to the research foundation of our group in aniline oxidation and cerium doping, − herein, we report the development of a new cerium-doped manganese oxide catalyst, which possesses the appropriate oxidation and oxygen activation capacity for the oxidative coupling synthesis of substituted aminophenoxazinones, via the oxidative coupling of 2-aminophenols under an atmosphere of air.…”

Influence of Calcination on Mesoporous Mn1Zr0.5Oy Solid Solution in Oxidative Coupling Catalysis for Benzylideneaniline Formation

“…The conversion goes from 86 % to 100 % and then down to 68 %, and the productivity of imine also follows the similar tendency. The optimum result is obtained over the Mn 1 Zr 0.5 O y catalyst calcined at 400 °C, and an excellent yield (99 %) to imine is acieved under air at 80 °C for 3 h. This result ranks the second position among all the Mn‐based catalysts ever reported, being slightly lower than the best Fe 5 Mn 5 catalyst (6.53 mmol h −1 g −1 ) under exactly the same reaction conditions [12] . Moreover, the used Mn 1 Zr 0.5 O y catalyst after a proper treatment (see experimental details) can keep almost the same activity and selectivity in comparison with the fresh catalyst, which is rationally verified in both the kinetic‐controlled conditions and the optimized conditions (Figure S1).…”

“…Incorporating a second metal to manganese oxide is an effective way to modify its pristine crystal structure, textural parameter, redox ability and amphoteric property [8] . In this context, several bimetallic manganese oxides have been reported as active catalysts for benzylideneaniline formation, such as Cs/MnO X , [9] MnO X /HAP, [10] MnCo 2 O 4 , [11] Fe 5 Mn 5 [12] and MnO X /TiO 2 @SBA‐15 [13] . Nevertheless, the reported catalytic systems still have some obvious shortcomings, such as unsatisfying conversion or selectivity, high reaction temperature and long reaction time, complicated morphology‐controlled synthesis, and requirement of pure O 2 .…”