Insight into Ce Doping Induced Oxygen Vacancies over Ce‐Doped Mno₂ Catalysts for Imine Synthesis

Abstract

of main observation and conclusion The pursuit of modern sustainable chemistry has stimulated the development of innovative catalytic processes that enable chemical transformations to be performed under mild and clean conditions with high efficiency. Here, an amorphous sheet-like MnO2 (Ce-doped MnO2: CMBO) was obtained after Ce doping, which exhibits excellent catalytic performance for the oxidation coupling of alcohol and aniline. Conversion of 99% and a selectivity of 99% could be achieved within 6 h at 60 o C under air atmosphere, and the formation rate of target product was up to 30.2 μmol•h-1 •m-2. Based on a series of characterizations, it was found that the doping of Ce into the MnO2 could increase the concentration of the oxygen vacancies, thus forming abundant active surface oxygen species and favoring the mobility of lattice oxygen, which are the main reasons for the greatly enhanced catalytic performance of CMBO. This work indicates that increasing oxygen vacancy by element doping may serve as a facile and efficient way to enhance catalytic performance of transition metal oxide.

Imine Synthesis by Benzylamine Self-Coupling Catalyzed by Cerium-Doped MnO2 under Mild Conditions

“…The O 1s spectra (Figure 2c) can be deconvoluted into three peaks at around 529.4, 531.9, and 533.4 eV, attributed to lattice oxygen species (O α : O 2− ), adsorbed oxygen species (O β : O 2 − , O − , and OH − ), and adsorbed oxygen in water molecules (O γ : physisorbed, chemisorbed, and structural H 2 O), respectively. 30,31 The lattice oxygen and adsorbed oxygen species are predominant on the surfaces of the CeMn catalysts. CeMn-RO showed significantly more O β (0.42) and O γ (0.22) species compared with CeMn-OH and CeMn-H.…”

Visible‐Light Photocatalytic and Photo‐bactericidal Activity of Ni‐CuWO4/OTiO2 Composite†

“…The selective photooxidation coupling of benzylamine to BPMI provides an important approach for industry, particularly for several pharmaceutical, agricultural and biological key compounds or intermediates. [ 4‐8 ] Specifically, the synthesis of BPMI needs to condense a primary amine with a carbonyl compound. This process involves the use of unstable aldehyde, Lewis acid catalyst, dehydrating agent as well as the prolonged reaction time and the harsh reaction conditions, which restrained the practically application of those processes.…”

Efficient Synthesis of Imines by Oxidative Coupling Catalyzed by Ce‐Mn Oxide Microspheres

“…Aprotic amine‐modified MnO 2 catalysts provided enhanced imine selectivity in the synthesis [8] . Recently, MnO x /CeO 2 materials with morphology such as nanoparticles, [9] nanorods [10] and sheet‐like [11] were described as high performance catalysts for the oxidation of various amines. The presence of Ce could induce the formation of oxygen vacancies, leading to increased oxygen storage ability and active surface oxygen [9–12] .…”

“…Recently, MnO x /CeO 2 materials with morphology such as nanoparticles, [9] nanorods [10] and sheet‐like [11] were described as high performance catalysts for the oxidation of various amines. The presence of Ce could induce the formation of oxygen vacancies, leading to increased oxygen storage ability and active surface oxygen [9–12] . As a result, MnO x /CeO 2 mixed oxides provided superior catalysis to pure manganese oxides.…”

“…The presence of Ce could induce the formation of oxygen vacancies, leading to increased oxygen storage ability and active surface oxygen. [9][10][11][12] As a result, MnO x /CeO 2 mixed oxides provided superior catalysis to pure manganese oxides.…”