Synergistic catalysis by Mn promoted ceria for molecular oxygen assisted epoxidation

Ceria-Based Materials for Thermocatalytic and Photocatalytic Organic Synthesis

“…Mn-doped CeO 2 nanocubes with enriched oxygen vacancies and high surface Mn 3+ percentage also exhibited higher catalytic performance than pure CeO 2 nanocubes for styrene epoxidation with TBHP due to the increased reducibility as well as the formation of oxo-metal species . With optimized Mn-doping content, 10MnCe material with 10 mol % Mn showed the best activity with 80% conversion and >99% selectivity for cyclooctene epoxidation with O 2 as oxidant, which is attributed to the high oxygen mobility, low temperature reducibility, abundant oxygen vacancies, low valent states of manganese and cerium, and the ability to generate reactive oxygen species such as superoxide and singlet oxygen species . To increase the catalytic activity of CeO 2 toward allylic oxidation of cyclohexene, CeO 2 nanospheres with about 6 nm and 0.13 mol % loading were immobilized at the internal graphitic step-edges of graphitized carbon nanofibers (GNF), and the obtained CeO 2 @GNF catalysts exhibited controllable product selectivity in the allylic oxidation of cyclohexene to 2-cyclohexenone, as shown in Figure a–d .…”

“…168 With optimized Mndoping content, 10MnCe material with 10 mol % Mn showed the best activity with 80% conversion and >99% selectivity for cyclooctene epoxidation with O 2 as oxidant, which is attributed to the high oxygen mobility, low temperature reducibility, abundant oxygen vacancies, low valent states of manganese and cerium, and the ability to generate reactive oxygen species such as superoxide and singlet oxygen species. 169 To increase the catalytic activity of CeO 2 toward allylic oxidation of cyclohexene, CeO 2 nanospheres with about 6 nm and 0.13 mol % loading were immobilized at the internal graphitic step-edges of graphitized carbon nanofibers (GNF), and the obtained CeO 2 @GNF catalysts exhibited controllable product selectivity in the allylic oxidation of cyclohexene to 2-cyclohexenone, as shown in Figure 16a−d. 170 The encapsulated CeO 2 with Ce 3+ species acts as the radical initiator while the GNF nanotubes act as a host to stabilize the CeO 2 nanospheres and as an electron reservoir to maintain the balance of Ce 3+ and Ce 4+ centers.…”

Soft synthesis and characterization of goethite-based nanocomposites as promising cyclooctene oxidation catalysts

“…Another expensive catalyst that allowed reaching 85% conversion of cyclooctene with 92% selectivity for epoxide at a lower temperature (e.g., 35 C) is a Co(II) coordinated metal-organic framework. 70 wall of a meso-SiO 2 shell, which allowed reaching 90% conversion at 40 C, 71 manganese doped cerium oxide catalysts, which allowed getting 80% conversion at 100 C, 72 were recently reported as highly active heterogeneous catalysts for cyclooctene epoxidation using isobutyraldehyde and molecular oxygen. The disadvantages of the latter two systems are that the synthesis of Co 3 O 4 encapsulated in meso-SiO 2 shell catalyst is difficult to control.…”

Experimental and theoretical investigation of the tuning of electronic structure in SnO2viaCo doping for enhanced styrene epoxidation catalysis

“…1–6 Styrene oxide (SO), as an important member of the epoxides family, is traditionally synthesized by the non-catalytic chlorohydrination of styrene followed by dehydrochalorination of styrene chlorohydrin with a base, or by the organic peracids based catalytic oxidation of styrene. 7–9 However, these processes suffer from several limitations, such as production of a great amount of toxic waste, severe equipment corrosion, high production cost and difficulty in product separation. To overcome these shortcomings, a feasible strategy is to exploit a greener and simper heterogeneous catalytic system in the presence of environmentally benign oxidants ( e.g.…”