Efficient Selective Oxidation of Aromatic Alkanes by Double Cobalt Active Sites over Oxygen Vacancy‐rich Mesoporous Co₃O₄

Abstract

The development of efficient catalyst for selective oxidation of hydrocarbon to functional compounds remains a challenge. Herein, mesoporous Co 3 O 4 (mCo 3 O 4 -350) showed excellent catalytic activity for selective oxidation of aromatic-alkanes, especially for oxidation of ethylbenzene with a conversion of 42 % and selectivity of 90 % for acetophenone at 120 °C. Notably, mCo 3 O 4 presented a unique catalytic path of direct oxidation of aromatic-alkanes to aromatic ketones rather than the conventional stepwise oxidation to alcohols and then to ketones. Density functional theory calculations revealed that oxygen vacancies in mCo 3 O 4 activate around Co atoms, causing electronic state change from Co 3 + (Oh) !Co 2 + (Oh) . Co 2 + (Oh) has great attraction to ethylbenzene, and weak interaction with O 2 , which provide insufficient O 2 for gradual oxidation of phenylethanol to acetophenone. Combined with high energy barrier for forming phenylethanol, the direct oxidation path from ethylbenzene to acetophenone is kinetically favorable on mCo 3 O 4 , sharply contrasted to non-selective oxidation of ethylbenzene on commercial Co 3 O 4 .

Expediting Ethylbenzene Oxidation via a Bimetallic Cobalt–Manganese Spinel Structure with a Modulated Electronic Environment

“…To sum up, a high AP yield of 69.7% (conversion: 77.9%; selectivity: 89.5%) can be obtained in the presence of 0.07 g of CMO catalyst at 130 °C for 6 h in 20 mL of EB using 0.7 MPa of O 2 . This AP yield value of 69.7% is higher than that of the recent reports using Co- or Mn-based catalysts for the selective oxidation of EB under similar reaction conditions, such as mesoporous Co 3 O 4 (37.8%), CeO 2 /Co 3 O 4 (57.6%), mesoporous Ni–Co mixed oxides (64.9%), MnO x /HTS (25.5%), Mn/N–C/Al 2 O 3 (27.5%), and tremella-like δ-MnO 2 (67.0%) …”

A-site defective La2−xCuO4 perovskite-type oxides for efficient oxidation of cyclohexylbenzene

“…Subsequently, the ˙O 2 − species attacks the α-H atom in adsorbed RH ad , generating ROO˙ radicals. 66 Meanwhile, with the help of ˙O 2 − species, CHB can be polarized and cleaved into CHB tertiary carbon radicals (R˙) and OOH − species, 67 through the hydrogen atom bonded to surface coordination-unsaturated Cu and La ions related to the cyclohexyl tertiary carbon. 68,69 Subsequently, R˙ radicals react with molecular oxygen to form ROO˙ radicals.…”

Surface Oxygen Vacancy-Rich Co3O4 Nanowires as an Effective Catalyst of Luminol–H2O2 Chemiluminescence for Sensitive Immunoassay

“…Cobaltosic oxide (Co 3 O 4 ) is a typical spinel-type oxide and was widely applied in many fields due to its outstanding catalytic properties, cost effectiveness, and eco-friendliness. ,,,− In the present study, Co 3 O 4 nanowires were prepared by a one-step hydrothermal process, and then, the Co 3 O 4 nanowires were simply treated with NaBH 4 to introduce oxygen vacancies. We systematically evaluated the effect of surface oxygen vacancy on activity of Co 3 O 4 nanowires for catalyzing the luminol–H 2 O 2 CL reaction.…”