Perovskite-Type LaCoO₃ as an Efficient and Green Catalyst for Sustainable Partial Oxidation of Cyclohexane

Abstract

Perovskite-type LaCoO3 catalysts were studied for cyclohexane oxidation with molecular oxygen in a solvent-free system. Catalysts with various Lanthanum to Cobalt molar ratios were prepared through a modified citric acid procedure and characterized by different techniques. Among all catalysts, the best cyclohexane conversion results (8.3%) with a K/A oil (cyclohexanone and cyclohexanol) selectivity of 90% were obtained over LaCoO3 with a La to Co molar ratio of 1:1. The high catalytic activity on the perovskite-type LaCoO3 catalyst was explored by experimental and theoretical methods. Density functional theory-based calculations clarified the role of La and Co ions in oxygen and cyclohexane adsorption, respectively. The characterization results indicated that a single-phase LaCoO3 perovskite with a dominance of surface Co 3+ species and relatively high concentration of adsorbed oxygen species on the catalyst surface enhances the catalytic performance. This study presents insights into the design of a highly active, cost-effective, and green catalyst for cyclohexane partial oxidation.

Synthesis and characterization of LaCoxNi1‐xO3 perovskites as heterogeneous catalysts for phenolics degradation by persulfate activation

“…The specific surface area (SSA) ranged from 6.3 to 11.9 m 2 g −1 , while the average pore diameter ranged from 13.3 nm to 20 nm (Table 1). These values are considered rather typical and characteristic for perovskite materials prepared by different sol–gel methods 29,35 …”

“…These values are considered rather typical and characteristic for perovskite materials prepared by different solgel methods. 29,35 The X-ray fluorescence technique was used to determine the chemical composition of perovskite catalysts and verify the theoretically expected molecular ratio of nickel: cobalt cations (Ni:Co). Figure 2 shows the representative spectrum for the LaCo 0.25-Ni 0.75 O 3 perovskite sample.…”

Selective Oxidation of Cyclohexane to Cyclohexanol/Cyclohexanone by Surface Peroxo Species on Cu-Mesoporous TiO2

“…Selective oxidation of C­(sp 3 )–H bonds in alkanes to produce high-value-added products remains one of the biggest challenges for chemical engineers . Among those reactions, selective oxidation of cyclohexane (CHA) to commercial KA–oil, including cyclohexanol (CHAol) and cyclohexanone (CHAone), which is an important precursor for the fabrication of nylon-6 and nylon-66 polymers, has aroused tremendous interest. , In the industrial production of KA–oil by O 2 , the conversion of CHA is always controlled to be below 5% to prevent its over-oxidation, and the selectivity maintains ca . 80% when cobalt salts are used as the catalysts .…”

“… The obtained CyOO • or CHHP then undergoes dismutation to CHAone and CHAol (eq ). However, the oxidizing • OH inevitably disrupts the C–C bond, which then triggers overoxidation of CHA to cyclohexanedione and epoxycyclohexane and eventually to carboxylic acid, ,, thus decreasing the oxidation selectivity of CHA. In addition, the high molar ratio of H 2 O 2 /CHA (always >2.0) is required due to the short life of • OH. , Till now, the mechanisms involved in the oxidation of CHA by H 2 O 2 are still under debate.…”

Constructing Defective Co3V2O8 Hexagonal Prism for Solvent-free Selective Oxidation of Cyclohexane: Strategy of Ionic Liquid Mediation

“…A typical example is that of the selective oxidation of cyclohexane to KA oil, in which the corresponding products are the crucial intermediates for the nylon manufacturing industry. , To obtain a higher KA oil selectivity (>80%) in the traditional industry, the cyclohexane conversion was commonly limited to approximately 5% to reduce the formation of excessive oxidation byproducts . Therefore, many research contributions have been devoted to overcoming the trade-off effect between activity and selectivity in the aerobic oxidation of cyclohexane, such as mixed metal oxides (MMOs), carbon materials, zeolite-based catalysts, porphyrinic compounds, and metal–organic framework-based catalysts. − MMOs exhibited enormous potential due to their excellent electronic transmission capability and redox ability, especially defective MMOs, which exhibit higher redox and catalytic activity in cyclohexane selective oxidation . Zhang et al designed and synthesized a Ce 0.5 Mn 0.5 O x solid solution with rich surface active oxygen species, which performed excellent catalytic activity (17.7% conversion and 81% KA oil selectivity) in the oxidation of cyclohexane under acetonitrile mediation .…”