Activity and Stability of Perovskite-Type Oxide LaCoO₃Catalyst in Lignin Catalytic Wet Oxidation to Aromatic Aldehydes Process

Abstract

The perovskite-type oxide catalyst LaCoO3, prepared by the sol−gel method, was tested for catalytic wet oxidation (CWAO) of lignin to aromatic aldehydes. The lignin conversion and yield of each aromatic aldehyde were significantly enhanced by the catalytic process, compared to the noncatalytic process. A mechanism involving the reaction of lignin molecules with adsorbed oxygen surface sites, Co(surf) 3+O2 −, was proposed on the basis of experimental observations, yielding the cycle of Co(surf) 3+ → Co(surf) 2+ → Co(surf) 3+O2 − → Co(surf) 3+. The formation rates of the intermediates quinonemethide and hydroperoxide were the rate-determining steps. The activity and perovskite-type structure of the LaCoO3 catalyst did not undergo any obvious changes after the five successive reactions.

Perovskite-like catalysts LaBO3 (B = Cu, Fe, Mn, Co, Ni) for wet peroxide oxidation of phenol

“…Fe-, Cu-, Mn-, Co-and Ni-containing perovskite-like oxides prepared by various methods were catalytically active in aqueous media to the reactions such as decomposition of hydrogen peroxide [16][17][18]; catalytic destruction of ketopropionic acid with ozone [19]; wet air catalytic oxidation of organic substrates (salicylic acid [20], lignin [21][22][23], stearic acid [24] and phenol [25][26][27]); as well as photocatalytic oxidation of acetic acid using Fe-, Mn-, Co-, Ni-, Cucontaining perovskites supported on cordierite monoliths [28]. There are only two publications devoted to the studies of catalytic properties of perovskite-like oxides in the CWPO.…”

Synthesis of perovskite-based nanocomposites for deNOx catalytic activity

“…[42,43] [45,46] The comparison with the binding energy values depicted in Figure 4 indicates the same binding energy value of the 2p 3/2 peak at 780.5 eV for P2 and P3, which is characteristic of Co in +2 and +3 oxidation states of the CoO and Co 2 O 3 species, respectively, present in both these samples. Whereas in the absence of oxygen in vacuum during calcination, this doping seems to be difficult and a consequent phase separation.…”

Selective Production of Aromatic Aldehydes from Heavy Fraction of Bio-oil via Catalytic Oxidation

“…In the oxidation mechanism, intermediates (1), (2) and (3) are the key intermediates and rate-determining steps, which is similar to the literature. 27 Hence, the improvement of aldehyde yield can be attributed to the [(TPPS 4 )Co=O] +• /Co(TPPS 4 ) redox turnover, which can increase the formation rate of intermediate (2), resulting in an increase in the overall rate of unsaturated side chain of aromatic compounds oxidation.…”