The treatment of phenolic-containing wastewater has received increased attention in recent years. In this study, the N-doped porous carbons were prepared from lignite with tripolycyanamide as the N source, and their phenol adsorption behaviors were investigated. Results clearly showed that the addition of tripolycyanamide largely improved the surface area, micropore volume, N content and thus the phenol adsorption capacity of lignite-based carbons. The N-doped sample prepared at 700 °C showed a surface area of 1630 m²/g and a phenol adsorption capacity as high as 182.4 mg/g at 20 °C, which were 2.0 and 1.6 times that of the lignite-based carbon without N-doping. Pseudo-second order and Freundlich adsorption isotherm models could better explain the phenol adsorption behaviors over lignite-based N-doped porous carbon. Theoretical calculations demonstrated that phenol adsorption energies over graphitic-N (−72 kJ/mol) and pyrrolic-N (−74 kJ/mol) groups were slightly lower than that over the N-free graphite layer (−71 kJ/mol), supporting that these N-containing groups contribute to enhance the phenol adsorption capacity. The adsorption mechanism of phenol over porous carbon might be interpreted by the π–π dispersion interactions between aromatic-ring and carbon planes, which could be enhanced by N-doping through increasing π electron densities in the carbon plane.

Baeyer–Villiger oxidation can synthesize a series of esters or lactones that have essential application value but are difficult to be synthesized by other methods. Cycloketones can be oxidized to lactones using molecular oxygen, peroxy acids, or hydrogen peroxide as an oxidant. Hydrogen peroxide is one of the environmental oxidants. Because of the weak oxidation ability of hydrogen peroxide, Bronsted acids and Lewis acids are used as catalysts to activate hydrogen peroxide or the carbonyl of ketones to increase the nucleophilic performance of hydrogen peroxide. The catalytic mechanisms of Bronsted acids and Lewis acids differ in the Baeyer–Villiger oxidation of cyclohexanone with an aqueous solution of hydrogen peroxide as an oxidant.

A serial of Cu₂O/activated carbon (AC) and Cu⁰/AC catalysts were prepared in situ and evaluated in methanol oxidative carbonylation to clarify the mechanistic differences between Cu₂O and Cu⁰ active species. It was found that both species are catalytically active, but Cu₂O exhibits significantly higher efficiency than Cu⁰. Feeding sequence studies reveal that, on Cu₂O, co-adsorbed CH₃O and CO react via the L–H mechanism to form CH₃OCO intermediates, a favorable pathway for DMC formation; on Cu⁰, however, CH₃OCO forms via the E–R mechanism between adsorbed CH₃O and gaseous CO, which is less efficient. Moreover, deactivation is mainly due to copper oxidation, which is sequence-dependent but valence-independent. This study highlights Cu₂O as the superior active center and offers fundamental understanding of copper valence-dependent catalysis in methanol oxidative carbonylation.