Characterization of CrOx/Al2O3 catalysts for dichloromethane oxidation

Low Temperature Ozonation of Acetone by Transition Metals Derived Catalysts: Activity and Sulfur/Water Resistance

Different transition metals (Cr/Fe/Mn/Co) derived catalysts supported on γ-Al2O3 were prepared by the isovolumetric impregnation method for catalytic ozonation of acetone (C3H6O), and their catalytic activities under industrial complex conditions were investigated. Among them, CrOx/γ-Al2O3 catalyst with Cr loading of 1.5%, abbreviated as Cr1.5%, achieved the best activity, benefitting from its larger surface area, larger proportion of Cr6+/Cr, more chemically desorbed oxygen species Oβ, appropriate acidity, and superiority of low-temperature reducibility. Simulated industrial conditions were used to investigate the applicability of Cr1.5% catalysts for catalytic ozonation of acetone. Results illustrated that the optimum temperature range was 120–140 °C, with molar ratio O3/C3H6O > 6. Different C3H6O initial concentrations had less effect over the activity of Cr1.5% catalysts, with little residual ozone, confirming the applicability of Cr1.5% catalysts in industrial application. The effects of sulfur/water vapor on catalytic activity were also investigated, and satisfactory resistance to sulfur or water vapor individually was obtained. Finally, in-situ DRIFTS measurement was carried out, to explore and illustrate mechanisms of acetone catalytic ozonation pathways and sulfur/water poisoning.

Co–Cr bimetallic oxides derived from layered double hydroxides with high catalytic performance for chlorinated aromatics oxidation

Co–Cr bimetallic oxides with different Co/Cr molar ratios were prepared through a layered double hydroxide (LDH)-derived method.

Amorphous Cr-doped g-C3N4 as an efficient catalyst for the direct hydroxylation of benzene to phenol

The intrinsic correlations between catalyst structure and catalytic performance at different calcination temperatures were studied.

Promoting effect of Nb doping on catalytic performance for deep oxidation of 1, 2-dichloroethane over (Ce,Cr)xO2-Nb2O5 catalysts

A series of Nb-doped (Ce,Cr)_xO₂-Nb₂O₅ mixed oxides with varying (Ce,Cr)_xO_2/Nb₂O₅ mass ratio were prepared by a co-precipitation method and evaluated for the catalytic performance of eliminating 1,2-dichloroethane (DCE). The results indicate that there exists a strong synergistic effect between acid sites and redox species in (Ce,Cr)_xO₂-Nb₂O₅ improving the catalytic activity for DCE oxidation. Appropriate Nb doping could promote the high dispersion and the interaction of metal oxides in the (Ce,Cr)_xO₂-Nb₂O₅ catalysts, resulting in the formation of more Cr⁶⁺ species with strong oxidizing ability and excellent mobility of oxygen species from bulk to surface to create more active sites for DCE deep oxidation. The (Ce,Cr)_xO₂-Nb₂O₅ catalysts with (Ce,Cr)_xO₂/Nb₂O₅ ratios of 2/1~1/2 exhibit excellent catalytic activity and durability for DCE degradation in dry air as well as benzene or water vapor, and less chlorinated byproduct is produced during the degradation of DCE.

Promotional effect and mechanism study of nonmetal-doped Cr/CexTi1−xO2 for NO oxidation: tuning O2 activation and NO adsorption simultaneously

Nonmetal-doped Cr/Ce_xTi_1−xO₂ was conductive to tune O₂ activation and NO adsorption strength simultaneously. Moreover, the catalytic mechanism was investigated for NO oxidation.

Catalytic low-temperature combustion of dichloromethane over V–Ni/TiO2 catalyst

A plausible pathway for DCM oxidation over V–Ni/TiO₂.

Structure–activity relationship of Cr/Ti-PILC catalysts using a pre-modification method for NO oxidation and their surface species study

Two Cr(vi) species are generated via pre-modification, which play the different roles in the catalytic reaction. That is, oxide state CrO₃ is beneficial to form the redox reaction with Cr₂O₃, and chromate with anionic form is adverse to accumulate SO₂ to improve their resistance.