Zhaoxia Ma

Selective catalytic reduction of NO by NH3 over CuO–CeO2 in the presence of SO2

SO2-induced deactivation of selective catalytic reduction of NO over CuO–CeO2 was studied. In the case of reaction under low O2 concentration of 1.0 vol%, SO2 severely deactivated the catalyst at 240 °C with a surface S atomic concentration as low as 1.34%. However, the deactivated catalyst could be reactivated during online NO reduction under 5.0 vol% O2 without decreasing the surface S concentration of the catalyst, which could be attributed to the involvement of NO2 in the reactions. NO2 could promote the NO removal through three reaction routes: fast SCR reaction, reaction between NO2 and NH3, and reaction between NO2 and NH4+. Especially under conditions of 10% O2, the reaction between NO2 and NH3/NH4+ induced the formation of extra NHX<3 species which promoted the decomposition of surface-deposited sulfate to SO2 with the assistance of Ce2O3, further suppressed the accumulation of sulfate on the catalyst surface, and finally suppressed the SO2-induced catalyst deactivation.

Influence of hexagonal boron nitride on the selective catalytic reduction of NO with NH3 over CuOX/TiO2

Hexagonal boron nitride (hBN) was used as a CuOX/TiO2 catalyst carrier and its effect on NO reduction with NH3 was studied. After hBN was treated with concentrated HNO3, CuOX/TiO2 nanoparticles were dispersed well onto hBN, and the addition of hBN was found to promote NO oxidation, while at the same time suppress NH3 oxidation to NO, and thus promoted the selective catalytic reduction of NO at reaction temperatures between 150 to 350 °C, and a high de-NOX efficiency of 90.6% was achieved at 275 °C. Our study indicates that hBN is a promising catalyst promoter and carrier with excellent stability compared to carbonaceous materials.

Low temperature chlorobenzene catalytic oxidation over MnOx/CNTs with the assistance of ozone

Manganese oxide supported on carbon nanotubes (MnOx/CNTs) were prepared by an impregnation method and their catalytic oxidation performances of chlorobenzene (CB) with the assistance of ozone were investigated. The experimental results indicated a synergistic effect between the MnOx/CNTs catalyst and ozone promotion for CB destruction, which promoted CB oxidation at temperatures between 80 °C and 280 °C. Especially at temperatures below 120 °C, both CB conversion and CO2 selectivity above 95% were achieved with an apparent activation energy of 15.0 kJ mol−1. Moreover, MnOx/CNTs showed good stability and resistance to chlorine poisoning, which was demonstrated by stable catalytic activity for a long-term CB catalytic oxidation with 2300 ppm ozone up to 240 h.

Hierarchical Wall Formation of Titanium Oxide Nanotube Arrays Using Anodic Oxidation

Hydrolytic reaction of TiF 62- induces in situ titanium dioxide (TiO2) nanorings deposition during a TiO2 nanotube array (TONA) preparation by electrochemical anodization. This deposition leads to a reduction of the electric field and the current density beneath the TiO2 nanorings, thus inducing tube wall separation, and results in the formation of a tubular TONA structure. The TiF 62- hydrolytic reaction can also be used to modify the morphology of TONA, which leads to a convenient route to fabricate the novel structures of TONAs for possible new applications.