Effect of Tourmaline Addition on the Anti-Poisoning Performance of MnCeOx@TiO2 Catalyst for Low-Temperature Selective Catalytic Reduction of NOx

In view of the flue gas characteristics of cement kilns in China, the development of low-temperature denitrification catalysts with excellent anti-poisoning performance has important theoretical and practical significance. In this work, a series of MnCeOx@TiO2 and tourmaline-containing MnCeOx@TiO2-T catalysts was prepared using a chemical pre-deposition method. It was found that the MnCeOx@TiO2-T2 catalyst (containing 2% tourmaline) exhibited the best low-temperature NH3-selective catalytic reduction (NH3-SCR) performance, yielding 100% NOx conversion at 110 °C and above. When 100-300 ppm SO2 and 10 vol.% H2O were introduced to the reaction, the NOx conversion of the MnCeOx@TiO2-T2 catalyst was still higher than 90% at 170 °C, indicating good anti-poisoning performance. The addition of appropriate amounts of tourmaline can not only preferably expose the active {001} facets of TiO2 but also introduce the acidic SiO2 and Al2O3 components and increase the content of Mn4+ and Oα on the surface of the catalyst, all of which contribute to the enhancement of reaction activity of NH3-SCR and anti-poisoning performance. However, excess amounts of tourmaline led to the formation of dense surface of catalysts that suppressed the exposure of catalytic active sites, giving rise to the decrease in catalytic activity and anti-poisoning capability. Through an in situ DRIFTS study, it was found that the addition of appropriate amounts of tourmaline increased the number of Brønsted acid sites on the catalyst surface, which suppressed the adsorption of SO2 and thus inhibited the deposition of NH4HSO4 and (NH4)2HSO4 on the surface of the catalyst, thereby improving the NH3-SCR performance and anti-poisoning ability of the catalyst.

Modulating Ni/Ce Ratio in NiyCe100-yOx Electrocatalysts for Enhanced Water Oxidation

Oxygen evolution reaction (OER) is the key reaction for water splitting, which is used for hydrogen production. Oxygen vacancy engineering is an effective method to tune the OER performance, but the direct relationship between the concentration of oxygen vacancy and OER activity is not well understood. Herein, a series of Ni_yCe_100−yO_x with different concentration of oxygen vacancies were successfully synthesized. The larger concentration of oxygen vacancies in Ni₇₅Ce₂₅O_x and Ni₅₀Ce₅₀O_x result in their lower Tafel slopes, small mass-transfer resistance, and larger electrochemical surface areas of the catalysts, which account for the higher OER activities for these two catalysts. Moreover, with a fixed current density of 10 mA/cm², the potential remains stable at 1.57 V for more than 100 h, indicating the long-term stability of the Ni₇₅Ce₂₅O_x catalyst.

Study on the simultaneous reduction of diesel engine soot and NO with nano-CeO2 catalysts

Nano-CeO₂ catalysts simultaneously reduce diesel soot and nitric oxide on a catalytic activity evaluation platform.

Modification of MnCo2Ox catalysts by NbOx for low temperature selective catalytic reduction of NO with NH3

Among the NbOx modified MnCo₂Ox catalysts by co-precipitation, MnCo₂Nb_0.5Ox presented high activity, N₂ selectivity and H₂O resistance for NH₃-SCR reaction at low temperatures.