Strategies of alloying effect for regulating Pt-based H2-SCR catalytic activity

Enhancement of Pt-O Synergistic Sites through Titanium Vacancies for Low-Temperature Nitrogen Oxide Reduction

Improving the reaction rate of each step is significant for accelerating the multistep reaction of NO reduction by H2. However, simultaneously enhancing the activation of different gaseous reactants using single-atom catalysts remains a challenge to maximize the activity. Herein, we propose a strategy that utilizes titanium-vacancy-regulated electronic properties of single atoms and defective support (Pt1/d-TiO2) to facilitate electron transfer from edge-share O atoms (OTi) to adjacent Pt single atoms. This leads to the formation of low-valence Pt and unsaturated-charge OTi sites, which causes the catalytic reaction to follow a synergistic mechanism. Specifically, experimental and theoretical analyses demonstrate that low-valence Pt sites finely tune the adsorption of H2 molecules, consequently lowering the dissociation energy from 0.15 to as low as 0.01 eV. Moreover, using quasi-in situ spectroscopy, we clearly observe NO molecules being adsorbed on interfacial oxygen sites of a defective support. Then, the bond energy of the N-O bond is weakened through an electron acceptance-donation mechanism between unsaturated-charge OTi sites and NO, thereby facilitating NO activation. The designed single-atom catalysts with synergistic sites exhibit unmatched activity at low temperatures (above 90% NOx conversion at 100 °C), along with higher turnover frequency value (0.74 s-1) and superior stability, making them potentially suitable for industrial applications.

SO2 Resisting Pd-doped Pr1-x Cex MnO3 Perovskites for Efficient Denitration at Low Temperature

H₂ -SCR is served as the promising technology for the controlling of NO_x emission, and the Pd-based derivative catalyst exhibited high NO_x reduction performance. Effectively regulating the electronic configuration of the active component is favorable to the rational optimization of noble Pd. In this work, a series of Pr_1-x Ce_x Mn_1-y Pd_y O₃ @Ni were successfully synthesized and exhibited superior NO conversion efficiency at low temperatures. 92.7 % conversion efficiency was achieved at 200 °C over Pr_0.9 Ce_0.1 Mn_0.9 Pd_0.1 O₃ @Ni in the presence of 4 % O₂ with a GHSV of 32000 h^-1 . Meanwhile, the outstanding performance was obtained in the resistance to SO₂ (200 ppm) and H₂ O (8 %). Deduced from the results of XRD, Raman, XPS, and H₂ -TPR, the modification of d orbit states in palladium was confirmed originating from the incorporation in the B site of Pr_0.9 Ce_0.1 Mn_0.9 Pd_0.1 O₃ . The existence of higher valence (Pd³⁺ and Pd⁴⁺ ) than the bivalence in Pr_0.9 Ce_0.1 Mn_0.9 Pd_0.1 O₃ catalyst was evidenced by XPS analysis. Our research provides a new sight into the H₂ -SCR through the higher utilization of Pd.

Methanol reforming denitration over an integrated bifunctional CuZnOx–X–MnPdOz@Ni catalyst at low temperature

Severe conditions involved in hydrogen storage and transportation limit the practical applications of hydrogen denitration reaction.

Regulating the Coordination of Co sites in Co3 O4 /MnO2 Compounding for Facilitated Oxygen Reduction Reaction

Binary transition metal oxides as a promising oxygen reduction reaction (ORR) catalyst have received significant attention. However, their exact reaction mechanisms are often too complex to be discussed. Herein, novel Co-Mn composites with a well-defined nanostructure were developed for understanding the role of each component. The growth pattern of cobalt oxide and the effects of the coordination environment of Co sites during growth on the overall activity were investigated. Based on experimental and density functional theory studies, it was found that the decaying coordination number directly affected the expression of crystal planes of cobalt oxide, which further had a great influence upon limiting current density of Co-Mn catalysts. The cuboid-Co/Mn catalyst exhibited outstanding limiting current density and showed good stability, related to more highly active (110) planes exposed in Co₃ O₄ . These provided many references for the preparation of related nonprecious catalysts in various domains.