Improving the oxidation resistance of HfB2-SiC coatings on carbon/carbon composites by CeO2 doping

CeO2 doped Al2O3 composite ceramic coatings fabricated on γ–TiAl alloys via cathodic plasma electrolytic deposition

Understanding the formation and inhibition of more toxic polychlorinated byproducts from the catalytic oxidation elimination of chlorinated volatile organic compounds (Cl-VOCs) and unveiling efficient strategies have been essential and challenging. Here, RuOx supported on CePO4-doped CeO2 nanosheets (Ru/Pi-CeO2) is designed for boosting catalytic oxidation for the removal of dichloromethane (DCM) as a representative Cl-VOC. The promoted acid strength/number and sintering resistance due to the doping of electron-rich and thermally stable CePO4 are observed along with the undescended redox ability and the exposed multi-active sites, which demonstrates a high activity and durability of DCM oxidation (4000 mg/m3 and 15,000 mL/g·h, stable complete-oxidation at 300 °C), exceptional versatility for different Cl-VOCs, alkanes, aromatics, N-containing VOCs, CO and their multicomponent VOCs, and enhanced thermal stability. The suppression of polychlorinated byproducts is determined over Ru/Pi-CeO2 and oxy-anionic S, V, Mo, Nb, or W doping CeO2, thus the oxy-anionic doping strategy is proposed based on the quenching of the electron-rich oxy-anions on chlorine radicals. Moreover, the simple mechanical mixing with these oxy-anionic salts is also workable even for other catalysts such as Co, Sn, Mn, and noble metal-based catalysts. This work offers further insights into the inhibition of polychlorinated byproducts and contributes to the convenient manufacture of monolithic catalysts with superior chlorine-poisoning resistance for the catalytic oxidation of Cl-VOCs.

Effect of CeO2 doping on high temperature oxidation resistance of YSZ TBCs

The effect of CeO2 doping on structure and catalytic performance of Co3O4 catalyst was studied for low-temperature CO oxidation. The Co3O4 catalyst was prepared by a precipitation method and the CeO2/Co3O4 catalyst was prepared by an impregnation method. Their catalytic performance had been studied with a continuous flowing micro-reactor. The results reveal that the CeO2/Co3O4 catalyst exhibits much better resistance to water vapor poisoning than the Co3O4 catalyst for CO oxidation. The CeO2/Co3O4 catalyst can maintain CO complete conversion at least 8,400 min at 110 °C with 0.6% water vapor in the feed gas, while the Co3O4 catalyst can maintain at 100% for only 100 min. Characterizations with XRD, TEM and TPR suggest that the CeO2/Co3O4 catalyst possesses higher dispersion degree, smaller particles and larger SBET, due to the doping of Ceria, and exists the interaction between CeO2 and Co3O4, which may contribute to the excellent water resistance for low-temperature CO oxidation. Furthermore, the H2 detected in the reactor outlet gas seems to indicate that the water–gas shift reaction is the more direct reason.