Elucidating the role of confinement and shielding effect over zeolite enveloped Ru catalysts for propane low temperature degradation

Thermally Reconstructed Ru/La-Co3O4 Nanosheets with Super Thermal Stability for Catalytic Combustion of Light Hydrocarbons: Induced Surface LaRuO3 Active Phase

Addressing the thermal deactivation of catalysts remains critical for light hydrocarbons (LHs) combustion. This study develops Ru/La-Co3O4 nanosheets combining RuOx and La-doped Co3O4, demonstrating exceptional high-temperature stability. The individual introduction of Ru or La significantly promoted the catalytic activity of Co3O4, but a severe thermal deactivation is still inevitable. Remarkably, the co-decoration of Ru and La brought a prominent resistance to high-temperature, the aged Ru/La-Co3O4 at 750 °C for 4 h presented a better activity than the fresh catalyst and the TC3-90 instead decreased by 11 °C, even only increased by 1 °C after aging 100 h and 15 °C for 200 h. Systematic studies revealed that the co-presence of La and Ru enhanced the resistance to sintering of Co3O4 and promoted the migration of the lattice oxygen, moreover, the high-temperature induced the formation of LaRuO3 perovskite through the reaction of RuOx with the exsolved La from Co3O4. LaRuO3 phase with excellent redox ability and thermal stability presented a superior activity for catalytic combustion of LHs and suppressed the leaching of Ru species in an oxidizing atmosphere at high temperature. This work contributed to the design of catalysts especially Ru based catalysts for the stable elimination of LHs emissions under high temperature conditions.

Recent Advances of the Effect of H2O on VOC Oxidation over Catalysts: Influencing Factors, Inhibition/Promotion Mechanisms, and Water Resistance Strategies

Water vapor is a significant component in real volatile organic compounds (VOCs) exhaust gas and has a considerable impact on the catalytic performance of catalysts for VOC oxidation. Important progress has been made in the reaction mechanisms of H2O and water resistance strategies for VOC oxidation in recent years. Despite advancements in catalytic technology, most catalysts still exhibit low activity under humid conditions, presenting a challenge in reducing the adverse effects of H2O on VOC oxidation. To develop water-resistant catalysts, understanding the mechanistic role of H2O and implementing effective water-resistance strategies with influencing factors are imperative. This Perspective systematically summarizes related research on the impact of H2O on VOC oxidation, drawing from over 390 papers published between 2013 and 2024. Five main influencing factors are proposed to clarify their effects on the role of H2O. Five inhibition/promotion mechanisms of H2O are introduced, elucidating their role in the catalytic oxidation of various VOCs. Additionally, different kinds of water resistance strategies are discussed, including the fabrication of hydrophobic materials, the design of specific structures and morphologies, and the introduction of additional elements for catalyst modification. Finally, scientific challenges and opportunities for enhancing the design of efficient and water-resistant catalysts for practical applications in VOC purification are highlighted.

Weakened Mn-O bond in Mn-Ce catalysts through K doping induced oxygen activation for boosting benzene oxidation at low temperatures

K-doped Mn-Ce solid solution catalysts were synthesized using a combination of coprecipitation and hydrothermal methods, demonstrating excellent performance in benzene oxidation. The catalyst K1Ce5Mn5 exhibited comparable activity to noble metal catalysts, achieving a 90 % benzene conversion at approximately 194 ℃. Durable tests under dry and moist conditions revealed that the catalyst could maintain its activity for 50 h at 218 ℃ and 236 ℃, respectively. Characterization results indicated that the catalyst's enhanced activity resulted from the weakened Mn-O bonding caused by the introduction of K+, facilitating the activation of oxygen and its involvement in the reaction. CeOx, the main crystalline phase of Mn-Ce solid solutions, provided abundant oxygen vacancies for capturing and activating oxygen molecules for the weakened Mn-O structures. This conclusion was further supported by partial density of state analysis from density functional theory computations, revealing that the introduction of K+ weakened the orbital hybridization of Mn3d and O2p. Finally, in situ diffuse reflectance infrared Fourier-transform spectroscopy (in situ DRIFTS) studies on Ce5Mn5 and K1Ce5Mn5 catalysts suggested that the introduction of K+ promoted the conversion of adsorbed benzene. Furthermore, intermediate products were transformed more rapidly for K1Ce5Mn5 compared to Ce5Mn5.