Yuzhou Deng

Importance of porous structure and synergistic effect on the catalytic oxidation activities over hierarchical Mn–Ni composite oxides

Hierarchically porous manganese–nickel composite oxides (MNCOs) were successfully synthesized by an oxalate route and further applied for catalytic removal of benzene. Among these catalysts, the best one was Mn2Ni1 mixed oxides which exhibited uniform hierarchical lithops-like topography, a rich porous structure and a high surface area of 201.1 m2 g−1. The temperature required for a benzene conversion of 90% over this catalyst was ca. 232 °C under the conditions of a benzene concentration of 1000 ppm in air and a high space velocity of 120000 mL g−1 h−1, which was 54 °C lower than that over the non-porous MNCO particles prepared by a traditional approach. The reaction kinetic study showed that the apparent activation energy (45.2 kJ mol−1) for the total oxidation of benzene over the Mn2Ni1 oxide catalyst was much lower than those (72.4–97.2 kJ mol−1) over other catalysts. With XPS and H2-TPR analyses, the porous MNCOs have a higher content of surface-adsorbed oxygen species and better low-temperature reducibility which can be ascribed to a possible synergetic effect between Mn and Ni ions in the spinel mixed oxides.

Emerging nanostructured materials for the catalytic removal of volatile organic compounds

Abstract The strong growing interest in using catalytic oxidation to remove volatile organic compounds (VOCs), which seriously threaten the health of human being, is rooted in its desirable features such as relative energy savings, low cost, operation safety and environmental friendliness. Within the last decades, the development of manufacturing processes, characterization techniques and testing methods has led to the blossom of research in synthesis and application of various nanostructured materials, which creates great opportunities and also a tremendous challenge to apply these materials for highly efficient catalytic removal of VOCs. We herein will systematically introduce the latest research developments of nanostructured materials for the catalytic degradation of VOCs so as to provide the readers a coherent picture of the field, mainly focusing on noble metals and metal oxides, which are currently two primary types of VOC catalysts. This review will focus on synthesis, fabrication and processing of nanostructured noble metals and metal oxides as well as the fundamentals and technical approaches in catalytic removal of VOCs, providing technical strategies for effectively developing novel nanostructured catalysts with low cost, enhanced activity and high stability for pollutant removal from surrounding environments.

Catalytic Degradation of Benzene over Nanocatalysts containing Cerium and Manganese

Abstract A Ce–Mn composite oxide possessing a rod‐like morphology (with a fixed molar ratio of Ce/Mn=3:7) was synthesized through a hydrothermal method. Mn ions were doped into a CeO2 framework to replace Ce ions, thereby increasing the concentration of oxygen vacancies. The formation energies of O vacancies for the Ce–Mn composite oxide were calculated by applying density functional theory (DFT). The data showed that it was easier to form an O vacancy in the composite. The catalytic behavior of the Ce–Mn composite oxide for benzene degradation was researched in detail, which exhibited a higher activity than the pure phases. Based on this, the Ce–Mn composite oxide was chosen as a supporter to load PdO nanoparticles. The activity was enhanced further compared with that of the supporter alone (for the supporter, the reaction rate R 214 °C=0.68×10−4 mol gcat −1 s−1 and apparent activation energy E a=12.75 kJ mol−1; for the supporting catalyst, R 214 °C=1.46×10−4 mol gcat −1 s−1, E a=10.91 kJ mol−1). The corresponding catalytic mechanism was studied through in situ Raman and FTIR spectroscopy, which indicated that the process of benzene oxidation was related to different types of oxygen species existing at the surface of the catalysts.