Controllable Synthesis, Structural Modulation And Catalytic Performance Study Of Novel Porous Materials

In recent years, three dimensionally ordered macroporous (3DOM) materials have aroused great research interest, and become a hotspot in fields of porous materials due to their unique structure and new functionality. Compared with other porous materials,3DOM materials not only possess high specific surface area and large pore volume, but also have tunable pore size, well-defined surface feature, ordered channel network and good penetrability. Hence,3DOM materials show great potentials in applications of catalyst/carrier, photonic crystal, electrode material, and adsorption/desorption etc. Supported noble metal catalysts have attracted much attention in heterogeneous catalysis because of their relatively high catalytic activity. Generally, the catalytic activity of supported noble metal catalysts is tightly related to the composition and structure of catalyst supports. Therefore, the combination of 3DOM materials with supported noble metal catalyst may result in novel catalysts with excellent catalytic functionality.In this paper, a series of 3DOM CeO2 and Ce02-MOx (M refers to Co,Mn,Ni,Fe,Cu,Cr,Ti and Mo) were synthesized by employing colloidal crystal template method. By using 3DOM CeO2 and Ce02-MOx as catalyst supports,3DOM Au/CeO2 and Au/Ce02-MOx were also fabricated via a bubble-assisted deposition-precipitation method. The catalytic oxidation of formaldehyde over 3DOM Au/CeO2 and Au/Ce02-MOx catalysts were systematically investigated. The catalytic intermediates, surface specimens, surface compositions and valences of 3DOM Au/CeO2 and Au/Ce02-MOx were deeply studied. The mechanism of catalytic oxidation of formaldehyde over 3DOM Au/CeO2 and Au/Ce02-MOx catalysts was proposed.In the first chapter, the classification and application of porous materials were firstly introduced, and then the preparation of macroporous materials, the application of 3DOM catalytic materials and the research status of formaldehyde catalytic oxidation were reviewed.In the second charpter, the polystyrene (PS) colloidal microspheres and [P(St-co-MAA)] colloidal microspheres with the average diameter were prepared by using a free emulsion polymerization method. The PS and [P(St-co-MAA)] colloidal microspheres were assembled into well-defined three dimensionally ordered colloidal crystal templates via a centrifugation-precipitation method. Then,3DOM CeO2 supports were successfully prepared via a complexion sol-gel method by utilizing colloidal crystals as templates, citric acid and Ce(NO3)3·6H2O as reactant precursors. Finally, novel 3DOM Au/CeO2 catalysts were fabricated through a bubble-assisted deposition-precipitation method. The intermediates, species absorbed on catalyst surface, element compositions and valences of catalyst surface were explored. Base on the studies, the mechanism of formaldehyde catalytic oxidation over 3DOM Au/CeO2 was proposed.In the third charpter,3DOM Ce02-MOx supports were synthesized using a sol-gel and precipitation transforming method with above prepared colloidal crystals as templates. Species and contents of transition metal oxides in the catalysts show great influences on catalytic activity. The catalytic activity could reach the highest by optimizing the ratio of CeO2 and MOX. The 3DOM Au/CeO2-Co3O4 catalyst has highest catalytic activity with the complete catalytic oxidation of formaldehyde around 39℃. Furthermore, the phase structure, pore structure, surface element composition and valence of 3DOM Au/CeO2-Co3O4 catalysts were investigated, which was greatly changed with the change of CO3O4 content. Both microporous and mesoporous structure, lov, reducing capacity, low adsorption/desorption temperature and surface microreactor temperature and two states of Au nanoparticles were exsited two in catalyst. The result demonstrated that there is synergistic effect between CeO2 and CO3O4. This effect can be altered with the capacity of catalyst Additionally, the loading amount of Au nanoparticles and pore diameter of catalyst can influence the catalytic activity. Based on the above studies, a mechanism with the support synergizing and the accelerated mobility of oxygen on the surface of catalyst was proposed. It is beneficial to improv(?) catalytic activity and develop novel catalysts.