Synthesis, Characterization And Catalytic Application Of Mesoporous Alumina Templated By Saccharides

In this paper, mesoporous alumina was synthesized using saccharide compounds as templates. The influence of pH value, the amounts of H2O and template, temperature and stirring time was investigated, and the effect of the adding of surfactant was also examined. The products were characterized using X-ray diffraction (XRD), thermal analysis, transmission electron microscopy (TEM), MAS NMR and N2 sorption methods.Mesoporous alumina can be obtained using glucose, sucrose, starch andβ-cyclodextrin as structure-directing templates, and the molecular size of the templates has a great effect on the physical properties of products, and the templating formation mechanism was tentatively postulated.The properties of products were influenced by the initial pH value of the system, but no obvious trend was found; Surface areas, pore volumes and pore diameters increased with the increase of temperature and the amount of H2O or glucose, and then kept stable. But the properties of products were hardly affected by stirring time.The adding of different kinds of surfactants to the system has a significant influence on the properties of products, which indicated that surfactant and glucose interact with each other. The pore size and distribution of product were increased after the addition of surfactant. Mesoporous alumina with double-size pore distribution could be produced after the addition of nonionic surfactant (P123), at the same time, the pore volume of product could also be increased sharply. The bi-templating mechanismof glucose and P123 and synergetic enwrapping templating mechanism of glucose and ionic surfactants were proposed.Mesoporous alumina can be prepared using Al(NO3)3 and'acid-base pair'aluminum species as aluminum source in the presence of saccharide compounds. For Al(NO3)3 as aluminum source, the molecular size of templates and pH value play an important part in the properties of products. For'acid-base pair'aluminum species as aluminum source, the ratio of acid and base aluminum species plays a great role in the properties of product.Mesoporous Ni/Al2O3 and Ni/ZrO2/Al2O3 catalysts with high surface areas were prepared using glucose as template. XRD and TEM results showed that nickel phase was uniformly dispersed on the support. These catalysts were also characterized by nitrogen adsorption-desorption, UV-vis specrtra and TPR. These catalysts exhibited good activity and marked stability in methane dry reforming.