Polymerization of methyl methacrylate in toluene, at various temperatures with silica gel grade 955 supported \[C\-5Me\-5\]\-2SmMe(THF) was studied. This type of polymerization exhibits several characteristics. The PM...Polymerization of methyl methacrylate in toluene, at various temperatures with silica gel grade 955 supported \[C\-5Me\-5\]\-2SmMe(THF) was studied. This type of polymerization exhibits several characteristics. The PMMA obtained has higher number average molecular weight and wider molecular weight distribution compared with those obtained by solution polymerization with homogeneous catalyst system, although the polymerization activity is lower.展开更多
ZnO/SiO\-2 and ZnO\|SiO\-2 catalysts were prepared by the impregnation and sol\|gel method, respectively. The characterization of the catalysts by XPS and FTIR indicated that much "free" zinc oxide and unrea...ZnO/SiO\-2 and ZnO\|SiO\-2 catalysts were prepared by the impregnation and sol\|gel method, respectively. The characterization of the catalysts by XPS and FTIR indicated that much "free" zinc oxide and unreacted Si\_OH existed on the surface of ZnO/SiO\-2 sample. As for ZnO\|SiO\-2 sol\|gel catalyst, the corresponding phenomena were not observed. The prepared samples were also used as the catalysts for decomposition of 2\|butanol. A high selectivity for dehydrogenation was observed over the supported catalyst. However, a high selectivity for dehydration was shown over the ZnO\|SiO\-2 sol\|gel catalyst. The opposite selectivity for dehydration or dehydrogenation observed over the two kinds of catalysts may be just because of the different surface structures of the catalysts.展开更多
文摘Polymerization of methyl methacrylate in toluene, at various temperatures with silica gel grade 955 supported \[C\-5Me\-5\]\-2SmMe(THF) was studied. This type of polymerization exhibits several characteristics. The PMMA obtained has higher number average molecular weight and wider molecular weight distribution compared with those obtained by solution polymerization with homogeneous catalyst system, although the polymerization activity is lower.
文摘ZnO/SiO\-2 and ZnO\|SiO\-2 catalysts were prepared by the impregnation and sol\|gel method, respectively. The characterization of the catalysts by XPS and FTIR indicated that much "free" zinc oxide and unreacted Si\_OH existed on the surface of ZnO/SiO\-2 sample. As for ZnO\|SiO\-2 sol\|gel catalyst, the corresponding phenomena were not observed. The prepared samples were also used as the catalysts for decomposition of 2\|butanol. A high selectivity for dehydrogenation was observed over the supported catalyst. However, a high selectivity for dehydration was shown over the ZnO\|SiO\-2 sol\|gel catalyst. The opposite selectivity for dehydration or dehydrogenation observed over the two kinds of catalysts may be just because of the different surface structures of the catalysts.
