Naoki Toyama; Haruki Inoue; Shinobu Ohki; Masataka Tansho; Tadashi Shimizu; Tetsuo Umegaki; Yoshiyuki Kojima
Abstract
In this work, we investigate influence of amount of L(+)-arginine on morphology of hollow silica-alumina composite spheres and their activity for hydrolytic dehydrogenation of ammonia borane. Hollow silica-alumina composite spheres were prepared by polystyrene templates method. In this method, silica-alumina ...
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In this work, we investigate influence of amount of L(+)-arginine on morphology of hollow silica-alumina composite spheres and their activity for hydrolytic dehydrogenation of ammonia borane. Hollow silica-alumina composite spheres were prepared by polystyrene templates method. In this method, silica-alumina composite shell were coated on polystyrene particles via a sol-gel reaction using L(+)-arginine as promoter, and the polystyrene template particles were removed by calcination. From the result of transmission electron microscopy, shell thickness of the hollow spheres prepared amount of L(+)-arginine of 0.0581, 0.1163, 0.2325, and 0.4650 g were 10, 20, 26, and 30 nm, respectively. From the result of nitrogen sorption, average pore size of the hollow spheres prepared amount of L(+)-arginine of 0.0581, 0.1163, 0.2325, and 0.4650 g was 6.2, 4.2, 3.4, and 2.9 nm, respectively. These results indicate that pore size and shell thickness changed into adjusting amount of L(+)-arginine. Activity of the hollow spheres prepared using various amount of L(+)-arginine for hydrolytic dehydrogenation of ammonia borane were compared. The result indicates that amount of hydrogen evolution of all the hollow spheres was almost the same level. On the other hands, hydrogen evolution rate increase with decrease of amount of L(+)-arginine.
Tetsuo Umegaki; Yoshiyuki Kojima; Kohji Omata
Abstract
He present study investigated the effect of silica coating on catalytic activity of copper-zinc oxide based catalyst for methanol synthesis. Silica coated catalysts prepared using ammonia and L(+)-lysine as promoters of silica coating shows almost same specific surface area and pore size distribution ...
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He present study investigated the effect of silica coating on catalytic activity of copper-zinc oxide based catalyst for methanol synthesis. Silica coated catalysts prepared using ammonia and L(+)-lysine as promoters of silica coating shows almost same specific surface area and pore size distribution compared with pristine commercial copper-zinc oxide based catalyst, while silica coated catalyst prepared using L(+)-arginine shows significantly lower specific surface area than the pristine catalyst and its mesopores and macropores disappear. Silica coated using ammonia and L(+)-lysine weakly bonds to the commercial catalyst without loading into pores of the catalyst, while silica using L(+)-arginine strongly bonds to the catalyst with loading into the pores of the catalyst. Reduction temperature of fine copper species of the silica coated catalysts shifts to the higher temperature than that of the pristine catalyst, and shift temperatures of the silica coated samples prepared using ammonia and L(+)-lysine are lower than that of the sample prepared using L(+)-arginine, indicating that strongly bonding silica prevents reduction of fine copper species in the commercial catalyst. Among the silica coated catalysts, the coated catalyst prepared with ammonia shows highest COx conversion, and the catalytic activity increase with the decrease of weight ratios of silica to catalyst.