scholarly journals Influence of Morphology of Silica-Alumina Composites on Their Activity for Hydrolytic Dehydrogenation of Ammonia Borane

2016 ◽  
Vol 95 (6) ◽  
pp. 480-486 ◽  
Author(s):  
Naoki TOYAMA ◽  
Shinobu OHKI ◽  
Masataka TANSHO ◽  
Tadashi SHIMIZU ◽  
Tetsuo UMEGAKI ◽  
...  
Keyword(s):  
Ammonia Borane ◽  
Silica Alumina ◽  
Alumina Composites

Fabrication of Hollow Silica-Alumina Composite Spheres Using L(+)-Arginine and their Catalytic Performance for Hydrolytic Dehydrogenation of Ammonia Borane

2014 ◽  
Vol 617 ◽  
pp. 170-173
Author(s):  
Tetsuo Umegaki ◽  
Shunsuke Imamura ◽  
Naoki Toyama ◽  
Qiang Xu ◽  
Yoshiyuki Kojima
Keyword(s):  
High Activity ◽  
Sol Gel ◽  
Hollow Spheres ◽  
Hollow Structure ◽  
Ammonia Borane ◽  
Catalytic Performance ◽  
Hollow Silica ◽  
Silica Alumina ◽  
Alumina Composite ◽  
Composite Walls

The present study reports a facile and effective approach for fabrication of hollow silica-alumina composite spheres. In this approach, silica-alumina composite walls were coated on polystyrene template by the sol-gel method using L(+)-arginine as a promoter for the reaction followed by calcination procedure. Using L(+)-arginine as a promoter of coating process, homogeneous hollow silica-alumina composite spheres are obtained and the wall thickness is larger than that of the hollow spheres prepared with ammonia. The hollow spheres shows high activity for hydrolytic dehydrogenation of ammonia borane compared with spherical silica-alumina composite particles without hollow structure, the hollow spheres prepared with ammonia, and conventional H-BEA zeolite. The results indicate that hollow structure plays important role to show high activity.

The influence of the pore structure of hollow silica–alumina composite spheres on their activity for hydrolytic dehydrogenation of ammonia borane

2017 ◽  
Vol 4 (9) ◽  
pp. 1568-1574 ◽  
Author(s):  
Tetsuo Umegaki ◽  
Ryota Ogawa ◽  
Naoki Toyama ◽  
Shinobu Ohki ◽  
Masataka Tansho ◽  
...  
Keyword(s):  
Pore Structure ◽  
High Activity ◽  
Ammonia Borane ◽  
Hollow Silica ◽  
Silica Alumina ◽  
Alumina Composite ◽  
Hydrolysis Of

Hollow silica–alumina composite spheres with a homogeneous pore structure showed unexpected high activity for hydrolysis of ammonia borane.

One-step synthesis of three-dimensionally ordered macro–mesoporous silica–alumina composites

2014 ◽  
Vol 121 ◽  
pp. 212-214 ◽  
Author(s):  
Long Kou ◽  
Youhe Wang ◽  
Yan Dong ◽  
Dezhi Han ◽  
Bin Ni ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Silica Alumina ◽  
One Step ◽  
Alumina Composites

Control of Shell Thickness of Hollow Silica-Alumina Composite Spheres and their Activity for Hydrolytic Dehydrogenation of Ammonia Borane

2014 ◽  
Vol 617 ◽  
pp. 166-169 ◽  
Author(s):  
Naoki Toyama ◽  
Tetsuo Umegaki ◽  
Qiang Xu ◽  
Yoshiyuki Kojima
Keyword(s):  
Shell Thickness ◽  
Hollow Spheres ◽  
Ammonia Borane ◽  
Acid Sites ◽  
Hollow Silica ◽  
Molar Ratios ◽  
Silica Alumina ◽  
Alumina Composite ◽  
Temperature Programmed ◽  
20 Nm

Herein, we investigated the influence of the shell thickness of hollow silica-alumina composite spheres on their activity for hydrolytic dehydrogenation of ammonia borane (NH3BH3). Silica-alumina composite shells were fabricated by coating on polystyrene (PS) template particles and then completely removing the PS by calcination. Based on the transmission electron microscopy images, the shell thicknesses of the hollow spheres prepared using 5, 10, and 15 g of PS suspensions and coating times of 24.0, 7.0, and 1.5 h were 20, 13, and 5 nm, respectively. The results indicated that the shell thickness of homogeneous hollow spheres was controlled by adjusting the amount of PS suspension and the coating time. In the presence of the hollow spheres with shell thicknesses of 5, 13, and 20 nm, 10.0, 9.5, and 9.0 mL of hydrogen was evolved from aqueous NH3BH3solutions for 13, 12, and 13 min, respectively. The molar ratios of the hydrolytically generated hydrogen to the initial NH3BH3in the presence of the hollow spheres with shell thicknesses of 5, 13, and 20 nm were 2.6, 2.5, and 2.3, respectively. From these results, it can be inferred that the activity for the hydrolytic dehydrogenation of NH3BH3increase with decrease of the shell thickness of the hollow spheres. The result of the temperature-programmed desorption profile of ammonia showed that in the number of amount of acid sites of the hollow spheres increase with decrease of the shell thickness of the hollow spheres. The results indicate the activity depends on the number of acid sites of the hollow spheres.

Influence of alcohol solvents on morphology of hollow silica–alumina composite spheres and their activity for hydrolytic dehydrogenation of ammonia borane

2016 ◽  
Vol 82 (1) ◽  
pp. 92-100 ◽  
Author(s):  
Naoki Toyama ◽  
Shinobu Ohki ◽  
Masataka Tansho ◽  
Tadashi Shimizu ◽  
Tetsuo Umegaki ◽  
...  
Keyword(s):  
Ammonia Borane ◽  
Hollow Silica ◽  
Silica Alumina ◽  
Alumina Composite ◽  
Alcohol Solvents
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