Fabrication of copper supported on hollow silica–alumina composite spheres for catalytic decomposition of nitrous oxide

2019 ◽  
Vol 92 (3) ◽  
pp. 715-722 ◽  
Author(s):  
Tetsuo Umegaki ◽  
Hiromitu Katori ◽  
Kosuke Otake ◽  
Ryutaro Yamamoto ◽  
Yoshiyuki Kojima
Keyword(s):  
Nitrous Oxide ◽  
Catalytic Decomposition ◽  
Hollow Silica ◽  
Silica Alumina ◽  
Alumina Composite ◽  
Decomposition Of Nitrous Oxide

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.

Influence of microwave irradiation on catalytic decomposition of nitrous oxide over Rh/Al2O3 catalyst

2008 ◽  
Vol 9 (14) ◽  
pp. 2303-2307 ◽  
Author(s):  
P. Siva Sankar Reddy ◽  
N. Seshu Babu ◽  
Nayeem Pasha ◽  
N. Lingaiah ◽  
P.S. Sai Prasad
Keyword(s):  
Nitrous Oxide ◽  
Microwave Irradiation ◽  
Catalytic Decomposition ◽  
Al2o3 Catalyst ◽  
Decomposition Of Nitrous Oxide

scholarly journals The catalytic decomposition of nitrous oxide on the surface of gold: a comparison with the homogeneous reaction

1925 ◽  
Vol 108 (745) ◽  
pp. 211-215 ◽  
Keyword(s):  
Nitrous Oxide ◽  
Catalytic Decomposition ◽  
Bimolecular Reaction ◽  
Homogeneous Reaction ◽  
Gaseous Reaction ◽  
Measurable Velocity ◽  
Rare Class ◽  
The Moment ◽  
Kinetics Of ◽  
Decomposition Of Nitrous Oxide

The bimolecular reaction 2N 2 O = 2N 2 + 2N 2 was recently shown to belong to the rather rare class of homogeneous reactions. Decomposition of two molecules of nitrous oxide takes place when a collision of a certain critical degree of violence occurs in the gas. At the moment of collision the two molecules must possess a combined energy of at least 58,000 calories (per 2 gram molecules), and it is probable that most of the collision in which this condition is fulfilled are fruitful. A comparison between the kinetics of this homogeneous decomposition and the corresponding reaction proceeding catalytically at the surface of a solid might be expected to throw light on the mechanism of heterogeneous catalysis. Previous efforts ( loc. cit .) to accelerate the reaction catalytically by the introduction of metals into the bulb in which the homogeneous reaction was going on were fruitless, since the reaction, if any, which took place at the surface of the metal was slow in camparison with the gaseous reaction. This difficulty was overcome by using as a catalyst a fine metal wire heated electrically. This could be raised to a sufficiently high temperature to cause the surface reaction to proceed with measurable velocity while the bulk of the gas was kept cold, thus eliminating the homogeneous reaction. Experiments made with platinum wires in this way were successful. The kinetics of the decomposition of nitrous oxide on the surface of platinum are summarized in the equation – d [N 2 O]/ dt = k [N 2 O]/1 + b [O 2 ]. The reaction is unimolecular, but is complicated by the strong retarding action of the oxygen formed.

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.

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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