2002 Fiscal Year Final Research Report Summary
Elucidation of Catalysis by Molecular Hydrogen-Originated Protonic Acid Site
| Project/Area Number |
13450330
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
触媒・化学プロセス
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
HATTORI Hideshi Hokkaido Univ., Center of Advanced Research of Energy Technology, Prof., エネルギー先端工学研究センター, 教授 (00000844)
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| Co-Investigator(Kenkyū-buntansha) |
SATOU Masaaki Hokkaido Univ., Center of Advanced Research of Energy Technology, Res. Asso., エネルギー先端工学研究センター, 助手 (70261360)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Protonic Acid Site / Rate of Hydrogen Adsorption / Spillover / Solid Acid Catalyst / Alkane Isomerization / Zirconia |
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| Research Abstract |
The research aims at developing the new concept of "Molecular hydrogen-originated protonic acid site" and elucidating the catalytic features caused by the surface protons formed from molecular hydrogen.
To elucidate the factors determining the interaction of hydrogen with the surface of Pt/SO_4^<2->-ZrO_2, the rate of hydrogen adsorption and generation of acidic sites were measured for different types of Pt/SO_4^<2->-ZrO_2 whose surface acidities were controlled. It was revealed that the rate and hydrogen uptake increases with an increase in the surface acidity.
It was also proven fro the first time that the formation of protonic acid sites occurs on the surfaces of Pt/WO_3-ZrO_2 and WO_3-ZrO_2 on heating in the presence of hydrogen. The formation of the protons was much easy for Pt/WO_3-ZrO_2 than for WO_3-ZrO_2. The mechanism for the formation of the protons on WO_3-ZrO_2 was elucidated in relation with the surface structure. The kinetic analysis of the hydrogen adsorption revealed that the slow steps were spillover step for Pt/WO3-ZrO2 and and the surface diffusion step for WO_3-ZrO_2.
The catalytic activities of Pt/SO_4^<2->-ZrO_2 and Pt/WO_3-ZrO_2 for heptane isomerization were measured to determine the factors governing the selectivity. Pt/WO_3-ZrO_2 exhibited higher selectivity than Pt/SO_4^<2->-ZrO_2 while the conversion rate was higher for Pt/SO_4^<2->-ZrO_2. It was concluded that the selectivity is governed by the acid strength and the rate of surface diffusion of hydrogen. The participation of the spiltover hydrogen in the isomerization mechanisms is clarified.
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