1996 Fiscal Year Final Research Report Summary
Novel functions of composite catalysts derived from Pd and support metal oxides-mechanism and utilization
| Project/Area Number |
07650932
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 |
TAKEZAWA Nobutsune Hokkaido University, Faculty of Engineering, Professor, 工学部, 教授 (60001715)
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| Co-Investigator(Kenkyū-buntansha) |
IWASA Nobuhiro Instructor, Faculty of Engineering, Hokkaido University, 工学部, 助手 (30223374)
FUJITA Shinichiro Instructor, Faculty of Engineering, Hokkaido University, 工学部, 助手 (80156869)
SHIMOKAWABE Masahide Associate Professor, Faculty of Engineering, Hokkaido University, 工学部, 助教授 (40125323)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Pd / ZnO / Steam reforming of methanol / Dehydrogenation of methaniol / Methyl formate / Pd-Zn alloy / PtZn alloy / Novel alloy catalysts |
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| Research Abstract |
Pd/ZnO exhibited anomalously high catalytic performance for the steam reforming of methanol and the dehydrogenation to HCOOCH_3 among various supported Pd ctalysts. The selectivities for the steam reforming and the dehydrogenation to HCOOCH_3 were achieved at 99.5% and 80%, respectively. In contraast, the other supported Pd catalysts showed the selectivities of 0-40% and 0%, respectively for the steam reforming and the dehydrogenation to HCOOCH_3. The catalytic performance of Pd/ZnO for the steam reforming and the dehydrogenation was greatly improved by previously reducing the catalyst at higher temperatures. The increased catalytic performace was attributed to PdZn alloys formed in the previous reduction of the catalyst. By XP spectroscopy, it was revealed that electron transfer took place from Pd to Zn in the formation of PdZn alloys. Over the alloyed catalysts, formaldehyde species formed in the reactions were effectively attacked by -OH or CH_3O-, being transformed into CO_2 and H_
… More
2 or HCOOCH_3. Over the other catalysts containing unalloyed Pd, the formaldehyde species decomposed selectively to CO and H_2 in the steam steam reforming and the dehydrogenation of methanol. It was suggested that formaldehyde species were stabilized on positively charged Pd sites in eta^1 (O) -form in the reactions over PdZn alloys, and subjected to the nucleophilic addition of -OH or CH_3O-. On the basis of the proposed mechanism of the generation of new catalytic function of Pd, novel Pd_<3.1>Zn_<6.9> and PtZn alloy catalysts were developed. These alloys showed high selectivity for the dehydrogenation of methanol to HCOOCH_3 as well as the steam reeforming. Experimemts were carried out over Pd/ZnO catalysts prepared by various preparation methods. Pd/ZnO (10wt% Pd) obtained by precipitation of Pd (II) and Zn (II) with a Na_2CO_3 solution exhibited best performance for the steam reforming among the Pd catalysts so far studied. The activity of Pd/ZnO was twice that for Cu/SiO_2 (30wt% Cu) previously studied. Less
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