| Co-Investigator(Kenkyū-buntansha) |
IWASA Nobuhiro Hokkaido Univ., Grad. School of Eng., Inst., 大学院・工学研究科, 助手 (30223374)
FUJITA Shinichiro Hokkaido Univ., Grad. School of Eng., Inst., 大学院・工学研究科, 助手 (80156869)
SHIMOKAWABE Masahide Hokkaido Univ., Grad. School of Eng., Asso. Prof., 大学院・工学研究科, 助教授 (40125323)
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| Research Abstract |
Pd supported on ZnO, GaィイD22ィエD2OィイD23ィエD2, InィイD22ィエD2OィイD23ィエD2, or CdO, Pt supported on ZnO, GaィイD22ィエD2OィイD23ィエD2, or InィイD22ィエD2OィイD23ィエD2, or Ru supported on InィイD22ィエD2OィイD23ィエD2 exhibited anomalously high selectivity for (a) dehydrogenation of CHィイD23ィエD2OH to HCOOCHィイD23ィエD2 and (b) of CHィイD23ィエD2CHィイD22ィエD2OH to CHィイD23ィエD2COOCィイD22ィエD2HィイD25ィエD2, c the steam reforming of methanol, and (d) hydrogenolysis of ester (HCOOCHィイD23ィエD2 or CHィイD23ィエD2COOCィイD22ィエD2HィイD25ィエD2) to alcohol (CHィイD23ィエD2OH and CHィイD23ィエD2CHィイD22ィエD2OH ) among various supported VIII group metal catalysts. The selectivity for the reaction (a), (b), c or (d) was greatly improved upon the formation of bimetallic alloys (Pd-Zn, Pd-Ga, Pd-Ga, Pt-Zn, Pt-Ga, and Pt-In ). Over the alloyed catalysts aldehyde species (HCHO or CHィイD23ィエD2CHO) formed in the reactions were stabilized, and (1) effectively attacked by CHィイD23ィエD2O- (or, CHィイD23ィエD2CHィイD22ィエD2O-) , -OH and hydrogen, being transformed into HCOOCHィイD23ィエD2
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(or CHィイD23ィエD2COOCィイD22ィエD2HィイD25ィエD2) and COィイD22ィエD2/HィイD22ィエD2 respectively in the dehydrogenation of CHィイD23ィエD2OH (or CHィイD23ィエD2CHィイD22ィエD2OH ) and the steam reforming of CHィイD23ィエD2OH or (2) attacked by hydrogen, being selectively converted into CHィイD23ィエD2OH ( or CHィイD23ィエD2CHィイD22ィエD2OH ) in the hydrogenolysis of HCOOCHィイD23ィエD2 (or CHィイD23ィエD2COOCィイD22ィエD2HィイD25ィエD2). Over the other catalysts containing unalloyed Pd or Pt, HCHO or CHィイD23ィエD2CHO species were readily decarbonylated to COィイD22ィエD2/HィイD22ィエD2 or CO/CHィイD24ィエD2 in dehydrogenation of CHィイD23ィエD2 or CHィイD23ィエD2CHィイD22ィエD2OH, steam reforming of CHィイD23ィエD2OH and hydrogenolysis of HCOOCHィイD23ィエD2 or CHィイD23ィエD2COOCィイD22ィエD2HィイD25ィエD2.
Mechanism of the Pd-Zn alloy formation was also studied in the reduction of Pd/ZnO catalysts. It was found that hydrogen initially retained in Pd spilled rapidly over to ZnO. The ZnO was then reduced to metallic Zn, being transformed into PdZn. Once the alloy produced, the spillover hydrogen atoms on the alloys to ZnO was greatly suppressed, resulting in the selective formation of PdZn in the course of the reduction of Pd/ZnO. Less
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