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| 題 名 | Reducibility of Supported Vanadium Oxide Catalysts=被擔持釩氧化物觸媒之還原性 |
|---|---|
| 作 者 | 鄭紀民; 郭育佐; 簡錦昌; | 書刊名 | 興大工程學報 |
| 卷 期 | 8:1 1997.01[民86.01] |
| 頁 次 | 頁9-18 |
| 分類號 | 345.421 |
| 關鍵詞 | 表面釩氧化物; 混合擔體; 添加物; 還原能力; Surface vanadium oxide; Mixed oxide support; Promoter; Reducibility; |
| 語 文 | 英文(English) |
| 中文摘要 | A series of SnO��/SiO�畝nd CeO��/SiO�痂ixed oxide supported V�烙�θat alysts were investigated by temperature programmed reduction (TPR). The TPR studies indicated that the reducibility of the surface vanadium oxide was affected by the support and promoter. At low concentration of SnO �� and CeO �� (3%) on silica, the silica surface is not totally covered by SnO �� and CeO ��. An interaction between the surface vanadium oxide and the unoccupied silica sites was preferentially formed and exhibited a maximum reduction temperature (Tmax) at ∼ 650 °C. The temperature was similar to the maximum reduction temperature of the V �� O �� /SiO �� system (∼ 660 ° C ).At high concentrations of SnO �� (30%) on silica, the reduction temperatures of the surface vanadium oxide species (∼ 351, ∼ 528, ∼ 713, ∼ 758, and ∼ 852 ° C) were significantly different from those of V �� O �� /SiO ��. This indicated that a monolayer coverage of tin oxide on silica is reached, and surface vanadium oxide reacted with surface tin oxide to form a surface VO �X -SnO �X. The maximum reduction temperatures of the surface vanadium oxide on 30% CeO �� /SiO �� (∼ 501, ∼ 651, and ∼ 852 ° C ) were not significantly different from those of the surface vanadium oxide on 30% CeO �� /SiO ��.The presence of the Tmax point at ∼ 651 ° C indicated that the surface silica sites were available for the surface vanadium oxide species to form a surface VO �X -SiO �� at high concentration of CeO �� (30%). The reducibility of surface vanadium oxide was also affected by various promoters (such as Cr, Nb, and W). In general, supported V �� O �� catalyst promoting by Nb or W was not as easily reducible as that prommoted by Cr. The addition of Cr into the 3% V �� O �� 30% SnO �� /SiO �� and 3% V �� O �� 30% CeO �� /SiO �� catalysts significantly affected the reducibility of these catalysts. The lower Tmax points at ∼ 356 and ∼ 613 ° C for the Cr-promoted 3% V �� O �� 30% SnO �� /SiO �� catalyst and at ∼ 499 ° C for the Cr-promoted 3% V �� O �� 30% CeO �� /SiO �� catalyst were observed. |
| 英文摘要 | 由控溫還原實驗結果可知,表面釩氧化物在 SnO��/SiO�砟� CeO��/SiO�租V合擔 體之還原性質與擔體及添加物皆有密切之關係。在低 SnO �砟� CeO �紊@度( 3% )之 SnO �� /SiO �砟� CeO �� /SiO �租V合擔體, 由於 SnO �砟� CeO �砲憫馴�覆蓋 SiO �砟妒磾� , 故表面釩氧化物之還原溫度(約 650 ° C )與表面釩氧化物在 SiO �紋慞擗岐棜鼒贖� ( 660 ° C )非常接近。在高 SnO �砟� CeO �紊@度( 30% )之 SnO �� /SiO �砟� CeO �� /Si �租V合擔體, 表面釩氧化物在 30% SnO �� /SiO �砟岐棜鼒贖蛂] 351 ° C、 528 ° C、713 ° C、758 ° C、852 ° C )與其在 SiO �砟岐棜鼒贖蛂] 660 ° C )差異很 大, 可證明 SnO �祐馴�覆蓋 SiO �砟妒磾情A 而且表面釩氧化物與表面錫氧化物形成 VO �X -SnO �X之鍵結。相較之下,表面釩氧化物在 30%CeO �� /SiO �紋慞擗岐棜鼒贖蛂] 501 ° C、 651 ° C、852 ° C )與其在 3%CeO �� /SiO �紋慞擗岐棜鼒贖袢L明顯之變化及還原 溫度( 651 ° C )之存在,可證明 CeO �祠疇憫馴�覆蓋 SiO �砟妒磾情A而有 VO �X SiO �砟岐鉾異峖芋C 添加物( Cr, Nb, W )對表面釩氧化物之還原性質,具有不同程度之影響 ,一般而言,添加 W 與 Nb 後觸媒之還原性低於添加 Cr 者,故 Cr 對 3% V �� O �� 30% SnO �� /SiO �砟� 3% V �� O �� 30% CeO �� /SiO �砟岐棜麈鄐O影響較大。 添加 Cr 於 3% V �� O �� 30% SnO �� /SiO �紕眼C中使還原溫度低至 356 ° C 及 613 ° C,而添加 Cr 於 3% V �� O �� 30% CeO �� /SiO �祠狫棜鼒贖蚼飢C至 499 ° C。 |
本系統中英文摘要資訊取自各篇刊載內容。