- 作者: 何瑞文
- 作者服務機構: 成功大學化學系
- 中文摘要: The dehydroxylation and rehydroxylation properties of titania (Degussa P-25) were investigated. FTIR and TPD-MS data indicate that hydroxyl groups are not completely removed at 500.degree.C in vacuo, and rehydration/rehydroxylation occur under helium (water content <1ppm) flow at room temperature. In addition, repeating dehydroxylation/rehydroxylation treatments for ten times does not significantly modify the dehydroxylation/rehydroxylation property of titania surface. Desorption of hydrogen from titania was observed at 535.degree.C after titania was reduced above 400.degree.C. The maximum surface density of hydrogen was determined to be 0.75H atom/nm/sup 2/. TPD data show four types of hydrogen on 3% titania supported cobalt catalysts: hydrogen adsorbed on cobalt metal (desorption temperature around 100.degree.C), reverse spillover hydrogen (150- 250.degree.C), hydrogen from H-TiO/sub 2-x/-Co interacting species (.sim.330.degree.C), and recombined hydrogen from Ti/sup 3+/-H on titania (.sim.535.degree.C). The absence of hydrogen desorption peak at 535.degree.C for titania supported cobalt reduced above 400.degree.C can be explained in terms of the migration of H-TiO/sub 2-x/ moieties onto cobalt metal surface during reduction. Removal of hydroxyl groups by thermal treatment before reduction enhanced the amount of hydrogen desorption from normal cobalt surface. This indicates that the hydroxyl groups play a role in the surface migration of H-TiO/sub 2-x/.
- 英文摘要: --
- 中文關鍵字: Surface; Hydroxyl; Titania; Cobalt Catalyst; Titanium; Dehydroxylation
- 英文關鍵字: 表面;羥基;鈦白;鈷催化劑;鈦;脫羥基