Photocatalytic decomposition of 4-nitrophenol on Ti-containing MCM-41

• Published in: Catalysis today 2005-04, Vol.101 (3), p.299-305
• Main Authors: Do, Yoon-Jeong, Kim, Jin-Ho, Park, Jin-Hwan, Park, Seong-Soo, Hong, Seong-Soo, Suh, Cha-Soo, Lee, Gun-Dae
• Format: Article
• Language: English
• Subjects: 4-Nitrophenol; Catalysis; Chemistry; Exact sciences and technology; General and physical chemistry; Photocatalytic decomposition; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Ti-containing MCM-41; UV and visible light
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2005.03.009

A series of Ti-containing MCM-41 samples, such as Ti-MCM-41 with variable Si/Ti ratios and Cr–Ti-substituted TiO 2-loaded MCM-41 having different TiO 2 loading, were prepared and studied for the photocatalytic decomposition of 4-nitrophenol in UV and visible light. The samples were characterized using surface area measurement, XRD, FT-IR, and UV–vis DRS techniques. In the case of the Ti-MCM-41 samples with Si/Ti ratios higher than 20 which were found to have typical mesoporous structure, the framework incorporation of Ti into MCM-41 increased with decreasing Si/Ti ratio. On the contrary, the Ti-MCM-41 with lower Si/Ti ratio (Si/Ti = 10) shows low structural integrity and the formation of Ti-oxide species, leading to a considerable decrease in surface area. In the case of Cr–Ti-substituted TiO 2-loaded MCM-41 samples, significant absorption occurs in visible light and the absorption in both UV and visible region increases with increasing TiO 2 loading. However, when the amount of TiO 2 loaded on Cr–Ti-MCM-41 increased above 33 wt.%, the absorption in visible light increased slightly. Thus, it seems that, at higher TiO 2 loading, some TiO 2 particles are not closely bound to the wall of Cr–Ti-MCM-41. The photocatalytic activities of Ti-containing MCM-41 samples were strongly influenced by the amount of Ti. Under UV illumination, the highest photocatalytic activity for photocatalytic decomposition of 4-NP was observed for the Ti-MCM-41 having Si/Ti ratio of 20. Among various Ti-containing MCM-41 materials prepared in this work, only Cr–Ti-substituted TiO 2-loaded MCM-41 catalysts exhibited discernable photocatalytic activities in visible light, and their photocatalytic activities increased considerably with increasing TiO 2 loading up to 33 wt.%. Further increase in TiO 2 loading enhanced photocatalytic activity slightly.