Details

Autor(en) / Beteiligte

• Hsu, Chin-Yao
• Chiu, Tsai-Chin
• Shih, Meng-Hung
• Tsai, Wei-Je
• Chen, Wei-Yi
• Lin, Chiu-Hsun

Titel

Effect of Electron Density of Pt Catalysts Supported on Alkali Titanate Nanotubes in Cinnamaldehyde Hydrogenation

Ist Teil von

• Journal of physical chemistry. C, 2010-03, Vol.114 (10), p.4502-4510

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2010

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Pt nanoparticles of diameter 0.5−1.5 nm were dispersed homogeneously on the inner and outer surfaces of alkali metal titanate nanotubes (M2Ti3O7, M = Li+, Na+, and K+) by ion exchange with Pt(NH3)2Cl2 followed by calcination in ambient air at 673 K and reduction in H2 at 448 K. Both XPS and DRIFTS revealed that these titanate nanotubes donated their electrons to the Pt particles, yielding a negative Pt oxidation state, and that the degree of electron donation increased with the size of the alkali metal cation. The high electron density of the Pt particles promoted the activation of both CC and CO functional groups in cinnamaldehyde. Therefore, the order of the catalytic activity in the hydrogenation of cinnamaldehyde was Pt/KTNTs > Pt/NaTNTs > Pt/LiTNTs. Since the Pt particles were very small, Pt/MTNTs selectively hydrogenated the CC bond, yielding a hydrocinnamaldehyde with selectivities of 80−87% (at cinnamaldehyde conversions of 27−50%). The alkali metal ions of the titanate nanotubes were able to modify the mode of adsorption of cinnamaldehyde. Therefore, when a KOH promoter was added to the reaction mixture, cinnamyl alcohol became the main product and the cinnamyl alcohol selectivities were 77−83% (at cinnamaldehyde conversions of 49−74%).