Effect of electron density of Pt catalysts supported on alkali titanate nanotubes in cinnamaldehyde hydrogenation

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

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50 Citations (Scopus)

Abstract

Pt nanoparticles of diameter 0.5-1.5 nm were dispersed homogeneously on the inner and outer surfaces of alkali metal titanate nanotubes (M 2Ti3O7, M ) Li+, Na+, and K+) by ion exchange with Pt(NH3)2Cl 2 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 CdC and CdO 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 CdC 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%).

Original languageEnglish
Pages (from-to)4502-4510
Number of pages9
JournalJournal of Physical Chemistry C
Volume114
Issue number10
DOIs
Publication statusPublished - 2010 Mar 18

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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