Selective Amplification of CO Bond Hydrogenation on Pt/TiO₂: Catalytic Reaction and Sum‐Frequency Generation Vibrational Spectroscopy Studies of Crotonaldehyde Hydrogenation

Abstract

The hydrogenation of crotonaldehyde in the presence of supported platinum nanoparticles was used to determine how the interaction between the metal particles and their support can control catalytic performance. Using gas-phase catalytic reaction studies and in situ sum-frequency generation vibrational spectroscopy (SFG) to study Pt/TiO2 and Pt/SiO2 catalysts, a unique reaction pathway was identified for Pt/TiO2, which selectively produces alcohol products. The catalytic and spectroscopic data obtained for the Pt/SiO2 catalyst shows that SiO2 has no active role in this reaction. SFG spectra obtained for the Pt/TiO2 catalyst indicate the presence of a crotyl-oxy surface intermediate. By adsorption through the aldehyde oxygen atom to an O-vacancy site on the TiO2 surface, the C=O bond of crotonaldehyde is activated, by charge transfer, for hydrogenation. This intermediate reacts with spillover H provided by the Pt to produce crotyl alcohol.

Nanocatalysis I: Synthesis of Metal and Bimetallic Nanoparticles and Porous Oxides and Their Catalytic Reaction Studies

“…10d). A similar trend was confirmed in crotonaldehyde hydrogenation, in which the activity of a Pt/TiO 2 catalyst was increased fourfold and over 50 % alcohol products were obtained selectively, compared to those of Pt/SiO 2 [74]. Recently, nhexane reforming was carried out over various kinds of porous oxides including Al 2 O 3 , TiO 2 , Nb 2 O 5 , Ta 2 O 5 , and ZrO 2 to investigate support-dependent catalytic selectivity toward branched C 6 isomers which are desired products for high-octane gasoline in the oil refining process [49].…”

Polymer-Encapsulated Metallic Nanoparticles as a Bridge Between Homogeneous and Heterogeneous Catalysis

“…Looking ahead into the field of heterogeneous catalysis we can point out two directions that can be evolved on the basis of the above-mentioned conclusions. One approach is the development of highly stable catalytic mesostructures in which the polymeric matrix that encapsulates the metal surface is substituted with a metaloxide support that can act as a co-catalyst [59][60][61]. The metal-oxide support can (i) tune the electronic properties of the metal and (ii) act as a co-catalyst and directly activate the reactants during the catalytic process.…”

Role of Hot Electrons and Metal–Oxide Interfaces in Surface Chemistry and Catalytic Reactions

“…Current work is underway that appears to show that a similar mechanism applies to a range of aldehyde hydrogenation reactions on Pt/TiO 2 catalysts as well as to Pt supported on other SMSI-active oxides. 163,164 The theory that charge transfer between a metal catalyst and a semiconductor support alters the electron structure of the metal catalyst has been investigated by XPS. 153−157 Fung performed one of the first XPS studies looking at charge transfer in a Pt/ TiO 2 catalyst.…”