Abstract
We have prepared, by a sol-immobilization method, bimetallic catalysts with different Au:Pt atomic ratios supported on commercial SrCO3. The catalytic performance for the oxidation reaction of benzyl alcohol of such materials was compared to the monometallic counterparts, aiming at the obtaining of the best composition of the material. It was found that the Au:Pt atomic ratio presents a remarkable effect on the system performance, i.e., Pt-rich systems are more selective; however, less active. Thus, an equilibrium related to the activity and selectivity of the system was obtained by considering the yield of the system. Also, some density functional theory (DFT) insights were obtained by using a cluster of 14 atoms of Au and 1 or 2 atoms of Pt. X-ray photoelectron spectroscopy, elemental mapping in scanning transmission electron microscopy before and after catalyst usage, flame atomic absorption spectroscopy, Rietveld refinement, among other techniques, were used and associated to the experimental data, which allowed us to propose a catalytic mechanism for the system, which was important since SrCO3 has not been considered before as catalyst support for alcohol oxidation reactions.
Highlights
Optimizing bimetallic systems by exploring their electronic and structural effects is essential for the design of new and more efficient catalysts.[1,2,3] Pt and Pd nanoparticles (NPs) were the first catalysts to present activity in oxidation reactions,[4,5] their deactivation is a great issue, which is difficult to solve due to their easy overoxidation and poisoning from byproducts.[6]
Some of us have demonstrated that strontium-based catalytic supports present remarkable effects on the oxidation of benzyl alcohol under O2 pressure, an important feature not explored in the literature
SrCO3 is cheaper than many other materials largely used as support for catalytic applications, e.g., Al2O3, TiO2, and CeO2, and presents unique electronic properties,[35] which can be beneficial to the activity and/or selectivity of catalysts
Summary
Optimizing bimetallic systems by exploring their electronic and structural effects is essential for the design of new and more efficient catalysts.[1,2,3] Pt and Pd nanoparticles (NPs) were the first catalysts to present activity in oxidation reactions,[4,5] their deactivation is a great issue, which is difficult to solve due to their easy overoxidation and poisoning from byproducts.[6] When Au NPs were found to be very active and selective for oxidation reactions by Prati and co-workers,[7,8,9] and more robust with respect to deactivation processes, their utilization dramatically increased. Mixing Au NPs with Pt or Pd NPs have demonstrated the possibility of merging. The exceptional performance of bimetallic catalysts when compared to monometallic ones is not fully understood due to the possibility of different combinations among reactants, composition, and reaction conditions,[14] which usually provides only isolated applications. Several examples are demonstrated in the literature. They have reported that nonsupported AuPt NPs exhibited improved electrochemical
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