Preparation of bimetallic gold catalysts by redox reaction on oxide-supported metals for green chemistry applications

• Oxide-supported Au bimetallic catalysts were prepared by a redox-method.
• Redox-method extended variation in the bimetallic composition and reactions over them.
• The low-loaded Au bimetallic catalysts showed high activity in the oxidation reactions.
• The Au/Pt, Au/Pd, Au/Ru catalysts were efficient in glycerol transformation reactions.

The major problem in successful preparation of bimetallic supported catalysts is the formation of an extended contact area between the monometallic phases. The selective deposition of Au on the surface of nanoparticles of a primary oxide-supported metal has been performed by a redox method that is based on the reduction of the second metal (M2) ions with hydrogen adsorbed on the surface of first metal (M1) or with M1 itself. The gold containing bimetallic catalysts with different atomic ratios and metal combinations Au–M1 (M1 = Pd, Pt, Rh, Ru, and Au–RuOx) deposited on oxide supports (TiO2, SiO2 or θ-Al2O3) have been prepared by this method with special emphasis on the preparation of low-loaded gold containing bimetallic catalysts. The samples were characterized by X-ray diffraction analysis (XRD), scanning transmission electron microscopy (STEM), temperature programmed reduction (TPR) analysis, CO adsorption, X-ray photoelectron spectroscopy (XPS), Diffuse reflectance Fourier-transform IR spectroscopy of adsorbed CO (DRIFTS-CO). By varying the conditions of the preparation procedure, the direct contact area was obtained either between two metal phases (Au/M1) or between metal and a metal oxide phase (Au/M1Ox) that changed the catalytic properties of primary supported M1. The prepared bimetallic catalysts exhibited the high activity in various reactions: from the Cl-VOC oxidative degradation to the up-to-date “green” reactions aimed at the synthesis of fine chemicals from ethanol and glycerol.

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