The Guerbet condensation reaction is an alcohol coupling reaction that has been known for more than a century. Because of the increasing availability of bio-based alcohol feedstock, this reaction is of growing importance and interest in terms of value chains of renewable chemical and biofuel production. Due to the specific branching pattern of the alcohol products, the Guerbet reaction has many interesting applications. In comparison to their linear isomers, branched-chain Guerbet alcohols have extremely low melting points and excellent fluidity. This review provides thermodynamic insights and unravels the various mechanistic steps involved. A comprehensive overview of the homogeneous, heterogeneous and combined homogeneous and heterogeneous catalytic systems described in published reports and patents is also given. Technological considerations, challenges and perspectives for the Guerbet chemistry are discussed.

A series of Ce1−x Eu x O2−x/2 mixed oxides was synthesized by coprecipitation. The solids were characterized by means of XRF, SBET, XRD, UV−vis, and Raman techniques, and their catalytic activities toward CO oxidation were tested. A solid solution, with CeO2 F-type structure, is formed for europium contents (measured as Eu2O3 by XRF) ≤20% wt. For higher contents, the solid solution is not formed, but a physical mixture is detected. The existence of oxygen vacancies in the solids with Eu2O3 contents between 3 and 17% wt was demonstrated by the presence of bands at 532 and 1275 cm−1 in their Raman spectra. The catalytic performances of the solids correlate with the amount of these punctual defects in the solid solution.

Potassium hexacyanoferrate K 3 [Fe(CN) 6 ] (Acros Organics, 98%), potassium hexacyanocobaltate K 3 [Co(CN) 6 ] (Acros Organics, 98%), cobalt chloride hexahydrate CoCl 2 .6H 2 O (Fluka, ≥ 98%), niquel chloride hexahydrate NiCl 2 .6H 2 O (Fluka, ≥ 98%), manganese chloride tetrahydrate MnCl 2 .4H 2 O (Sigma-Aldrich, 98%+), cupper chloride dihydrate CuCl 2 .2H 2 O (Sigma-Aldrich, 98%+). All the solutions were prepared with Millipore Milli-Q water.Synthesis procedure: In a typical synthesis, 100 mL of an aqueous solution of 0.01M K 3 [M(CN) 6 ] (M = Fe or Co) was added drop by drop to 100 mL of an aqueous solution of 0.02 M of the respective metal chloride, at room temperature (25 ºC aprox.)and stirring constant. After total addition of hexacyanometallate solution, the obtained slurry was kept under stirring during one hour and then was washed with Milli-Q water three times, by centrifugation. The execss of water was removed from the obtained solid at 40 ºC, under vacuum. Finally, the collected powder was leaved at 40 ºC during 2 hours, in an oven.Methods: Metal content in the PB catalysts was analyzed with a JEOL-JMS6400 environmental scanning electron microscope equipped with an Oxford Instruments X-ray elemental analyzer. Thermogravimetric analysis (TGA) was performed with powder samples using a TGA/SDTA851 Mettler Toledo with a MT1

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