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The hydrogenolysis of erythritol using an Ir-ReO(x)/SiO(2) catalyst was performed for the production of butanediols, which are widely used as a raw material of polymers. The activity and selectivity to butanediols on Ir-ReO(x)/SiO(2) was much higher than that on conventional hydrogenolysis catalysts. The maximum selectivity to 1,4- and 1,3-butanediols reached 33 and 12 % at 74 % conversion, respectively. The erythritol conversion and selectivity to butanediols was almost maintained during four repeating tests if small amounts of acid were added to the reaction and the catalyst was calcined again. The reaction kinetics, reactivity trends, and characterization results indicate a direct hydrogenolysis mechanism in which the hydride species on the Ir metal surface attacks the alkoxide species on the 3D ReO(x) clusters. Based on the production of erythritol by the fermentation of glucose and glycerol, erythritol hydrogenolysis may be a promising pathway for the production of biobutanediols.

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The structural change of Ir/SiO 2 and Ir−ReO x /SiO 2 during the temperature programmed reduction with H 2 was investigated using in situ Ir L 3 -edge and Re L 3 -edge quick-scanning X-ray absorption fine structure in the combination of temperature programmed reduction with H 2 , XRD, the measurement of CO adsorption, Raman spectroscopy, and X-ray photoelectron spectroscopy. The metal oxide on Ir−ReO x /SiO 2 was much more easily reduced than that on monometallic Ir/SiO 2 and ReO x /SiO 2 , which is explained by the interaction between trioxo Re species and the IrO 2 phase. The metal structure of Ir−ReO x /SiO 2 constructed after reduction at 485−595 K is the cuboctahedron Ir metal particles covered with three-dimensional ReO x clusters.