Selective Hydrogenolysis of Glycerol to 1,3-Propanediol over Rhenium-Oxide-Modified Iridium Nanoparticles Coating Rutile Titania Support

Abstract

The effect of support in Ir-ReO x catalysts for glycerol hydrogenolysis to 1,3-propanediol was investigated. Rutile TiO2 support showed high activity, even higher than previously reported SiO2 support. Anatase TiO2, C, ZrO2, CeO2, Al2O3, and MgO supports showed very low activity of supported Ir-ReO x pairs. Higher Ir-based 1,3-propanediol productivity of Ir-ReO x /rutile catalyst was obtained at the initial stage even with lower Re/Ir ratio (typical Ir loading amount, 4 wt %, nominal ratio of 0.25; actual ratio of 0.24) without addition of H2SO4 than that of Ir-ReO x /SiO2. The 1,3-propanediol productivity over Ir-ReO x catalysts showed dependency on catalyst compositions (metal loading amount), and the relationship between catalyst structure and activity was further established over Ir-ReO x /rutile. Relatively high Ir loading amount in comparison with small surface area (6 wt %, on 6 m2 g–1 rutile TiO2) showed the highest activity (Ir-based activity). From combined characterization results altogether (TPR, TEM, XPS, XAS, CO adsorption, CO FT-IR) with a kinetics study, the Ir metal particles interacted with the partially oxidized ReO x cluster (average valence of Re: +3) almost totally covering the surface of rutile TiO2 particles, and the active site was the Ir-ReO x interface. Small amounts of Ir species (∼20%) were incompletely reduced; however, such IrO x species as well as rutile TiO2 support were not directly involved in glycerol hydrogenolysis. The role of rutile support was regarded as providing a unique environment for stabilization of uniform and small Ir-ReO x particles with very high surface density on rutile TiO2, which increased the number of active sites per Re amount.

Selective Hydrogenolysis of Erythritol over Ir−ReOx/Rutile‐TiO2 Catalyst

“…The two standard catalysts in our previous studies (Table 1, entries 1 and 2), Ir−ReO x /TiO 2 (4 wt % Ir, Re/Ir=0.25) showed about twofold higher activity (total weight‐based or Ir‐based) than Ir−ReO x /SiO 2 (4 wt % Ir, Re/Ir=1), as indicated by that about half reaction time over Ir−ReO x /TiO 2 was required to obtain the same conversion level as over Ir−ReO x /SiO 2 . Such about twofold difference of activity between these catalysts has been also reported for glycerol hydrogenolysis [32] . Considering that Ir−ReO x /TiO 2 has one quarter the Re content of Ir−ReO x /SiO 2 , the activity difference was even larger when calculated based on Re.…”

“…In the present work, we investigated the performance of Ir−ReO x /TiO 2 (4 wt % Ir, Re/Ir=0.25) catalyst in the erythritol hydrogenolysis, and typical catalyst of Ir−ReO x /SiO 2 (4 wt % Ir, Re/Ir=1) was also used for comparison. The Ir particle size in these catalysts are similar (2 nm), while the surface density of Ir particles on support is much different because of the difference of support surface area [24,32] . Higher 1,4‐BuD selectivity was obtained over Ir−ReO x /TiO 2 catalyst than over Ir−ReO x /SiO 2 at relatively low conversion level.…”

Hydro(deoxygenation) Reaction Network of Lignocellulosic Oxygenates

“…Rh−Ir−ReO x /SiO 2 has the potential for higher activity in the hydrogenation of FUR to tetrahydrofurfuryl alcohol intermediate in the low‐temperature step than that with Ir−ReO x /SiO 2 , although the hydrogenation activity was lower than that of Pd−Ir−ReO x /SiO 2 . In recent years, the capability of Ir−ReO x /SiO 2 as a versatile catalyst was explored for derivatizing lubricant base oil of C 22 –C 34 with unprecedented control, the preparation of 1,3‐propanediol through selective C−O bond rupture of glycerol, and HDO of vegetable oil with C 14 –C 18 . As part of upgrading, a MoO x ‐modified Ir/SiO 2 catalyst, with a Mo/Ir ratio of 0.13 (Ir−MoO x /SiO 2 ), exhibits the highest product yield (78–96 %) under mild reaction conditions for the production of jet and diesel fuels and lubricant oils .…”

Direct Transformation of Glycerol to Propanal using Zirconium Phosphate‐Supported Bimetallic Catalysts

“…[7,[9][10][11][12] Among them, one of the most promising approaches is the catalytic hydrogenolysis of glycerol into propanediols, such as 1,3-propanediol (1,3-PDO) and 1,2-propanediol (1,2-PDO). [13,14] It is worth noting that highly efficient and selective hydrogenolysis of glycerol to 1,2-PDO has been achieved on various catalytic systems. [7,[15][16][17][18][19][20] Although the dehydration of 1,2-PDO to propanal (PA) has also been studied using various types of heterogeneous catalysts, the catalytic activity and selectivity to PA still remains a huge challenge.…”