Sustainable Production of 1-Propanol via the Selective Hydrogenolysis of Glycerol Over a Tailored Iridium–Rhenium Oxide Catalyst Supported on HUSY Zeolite

Abstract

1-Propanol (1-PO) is a widely used industrial solvent and an important chemical intermediate. In this study, the hydrogenolysis of glycerol to 1-PO was investigated over conventional proton-form ultrastable (HUSY) zeolite, monometallic Ir-loaded HUSY (Ir-HUSY), and Ir–ReO_x metal–metal oxide supported on HUSY (IrRe-HUSY). The IrRe-HUSY catalysts, which were prepared via a sequential two-step incipient wetness impregnation method, exhibited favorable physicochemical properties, including improved acid properties and uniform metal dispersion. Therefore, the bimetallic IrRe-HUSY catalysts demonstrated a considerably higher catalytic performance, achieving a glycerol conversion of 78.9% and 1-PO yield of 39.2%, than HUSY zeolite and Ir-HUSY, which demonstrated only 32.9% glycerol conversion and 11.1% 1-PO yield. This improvement in the catalytic properties of the IrRe-HUSY catalysts was attributed to the synergistic effects among the three catalyst components: (1) ReO_x clusters facilitated glycerol adsorption and activation; (2) Ir nanoparticles promoted C─O bond cleavage and hydrogenation; and (3) the acidic HUSY support enhanced dehydration steps. Additionally, the effects of operating conditions, such as catalyst loading, reaction time, and temperature, on 1-PO production were systematically investigated. The surface structure of IrRe-HUSY and the mechanistic pathway for glycerol hydrogenolysis over the IrRe-HUSY catalyst were elucidated.