Tuning the selectivity of catalytic hydrogenation of fumaric acid with supercritical CO2

Abstract

The catalytic hydrogenation of fumaric acid, a prominent bioplatform molecule, was evaluated over PdRe/SiO₂ within a variety of reaction media compositions comprising methanol, water, supercritical CO₂, and their assorted combinations with H₂, across a range of temperature and pressure regimes. Meticulous manipulation of the reaction media composition facilitated the precise modulation of catalytic activity to favor specific hydrogenation products. For instance, within a water-saturated supercritical CO₂ medium, γ-butyrolactone exhibited a noteworthy 89 % selectivity at 188°C under 250 bar total pressure, whereas in the methanol-containing supercritical CO₂ system, hydrogenation displayed a remarkable 91 % selectivity towards tetrahydrofuran at 175°C and 250 bar. This investigation underscores the multifaceted influence of CO₂, extending beyond its pressure-derived effects - it functions as a solvent, selectively favoring catalytic pathways and enhancing product selectivity.