We demonstrate that refinery-grade propane/propylene mixtures, rather than polymer-grade propylene, can be used for industrial propylene hydroformylation with Rh/BiPhePhos catalyst complexes. Because propylene hydroformylation is selective, an enriched propane stream is produced, which may be recycled for producing more propylene. In addition to the potential energy savings and associated economic/environmental benefits, the mixed propane/propylene feed also provides reaction benefits by volumetrically expanding the reaction mixture to yield gas-expanded liquids (GXLs) with tunable physicochemical properties. Unlike conventional reaction media, the H-2/CO ratio in GXL media can be enhanced by simply increasing the partial pressure of propane. For rhodium/triphenylphosphine catalyzed propylene hydroformylation in propane-expanded liquids, performed between 343.15 K and 363.15 K and pressures up to 2.0 MPa, the n/i aldehyde ratio is increased by up to 45% (corresponding to an increase in n-aldehyde selectivity from 71% to 78%). This is attributed to the increased H-2/CO ratio in the GXL phase. At identical operating conditions, such enhancements are not seen in the case of bidentate ligands wherein electronic effects likely exert more influence on the n/i ratio. (C) 2018 Elsevier Ltd. All rights reserved.