A process concept that exploits CXLs to intensify hydroformylation reactions was recently demonstrated.[1]  When dense CO₂ is used to partially replace the excess substrate (1-octene) to create a CO₂-expanded liquid (CXL) phase, the 1-octene hydroformylation turnover frequency (~300 h^-1) and the selectivity towards the linear aldehyde (~90%) are significantly enhanced relative to the reaction in neat media. Further, these enhancements occur at mild pressures (~40 bar) and temperatures (60°C). Preliminary economic analysis indicates that near-quantitative (>99.8%) recovery of the Rh-based catalysts is essential for commercial viability.[2] Toward this end, soluble polymer supported bidentate phosphite ligands for hydroformylation of higher (> C₄) alkenes have been developed and evaluated.  The efficient separation and recycle of homogeneous rhodium catalyst complexes from reaction mixtures is attempted by using membrane filtration technology in a high-pressure filtration cell equipped with cross-linked asymmetric polyimide nano- and ultra- filtration membranes. Experiments with the catalyst complex dissolved in pure toluene revealed a Rh loss in the permeate of less than 1% while no P was detectable in the permeate. Similar measurements at actual hydroformylation conditions are ongoing. The effects of dissolved CO₂ (in the CXL media) on the solution viscosity and the permeate flux will be discussed. In addition, results on the recyclability and durability of polymer supported rhodium catalyzed 1-octene hydroformylation in CXLs will be presented.