Thermodynamic-Kinetic Synergistic Separation of Light Olefins/Paraffins in Post-Synthetically Modified Small-Pore...

The search for selective microporous adsorbents in light olefin/paraffin separations presents many challenges in replacing current energy-intensive cryogenic distillation processes. Here, it is demonstrated that modified acidic intermediate-silica small-pore zeolites, for example, the proton form of zeolite rho with a Si/Al ratio of 3.3 (H-rho), using ammonium fluoride/hydrogen peroxide etching followed by phosphorus loading, can decisively improve ethylene/ethane and propylene/propane separation performances based on the thermodynamic-kinetic synergistic mechanism. 2.0 (I) and 1.2 (II) weight% phosphorus loadings on etched H-rho afford steady-state ethylene and propylene productivities (≥99.5%) of 28.8 and 33.7 L kg^-1 under dynamic breakthrough conditions using equimolar ethylene/ethane and propylene/propane mixtures, respectively. Also, a combination of these two loadings in a dual-layer configuration of I on top and II on bottom provides a steady-state propylene productivity (≥99.5%) of 23.5 L kg^-1 and a recovery yield of 81% under the same conditions using an equimolar four-component (ethylene/ethane/propylene/propane) mixture. This study opens a new avenue for the design and development of zeolite molecular sieves for multicomponent light olefin/paraffin separations.