The separation of propylene (C3H6) from ethylene (C2H4) is one of the most vital processes to obtain high-purity C2H4 in the petrochemical industry, which is commonly limited by the insufficient C3H6 uptake or poor C3H6/C2H4 selectivity due to the weak C3H6 binding affinity. Herein, a low-cost cobalt formate framework (termed as CoFA) was synthesized up to 40 g for efficient C3H6/C2H4 separation. CoFA with multiple accessible Oδ- sites and contracted zigzag pore channels provides a unique single-molecule C3H6 nanotrap with benchmark high C3H6 adsorption affinity. The C3H6 uptake at 0.01 bar reaches as high as 59.4 cm3 cm−3, ranking second among the materials in the context of C3H6/C2H4 separation. Breakthrough experiments confirm its excellent separation capacity for equimolar C3H6/C2H4 mixtures. The separation performance is retained under 5 cycles and under humid conditions. Theoretical calculations reveal that the perfectly size-matched pore cavities combined with multiple hydrogen bonding sites enable this single-molecule C3H6 nanotrap to maximize the C3H6 binding affinity. The shaping properties of CoFA were investigated by using four different binders with PES as the best one to shape CoFA with retained capacity and selectivity.
Read full abstract