Precise molecular sieving of ethylene from ethane using triptycene-derived submicroporous carbon membranes

Replacement or debottlenecking of the extremely energy-intensive cryogenic distillation technology for the separation of ethylene from ethane has been a long-standing challenge. Membrane technology could be a desirable alternative with potentially lower energy consumption. However, the current key obstacle for industrial implementation of membrane technology is the low mixed-gas selectivity of polymeric, inorganic or hybrid membrane materials, arising from the similar sizes of ethylene (3.75 angstrom) and ethane (3.85 angstrom). Here we report precise molecular sieving and plasticization-resistant carbon membranes made by pyrolysing a shape-persistent three-dimensional triptycene-based ladder polymer of intrinsic microporosity with unparalleled mixed-gas performance for ethylene/ethane separation, with a selectivity of similar to 100 at 10 bar feed pressure, and with long-term continuous stability for 30 days demonstrated. These submicroporous carbon membranes offer opportunities for membrane technology in a wide range of notoriously difficult separation applications in the petrochemical and natural gas industry.

Automated summary

The use of membrane technology made of polymeric, inorganic or hybrid membrane materials is a desirable alternative to the energy-intensive cryogenic distillation technology for ethylene/ethane separation. However, the low mixed-gas selectivity of current membrane materials is a major obstacle. This study presents the development of precise molecular sieving and plasticization-resistant carbon membranes with unparalleled performance for ethylene/ethane separation, offering great potential for challenging separation applications in the petrochemical and natural gas industry.