Separation of a binary mixture of ethylene and ethane by adsorption on Na-ETS-10

Abstract

Ethylene produced by steam cracking and thermal decomposition of ethane must be purified prior to use in the production of plastics, rubber and films. Ethane–ethylene separation is generally achieved by cryodistillation. The energy and equipment costs associated with ethylene purification could be significantly reduced by the development of alternative separation methods. Both modelling predictions for the binary adsorption of ethylene and ethane, and recent work investigating the adsorption of ethane and ethylene on the surface of Engelhard Titanosilicate-10 (ETS-10), a large-pored, mixed octahedral/tetrahedral titanium silicate molecular sieve, indicate that this molecular sieve might be an adsorbent capable of ethylene/ethane separations. However, the actual separation of a binary mixture of ethylene and ethane on ETS-10 has yet to be demonstrated. In this work, Na-ETS-10 was used to separate a mixture of ethylene and ethane (59% C 2H 4, 41% C 2H 6) from an industrial process stream with a measured binary bed selectivity for ethylene over ethane of approximately 5 at 25 °C and 1 atm. In a laboratory-scale demonstration, both high purity ethane and significantly enriched ethylene were produced, and the Na-ETS-10 adsorbent was regenerated for further separation cycles by both steam and microwave desorption, without degradation of the adsorbent or products.