C2 adsorption in zeolites: in silico screening and sensitivity to molecular models

Abstract

Selective zeolitic frameworks for adsorptive separation of ethane and ethylene are identified using molecular modeling with improved force fields.

Design of organic structure directing agents to guide the synthesis of zeolites for the separation of ethylene–ethane mixtures

“…The fractions of variance covered in the two principal coordinates are 0.35 and 0.13. framework was rst identied in a heteroatom-stabilized AlPO 4 zeolite-analog material. 31 The choice of all-silica target zeolites DFT and ACO for selected ethylene adsorption, and NAT and JRY for selected ethane adsorption, was based upon the work by Shah et al 7 In that study, these frameworks scored best in an efficient highthroughput screen using efficient simulation algorithms and accurate molecular force elds. The performance measure of the zeolites for ethane-ethylene separations was the product of the loading of the strongest adsorbing species, Q, and the logarithm of the selectivity towards this species, S. The latter is dened as S…”

“…While the impact of the presence of defects such as silanol or cation impurities is briey mentioned in ref. 7, the screening was performed on the allsilica materials and hence our OSDA design effort was also directed toward the all-silica zeolites.…”

“…5 This has motivated a number of computational screening studies to identify zeolites that selectively adsorb ethylene versus ethane or ethane versus ethylene. 6,7 In the latter study, Shah et al identied a number of promising zeolite frameworks for ethylene-ethane separation using a detailed molecular analysis. 7 The zeolites identied are predicted to have a high selectivity and adsorption capacity in their all-Si forms.…”

“…6,7 In the latter study, Shah et al identied a number of promising zeolite frameworks for ethylene-ethane separation using a detailed molecular analysis. 7 The zeolites identied are predicted to have a high selectivity and adsorption capacity in their all-Si forms. All-Si zeolites are less polar than their Al-containing forms and therefore generally exhibit a lower adsorption enthalpy, which can provide a practical advantage by reducing the regeneration energy needed in the desorption step of the separation.…”

“…[14][15][16][17] In the present paper, we report our design efforts towards OSDAs for templating all-Si zeolites with the DFT and ACO frameworks for ethylene adsorption and the NAT and JRY frameworks for ethane adsorption. These are the frameworks predicted to be most efficient in the work of Shah et al 7…”