Design of Organic Structure-Directing Agents for the Controlled Synthesis of Zeolites for Use in Carbon Dioxide/Methane Membrane Separations.

One strategy to mitigate global warming is carbon capture and sequestration. Membrane separation is one promising approach to separation of CO from feed streams. Here we report the investigation of four zeolites that have been predicted to be effective at separating CO from methane, but which have not to date been synthesized experimentally as membranes. Using an in silico de novo design procedure, we identify organic structure-directing agents (OSDAs) that are predicted to aid the synthesis of these zeolites. Using a genetic algorithm approach, we designed OSDAs for zeolites for which no purely siliceous form is known, and we also designed OSDAs for predicted zeolites. Stabilization energies of the best OSDAs designed for the zeolites GIS, ABW, and predicted zeolite 8198030 lie within -8 to -12 kJ/(mol Si), in the range of values for other known OSDAs. Stabilization energies of the OSDAs designed for predicted zeolite 8186909 are -16 kJ/(mol Si), comparable to the best known OSDAs for any zeolite. The OSDAs reported here may lead to zeolites that could enable a practical separation of CO from methane.