Understanding and improving the modular properties of high-performance SSZ-13 membranes for effective flue gas treatment

High-performance tube-supported standard oil synthetic zeolite-13 (SSZ-13) membranes were prepared using low-temperature ozone calcination and modularized in different-sized permeation cells. The hydrophobic SSZ-13 membrane exhibited robust, marked CO2/N2 separation performances at a H2O vapor partial pressure of 10 kPa at 50 °C (CO2 permeance of 1.3 × 10−7 mol∙m−2 s−1∙Pa−1 and CO2/N2 separation factor (SF) of ca. 31.5). However, these intrinsic values were obtained at high feed flow rates, where the optimal recovery of CO2 molecules cannot be obtained. Thus, we correlated membrane (permeance and SF) and feed stream (Reynolds number) properties, finding that convective mass transfer from feed to outer membrane surface (Sherwood number) was described by the Reynolds number and cell dimensions. This further accounted for the CO2 molar flux and CO2/N2 SF. Based on this, we proposed critical parameters (comprising total feed flow rate and pressure, and characteristic module dimension) to describe the representative module properties of the recovery, purity, and process efficiency (PE) for CO2. Finally, the PE of the membrane unit was improved in double-stage configuration, yielding noticeable improvements in CO2 purity and PE at the slight expense of CO2 recovery. Crucially, the process-based module properties were well understood and predicted using the feed stream properties.