An ultrahigh permeance and CO2 selective membrane of organosilica-based coordination polymer tailored via nickel crosslinking

A novel concept that involves the use of an organosilica-based coordination polymer was successfully implemented to create a high-performance nickel-dope-hindered tertiary amine-ring structure in tris-(trimethoxysilyl propyl) isocyanurate silane (TTPI) membranes for CO2/N2 separation. The interfacial crosslinking was developed from nickel (Ni) metal sites that served as Lewis-acid molecules with amine moieties from isocyanurate-ring as Lewis-base molecules. We discovered that high levels of nickel/amine (Ni/N) mole ratios improves metal affinity, thus enhancing the structural rigidity, surface area (from 30.1 to 308 m2 g−1), and improves the CO2 adsorption capacity of Ni-TTPI membranes, which results in high levels of gas permeance on the order of Ni-TTPI 0.25 > Ni-TTPI 0.125 > TTPI. In addition, we found that the CO2 separation performance of Ni-TTPI membranes is also influenced by nickel-amine coordination and that Ni(OH)2 facilitates adsorption at a calcination temperature of 250 °C. An ultrahigh CO2 permeance of 3 × 10−6 mol m−2 s−1 Pa−1 (8,960 GPU) and a CO2/N2 permeance ratio of 40 was achieved in a CO2/N2 (1/9) mixture of Ni-TTPI at the highest Ni/N ratio of 0.25 mol mol−1 due to precise tuning of the pore size, increased microporosity, and the establishment of Ni(OH)2, which results in lower activation energy for CO2, which indicates great potential for permeation.