Pyrimidine-bridged organoalkoxysilane membrane for high-efficiency CO₂ transport via mild affinity

A novel pyrimidine-bridged organoalkoxysilane precursor, 4,6-bis(3-triethoxysilyl-1-propoxy)-1,3-pyrimidine (BTPP), was synthesized via a platinum-catalyzed reaction and subsequently a BTPP membrane was developed via a sol-gel process. This new membrane exhibits great potential for improved CO₂separation compared with common amine-functionalized organosilica membranes. Possible CO₂transport mechanisms across amine-functionalized organosilica membranes were explored by comparing the CO₂sorption behaviors of organoalkoxysilane materials with both strong and mild affinities. The results showed that a membrane with strong affinity to CO₂does not lead to a superior CO₂separation capability. Hence, the concept of a “mild-affinity membrane” was proposed, which describes membranes with intermediate-to-low CO₂binding energy that exhibits an improved level of CO₂transport efficiency. The concept of a mild-affinity membrane offers the development of technological innovation leading to the realization of highly efficient CO₂separation membranes.