SO 2 /NO 2 Separation Driven by NO 2 Dimerization on SSZ-13 Zeolite Membrane.

The molecular state is crucial for precise gas separation using a zeolite membrane, yet the state control remains a big challenge. Herein, we report a NO 2 dimerization facilitated high performance SO 2 /NO 2 separation on a SSZ-13 zeolite membrane. The NO 2 dimerization is triggered by temperature and pressure to form N 2 O 4 with big molecular size, and N 2 O 4 diffusion into the zeolite pore is inhibited on the basis of size exclusion, leading to high separation selectivity. Consequently, SO 2 rather than NO 2 preferentially permeates through the SSZ-13 membrane with a high SO 2 permeance of 2 × 10 -7 mol m -2 s -1 Pa -1 and high SO 2 /NO 2 separation factor of 22, ∼50-fold of that measured without dimerization. The dimerization effect for SO 2 /NO 2 separation prevails in other small-pore zeolites such as NaA. This advanced function is revealed through membrane separation using single and mixture gases.