Anion controlled pore size on titanium silicate molecular sieves
Christopher Lin, PhD student in Chemical Engineering
ETS-4, a structural relative of the mineral zorite, was the first synthesized mixed coordination octahedral/tetrahedral molecular sieve. We report that by controlling the anionic content of ETS-4 analogs, the pore size of such materials (Halogen Containing Zorite or HCZ) can be systematically and rigorously tuned. Stabilized with cations such as barium, these new zorite-like materials can be prepared and activated over a wide temperature regime. Clean resolution of molecules of similar size such as O2/Ar and N2/CH4 are possible with HCZ by controlling the pore size with synthesis and ion-exchange, rather than thermally-induced structural contraction. For mixed coordination molecular sieves, this represents the next step in “absolute control” of zeolite pore size and a new dimension in the concept of molecular sieving.
ETS-4, a structural relative of the mineral zorite, was the first synthesized mixed coordination octahedral/tetrahedral molecular sieve. We report that by controlling the anionic content of ETS-4 analogs, the pore size of such materials (Halogen Containing Zorite or HCZ) can be systematically and rigorously tuned. Stabilized with cations such as barium, these new zorite-like materials can be prepared and activated over a wide temperature regime. Clean resolution of molecules of similar size such as O2/Ar and N2/CH4 are possible with HCZ by controlling the pore size with synthesis and ion-exchange, rather than thermally-induced structural contraction. For mixed coordination molecular sieves, this represents the next step in “absolute control” of zeolite pore size and a new dimension in the concept of molecular sieving.
