Some of the aluminophosphate molecular sieves are small pore materials. A1P04-20, like
its zeolite analogue sodalite, is a small-pore molecular sieve that admits only water. A1PO4-14 and A1PO4-33 adsorb xenon (0.40 nm) but not n-butane (0.43 nm). AlP04-17 and
AlP04-18 have a slightly larger pore size of 0.46 nm, adsorbing n-paraffins
but excluding isoparaffins.