Zeolite ZSM-23 and aluminophosphate molecular sieve $AlPO_4-11$ were synthesized and the diffusion characteristics of cyclohexane, cyclohexene and cyclohexadienes in ZSM-23 and $AlPO_4-11$ were investigated.
Diffusion coefficient increased in the order cyclohexane, 1,4-cyclohexadiene, cyclohexene, 1,3-cyclohexadiene. The difference in diffusion characteristics is interpreted in terms of the unique pore size and shape of ZSM-23 and $AlPO_4-$-11 and the subtle difference in size and shape of the diffusing molecule.