Described herein are compositions having an eight-membered monocyclic unsaturated hydrocarbon, methods and system to separate the eight-membered monocyclic unsaturated hydrocarbon at from a hydrocarbon mixture including additional nonlinear unsaturated C8H2m hydrocarbons with 4≤m≤8, by contacting the hydrocarbon mixture with a 10-ring pore molecular sieve having a sieving channel with a 10-ring sieving aperture with a minimum crystallographic free diameter greater than 3 Å and a ratio of the maximum crystallographic free diameter to the minimum crystallographic free diameter between 1 and 2, the molecular sieve having a T1/T2 ratio ≥20:1 wherein T1 is an element independently selected from Si and Ge, and T2 is an element independently selected from Al, B and Ga, the 10-ring pore molecular sieve further having a counterion selected from NH4+, Li+, Na+, K+ and Ca++.