- odor insulation (simple and straightforward, read my analysis below and the conclusion)
- odor-blocking insulation could also be a close equivalent to thermal insulation but blocking and insulation seems redundant, one doesn't say heat-blocking insulation.
- odor-proof/-ing (first proposed by Andrew Leach in one of the first comments, proposed as odor-proofing in DjinTonic's answer above (+1 for this))
- odor-tight (my reply to Andrew's comment)
The topic raised interesting comments, some of which pertaining to science (unexpected, but a pleasant surprise).
So here is some further analysis, please do comment as I'm sure the topic can raise more discussion.
An odor is the result of the interaction between molecules having certain properties and olfactive sensors, and their subsequent analysis/processing. Note that these molecules may be detected in other ways such as with a chromatograph, spectrograph, etc but with such instruments they will not produce an odor.
Odors do not travel by conduction nor radiation, but by convection (the air is the carrier), they are not a form of energy. They ultimately travel by air (though other gazes may work and odor can pass through thin solids - membranes, plastic films, porous materials...)
Thermal pertains to heat. Heat, as sound, results from the vibration/interaction between molecules and/or atoms, it is not dependent on the chemical nature of the molecules themselves (nitrogen N2 has no odor but can transport heat or heat be created from it; at the same time, quantitatively speaking, some molecules or atoms may contribute to produce different amounts of heat depending on their nature).
Heat is a form of energy and may be used to produce work. It can be transferred by convection, radiation or conduction. Heat can be quantified.
Sound is a vibration, carried by a gaz, a solid or a liquid, and as for odor, has be received by a sensor and be further processed/analyzed to be interpreted as a sound (but note that sounds may exist even if not received by a sensor or be processed or analyzed, there are sounds one may not perceive or be aware off, yet they can exist). Sound can't be quantified by itself (though one says loud or soft sound, these are not quantities) unless a physical quality is added: e.g. sound pressure. In sound pressure, sound is a noun used as an adjective.
Conclusion: despite differences (semantically, grammatically, physically, and from a chemical point of view), heat (thermal), sound and odor all share the fact that they can be isolated from a receiver. Hence odor insulation seems to be a logical equivalent (semantically speaking) to thermal and sound insulation, but still not the grammatically speaking equivalent to thermal insulation: from that perspective it is closer to sound insulation.