History of Catalytic Converter

Catalytic Converter is a triumph worth 30 points: "Complete the catalyst from the Master difficulty "Vox Obscura" Exotic quest."

How to complete

1. Own Dead Messenger and run the Master version of the Vox Obscura exotic mission, which carries the catalyst for the weapon (see Dead Messenger Catalyst).
2. The catalyst drops from a chest opened before the mission ends. A Bungie forum answer notes you must wait for the ending dialogue to finish so the mission actually completes; the triumph is awarded at completion, not at the chest.
3. Players on the Bungie forums report several bugs (catalyst dropped but no triumph, or the reverse). If it fails to pop, rerun the mission and let the end dialogue finish.

Search results describe it as a Season 16 triumph under the "Kill the Messenger" Legend entry; that was a search snippet, not a page I opened, so it is unconfirmed.

Rewards

30 triumph points and the Dead Messenger catalyst.