Case studies · Submarines · enclosed-space life support
Regenerating palladium carbon monoxide filters for the Indian Navy
Carbon monoxide filters for naval submarines use palladium-impregnated carbon. Palladium is a costly noble metal, so treating spent filters as consumables carries a heavy recurring cost. Suracsh and DRDO developed a procedure to recover the metal and restore it to a catalytic state.
Partner: Indian Navy, with DRDO
The problem
Carbon monoxide is colourless, odourless and tasteless, and it is dangerous at concentrations far below anything a person can detect. In an enclosed, occupied space with no ventilation to outside air, that combination is the hazard.
CO is removed from enclosed spaces using palladium-impregnated carbon. The palladium is what does the work — and it is an expensive noble metal.
Replacing spent filters outright meant buying the palladium again every cycle. The Indian Navy wanted the used CO filters from its submarines regenerated instead, to bring the operating cost down.
What we did
Suracsh took up the regeneration project and worked with the DRDO — the Defence Research and Development Organisation.
Together they developed a proprietary procedure to extract the spent noble metal and correct its oxidation state back to the catalytic state. Recovering the metal is only half the problem: palladium that is present but in the wrong oxidation state does not catalyse anything.
Outcome
The programme produced a regenerated filter, returned to service rather than replaced, with the palladium recovered from the spent unit.
The company records the regenerated filter as performing to the same standard as a new filter, and the customer as achieving a substantial saving against buying replacements.