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US Navy submarines have used Hopcalite catalyst (MnO2, CuO) for over 30 years to oxidize carbon monoxide, hydrogen, and many trace organic species. During that time, the material has been manufactured by the same company, and the performance of fresh Hopcalite has never shown significant variation. Recently, a new lot of Hopcalite was tested and found to be 300% more active toward one specific refrigerant than measured in previous lots. In life support applications, unexpectedly high activity can generate hazardous products that endanger crew and equipment. This paper will describe and interpret the tests performed by the Naval Research Laboratory and Naval Surface Warfare Center to investigate different Hopcalite samples.

The United States Navy uses the catalyst HOPCALITE for removal of carbon monoxide and hydrogen from the enclosed atmosphere of its submarines. At temperatures higher than those required for CO and H2, HOPCALITE also catalyses the oxidation of many organic substances. In some cases, these reactions produce toxic byproducts and/or catalyst poisoning. The activity of HOPCALITE varies greatly toward seemingly similar species. This work presents a model for predicting the activity of HOPCALITE with a linear equation using simple physical and chemical properties of the reacting species. Many parameters were evaluated. The model uses only three parameters to fit the observed reactivities of 51 chemicals. A final correlation coefficient (r2) of 0.80 is achieved.