An Evaluation of the Effect of Fluorinated Refrigerant, Siloxane and Associated Atmosphere Contaminant Compounds on the Performance of High and Low Temperature Carbon Monoxide / Hydrogen Oxidation Catalysts



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47th International Conference on Environmental Systems


A submarine’s atmosphere contains a complex mixture of compounds. Contaminants are produced from the running of the ships systems, off-gassing from materials, and chemical reactions occurring on-board. For reasons of toxicity or detrimental effects on equipment performance, maximum concentration limits have been set for many of these contaminants. The Royal Navy currently uses a high temperature oxidation catalyst to remove carbon monoxide and hydrogen from the submarine atmosphere. It has been proposed that the existing oxidation catalyst could be poisoned by typical submarine contaminants such as fluorinated refrigerant and siloxane compounds. A study has been undertaken to determine whether exposure to these contaminants adversely affects the performance of either the high temperature catalyst Moleculite® or its potential low temperature alternative, Sofnocat® 423. This work demonstrated that refrigerants R134a, R236fa and R1234ze did not adversely affect Sofnocat® 423. However, these refrigerants did have a detrimental effect on Moleculite®. R134a decreased the removal capability of Moleculite® from 91.8 % to 88.0 % for H2. R1234ze had a more significant effect on the catalyst, decreasing its removal capability from 90.6 % to 83.4 % for CO and from 89.4 % to 24.2 % for H2. Exposure tests to hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylpentasiloxane and the associated organo-silicon compound, trimethylsilanol had no discernable effect on Sofnocat® 423. Some minor effects were found on Moleculite® performance, for example, exposure to hexamethylcyclotrisiloxane reduced the oxidation of CO from 100.0 % to 95.9 % and H2 from 94.1 % to 89.0 %.


Timothy Taylor, QinetiQ, United Kingdom
ICES504: Management of Air Quality in Sealed Environments
The 47th International Conference on Environmental Systems was held in South Carolina, USA on 16 July 2017 through 20 July 2017


Submarine, Catalyst, Inhibition, Refrigerant, Siloxane