Selectoxo Process for Final Purification

For the conversion of CO into CO2 and H2, most ammonia plants, use a combination of two shift conversion steps, a High Temperature and a Low Temperature step. The CO content is decreased from about 10-12% (dry gas base) to approximately 0.2-0.4% (dry gas base) (IPTS/EC, 2007 p.41).

An energy efficient option is to add the Selective Catalytic Oxidation (Selectoxo) process after the Low Temperature Shift converter. When compared to other oxidation processes, the Selectoxo provides improved energy efficiency as it significantly reduces the CO slip to about 0.03%, improves process flexibility, and increases the throughput when revamped. The plant throughput can be increased by 1.5-2.0% (Maxwell, 2004 p.156). To achieve the selective oxidation, a precious-metal catalyst is used at 40-135oC. The CO2 formed adds only slightly to the load on the downstream CO2 absorption system (Ullmann’s, 2011 p.185).

Development Status Products

Selectoxo Process for Final PurificationCosts & Benefits

Parent Process: Shift Conversion
Energy Savings Potential
CO2 Emission Reduction Potential

Not available. 

Selectoxo Process for Final Purification Reference Documents

Reference Document on Best Available Techniques for the Manufacture of Large Volume Inorganic Chemicals - Ammonia, Acids and Fertilisers

Prepared by the Institute for Prospective Technical Studies of European Commision, this document provides detalied information on Best Available Technologies applicable to Ammonia production – as well as on the production of Acids and Fertilizers.  

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