There is little opportunity to improve further the Ostwald nitric acid process. The overall efficiency of ammonia conversion into acid is in the range of 94-96%. The process is self-sufficient in energy supply and can even export steam. Up to 80% of platinum catalyst losses can now be recovered. Capital investments were significantly reduced by the development of high-pressure absorption and with the design of efficient and reliable compressors and expanders. Economies of scale improve little for single-train units with capacities above 1,000 tonnes per day.

The trends seen in nitric acid production are as follows:

• A tendency from low- to medium- or high-pressure processes.
• Capacities should continue to increase with single train plants; these plants produce up to and over 2,000 tonne of nitric acid per day.
• Advanced energy recovery and a more efficient use of raw material by using improved methods of calculation are likely to lead to reduced investment costs and thus lower overall production costs.
• Enhanced focus on low NOx and N₂O emissions.
• Further research in catalyst development both for the ammonia oxidation step as well as for abatement.

A pattern of incremental improvements in the technology may be expected to continue, but there is little expectation of a significant breakthrough in capital investment and production costs.

Links to related IFS Proceedings and recordings

771, (2015), Modern Plasma Technology for Nitrogen Fixation: New Opportunities?, R Ingels, D Graves, S Anderson, R Koller

803, (2017), Changes, challenges, and opportunities in fertiliser-manufacturing processes: A personal review and outlook, J G Reuvers

861, (2021), How Green Ammonia Feed and State of the Art Nitrous Oxide Abatement Contribute to Green Nitric Acid Production, D. Birke, B. Mielke

Update on progress developing plasma technology for nitrogen fixation, M. Nyvold, N2 Applied, Webinar recording, 2021.