(382bc) Novel Ruthenium-Based Catalysts for Ammonia Synthesis

Presently, the world is pushing for new pathways to make necessary chemicals with a reduced environmental impact. One option for improvement is the ammonia synthesis reaction, as it accounts for approximately 2% of the world’s CO₂ emissions. The main issue for ammonia synthesis is the harsh operating conditions caused by the thermodynamic limitations and iron-based catalysts that are employed industrially. To counteract the thermodynamic issues, new membrane and pressure-swing adsorption reactors are being tested to remove the produced ammonia as it is created rather than after the catalyst bed. However, due to the temperature and pressure limits of these reactors, ruthenium-based ammonia synthesis catalysts should instead be used.

The current drawback of ruthenium, though, is the cost in comparison to iron. Although it is much more active than iron, most ruthenium-based catalysts use about 5 wt.% ruthenium making the cost per ton of ammonia too high for wide-spread commercialization. To combat this, we produced new, promoted 1 wt.% ruthenium catalysts supported on praseodymium oxide. These catalysts, once optimized, could produce comparable amounts of ammonia to a typical industrial iron-based catalyst, but could operate at much lower temperatures and pressures, as needed. Further experimentation permitted us to determine the role of the promoters used and the mechanism for the process, as well as discover a few beneficial promoters that had not been previously explored for ammonia synthesis. Overall, this work has helped to create a new possibility for non-iron-based ammonia synthesis.

Research Interests

My research interests include improving both catalytic and non-catalytic processes for alternative energy production and chemical energy storage. In particular, I am interested in using novel heterogeneous catalysts to improve the stability, selectivity, cost and energy efficiency of new and existing processes.