Fertilizer manufacturers commonly employ the Haber-Bosch (HB) technique to produce ammonia (NH3) to be used as a fertilizer for agriculture – a process that consumes 1-2% of global energy. The HB process involves first separating nitrogen (N2) from air, then breaking the very stable nitrogen-nitrogen bond, and finally combining these atoms with hydrogen to form NH3. Moreover, ammonia production requires huge capital investments for reactors operating at high pressure and temperature, baseload power to keep the process running continuously, and distribution infrastructure to ship the resulting chemicals around the world to agricultural fields. Ammonia can also be used as a fuel in fuel cells or internal combustion engines for both stationary and transportation applications. Small-scale reactors could enable distributed ammonia production closer to the consumer.
Project Innovation + Advantages:
The Colorado School of Mines will develop a membrane reactor concept to synthesize ammonia at ambient pressure. In traditional ammonia production processes, nitrogen (N2) and hydrogen (H2) compete for identical catalyst sites, and the presence of each inhibits the other, with the overall rate reflecting a compromise. The team proposes decoupling and independently controlling the N2 and H2 dissociation by dedicating one side of the composite membrane to each. In this way, the catalysts may be individually optimized. Highly effective catalysts have been previously demonstrated for H2 dissociation, and the team's focus will be on exploring early transition metals which have shown great promise as catalysts for N2 dissociation. When perfected, this technology will allow the production of ammonia at ambient pressure, reducing the scale and number of steps required in the process. This method is also an improvement over electrochemical processes, which have a more complicated design and reduced efficiency due to the need for an external voltage.