(281a) On the Development of a Novel Pressure Swing Reactor for the Production of Ammonia

It has always been desirable to carry out reaction and separation in the same vessel.  The concept of a pressure swing reactor that can do reaction and separation in the same vessel has been around for several decades. However, this concept has yet to be commercialized, although several patents have been issued and some novel approaches have been tested at various scales.

A pressure swing reactor combines a pressure swing adsorption (PSA) process and catalytic gas phase reaction in such a way that a higher conversion can be achieved usually via Le Chatelier's principle. The difficulty is to find a suitable adsorbent that operates at or near the conditions of the catalytic reactor, i.e., at high temperature and pressure. High pressure is conducive to adsorption, but high temperature is not. In fact, most adsorbents are regenerated at temperatures far below the conditions of a catalytic reactor. Nevertheless, there are some catalytic systems that present an excellent opportunity for the design of a pressure swing reactor. The synthesis of ammonia from hydrogen and nitrogen is one such system.

Process simulations of a pressure swing reactor have shown that very high conversions can be obtained by using an adsorbent that reversibly adsorbs ammonia at high temperature by carrying out a relatively simple pressure swing cycle. The goal of this work is to experimentally validate the simulation results. For this purpose a bench-scale pressure swing reactor has been set-up and is currently being utilized to study the conversion of hydrogen and nitrogen into ammonia using a commercial catalyst and in the absence and presence of an adsorbent. This presentation will present the latest results obtained from this effort.