High-pressure electrochemical promotion of ammonia synthesis over an industrial iron catalyst

The catalytic reaction of ammonia synthesis is of paramount importance in t he chemical industry, mainly for fertilizers production.(1,2) The reaction is equilibrium limited and is favored by low temperatures and high operatin g pressure. Since the pioneering work of Haber and Bosch the industrial amm onia synthesis is carried out over potassium-promoted Fe catalysts at press ures up to 300 bar. Here we show that the catalytic activity of state-of-th e-art fully promoted industrial ammonia synthesis catalysts can be enhanced by up to 1300% by interfacing the catalyst with a proton conductor (CaIn0. 1Zr0.9O3-alpha) and electrochemically supplying protons to the catalyst sur face. The rate increase is up to 6 times larger than the rate of proton sup ply to the catalyst. This is the first demonstration of the effect of elect rochemical promotion, or non-Faradaic electrochemical modification of catal ytic activity (NEMCA)(3-9) using a commercial catalyst and under high (50 b ar) pressure. It is also the first demonstration of scale-up of an electroc hemically promoted catalytic reactor as 24 electrically connected catalyst pellets were used. The results could in principle lead to a substantial dec rease in the operating temperature and pressure of ammonia synthesis reacto rs.