Plasma catalytic ammonia synthesis: state of the art and future directions

Abstract

This review describes the history and development of ammonia synthesis from its discovery to the early development of the Haber-Bosch process to the current use of plasma catalysis as an alternative to the possible process decentralization of this essential commodity. Proposed reaction mechanisms to-date for vacuum and atmospheric pressure discharges are summarized and discussed. The use of different discharges and materials employed as catalysts as well as the observed interactions between the plasma and the catalyst that can modify and activate the catalytic surface and the possible effects of the catalyst on plasma are herein summarized. Moreover, important differences between thermal catalysis and plasma catalysis are contrasted. It is intended that this review can also help to develop an understanding of the current knowledge and gaps for the ammonia synthesis through plasma catalysis with an emphasis on the challenges presently faced.

Enhancement of the Yield of Ammonia by Hydrogen‐Sink Effect during Plasma Catalysis

“…One emerging understanding, common to the investigated plasma scenarios, is the diminished importance of N 2 dissociation to determine ammonia formation rates compared to thermal catalysis. Instead, other reaction steps are bound to emerge as the key to control the catalyst performance …”

“…Instead, other reaction steps are bound to emerge as the key to control the catalyst performance. [27] The present work aims to further contribute towards the understanding of catalyzed ammonia formation by studying the reaction under a sub-atmospheric pressure RF plasma. These conditions allow us to focus on the role of atomic plasma species, which may be difficult to isolate at DBD conditions.…”

Plasma-driven catalysis: green ammonia synthesis with intermittent electricity

“…Extensive historical accounts can be found in other reviews. 82,84,90,141,261 The aim of this section is to show how recent insights in mechanisms can aid in the development of the field. The energy efficiency and conversion for various plasma reactor types are compared, describing the state of the art.…”

“…182,187,188,[190][191][192]194 In some cases, the reported units have been converted to g-NH 3 kW h −1 for the energy yield, and ppm for the ammonia concentration. We refer the reader to the recent review of Carreon 261 37.9 g-NH 3 kW h −1 . 165 Hereafter, plasma reactors for ammonia synthesis from H 2 and N 2 are discussed.…”

Ammonia Synthesis by Pressure Swing of N₂–H₂ Nonthermal Plasma

“…Ammonia is industrially one of the most important compounds and consumes huge amount of energy in its production process. erefore, the importance of chemical conversion of electric power to synthesize ammonia by plasma technology is increasing signi cantly (Bogaerts and Neyts, 2018;Peng et al, 2018;Carreon, 2019;Mehta et al;2019;Wang et al, 2019;Patil et al, 2020).…”