Foundations of plasma catalysis for environmental applications

Abstract

Plasma catalysis is gaining increasing interest for various applications, but the underlying mechanisms are still far from understood. Hence, more fundamental research is needed to understand these mechanisms. This can be obtained by both modelling and experiments. This foundations paper describes the fundamental insights in plasma catalysis, as well as efforts to gain more insights by modelling and experiments. Furthermore, it discusses the state-of-the-art of the major plasma catalysis applications, as well as successes and challenges of technology transfer of these applications.

Sustainable Hydrogen and Ammonia Technologies with Nonthermal Plasma Catalysis: Mechanistic Insights and Technoeconomic Analysis

“…In general, catalyst precursors must be calcined as part of the late-stage catalyst synthesis strategy to remove precursor impurities, but the conventional calcination process demands a high-temperature requirement, which would inevitably cause some active metals to aggregate and some undesirable deactivation . Catalyst preparation using plasma technology has led to high active metal dispersion and good metal–support interaction . In comparison to the traditional methods, the plasma technology for making catalysts has several benefits, including a lower energy requirement, quick preparation periods, highly dispersed active species, increased catalytic activity, and a longer lifetime.…”

“…Plasma catalysis for gas cleaning (i.e., removal of undesirable volatile organic compounds (VOCs) and NO x from gas streams) is a relatively mature concept, ,, with numerous commercial products in the market. However, the applications of plasma catalysis for gas conversions such as CO 2 utilization, hydrogen production, and production of high-value synthetic fuels or hydrogen storage (e.g., ammonia and methanol) via a number of possible reactions (i.e., dry methane reforming, CO 2 methanation, methane pyrolysis, ammonia decomposition and synthesis, CO 2 hydrogenation to methanol and dehydrogenation reactions) are still undergoing research and laboratory-stage development . Although the application of plasma catalysis for gas conversion is still in its infancy, the potential of using plasma for sustainable environmental applications has spurred many recent articles and reviews in recent years.…”

Incorporation of a Metal Catalyst for the Ammonia Synthesis in a Ferroelectric Packed-Bed Plasma Reactor: Does It Really Matter?

“…This controversial scenario in relation with the role of metal particles in the plasma-driven ammonia synthesis reactions rises critical questions about the possible links between surface and plasma mechanisms and the extent by which metals may affect the plasma properties and behavior. − In other words, although adding a metal catalyst to the packed-material could promote catalytic-driven processes, this might also modify the electric field in the immediacy of the metal nanoparticles, alter the characteristics of the discharge, and likely affect the reaction mechanisms in the plasma phase. A first objective of the present work, beyond the existence of possible catalytic effects, is to determine the occurrence of plasma effects induced by the presence of metal nanoparticles in the packed bed and how these effects may affect the efficiency of the ammonia synthesis process.…”

Interrogation of the Plasma-Catalyst Interface via In Situ/Operando Transmission Infrared Spectroscopy

“…However, the complexity of plasma-phase interactions with reactive surfaces has resulted in many empirical studies on the performance of different catalytic materials with limited information on the fundamental elementary processes occurring at the plasma− catalyst interface. 2,21 Therefore, a transition toward operando and in situ characterization approaches can advance the field by directly observing how plasma stimulation affects the evolution of surface speciation. Of additional importance is the need for simple and inexpensive plasma modules capable of interfacing with existing and commonly utilized in situ/operando characterization techniques.…”

“…Low-temperature plasma-induced interactions have been exploited for a wide range of applications including medical treatments, − pollutant removal, , electronics manufacturing, , material synthesis, ,,− and heterogeneous catalysis. ,− Plasma-assisted catalysis has seen a significant growth in research activity over the past decade, primarily motivated by the ability to activate stable molecules (e.g., CH 4 , ,− CO 2 , ,− ,− and N 2 ,− ) at relatively low temperature through electrical energy input. However, the complexity of plasma-phase interactions with reactive surfaces has resulted in many empirical studies on the performance of different catalytic materials with limited information on the fundamental elementary processes occurring at the plasma–catalyst interface. , Therefore, a transition toward operando and in situ characterization approaches can advance the field by directly observing how plasma stimulation affects the evolution of surface speciation. Of additional importance is the need for simple and inexpensive plasma modules capable of interfacing with existing and commonly utilized in situ/operando characterization techniques.…”