Iron-Based Catalysts for the High-Temperature Water–Gas Shift (HT-WGS) Reaction: A Review

Abstract

This article critically reviews the literature on iron-based catalysts for the high-temperature water–gas shift (HT-WGS) reaction. The reaction mechanism, reaction intermediates, rate-determining step, kinetics, active site, and promoters are covered. Unlike the low-temperature water–gas shift (LT-WGS) reaction by Cu/ZnO catalysts that has received intensive analysis with modern in situ and operando spectroscopy and DFT studies, the corresponding HT-WGS reaction by Fe-based catalysts still lacks a fundamental understanding because of the absence of modern catalysis studies of this important catalytic system. Given the role of the WGS catalysts on production of H2 for a hydrogen economy, it is imperative that the fundamental molecular-level understanding of the HT-WGS catalyst be advanced.

The Effect of Copper Addition on the Activity and Stability of Iron-Based CO2 Hydrogenation Catalysts

“…Although some reduction should be expected due to the presence of H 2 , there does not appear to be a correlation between the increase in the FCC phase and an increase in catalytic activity for CO 2 hydrogenation. This result differs from the modeling [24,25,26,27,28,29] precedent, which uses the metallic FCC phase as a catalytically active site in Fe x Cu y catalyst. In the highest performing catalyst, 90Fe10Cu/K, there is no evidence of the metallic phase.…”

“…Some modeling efforts of CO 2 hydrogenation on the iron copper intermetallic (100) phase support the hypothesis that small amounts of copper will be beneficial to the system [24]. There is also extensive work on how catalysts change as a result of exposure to syngas conditions [25,26,27,28,29], but there is very little characterization work being done on FeCu/K catalysts in CO 2 hydrogenation conditions.…”

The Synergy Effect of Ni-M (M = Mo, Fe, Co, Mn or Cr) Bicomponent Catalysts on Partial Methanation Coupling with Water Gas Shift under Low H2/CO Conditions

“…It is reported that a variety of transition metals has exhibited their distinct methanation activity, such as Ni, Ru, Rh, Pd and Pt [9]. Meanwhile, another group of transition metals performs well in WGS, including Mo [10], Fe [11], Co [12], Mn [13,14] and Cr [15]. However, for the specific WGS plus methanation unit, it is necessary to develop a novel catalyst, which can simultaneously catalyze WGS and the methanation reaction.…”

Dynamics of CrO3–Fe2O3 Catalysts during the High-Temperature Water-Gas Shift Reaction: Molecular Structures and Reactivity

“…Newsome reviewed the catalysis literature up to 1980, 4 Rhodes et al reviewed the literature up to 1995, 1 Ladebeck and Wagner provided a review up to 2003 with an emphasis on fuel cell applications, 7 Ratnasamy and Wagner reviewed recent developments up to 2009, 2 and Zhu and Wachs focused on iron-based catalyst research up to 2016. 8 In recent years, there has also been an interest in developing Cr-free iron oxide based HTS catalysts because of the toxicity of hexavalent chromium, but successful substitutes have still not be achieved. 9 This literature review will primarily focus on new characterization studies performed in the last two decades that provide new insights to the HTS chromium-iron oxide catalysts, but will also explore older, relevant publications if they contain additional insights.…”