Special Issue "Catalysts for Water-Gas Shift Reaction"

A special issue of Catalysts (ISSN 2073-4344).

Deadline for manuscript submissions: closed (30 June 2020).

Special Issue Editors

Prof. Dr. Panagiotis G. Smirniotis
Website
Guest Editor
Chemical Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221-0012, USA
Interests: use of molecular sieves as catalysts for refining applications; synthesis of smart materials; removal of nox and sox from mobile and stationary applications; photocatalytic decontamination of gaseous and aqueous streams from toxic organics; production of hydrogen; removal of carbon dioxide from high temperature processes; separations of biomolecules with molecular sieves-based processes
Dr. Devaiah Damma
Website
Guest Editor
Chemical Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221-0012, USA
Interests: nano materials synthesis; heterogeneous catalysis; catalytic oxidation of air pollutants; hydrogen production; catalytic abatement of nox; oxygenates from syngas; photocatalysis
Prof. Dr. Sibudjing Kawi
Website
Guest Editor
Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore
Interests: Applied catalysis; Catalytic membrane reactor; CO2 capture & utilization; Gasification & reforming; hydrogen & syngas
Special Issues and Collections in MDPI journals
Dr. Minghui Zhu
Website
Guest Editor
State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
Interests: heterogeneous catalysis, electrocatalysis, in situ spectroscopy

Special Issue Information

Dear Colleagues,

The majority of industrial H2 is currently produced by methane steaming reforming (MSR) followed by water-gas shift (WGS) reaction to control the H2/CO ratio and is employed in numerous applications such as ammonia synthesis, methanol synthesis, synthetic fuels, etc. Although there is much interest in developing sustainable H2 production from photocatalytic/electrocatalytic splitting of H2O and biomass reforming, production of H2 from fossil fuels (CH4, hydrocarbons and coal) will be around and expand for quite some time given its established technology and cost competitiveness. Currently, the WGS reaction is commercially performed in several stages with different catalysts to optimize the greater CO equilibrium conversion attained at lower temperatures because the reaction is exothermic and reversible. Commercially, the low-temperature WGS (LT-WGS) reaction is performed at ∼190−250 °C with a Cu/ZnO/Al2O3 catalyst, and the high-temperature WGS (HT- WGS) reaction is performed at ∼350−450 °C with a Cu promoted chromium-iron mixed oxide catalyst. There are also a variety of noble metal catalysts being developed and exhibit outstanding activity at low temperatures. The present special issue aims to cover recent research progress on water-gas shift catalysts for various temperature ranges.

Prof. Dr. Panagiotis G. Smirniotis
Dr. Devaiah Damma
Prof. Dr. Sibudjing Kawi
Dr. Minghui Zhu
Guest Editors

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Keywords

  • water-gas shift
  • hydrogen
  • carbon monoxide
  • characterization
  • mechanism
  • kinetics
  • surface science

Published Papers (8 papers)

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Research

Open AccessArticle
Water–Gas Shift Activity of Pt Catalysts Prepared by Different Methods
Catalysts 2020, 10(10), 1132; https://doi.org/10.3390/catal10101132 - 01 Oct 2020
Abstract
Platinum supported on ceria and zirconia was prepared through different preparation methods: Coprecipitation (CP), spray drying (SD), and flame spray pyrolysis (FSP). The catalysts were characterized by XRD, TPR, N2 adsorption, and H2 chemisorption, and the water–gas shift activity in the [...] Read more.
Platinum supported on ceria and zirconia was prepared through different preparation methods: Coprecipitation (CP), spray drying (SD), and flame spray pyrolysis (FSP). The catalysts were characterized by XRD, TPR, N2 adsorption, and H2 chemisorption, and the water–gas shift activity in the range 190–310 °C and initial stability at 300–310 °C were tested. Although the spray-dried Pt/CeO2/ZrO2 catalyst shows the highest initial activity, it deactivates rapidly at 300 °C and levels out at similar activity as the coprecipitated Pt/CeO2 and Pt/CeO2/ZrO2 within a few hours. Flame spray pyrolysis appears to be a promising preparation method concerning the stability of catalysts, although the initial activity is rather poor. High activity is related to high Pt dispersion, low reduction temperature, and small support particles. The support particle size is also much affected by the preparation method. Full article
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
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Open AccessArticle
Zn-Al Mixed Oxides Decorated with Potassium as Catalysts for HT-WGS: Preparation and Properties
Catalysts 2020, 10(9), 1094; https://doi.org/10.3390/catal10091094 - 21 Sep 2020
Cited by 1
Abstract
A set of ex-ZnAl-LDHs catalysts with a molar ratio of Zn/Al in the range of 0.3–1.0 was prepared using co-precipitation and thermal treatment. The samples were characterized using various methods, including X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), [...] Read more.
A set of ex-ZnAl-LDHs catalysts with a molar ratio of Zn/Al in the range of 0.3–1.0 was prepared using co-precipitation and thermal treatment. The samples were characterized using various methods, including X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy FT-IR, N2 adsorption, Temperature-programmed desorption of CO2 (TPD-CO2) as well as Scanning electron microscopy (SEM-EDS). Catalyst activity and long-term stability measurements were carried out in a high-temperature water–gas shift (HT-WGS) reaction. Mixed oxide catalysts with various Zn/Al molar ratios decorated with potassium showed high activity in the HT-WGS reaction within the temperature range of 330–400 °C. The highest activity was found for the Zn/Al molar ratio of 0.5 corresponding to spinel stoichiometry. However, the catalyst with a stoichiometric spinel molar ratio of Zn/Al (ZnAl_0.5_K) revealed a higher tendency for surface migration and/or vaporization of potassium during overheating at 450 °C. The correlation of the activity results and TPD-CO2 data show that medium basic sites enhance the progress of the HT-WGS reaction. Full article
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
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Open AccessFeature PaperArticle
Carbon Nanotube Formation on Cr-Doped Ferrite Catalyst during Water Gas Shift Membrane Reaction: Mechanistic Implications and Extended Studies on Dry Gas Conversions
Catalysts 2020, 10(8), 927; https://doi.org/10.3390/catal10080927 - 12 Aug 2020
Abstract
A nanocrystalline chromium-doped ferrite (FeCr) catalyst was shown to coproduce H2 and multiwalled carbon nanotubes (MWCNTs) during water gas shift (WGS) reaction in a H2-permselective zeolite membrane reactor (MR) at reaction pressures of ~20 bar. The FeCr catalyst was further [...] Read more.
A nanocrystalline chromium-doped ferrite (FeCr) catalyst was shown to coproduce H2 and multiwalled carbon nanotubes (MWCNTs) during water gas shift (WGS) reaction in a H2-permselective zeolite membrane reactor (MR) at reaction pressures of ~20 bar. The FeCr catalyst was further demonstrated in the synthesis of highly crystalline and dimensionally uniform MWCNTs from a dry gas mixture of CO and CH4, which were the apparent sources for MWCNT growth in the WGS MR. In both the WGS MR and dry gas reactions, the operating temperature was 500 °C, which is significantly lower than those commonly used in MWCNT production by chemical vapor deposition (CVD) method from CO, CH4, or any other precursor gases. Extensive ex situ characterizations of the reaction products revealed that the FeCr catalyst remained in partially reduced states of Fe3+/Fe2+ and Cr6+/Cr3+ in WGS membrane reaction while further reduction of Fe2+ to Fe0 occurred in the CO/CH4 dry gas environments. The formation of the metallic Fe nanoparticles or catalyst surface dramatically improved the crystallinity and dimensional uniformity of the MWCNTs from dry gas reaction as compared to that from WGS reaction in the MR. Reaction of the CO/CH4 mixture containing 500 ppmv H2S also resulted in high-quality MWCNTs similar to those from the H2S-free feed gas, demonstrating excellent sulfur tolerance of the FeCr catalyst that is practically meaningful for utilization of biogas and cheap coal-derived syngas. Full article
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
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Open AccessArticle
Elucidation of Water Promoter Effect of Proton Conductor in WGS Reaction over Pt-Based Catalyst: An Operando DRIFTS Study
Catalysts 2020, 10(8), 841; https://doi.org/10.3390/catal10080841 - 25 Jul 2020
Abstract
A conventional Pt/CeO2/Al2O3 catalyst physically mixed with an ionic conductor (Mo- or Eu-doped ZrO2) was tested at high space velocity (20,000 h−1 and 80 L h−1 gcat−1) under model conditions (only [...] Read more.
A conventional Pt/CeO2/Al2O3 catalyst physically mixed with an ionic conductor (Mo- or Eu-doped ZrO2) was tested at high space velocity (20,000 h−1 and 80 L h−1 gcat−1) under model conditions (only with CO and H2O) and industrial conditions, with a realistic feed. The promoted system with the ionic conductor physically mixed showed better catalytic activity associated with better water dissociation and mobility, considered as a rate-determining step. The water activation was assessed by operando diffuse reflectance infrared fourier transformed spectroscopy (DRIFTS) studies under reaction conditions and the Mo-containing ionic conductor exhibited the presence of both dissociated (3724 cm−1) and physisorbed (5239 cm−1) water on the Eu-doped ZrO2 solid solution, which supports the appearance of proton conductivity by Grotthuss mechanism. Moreover, the band at 3633 cm−1 ascribed to hydrated Mo oxide, which increases with the temperature, explains the increase of catalytic activity when the physical mixture was used in a water gas shift (WGS) reaction. Full article
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
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Open AccessArticle
Bimetallic Pt-Co Catalysts for the Liquid-Phase WGS
Catalysts 2020, 10(8), 830; https://doi.org/10.3390/catal10080830 - 24 Jul 2020
Abstract
Bimetallic Pt-Co catalysts derived from cobalt aluminate spinel were investigated in the liquid-phase water–gas shift (WGS) reaction and CO hydrogenation. Liquid-phase WGS is a key reaction in the aqueous-phase reforming (APR) of polyols; thus, WGS activity is essential to formulate good APR catalysts. [...] Read more.
Bimetallic Pt-Co catalysts derived from cobalt aluminate spinel were investigated in the liquid-phase water–gas shift (WGS) reaction and CO hydrogenation. Liquid-phase WGS is a key reaction in the aqueous-phase reforming (APR) of polyols; thus, WGS activity is essential to formulate good APR catalysts. In this work, catalysts with different Pt/Co molar ratios were synthesized together with a reference Pt/alumina. All the synthesized catalysts were characterized by various techniques in order to gain knowledge on their structural and surface characteristics. WGS activity was tested with a feedstream of CO/H2O = 1/15 (space-time of 76.8 kgcat·s/molCO), isothermal operation at 260 °C and 50 bar, for 10 TOS. Bimetallic Pt-Co catalysts showed improved activity in liquid-phase WGS in comparison to bare Co or Pt catalysts, which was ascribed to the synergistic effect. Despite being subjected to an increased hydrogen concentration in the feedstream (H2/CO between 0 and 12/3), these catalysts maintained a preferential selectivity towards WGS activity. In addition, the effect of temperature (220–260 °C) and pressure (25–50 bar) was investigated over a catalyst with 0.3Pt/CoAl. CO conversion and CO2 yield were more sensitive to temperature, while a higher pressure favored methane production. The measured activation energy in the 220–260 °C temperature range was 51.5 kJ/mol. Full article
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
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Open AccessFeature PaperArticle
FeCeOx Supported Ni, Sn Catalysts for the High-Temperature Water–Gas Shift Reaction
Catalysts 2020, 10(6), 639; https://doi.org/10.3390/catal10060639 - 08 Jun 2020
Cited by 2
Abstract
In this work, the effect of monometallic Ni or Sn and bimetallic NiSn deposition on the activity of FeCeOx catalysts in high-temperature water–gas (HT-WGS) reactions was investigated. It was found that the HT-WGS performance of FeCeOx has significantly improved after the [...] Read more.
In this work, the effect of monometallic Ni or Sn and bimetallic NiSn deposition on the activity of FeCeOx catalysts in high-temperature water–gas (HT-WGS) reactions was investigated. It was found that the HT-WGS performance of FeCeOx has significantly improved after the deposition of Sn together with Ni on it. Furthermore, the bimetallic NiSn/FeCeOx catalyst showed higher activity compared to the monometallic Ni/FeCeOx and Sn/FeCeOx catalysts within the tested temperature range (450–600 °C). Although the Ni/FeCeOx catalyst showed methanation activity at a temperature below 550 °C, the NiSn/FeCeOx catalyst suppressed the methane formation to zero in the WGS. Besides, the NiSn/FeCeOx catalyst exhibited an excellent time-on-stream stability without methanation reaction, even at a steam-to-CO ratio as low as 0.8. The combination of Ni and Sn supported on FeCeOx led to a large lattice strain, the formation of NiSn alloy, and a strong synergistic effect between the bimetallic NiSn and FeCeOx mixed oxide support interface. All these features are very important in achieving the best activity and stability of NiSn/FeCeOx in the HT-WGS reaction. Full article
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
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Open AccessArticle
Cr-Free, Cu Promoted Fe Oxide-Based Catalysts for High-Temperature Water-Gas Shift (HT-WGS) Reaction
Catalysts 2020, 10(3), 305; https://doi.org/10.3390/catal10030305 - 06 Mar 2020
Cited by 1
Abstract
Ca, Ni, Co, and Ge promoters were examined as potential candidates to substitute for the current toxic Cr in Cu-promoted Fe oxide-based catalysts for the HT-WGS reaction. The Ca and Ni promoters were found to improve catalyst performance relative to promotion with Cr. [...] Read more.
Ca, Ni, Co, and Ge promoters were examined as potential candidates to substitute for the current toxic Cr in Cu-promoted Fe oxide-based catalysts for the HT-WGS reaction. The Ca and Ni promoters were found to improve catalyst performance relative to promotion with Cr. The HS-LEIS surface analysis data demonstrate that Ca and Ge tend to segregate on the surface, while Ni, Co, and Cr form solid solutions in the Fe3O4 bulk lattice. The corresponding number of catalytic active sites, redox, and WGS activity values of the catalysts were determined with CO-TPR, CO+H2O-TPSR, and SS-WGS studies, respectively. The poorer HT-WGS performances of the Ge and Co promoters are related to the presence of surface Ge and Co that inhibits catalyst redox ability, with the Co also not stabilizing the surface area of the Fe3O4 support. The Ni promoter uniformly disperses the Cu nanoparticles on the catalyst surface and increases the number of FeOx-Cu interfacial redox sites. The Ca promoter on the catalyst surface, however, enhances the activity of the FeOx-Cu interfacial redox sites. The CO+H2O TPSR results reveal that the redox ability of the active sites follows the SS-WGS performance of the catalysts and show the following trend: 3Cu8CaFe > 3Cu8NiFe ≥ 3Cu8CrFe > 3Cu8CoFe >> 3Cu8GeFe. Furthermore, all the catalysts followed a redox-type reaction mechanism for the HT-WGS reaction. Full article
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
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Open AccessArticle
Promotional Effect of Gold on the WGS Activity of Alumina-Supported Copper-Manganese Mixed Oxides
Catalysts 2018, 8(11), 563; https://doi.org/10.3390/catal8110563 - 20 Nov 2018
Cited by 6
Abstract
The water-gas shift (WGS) reaction is a well-known industrial process used for the production of hydrogen. During the last few decades, it has attracted renewed attention due to the need for high-purity hydrogen for fuel-cell processing systems. The aim of the present study [...] Read more.
The water-gas shift (WGS) reaction is a well-known industrial process used for the production of hydrogen. During the last few decades, it has attracted renewed attention due to the need for high-purity hydrogen for fuel-cell processing systems. The aim of the present study was to develop a cost-effective and catalytically efficient formulation that combined the advantageous properties of transition metal oxides and gold nanoparticles. Alumina-supported copper- manganese mixed oxides were prepared by wet impregnation. The deposition-precipitation method was used for the synthesis of gold catalysts. The effect of the Cu:Mn molar ratio and the role of Au addition on the WGS reaction’s performance was evaluated. Considerable emphasis was put on the characterization of the as-prepared and WGS-tested samples by means of a number of physicochemical methods (X-ray powder diffraction, high-resolution transmission electron microscopy, electron paramagnetic resonance, X-ray photoelectron spectroscopy, and temperature-programmed reduction) in order to explain the relationship between the structure and the reductive and WGS behavior. Catalytic tests revealed the promotional effect of gold addition. The best performance of the gold-promoted sample with a higher Cu content, i.e., a Cu:Mn molar ratio of 2:1 might be related to the beneficial role of Au on the spinel decomposition and the highly dispersed copper particle formation during the reaction, thus, ensuring the presence of two highly dispersed active metallic phases. High-surface-area alumina that was modified with a surface fraction of Cu–Mn mixed oxides favored the stabilization of finely dispersed gold particles. These new catalytic systems are very promising for practical applications due to their economic viability because the composition mainly includes alumina (80%). Full article
(This article belongs to the Special Issue Catalysts for Water-Gas Shift Reaction)
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