Special Issue "Emissions Control Catalysis"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: 31 December 2018

Special Issue Editors

Guest Editor
Prof. Dr. Ioannis (Yannis) V. Yentekakis

School of Environmental Engineering, Technical University of Crete (Polytechnion Kritis), 73100 Chania, Crete, Greece
Website 1 | Website 2 | E-Mail
Phone: +30-28210-37752
Interests: nano-structured materials and heterogeneous catalysis; thin film electrocatalysts and fuel cells, electrodes and solid electrolytes, materials characterization; materials for energy; materials for environmental protection
Guest Editor
Dr. Philippe Vernoux

CNRS - IRCELYON, France
Website | E-Mail
Interests: ionically conducting ceramics as active catalyst supports; catalysis for car exhaust treatment; solid oxide fuel cells; potentiometric sensors

Special Issue Information

Dear Colleagues,

Important advances have been achieved over the past few years in agriculture, industrial technology, energy, and health, which have contributed to human well-being. However, some of these improvements in our lives have resulted in changes to the environment around us, with photochemical smog, stratospheric ozone depletion, acid rain, global warming and finally climate change being the most well-known major issues, as a result of a variety of pollutants emitted through these human activities.

Aiming to ensure that “we live well, within the planet’s ecological limits”, scientists around the world are developing tools and techniques that enable us to effectively control emissions, either of mobile (e.g., cars) or stationary (industry) sources, and to improve the quality of outdoor and indoor air, with catalysis to play a major role on these efforts.  “Emissions Control Catalysis” in the frame of Environmental Catalysis is continuously growing up, providing novel multifunctional, nano-structured materials, promoted by several ways (i.e., surface or support induced promotion, electrochemical promotion, alloys, etc.) in order to be very active and selective for the abatement of a variety of pollutants and greenhouse gases, such as CO, NOx, N2O, NH3, CH4, higher hydrocarbons, Volatile Organic Compounds (VOCs) and particle matter (PM) as well as other specific pollutants emitted by industry (e.g., SOx, H2S, dioxins, aromatic hydrocarbons) or landfill and wastewater treatment plants (biogas). In many cases the concept of Cyclic Economy is concerned in emission control catalysis strategies for the production of useful chemicals and fuels from the controlled pollutants (e.g., CO2 hydrogenation, syngas production from biogas, etc.).

The present Special Issue aims to cover recent research progress in the field of the catalytic control of air pollutants emitted by mobile or stationary sources, not limited only to the abatement but also including possible cyclic economy strategies, and ranging from the synthesis, physicochemical-textural-structural characterization of the materials, activity-selectivity- durability evaluation under the considered reactions, fundamental understanding of structure-activity relationships or other metal-metal and metal-support interactions on the multifunctional materials involved, as well as simulation studies of materials, catalytic reactions and processes.

Prof. Dr. Ioannis V. Yentekakis
Dr. Philippe Vernoux
Guest Editors

Manuscript Submission Information

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Keywords

  • Environmental catalysis
  • NOx, N2O, NH3, CO, SOx, H2S, CH4, VOCs, aromatics, dioxins, PM pollutants abatement
  • Greenhouse gases control
  • Cyclic Economy
  • Heterogeneous catalysis
  • Structure-activity correlation
  • Metal-support interactions
  • Nano-structured multifunctional materials
  • Automotive pollution control
  • Catalyst promotion
  • Electrochemical promotion

Published Papers (6 papers)

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Research

Open AccessArticle Low-Temperature Electrocatalytic Conversion of CO2 to Liquid Fuels: Effect of the Cu Particle Size
Catalysts 2018, 8(8), 340; https://doi.org/10.3390/catal8080340
Received: 30 July 2018 / Revised: 9 August 2018 / Accepted: 14 August 2018 / Published: 20 August 2018
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Abstract
A novel gas-phase electrocatalytic system based on a low-temperature proton exchange membrane (Sterion) was developed for the gas-phase electrocatalytic conversion of CO2 to liquid fuels. This system achieved gas-phase electrocatalytic reduction of CO2 at low temperatures (below 90 °C) over a
[...] Read more.
A novel gas-phase electrocatalytic system based on a low-temperature proton exchange membrane (Sterion) was developed for the gas-phase electrocatalytic conversion of CO2 to liquid fuels. This system achieved gas-phase electrocatalytic reduction of CO2 at low temperatures (below 90 °C) over a Cu cathode by using water electrolysis-derived protons generated in-situ on an IrO2 anode. Three Cu-based cathodes with varying metal particle sizes were prepared by supporting this metal on an activated carbon at three loadings (50, 20, and 10 wt %; 50% Cu-AC, 20% Cu-AC, and 10% Cu-AC, respectively). The cathodes were characterized by N2 adsorption–desorption, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) and their performance towards the electrocatalytic conversion of CO2 was subsequently studied. The membrane electrode assembly (MEA) containing the cathode with the largest Cu particle size (50% Cu-AC, 40 nm) showed the highest CO2 electrocatalytic activity per mole of Cu, with methyl formate being the main product. This higher electrocatalytic activity was attributed to the lower Cu–CO bonding strength over large Cu particles. Different product distributions were obtained over 20% Cu-AC and 10% Cu-AC, with acetaldehyde and methanol being the main reaction products, respectively. The CO2 consumption rate increased with the applied current and reaction temperature. Full article
(This article belongs to the Special Issue Emissions Control Catalysis)
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Open AccessArticle Promotional Effect of Cerium and/or Zirconium Doping on Cu/ZSM-5 Catalysts for Selective Catalytic Reduction of NO by NH3
Catalysts 2018, 8(8), 306; https://doi.org/10.3390/catal8080306
Received: 7 July 2018 / Revised: 22 July 2018 / Accepted: 24 July 2018 / Published: 28 July 2018
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Abstract
The cerium and/or zirconium-doped Cu/ZSM-5 catalysts (CuCexZr1−xOy/ZSM-5) were prepared by ion exchange and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction by hydrogen (H2-TPR). Activities of the
[...] Read more.
The cerium and/or zirconium-doped Cu/ZSM-5 catalysts (CuCexZr1−xOy/ZSM-5) were prepared by ion exchange and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction by hydrogen (H2-TPR). Activities of the catalysts obtained on the selective catalytic reduction (SCR) of nitric oxide (NO) by ammonia were measured using temperature programmed reactions. Among all the catalysts tested, the CuCe0.75Zr0.25Oy/ZSM-5 catalyst presented the highest catalytic activity for the removal of NO, corresponding to the broadest active window of 175–468 °C. The cerium and zirconium addition enhanced the activity of catalysts, and the cerium-rich catalysts exhibited more excellent SCR activities as compared to the zirconium-rich catalysts. XRD and TEM results indicated that zirconium additions improved the copper dispersion and prevented copper crystallization. According to XPS and H2-TPR analysis, copper species were enriched on the ZSM-5 grain surfaces, and part of the copper ions were incorporated into the zirconium and/or cerium lattice. The strong interaction between copper species and cerium/zirconium improved the redox abilities of catalysts. Furthermore, the introduction of zirconium abates N2O formation in the tested temperature range. Full article
(This article belongs to the Special Issue Emissions Control Catalysis)
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Open AccessArticle Hydrogen Production from Chemical Looping Reforming of Ethanol Using Ni/CeO2 Nanorod Oxygen Carrier
Catalysts 2018, 8(7), 257; https://doi.org/10.3390/catal8070257
Received: 8 June 2018 / Revised: 22 June 2018 / Accepted: 22 June 2018 / Published: 25 June 2018
Cited by 1 | PDF Full-text (3598 KB) | HTML Full-text | XML Full-text
Abstract
Chemical looping reforming (CLR) technique is a prospective option for hydrogen production. Improving oxygen mobility and sintering resistance are still the main challenges of the development of high-performance oxygen carriers (OCs) in the CLR process. This paper explores the performance of Ni/CeO2
[...] Read more.
Chemical looping reforming (CLR) technique is a prospective option for hydrogen production. Improving oxygen mobility and sintering resistance are still the main challenges of the development of high-performance oxygen carriers (OCs) in the CLR process. This paper explores the performance of Ni/CeO2 nanorod (NR) as an OC in CLR of ethanol. Various characterization methods such as N2 adsorption-desorption, X-ray diffraction (XRD), Raman spectra, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (TPR), and H2 chemisorption were utilized to study the properties of fresh OCs. The characterization results show the Ni/CeO2-NR possesses high Ni dispersion, abundant oxygen vacancies, and strong metal-support interaction. The performance of prepared OCs was tested in a packed-bed reactor. H2 selectivity of 80% was achieved by Ni/CeO2-NR in 10-cycle stability test. The small particle size and abundant oxygen vacancies contributed to the water gas shift reaction, improving the catalytic activity. The covered interfacial Ni atoms closely anchored on the underlying surface oxygen vacancies on the (111) facets of CeO2-NR, enhancing the anti-sintering capability. Moreover, the strong oxygen mobility of CeO2-NR also effectively eliminated surface coke on the Ni particle surface. Full article
(This article belongs to the Special Issue Emissions Control Catalysis)
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Open AccessArticle Synthesis of Sulfur-Resistant TiO2-CeO2 Composite and Its Catalytic Performance in the Oxidation of a Soluble Organic Fraction from Diesel Exhaust
Catalysts 2018, 8(6), 246; https://doi.org/10.3390/catal8060246
Received: 13 May 2018 / Revised: 8 June 2018 / Accepted: 11 June 2018 / Published: 14 June 2018
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Abstract
Sulfur poisoning is one of the most important factors deteriorating the purification efficiency of diesel exhaust after-treatment system, thus improving the sulfur resistibility of catalysts is imperative. Herein, ceria oxygen storage material was introduced into a sulfur-resistant titania by a co-precipitation method, and
[...] Read more.
Sulfur poisoning is one of the most important factors deteriorating the purification efficiency of diesel exhaust after-treatment system, thus improving the sulfur resistibility of catalysts is imperative. Herein, ceria oxygen storage material was introduced into a sulfur-resistant titania by a co-precipitation method, and the sulfur resistibility and catalytic activity of prepared TiO2-CeO2 composite in the oxidation of diesel soluble organic fraction (SOF) were studied. Catalytic performance testing results show that the CeO2 modification significantly improves the catalytic SOF purification efficiency of TiO2-CeO2 catalyst. SO2 uptake and energy-dispersive X-ray (EDX) results suggest that the ceria doping does not debase the excellent sulfur resistibility of bare TiO2, the prepared TiO2-CeO2 catalyst exhibits obviously better sulfur resistibility than the CeO2 and commercial CeO2-ZrO2-Al2O3. X-ray powder diffraction (XRD) and Raman spectra indicate that cerium ions can enter into the TiO2 lattice and not form complete CeO2 crystals. X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR) and oxygen storage capacity (OSC) testing results imply that the addition of CeO2 in TiO2-CeO2 catalyst can significantly enhance the surface oxygen concentration and oxygen storage capacity of TiO2-CeO2. Full article
(This article belongs to the Special Issue Emissions Control Catalysis)
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Open AccessArticle CuO Nanoparticles Supported on TiO2 with High Efficiency for CO2 Electrochemical Reduction to Ethanol
Catalysts 2018, 8(4), 171; https://doi.org/10.3390/catal8040171
Received: 7 March 2018 / Revised: 7 April 2018 / Accepted: 18 April 2018 / Published: 21 April 2018
Cited by 1 | PDF Full-text (5756 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Non-noble metal oxides consisting of CuO and TiO2 (CuO/TiO2 catalyst) for CO2 reduction were fabricated using a simple hydrothermal method. The designed catalysts of CuO could be in situ reduced to a metallic Cu-forming Cu/TiO2 catalyst, which could efficiently
[...] Read more.
Non-noble metal oxides consisting of CuO and TiO2 (CuO/TiO2 catalyst) for CO2 reduction were fabricated using a simple hydrothermal method. The designed catalysts of CuO could be in situ reduced to a metallic Cu-forming Cu/TiO2 catalyst, which could efficiently catalyze CO2 reduction to multi-carbon oxygenates (ethanol, acetone, and n-propanol) with a maximum overall faradaic efficiency of 47.4% at a potential of −0.85 V vs. reversible hydrogen electrode (RHE) in 0.5 M KHCO3 solution. The catalytic activity for CO2 electroreduction strongly depends on the CuO contents of the catalysts as-prepared, resulting in different electrochemistry surface areas. The significantly improved CO2 catalytic activity of CuO/TiO2 might be due to the strong CO2 adsorption ability. Full article
(This article belongs to the Special Issue Emissions Control Catalysis)
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Open AccessFeature PaperArticle Gas-Phase Phosphorous Poisoning of a Pt/Ba/Al2O3 NOx Storage Catalyst
Catalysts 2018, 8(4), 155; https://doi.org/10.3390/catal8040155
Received: 9 March 2018 / Revised: 5 April 2018 / Accepted: 7 April 2018 / Published: 11 April 2018
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Abstract
The effect of phosphorous exposure on the NOx storage capacity of a Pt/Ba/Al2O3 catalyst coated on a ceramic monolith substrate has been studied. The catalyst was exposed to phosphorous by evaporating phosphoric acid in presence of H2O
[...] Read more.
The effect of phosphorous exposure on the NOx storage capacity of a Pt/Ba/Al2O3 catalyst coated on a ceramic monolith substrate has been studied. The catalyst was exposed to phosphorous by evaporating phosphoric acid in presence of H2O and O2. The NOx storage capacity was measured before and after the phosphorus exposure and a significant loss of the NOx storage capacity was detected after phosphorous exposure. The phosphorous poisoned samples were characterized by X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), N2-physisorption and inductive coupled plasma atomic emission spectroscopy (ICP-AES). All characterization methods showed an axial distribution of phosphorous ranging from the inlet to the outlet of the coated monolith samples with a higher concentration at the inlet of the samples. Elemental analysis, using ICP-AES, confirmed this distribution of phosphorous on the catalyst surface. The specific surface area and pore volume were significantly lower at the inlet section of the monolith where the phosphorous concentration was higher, and higher at the outlet where the phosphorous concentration was lower. The results from the XPS and scanning electron microscopy (SEM)-energy dispersive X-ray (EDX) analyses showed higher accumulation of phosphorus towards the surface of the catalyst at the inlet of the monolith and the phosphorus was to a large extent present in the form of P4O10. However, in the middle section of the monolith, the XPS analysis revealed the presence of more metaphosphate (PO3). Moreover, the SEM-EDX analysis showed that the phosphorous to higher extent had diffused into the washcoat and was less accumulated at the surface close to the outlet of the sample. Full article
(This article belongs to the Special Issue Emissions Control Catalysis)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Investigation of Co3O4-Cu2O-CeO2 mixed oxides as diesel soot oxidation catalysts
Authors: L.F. Liotta 1,*, A. Westermann 2, A. Serve 2, F. Puleo 1, V. La Parola 1, A. Giroir-Fendler 2, P. Vernoux 2,*
Affiliation:
1Istituto per Lo Studio dei Materiali Nanostrutturati (ISMN)-CNR via Ugo La Malfa, 153, 90146, Palermo, Italy.
2Université de Lyon, CNRS, Université Claude Bernard Lyon 1, IRCELYON, UMR 5256, 2 avenue A. Einstein, 69626 Villeurbanne, France
*leonarda.liotta@ismn.cnr.it; *philippe.vernoux@ircelyon.univ-lyon1.fr
Abstract: In the present work, Co3O4-Cu0.05Ce0.95O2-d mixed oxides with cobalt loading equal to 2.5, 5, 7.5 and 10 wt% were prepared by one-pot citrate sol-gel method and calcined at 550 °C for 5 h. For comparison, Co-free Cu0.05Ce0.95O2-d and undoped CeO2 oxides were also synthesized. Characterizations by XRD, BET, TPR, XPS, Raman, Environmental TEM (ETEM) and SEM techniques were performed.
Peaks ascribed to CeO2 fluorite phase were detected in all the XRD patterns along with features of Co3O4 spinel, visible for Co loading ³ 5wt%. The crystallization of cobalt as Co3O4 was confirmed by Raman spectroscopy, while copper was present as Cu+ , according with Raman and XPS spectra, likely forming CuxOy and/or CoxCu1-xOy amorphous phases. No angular shift in the position of CeO2 peaks occurred as results by comparing XRD patterns of Co3O4-Cu0.05Ce0.95O2-d with Co-free Cu0.05Ce0.95O2-d and undoped CeO2, confirming no insertion of Co neither of Cu ions into the ceria lattice. The main effect was a visible broadening of the ceria peaks for the Cu0.05Ce0.95O2-d and for all the mixed oxides Co3O4/Cu0.05Ce0.95O2 that were characterized by smaller crystallites and higher specific surface area than parent Co3O4 and CeO2 oxides.
Soot oxidation tests were carried out under tight contact by flowing O2 (5% in He) over 25 mg of a mixture of catalyst and soot (Printex U), at mass ratio 4:1. The best oxidation performances were achieved for 5%wt of Co that was characterized by Co3O4 homogeneously distributed in the matrix and partially encapsulated into Cu2O-CeO2, as suggested by Raman and ETEM analyses.

Title: Catalytic properties of double substituted lanthanum cobaltite nanowires elaborated by reactive magnetron sputtering
Authors: Philippe Vernoux and Pascal Briois
Abstract: Lanthanum cobaltite coatings (LaCoO3) are synthesized by reactive magnetron sputtering with La and Co metallic targets in Ar/O2 reactive atmosphere. Films’s composition depends on the intensity dissipated on every target and on the injected oxygen flow. As-deposited, coatings presenting the aimed composition are amorphous. They crystallize under the cubic structure of the LaCoO3 after an annealing treatment at 773 K during 2 hours under air. Nevertheless, a lot of cracks are formed due to the mismatch of thermal expansion coefficient between the film and the substrate. To avoid this phenomenon, the study focuses on the synthesis of lanthanum cobaltite double substituted by Ag and by Sr on the La site of the perovskite. The chemical formula of this material is La1-x-ySrxAgyCoO3-α ; Film’s morphology is strongly influenced by the Ag content. Indeed, when the Ag content varies from 14 to 48 %, the film’s morphology evolves from a dense aspect to a nanostructured aspect (nanowires) of perovskite oxide. All compounds present a good mechanical behavior during annealing treatment of 2 hours at 773 K under air.
The obtaining of such a morphology increases the specific surface area of films and leads to the very promizing results obtained during catalytic tests. Indeed, performances close to those of Pt, which is the reference material for the catalysis, are reached.

Title: Electropositive promotion by alkalis or alkaline earths of Pt-group metals in emission control catalysis: A Status Report.
Authors: Ioannis V. Yentekakis1,*, Philippe Vernoux2, Grammatiki Goula1, Angel Caravaca2
Affiliation: 1 Laboratory of Physical Chemistry & Chemical Processes (www.pccplab.tuc.gr ), School of Environmental Engineering, Technical University of Crete (TUC), 73100 Chania, Crete, Greece.
2 Institut de Recherches sur la Catalyse et l'Environnement de Lyon, LyonTech-La Doua campus, IRCELYON, 2 avenue Albert Einstein, F-69626, Villeurbanne Cedex, France.
*Corresponding Author, E-mail: yyentek@isc.tuc.gr
Abstract: Recent studies have shown that the catalytic performance (activity and/or selectivity) of Pt-group metal (PGM) catalysts for the CO and hydrocarbons oxidation as well as for the (CO, HCs or H2)-SCR of NOx or N2O can be remarkably affected through surface-induced promotion by successful application of electropositive promoters, alkalis or alkaline earths, imposed either electrochemically (EPOC concept) or via conventional ways (conventional surface promotion concept). Turnover rate enhancements by up to two orders of magnitude were typically achievable for the reduction of NOx by hydrocarbons or CO, in the presence or absence of oxygen. Subsequent improvements, typically 30-60 additional percentage units, in selectivity towards N2 were also observed. Electropositively promoted PGMs have also been found to be significantly more active for CO and hydrocarbons oxidation, and these reactions either occur simultaneously with De-NOx reactions or not. The aforementioned promotion was also found to act synergistically with the typically applied in TWCs washcoats structural promotion by Ce-La-Zr solid solutions. These attractive findings prompt to the development of novel catalyst formulations for a more efficient and economic emissions’ control of automotive and stationary sources. In this report the literature data in the relevant area is summarized, classified and discussed. The mechanism and the mode of action of the electropositive promoters are consistently interpreted with all the observed promoting phenomena, in terms of indirect (kinetics) and direct (spectroscopic) evidences.
Keywords: Platinum; Palladium; Rhodium; Iridium; NO; N2O; Propene; CO; Methane; Alkali; Alkaline earth; Platinum group metals; de-NOx chemistry; Lean burn conditions; TWC

Title: Electrochemical Promotion of Nanostructured Palladium for Complete Methane Oxidation
Authors: Yasmine M. Hajar, Balaji Venkatesh, Elena A. Baranova*
Affiliation: Department of Chemical and Biological Engineering, Centre for Catalysis Research and Innovation (CCRI), University of Ottawa, 161 Louis-Pasteur, Ottawa, ON K1N 6N5, Canada
*Corresponding author: tel: 16135625800 (x 6302); fax: 16135625172;
Email: elena.baranova@uottawa.ca (Elena A. Baranova)
Abstract: Complete methane oxidation reaction was investigated on Pd nanoparticles (NPs) deposited on yttria-stabilized zirconia (8mol% Y2O3-ZrO2) under open circuit and electrochemical promotion of catalysis (EPOC) conditions. Pd NPs were synthesized using polyol synthesis method using ethylene glycol as a reducing and stabilizing agent. Methane oxidation was carried out under galvanic and potentiostatic conditions at different temperatures (350-450 oC) and reactants ratios. It was found that positive (anodic) polarization of Pd NPs leads to a reaction rate increase, while negative polarization did not have any effect on the methane oxidation reaction rate. Under positive polarization the supply of Oδ- promoters to Pd NPs active surface and consecutive formation of the effective double layer resulted in the weakening of oxygen adsorption strength and significant reaction rate increase. Under galvanostatic conditions, a value as low as 1 mA was able to increase the catalytic rate in a non-Faradaic way with a Faradaic efficiency above 3000 and an enhancement ratio of 120%. This work demonstrates a feasibility of EPOC with highly dispersed, low loading Pd NPs for complete methane oxidation.

Title: A Review of Low Temperature SCR for Removal of NOx
Authors: Devaiah Damma and Panagiotis G. Smirniotis
Affiliation: Chemical Engineering, College of Engineering & Applied Science, University of Cincinnati, Cincinnati, OH 45221-0012, USA
Abstract: The importance of the low-temperature selective catalytic reduction (LT-SCR) of NOx by NH3 is increasing due to the recent severe air pollution regulations being imposed around the world. Supported transition metal oxides have been widely investigated for the LT-SCR technology. However, these catalytic materials have some drawbacks, especially in terms of catalyst poisoning by H2O or/and SO2, and insufficient activity. The development of catalysts for the LT-SCR process is still under active investigation throughout for the sake of better performance. Extensive research efforts have been made to develop new advanced materials for this technology. This article critically reviews the recent research progress on supported transition and mixed transition metal oxide catalysts for the LT-SCR reaction. The reaction mechanism, reaction intermediates, and active sites are discussed in detail using isotopic labeled and in situ FT-IR studies. The review also covered the description of the influence of operating conditions and promoters on the LT-SCR performance.

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