Special Issue "Catalysis by Metals on Perovskite-Type Oxides"

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

Deadline for manuscript submissions: closed (28 February 2019).

Special Issue Editor

Dr. Davide Ferri
E-Mail Website
Guest Editor
Catalysis for Energy, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
Interests: heterogeneous catalysis; environmental catalysis; operando spectroscopy; IR spectroscopy; perovskite-type oxides; functional materials
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Perovskite-type oxides are widely explored in a number of environment and energy related research fields. This Special Issue on “Catalysis by Metals on Perovskite-Type Oxides” will provide updates on the recent advances in the catalytic applications of transition metals dispersed on perovskite-type oxides and their working structure. Topics related to catalyst activation, metal segregation, metal atoms protection by oxidation, poisoning, degradation and effect of redox treatments will be of interest. Contributions to this Special Issue are expected to include structural analysis of the active metal phase and of the perovskite-type support using spectroscopy, diffraction and microscopy methods. Determination of structure during reaction would be just ideal. Submissions to this Special Issue are welcome in the form of original research papers or short reviews reflecting the knowledge in the field of perovskite-type mixed oxides within the following thematic subjects: Heterogeneous catalysis; automotive catalysis; electrocatalysis; and structure by operando methods.

Dr. Davide Ferri
Guest Editor

Manuscript Submission Information

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Keywords

  • perovskite-type mixed oxides
  • d-metals
  • catalysis
  • spectroscopy
  • material structure
  • environment
  • energy
  • operando methods

Published Papers (9 papers)

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Research

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Open AccessArticle
Reactive Grinding Synthesis of LaBO3 (B: Mn, Fe) Perovskite; Properties for Toluene Total Oxidation
Catalysts 2019, 9(8), 633; https://doi.org/10.3390/catal9080633 - 25 Jul 2019
Abstract
LaBO3 (B: Mn, Fe) perovskites were synthesized using a three-step reactive grinding process followed by a calcination at 400 °C for 3 h. The three successive steps are: (i) solid state synthesis (SSR); (ii) high-energy ball milling (HEBM); (iii) low-energy ball milling [...] Read more.
LaBO3 (B: Mn, Fe) perovskites were synthesized using a three-step reactive grinding process followed by a calcination at 400 °C for 3 h. The three successive steps are: (i) solid state synthesis (SSR); (ii) high-energy ball milling (HEBM); (iii) low-energy ball milling (LEBM) in wet conditions. The impact of each step of the synthesis on the material characteristics was deeply investigated using physico-chemical techniques (X-ray diffraction (XRD), N2-physisorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS)) and the catalytic performances of the synthesized materials were evaluated for the toluene total oxidation reaction. Starting from single oxides, microcrystalline perovskite phase, exhibiting negligible surface areas, is obtained after the SSR step. The HEBM step leads to a drastic reduction of the mean crystal size down to ~20 nm, along with formation of dense aggregates. Due to this strong aggregation, surface area remains low, typically below 4 m2·g−1. In contrast, the second grinding step, namely LEBM, allows particle deagglomeration resulting in increasing the surface area up to 18.8 m2·g−1 for LaFeO3. Regardless of the perovskite composition, the performance toward toluene oxidation reaction increases at each step of the process: SSR < HEBM < LEBM. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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Open AccessArticle
Catalytic Oxidation of NO over LaCo1−xBxO3 (B = Mn, Ni) Perovskites for Nitric Acid Production
Catalysts 2019, 9(5), 429; https://doi.org/10.3390/catal9050429 - 08 May 2019
Abstract
Nitric acid (HNO3) is an important building block in the chemical industry. Industrial production takes place via the Ostwald process, where oxidation of NO to NO2 is one of the three chemical steps. The reaction is carried out as a [...] Read more.
Nitric acid (HNO3) is an important building block in the chemical industry. Industrial production takes place via the Ostwald process, where oxidation of NO to NO2 is one of the three chemical steps. The reaction is carried out as a homogeneous gas phase reaction. Introducing a catalyst for this reaction can lead to significant process intensification. A series of LaCo1−xMnxO3 (x = 0, 0.25, 0.5 and 1) and LaCo1−yNiyO3 (y = 0, 0.25, 0.50, 0.75 and 1) were synthesized by a sol-gel method and characterized using N2 adsorption, ex situ XRD, in situ XRD, SEM and TPR. All samples had low surface areas; between 8 and 12 m2/g. The formation of perovskites was confirmed by XRD. The crystallite size decreased linearly with the degree of substitution of Mn/Ni for partially doped samples. NO oxidation activity was tested using a feed (10% NO and 6% O2) that partly simulated nitric acid plant conditions. Amongst the undoped perovskites, LaCoO3 had the highest activity; with a conversion level of 24.9% at 350 °C; followed by LaNiO3 and LaMnO3. Substitution of LaCoO3 with 25% mol % Ni or Mn was found to be the optimum degree of substitution leading to an enhanced NO oxidation activity. The results showed that perovskites are promising catalysts for NO oxidation at industrial conditions. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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Open AccessArticle
BaTi0.8B0.2O3 (B = Mn, Fe, Co, Cu) LNT Catalysts: Effect of Partial Ti Substitution on NOx Storage Capacity
Catalysts 2019, 9(4), 365; https://doi.org/10.3390/catal9040365 - 18 Apr 2019
Abstract
The effect of partial Ti substitution by Mn, Fe, Co, or Cu on the NOx storage capacity (NSC) of a BaTi0.8B0.2O3 lean NOx trap (LNT) catalyst has been analyzed. The BaTi0.8B0.2O3 catalysts were [...] Read more.
The effect of partial Ti substitution by Mn, Fe, Co, or Cu on the NOx storage capacity (NSC) of a BaTi0.8B0.2O3 lean NOx trap (LNT) catalyst has been analyzed. The BaTi0.8B0.2O3 catalysts were prepared using the Pechini’s sol–gel method for aqueous media. The characterization of the catalysts (BET, ICP-OES, XRD and XPS) reveals that: i) the partial substitution of Ti by Mn, Co, or Fe changes the perovskite structure from tetragonal to cubic, whilst Cu distorts the raw tetragonal structure and promotes the segregation of Ba2TiO4 (which is an active phase for NOx storage) as a minority phase and ii) the amount of oxygen vacancies increases after partial Ti substitution, with the BaTi0.8Cu0.2O3 catalyst featuring the largest amount. The BaTi0.8Cu0.2O3 catalyst shows the highest NSC at 400 °C, based on NOx storage cyclic tests, which is within the range of highly active noble metal-based catalysts. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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Open AccessArticle
Perovskite-type LaFeO3: Photoelectrochemical Properties and Photocatalytic Degradation of Organic Pollutants Under Visible Light Irradiation
Catalysts 2019, 9(4), 342; https://doi.org/10.3390/catal9040342 - 08 Apr 2019
Cited by 11
Abstract
Perovskite-type oxides lanthanum ferrite (LaFeO3) photocatalysts were successfully prepared by a facile and cost-effective sol-gel method using La(NO)3 and Fe(NO)3 as metal ion precursors and citric acid as a complexing agent at different calcination temperatures. The properties of the [...] Read more.
Perovskite-type oxides lanthanum ferrite (LaFeO3) photocatalysts were successfully prepared by a facile and cost-effective sol-gel method using La(NO)3 and Fe(NO)3 as metal ion precursors and citric acid as a complexing agent at different calcination temperatures. The properties of the resulting LaFeO3 samples were characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDXS), UV-Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (IR), transmission electron microscopy (TEM), N2 adsorption/desorption and photoelectrochemical tests. The photoactivity of the LaFeO3 samples was tested by monitoring the photocatalytic degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) under visible light irradiation, the highest photocatalytic activity was found for LaFeO3 calcined at 700 °C, which attributed to the relatively highest surface area (10.6 m2/g). In addition, it was found from trapping experiments that the reactive species for degradation were superoxide radical ions (O2) and holes (h+). Photocurrent measurements and electrochemical impedance spectroscopy (EIS) proved the higher photo-induced charge carrier transfer and separation efficiency of the LaFeO3 sample calcined at 700 °C compared to that that calcined at 900 °C. Band positions of LaFeO3 were estimated using the Mott-Schottky plots, which showed that H2 evolution was not likely. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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Open AccessArticle
Segregation of Nickel/Iron Bimetallic Particles from Lanthanum Doped Strontium Titanates to Improve Sulfur Stability of Solid Oxide Fuel Cell Anodes
Catalysts 2019, 9(4), 332; https://doi.org/10.3390/catal9040332 - 03 Apr 2019
Abstract
Perovskite derived Ni catalysts offer the remarkable benefit of regeneration after catalyst poisoning or Ni particle growth through the reversible segregation of Ni from the perovskite-type oxide host. Although this property allows for repeated catalyst regeneration, improving Ni catalyst stability towards sulfur poisoning [...] Read more.
Perovskite derived Ni catalysts offer the remarkable benefit of regeneration after catalyst poisoning or Ni particle growth through the reversible segregation of Ni from the perovskite-type oxide host. Although this property allows for repeated catalyst regeneration, improving Ni catalyst stability towards sulfur poisoning by H2S is highly critical in solid oxide fuel cells. In this work Mn, Mo, Cr and Fe were combined with Ni at the B-site of La0.3Sr0.55TiO3±δ to explore possible benefits of segregation of two transition metals towards sulfur tolerance. Catalytic activity tests towards the water gas shift reaction were carried out to evaluate the effect of the additional metal on the catalytic activity and sulfur stability of the Ni catalyst. The addition of Fe to the Ni perovskite catalyst was found to increase sulfur tolerance. The simultaneous segregation of Fe and Ni from La0.3Sr0.55Ti0.95-xNi0.05FexO3±δ (x ≤ 0.05) was investigated by temperature programmed reduction, X-ray diffraction and X-ray absorption spectroscopy and catalytic tests after multiple redox cycles. It is shown that catalytic properties of the active phase were affected likely by the segregation of Ni/Fe alloy particles and that the reversible segregation of Ni persisted, while it was limited in the case of Fe under the same conditions. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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Open AccessArticle
On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation
Catalysts 2019, 9(4), 312; https://doi.org/10.3390/catal9040312 - 30 Mar 2019
Abstract
The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping [...] Read more.
The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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Open AccessArticle
Fe-Doping in Double Perovskite PrBaCo2(1-x)Fe2xO6-δ: Insights into Structural and Electronic Effects to Enhance Oxygen Evolution Catalyst Stability
Catalysts 2019, 9(3), 263; https://doi.org/10.3390/catal9030263 - 14 Mar 2019
Cited by 2
Abstract
Perovskite oxides have been gaining attention for its capability to be designed as an ideal electrocatalyst for oxygen evolution reaction (OER). Among promising candidates, the layered double perovskite—PrBaCo2O6-δ (PBC)—has been identified as the most active perovskite electrocatalyst for OER in [...] Read more.
Perovskite oxides have been gaining attention for its capability to be designed as an ideal electrocatalyst for oxygen evolution reaction (OER). Among promising candidates, the layered double perovskite—PrBaCo2O6-δ (PBC)—has been identified as the most active perovskite electrocatalyst for OER in alkaline media. For a single transition metal oxide catalyst, the addition of Fe enhances its electrocatalytic performance towards OER. To understand the role of Fe, herein, Fe is incorporated in PBC in different ratios, which yielded PrBaCo2(1-x)Fe2xCo6-δ (x = 0, 0.2 and 0.5). Fe-doped PBCF’s demonstrate enhanced OER activities and stabilities. Operando X-ray absorption spectroscopy (XAS) revealed that Co is more stable in a lower oxidation state upon Fe incorporation by establishing charge stability. Hence, the degradation of Co is inhibited such that the perovskite structure is prolonged under the OER conditions, which allows it to serve as a platform for the oxy(hydroxide) layer formation. Overall, our findings underline synergetic effects of incorporating Fe into Co-based layered double perovskite in achieving a higher activity and stability during oxygen evolution reaction. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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Open AccessArticle
K-Modulated Co Nanoparticles Trapped in La-Ga-O as Superior Catalysts for Higher Alcohols Synthesis from Syngas
Catalysts 2019, 9(3), 218; https://doi.org/10.3390/catal9030218 - 27 Feb 2019
Cited by 1
Abstract
Owing to the outstanding catalytic performance for higher alcohol synthesis, Ga-Co catalysts have attracted much attention. In view of their unsatisfactory stability and alcohol selectivity, herein, K-modulated Co nanoparticles trapped in La-Ga-O catalysts were prepared by the reduction of La1−xKx [...] Read more.
Owing to the outstanding catalytic performance for higher alcohol synthesis, Ga-Co catalysts have attracted much attention. In view of their unsatisfactory stability and alcohol selectivity, herein, K-modulated Co nanoparticles trapped in La-Ga-O catalysts were prepared by the reduction of La1−xKxCo0.65Ga0.35O3 perovskite precursor. Benefiting from the atomic dispersion of all the elements in the precursor, during the reduction of La1−xKxCo0.65Ga0.35O3, Co nanoparticles could be confined into the K-modified La-Ga-O composite oxides, and the confinement of La-Ga-O could improve the anti-sintering performance of Co nanoparticles. In addition, the addition of K modulated parts of La-Ga-O into La2O3, which ameliorated the anti-carbon deposition performance. Finally, the addition of K increased the dispersion of cobalt and provided more electron donors to metallic Co, resulting in a high activity and superior selectivity to higher alcohols. Benefiting from the above characteristics, the catalyst possesses excellent activity, good selectivity, and superior stability. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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Review

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Open AccessFeature PaperReview
Perovskites as Catalysts in Advanced Oxidation Processes for Wastewater Treatment
Catalysts 2019, 9(3), 230; https://doi.org/10.3390/catal9030230 - 02 Mar 2019
Cited by 5
Abstract
Advanced oxidation processes (AOPs), based on the formation of highly reactive radicals are able to degrade many organic contaminants present in effluent water. In the heterogeneous AOPS the presence of a solid which acts as catalyst in combination with other systems (O3 [...] Read more.
Advanced oxidation processes (AOPs), based on the formation of highly reactive radicals are able to degrade many organic contaminants present in effluent water. In the heterogeneous AOPS the presence of a solid which acts as catalyst in combination with other systems (O3, H2O2, light) is required. Among the different materials that can catalyse these processes, perovskites are found to be very promising, because they are highly stable and exhibit a high mobility of network oxygen with the possibility of forming vacancies and to stabilize unusual oxidation states of metals. In this review, we show the fundaments of different kinds of AOPs and the application of perovskite type oxides in them, classified attending to the oxidant used, ozone, H2O2 or peroxymonosulfate, alone or in combination with other systems. The photocatalytic oxidation, consisting in the activation of the perovskite by irradiation with ultraviolet or visible light is also revised. Full article
(This article belongs to the Special Issue Catalysis by Metals on Perovskite-Type Oxides)
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