NOx, VOCs (Volatile Organic Compounds) and Soot Emission Control in Catalysis, 2nd Edition

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

Deadline for manuscript submissions: closed (15 February 2024) | Viewed by 4798

Special Issue Editors


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Guest Editor
Institute of Nanostructured Materials, CNR - ISMN, Via Ugo La Malfa 153, 90146 Palermo, Italy
Interests: heterogeneous catalysis; pollution abatement (deNOx and VOC); temperature-programmed characterization; hydrogen production (dry reforming and partial oxidation of methane); PROX
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Guest Editor
Institute of Nanostructured Materials, Palermo Research Division, CNR - ISMN, Via Ugo La Malfa 153, 90146 Palermo, Italy
Interests: heterogeneous catalysts for CO2 valorization; dry and steam reforming of methane; autothermal reactions; thermal and photothermal activation; H2 purification; WGS reaction and PROX; CO2 hydrogenation; methanation reaction; CO2 electrochemical reduction; SOECs; SOFCs; catalytic devices for VOCs abatement (indoor and outdoor); CO and CH2 oxidation; NO SCR by NH3, HC, EtOH; antifouling and bactericidal activity of green materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This is the second edition of the Special Issue titled “NOx, VOCs (Volatile Organic Compounds) and Soot Emission Control in Catalysis, 2nd Edition”. Nowadays, the emission control in outdoor atmosphere, from diesel and gasoline vehicles, marine engines, fuel powered plants, and as well in indoor environments plays a fundamental role in order to slow down the global warming and preserve human health.

In this context, many governments with new severe legislations are trying to limit the environment pollution impact. Like Euro 7 regulation for vehicles, new standards, such as Tier II (valid outside Emission Control Areas, ECAs) and Tier III (applied only in ECAs) have been issued by the IMO (international maritime organization) of the United Nations in order to regulate NOx emissions for ships. Therefore, new formulations of NO SCR catalysts with high activity and N2 selectivity in the entire range of temperature of exhaust gases are needed. The catalytic performances become highly demanding when the aftertreatment of naval diesel engines fuelled by HFO (heavy fuel oil) is required, due to the high sulphur content.

The importance of catalytic abatement of VOCs, soot and NOx emissions is widely recognized. The goal is to obtain low cost, not toxic and efficient catalytic devices for unburned HC, VOCs and soot catalytic oxidation and for NOx abatement. Due to the limited resources of noble metals and the cost of the current technologies adopted for exhaust gas aftertreatment, it is necessary to find new efficient and cheap catalytic devices.

In this Special Issue, attention is paid to technological innovations to the emissions control from diesel, gasoline and, as well, from de-fossilized fuels powdered engines. The development of catalytic devices to control and purify the air quality indoors, such as in schools, gyms, meeting rooms is another aspect of the present Issue. In situ investigations, such as DRIFT studies or isotopic studies help in understanding the intermediates formation and reaction mechanisms of pollutants abatement. Structural, morphological, redox and electronic characterizations define the relationship between physico-chemical properties and catalytic performances.

Dr. Giuseppe Pantaleo
Dr. Leonarda Liotta
Guest Editors

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Keywords

  • VOCs
  • soot
  • indoor and outdoor pollution
  • sensors
  • NO SCR by HC or NH3/adBlue
  • engine operating conditions
  • monolithic and powder catalysts
  • supported noble metals
  • reducible oxides
  • poisoning effects and ageing phenomena
  • modelling of catalytic performance
  • CO2
  • H2O
  • SOx effects

Related Special Issue

Published Papers (5 papers)

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Research

20 pages, 5020 KiB  
Article
Role of Vanadium in Thermal and Hydrothermal Aging of a Commercial V2O5-WO3/TiO2 Monolith for Selective Catalytic Reduction of NOx: A Case Study
by Luca Consentino, Giuseppe Pantaleo, Valeria La Parola, Eleonora La Greca, Nunzio Gallì, Giuseppe Marcì, Roberto Fiorenza, Salvatore Scirè and Leonarda Francesca Liotta
Catalysts 2024, 14(4), 241; https://doi.org/10.3390/catal14040241 - 05 Apr 2024
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Abstract
In recent years, increased attention to air pollutants such as NOx has led the scientific community to focus meaningfully on developing strategies for NOx reduction. Selective catalytic reduction of NOx by ammonia (NO SCR by NH3) is currently [...] Read more.
In recent years, increased attention to air pollutants such as NOx has led the scientific community to focus meaningfully on developing strategies for NOx reduction. Selective catalytic reduction of NOx by ammonia (NO SCR by NH3) is currently the main method to remove NOx from diesel engine exhaust emissions. The catalysts with typical V2O5-WO3/TiO2 (VWTi) composition are widely used in NH3-SCR for their high NOx conversion activity, low cost, and robustness, especially concerning sulfur poisoning. However, in real diesel engine working conditions, the thermal and hydrothermal aging of catalysts can occur after several hours of operation at high temperature, affecting the catalytic performance. In this study, the stability of a commercial VWTi monolith, self-supported and containing glass fibers and bentonite in its matrix, was investigated as a case study. In laboratory conditions, NO SCR tests were performed for 50 h in the range of 150 to 350 °C. Subsequently, the VWTi monolith was thermally and hydrothermally aged at 600 °C for 6 h. The thermal aging increased the NOx conversion, especially at low temperature (<250 °C), while the hydrothermal aging did not affect the SCR. The differences in NOx conversion before and after aging were associated with the change in vanadium and tungsten oxide surface coverage and with the reduction in the surface area of catalysts. In order to correlate the change in SCR activity with the modifications occurring after aging processes, the monolithic samples were characterized by several techniques, namely XRD, SSA and pore analysis, TPR, XPS, Raman, TGA and SEM/EDX. Full article
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11 pages, 3272 KiB  
Article
Impact of Oxygen Storage Components in Prototype Pd-Based Three-Way Catalysts under Exhaust Conditions Relevant to Propane Engines
by Daekun Kim, Todd J. Toops, Ke Nguyen and Michael J. Lance
Catalysts 2023, 13(12), 1458; https://doi.org/10.3390/catal13121458 - 22 Nov 2023
Viewed by 800
Abstract
With increasing concerns about global warming, the push for sustainable and eco-friendly fuels is accelerating. Propane, recognized as liquefied petroleum gas or LPG, has garnered research interest as an alternative fuel due to its notable advantages, including a high-octane rating, reduced greenhouse gas [...] Read more.
With increasing concerns about global warming, the push for sustainable and eco-friendly fuels is accelerating. Propane, recognized as liquefied petroleum gas or LPG, has garnered research interest as an alternative fuel due to its notable advantages, including a high-octane rating, reduced greenhouse gas emissions, and potential cost-effectiveness. However, to realize its full potential as an alternative fuel it is essential to develop catalysts that efficiently handle emissions at low temperatures. In our research, we investigated three distinct palladium (Pd)-based three-way catalyst (TWC) formulations (PdRh, Pd-only, and Pd-OSC) to investigate the influence of typical TWC components rhodium (Rh) and oxygen storage components (OSC) in exhaust scenarios relevant to propane-fueled engines. Among these, the formulation containing oxygen storage components (Pd-OSC) showed the highest reactivity for both NO and C3H8 while minimizing performance degradation from hydrothermal aging (HTA). Notably, the temperature of 50% conversion (T50) for propane in the Pd-OSC fresh and HTA sample was lower by 30 °C and 13 °C, respectively, compared to the Pd-only sample, highlighting the role of oxygen storage materials in enhancing catalyst performance, even without dithering. Additionally, N2 physisorption showed that the Pd-OSC sample has a higher surface area and increased pore volume. This underscores the idea that OSC materials not only augment the catalyst’s porosity but also optimize reactant accessibility to active sites, thus elevating catalytic efficiency. In addition to evaluating performance, we further explored the performance and characteristics of the catalysts using catalytic probe reactions, such as water–gas shift and steam reforming reactions. Full article
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19 pages, 2873 KiB  
Article
Ni-BaMnO3 Perovskite Catalysts for NOx-Assisted Soot Oxidation: Analyzing the Effect of the Nickel Addition Method
by Salvador Montilla-Verdú, Álvaro Díaz-Verde, Verónica Torregrosa-Rivero and María José Illán-Gómez
Catalysts 2023, 13(11), 1453; https://doi.org/10.3390/catal13111453 - 20 Nov 2023
Viewed by 897
Abstract
In this study, we analyzed the role of a series of BaMn1−xNixO3 (x = 0, 0.2, and 0.4) mixed oxide catalysts, synthesized using the sol–gel method, in NOx-assisted diesel soot oxidation. ICP-OES, XRD, XPS, and H [...] Read more.
In this study, we analyzed the role of a series of BaMn1−xNixO3 (x = 0, 0.2, and 0.4) mixed oxide catalysts, synthesized using the sol–gel method, in NOx-assisted diesel soot oxidation. ICP-OES, XRD, XPS, and H2-TPR techniques were used for characterization and Temperature-Programmed Reaction experiments (NOx-TPR and Soot-NOx-TPR), and isothermal reactions at 450 °C (for the most active sample) were carried out to determine the catalytic activity. All samples catalyzed NO and soot oxidation at temperatures below 400 °C, presenting nickel-containing catalysts with the highest soot conversion and selectivity to CO2. However, the nickel content did not significantly modify the catalytic performance, and in order to improve it, two catalysts (5 wt % in Ni) were synthesized via the hydrothermal method (BMN2H) and the impregnation of nickel on a BaMnO3 perovskite as support (M5). The two samples presented higher activity for NO and soot oxidation than BMN2E (obtained via the sol–gel method) as they presented more nickel on the surface (as determined via XPS). BMN2H was more active than M5 as it presented (i) more surface oxygen vacancies, which are active sites for oxidation reactions; (ii) improved redox properties; and (iii) a lower average crystal size for nickel (as NiO). As a consequence of these properties, BMN2H featured a high soot oxidation rate at 450 °C, which hindered the accumulation of soot during the reaction and, thus, the deactivation of the catalyst. Full article
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13 pages, 4863 KiB  
Article
Structure-Sensitive Behavior of Supported Vanadia-Based Catalysts for Combustion of Soot
by Tomasz Rzadki, Piotr Legutko, Andrzej Adamski, Andrzej Kotarba and Janusz Trawczyński
Catalysts 2023, 13(11), 1406; https://doi.org/10.3390/catal13111406 - 30 Oct 2023
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Abstract
Catalytic performance of 3 and 5 wt.% of vanadia, supported on zirconia, zirconia-ceria, and zirconia-yttria, tested in the combustion of soot without and in the presence of NO was described. The catalysts were characterized by structural (XRD, RS) and functional (EPR, TPR) methods. [...] Read more.
Catalytic performance of 3 and 5 wt.% of vanadia, supported on zirconia, zirconia-ceria, and zirconia-yttria, tested in the combustion of soot without and in the presence of NO was described. The catalysts were characterized by structural (XRD, RS) and functional (EPR, TPR) methods. The effect of composition on the catalytic performance of the investigated systems in soot combustion was discussed in detail. Zirconia-supported vanadia was found to be the most active catalyst for soot oxidation characterized by the lowest combustion temperature (~375 °C) attributed to the maximal signal of conversion to the detected products. The relationship between the reducibility of surface oxovanadium species and their catalytic activity was established, revealing the involvement of the lattice oxygen in the combustion process. The importance of thermal treatment conditions and the nature of zirconia-based support determining the stability of specific oxovanadium entities on the catalyst surface was emphasized. Full article
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14 pages, 2797 KiB  
Article
An Assessment of Zeolite Framework Effect for Low-Temperature NOX Adsorbers
by Lidia Castoldi, Sara Morandi, Pierfrancesco Ticali, Roberto Matarrese and Luca Lietti
Catalysts 2023, 13(6), 962; https://doi.org/10.3390/catal13060962 - 01 Jun 2023
Cited by 1 | Viewed by 1103
Abstract
Pd-promoted zeolites (Y, ZSM-5, FER, SSZ-13) were prepared and characterized to analyze their properties as low-temperature NOx adsorbers. The samples were investigated by BET and XRD and by in situ FT-IR spectroscopy of CO and NO adsorption to probe the Pd sites [...] Read more.
Pd-promoted zeolites (Y, ZSM-5, FER, SSZ-13) were prepared and characterized to analyze their properties as low-temperature NOx adsorbers. The samples were investigated by BET and XRD and by in situ FT-IR spectroscopy of CO and NO adsorption to probe the Pd sites and the nature of the adsorbed NOx species. The NOx adsorption/desorption performances at low temperatures were examined by microreactor measurements upon NO/O2 adsorption followed by TPD in the presence of water and carbon dioxide. It was enlightened that: (i) the zeolite framework influences the Pd dispersion: the smaller the zeolite cage, the higher the Pd dispersion, irrespective of the Si/Al ratio. Accordingly, the following Pd dispersion order has been observed, inversely to the zeolite cage size: Pd/SSZ-13 > Pd/ZSM-5 ~ Pd/FER >> Pd/Y; (ii) Pd is present as isolated Pdn+ species and in PdOx particles; (iii) the Pd dispersion governs the NOx storage capacity: the smaller the zeolite cage, the higher the Pd dispersion and the storage capacity; (iv) NO adsorbs mainly in the form of Pd nitrosyls and nitrates; (v) NO desorption occurs both at a temperature below 200 °C and in a high-temperature range (near 350 °C). Full article
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