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Catalysts
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Catalytic Removal and Resource Utilization of NOx
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Catalytic Removal and Resource Utilization of NOx

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

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 14328

Special Issue Editor

Dr. Zhaoyang Fan

E-Mail Website
Guest Editor
College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
Interests: environmental catalysis; low temperature NOx abatement; SO2 resistance, ammonium bisulfate resistance; resource utilization of NOx

Special Issue Information

Dear Colleagues,

As the major gaseous pollutants, nitrogen oxides like N2O, NO, and NO2 can be originated from the combustion processes in both stationary and mobile sources. They contribute to a series of environmental concerns including the greenhouse effect, acid rain, and photochemical smog, etc., which pose a tremendous threat to human health as well as the ecosystem around us. Though the atmospheric environment is getting better in the last several decades, efficient de-NOx technologies with low energy consumption and environmental friendliness are still highly anticipated in the near future.

The selective catalytic reduction (SCR) of NOx by NH3 under medium and low-temperature range used to be the research hotspot, as evidenced by emerging catalysts with remarkable de-NOx activity, selectivity, and wide operating temperature window. However, the coexistence of H2O, SO2, and volatile organic compounds (VOCs) in practical circumstances poses a great challenge to the catalysts. In this context, the development of catalysts with high SO2 resistance, ammonium bisulfate (ABS) resistance, and the synergistic NOx-VOC removal capability would be of great importance. Meanwhile, the novel idea of transforming NOx into valuable N-containing chemicals instead of inert nitrogen is rather promising, where the utilization of solar energy or its derivative in other forms as the energy source would make this technology more intriguing.

With the aim of building better catalysts for a sustainable world, submissions to this special issue “Catalytic Removal and Resource Utilization of NOx” in the form of original research papers or short reviews regarding the following topics (Low-temperature NH3-SCR of NOx, SO2 resistance, Ammonium bisulfate (ABS) resistance, Synergistic NOx-VOCs removal, Resource utilization of NOx) are welcome.

Dr. Zhaoyang Fan
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • selective catalytic reduction
  • low-temperature denitrification
  • SO2 resistance
  • ammonium bisulfate resistance
  • synergistic NOx and VOCs removal
  • resource utilization of NOx

Published Papers (8 papers)

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Research

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23 pages, 4759 KiB  
Article
Selective Catalytic Reduction of NOx by CO over Cu(Fe)/SBA-15 Catalysts: Effects of the Metal Loading on the Catalytic Activity
by Monique S. Souza, Antonio J. Martins, Jackson Anderson S. Ribeiro, Adriana Campos, Alcineia C. Oliveira, Raí F. Jucá, Gilberto D. Saraiva, Marco Antonio M. Torres, Enrique Rodríguez-Castellón and Rinaldo S. Araujo
Catalysts 2023, 13(3), 527; https://doi.org/10.3390/catal13030527 - 04 Mar 2023
Cited by 4 | Viewed by 1747
Abstract
Mesoporous Cu(Fe)/SBA-15 catalysts were prepared with distinct metal loadings of ca. 2–10 wt.%. A detailed set of characterizations using X-ray diffraction (XRD), electron paramagnetic resonance (EPR), transmission electron microscopy (TEM), scanning electron microscopy coupled to energy dispersive spectroscopy (SEM-EDS), Mössbauer spectroscopy, X-ray photoelectron [...] Read more.
Mesoporous Cu(Fe)/SBA-15 catalysts were prepared with distinct metal loadings of ca. 2–10 wt.%. A detailed set of characterizations using X-ray diffraction (XRD), electron paramagnetic resonance (EPR), transmission electron microscopy (TEM), scanning electron microscopy coupled to energy dispersive spectroscopy (SEM-EDS), Mössbauer spectroscopy, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy was performed to correlate the relationship among structure, electronic properties and catalytic performances. All solids were evaluated in the selective catalytic reduction of NOx in the presence of CO (CO-SCR). The influence of the metal loadings on the overall activity indicated that introducing high amounts of Fe or Cu on the catalysts was beneficial to form either CuO or α-Fe2O3 clusters. Cux/SBA-15 series exhibited more efficient activity and poison-tolerant ability during CO-SCR reaction, in contrast to Fex/SBA-15. In spite of the Fe species introduced on SBA-15 having structural features similar to those of Cu ones, low interactions among Fe nanoparticles, silica and clusters impeded the high performances of Fe10/SBA-15. XPS revealed the Fe species in a more oxidized state, indicating the stability of the solid after the catalytic tests, in agreement with EPR and Raman spectroscopy. Cu8/SBA-15 worked better, being recyclable due to the interaction of the Cu2+ ions with SBA-15, avoiding the deactivation of the catalyst. Full article
(This article belongs to the Special Issue Catalytic Removal and Resource Utilization of NOx)
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13 pages, 5606 KiB  
Article
Enhanced SO2 Resistance of Cs-Modified Fe-HZSM-5 for NO Decomposition
by Fan Wang, Pengfei Liu, Jiaxue Guo, Kexin Xu, Yanrui Zhang, Yanhui Yi, Yimin Zhu and Li Wang
Catalysts 2022, 12(12), 1579; https://doi.org/10.3390/catal12121579 - 05 Dec 2022
Cited by 3 | Viewed by 932
Abstract
Direct decomposition of NO into N2 and O2 is an ideal technology for NOx removal. Catalyst deactivation by sulfur poisoning is the major obstacle for practical application. This paper focuses on strengthening the SO2 resistance of metal-exchanged HZSM-5 catalysts, [...] Read more.
Direct decomposition of NO into N2 and O2 is an ideal technology for NOx removal. Catalyst deactivation by sulfur poisoning is the major obstacle for practical application. This paper focuses on strengthening the SO2 resistance of metal-exchanged HZSM-5 catalysts, by investigating the metals, promoters, preparation methods, metal-to-promoter molar ratios, Si/Al ratios and metal loadings. The results show that in the presence of SO2 (500 ppm), Fe is the best compared with Co, Ni and Cu. Cs, Ba and K modification enhanced the low-temperature activity of the Fe-HZSM-5 catalyst for NO decomposition, which can be further improved by increasing the exchanged-solution concentration and Fe/Cs molar ratio or decreasing the Si/Al molar ratio. Interestingly, Cs-doped Fe-HZSM-5 exhibited a high NO conversion and low NO2 selectivity but a high SO2 conversion within 10 h of continuous operation. This indicates that Cs-Fe-HZSM-5 has a relatively high SO2 resistance. Combining the characterization results, including N2 physisorption, XRD, ICP, XRF, UV–Vis, XPS, NO/SO2-TPD, H2-TPR and HAADF-STEM, SO42− was found to be the major sulfur species deposited on the catalyst’s surface. Cs doping inhibited the SO2 adsorption on Fe-HZSM-5, enhanced the Fe dispersion and increased the isolated Fe and Fe-O-Fe species. These findings could be the primary reasons for the high activity and SO2 resistance of Cs-Fe-HZSM-5. Full article
(This article belongs to the Special Issue Catalytic Removal and Resource Utilization of NOx)
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20 pages, 4906 KiB  
Article
Phosphotungstic Acid-Modified MnOx for Selective Catalytic Reduction of NOx with NH3
by Hongyan Xue, Xiaoming Guo, Dongsen Mao, Tao Meng, Jun Yu and Zhen Ma
Catalysts 2022, 12(10), 1248; https://doi.org/10.3390/catal12101248 - 16 Oct 2022
Cited by 6 | Viewed by 1613
Abstract
H3PW12O40-modified MnOx catalysts (denoted as Mn-HPW) were used for NOx elimination with co-fed NH3. The optimal Mn-HPW0.02 catalyst exhibited over 90% NOx conversion at 90–270 °C. The incorporation of HPW increased [...] Read more.
H3PW12O40-modified MnOx catalysts (denoted as Mn-HPW) were used for NOx elimination with co-fed NH3. The optimal Mn-HPW0.02 catalyst exhibited over 90% NOx conversion at 90–270 °C. The incorporation of HPW increased the amount of Lewis acid sites of the catalyst for adsorbing NH3, and accelerated the reaction between the adsorbed NH3 species and gas-phase NOx, thus, increasing the low-temperature catalytic activity. The oxidation ability of the Mn catalyst was decreased due to the addition of HPW, thus, mitigating the overoxidation of the adsorbed NH3 species and improving the de-NOx activity and N2 selectivity in the high-temperature region. DRIFT results revealed that the NH3 species on Lewis and Brønsted acid sites, bridged nitrate, and bidentate nitrate were important species/intermediates for the reaction. NH3-SCR over the Mn and Mn-HPW0.02 catalysts obeyed the Eley–Rideal and Langmuir–Hinshelwood mechanisms, simultaneously, at 120 °C. Full article
(This article belongs to the Special Issue Catalytic Removal and Resource Utilization of NOx)
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15 pages, 3458 KiB  
Article
Assessment of a Euro VI Step E Heavy-Duty Vehicle’s Aftertreatment System
by Barouch Giechaskiel, Tommaso Selleri, Roberto Gioria, Anastasios D. Melas, Jacopo Franzetti, Christian Ferrarese and Ricardo Suarez-Bertoa
Catalysts 2022, 12(10), 1230; https://doi.org/10.3390/catal12101230 - 14 Oct 2022
Cited by 5 | Viewed by 2080
Abstract
The latest generation of heavy-duty vehicles (Euro VI step E) have to respect low emission limits both in the laboratory and on the road. The most challenging pollutants for diesel vehicles are NOx and particles; nevertheless, NH3 and N2O [...] Read more.
The latest generation of heavy-duty vehicles (Euro VI step E) have to respect low emission limits both in the laboratory and on the road. The most challenging pollutants for diesel vehicles are NOx and particles; nevertheless, NH3 and N2O need attention. In this study, we measured regulated and unregulated pollutants of a Euro VI step E Diesel vehicle. Samples were taken downstream of (i) the engine, (ii) the Diesel oxidation catalyst (DOC) and catalyzed Diesel particulate filter (cDPF), and (iii) the selective catalytic reduction (SCR) unit for NOx with an ammonia slip catalyst (ASC). In addition to typical laboratory and real-world cycles, various challenging tests were conducted (urban driving with low payload, high-speed full-load driving, and idling) at 23 °C and 5 °C. The results showed high efficiencies of the DOC, DPF, and SCR under most testing conditions. Cold start cycles resulted in high NOx emissions, while high-temperature cycles resulted in high particle emissions. The main message of this study is that further improvements are necessary, also considering possible reductions in the emission limits in future EU regulations. Full article
(This article belongs to the Special Issue Catalytic Removal and Resource Utilization of NOx)
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18 pages, 3497 KiB  
Article
Insights of Selective Catalytic Reduction Technology for Nitrogen Oxides Control in Marine Engine Applications
by Pierpaolo Napolitano, Leonarda Francesca Liotta, Chiara Guido, Cinzia Tornatore, Giuseppe Pantaleo, Valeria La Parola and Carlo Beatrice
Catalysts 2022, 12(10), 1191; https://doi.org/10.3390/catal12101191 - 08 Oct 2022
Cited by 9 | Viewed by 1875
Abstract
The international shipping industry is facing increasingly stringent limitations on nitrogen oxide (NOx) emissions. New solutions for reducing NOx emitted by marine engines need to be investigated to find the best technology. Selective Catalytic Reduction (SCR) is an advanced active [...] Read more.
The international shipping industry is facing increasingly stringent limitations on nitrogen oxide (NOx) emissions. New solutions for reducing NOx emitted by marine engines need to be investigated to find the best technology. Selective Catalytic Reduction (SCR) is an advanced active emissions control technology successfully used in automotive diesel engines; it could be applied to marine engines with ad-hoc solutions to integrate it in the exhaust of large engines. In this study, a commercial SCR was tested at the exhaust of a diesel engine in inlet gas conditions typical of a marine engine. The SCR system consisted of a custom monolith (provided by Hug-Engineering AG) that enabled seamless integration for a broad range of engine sizes; the active phases were V2O5 (3 wt%)-WO3 (7 wt%)-TiO2 (75 wt%). The monolith was studied at the laboratory scale for its in-depth chemical/physical characterization and by means of an intermediate-scale engine, reproducing the exhaust gas conditions of a full-scale marine engine. The system’s effectiveness in terms of NOx removal for the selected engine operating conditions was evaluated in a wide range of temperature and NOx emissions values and for different quantities of the reduction agent (AdBlue or ammonia) added to exhaust gases. The investigated technological solution resulted in efficient NOx emission control from a marine engine. Full article
(This article belongs to the Special Issue Catalytic Removal and Resource Utilization of NOx)
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11 pages, 2523 KiB  
Article
Enriching SO42− Immobilization on α-Fe2O3 via Spatial Confinement for Robust NH3-SCR Denitration
by Zhiwen Gu, Lijun Cheng, Chong Tan, Songil Sin, Chunkai Huang and Changjin Tang
Catalysts 2022, 12(9), 991; https://doi.org/10.3390/catal12090991 - 01 Sep 2022
Cited by 4 | Viewed by 2108
Abstract
The application of iron oxide to NH3-SCR is attractive but largely hindered by its poor acid properties, and surface sulfation is proven to be a prominent way of enhancing the acidity. As such, the method of enriching the sulfate species on [...] Read more.
The application of iron oxide to NH3-SCR is attractive but largely hindered by its poor acid properties, and surface sulfation is proven to be a prominent way of enhancing the acidity. As such, the method of enriching the sulfate species on iron oxide is crucial for improving the NH3-SCR performance. In the present study, by employing ammonium bisulfate (ABS) as the source of gaseous SO2 for the purpose of trapping, we reported an effective strategy for enhancing the SO42− immobilization on α-Fe2O3 catalyst via spatial confinement in a mesoporous SBA-15 framework. Interestingly, although the presence of the mesopore channel had an adverse effect on the ABS decomposition, which was expected to produce less available SO2, the measured SO42− immobilized on α-Fe2O3 in the mesoporous SBA-15 system was significantly greater than that of the regular SiO2, demonstrating the promoting effect of the spatial confinement on the SO42− enrichment. Further characterizations of the NH3-TPD, NO oxidation, and NH3-SCR performance tests proved that, as a result of the enhanced acidity, the enrichment of SO42− on α-Fe2O3 displayed a clear correlation with the SCR activity. The results of the present study provide an effective strategy for boosting the catalytic performance of iron oxide in NH3-SCR via SO42− enrichment. Full article
(This article belongs to the Special Issue Catalytic Removal and Resource Utilization of NOx)
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20 pages, 2939 KiB  
Article
Competitive Adsorption of NOx and Ozone on the Catalyst Surface of Ozone Converters
by Xiaolong Ji, Jean-Marc Clacens, Fabien Can, Antoinette Boréave, Laurent Veyre, Sonia Gil and Valérie Meille
Catalysts 2022, 12(7), 738; https://doi.org/10.3390/catal12070738 - 04 Jul 2022
Viewed by 1480
Abstract
Four catalysts—1%Pd-2%Mn/γ-Al2O3, 1%Pd/γ-Al2O3, 2%Mn/γ-Al2O3 and γ-Al2O3—were synthesized via a sol–gel method and characterized using various techniques to evaluate their physicochemical, textural, [...] Read more.
Four catalysts—1%Pd-2%Mn/γ-Al2O3, 1%Pd/γ-Al2O3, 2%Mn/γ-Al2O3 and γ-Al2O3—were synthesized via a sol–gel method and characterized using various techniques to evaluate their physicochemical, textural, surface and acidic properties. They were used in the catalytic transformation of ozone and nitrogen oxides using in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis. Different consecutive gas sequences were followed to unravel the poisoning role of nitrogen oxides and the possible reactivation by ozone. It has been proven that on palladium and manganese-based catalysts, the inhibition effect of nitrogen oxides was due to the formation of monodentate nitrites, monodentate, bidentate and bridged nitrates, which are difficult to desorb and decompose into gaseous NOx, either by oxidation or by thermal treatment. Interestingly, monodentate nitrites could be eliminated if the catalyst went through a co-adsorption of NOx and ozone prior to exposure in clean ozone flow. This transformation could be the reason why the catalytic conversion of ozone could return to its original value before the poison effect of nitrogen oxides. Full article
(This article belongs to the Special Issue Catalytic Removal and Resource Utilization of NOx)
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Review

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10 pages, 295 KiB  
Review
Materials Design for N2O Capture: Separation in Gas Mixtures
by Daniel Ballesteros-Plata, Juan Antonio Cecilia, Isabel Barroso-Martín, José Jiménez-Jiménez, Antonia Infantes-Molina and Enrique Rodríguez-Castellón
Catalysts 2022, 12(12), 1539; https://doi.org/10.3390/catal12121539 - 29 Nov 2022
Viewed by 1741
Abstract
The adsorption of greenhouse gases (GHG) as a method to reduce their emissions into the atmosphere is an alternative that is easier to implement industrially and cheaper than other existing technologies, such as chemical capture, cryogenic separation, or membrane separation. The vast majority [...] Read more.
The adsorption of greenhouse gases (GHG) as a method to reduce their emissions into the atmosphere is an alternative that is easier to implement industrially and cheaper than other existing technologies, such as chemical capture, cryogenic separation, or membrane separation. The vast majority of works found in the literature have focused their efforts on capturing CO2 as it is the largest GHG. However, although N2O emissions are not as large as CO2, the impact that N2O has on the stratosphere and climate is much larger in proportion, despite which there is not much research on N2O capture. Since both gases are usually emitted into the atmosphere together (along with other gases), it is necessary to design selective adsorbents capable of capturing and separating these gases from each other and from other gases, to mitigate the effects of climate change. This review aims to compile the existing information to date on porous adsorbents, the characteristics of the N2O adsorption processes and, above all, aims to focus the reader’s gaze on the importance of designing selective adsorbents for greenhouse gas mixtures. Full article
(This article belongs to the Special Issue Catalytic Removal and Resource Utilization of NOx)
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