Environmental Catalysis for Air Pollution Applications

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

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 28469

Special Issue Editors


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Guest Editor
Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
Interests: air pollution; indoor air quality; photocatalysis for air purification and CO2 reduction; environmental catalysis
Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
Interests: air pollution; photocatalysis; electrocatalysis for CO2 reduction

Special Issue Information

Dear Colleagues,

Air pollution poses a great threat to the health of an increasing number of the world’s population, as data show that above ninety percent of the global population live in areas where pollution levels exceed WHO guidelines. To achieve a sustainable and livable society, strict regulatory policies and control measures must be implemented immediately. Environmental catalysis has attracted increasing attention for air pollutant mitigation, including NOx, VOCs, and formaldehyde, due to its mild operation conditions and eco-friendly attributes.

By environmental catalysis we primarily mean photocatalysis and room/low temperature catalysis processes. With light or heat as energy inputs, catalysts can be excited and trigger O2 activation to produce various reactive oxygen species; they are primarily responsible for adsorbed gas pollutant oxidation and thereby achieving ambient air purification.

In this regard, transitional metal oxides and their supported noble metal nanoparticles are the most popular and promising catalysts worthy of study because of their excellent performances with regard to O2 activation. Many strategies have been developed to tune the particle size (even down to the single atom scale), morphology, and exposed facet to manipulate the electronic structure and expose more active sites for better adsorption and reaction.

Above all, environmental catalysis provides a supplement to source control methods for ambient air purification featuring low energy consumption and high efficiency. Catalyst design, synthesis, characterization, and optimization are the core to this technology and are of prime importance to this Special Issue.

Prof. Dr. Yu Huang
Dr. Qian Zhang
Guest Editors

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Keywords

  • environmental catalysis
  • photocatalysis
  • air purification
  • VOCs removal
  • nanomaterial catalysts
  • CO2 reduction and utilization

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Published Papers (10 papers)

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Research

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16 pages, 6027 KiB  
Article
Photocatalytic NOx Removal in Bismuth-Oxyhalide (BiOX, X = I, Cl) Cement-Based Materials Exposed to Outdoor Conditions
by Magaly Y. Nava-Núñez, Eva Jimenez-Relinque, Azael Martínez-de la Cruz and Marta Castellote
Catalysts 2022, 12(9), 982; https://doi.org/10.3390/catal12090982 - 31 Aug 2022
Cited by 5 | Viewed by 1798
Abstract
Cement-based materials modified with 3D BiOX (X = I, Cl) microspheres at different percentages (1, 5 and 10% by weight of the cement binder) were prepared to investigate the durability of the photocatalytic NOx removal under outdoor conditions. Weathering—corresponding to a period [...] Read more.
Cement-based materials modified with 3D BiOX (X = I, Cl) microspheres at different percentages (1, 5 and 10% by weight of the cement binder) were prepared to investigate the durability of the photocatalytic NOx removal under outdoor conditions. Weathering—corresponding to a period of 13 months outdoors—was studied in terms of NO removal efficiency under visible and UVA light irradiation for BiOI and BiOCl mortars, respectively. Following this period, the samples were protected from the environment for four years, and NOx removal and selectivity to nitrates were assessed. BiOI and BiOCl mortar samples were initially photocatalytically active; NOx removal performance increased as BiOX content increased. There was good photocatalyst dispersion, and compressive strength was not significantly impacted. The BiOI mortars had nearly completely lost their activity after 5 years from casting, whereas mortars containing 10% BiOCl had maintained about 7% of initial performance. The results suggest that mortar deactivation is due to surface dirt and nitrates accumulation from NOx oxidation on the surface rather than carbonation. An internal self-deactivation mechanism that affects BiOI in mortar matrix has also been postulated. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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11 pages, 4638 KiB  
Article
NO Reduction Reaction by Kiwi Biochar-Modified MnO2 Denitrification Catalyst: Redox Cycle and Reaction Process
by Hao Fan, Zhenxing Shen, Xiuru Wang, Jie Fan, Jian Sun and Jiaxiang Sun
Catalysts 2022, 12(8), 870; https://doi.org/10.3390/catal12080870 - 7 Aug 2022
Cited by 2 | Viewed by 1841
Abstract
NO is a major environmental pollutant. MnO2 is often used as a denitrification catalyst with poor N2 selectivity and weak SO2 resistance. Kiwi twig biochar was chosen to modify MnO2 samples by using the hydrothermal method. The NO conversion [...] Read more.
NO is a major environmental pollutant. MnO2 is often used as a denitrification catalyst with poor N2 selectivity and weak SO2 resistance. Kiwi twig biochar was chosen to modify MnO2 samples by using the hydrothermal method. The NO conversion rates of the biochar-modified samples were >90% at 125–225 °C. Kiwi twig biochar made the C2MnO2 sample with a larger specific surface area, a higher number of acidic sites and Oβ/Oα molar ratio, leading to more favorable activity at high temperatures and better SO2 resistance. Moreover, the inhibition of the NH3 oxidation reaction and the Mn3+ → Mn4+ process played a crucial role in the redox cycle. What was more, Brønsted acidic sites present on the C1MnO2 sample participate in the reaction more rapidly. This study identified the role of biochar in the reaction process and provides a reference for the wide application of biochar. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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11 pages, 1366 KiB  
Article
Synthesis of Vanadium-Containing Catalytically Active Phases for Exhaust Gas Neutralizers of Motor Vehicles and Industrial Enterprises
by Bolatbek Khussain, Alexandr Brodskiy, Alexandr Sass, Kenzhegul Rakhmetova, Vladimir Yaskevich, Valentina Grigor’eva, Altay Ishmukhamedov, Anatoliy Shapovalov, Irina Shlygina, Svetlana Tungatarova and Atabek Khussain
Catalysts 2022, 12(8), 842; https://doi.org/10.3390/catal12080842 - 31 Jul 2022
Cited by 11 | Viewed by 1866
Abstract
The catalytically active vanadium-containing system of γ-Al2O3 was studied using a wide range of physical and chemical methods, depending on the synthesis conditions. It is shown that the vanadium-containing system includes several complexes with different thermal stabilities and catalytic activities. [...] Read more.
The catalytically active vanadium-containing system of γ-Al2O3 was studied using a wide range of physical and chemical methods, depending on the synthesis conditions. It is shown that the vanadium-containing system includes several complexes with different thermal stabilities and catalytic activities. Low-active complexes are destroyed with the formation of more active ones based on V2O5 oxide, as the temperature of heat treatment increases. It can be assumed that V2O5 oxide has the decisive role in its catalytic activity. It was concluded that the vanadium-containing catalytic system on aluminium oxide, in the studied temperature range, is thermally stable and shows high activity not only in the reduction of nitrogen oxides but also in the oxidation of hydrocarbons (even of the most difficult ones, such as oxidizable methane). These properties of the system make it quite promising in the field of application for the purification of the exhaust gases of motor transport and industrial enterprises with environmentally harmful components, as well as for understanding the mechanism of the action of the catalysts in these processes, which is very important for solving the problems of decarbonization and achieving carbon neutrality. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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13 pages, 8530 KiB  
Article
The Effect of Potassium Inclusion in a Silver Catalyst for N2O-Mediated Oxidation of Soot in Oxidising Exhaust Gases
by Anna Cooper, Stan Golunski and Stuart H. Taylor
Catalysts 2022, 12(7), 753; https://doi.org/10.3390/catal12070753 - 7 Jul 2022
Viewed by 1587
Abstract
It has previously been shown that an Ag/CZA catalyst can simultaneously remove NOx and soot from an oxygen-rich exhaust gas at low temperatures, by utilising the N2O generated preferentially during incomplete NOx reduction. Here, we examine the effect of reformulating the [...] Read more.
It has previously been shown that an Ag/CZA catalyst can simultaneously remove NOx and soot from an oxygen-rich exhaust gas at low temperatures, by utilising the N2O generated preferentially during incomplete NOx reduction. Here, we examine the effect of reformulating the catalyst to include potassium, which is a known promoter of soot combustion. On including 2 wt% K, NOx-reduction occurs both in the absence and presence of soot, but the N2O formed does not play a part in the oxidation of soot. At higher K loadings (5, 10 and 15 wt%), NOx reduction is almost completely disabled, and only contributes to the activity of the catalyst containing 5 wt% K when tested in the presence of soot. At a loading of 20 wt% K, the potassium phase segregates, leaving NO and NH3 adsorption sites exposed. In the absence of soot, this catalyst can remove NOx by reduction on the Ag/CZA component and through nitration of the potassium phase. Although the presence of potassium lowers the onset temperature for soot oxidation to within the range of NOx reduction over Ag/CZA, the mobile K species prevents the desirable C+N2O reaction. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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17 pages, 9347 KiB  
Article
Unraveling the Reaction Mechanism of HCHO Catalytic Oxidation on Pristine Co3O4 (110) Surface: A Theoretical Study
by Rong Li, Tingting Huang, Yu Huang, Meijuan Chen, Shun-cheng Lee, Wingkei Ho and Junji Cao
Catalysts 2022, 12(5), 560; https://doi.org/10.3390/catal12050560 - 19 May 2022
Cited by 6 | Viewed by 2600
Abstract
Various reaction mechanisms for the catalytic degradation of formaldehyde (HCHO) remain to be debated. Density functional theory (DFT) was applied to investigate whether the catalytic oxidation of HCHO on pristine Co3O4 (110) surface follows the Mars-van Krevelen (MvK) mechanism or [...] Read more.
Various reaction mechanisms for the catalytic degradation of formaldehyde (HCHO) remain to be debated. Density functional theory (DFT) was applied to investigate whether the catalytic oxidation of HCHO on pristine Co3O4 (110) surface follows the Mars-van Krevelen (MvK) mechanism or the Langmuir–Hinshelwood (L-H) mechanism. Firstly, HCHO and O2 co-adsorb on the surface and two H atoms from HCHO are peculiarly prone to transfer to O2, forming CO and HOOH. For the MvK mechanism, CO2 is generated through CO grabbing a lattice oxygen. Meanwhile, the O–O bond of HOOH is broken into two OH groups. One OH fills the oxygen vacancy and its H atom moves to another OH group for H2O formation. For the L-H mechanism, CO directly obtains one OH group to generate COOH. Subsequently, the H atom of COOH transfers to another OH group along with CO2 and H2O generation. Both two mechanisms exhibit a similar maximum activation barrier. The lattice oxygen in the MvK mechanism and the surface-absorbed OH group in the L-H mechanism are the key reactive oxygen species. The small difference in energetic span further suggests that the catalytic cycle through the two mechanisms is feasible. This theoretical study provides new insight into the catalytic reaction path of HCHO oxidation on pristine Co3O4 surface. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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16 pages, 6768 KiB  
Article
Enhanced Performance of Supported Ternary Metal Catalysts for the Oxidation of Toluene in the Presence of Trichloroethylene
by Tiantian Dong, Kun Liu, Ruyi Gao, Hualian Chen, Xiaohui Yu, Zhiquan Hou, Lin Jing, Jiguang Deng, Yuxi Liu and Hongxing Dai
Catalysts 2022, 12(5), 541; https://doi.org/10.3390/catal12050541 - 16 May 2022
Cited by 4 | Viewed by 2732
Abstract
Chlorinated volatile organic compounds (CVOCs), even in small quantities, can cause Pt-based catalyst poisoning. Improving the low-temperature chlorine resistance of catalysts is of vital importance for industrial application, although it remains challenging. Considering actual industrial production, a TiO2-supported ternary metal catalyst [...] Read more.
Chlorinated volatile organic compounds (CVOCs), even in small quantities, can cause Pt-based catalyst poisoning. Improving the low-temperature chlorine resistance of catalysts is of vital importance for industrial application, although it remains challenging. Considering actual industrial production, a TiO2-supported ternary metal catalyst was prepared in this work to study the catalytic oxidation of multicomponent VOCs (toluene and trichloroethylene (TCE)). Among all of the samples, PtWRu/TiO2 and PtWCr/TiO2 exhibited the best catalytic performance for toluene oxidation. In the mixed VOC oxidation, the PtWCr/TiO2 sample showed the best catalytic activity for toluene combustion (a toluene conversion of 90% was achieved at 258 °C and a space velocity of 40,000 mL g−1 h−1, and the specific reaction rate and turnover frequency at 215 °C were 44.9 × 10−6 mol gPt−1 s−1 and 26.2 × 10−5 s−1). The PtWRu/TiO2 sample showed the best catalytic activity for TCE combustion (a TCE conversion of 90% was achieved at 305 °C and a space velocity of 40,000 mL g−1 h−1, and the specific reaction rate and turnover frequency at 270 °C were 9.0 × 10−6 mol gPt−1 s−1 and 7.3 × 10–5 s−1). We concluded that the ternary metal catalysts could greatly improve chlorine desorption by increasing the active lattice oxygen mobility and surface acidity, thus reducing chlorinated byproducts and other serious environmental pollutants. This work may serve as a reasonable design reference for solving more practical industrial production emissions of multicomponent VOCs. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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14 pages, 3763 KiB  
Article
Low-Temperature O3 Decomposition over Pd-TiO2 Hybrid Catalysts
by Houcine Touati, Afef Mehri, Fathi Karouia, Frédéric Richard, Catherine Batiot-Dupeyrat, Stéphane Daniele and Jean-Marc Clacens
Catalysts 2022, 12(4), 448; https://doi.org/10.3390/catal12040448 - 18 Apr 2022
Cited by 5 | Viewed by 3371
Abstract
In aircraft and spacecraft, outside air is not directly fed to the passenger because it contains ozone at elevated altitudes. The decomposition of low concentration ozone in the air was carried out at 25 °C by catalytic oxidation on Pd-based catalysts supported on [...] Read more.
In aircraft and spacecraft, outside air is not directly fed to the passenger because it contains ozone at elevated altitudes. The decomposition of low concentration ozone in the air was carried out at 25 °C by catalytic oxidation on Pd-based catalysts supported on a high surface area hybrid TiO2. The use of these hybrid catalysts has shown a beneficial effect, both on the catalytic activity and on the catalyst stability. Kinetic studies showed that the most promising catalytic phase (Pd/TiO2_100) was the one obtained from the TiO2 support containing the lowest content of citrate ligands and leading to small Pd particles (around 4 nm). The effect of catalyst synthesis on the decomposition of O3 gas (15 ppm) in a dry and humid (HR = 10%) stream in a closed environment such as aircraft or spacecraft was also investigated in this study and further elucidated by detailed characterizations. It was shown that the system could be used as an effective treatment for air coming from outside. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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Review

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17 pages, 1086 KiB  
Review
The Application of Mineral Kaolinite for Environment Decontamination: A Review
by Meijuan Chen, Tongxi Yang, Jichang Han, Yang Zhang, Liyun Zhao, Jinghan Zhao, Rong Li, Yu Huang, Zhaolin Gu and Jixian Wu
Catalysts 2023, 13(1), 123; https://doi.org/10.3390/catal13010123 - 5 Jan 2023
Cited by 23 | Viewed by 4153
Abstract
Kaolinite clay mineral with a layered silicate structure is an abundant resource in China. Due to its advantages of excellent stability, high specific surface area and environmental friendliness, kaolinite is widely used in environment decontamination. By using kaolinite as a carrier, the photocatalytic [...] Read more.
Kaolinite clay mineral with a layered silicate structure is an abundant resource in China. Due to its advantages of excellent stability, high specific surface area and environmental friendliness, kaolinite is widely used in environment decontamination. By using kaolinite as a carrier, the photocatalytic technology in pure photocatalysts of poor activities, narrow spectral responses, and limited electron transport can be overcome, and the nano-Ag disinfectant’s limitation of the growth and aggregation of nanoparticles is released. Moreover, pure kaolinite used as an adsorbent shows poor surface hydroxyl activity and low cation exchange, leading to the poor adsorption selectivity and easy desorption of heavy metals. Current modification methods including heat treatment, acid modification, metal modification, inorganic salt modification, and organic modification are carried out to obtain better adsorption performance. This review systematically summarizes the application of kaolinite-based nanomaterials in environmental decontamination, such as photocatalytic pollutant degradation and disinfection, nano silver (Ag) disinfection, and heavy metal adsorption. In addition, applications on gas phase pollutant, such as carbon dioxide (CO2), capture and the removal of volatile organic compounds (VOCs) are also discussed. This study is the first comprehensive summary of the application of kaolinite in the environmental field. The review also illustrates the efficiency and mechanisms of coupling naturally/modified kaolinite with nanomaterials, and the limitation of the current use of kaolinite. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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18 pages, 2638 KiB  
Review
Mitigation of Air Pollutants by UV-A Photocatalysis in Livestock and Poultry Farming: A Mini-Review
by Myeongseong Lee, Jacek A. Koziel, Peiyang Li and William S. Jenks
Catalysts 2022, 12(7), 782; https://doi.org/10.3390/catal12070782 - 15 Jul 2022
Cited by 3 | Viewed by 2872
Abstract
Ultraviolet (UV)-based photocatalysis has been the subject of numerous investigations focused on mitigating undesirable pollutants in the gas phase. Few works report on applications beyond the proof of the concept. Even less is known about the current state of the art of UV [...] Read more.
Ultraviolet (UV)-based photocatalysis has been the subject of numerous investigations focused on mitigating undesirable pollutants in the gas phase. Few works report on applications beyond the proof of the concept. Even less is known about the current state of the art of UV photocatalysis in the context of animal agriculture. A growing body of research published over the last 15 years has advanced the knowledge and feasibility of UV-A photocatalysis for swine and poultry farm applications. This review paper summarizes UV-A photocatalysis technology’s effectiveness in mitigating targeted air pollutants in livestock and poultry farms. Specifically, air pollutants include odor, odorous VOCs, NH3, H2S and greenhouse gases (CO2, CH4, N2O). We trace the progression of UV-A photocatalysis applications in animal farming since the mid-2000 and developments from laboratory to farm-scale trials. In addition, this review paper discusses the practical limitations and outlines the research needs for increasing the technology readiness and practical UV application in animal farming. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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13 pages, 2017 KiB  
Review
Bismuth Sillenite Crystals as Recent Photocatalysts for Water Treatment and Energy Generation: A Critical Review
by Oussama Baaloudj, Hamza Kenfoud, Ahmad K. Badawi, Achraf Amir Assadi, Atef El Jery, Aymen Amine Assadi and Abdeltif Amrane
Catalysts 2022, 12(5), 500; https://doi.org/10.3390/catal12050500 - 29 Apr 2022
Cited by 42 | Viewed by 3956
Abstract
Photocatalysis has been widely studied for environmental applications and water treatment as one of the advanced oxidation processes (AOPs). Among semiconductors that have been employed as catalysts in photocatalytic applications, bismuth sillenite crystals have gained a great deal of interest in recent years [...] Read more.
Photocatalysis has been widely studied for environmental applications and water treatment as one of the advanced oxidation processes (AOPs). Among semiconductors that have been employed as catalysts in photocatalytic applications, bismuth sillenite crystals have gained a great deal of interest in recent years due to their exceptional characteristics, and to date, several sillenite material systems have been developed and their applications in photoactivity are under study. In this review paper, recent studies on the use of Bi-based sillenites for water treatment have been compiled and discussed. This review also describes the properties of Bi-based sillenite crystals and their advantages in the photocatalytic process. Various strategies used to improve photocatalytic performance are also reviewed and discussed, focusing on the specific advantages and challenges presented by sillenite-based photocatalysts. Furthermore, a critical point of certain bismuth catalysts in the literature that were found to be different from that reported and correspond to the sillenite form has also been reviewed. The effectiveness of some sillenites for environmental applications has been compared, and it has demonstrated that the activity of sillenites varies depending on the metal from which they were produced. Based on the reviewed literature, this review summarizes the current status of work with binary sillenite and provides useful insights for its future development, and it can be suggested that Bismuth sillenite crystals can be promising photocatalysts for water treatment, especially for degrading and reducing organic and inorganic contaminants. Our final review focus will emphasize the prospects and challenges of using those photocatalysts for environmental remediation and renewable energy applications. Full article
(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)
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