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 NO_x 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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• 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

• DeNOx Systems and VOCs (Volatile Organic Compounds) for Pollution Abatement in Catalysis in Catalysts (5 articles)

Title: Role of Vanadium in thermal and hydrothermal aging of commercial V2O5-WO3/TiO2 monolith: effect on morphology and catalytic activity.
Authors: L. Consentino1, G. Pantaleo1*, V. La Parola1, G. Marcì2, L.F. Liotta1*
Affiliation: 1Istituto per lo Studio dei Materiali Nanostrutturati (ISMN)-CNR, Via Ugo La Malfa 153, 90146 Palermo, Italy. 2“Schiavello-Grillone” Photocatalysis Group, Department of Engineering, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy.
Abstract: In the last years the increased attention to air pollutant as NOx has led the scientific community to focus meaningfully on developing strategies for NOx reduction. Selective Catalytic Reduction of NOx by ammonia (NH3-SCR) is currently the main method to remove NOx from exhausts diesel engines. 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, thermal and hydrothermal aging of catalysts due to high temperature can occur, usually affecting the catalytic performances. In this study a commercial VWTi monolith as received and after thermal or hydrothermal aging was investigated by aging at 600 °C for 6 hours in dry or wet conditions. 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 of vanadium and tungsten oxides surface coverage and with the reduction of surface area of catalysts. The monoliths were characterized by BET, TPR, TGA, XPS and SEM/EDX in order to correlate the change in SCR activity with the modifications occurring after aging processes

Title: Ni-BaMnO3 perovskite catalysts for NOx-assisted Soot Oxidation: analyzing the effect for nickel addition method.
Authors: María-José Illán-Gómez
Affiliation: Carbon Materials and Environment Research Group, Department of Inorganic Chemistry, Faculty of Science, University of Alicante San Vicente del Raspeig, 03690 Alicante, Spain

Title: Sulfur and Water Resistance of Carbon-Based Catalysts for Low-Temperature Selective Catalytic Reduction of NOx：A Review
Authors: Zhaoying Zheng 1, 2, Xiangdong Xing 1, 2, *, Shan Ren 3, *, Sunxuan Wang 4, Zhenghua Shen 1, 2, Xu Jiang 5
Affiliation: 1.School of Metallurgy Engineering, Xi’an University of Architecture and Technology, ShaanXi, Xi’an 710055, China. 2.Research Center of Metallurgical Engineering Technology of Shaanxi Province, ShaanXi, Xi’an 710055, China. 3.College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China 4.Shaanxi Institute for Food and Drug Control, Xi’an 710065, PR China 5.Research Institute of Energy Chemical Industry, Xianyang Vocational Technical College, Xianyang 712000, PR China
Abstract: Due to the advantages of good adsorption performance, well-developed porous structure and large specific surface area, carbon-based materials have broad application prospects in selective catalytic reduction of NOx with NH3 (NH3-SCR). However, overcoming the poor resistance of carbon-based catalysts to the poisons of H2O and SO2 remains a great challenge. This review introduces the reaction mechanism of carbon-based catalysts and the poisoning mechanism of SO2 and H2O. Strategies to improve the SO2 and H2O resistance of carbon-based catalysts in recent years are summarized through catalyst support, modification, structure, preparation methods and reaction conditions. Prospecting the further development of carbon-based catalysts in NOx low-temperature SCR. This study provides a new insight and guidance into the design of low-temperature SCR catalysts resistant to SO2 and H2O in the future.

Title: Co- modified SBA-15 purification processes-effect of precursor and method of preparation
Authors: Bozhidar Grahovski1, Jean-Luc Blin 2, Bénédicte Lebeau 3,4, Anton Naydrnov, Ralitsa Velinova, Lionel Richaudeau2, Hristo Kolev 1, Laure Michelin, 3,4, Iliyana Yordanova 1, Krasimir Tenchev 1 , Silviy
Affiliation: 1.Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria; Université de Lorraine/CNRS, L2CM, UMR7053, CEDEX, F-54506 Vandoeuvre-lès-Nancy, France; 2.Université de Haute Alsace (UHA)/CNRS, IS2M, UMR 7361, CEDEX, 68093 Mulhouse, France; 3.Université de Strasbourg, F-6700 Strasbourg, France 4.Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria;
Abstract: The paper will report a new data on the structural and catalytic properties of series of mono-component cobalt catalysts supported on SBA-15, prepared by different precursors and characterized by HRTEM, TPR, XRD, XPA, Uv-vis before and after reaction. The catalysts performance is evaluated by tests on combustion of methane, propane and n-hexane. It was established that the preparation of the Co-SBA-15 catalysts by different precursors does not change significantly the mesoporous structure. The highest activity of the mono-component cobalt sample obtained by acetate precursor is explained by its higher reducibility as result of lower interaction of the cobalt oxide with the SBA-15.