Search Results (57)

The selective catalytic reduction of NO_x with CH₄ (CH₄-SCR) holds the potential to simultaneously abate harmful NO_x and CH₄ greenhouse gases. In this study, a series of bimetallic M-In/H-SSZ-39 catalysts (where M represents Cr, Co, Ce, and Fe) were prepared via an ion exchange method and subsequently evaluated for their CH₄-SCR activity. The influences of the preparation parameters, including the metal ion concentration and calcination temperature, as well as the operating conditions, such as the CH₄/NO ratio, O₂ concentration, water vapor content, and gas hourly space velocity (GHSV), on the catalytic activity of the optimal Cr-In/H-SSZ-39 catalyst were meticulously examined. The results revealed that the Cr-In/H-SSZ-39 catalyst exhibited peak CH₄-SCR catalytic performance when the Cr(NO₃)₃ concentration was 0.0075 M, the In(NO₃)₃ concentration was 0.066 M, and the calcination temperature was 500 °C. Under optimal operating conditions, namely GHSV of 10,000 h⁻¹, 400 ppm NO, 800 ppm CH₄, 15 vol% O₂, and 6 vol% H₂O, the NO_x conversion rate reached 93.4%. To shed light on the excellent performance of Cr-In/H-SSZ-39 under humid conditions, a comparative analysis of the crystalline phase, chemical composition, pore structure, surface chemical state, surface acidity, and redox properties of Cr-In/H-SSZ-39 and In/H-SSZ-39 was conducted. The characterization results indicated that the incorporation of Cr into In/H-SSZ-39 enhanced its acidity and also facilitated the generation of InO⁺ active species, which promoted the oxidation of NO and the activation of CH₄, respectively. A synergistic effect was observed between Cr and In species, which significantly improved the redox properties of the catalyst. Consequently, the activated CH₄ could further interact with InO⁺ to produce carbon-containing intermediates such as HCOO⁻, which ultimately reacted with nitrate-based intermediates to yield N₂, CO₂, and H₂O. Full article

Platinum was supported on ZSM5 at loadings from 0.1 to 1 wt% and tested for the Selective Catalytic Reduction of NO with H₂ under excess O₂ in a fixed bed reactor to address the issue of NO_x emission abatement from H₂-fueled internal combustion engines avoiding the additional devices for urea storage and injection. To reduce the undesired NO oxidation to NO₂, which is activated by platinum at T > 200 °C, the 0.1%Pt/ZSM5 catalyst was further promoted with sodium. 5 wt% loading of Na strongly inhibited the NO oxidation while giving only a limited impact on the H₂-SCR activity. Unpromoted and Na-promoted catalysts were characterized by XRD, SEM/EDX, N₂ physisorption, and NH₃-TPD to investigate the morphological, structural, and acid properties; H₂ pulse chemisorption and DRIFTS of CO chemisorption were used to investigate the nature of Pt active species. Steady-state and transient operando DRIFTS experiments under NO+H₂+O₂ flow were employed to identify the adsorbed NO_x species interacting with H₂, and reaction intermediates as a function of the reaction conditions. The formation of ammonium intermediates via the reduction of surface nitrate species, playing a key role in H₂-SCR catalyzed by 0.1Pt/ZSM5, was preserved at low Na load whilst NO₂ formation was largely inhibited. Full article

Air pollution is the world’s greatest environmental health risk. Pollutants that pose large health concerns are particulate matter (PM_2.5 and PM₁₀), ozone (O₃), carbon monoxide (CO), nitrogen dioxide (NO₂), and sulphur dioxide (SO₂). These compounds (especially PM_2.5 and PM₁₀) contribute to the onset of diseases, such as respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease (COPD), or lung cancer) and cardiovascular diseases. Abatement interventions are implemented to reduce air pollution and thereby the risk of these diseases. This systematic review examined the published scientific evidence on the cost-effectiveness of strategies aimed at reducing or controlling air pollution and assessed the reporting quality of included studies. It employed rigorous data extraction and quality scoring procedures to ensure the reliability and validity of our findings. Overall, there is substantial evidence supporting the cost-effectiveness of interventions aimed at reducing air pollution. Seventy-four studies and four policy reports were included in this review. Predominantly, cost–benefit analyses have been reported (n = 40), reflecting the multisectoral impacts and associated costs of air pollution. Only four cost–utility analyses were found, indicating the need for more research within this domain. Additionally, eight articles reported one or more non-economic results. Thirty-nine studies focused on particulate matter (PM), and eleven focused on nitrogen oxides (NOx). The quality assessment yielded moderate results. The heterogeneity of studies and moderate quality of reporting make it difficult to compare results and draw definitive conclusions. Full article

The present study aims to investigate a Pd catalyst on a complex multi-oxide medium-entropy support interlayer La₂O₃-CeO₂-ZrO₂-Al₂O₃ and its possible use as catalysts for methane abatement applications. The low-temperature N₂-adsorption, XRD, TEM, XPS, TPD, and TPR techniques were used to characterize the catalyst. The palladium deposition on the supports leads to the formation of PdO. After the catalytic tests, the metal-Pd phase was observed. The complete oxidation of methane on Pd/La-Ce-Zr-Al catalyst takes place at temperatures above 250 °C, and in the presence of water vapor, the reaction temperature increases to about 70 °C. The careful choice of constituent oxides provides a balance between structural stability and flexibility. The alumina and lanthanum oxide ensure the high specific surface area, while the simultaneous presence of zirconia and ceria leads to the formation of a mixed-oxide phase able to interact with palladium ions by incorporating and de-incorporating them at different conditions. The mechanism of Mars–van Kerevelen was considered as the most probable for the reaction of complete methane oxidation. The possibility of the practical application of Pd-modified La-Ce-Zr-Al catalyst is evaluated. The use of a mix of multiple rare and abundant oxides makes the proposed catalyst a cost-effective alternative. Full article

Addressing climate change requires a deeper understanding of all greenhouse gases, yet nitrous oxide (N₂O)—despite its significant global warming potential—remains underrepresented in sustainability analysis and policy discourse. The paper examines N₂O emissions from an environmental, social, and governance (ESG) standpoint with a combination of econometric and machine learning specifications to uncover global trends and policy implications. Results show the overwhelming effect of ESG factors on emissions, with intricate interdependencies between economic growth, resource productivity, and environmental policy. Econometric specifications identify forest degradation, energy intensity, and income inequality as the most significant determinants of N₂O emissions, which are in need of policy attention. Machine learning enhances predictive power insofar as emission drivers and country-specific trends are identifiable. Through the integration of panel data techniques and state-of-the-art clustering algorithms, this paper generates a highly differentiated picture of emission trends, separating country groups by ESG performance. The findings of this study are that while developed nations have better energy efficiency and environmental governance, they remain significant contributors to N₂O emissions due to intensive industry and agriculture. Meanwhile, developing economies with energy intensity have structural impediments to emission mitigation. The paper also identifies the contribution of regulatory quality in emission abatement in that the quality of governance is found to be linked with better environmental performance. ESG-based finance instruments, such as green bonds and impact investing, also promote sustainable economic transition. The findings have the further implications of additional arguments for mainstreaming sustainability in economic planning, developing ESG frameworks to underpin climate targets. Full article

The agricultural sector is the largest source for air pollutants of ammonia (NH₃) and greenhouse gases (GHGs) of nitrous oxide (N₂O) and methane (CH₄). Establishing a unified and homologous emission inventory of air pollutants and GHGs is essential for synergistic abatement pathway studies of air pollution and climate change. However, current agriculture emission inventories of air pollutants and GHGs are unclear due to the separated source classification and inconsistent calculating methodologies. This study adopted a synergistic approach to develop a unified emission inventory for NH₃, N₂O, and CH₄ from the agricultural sector in China for 2021, based on crop and livestock types as the activity level data, and considered regional-specific species in emission factors. The results showed that China’s agricultural emissions in 2021 amounted to 7566.17 Gg of NH₃, 486.14 Gg of N₂O, and 14,979.71 Gg of CH₄. Rice, cattle, and pigs were the primary contributors of NH₃, N₂O, and CH₄. Hotspots of NH₃ and N₂O emissions were concentrated in the North China Plain and Sichuan Basin, whereas CH₄ emissions were predominantly located in southern China. This study provides a crop- and livestock-specific data foundation for making region-specific and priority-based integrated strategies to improve air quality, mitigate climate change, and promote sustainable agricultural development in China. Full article

Cataracts, the leading cause of blindness globally, are caused by oxidative stress and inflammation, which disrupt lens transparency due to increased accumulation of reactive oxygen species (ROS) as well as protein and DNA damage during aging. Using in vitro, ex vivo, and in vivo models, we determined the protective efficacy of N-acetylcysteine amide (NACA) against oxidative stress-induced and aging-induced cataractogenesis. We found that lens epithelial cells exposed to the oxidative stress inducers hydrogen peroxide (H₂O₂) or tert-butyl hydroperoxide showed significant ROS accumulation and reduced cellular viability. These effects were inhibited by NACA via the suppression of ROS and thioredoxin-interacting protein (Txnip) expression, a regulator of oxidative stress-related cellular damage and inflammation. In ex vivo lens experiments, NACA significantly reduced H₂O₂-induced lens opacity and preserved lens integrity. Similarly to NACA-treated lenses ex vivo, the integrity and opacity of aged mouse lenses, when topically instilled with NACA, were preserved and reduced, respectively, and are directly related to reduced Txnip and increased thioredoxin (Trx) expression levels. Overall, our findings demonstrated the protective ability of NACA to abate aberrant redox-active pathways, particularly the ROS/TRX/TXNIP axis, thereby preventing cataractogenesis and preserving eye lens integrity and ultimately impeding aging-related cataracts. Full article

Metallic Pd/Ni gauzes, located downstream of the Pt/Rh ammonia oxidation catalyst nets in the Ostwald process, is the current technology for capturing volatile gas phase platinum and rhodium species lost from the Pt/Rh combustion catalyst through evaporation. In this screening study, we explore four oxide families, ABO₃ perovskites, (ABO₃)_n(AO) Ruddlesden–Popper (RP) phases, AO rock salt, and A₂O₃ sesquioxide type oxides, as alternative materials for platinum capture. It was found that all the tested nickelates, LaNiO₃, NdNiO₃, La₂NiO₄, and La₄Ni₃O₁₀, captured platinum well and formed A₂NiPtO₆. In contrast, La_0.85Sr_0.15FeO₃, LaFeO₃, and LaCoO₃ did not capture platinum. CaO, SrO, and Nd₂O₃ formed low-dimensional platinates such as Ca_xPt₃O₄, Sr₄PtO₆, and a newly discovered neodymium platinate, Nd_10.67Pt₄O₂₄. Gd₂O₃ did not capture platinum in bench-scale experiments in dry air, but did, however, seem to capture platinum under pilot plant conditions, likely due to the co-capture of Co lost from the N₂O abatement catalyst. The catalytic activity of both oxides and platinum-containing products were studied, toward NO_x and N₂O decomposition. None of the oxides showed significant activity toward NO_x decomposition, and all showed activity toward N₂O decomposition, but to different extents. An overall assessment of the screened oxides with respect to potential use in industrial Ostwald conditions is provided. All tested oxides except CaO and SrO withstood industrial conditions. From our assessments, the nickelates and A₂O₃ (A = Nd, Gd) stand out as superior oxides for platinum capture. Full article

Pharmaceutical industry effluents often contain high concentrations of refractory organic solvents, chemical oxygen demand (COD), and total dissolved solids (TDSs). These wastewaters, including N-containing organic solvents known for their persistence and toxicity, pose significant environmental challenges. The study evaluated the efficacy of 3D/Granular Activated Carbon (GAC)/O₃ treatment compared to linear process additions when treating real pharmaceutical wastewater, and revealed a 2.73-fold enhancement in COD mineralization. The process primarily involves the direct oxidation of monoprotic organic acids found in real pharmaceutical effluents, such as acetic and formic acid, crucially influencing mineralization rates. Optimal conditions determined via the response surface methodology were 125 g/L GAC, 30 mA/cm², and 75 mg/L O₃, achieving high total organic carbon (TOC) and COD removal efficiencies of 87.19 ± 0.19% and 89.67 ± 0.32%, respectively (R² > 0.9), during verification runs. Current density emerged as the key parameter for organic abatement, aligning with the emphasis on direct oxidation at the anode surface. This integrated approach enhances biodegradability (BOD₅/COD) and reduces acute toxicity associated with persistent N-containing solvents, demonstrating promising applications in pharmaceutical wastewater treatment. Full article

Relative to soluble N sources, enhanced-efficiency fertilizers (EEFs) support steady turfgrass growth and dense canopy quality while abating N loss as nitrate, ammonia, and/or N₂O from turfgrass systems. Modern EEFs provide turfgrass managers greater operational effect and versatility in their nutrient management efforts and compel field characterization of their temporal response. Likewise, field confirmation of commercial EEF nutrient recovery helps stakeholders select the appropriate EEF for their specific application. Our research objective was to quantify the temporal response of Kentucky bluegrass growth/yield, canopy density and color, and fertilizer N recovery to a practical application of conventional urea or an enhanced-efficiency granular fertilizer. In May 2014 and June 2018, Kentucky bluegrass plots were fertilized by granules of conventional urea, N-(n-butyl) thiophosphoric triamide (NBPT)-, and dicyandiamide (DCD)-stabilized urea, or polymer-/sulfur-coated urea (PSCU) at a N rate of 43.9 kg ha⁻¹ (0.9 lbs/1000 sq. ft.). The dependent variable response over the two growing seasons was highly affected by efficiency enhancement. Following the repeated 16.5-week evaluations, the mean percent of fertilizer N recovered from conventional urea, stabilized urea, and PSCU totaled 57.5, 68.4, and 89.1%, respectively. In the 23 to 51 days from treatment (DFT), recovery of PSCU-N significantly exceeded that from conventional or stabilized urea. Full article

The development of advanced photocatalysts for air pollution removal is essential to improve indoor air quality. TiO₂/mesoporous silica SBA-15 nanocomposites were synthesized using an organometallic decoration method, which leverages the high reactivity of Ti precursors to be hydrolyzed on the surface water groups of silica supports. Both lab-made Ti(III) amidinate and commercial Ti(IV) amino precursors were utilized to react with water-rich SBA-15, obtained through a hydration process. The hydrated SBA-15 and the TiO₂/SBA-15 nanocomposites were characterized using TGA, FTIR, ¹H and ²⁹Si NMR, TEM, SEM, N₂ physisorption, XRD, and WAXS. This one-step TiO₂ decoration method achieved a loading of up to 51.5 wt.% of approximately 9 nm anatase particles on the SBA-15 surface. This structuring provided excellent accessibility of TiO₂ particles for photocatalytic applications under pollutant gas and UV-A light exposure. The combination with the high specific surface area of SBA-15 resulted in the efficient degradation of 400 ppb of NO pollutant gas. Due to synergistic effects, the best nanocomposite in this study demonstrated a NO abatement performance of 4.0% per used mg of TiO₂, which is 40% more efficient than the reference photocatalytic material TiO₂ P-25. Full article

In this research, long-term monitoring data from 2020 to 2023 were used to characterize O₃ pollution in a typical inland city in northwest China (34°21′ N 109°30′ E), which indicated that ozone pollution yielded typical regular fluctuations and high ozone concentrations from April to September were observed. Ozone varied in the range of 16–176 μg/m³, and maximum peaks were found usually at 14:00–17:00 in June and July. Correlation analysis showed a significant positive relationship between ozone and temperature, with correlation coefficients of 0.93. The wind speed exhibits a similar variation as ozone. Meanwhile, negative correlations were not so notably observed among ozone, humidity, VOCs, and NOx. Finally, the empirical kinetic model OZIPR (Ozone Isopleth Plotting Program for Research) was employed to analyze the sensitivity relationship among ozone and precursor compounds by calculating EMKA (Empirical Kinetics Modeling Approach) curves. The EKMA analysis results showed that during the whole ozone pollution period, ozone formation is mainly dominated by VOCs due to all the ratios of VOCs/NOx which fell in the VOCs control region. Therefore, VOCs should be priority controlled and more measures should be taken for better ozone pollution control abatement. Full article

In the present work, the photodegradation performances of N-doped TiO₂ photocatalysts with enhanced absorption of visible light were exploited for the abatement of some representative contaminants of emerging concern (CECs). Pristine TiO₂ and N-TiO₂ were synthesized using hydrothermal (HT) and sol–gel (SG) routes, they were characterized using XRD and UV-Vis spectroscopy, and their band gaps were determined via analysis in diffuse reflectance. Their photodegradation efficiency was tested on a mixture of recalcitrant organic pollutants, namely, benzotriazole, diclofenac, sulfamethoxazole, and bisphenol A, using a solar simulator lamp with two different cut-off filters (λ > 340 nm and λ > 400 nm). The evaluation of the photocatalytic performances was initially carried out in spiked ultrapure water and subsequently in aqueous matrices of increasing complexity such as Po River water and water coming from an aquaculture plant. The exclusive utilization of visible light (λ > 400 nm) highlighted the advantage of introducing the dopant into the TiO₂ photocatalyst since this modification allows for the material to be responsive to visible light, which is not sufficient in the case of pristine TiO₂ and the higher efficiency of materials obtained via the sol–gel route. Thanks to the doping, improved performance was obtained in both ultrapure water and real water matrices, indicating the potential of the doped material for future applications in the field. Full article

Photocatalytic NO removal is usually accompanied by the generation of NO₂, an intermediate with a higher toxicity than NO. Therefore, it is critically important to develop new photocatalysts capable of NO selective conversion. Herein, we report on the synergistic roles of cyano and hydroxyl functional groups in photocatalytic NO removal. According to the results, the NO₂ production efficiencies on cyano/hydroxyl-group-modified g-C₃N₄ (DCN-O-R) was limited to 4.8%, which was lower than that of cyano-group-modified g-C₃N₄ (DCN, 38.6%) and pure g-C₃N₄ (CN, 50.0%). Meanwhile, the photocatalytic NO conversion efficiency over DCN-O-R was higher than that of DCN and g-C₃N₄. It was found that the insertion of cyano groups favorably changes the energy band of g-C₃N₄ towards the generation of •O₂⁻. NO can only be oxidized to NO₂ by the photogenerated holes. When NO₂ is adsorbed on the surface of hydroxyl groups, it can be further oxidized to the product NO₃⁻ by •O₂⁻. The synergistic effect of bifunctional groups regulates the conversion pathway from NO→NO₂ to NO→NO₂→NO₃⁻. This work provides a strategy to abate toxic intermediates during the NO removal process, underlining the importance of surface/interface molecular engineering in regulating catalytic reaction pathways. Full article

The reduction of $\mathrm{C}{\mathrm{O}}_2$ emissions in hard-to-abate industries is described in several proposals on the European and National levels. In order to meet the defined goals, the utilization of sustainable, non-fossil fuels for process heat generation in industrial furnaces needs to be intensified. The focus mainly lies on hydrogen (${\mathrm{H}}_2$) and its derivates. Furthermore, biofuels, e.g., dimethyl ether (DME), are considered. Besides possible changes in the process itself when substituting natural gas (NG) with alternative fuels, the emission of nitrogen oxides ($\mathrm{N}{\mathrm{O}}_{\mathrm{x}}$) is a major topic of interest. In current European standards and regulations, the $\mathrm{N}{\mathrm{O}}_{\mathrm{x}}$ emissions are specified in mg per m³ of dry off-gas and refer to a reference oxygen concentration. Within this study, this limit specification is investigated for its suitability for the use of various fuel-oxidizer combinations in industrial combustion applications. Natural gas is used as a reference, while hydrogen and DME are considered sustainable alternatives. Air and pure oxygen (${\mathrm{O}}_2$) are considered oxidizers. It is shown that the current specification, which is built on the use of fossil fuels, leads to non-comparable values for alternative fuels. Therefore, alternative $\mathrm{N}{\mathrm{O}}_{\mathrm{x}}$ limit definitions are discussed in detail. The most suitable alternative was found to be mg per kWh. This limit specification is finally being investigated for its compliance with current regulations on various aspects of Continuous Emission Monitoring Systems. Full article