Synergistic oxidation of toluene through bimetal/cordierite monolithic catalysts with ozone

Scientific Reports, Journal Year: 2024, Volume and Issue: 14(1)

Published: March 26, 2024

Abstract Toluene treatment has received extensive attention, and ozone synergistic catalytic oxidation was thought to be a potential method degrade VOCs (violate organic compounds) due its low reaction temperature high efficiency. A series of bimetal/Cord monolithic catalysts were prepared by impregnation with cordierite, including Mn x Cu 5−x /Cord, Co /Cord (x = 1, 2, 3, 4). Analysis textural properties, structures morphology characteristics on the conducted evaluate their performance toluene conversion. Effects active component ratio, addition space velocity investigated. Results showed that best among three bimetal catalysts, conversion mineralization rates reached 100 96% under condition 2 3 3.0 g/m O at 12,000 h −1 . Ozone in could efficiently avoid 40% reduction specific surface area because it lower optimal from 300 °C. (Co/Mn)(Co/Mn) 4 diffraction peaks XRD spectra indicated all four 1−x had spinel structure, peak intensity largest ratio Mn:Co 2:3. rate increased rising concentration intermediate products generated degradation might react excess generate free radicals like ·OH, which would improve catalyst. This study provide theoretical support for industrial application.

Language: Английский

---

Modelling molecular composition of SOA from toluene photo-oxidation at urban and street scales

Environmental Science Atmospheres, Journal Year: 2024, Volume and Issue: 4(8), P. 839 - 847

Published: Jan. 1, 2024

Near-explicit chemical mechanisms representing toluene SOA formation are reduced using the GENOA algorithm and used in 3D simulations of air quality over Greater Paris streets a district near Paris.

Language: Английский

---

Weakened Gas-to-Particle Partitioning of Oxygenated Organic Molecules in Liquified Aerosol Particles

Environmental Science & Technology Letters, Journal Year: 2022, Volume and Issue: 9(10), P. 837 - 843

Published: Sept. 21, 2022

Aqueous-phase chemistry plays an important role in secondary organic aerosol (SOA) formation. However, the mechanism of interaction between physics and is still poorly understood. Here continuous measurements gas- particle-phase composition organics were conducted using iodine-adduct time-of-flight chemical ionization mass spectrometer coupled with a filter inlet for gases aerosols Beijing to understand physicochemical processes related SOA Our results showed that contributed 65.9% OA 17.1% nonrefractory PM2.5 during whole campaign. These values are lower than those reported previous studies. oligomerization from methylglyoxal (C3H4O2) oligomers (C4–7H6–10O5) probable path direct gas-to-particle partitioning some CxHyOz particle-gas partition coefficient ≳1.0 × 10–5 weakened when water content (AWC) exceeds 15 μg m–3, corresponding relative glass transition temperature below 0.85 compared AWC <15 m–3. A phase solid/semisolid liquid, increasing diffusivity particles, should explain observed inhibition and, subsequently, low fraction at high humidity pollution events. This study provides new insights into formation mechanism.

Language: Английский

---

Formation, radiative forcing, and climatic effects of severe regional haze

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(7), P. 4951 - 4967

Published: April 14, 2022

Abstract. Severe regional haze events, which are characterized by exceedingly high levels of fine particulate matter (PM), occur frequently in many developing countries (such as China and India), with profound implications for human health, weather, climate. The occurrence the extremes involves a complex interplay between primary emissions, secondary formation, conducive meteorological conditions, relative contributions various processes remain unclear. Here we investigated severe episodes 2013 over Northern Plain (NCP), evaluating PM production interactions elevated planetary boundary layer (PBL). Analysis ground-based measurements satellite observations properties shows nearly synchronized temporal variations among three megacities (Beijing, Baoding, Shijiazhuang) this region coincidence aerosol optical depth (AOD) hotspots during polluted period. During clean-to-hazy transition, measured oxygenated organic concentration ([OOA]) well correlates odd-oxygen ([Ox]=[O3]+[NO2]), mean [OOA] / [Ox] ratio Beijing is much larger than those other Mexico City Houston), indicating highly efficient photochemical activity. Simulations using Weather Research Forecasting (WRF) model coupled an explicit radiative module reveal that strong aerosol–PBL interaction period results suppressed stabilized PBL humidity, triggering positive feedback to amplify severity at ground level. Model sensitivity study illustrates importance black carbon (BC) haze–PBL climatic effect, contributing more 30 % collapse about half forcing on top atmosphere. Overall, exhibits negative (cooling) −63 −88 W m−2 surface (warming) 57 82 atmosphere, slightly net −6 Our work establishes synthetic view dominant features unraveling rapid situ inefficient transport, both amplified atmospheric stagnation. On hand, transport sufficiently disperses gaseous precursors (e.g., sulfur dioxide, nitrogen oxides, volatile compounds, ammonia) clean period, subsequently result via photochemistry transition multiphase chemistry findings highlight co-benefits reduction BC not only improve local air quality minimizing stagnation but also mitigate global warming alleviating direct forcing.

Language: Английский

---

An overlooked oxidation mechanism of toluene: computational predictions and experimental validations

Chemical Science, Journal Year: 2023, Volume and Issue: 14(45), P. 13050 - 13059

Published: Jan. 1, 2023

Secondary organic aerosols (SOAs) influence the Earth's climate and threaten human health. Aromatic hydrocarbons (AHs) are major precursors for SOA formation in urban atmosphere. However, revealed oxidation mechanism dramatically underestimates contribution of AHs to formation, strongly suggesting importance seeking additional pathways formation. Using toluene, most abundant AHs, as a model system combination quantum chemical method field observations based on advanced mass spectrometry, we herein demonstrate that second-generation can form novel epoxides (TEPOX) with high yield. Such TEPOX further react H2SO4 or HNO3 aerosol phase less-volatile compounds including non-aromatic ring-retaining organosulfates organonitrates through reactive uptakes, providing new candidates AH-derived future ambient observation. With newly mechanism, chemistry-aerosol box modeling yield toluene reach up 0.35, much higher than 0.088 original under conditions pH = 2 0.1 ppbv NO. This study opens route uptake from significantly fills current knowledge gap

Language: Английский

---