Molecular Insights into NO-Promoted Sulfate Formation on Model TiO 2 Nanoparticles with Different Exposed Facets

Self Cite

Industrialization has resulted in the rapid increase of volatile organic compound (VOC) emissions, which have caused serious issues to human health and the environment. In this study, an extensive Cu incorporating TiO 2 induced nucleophilic oxygen structure was constructed in the CuTiO x catalyst, which exhibited superior low-temperature catalytic activity for C 3 H 6 combustion. Thorough structural, surface characterization and density functional theory (DFT) calculations revealed that the Cu−O−Ti hybridization induced nucleophilic oxygen initiates C 3 H 6 combustion by abstracting the C−H bond. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results indicated that incorporated copper species acted as the major adsorbent site for the propene molecule. In combination of the DRIFTS and DFT results, the promotion effect of the nucleophilic O on the C−H bond abstraction and CO 2 formation pathway was proposed. The surface doping induced nucleophilic oxygen as strong Brønsted basic sites for low-temperature propene combustion exemplified an efficient strategy for rational design of next-generation environmental catalysts.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Engineering the Nucleophilic Active Oxygen Species in CuTiO_x for Efficient Low-Temperature Propene Combustion

Fang

Yang

et al. 2020

Self Cite

“…Recently, synergistic effects between NO x and SO 2 have been found in field campaigns, laboratory experiments, and model simulations. − Both coexisting NO 2 − and NO were found to improve the conversion of SO 2 to sulfate on mineral dust due to the oxidizability of NO 2 . On the other hand, SO 2 was also demonstrated to change the reaction pathways of NO 2 in these heterogeneous reactions on mineral dust.…”

Section: Introductionmentioning

confidence: 99%

Efficient Conversion of NO to NO₂ on SO₂-Aged MgO under Atmospheric Conditions

Liu

Wang

et al. 2020

Self Cite

The NO–NO2 cycle determines the formation of O3 and hence plays a critical role in the oxidizing capacity of troposphere. Traditional view concluded that the heterogeneous oxidation of NO to NO2 was negligible due to the weak reactivity of NO on aerosols, compared to the homogeneous oxidation process. However, the results here reported for the first time that SO2 can greatly promote the heterogeneous transformation of NO into NO2 and HONO on MgO particles under ambient conditions. The uptake coefficients of NO were increased by 2–3 orders of magnitudes on SO2-aged MgO, compared to the fresh sample. Based on spectroscopic characterization and density functional theory (DFT) calculations, the active sites for the adsorption and oxidation of NO were determined to be sulfates, where an intermediate [SO4–NO] complex was formed during the adsorption. The decomposition of this species led to the formation of NO2 and the change of sulfate configuration. The formed NO2 could further react with surface sulfite to form HONO and sulfate. The conversion of NO to NO2 and HONO on the SO2-aged MgO surface under ambient conditions contributes a new formation pathway of NO2 and HONO and could be quite helpful for understanding the source of atmospheric oxidizing capacity as well as the formation of air pollution complexes in polluted regions such as the northern China.

“…Recent studies have investigated SO 2 uptake on mineral dust proxy particles and authentic mineral dust particles as well as the effects of nitrate, H 2 O 2 , NH 3 , NO, acetaldehyde, RH, and mineral dust structure (SI Table S4). For example, nitrate was found to enhance the uptake of SO 2 on the surface of hematite via in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and a White cell coupled with Fourier transform infrared spectroscopy (white cell-FTIR) and ATD particles using flow tube experiments .…”

Section: Laboratory Studies Of Reaction Pathways Of Current Interestmentioning

confidence: 99%

“…Kong et al suggested that the enhancement is due to the formation of HONO that further oxidizes SO 2 to sulfate while Zhang et al attributed the enhancement to the formation of HNO 3 that accelerates the radical-chain reaction of SO 2 oxidation. H 2 O 2 , NH 3 , and NO were also found to enhance the SO 2 uptake on mineral dust particles.…”

Section: Laboratory Studies Of Reaction Pathways Of Current Interestmentioning

confidence: 99%

Multiphase Oxidation of Sulfur Dioxide in Aerosol Particles: Implications for Sulfate Formation in Polluted Environments

Liu

Chan

Abbatt

2021

127

122

Atmospheric oxidation of sulfur dioxide (SO2) forms sulfate-containing aerosol particles that impact air quality, climate, and human and ecosystem health. It is well-known that in-cloud oxidation of SO2 frequently dominates over gas-phase oxidation on regional and global scales. Multiphase oxidation involving aerosol particles, fog, and cloud droplets has been generally thought to scale with liquid water content (LWC) so multiphase oxidation would be negligible for aerosol particles due to their low aerosol LWC. However, recent field evidence, particularly from East Asia, shows that fast sulfate formation prevails in cloud-free environments that are characterized by high aerosol loadings. By assuming that the kinetics of cloud water chemistry prevails for aerosol particles, most atmospheric models do not capture this phenomenon. Therefore, the field of aerosol SO2 multiphase chemistry has blossomed in the past decade, with many oxidation processes proposed to bridge the difference between modeled and observed sulfate mass loadings. This review summarizes recent advances in the fundamental understanding of the aerosol multiphase oxidation of SO2, with a focus on environmental conditions that affect the oxidation rate, experimental challenges, mechanisms and kinetics results for individual reaction pathways, and future research directions. Compared to dilute cloud water conditions, this paper highlights the differences that arise at the molecular level with the extremely high solute strengths present in aerosol particles.