Dataset Information

DRIFTS-MS Investigation of Low-Temperature CO Oxidation on Cu-Doped Manganese Oxide Prepared Using Nitrate Aerosol Decomposition.

ABSTRACT: Cu-doped manganese oxide (Cu-Mn₂O₄) prepared using aerosol decomposition was used as a CO oxidation catalyst. Cu was successfully doped into Mn₂O₄ due to their nitrate precursors having closed thermal decomposition properties, which ensured the atomic ratio of Cu/(Cu + Mn) in Cu-Mn₂O₄ close to that in their nitrate precursors. The 0.5Cu-Mn₂O₄ catalyst of 0.48 Cu/(Cu + Mn) atomic ratio had the best CO oxidation performance, with T₅₀ and T₉₀ as low as 48 and 69 °C, respectively. The 0.5Cu-Mn₂O₄ catalyst also had (1) a hollow sphere morphology, where the sphere wall was composed of a large number of nanospheres (about 10 nm), (2) the largest specific surface area and defects on the interfacing of the nanospheres, and (3) the highest Mn³⁺, Cu⁺, and Oads ratios, which facilitated oxygen vacancy formation, CO adsorption, and CO oxidation, respectively, yielding a synergetic effect on CO oxidation. DRIFTS-MS analysis results showed that terminal-type oxygen (M=O) and bridge-type oxygen (M-O-M) on 0.5Cu-Mn₂O₄ were reactive at a low temperature, resulting in-good low-temperature CO oxidation performance. Water could adsorb on 0.5Cu-Mn₂O₄ and inhibited M=O and M-O-M reaction with CO. Water could not inhibit O₂ decomposition to M=O and M-O-M. The 0.5Cu-Mn₂O₄ catalyst had excellent water resistance at 150 °C, at which the influence of water (up to 5%) on CO oxidation could be completely eliminated.

SUBMITTER: Gong X

PROVIDER: S-EPMC10144047 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature

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Publications

DRIFTS-MS Investigation of Low-Temperature CO Oxidation on Cu-Doped Manganese Oxide Prepared Using Nitrate Aerosol Decomposition.

Gong Xingfan X Xu Jiacheng J Zhang Tiantian T Sun Yan Y Fang Shiyu S Li Ning N Zhu Jiali J Wu Zuliang Z Li Jing J Gao Erhao E Wang Wei W Yao Shuiliang S

Molecules (Basel, Switzerland) 20230416 8

Cu-doped manganese oxide (Cu-Mn2O4) prepared using aerosol decomposition was used as a CO oxidation catalyst. Cu was successfully doped into Mn2O4 due to their nitrate precursors having closed thermal decomposition properties, which ensured the atomic ratio of Cu/(Cu + Mn) in Cu-Mn2O4 close to that in their nitrate precursors. The 0.5Cu-Mn2O4 catalyst of 0.48 Cu/(Cu + Mn) atomic ratio had the best CO oxidatio ...[more]

PMID: 37110744

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Project description:The nitrate radical (NO3) oxidation of isoprene is an important contributor to secondary organic aerosol (SOA). Isoprene has two double bonds which allow for multigeneration oxidation to occur. The effects of multigeneration chemistry on the gas- and particle-phase product distributions of the isoprene + NO3 system are not fully understood. In this study, we conduct chamber experiments by varying the ratio of N2O5 (precursor of NO3) to isoprene concentration from 1:1 to 14:1 to investigate the formation of products in both phases under different oxidation levels. Multigeneration chemistry leads to the formation of gas-phase products which then partition into particle phase depending on the product volatility; first-generation products (15-36% of total SOA) such as C5H9NO5 and C10H16N2O9 have volatility (log10C* = 1.0-3.0 using the partitioning method and log10C* = 2.6-4.5 using the formula method) 1-5 orders of magnitude higher than second-generation products (37-57% of total SOA, log10C* = -0.8-2.1 using the partitioning method and log10C* = -3.7-1.8 using the formula method) such as C5H8,10N2O8, C5H9N3O10, and C10H17N3O13. The fast reaction rate constants of first-generation products (estimated to be on the order of 10-13 cm3 molecules-1 s-1 at 295 K) and the lower volatility of second-generation products result in increased SOA yields when NO3 availability increases and multigeneration chemistry is enhanced. Specifically, an increase of up to 300% in SOA yield is observed when the N2O5/isoprene ratio increases from 1:1 to 3:1; from 5.7% (organic aerosol mass concentration, ΔM o = 4.2 μg/m3) to 16.3% (ΔM o = 11.9 μg/m3) when the reacted isoprene concentration is 25 ppb and from 3.1% (ΔM o = 1.2 μg/m3) to 12.4% (ΔM o = 5.4 μg/m3) when the reacted isoprene concentration is 15 ppb. The maximum SOA yield occurs when the N2O5/isoprene ratio is greater than or equal to 3:1 as a combined result of multigeneration chemistry and peroxy radicals (RO2) fate. We encourage future studies to consider both factors, which can vary under different laboratory and ambient conditions, when comparing SOA yields to better understand any differences observed. Our results highlight that multigeneration chemistry and the updated parameters including reaction rate constants and volatility distribution of products should be considered to enable a more comprehensive representation and prediction of SOA formation from NO3 oxidation of isoprene in atmospheric models.

Dataset Information

DRIFTS-MS Investigation of Low-Temperature CO Oxidation on Cu-Doped Manganese Oxide Prepared Using Nitrate Aerosol Decomposition.

Publications

DRIFTS-MS Investigation of Low-Temperature CO Oxidation on Cu-Doped Manganese Oxide Prepared Using Nitrate Aerosol Decomposition.

Similar Datasets

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