MOLECULES
·
2023
·Vol. 28
·期 8
·3511
·
IF 4.6
Xingfan Gong,Jiacheng Xu,Tiantian Zhang,Yan Sun,Shiyu Fang,Ning Li,Jiali Zhu,Zuliang Wu,Jing Li,Erhao Gao,Wei Wang,Shuiliang Yao
Cu-doped manganese oxide (Cu–Mn2O4) prepared using aerosol decomposition was used as a CO oxidation catalyst. Cu was successfully doped into Mn2O4due to their nitrate precursors having closed thermal decomposition properties, which ensured the atomic ratio of Cu/(Cu + Mn) in Cu–Mn2O4close to that in their nitrate precursors. The 0.5Cu–Mn2O4catalyst of 0.48 Cu/(Cu + Mn) atomic ratio had the best CO oxidation performance, withT50andT90as low as 48 and 69 °C, respectively. The 0.5Cu–Mn2O4catalyst 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–Mn2O4were reactive at a low temperature, resulting in-good low-temperature CO oxidation performance. Water could adsorb on 0.5Cu–Mn2O4and inhibited M=O and M-O-M reaction with CO. Water could not inhibit O2decomposition to M=O and M-O-M. The 0.5Cu–Mn2O4catalyst had excellent water resistance at 150 °C, at which the influence of water (up to 5%) on CO oxidation could be completely eliminated.Keywords:doping;Cu–Mn2O4;CO oxidation;oxygen vacancy;water resistance;DRIFTS-MS
研究领域:
催化化学
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材料科学
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环境科学
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产品关联
DOI
PubMed
高影响因子
Communications Chemistry
·
2022
·Vol. 5
·期 1
·1-8
·
IF 7.211
Xu Jiacheng,Zhang Tiantian,Fang Shiyu,Li Jing,Wu Zuliang,Wang Wei,Zhu Jiali,Gao Erhao,Yao Shuiliang
Understanding of the roles of oxygen species at reducible metal oxide surfaces under real oxidation conditions is important to improve the performance of these catalysts. The present study addresses this issue by applying a combination of operando diffuse reflectance infrared Fourier transform spectroscopy with a temperature-programmed reaction cell and mass spectrometry to explore the behaviors of oxygen species during H 2 oxidation in a temperature range of 25–400 °C at β-MnO 2 surfaces. It is revealed that O 2 is dissociated simultaneously into terminal-type oxygen (M 2+ -O 2– ) and bridge-type oxygen (M + -O 2– -M + ) via adsorption at the Mn cation with an oxygen vacancy. O 2 adsorption is inhibited if the Mn cation is covered with terminal-adsorbed species (O, OH, or H 2 O). In a temperature range of 110–150 °C, OH at Mn cation becomes reactive and its reaction product (H 2 O) can desorb from the Mn cation, resulting in the formation of bare Mn cation for O 2 adsorption and dissociation. At a temperature above 150 °C, OH is reactive enough to leave bare Mn cation for O 2 adsorption and dissociation. These results suggest that bare metal cations with oxygen vacancies are important to improve the performance of reducible metal oxide catalysts.
研究领域:
催化化学
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材料科学
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表面科学
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DOI
高影响因子
Molecular Catalysis
·
2022
·
IF 5.089
Jiacheng Xu,Tiantian Zhang,Shiyu Fang,Zuliang Wu,Erhao Gao,Jiali Zhu,Shuiliang Yao,Jing Li,Lianxin Dai,Weihua Liu,Buhe Zhang,Junwei Zhang
The position of the catalyst in a plasma reactor has an important effect on performance of plasma driven catalytic reaction. An operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and mass spectrometry (MS) has been used to investigate CO oxidation on MnO 2 catalyst in in-plasma catalysis (IPC) and post-plasma catalysis (PPC) configurations. It was found that the catalyst in IPC configuration has higher CO conversion and CO 2 selectivity than that in PPC configuration. Operando DRIFTS-MS analysis showed that the IPC configuration generated more reactive oxygen species (M O) on the catalyst surface than the PPC configuration, where M O, M 2+ -O 2 2– , and M + O 2 – are important reactive species promoting CO oxidation to monodentate carbonate that is easy to gasify to gaseous CO 2 . The physical adsorbed O 3 on the catalyst in PPC configuration converts to M 2+ -O 2 2– which combines with CO to form bidentate carbonates that is difficult to gasify to gaseous CO 2 . The mechanisms of CO oxidation on the catalyst in IPC and PPC configurations are discussed.
研究领域:
化学工程
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催化科学
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产品关联
DOI
高影响因子
Molecular Catalysis
·
2023
·
IF 4.6
Tiantian Zhang,Jiacheng Xu,Yan Sun,Shiyu Fang,Zuliang Wu,Erhao Gao,Jiali Zhu,Wei Wang,Lianxin Dai,Weihua Liu,Buhe Zhang,Junwei Zhang,Shuiliang Yao,Jing Li
Nano-Au has a good catalytic activity for CO oxidation, but its catalytic mechanism is still not clear. Here, CO oxidation on Au 2 O 3 and its thermal decomposition products were studied using thermogravimetric-mass spectrometry (TG-MS) and operando diffuse reflectance infrared Fourier transform spectroscopy-mass spectrometry (DRIFTS-MS) to explore the key active components of Au catalyst for CO oxidation. The TG-MS results showed that Au 2 O 3 decomposed to AuO at 210 °C and Au at 375 °C and was oxidized to form Au oxide above 375 °C. When Au 2 O 3 decomposed into Au x O y (x>y) above 210 °C, the CO oxidation activity obviously increased. Au atoms in the Au-Au system serve as electron donor and CO adsorption sites. Au atom is oxidized to AuO by the O atom from O 2 decomposition following the Epling-Xu decomposition mechanism. A schematic diagram of the key components of Au 2 O 3 catalysts during CO oxidation was proposed based on TG-MS and operando DRIFTS-MS analysis results.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
ChemCatChem
·
2023
·Vol. 15
·期 7
·e202300194
·
IF 4.5
Tao Li,Mengling Dong,Jiacheng Xu,Tiantian Zhang,Yan Sun,Ning Li,Zuliang Wu,Jing Li,Erhao Gao,Jiali Zhu,Shuiliang Yao,Yong Huang
Graphical CeO 2 /γ-Al 2 O 3 , Pd/CeO 2 , and Pd/CeO 2 /γ-Al 2 O 3 were used for catalyzing low-concentration CH 4 oxidation . γ-Al 2 O 3 can efficiently promote CH 4 oxidation on Pd/CeO 2 and the formation of bicarbonate that is easily gasified to CO 2 . CeO 2 /γ-Al 2 O 3 , Pd/CeO 2 , and Pd/CeO 2 /γ-Al 2 O 3 were used for catalyzing low-concentration CH 4 oxidation. It was found that nano-sized Pd could obviously promote CH 4 oxidation on CeO 2 /γ-Al 2 O 3 . The interaction between Pd and CeO 2 on γ-Al 2 O 3 resulted in higher ratios of Ce 3+ /(Ce 3+ +Ce 4+ ), Pd 2+ /(Pd 2+ +Pd δ+ ), and O ads /(O ads +O latt ), those benefited the formation of more oxygen vacancies and surface reactive oxygen species for CH 4 oxidation. γ-Al 2 O 3 not only supplied a high surface area and enhanced Pd/CeO 2 dispersion on γ-Al 2 O 3 , but also simulated the formation of bicarbonate, where bicarbonate is easier to gasify to CO 2 than bidentate carbonate that formed on Pd/CeO 2 . Operando diffuse reflectance infrared Fourier transform spectroscopy-mass spectrometer analysis results showed that CH 4 oxidation could occur at a temperature as low as 180 °C due to the reaction with surface reactive OH, this reaction was also accompanied by the formation of bicarbonate. The mechanism of CH 4 oxidation promoted by bicarbonate formation on γ-Al 2 O 3 was proposed.
研究领域:
催化化学
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环境科学
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产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2024
·
IF 3.5
Zihao Hu,Xiaoying Zhou,Tiantian Zhang,Zuliang Wu,Jing Li,Wei Wang,Erhao Gao,Jiali Zhu,Shuiliang Yao
Aiming at the problem of the poor performance of an Mn-MOF-74-derived Mn3O4 catalyst in low-temperature carbon monoxide (CO) oxidation, copper (Cu) and cerium (Ce) elements were used to modify the Mn3O4 catalyst to improve its performance in low-temperature CO oxidation. According to the results of catalytic performance testing, the CO oxidation activity of the Cu0.3Mn2.7O4 catalyst was significantly improved compared with that of the pristine Mn3O4 catalyst, when a CO conversion rate of 90% was achieved at 118 °C. According to X-ray photoelectron spectroscopy and Brunauer–Emmett–Teller analyses, the (Mn2+ + Mn3+)/(Mn2+ + Mn3+ + Mn4+) ratio and the Oads/Ototal ratio increased after Cu doping, indicating promoted oxygen vacancy generation. In addition, the increased specific surface area was beneficial for the adsorption of reactant molecules and the exposure of active sites. According to H2-temperature-programmed reduction characterization, Cu doping significantly enhanced the performance of the Cu0.3Mn2.7O4 catalyst during low-temperature redox. Finally, these factors synergistically promoted the degradation of CO over the Cu0.3Mn2.7O4 catalyst. In addition, operando diffuse reflectance Fourier transform infrared spectroscopy results suggested the presence of more terminal-type oxygen, which is essential for the catalytic oxidation of CO on the surface of the Cu0.3Mn2.7O4 catalyst. Moreover, the Cu0.3Mn2.7O4 catalyst also showed excellent resistance to carbonate, and remarkable stability.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Jiacheng Xu,Shun Wang,Chenyun Zhang,Jing Zhang,Lihua Xu,Yue Shi,Guoqiang Xu,Shuiliang Yao
Catalyst surface active oxygen species have an important influence on plasma catalytic oxidation . However, the reaction process of CO and O 3 migration and transformation on the catalyst surface during discharge at different temperature is still unclear. In this study, β- and γ -MnO 2 are selected to unveil the roles of different oxygen species under in-plasma catalysis configuration at different temperature in CO oxidation. Operando TPR-DRIFTS-MS is used to reveal CO and O 3 oxidation pathways. The results show that O 3 can react with CO at room temperature, and O 3 is also converted to other reactive oxygen species on the catalyst surface. As the temperature increases, the oxygen species of the catalyst itself (Mn O and Mn-O-Mn) can react with CO to form oxygen vacancies (Mn-□-Mn and Mn=□). Mn-□-Mn are beneficial for O 2 decomposition and promotes the regeneration of Mn O and Mn-O-Mn. The carbonate covered on the surface of the catalyst is the rate-determining step of CO oxidation. It is hoped that Mn-based catalysts with more reactive oxygen species and oxygen defects will be prepared to facilitate low-temperature CO oxidation under plasma conditions.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2023
·
IF 5.5
Jiacheng Xu,Tiantian Zhang,Yan Sun,Shiyu Fang,Zuliang Wu,Jiali Zhu,Lianxin Dai,Weihua Liu,Buhe Zhang,Junwei Zhang,Shuiliang Yao,Erhao Gao,Jing Li
MnO 2 is a promising catalyst due to its abundant metal valence and good redox ability. Different crystal phases of MnO 2 have different oxygen species, but the relationship between their catalytic activity and crystal structures is unclear. In this study, four MnO 2 catalysts with crystal structures ( α -, β -, γ -, and δ -MnO 2 ) were selected to unveil the roles of terminal-type (Mn O), superoxide-type Mn(-O-) 2 Mn, and bridge-type (Mn-O-Mn) oxygen species in CO oxidation . γ -MnO 2 has the best CO oxidation performance. Density functional theory calculation results show that Mn O on γ- MnO 2 can adsorb CO easier than other two types of oxygen species. Operando TPR-DRIFTS-MS results show that Mn O on the surface of γ- MnO 2 can react with CO to form terminal-type oxygen vacancies (M 2+ =□ 2– ) at low temperatures. Meanwhiles, Mn(-□-)(-O-)Mn and Mn-□-Mn can dissociate O 2 to form Mn O under certain conditions to promote CO oxidation. MnO 2 catalysts with more Mn O oxygen species are of great significance for CO oxidation at a low temperature.
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DOI
高影响因子
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