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
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2025
·
IF 8.3
Deng Zhao,Fei Wang,Qingxin Li,Wenming Han,Huashan Wang,Hua Liu,Suning Li,Hui Liu,Shuai Guo,Yonghong Yan
It is well known that AAEMs (alkali and alkaline earth metals) and TMs (transition metals) have different catalytic mechanisms for the cellulose pyrolysis. There is potential for synergy among different metals during the pyrolysis. This study mainly used in-situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) to comprehensively study the catalytic mechanism of different metals (Na, Ca, Fe, Co, and Ni) during cellulose pyrolysis. The mechanism of synergistic interaction between different metals was explained according to the catalytic characteristics of different metals. The results showed that different metals had different effects on the activation pathway. Na and Ca retained a part of O in the char, thereby inhibiting the graphitization process, while Fe, Co, and Ni tended to interact directly with the carbon structure to enhance its stability. When binary metals co-catalyzed, Na and Ca showed a competitive mechanism for combining with O, while the cooperation of Na and Fe accelerated the depolymerization of cellulose. In this study, the proposed improved in-situ diffuse reflection infrared reaction chamber with more accurate temperature control could become a solid foundation for studying the catalytic properties of different single in the pyrolysis of cellulose.
研究领域:
能源科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Deng Zhao,Yu Wang,Guanwei Wang,Wenming Han,Hua Liu,Huashan Wang,Hui Liu,Shuai Guo
Although alkali metal potassium (K)-catalyzed char gasification has been widely studied, the detailed mechanism of this process is still not fully understood. To study this catalytic mechanism in more detail, high-temperature in-situ DRIFTS experiments were carried out for the gasification of cellulose char with K and cellulose char without K under H 2 O and O 2 atmospheres, transient gasification experiment of char with K under H 2 O atmosphere, and char with K gasification under isotope water atmospheres. Peaks at 1945 cm −1 and 2020 cm −1 were observed. Combined with the theoretical spectra obtained by quantum chemical simulations and the prediction of catalytic gasification intermediates by molecular dynamics simulations, these two peaks were confirmed to represent char-polyynes species. Based on this result, a new mechanism is proposed: K interacts with carboxyl groups and aromatic ketones to promote desorption, thereby exposing active sites. Then, K reacts with the edge of the activated char to form numerous highly active char-polyynes species. The polyynes edge of this char-polyynes phase provides ideal adsorption–desorption sites, enabling further reaction with the gasifier. Thus, gas desorption is promoted. The adsorption and desorption peaks of catalytic gasification under the H 2 O atmosphere were located at 1400 cm −1 and 1300 cm −1 , and these peaks represented stable adsorption states and unstable desorption precursors, respectively. Based on this, adsorption–desorption theory was analyzed more comprehensively, and the adsorption–desorption process was divided into three stages: initial adsorption, intermediate conversion, and desorption. The comprehensive new mechanism proposed in this paper provides a better understanding of the nature of char catalytic gasification at a deeper level.
研究领域:
化学工程
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2018
·
IF 4.521
Li Cao,Lei Chen,Xiaodong Wu,Rui Ran,Tengfei Xu,Ze Chen,Duan Weng
The CeO 2 /TiO 2 catalyst was prepared by a deposition-precipitation method, which exhibited high low-temperature activity under the fast SCR condition. By using transient reaction analysis (TRA), the steps in the fast SCR, including NO 2 adsorption and decomposition, reaction between nitrates and NO, ammonium nitrate formation and reduction by NO, were investigated. Diffuses reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments, via NO + O 2 or NO + NO 2 adsorption, ammonium species reaction with NO x and NO reaction with NH 4 NO 3 , were designed to identify the roles of NO, NO 2 and NH 3 in fast SCR. Based on L-H mechanism, the NH 4 NO 3 formation played an important role in low-temperature SCR reaction. Compared with the behavior in standard SCR, the higher activity in the presence of NO 2 was ascribed to the faster NH 4 NO 3 formation rate and larger amounts of nitrates/nitrites. This phenomenon provided a basis for developing Ce-based catalysts as SCR catalysts for diesel exhaust aftertreatment.
研究领域:
催化化学
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环境科学
✓ 已验证
产品关联
DOI
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
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 4
·1245-1256
·
IF 6.177
Jie Yang,Shan Ren,Mingming Wang,Zhichao Chen,Lin Chen,Lian Liu
Ce–Ti catalysts were considered as a promising replacement for V–Ti based catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with NH3. In this work, a CeO2/TiO2 catalyst was prepared by the impregnation method and studied by a series of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. The results showed that CeO2 particles grew along TiO2 faces and amorphous cerium in the lattice of TiO2, both of which are present on the CeO2/TiO2 catalyst. NH4+ might adsorb on the Ti–O–Ce structures or TiO2–CeO2 interface as Brønsted acid sites, while two types of NH4+ species were distinguished by the time-resolved spectroscopic method due to the different increasing trends. Based on the temporal evolution transient in situ DRIFTS spectra, L-NH3 had higher activity than coordinated NH3 species, which suggested that gas phase NO reacted preferentially with L-NH3. The NH4NO3 intermediate dominated the SCR reactions over the CeO2/TiO2 catalyst, which followed the Eley–Rideal mechanism.
研究领域:
催化化学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Leipeng Ji,Zhisong Liu,Zihao Li,Wenjun Huang,Haomiao Xu,Zan Qu,Naiqiang Yan
The gypsum from flue gas desulfurization or the neutralization (D/N gypsum) process of acid wastewater, is an industrial by-product in nonferrous metal smelters. The S and Ca sources of D/N gypsum have significant application prospects. However, the S(IV) reduction is difficult due to the electronic inactivity of CaSO 4 and the stability of the S-O band. Our experimental results indicated that the start-up temperature of CaSO 4 reduced by CH 4 is 900 ℃. However, adding H 2 S gas with a H 2 S/CaSO 4 (S/Ca) ratio of 0.2, the start-up temperature of CaSO 4 reacted with CH 4 decreases to 650 ℃. With the increase of the S/Ca ratio from 0.04 to 0.2, the yield of CaS increased to 94.97%, and the selectivity toward CO 2 formation increases to 71.67%. In-situ diffuse reflectance Fourier transformations spectroscopy (in-situ DRIFTs) results indicate that adding H 2 S generates the new sulfide groups on the surface of CaSO 4 , resulted from the S(-II) in H 2 S changing the distribution of valence electrons of O and activating O. Moreover, the density functional theory (DFT) calculation results exhibit that the activation energy for the first O dissociation decreases to 2.89 eV in the presence of H 2 S. Furthermore, H 2 S optimized the reaction path of CH 4 and improved the selectivity toward CO 2 formation. Comparing to 1000 ℃ without H 2 S, under 800 ℃ with H 2 S, the consumption of CH 4 reduces to 45%, and the CO 2 selectivity increases to 71.67%. Thus, we have developed a method of CaSO 4 low-temperature reduction and provide a theoretical basis for its application in engineering.
研究领域:
化学工程
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材料科学
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环境科学
✓ 已验证
产品关联
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
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Zhen-Yu Zhang,Tao Xie
Solar-driven photo-thermal dry reforming of methane (DRM) is an environmentally friendly production route for high-value-added chemicals. However, the lack of thorough understanding of the mechanism for photo-thermal reaction has limited its further development. Here, we systematically investigated the mechanism of photo-thermal DRM reaction with the representative of Ru/CeO 2 catalyst. Through in situ DRIFTs and transient experiments, comprehensive investigation into the reaction steps and their reactive sites in the process of DRM reaction were conducted. Besides, the excitation and migration direction of photo-electron was determined by ISI-XPS experiments, and the change of surface defect structure induced by light was characterized by ISI-EPR experiments. Based on the above results, the photo-enhancement effect on each micro-reaction step was determined. This study provides a theoretical basis for the industrialization of photo-thermal DRM reaction and its development of catalysts.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2024
·
IF 4.8
Jie Fan,Lutao Mao,Mingli Fu,Peng Liu,Zuliang Wu,Daiqi Ye
The high efficiency and stability of catalysts are crucial for their practical application in toluene oxidation . Herein, a novel octahedral Pt/Mn 3 O 4 -110 catalyst with excellent structural stability was synthesized and 100 % toluene conversion can be achieved at low-temperature 160 °C. XRD and Raman results indicated that the structure of Pt/Mn 3 O 4 -110 can be well maintained after 120 h on-stream reaction, the resistance to H 2 O (3 or 5 vol%) and high concentration toluene (3000 ppm)/CO 2 (5 vol%) tests. In situ DRIFTS comparative studies between Pt/Mn 3 O 4 -110 and Pt/Mn 3 O 4 -100 (30 % toluene conversion at 160 °C) samples demonstrated that the rate-control steps of toluene oxidation on Pt/Mn 3 O 4 -110 and Pt/Mn 3 O 4 -100 were both the further oxidation of benzoate species in the presence of gas-phase oxygen, while the transformation of benzaldehyde to benzoate species was the rate-control step on Pt/Mn 3 O 4 -100 in the absence of gas-phase oxygen. The weaker Mn-O bonds, richer oxygen vacancies and higher mobility of oxygen species on Pt/Mn 3 O 4 -110 sample than that of Pt/Mn 3 O 4 -100 are beneficial for the easier release of lattice oxygen from the surface of catalyst and then participated in toluene oxidation via Mars-van Krevelen mechanism, contributing to easier oxidation of benzaldehyde to benzoate species and formation of formic acid and bicarbonate species.
研究领域:
催化化学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Jinping Zhong,Yikui Zeng,Mingyuan Zhang,Weihua Feng,Diran Xiao,Junliang Wu,Peirong Chen,Mingli Fu,Daiqi Ye
Improving catalytic efficiency is a yet still challenge in thermal catalytic oxidation. One of the key issues is to understand its catalytic oxidation mechanism. Here, a series of Co 3 O 4 samples were prepared by solvothermal method. The characterization records showed that nanotubular Co 3 O 4 -NTs-2 for its rough surface, low temperature reducibility, abundance of Co 3+ ions and surface adsorption oxygen species, thus exhibited high efficiency (T 90 = 240℃, Ea = 67.42 kJ/mol) in catalytic oxidation of toluene. In-situ DRIFTS combined PTR-TOF-MS were applied to investigate the reaction process of toluene oxidation. These results revealed that the catalytic oxidation of toluene followed the listed way: toluene → benzyl alcohol → benzaldehyde → benzoate → benzene → phenol → benzoquinone → maleic anhydride and other ring opening by-products like ethanol, acetaldehyde, acetic acid, acetone etc., then ultimately mineralized to CO 2 and H 2 O. Furthermore, the results of quasi in-situ XPS in C 7 H 8 /N 2 , toluene conversion in O 2 -free evaluation and UV–vis-DRS analysis further confirmed that surface lattice oxygen played an important role in toluene oxidation, and gas-phase oxygen facilitated the reaction. The combination of a series of instruments provided a promising means for further understanding the oxidation mechanism of toluene.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Catalysts
·
2021
·Vol. 11
·期 3
·324
·
IF 4.146
Jinkun Guan,Lusha Zhou,Weiquan Li,Die Hu,Jie Wen,Bichun Huang
SO2poisoning is a great challenge for the practical application of Mn-based catalysts in low-temperature selective catalytic reduction (SCR) reactions of NOxwith NH3. A series of Gadolinium (Gd)-modified MnOx/ZSM-5 catalysts were synthesized via a citric acid–ethanol dispersion method and evaluated by low-temperature NH3-SCR. Among them, the GdMn/Z-0.3 catalyst with the molar ratio of Gd/Mn of 0.3 presented the highest catalytic activity, in which a 100% NO conversion could be obtained in the temperature range of 120–240 °C. Furthermore, GdMn/Z-0.3 exhibited good SO2resistance compared with Mn/Z in the presence of 100 ppm SO2. The results of Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction of H2(H2-TPR) and temperature-programmed desorption of NH3(NH3-TPD) illustrated that such catalytic performance was mainly caused by large surface area, abundant Mn4+and surface chemisorbed oxygen species, strong reducibility and the suitable acidity of the catalyst. The in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) results revealed that the addition of Gd greatly inhibited the reaction between the SO2and MnOxactive sites to form bulk manganese sulfate, thus contributing to high SO2resistance. Moreover, in situ DRIFTS experiments also shed light on the mechanism of low-temperature SCR reactions over Mn/Z and GdMn/Z-0.3, which both followed the Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanism.Keywords:SO2poisoning;low temperature;NH3-SCR;in situ DRIFTS
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
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