Catalysts
·
2021
·Vol. 11
·期 3
·324
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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
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环境科学
✓ 已验证
产品关联
DOI
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
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
Catalysis Science & Technology
·
2021
·Vol. 11
·期 15
·5125-5134
·
IF 6.119
Yanke Yu,Xianfang Yi,Jiali Zhang,Zhaojian Tong,Changwei Chen,Mudi Ma,Chi He,Jinxiu Wang,Jinsheng Chen,Bingbing Chen
Non-vanadium-based catalysts with high SO2 tolerance are still interesting in selective catalytic reduction of NO by NH3 (NH3-SCR) and SO2 adsorption is the foremost step for the deactivation of catalysts. In order to alleviate the adsorption of SO2, we fabricated a series of rhenium (Re; without stable sulfate) supported TiO2 catalysts and studied their SO2 tolerance for the first time. Owing to suitable surface acidity and reducibility, ReOx/TiO2 catalysts exhibited satisfactory activity in a wide temperature range of 250–350 °C. As expected, experimental results and DFT calculations indicated that SO2 adsorption on ReOx/TiO2 catalysts was rather weak, thus the catalysts performed excellent SO2 tolerance in the NH3-SCR reaction. Moreover, in situ DRIFTS indicated that the NH3-SCR reaction on ReOx/TiO2 catalysts followed the Eley–Rideal mechanism and SO2 had little effect on the reaction mechanism. Our findings should provide new insights into the development of SCR catalysts with high SO2 tolerance.
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
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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
FUEL
·
2022
·
IF 8.035
Yihua Yue,Zhongliang Huang,Dongren Cai,Shafqat Ullah,Abdul-Rauf Ibrahim,Xin Yang,Jiale Huang,Guowu Zhan
Controlled fabrication of spatial positions of different active sites on catalyst structures is critical to exploring the reaction mechanisms for CO 2 hydrogenation. Herein, two isomorphous zeolitic imidazolate frameworks (ZIF-67 and ZIF-8) were used as sacrificial templates to synthesize multi-layered Co 3 O 4 /ZnO catalysts with tunable core-shell structures and well-controlled spatial positions. The multi-layered catalysts were then evaluated for the catalytic performance for CO 2 hydrogenation. A series of characterization techniques were applied to investigate the morphology and structure of the Co 3 O 4 /ZnO composites with different spatial locations. Due to the unique multi-layered structure, the distinct interfacial structures, and the synergistic effects, the resultant core-shell structured Co 3 O 4 /ZnO nanocatalysts exhibited significantly enhanced activity as compared to their monometallic counterparts (pure Co 3 O 4 and ZnO). In addition, the ZnO@Co 3 O 4 with Co 3 O 4 as shell showed significantly higher CO 2 conversion (25%) than that of Co 3 O 4 @ZnO with ZnO as shell (0.82%). Furthermore, in-situ Diffuse Reflection Fourier Transform Infrared Spectroscopy (DRIFTS) analysis suggested that formate (HCOO*) and methoxy (CH 3 O*) species were the crucial intermediates in the CO 2 hydrogenation over the Co 3 O 4 /ZnO composite nanocatalysts. However, pure ZnO could not activate the CO 2 ; consequently, the use of the Co 3 O 4 /ZnO nanocatalysts derived from multiple-layered ZIFs structures provides new insights into improving the catalytic efficiency of CO 2 hydrogenation.
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
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
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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
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催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials
·
2023
·Vol. 16
·期 11
·4010
·
IF 3.4
Su Zhang,Baoyu Huang,Zenghao Jiang,Junfan Qian,Jiawei Cao,Qiuxia Feng,Jianwei Zhang,Xiaogan Li
Au modified TiO2/In2O3hollow nanospheres were synthesized by the hydrolysis method using the carbon nanospheres as a sacrificial template. Compared to pure In2O3, pure TiO2, and TiO2/In2O3based sensors, the Au/TiO2/In2O3nanosphere-based chemiresistive-type sensor exhibited excellent sensing performances to formaldehyde at room temperature under ultraviolet light (UV-LED) activation. The response of the Au/TiO2/In2O3nanocomposite-based sensor to 1 ppm formaldehyde was about 5.6, which is higher than that of In2O3(1.6), TiO2(2.1), and TiO2/In2O3(3.8). The response time and recovery time of the Au/TiO2/In2O3nanocomposite sensor were 18 s and 42 s, respectively. The detectable formaldehyde concentration could go down as low as 60 ppb. In situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was used to analyze the chemical reactions on the surface of the sensor activated by UV light. The improvement in the sensing properties of the Au/TiO2/In2O3nanocomposites could be attributed to the nanoheterojunctions and electronic/chemical sensitization of the Au nanoparticles.Keywords:Au modified TiO2/In2O3hollow nanospheres;room temperature formaldehyde sensors;UV activation;in situ DRIFTS
研究领域:
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
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2020
·
IF 7.489
Yaoyu Zhang,Yuxing Wang,Yue Liu,Qingji Ying,Zhongbiao Wu
A sequence of CuCeO x -HZSM-5 composite catalysts at different Cu-Ce loading synthesized by the citric acid complex impregnation method were evaluated for the catalytic oxidation of acetonitrile. Among which, the 2CuCeO x -HZSM-5 sample exhibited the best degradation efficiency. In the temperature range of 225–350 °C, its activity and mineralization rate were approximately 100%, and the N 2 selectivity remained more than 93%. The characterization results revealed that all the samples showed an existence of isolated Cu 2+ species. And more Cu-Ce mixed oxides covered on HZSM-5 at an elevated Cu-Ce content, leading to the enhanced reducibility. In situ DRIFTS results showed that both oxidation and hydrolysis reaction routes proceeded during the degradation of acetonitrile over the composite catalysts. Their synergism was crucial to guarantee both high activity and N 2 selectivity. The highly dispersed CuO x species ensured the superior activity of the 2CuCeO x -HZSM-5 sample. And Cu 2+ exchanged HZSM-5 zeolite would be beneficial to N 2 selectivity owing to the improved internal SCR (Selective Catalytic Reduction) reaction to reduce NO x from oxidation routes. Additionally, the mineralization rate was lowered with the formation of carbonaceous products like CH 4 and CO for the catalysts at low Cu-Ce loading due to the lack of redox capacity.
研究领域:
催化
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环境科学
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Kejing Wang,Yongjun Liu,Zhiwen Li,Nan Cui,Lei Sun,Wei Huang
The valence states of Cu site are regarded as an important factor affecting the performance of syngas to higher alcohols (C 2+ OH). Regrettably, the role of Cu 0 and Cu + in CO hydrogenation to higher alcohols remains controversial due to the complexity of the reaction. In this study, Cu 0 and Cu 2 O powders are directly added as the precursors to adjust the ratios of Cu + /(Cu 0 +Cu + ) and Cu particle sizes in CuZnAl catalysts by a complete liquid-phase (CLP) technology. The CAT-Cu 0 catalyst with higher Cu 0 content shows the highest CO conversion (>15%) ascribing to the biggest S Cu , but is also accompanied by the highest CO 2 selectivity (>40%), while the CAT-Cu + catalysts with higher Cu + content displays relative better C 2+ OH selectivity (>60%) and stability due to a higher probability of CO insertion. In-situ DRIFTS experiments reveal that a synergy between larger Cu particle sizes (30～40 nm) and surface Cu + sites, in which larger Cu sizes enhances the probability of bridge CO adsorption, thereby favoring the C–O bond dissociation for CH x formation. Meanwhile, Cu + active sites provide a higher probability for CO/CHO insertion to form CH 3 CHO*/CH 2 CO* intermediates. This study further deepens our understanding of the critical controlling factors for highly selective synthesis of C 2+ OH from syngas over Cu-based catalysts.
研究领域:
化学工程
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催化
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 10
·2255
·
IF 4.2
Yan Cui,Zequan Zeng,Yaqin Hou,Shuang Ma,Wenzhong Shen,Zhanggen Huang
Noble metals have become a research hotspot for the oxidation of light alkanes due to their low ignition temperature and easy activation of C-H; however, sintering and a high price limit their industrial applications. The preparation of effective and low-noble-metal catalysts still presents profound challenges. Herein, we describe how a Ru@CoMn2O4spinel catalyst was synthesized via Ru in situ doping to promote the activity of propane oxidation. Ru@CoMn2O4exhibited much higher catalytic activity than CoMn2O4, achieving 90% propane conversion at 217 °C. H2-TPR, O2-TPD, and XPS were used to evaluate the catalyst adsorption/lattice oxygen activity and the adsorption and catalytic oxidation capacity of propane. It could be concluded that Ru promoted synergistic interactions between cobalt and manganese, leading to electron transfer from the highly electronegative Ru to Co2+and Mn3+. Compared with CoMn2O4, 0.1% Ru@CoMn2O4, with a higher quantity of lattice oxygen and oxygen mobility, possessed a stronger capability of reducibility, which was the main reason for the significant increase in the activity of Ru@CoMn2O4. In addition, intermediates of the reaction between adsorbed propane and lattice oxygen on the catalyst were monitored by in situ DRIFTS. This work highlights a new strategy for the design of a low-noble-metal catalyst for the efficient oxidation of propane.
研究领域:
催化
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化学工程
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）