FUEL
·
2024
·
IF 6.7
Wei Fu,Muhammad Kashif,Chen Cai,Jiayin Chen,Hao Zhou,Bingtao Zhao,Philippe M. Heynderickx,Yaxin Su
The hydrothermal technique was applied to prepare a new metal–organic framework, MIL-100(Fe), which was modified by ultrasonic impregnation with different wt % of copper. The results showed that the NO x conversion over 2.3Cu-MIL-100(Fe) was 100 % at 275 °C and maintained at ≥ 85 %, with N 2 selectivity ≥ 90 % in the temperature range of 275–400 °C and high SO 2 resistance. An increase in the Cu content up to 2.3 wt% showed the highest surface area (1206 m 2 /g) observed in N 2 adsorption–desorption. The results show that the introduction of Cu increased the oxygen vacancies on the catalyst surface. Electron transfer and a synergistic effect were observed between Cu and Fe. The shift of the reduction peaks to lower temperatures after the addition of Cu confirmed that Cu improved the reducibility of the catalysts. The 2.3Cu-MIL-100(Fe) exhibited the highest Lewis content (44.97 μmol/g), which functions as an active site for the selective catalytic reduction (SCR) reaction. By precisely controlling the acid-base properties of the catalyst, the specificity for the desired products can be increased in complicated reaction systems, especially in hydrocarbon-SCR technology.
研究领域:
材料科学
·
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2019
·
IF 7.65
Hong Sun,Zhigang Liu,Ying Wang,Xie Quan,Guozhi Zhao
A novel MnOx@MIL-125(Ti) catalyst was constructed for the selective catalytic reduction (SCR) of NOx with NH 3 , in which MIL-125(Ti), a kind of metal-organic frameworks (MOFs), was used as the support because of the structural feature, large surface area and high thermal stability. The SCR results showed that MnOx@MIL-125(Ti) exhibited high deNOx ability and N 2 selectivity in a wide operating temperature range. Moreover, it exhibited better SO 2 resistance than MnOx/TiO 2 (P25). Characterization results revealed that MIL-125(Ti) had resulted in a high dispersion of MnOx and a strong metal-support interaction for MnOx@MIL-125(Ti), which could promote the formation of the abundant Mn 4+ and surface chemical oxygen, facilitating the activation of the reactants. In situ DRIFTS results suggested that NH 3 -SCR over MnOx@MIL-125(Ti) followed both Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanism. In addition, NO − species were proved to be the important intermediates which were involved in SCR reaction.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2023
·
IF 7.4
Fengyuan Liu,Junqi Li,Hong Yong Sohn,Chaoyi Chen,Jian Yang,Xudong Liu,Yuanpei Lan,Wei Zhang,Qin Wang,Li Liu
The objective of this work was to clearly elucidate the interactions on Mn-Ce interface and understand how they affect low temperature selective catalytic reduction (SCR) for NO x removal. In this work, three Mn-Ce catalysts in similar particle size and morphology with different Mn-Ce interface areas were prepared. MnO 2 @CeO 2 -F had the tightest and largest amount of Mn-Ce interfaces compared with MnO 2 @CeO 2 -P and MnO 2 -CeO 2 -M, and also exhibited the highest NO conversion degree at 100–150 °C as well as the strongest activity of Mn species and lowest generation of N 2 O. The TG-DTG, XPS and electrochemical impedance spectroscopy results proved the redox of Ce 4+ + Mn 3+ ↔ Ce 3+ + Mn 4+ on the Mn-Ce interface, and MnO 2 @CeO 2 -F had the highest Mn 4+ , Ce 3+ , O α concentrations. The results of the study on the redox reactions during the NH 3 -SCR process provided powerful evidence of the Mn 4+ /Mn 3+ and Ce 3+ /Ce 4+ recycles that are important for low temperature NH 3 -SCR process. Moreover, the Mn-Ce interface was directly proved to benefit the surface acid sites, redox ability, and activity of the adsorbed intermediates. Both the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) reaction mechanisms were observed in the SCR reaction with prepared Mn-Ce materials, where “fast SCR” can be observed with MnO 2 @CeO 2 -F. Moreover, the Mn-Ce interface also lowers the activation energy of the low-temperature SCR process, with MnO 2 @CeO 2 -F having the lowest activation energy. The results from this work offered powerful evidences for the interactions of Mn/Ce redox at the Mn-Ce interface and elucidated clear understanding of the effects of Mn-Ce redox on low-temperature SCR process, which is expected to promote the NO x removal process.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
MOLECULES
·
2022
·Vol. 27
·期 15
·4863
·
IF 4.927
Shun Li,Zuquan Zheng,Zhicheng Zhao,Youling Wang,Yao Yao,Yong Liu,Jianming Zhang,Zuotai Zhang
CeO2nanoparticle-loaded MnO2nanoflowers, prepared by a hydrothermal method followed by an adsorption-calcination technique, were utilized for selective catalytic reduction (SCR) of NOxwith NH3at low temperatures. The effects of Ce/Mn ratio and thermal calcination temperature on the NH3–SCR activity of the CeO2-MnO2nanocomposites were studied comprehensively. The as-prepared CeO2-MnO2catalysts show high NOxreduction efficiency in the temperature range of 150–300 °C, with a complete NOxconversion at 200 °C for the optimal sample. The excellent NH3–SCR performance could be ascribed to high surface area, intimate contact, and strong synergistic interaction between CeO2nanoparticles and MnO2nanoflowers of the well-designed composite catalyst. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) characterizations evidence that the SCR reaction on the surface of the CeO2-MnO2nanocomposites mainly follows the Langmuir–Hinshelwood (L-H) mechanism. Our work provides useful guidance for the development of composite oxide-based low temperature NH3–SCR catalysts.Keywords:Mn-Ce mixed oxide;ion-adsorption;selective catalytic reduction;NOxconversion
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Zhi Liu,Minmin Wang,Shoujie Liu,Zheng Chen,Lingzhi Yang,Kaian Sun,Yanju Chen,Lingyou Zeng,Wenhong Wang,Jinchong Zhao,Guangxun Sun,Bin Liu,Yuan Pan,Yunqi Liu,Chenguang Liu
The biggest challenge for selective catalytic reduction (SCR) of NO by NH 3 at low temperatures is to develop robust catalysts with high resistance to SO 2 . Mn-based catalysts have attracted great attention for their excellent activity, but the poor SO 2 resistance limits their application. Herein, we report a novel assembled composite featuring Mn 3 O 4 nanoparticles embedded in defect-abundant graphitic carbon frame (Mn 3 O 4 @G-A) via a confinement–pyrolysis–oxidation strategy derived from MOF. The Mn 3 O 4 @G-A exhibits excellent activity (reaching over 90 % NO conversion in 100, 000 h −1 GHSV at 160 °C) and significantly improved SO 2 resistance in comparison to pristine Mn 3 O 4 , and all the performance tests were conducted with 5.6 vol.% water vapor. By combining synchrotron radiation-based X-ray absorption spectroscopy and density functional theory calculation, we further discovered the positive role and the origin of graphitic carbon for improving SO 2 resistance. Over the Mn 3 O 4 @G-A sample, the electrons can be transferred from graphitic carbon to Mn 3 O 4 nanoparticles, which can regulate the electronic properties and oxidizing ability of Mn 3 O 4 nanoparticles. The proper oxidizing ability of Mn 3 O 4 @G-A can inhibit the oxidation of SO 2 to SO 3 , thus further avoid the formation of NH 4 HSO 4 and improve the SO 2 resistance. Our work here not only solves the current problem of poor SO 2 resistance of Mn-based catalysts, but also provides new insights into the design and synthesis of MOF-derived graphitic carbon-containing catalysts for SCR applications.
研究领域:
催化化学
·
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2022
·Vol. 29
·期 47
·71721-71730
·
IF 5.19
Huang Wenjun,Li Sichao,Wang Hongbin,Cui Peng,Xu Haomiao,Cheng Can,Qu Zan,Yan Naiqiang
Oxidation–reduction-absorption based on sulfite is a promising process for simultaneous removal of NO x and SO 2 . However, excessive oxidation of sulfite and competitive absorption between NO x and SO 2 limit its application. A matching strategy between antioxidants and alkaline agents has been proposed to solve these problems and enhance the absorption process. The comparison results of inhibitors showed that hydroquinone exhibited long-term high-efficiency inhibition of S(IV) (SO 3 2- /HSO 3 - ) oxidation. The comparison of alkaline agents showed that the Na 2 SO 3 solution with heterogeneous mixture of MgO and hydroquinone exhibited better absorption performance than that with other combinations. The absorption amounts of NO x in 0.15 mol/L Na 2 SO 3 50 mL solution added 0.1% hydroquinone (HQ) with 0.09 mol/L MgO were 2.24 mmol, which improved 5 times than that without additives. In addition, studies on the influence of pH showed that the pH of MgO mixture could be stabilized at 9–10 for a long time, while the pH of Na 2 CO 3 mixture decreased faster. Further studies suggested that the hydration of MgO resulted in the solution with MgO keeping high pH. This is also the main reason why the combination of MgO and hydroquinone is superior to the combination of Na 2 CO 3 and hydroquinone in desulfurization and denitration performance.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2025
·
IF 9.7
Minghu Zhao,Junyi Chen,Fei Wu,Yungang Wang,Kai Chen,Chao Xiong,Rongshu Zhu
Rationally designing catalysts suitable for flue gas purification at low temperatures and unraveling the anti-poisoning mechanism at the atomic level remain challenges. Here, a highly dispersed Ni-doped MnO x catalyst (Ni 0.1 Mn 0.9 O x ) was constructed and applied for selective catalytic reduction (SCR) of nitrogen oxides (NO x ). The long-term stability of Ni 0.1 Mn 0.9 O x is up to 80% (180 ℃) after 18 h under SO 2 and H 2 O conditions. This is due to the fact that the highly dispersed Ni atoms enhance the redox and surface acidity of MnO x , and modulate the electronic structure of the active Mn sites. The denitrification reaction on Ni 0.1 Mn 0.9 O x mainly follows the Eley-Rideal mechanism. The anti-poisoning mechanism is that the introduction of Ni weakens the electron transfer between the Mn site and SO 2 , thereby inhibiting the adsorption of SO 2 . In particular, the H 2 O adsorbed on the Ni sites is decomposed to replenish the depleted Brønsted acid sites, which facilitates the adsorption of NH 3 . However, an excess of H 2 O can have an inhibitory effect. In addition, the mesoporous structure may increase the mass transfer rate and reduce the accumulation of harmful substances. This study provides viable insights for the design of SCR catalysts with excellent anti-poisoning ability.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Kaiqi Wang,Bo Lin,Wende Xiao
A coprecipitation approach was used to prepare vanadium–molybdenum composite oxide catalysts, which were then calcined at 300, 400, 500, 600, and 700 °C. The vanadium–molybdenum catalyst, under calcination at 500 °C, possesses abundant surface defects and acid species. As a result, it showed an outstanding active window, achieving over 90% NOx conversion efficiency within the temperature range of 220–340 °C. Compared with other catalysts, the vanadium–molybdenum catalyst with the calcination at 500 °C resulted in the formation of polymeric vanadate with the most active oxygen, which was conducive to the high catalytic efficiency for the NH3-SCR reaction. Based on our in-depth understanding gained from in situ DRIFTS experiments, we proposed that the NH3-SCR reaction occurred on the vanadium–molybdenum catalyst via an Eley–Rideal pathway. This mechanism involves the initial adsorption of ammonia on the catalytic surface, followed by its interaction with weakly adsorbed or gaseous NO to form an activated complex. Furthermore, the presence of molecular oxygen (O2) serves to augment the adsorption and activation of nitric oxide over the catalytic surface. The augmentation arises from the generation of adsorbed NO2 species or nitrates, which possess pronounced oxidizing capabilities. Notably, the significant impact of NH3 and NO in the denitration reaction was elucidated, providing valuable insights that can guide the adjustment and optimization of practical operational conditions. This understanding is crucial for enhancing the efficiency and effectiveness of the denitration process, thereby contributing to improved environmental qualities.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2021
·
IF 8.271
Dongyue Zhao,Yuexi Yang,Zhongnan Gao,Mengxin Yin,Ye Tian,Jing Zhang,Zheng Jiang,Xiaobo Yu,Xingang Li
Herein, we report the excellent De-NO x performance of La 0.7 Sr 0.3 MnO 3 (LSM) perovskite-supported Pd catalysts (Pd-LSM) in alternating lean-burn/fuel-rich atmospheres using C 3 H 6 as reductant and describe the in situ activation of the Pd catalysts via metal-support interaction (MSI) tuning. The NO x reduction conversion of the Pd-LSM catalyst increased significantly from 56.1% to 90.1% and the production of N 2 O was suppressed. Our results demonstrated that this behavior was mainly attributed to the in situ transformation of Pd 2+ into Pd 0 during the reaction. The generated Pd 0 species could readily activate the C 3 H 6 reductant and achieve an eight-fold higher turnover frequency than Pd 2+ for the reduction of NO x . Moreover, excessive MSIs inhibited the in situ generation of Pd 0 , and thereby, lowered the De-NO x activity of the catalyst even at high Pd dispersion. In addition, the Pd-LSM catalysts exhibited much higher S tolerance than conventional Al 2 O 3 -supported catalysts. Our study provides a new approach for analyzing and designing highly active metal catalysts operated under dynamic alternating oxidizing/reducing atmospheric conditions.
研究领域:
催化化学
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Xin Yong,Hong Chen,Huawang Zhao,Miao Wei,Yingnan Zhao,Yongdan Li
The effects of SO 2 on an one-pot synthesized Cu-SSZ-13 catalyst for selective reduction of NO x by NH 3 were examined. The addition of SO 2 inhibited NO x conversion significantly below 300 °C, while no effect on NO x conversion was observed above 300 °C. TGA, TPD , and XPS results showed that the deactivation was caused by the formation of (NH 4 ) 2 SO 4 , SO 2 chemisorption on the isolated Cu 2+ ion sites, as well as the formation of CuSO 4 -like species. Among them, the site-blocking effect of (NH 4 ) 2 SO 4 on Cu 2+ was the primary reason for deactivation. Fortunately, 89% of deNO x activity of the poisoned catalyst was recovered after thermal treatment at 500 °C in air, where (NH 4 ) 2 SO 4 was completely decomposed. The activity was further recovered with regeneration temperature increasing to 600 °C, removing the adsorbed SO 2 on the Cu 2+ sites. The regeneration at 600 °C could not recover the activity completely, because of the high stability of CuSO 4 -like species.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Xianghui Li,Yingnan Zhao,Huawang Zhao,Mengke Liu,Yuhan Ma,Xin Yong,Hong Chen,Yongdan Li
Two kinds of Cu-SAPO-34 catalysts, prepared with a one-pot technique using Cu- tetraethylenepentamine as co-template and an ion-exchange method, were hydrothermally treated at 750 °C for at least 16 h. The migration of Cu species during hydrothermal treatment and the corresponding effect on the selective catalytic reduction (SCR) of NO x were examined and characterized. A certain amount of CuO exists outside and inner the crystallites in the as prepared ion-exchanged sample, whereas copper is mainly atomically dispersed in the one-pot sample existing as isolated Cu 2+ . After hydrothermal treatment for 16 h, the amount of the inner nanosized CuO in the ion-exchanged sample reduced and the copper disperses to form more isolated Cu 2+ . However, surface CuO particles increase at the sacrifice of isolated Cu 2+ with extending the hydrothermal treatment to 24 h. Aggregation of Cu 2+ species also happens during the aging treatment over the one-pot prepared sample where the initial Cu is atomically dispersed as isolated Cu 2+ . The increase of the amount of the isolated Cu 2+ enhances the low-temperature (< 350 °C) performance. However, the increase of the amount of surface CuO particles in the aged samples promotes the nonselective NH 3 oxidation reaction in the high temperature range and results in the lowering of the SCR activity by limiting NH 3 supply.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2020
·
IF 5.778
Jiuhu Zhao,Gaige Zhang,Jiansheng He,Zhengzhong Wen,Zhi Li,Tingkun Gu,Ran Ding,Yongji Zhu,Rongshu Zhu
In/H-Beta catalyst was prepared by optimizing the support, concentration of ion exchange liquid and calcination temperature to investigate the effects of synthesis conditions on catalytic activity of selective catalytic reduction of NO x with CH 4 . The results showed that the In/H-Beta catalyst exhibited the superior activity when concentration of exchange liquid was 0.033 M and calcination temperature was 500 °C, the NO x removal ratio could reach 97.6%. In addition, reaction conditions could affect the catalytic performance. When O 2 concentration was 10%, CH 4 :NO ratio was no less than one, space velocity was lower than 23600 h −1 and NO initial concentration was no more than 700 ppm, In/H-Beta could exhibit superior catalytic activity. Moreover, the catalytic performances of In/H-Beta catalysts were discussed after enduring H 2 O or/and SO 2 . This novel strategy could open the door for selective catalytic reduction of NO x with CH 4 .
研究领域:
环境科学
·
催化化学
✓ 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）