APPLIED CATALYSIS A-GENERAL
·
2021
·
IF 5.706
Huansheng Tan,Shibo Ma,Xiaoyu Zhao,Yushi Li,Chen Zhao,Yujun Zhu
Bimetallic W a CeO x (a = 0.06, 0.12, 0.18, 0.24) catalysts were synthesized for selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). The influences of W on structure, activity and surface properties were investigated by XRF, XRD, Raman, TEM, N 2 adsorption-desorption, H 2 -TPR, O 2 /NH 3 /SO 2 -TPD, XPS, and in-situ DRIFTS. The characterization results show that the W/Ce ratio has a great effect on the NH 3 -SCR activity. The different catalytic activities of W a CeO x are mainly attributed to the acidity change, especially the increase of B-acid content plays a major role in enhancing low temperature activity. W 0.18 CeO x exhibits excellent low-temperature NH 3 -SCR activity, SO 2 /H 2 O resistance and N 2 selectivity with a broad activity window (190–490 °C) with 5%H 2 O. Moreover, good activity window (235–460 °C) can be maintained even the catalyst treated with 5% H 2 O at 800 °C for 12 h, showing especial hydrothermal stability. Thus, it can be summarized that W 0.18 CeO x is regarded as outstanding catalyst for low-temperature NH 3 -SCR of NO.
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
Surfaces and Interfaces
·
2024
·
IF 5.7
Chengzhi Wang,Zhenbang Tian,Weiqing Huang,Jingyuan Hu,Xing Xing
Owing to the different reaction properties and deactivation mechanisms caused by the structural discrepancy of monolithic catalysts, abundant scientific results of powder or granular NH 3 -SCR catalysts have still not sufficiently robustly applied in recent years. Furthermore, minimal research has been focused on monolithic catalysts. As a result, this work prepared monolithic Mn-Fe-Ce/Al 2 O 3 catalysts by active component impregnation (ACI-Mn-Fe-Ce/Al 2 O 3 ) and precursor impregnation methods (PI-Mn-Fe-Ce/Al 2 O 3 ) and investigates the long-term SO 2 and H 2 O resistance of the catalysts. Compared with the PI-Mn-Fe-Ce/Al 2 O 3 catalyst, the monolithic ACI-Mn-Fe-Ce/Al 2 O 3 catalyst showed better performance. The catalytic activity follows a bell-shaped curve with an optimal performance at a drug loading of 5 %. The ACI-Mn-Fe-Ce/Al 2 O 3 catalyst exhibits long-term resistance to SO 2 and H 2 O and can still convert more than 70 % NO x after 168 h of SO 2 and H 2 O resistance test. Characterization of the ACI-Mn-Fe-Ce/Al 2 O 3 catalysts before and after the reaction showed that the reducibility decreased after the reaction, and more Mn 4+ was transformed into Mn 2+ to weaken the catalytic activity. However, more Fe 2+ and Ce 3+ were generated during the reaction, increasing the number of oxygen vacancies, oxygen defects, and hydroxyl-like groups, all of which would contribute to a certain extent to counteract the passivation effect of SO 2 on the catalysts. In situ DRIFTs analysis shows that the formation of surface sulfates has a minimal effect on the adsorption of NO, but it does affect the adsorption of coordinated NH 3 on Lewis acid sites. This work elucidates the deactivation details of Mn-Fe-Ce/Al 2 O 3 catalysts from the perspective of physicochemical properties, which provides a reference for the development of better low-temperature SO 2 -resistance catalysts for industrial applications.
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
Shuohan Yu,Yiyang Lu,Yuan Cao,Jiaming Wang,Bowen Sun,Fei Gao,Changjin Tang,Lin Dong
Mn-based catalysts were believed to be promoting low temperature NH 3 -SCR catalysts for their satisfactory catalytic activity, whereas their poor SO 2 and H 2 O tolerance inhibited their applications. In this work, utilizing poor SO 2 tolerance of Mn oxides, composite catalytic systems containing Mn oxides as deSO x catalyst was designed and synthesized, which exhibited excellent low temperature NH 3 -SCR performance in the presence of SO 2 and H 2 O. The deSO x mechanism of Mn oxides was systematically investigated. In results, SO 2 was catalytic oxidized on the surface of Mn oxides. Oxidized sulfur species could flow away from Mn oxides surface through feed gas flow or form MnSO 4 . When NH 3 and H 2 O were introduced into the feed gas, the oxidized sulfur species were completely deposited as NH 4 HSO 4 instead of forming MnSO 4 . Thus, SO 2 was removed from feed gas entirely resulting in the superb low temperature NH 3 -SCR performances. This work provided a general strategy to enhance SO 2 and H 2 O tolerance of NH 3 -SCR catalysts at low temperature by removing SO 2 using NH 3 and H 2 O who existed in the exhaust gas from stationary sources.
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
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2025
·
IF 3.7
Dingding Liu,Yating Huang,Zhenguo Li,Guohua Jing,Yongdan Li,Huawang Zhao
The advancements in engine technology have led to a decrease in exhaust temperatures, hence enhancing the activity of Cu-SSZ-13 at low temperatures becomes crucial and challenging. This enhancement can be achieved using dual-phase metal oxide/Cu-SSZ-13 composite catalysts. In this work, we evaluated the comparative efficacy of Mn 3 O 4 and Mn 2 O 3 and discovered that Mn 3 O 4 exhibited a significantly superior enhancement in deNO x activity of Cu-SSZ-13 at low temperatures, achieving 95% NO x conversion at 200 °C. This is substantially higher than the conversions recorded by Mn 2 O 3 /Cu-SSZ-13 (78%) and Cu-SSZ-13 (40%). Kinetic and IR results demonstrate that Mn 3 O 4 /Cu-SSZ-13 and Mn 2 O 3 /Cu-SSZ-13 composite samples share a same low-temperature pathway, where bridged nitrates formed on the MnO x react with adsorbed on Brønsted acid sites in Cu-SSZ-13. In this reaction pathway, bridged nitrate formation is identified as the rate-determining step. The distinctive structure of Mn 3 O 4 triggers an increase in oxygen vacancies, creating a higher content of chemically adsorbed oxygen, compared to Mn 2 O 3 . Those adsorbed oxygen facilitates bridged nitrate formation. Consequently, due to the larger amount of bridged nitrate formed on Mn 3 O 4 compared to Mn 2 O 3 , the Mn 3 O 4 /Cu-SSZ-13 sample exhibits higher activity.
研究领域:
环境催化
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材料化学
·
大气污染控制
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化学工程
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表面科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2021
·
IF 7.92
Jiawei Ji,Meizan Jing,Xiuwen Wang,Wei Tan,Kai Guo,Lulu Li,Xin Wang,Wang Song,Lijun Cheng,Jingfang Sun,Weiyu Song,Changjin Tang,Jian Liu,Lin Dong
The occurrence of NH 3 -SCR (selective catalytic reduction of NO with NH 3 ) reaction on catalyst surface typically requires acid and redox sites. However, the role of acid-redox interaction on NH 3 -SCR performance is still obscure due to complex acidities and entangled acid-redox sites. Herein, three types of model Ce 2 (SO 4 ) 3 -CeO 2 catalysts with distinct interfaces are constructed to reveal the effect of acid-redox interaction on NH 3 -SCR performance. That is, SO 4 2- /CeO 2 -VS (vapor sulfation of ceria) with strong acid-redox interfacial contact, SO 4 2- /CeO 2 -WI (wet impregnation), and SO 4 2- /CeO 2 -SG (solid grinding) with limited interfaces. It is found the redox property is significantly disturbed as a result of the electron-withdrawing effect from the sulfate. Theoretical result unravels that the introduction of Ce 2 (SO 4 ) 3 retards the oxygen vacancy formation over CeO 2 . Due to restricted interfaces in SO 4 2- /CeO 2 -SG, the negative influence from acid sites is greatly alleviated. Further mechanism study discloses the weakened acid-redox interaction actually changes the nature of surface NO x species, resulting in the generation of reactive species (*O-N-O* and cis -N 2 O 2 2- ) and the promotion of surface reaction via Langmuir-Hinshelwood (L-H) mechanism.
研究领域:
催化化学
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 37
·22780-22788
·
IF 3.361
Xiaoyi Sun,Qingjie Liu,Shuai Liu,Xintang Zhang,Shanshan Liu
A series of MOx–Cr2O3–La2O3/TiO2–N (M = Cu, Fe, Ce) catalysts with nitrogen doping were prepared via the impregnation method. Comparing the low-temperature NH3-SCR activity of the catalysts, CeCrLa/Ti–N (xCeO2–yCr2O3–zLa2O3/TiO2–N) exhibited the best catalytic performance (NO conversion approaching 100% at 220–460 °C). The physico-chemical properties of the catalysts were characterized by XRD, BET, SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. From the XRD and SEM results, N doping affects the crystalline growth of anatase TiO2 and MOx (M = Cu, Fe, Ce, Cr, La) which were well dispersed over the support. Moreover, the doping of N promotes the increase of the Cr6+/Cr ratio and Ce3+/Ce ratio, and the surface chemical adsorption oxygen content, which suggested the improvement of the redox properties of the catalyst. And the surface acid content of the catalyst increased with the doping of N, which is related to CeCrLa/TiO2–N having the best catalytic activity at high temperature. Therefore, the CeCrLa/TiO2–N catalyst exhibited the best NH3-SCR performance and the redox performance of the catalysts is the main factor affecting their activity. Furthermore, in situ DRIFTS analysis indicates that Lewis-acid sites are the main adsorption sites for ammonia onto CeCrLa/TiO2–N and the catalyst mainly follows the L–H mechanism.
研究领域:
催化
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环境科学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL RESEARCH
·
2025
·
IF 7.7
Bo Song,Zhenxing Shen,Qingzhu Tian,Guiling Zhou,Qin Peng,Hao Fan,Jia Liu
Volcanic rock is a natural mineral with a porous structure and rich in various metal oxides. It has been used in environmental applications such as water and soil pollution remediation as stable chemical properties and low cost. In this work, volcanic rock was used in the field of nitrogen oxide control, and the feasibility of preparing NH 3 - Selective Catalytic Reduction catalyst was evaluated. The catalyst AVR-10Mn-450 was prepared by acidification-impregnation-calcination process, and it can achieve more than 90 % denitration effect at 175 °C, 25000 h −1 . It removes nitrogen oxides through the Eley–Rideal and Langmuir–Hinshelwood pathways. AVR-10Mn-450 has the advantages of simple preparation and low cost compared with the mainstream nano-denitration catalysts. It can be applied to the pretreatment of industrial flue gas such as cement plant or glass plant, thereby extending the service life of the precious metal or nano-catalyst at the back end. This work not only realizes the high-value resource utilization of volcanic rock, but also reduces the production cost of denitration catalyst.
研究领域:
环境科学
·
催化化学
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材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2019
·
IF 5.128
Han Jiang,Bin Guan,He Lin,Zhen Huang
This study focuses on investigating the influence of Si/Al ratio on the performance of hydrothermally aged Cu/SSZ-13 catalysts prepared by in situ hydrothermal synthesis method. It was found that NH 3 -SCR performance and hydrothermal stability of Cu/SSZ-13 decreased with increasing Si/Al ratio. Fresh and hydrothermally aged Cu/SSZ-13 with Si/Al ratio of 6.5 showed the best SCR activity and N 2 selectivity in a broad temperature of 200–500 °C, in which more than 90% NO x was reduced with superior N 2 selectivity above 95%. The effect of Si/Al ratio on the properties of the physicochemical structure, the change of acidity intensity, and Cu species migration or transformation of the fresh and aged Cu/SSZ-13 catalysts were comprehensively characterized by NH 3 -TPO, NH 3 -TPD, H 2 -TPR, N 2 physisorption, XRD, ICP-AES, and XPS. The increase of the surface CuO species, the decrease of the amount of Cu 2+ in active sites, the chemisorption NH 3 species, the specific surface area, the total pore volume, and the increase of average pore diameter, may be the main reasons for performance deterioration over high-Si/Al-ratio catalysts after hydrothermal aging. Furthermore, in situ DRIFTS indicate that, with the increasing Si/Al ratio, the zeolitic structure was easy to collapse, and that the surface acid sites, the active copper species, as well as the adsorbed surface nitrate, decreased after hydrothermally aged. After hydrothermal aging, the amount of isolated Cu 2+ decreased, and more CuO species were aggregated, mainly coming from the conversion of the unstable isolated Cu 2+ species in D6R or CHA cages. The decrease of isolated Cu 2+ and CuO species aggregation were significant in Cu/SSZ-13 with high Si/Al ratios. The CuO leaded to the instability of the SSZ-13 skeleton structure and NH 3 oxidation promotion, resulting in catalysts deactivation.
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
MICROPOROUS AND MESOPOROUS MATERIALS
·
2022
·
IF 5.876
En-Hui Yuan,Meng Li,Ming-Hui Yang,Xiaosheng Huang,Kun Zhang,Weiliang Han,Zhicheng Tang,Zhong-Wen Liu
A direct hydrothermal synthesis strategy is developed to prepare the Cu–Fe-ZSM-5 zeolites by using the ethylenediaminetetraacetic acid disodium dihydrate (EDTA-2Na·2H 2 O) chelated Cu 2+ and Fe 3+ precursors as metal sources. During the crystallization, the metal chelates were spontaneously embedded into the ZSM-5 crystals and subsequently transformed to the zeolites encapsulated copper and iron species after removing the chelating agent via the high-temperature calcination . Rigorous characterizations indicate that the resulted Cu 2+ /Cu + and Fe 3+ /Fe 2+ species are formed ultra-small nano-composites with an average diameter of ∼2.2 nm and highly dispersed in the ZSM-5 zeolite crystals. The acidity of the ZSM-5 zeolites is subtly modulated by the encapsulated Cu–Fe nano-composite. As expected, the as-prepared Cu–Fe-ZSM-5 exhibits outstanding catalytic performance for the selective catalytic reduction of NO x with ammonia (NH 3 -SCR) in the broad reaction temperature ranges of 220–480 °C, which is much better than the Cu–Fe/ZSM-5 prepared with the conventional wetness impregnation method. Furthermore, the resultant zeolites show high stability and good tolerance to H 2 O and SO 2 , and it is very competitive for practical application to eliminate NO x . The developed one-pot hydrothermal synthesis route by using EDTA-2Na·2H 2 O as chelating agent is very convenient and easily reproducible, providing a general guideline to design and fabricate the superior transition metal modified zeolite catalysts for NH 3 -SCR and the related reactions.
研究领域:
催化
·
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Xiaofeng Wang,Zhe Zhao,Yang Xu,Qingbo Li
A series of 3DOM-Mn x Ce y Ti z catalysts with three-dimensionally ordered macroporous (3DOM) structure were synthesized by a soft template method. The high SCR activity of the 3DOM-Mn 3 Ce 1 catalyst at low temperature was owing to the excellent redox ability and rich Lewis and Brønsted acid sites of the catalysts, which were beneficial to improve the catalytic activity. However, the strong oxidizability of MnO x resulted in the nonselective oxidation of NH 3 and generation of N 2 O, decreasing the N 2 selectivity. After addition of Ti, the redox capacity of the 3DOM-Mn 3 Ce 1 Ti 1 catalyst decreased, and the NH 3 were strongly adsorbed on the acid sites, which enhanced the N 2 selectivity with a broadened temperature window of 240–440 °C and a high GHSV of 120000 h −1 . Furthermore, both the 3DOM-Mn 3 Ce 1 and 3DOM-Mn 3 Ce 1 Ti 1 catalysts showed remarkable tolerance of H 2 O. Finally, through in situ DRIFT analysis, the Langmuir-Hinshelwood (L-H) mechanism was confirmed as the dominant reaction pathway over the 3DOM-Mn 3 Ce 1 Ti 1 catalyst.
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
CHINESE JOURNAL OF CATALYSIS
·
2025
·
IF 17.7
Ye Wang,Pan Gao,Dan Zhao,Tongrui Liu,Sitong Zhou,Miao Yang,Shiping Liu,Bing Li,Yida Zhou,Wenhao Cui,Guangjin Hou,Peng Tian,Zhongmin Liu
Silicoaluminophosphate (SAPO) molecular sieves possess diverse architectures and exceptional high-temperature hydrothermal stability, rendering them important acid catalysts. However, enhancing acid concentration of certain SAPO materials remains challenging, which limits their catalytic applications. Here, we report the synthesis of a series of SAPO materials using a developed SAPO precursor plus dual template (SPDT) strategy. A variety of SAPO materials characterized by high silica content and enhanced acidity, such as SAPO-34/56 intergrowths, SAPO-56, and SAPO-17, have been synthesized and thoroughly characterized using various techniques including integrated differential phase-contrast scanning transmission electron microscopy, two-dimensional solid-state nuclear magnetic resonance spectroscopy, and continuous rotation electron diffraction. The use of silica-enriched SAPO precursor combined with the flexible selection of the second template enables the crystalline phase regulation and improves the Si atoms incorporation into the framework. Notably, the synthesized SAPO-17 with abundant Si(4Al) species and unprecedentedly high acid density exhibits exceptional DeNO x activity after Cu loading, with NO x conversion exceeding 90% at 175–700 °C. This outstanding performance can be attributed to the unique ERI structure and the increased acidity of SAPO-17. This work not only presents an effective method for synthesizing SAPO molecular sieves with enhanced acidity but also offers a new perspective for expanding the active temperature range of the ammonia selective catalytic reduction reaction.
研究领域:
材料化学
·
催化化学
·
无机非金属材料
·
环境催化
·
分子筛科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Chengzhi Wang,Fengyu Gao,Songjin Ko,Hengheng Liu,Honghong Yi,Xiaolong Tang
The presence of SO 2 in industrial flue gases will cause permanent deactivation of the catalyst active centre. Therefore, an effective method to improve the SO 2 resistance of manganese-based catalysts at low temperatures is urgently needed. In this work, a hierarchical porous nanowire structure catalyst was designed by the in situ self-assembly method to inhibit SO 2 adsorption. This hierarchical porous nanowire aerogel catalyst with great BET surface area and surface acidity exhibited NOx conversion above 90% at 100–400 °C. Notably, the NOx conversion of the MnCe-N catalyst was almost not inhibited by SO 2 (250 ppm) compared to the 33% decrease of the MnCe-P catalyst. On the MnCe-P catalyst, SO 2 has strong competitive adsorption with NH 3 and NO, and the stronger adsorption capacity of SO 2 inhibits the adsorption activation of the reaction gas and hinders the reaction proceeding through the L-H mechanism. Meanwhile, a large quantity of sulfate is formed on the catalyst surface, which prevents the active centre to participate in the redox reaction. The structure of nanowires enhances the number of acid sites, facilitates the adsorption and activation of NH 3 , and effectively inhibits the adsorption of SO 2 on the MnCe-N catalyst. Fewer sulfate species are generated and difficult to deposit and aggregate on the catalyst surface, as a result, the active centre is less affected by sulfate species. The stable adsorption of NH 3 -related species ensures reliable reaction on MnCe-N through the E-R mechanism. This work emphasizes the importance of hierarchically porous structures in improving the NH 3 -SCR performance and SO 2 resistance of monolithic catalysts, and provides new insights into the design of highly efficient and stable catalytic materials.
研究领域:
催化
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）