COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2019
·
IF 3.131
Boqiong Jiang,Beilong Lin,Zhiguo Li,Shuang Zhao,Ziying Chen
A series of Mn/TiO 2 catalysts were prepared by ultrasonic spray pyrolysis (USP) method for selective catalytic reduction (SCR) of NOx from flue gas at low temperatures. The highest activity of Mn/TiO 2 was obtained with a Mn/Ti ratio of 0.5. When Fe was doped into Mn(0.5)/TiO 2 , the NOx conversion rate on Fe(0.05)-Mn(0.5)/TiO 2 was increased by approximately 10 % at 120–180 °C. The samples were characterized by XRD , SEM , H 2 -TPR, and N 2 adsorption analyses. Results revealed that Mn(0.5)/TiO 2 with Mn/Ti ratio of 0.5 presented the lowest crystallinity , the highest surface area, and the highest redox ability. Although the surface area was significantly decreased by Fe doping, it also reduced the crystallinity and crystal size of the catalysts, thereby increasing the O concentration on the surface of catalyst. Moreover, Fe(0.05)-Mn(0.5)/TiO 2 displayed a higher redox ability than the other catalysts. At 120–240 °C, the activation energy decreased from 27.65 kJ/mol on Mn(0.5)/TiO 2 to 14.46 kJ/mol on Fe(0.05)-Mn(0.5)/TiO 2 , thereby facilitating the activation of the reaction on Fe(0.05)-Mn(0.5)/TiO 2 . Despite that the NO and NH 3 adsorptions were lower on Fe(0.05)-Mn(0.5)/TiO 2 than on Mn(0.5)/TiO 2 , the intermediates on Fe(0.05)-Mn(0.5)/TiO 2 , particularly nitrates, were easily activated to participate in the reaction, leading to increasing catalytic activity.
研究领域:
环境科学
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催化材料
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Xinyu Li,Huawang Zhao,Yating Huang,Xiaomin Wu,Zhiwei Huang,Huazhen Shen,Guohua Jing
A composite catalyst was prepared by mechanically mixing Cu-SSZ-13 and MnCeTiO x to improve selective catalytic reduction (SCR) of NO x by ammonia. The optimal mass ratio of Cu-SSZ-13 and MnCeTiO x components in the composite catalysts was 1:1, where the NO x conversion was improved by around 40% in the temperature range of 150–300 °C compared with Cu-SSZ-13 alone. MnCeTiO x presented significantly stronger ability on the activation of NO to nitrates species than Cu-SSZ-13. Infrared (IR) and density functional theory (DFT) results showed that active nitrates intermediate on MnCeTiO x might migrate to Cu-SSZ-13, which assisted the oxidation of single Cu + to Cu 2+ to complete the Cu redox cycle. This avoided the rate-determining step that formation and oxidation of Cu + dimers in low-temperature SCR over Cu-SSZ-13. The research results are beneficial to the rational design of SCR catalysts with high-performance at low temperatures.
研究领域:
催化化学
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环境科学
✓ 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
Engineering
·
2025
·
IF 11.6
Ying Zhu,Jingjing Liu,Guangzhi He,Shaohua Xie,Wenpo Shan,Zhihua Lian,Fudong Liu,Hong He
Catalytic activity and hydrothermal stability are both crucial for the application of the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR catalyst) in diesel vehicles. In this study, a tin (Sn)-modified Ce–Nb mixed-oxide catalyst was synthesized as an NH 3 -SCR catalyst for NO x emission control. After the introduction of Sn, both the NH 3 -SCR activity and the hydrothermal stability of the catalyst were remarkably promoted. Even after hydrothermal aging at 1000 °C, the developed Ce 1 Sn 2 Nb 1 O x catalyst achieved more than 90% NO x conversion at 325–500 °C. Various methods, including N 2 -physisorption, X-ray diffraction, in-situ high-temperature X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray absorption fine-structure spectroscopy, temperature-programmed reduction of hydrogen, temperature-programmed desorption of ammonia, and density functional theory calculations were used to investigate the promotional effects induced by the Sn species. The characterization results showed that the addition of Sn not only promoted the formation of the Ce–Nb active phase but also improved its thermal stability, contributing to the excellent NH 3 -SCR performance and hydrothermal stability. This study provides an excellent sintering-resistance catalyst for the application of diesel engine NO x emission control.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Yixi Wang,Wenqing Xu,Zhi Liu,Yulong Shan,Wanrong Chen,Xinyu Zhang,Tingyu Zhu
Controlling both CO and NOx pollutants without additional cost is necessary but challenging, especially in industrial flue gas with complex components. Previous studies mainly focused on the effect of O 2 and SO 2 on the CO oxidation side reaction and valence state of Ir species on various catalysts, while neglecting the impact on NO conversion pathway. Herein, we propose an "ineffective reaction pathway" in the presence of O 2 with nitrate as an intermediate according to the results of in situ DRIFTS and DFT. And we also reveal the contribution of SO 2 in inhibiting the adsorption of O 2 and promoting the selective adsorption of NO and CO even at lower injection concentrations, based on the oxidation of SO 2 on Ir(111). This is quite a favorable characteristic for the treatment of industrial flue gas, resolving the long–standing dispute on the involvement of these components in the CO–SCR reaction. Under specific conditions (CO/NO=20, O 2 =5%, SO 2 =200 ppm) at 250 °C, the NOx conversion is as high as 78%. These results will contribute to the development of more efficient catalysts in the future for simultaneously controlling two pollutants (CO and NOx).
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 16
·3747
·
IF 4.2
Guanyu Chen,Weixin Zhang,Rongshu Zhu,Yanpeng Chen,Minghu Zhao,Mei Hong
Zeolite-based catalysts efficiently catalyze the selective catalytic reduction of NOxwith methane (CH4-SCR) for the environmentally friendly removal of nitrogen oxides, but suffer severe deactivation in high-temperature SO2- and H2O-containing flue gas. In this work, SSZ-39 zeolite (AEI topology) with high hydrothermal stability is reported for preparing CH4-SCR catalysts. Mild acid leaching with oxalic acid (OA) not only modulates the Si/Al ratio of commercial SSZ-39 to a suitable value, but also removes some extra-framework Al atoms, introducing a small number of mesopores into the zeolite that alleviate diffusion limitation. Additional Co3O4modification during indium exchange further enhances the catalytic activity of the resulting In-Co3O4/H-SSZ-39(OA). The optimized sample exhibits remarkable performance in CH4-SCR under a gas hourly space velocity (GHSV) of 24,000 h−1and in the presence of 5 vol% H2O. Even under harsh SO2- and H2O-containing high-temperature conditions, it shows satisfactory stability. Catalysts containing Co3O4components demonstrate much higher CH4conversion. The strong mutual interaction between Co3O4and Brønsted acid sites, confirmed by the temperature-programmed desorption of NO (NO-TPD), enables more stable NxOyspecies to be retained in In-Co3O4/H-SSZ-39(OA) to supply further reactions at high temperatures.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2014
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IF 6.007
Fredrik Gunnarsson,Moa Z. Granlund,Mattias Englund,Jazaer Dawody,Lars J. Pettersson,Hanna Härelind
We report on a high NO x reduction activity over Ag/Al 2 O 3 catalysts, using hydrogen produced in a fuel reformer. The focus of the study is to evaluate the performance of a hydrocarbon selective catalytic reduction (HC-SCR) catalyst in real conditions. Initially, the catalytic materials for the fuel reformer (Rh/CeO 2 -ZrO 2 ) and the HC-SCR (Ag/Al 2 O 3 ) were evaluated in separate bench-scale reactor setups. These two setups were subsequently joined into an integrated bench-scale reactor setup with the aim to evaluate the influence of the reformate on the HC-SCR activity in a controlled environment. In the final phase of the study a 4 wt.% Ag/Al 2 O 3 catalyst doped with 100 ppm(w) Pt was scaled up and tested in a pilot-scale reactor setup. The pilot-scale reactor setup enabled evaluation of the HC-SCR activity in real exhaust gases generated by a single cylinder engine (genset) together with a hydrogen-rich gas supplied from a fuel reformer. Commercial biodiesel (NExBTL) was used as reducing agent for the HC-SCR as well as fuel in the fuel reformer for both the bench-scale and pilot-scale experiments. This study gives an excellent link between evaluations of the catalytic materials, controlled bench-scale experiments and applied engine experiments, proving a viable concept for lean NO x reduction together with onboard hydrogen production. A NO x conversion of above 70% was reached at temperatures below 250 °C, in bench-scale experiments when hydrogen produced in the fuel reformer is added.
研究领域:
环境科学
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催化化学
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能源工程
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2020
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IF 3.687
Yiqing Zeng,Zihua Wu,Lina Guo,Yanan Wang,Shule Zhang,Qin Zhong
The problems of easily inactivated by SO 2 poisoning and high N 2 O formation for MnO x based catalysts hinder its application in selective catalytic reduction (SCR) of NO x with NH 3 . The SO 2 poisoning mechanism has been well demonstrated, but the N 2 O formation mechanism was still controversial due to previous limited study. Herein, MnO 2 supported on MO x (Mn/M, M = Al, Si and Ti) were prepared by wet impregnation method to investigate the carrier effect on the formation of N 2 O. Although all of selected supports had a large amount of surface acid sites, only forming strong active-support interaction can separate the activation sites of NH 3 and NO + O 2 . Accordingly, the activation of NH 3 and NO + O 2 on MnTi was respectively occurred on TiO 2 and MnO 2 , but both NH 3 and NO + O 2 was activated on MnO 2 over MnAl and MnSi samples. The over-activation (NH 2 dissociated into NH) of NH 3 would be effectively inhibited when NH 3 activation was occurred on TiO 2 , thus it can significantly suppress the formation of N 2 O. In contrast, the NH 3 species would sharply decompose into NH on MnO 2 and then lead to the high amount of N 2 O. Finally, we proposed some methods that might effectively improve the selectivity of MnO x- based catalysts.
研究领域:
环境科学
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催化化学
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Huixian Zhou,Hui Zhong,Yiqing Zeng,Yutang Kang,Bin Chen,Shuanglu Ma,Yifan Li,Yu Zhang,Shasha Feng,Zhaoxiang Zhong,Weihong Xing
The strategy of constructing catalytic membrane has a significant influence on its structure and performance. In this work, Co 3 O 4 -C x @SiO 2 nanofiber membranes (NFMs) were fabricated by an in-situ growth–pyrolysis–oxidation strategy. The Co 3 O 4 -C x catalyst derived from ZIF-67 was wrapped around nanofibers, which helps to maintain a stable membrane structure, then suppressing the reduction of gas permeability. Among the Co 3 O 4 -C x catalyst, the carbon skeleton can prevent the agglomeration of Co 3 O 4 nanoparticles, obtaining an ultra-fine Co 3 O 4 nanoparticles with high dispersibility, redox property and surface area. The obtained Co 3 O 4 -C 300 @SiO 2 NFM exhibits outstanding ammonia selective catalytic reduction (NH 3 -SCR) denitrification activity (T 90 = 225 °C at a GHSV of 77,000 h −1 ). The effect of catalyst loading on PM 2.5 filtration performance of SiO 2 NFM was also tested. Co 3 O 4 -C 300 @SiO 2 NFM has higher filtration efficiency (99.99%) than SiO 2 NFM at a lower pressure drop of 58 Pa, which suggests that catalyst loading via our method can improve the filtration performance of SiO 2 NFM. This work might provide a universal strategy for the design and preparation of highly efficient catalytic membrane.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2023
·
IF 22.1
Wang Song,Qianni Cheng,Li Han,Jiawei Ji,Yandi Cai,Wei Tan,Jingfang Sun,Changjin Tang,Lin Dong
Manganese oxide-based catalysts exhibit excellent low-temperature denitration efficiency, making them potential candidates for application. Herein, the relationship between reaction stability and phase structure for MnO 2 , Mn 2 O 3 and Mn 3 O 4 was disclosed. The NO conversion for Mn 2 O 3 drastically reduced after 120 h reaction, while minor decline was detected for MnO 2 and Mn 3 O 4 . Based on dedicate qualitative and quantitative analyses on the deposits over catalyst surface, deactivation trigged by ammonium nitrate (AN) deposition was confirmed. Different from penta-coordinated Mn 4+ on MnO 2 (110) and tri-coordinated Mn 2+ , penta-coordinated Mn 4+ on Mn 3 O 4 (101), the unique tetra-coordinated Mn 3+ on Mn 2 O 3 (200) could stabilize the nitrates and make it difficult to be removed via decomposition or reaction and accumulate continuously, which resulted in the significant deactivation. This research could not only unveil the poisoning mechanism of MnO x based catalysts, but also provide new insights into the relationship between the catalytic stability and surface Mn-O microstructure.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
AICHE JOURNAL
·
2022
·Vol. 68
·期 11
·e17834
·
IF 4.167
Wuyuan Liu,Zhaoying Wang,Ming Sun,Jiajian Gao,Lifeng Wang,Zihan Gao,Yingying Xu,Xiangyun Zhao,Cheng Zhang,Lin Yu
A series of CeO 2 modified Cu-SSZ-13 monolith catalysts were prepared by embedding CeO 2 into the washcoat of Cu-SSZ-13 monolith catalyst through solvent combustion method. These CexCu-SSZ-13 catalysts were studied in the selective catalytic reduction (SCR) of NO with NH 3 , among which the Ce2Cu-SSZ-13 catalyst exhibited the best low-temperature activity, hydrothermal stability, and sulfur resistance. The physicochemical properties of the catalysts were characterized using multiple methods. Results showed that the acidity, redox capacity, and ammonia adsorption capacity significantly enhanced after CeO 2 modification, thus leading to the high performance of Ce2Cu-SSZ-13 catalyst. Furthermore, the introduction of CeO 2 induced the fast SCR reaction by promoting the oxidation of NO to NO 2 . Analog calculation suggested that the porous structure generated via solvent combustion in the washcoat effectively increased the diffusion rate of reaction. In situ diffuse reflectance infrared Fourier transform spectroscopy ( in situ DRIFT) analysis showed that Brønsted acid sites were the main active center and the reaction followed 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
Journal of Cleaner Production
·
2022
·
IF 11.072
Jiajin Huang,JiaYu Chen,Jinze Yao,Siyao Zhao,Xingbei Wu,Qibin Xia
The challenge for selective catalytic reduction (SCR) of NO x with NH 3 is to improve de-NO x activity at low temperatures while simultaneously improving the tolerance of catalysts towards SO 2 poisoning. Herein, V and Ce oxides were loaded on deactivated SCR catalysts subjected to acid pickling (CAT) via impregnation to recover de-NO x activity. The resulting V–Ce@CAT catalyst exhibited 85–95% NO x conversions over a wide temperature window of 200–450 °C while conversions of only 40–78% over the same temperature range were observed with CAT (spent catalyst treated with acid). Interestingly, in addition to the high tolerance towards SO 2 displayed by V–Ce@CAT, the catalyst exhibited improved reactivity after the introduction of 200 ppm SO 2 , with the NO x conversion increasing from 80% to 87%. The results indicated that a kinetic equilibrium was reached between the formation and decomposition rates of Ce 2 (SO 4 ) 3 on V–Ce@CAT which prevented the accumulation of surface sulfate species, thereby protecting the main active species V from catalytic inactivation. Furthermore, in situ DRIFTS revealed that the NH 3 -SCR reaction pathway of V–Ce@CAT follows the L-H mechanism.
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
危险品化学品经营许可证（带存储）