FUEL
·
2024
·
IF 6.7
Qitong Xue,Jiaying Xing,Jianjun Chen,Jinxing Mi,Jianqiang Shi,Yao Wang,Junhua Li,Zhiming Liu
V 2 O 5 /TiO 2 has been wide used in the selective catalytic reduction of NO x by NH 3 (NH 3 -SCR). However, the poisoning mechanism of thallium (Tl) on the catalytic performance of commercial V 2 O 5 /TiO 2 catalyst has remained unclear. Herein, we have systematically investigated the poisoning effect of Tl based on the different characterizations and DFT calculations. It was found that the strong interaction between V and Tl exists, resulting in the transformation of V from monomeric VO x to polymeric and crystalline VO x , the formation of V-O-Tl species, a decrease in the active V 5+ sites, and the inhibition of the adsorption and activation of NH 3 on both Brønsted and Lewis acid sites. Mechanistic studies further confirmed that inactive nitrate intermediate species gradually accumulated over V 2 O 5 /TiO 2 catalyst surface due to the presence of Tl. A combination of factors ultimately led to the deactivation of the V 2 O 5 /TiO 2 catalyst. This study unveils the poisoning mechanism of Tl on V-based catalysts and shed light on the design of Tl-tolerant NH 3 -SCR catalysts.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Sustainability
·
2022
·Vol. 14
·期 9
·5353
·
IF 3.889
Kun Li,Tao Zhou,Xinqiang Xu,Changye Han,Hua Zhang,Jiang Jin
Mn-Co-based catalysts were loaded to ceramic filters element by impregnation for the coprocessing of dust and nitrogen oxide (NOx) in flue gas. The influence of the Mn/Co ratio and loading on the catalytic performance was investigated. The Mn-Co-based catalytic ceramic filter with a Mn/Co molar ratio of 2/1 can achieve 99% NO conversion by selective catalytic reduction of NOxwith NH3(NH3-SCR) in the temperature range of 100−180 °C, but its resistance to H2O was relatively poor. The filter element was modified by PTFE to improve the H2O resistance. After modification, the catalytic ceramic filter showed superior resistance to H2O and SO2at low temperatures (100–180 °C) and satisfactory self-cleaning performance.Keywords:NH3-SCR;catalytic ceramic filter;PTFE-modified;H2O resistance
研究领域:
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
·
2018
·Vol. 8
·期 7
·3858-3868
·
IF 2.936
Shuohan Yu,Sheng Xu,Bowen Sun,Yiyang Lu,Lulu Li,Weixin Zou,Peng Wang,Fei Gao,Changjin Tang,Lin Dong
Chromium oxide nano-particles with an average diameter of 3 nm covered by amorphous carbon (CrOx/C) were successfully synthesized. The synthesized CrOx/C materials were used for the selective catalytic reduction of NOx by NH3 (NH3-SCR), which shows superb NH3-SCR activity and in particular, satisfactory regeneration ability in the presence of SO2 compared with Mn-based catalysts. The as-prepared catalysts were characterized by XRD, HRTEM, Raman, FTIR, BET, TPD, TPR, XPS and in situ FTIR techniques. The results indicated presence of certain amounts of unstable lattice oxygen exposed on the surface of CrOx nano-particles with an average size of 3 nm in the CrOx/C samples, which led to NO being conveniently oxidized to NO2. The formed NO2 participated in NH3-SCR activity, reacting with catalysts via a “fast NH3-SCR” pathway, which enhanced th NH3-SCR performance of the CrOx/C catalysts. Furthermore, the stable lattice of the CrOx species made the catalyst immune to the sulfation process, which was inferred to be the cause of its superior regeneration ability in the presence of SO2. This study provides a simple way to synthesize stable CrOx nano-particles with active oxygen, and sheds light on designing NH3-SCR catalysts with highly efficient low temperature activity, SO2 tolerance, and regeneration ability.
研究领域:
催化
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环境工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2025
·
IF 6.6
Zhenyun Tian,Weichao Zheng,Liu Yang,ChuanMing Wu,Jialong Kang,Jiawen Chen,Guibao Qiu
The recovery of valuable metals from spent SCR catalysts currently centers on chromium and tungsten oxides. However, this approach demands substantial consumption of acids and bases, and due to the low vanadium and tungsten content, its economic output is minimal. In contrast, titanium dioxide, which exists in significantly higher proportions within the catalyst, is largely overlooked, aggravating environmental issues and leading to considerable resource wastage. This research proposes utilizing spent SCR catalysts as raw materials to directly synthesize titanium alloys, thereby increasing the recovery value of these discarded materials. The findings reveal that aluminum, employed as a reducing agent, efficiently reduces the majority of valuable metals in the catalyst, resulting in the formation of titanium alloys. Furthermore, the addition of calcium oxide markedly enhances the reduction process and improves slag-metal separation. When the CaO content reaches 50 wt%, titanium recovery achieves an impressive rate of 93.34 wt%. The produced alloy comprises primarily a Ti–Al alloy matrix, with a Ti–Si alloy as a dispersed reinforcing phase uniformly distributed within the matrix, demonstrating significant potential for practical applications.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Environmental Science & Engineering
·
2017
·Vol. 12
·期 1
·1-7
·
IF 1.716
Shi Jin,Zhang Zihao,Chen Mingxia,Zhang Zhixiang,Shangguan Wenfeng,Gu Shunchao,Shin-ichi Hirano
Fe-BEA catalysts are active for the NH3-SCR of NO. For industrial application, a binder should be added to the Fe-BEA catalysts to make them tightly adhere to the monoliths. The addition of alumina and zirconia as binders to the Fe-BEA led to a different effect on NO conversion. The catalytic activity of the mixed samples was evaluated by the temperature programmed procedure in a flow-reactor system, and the mechanism was analyzed via SEM, BET, XRD and XPS. It was found that larger iron particles were formed by the migration of parent iron particles in the Fe-BEA catalyst with alumina. This led to the increase of Fe 3+ magnitude and iron cluster, enhancing the abilities of NO oxidation and storage. Accordingly, the SCR activity increased slightly in low temperature but decreased sharply in high temperature. For the Fe-BEA with zirconia sample, NO oxidation and storage abilities decreased due to the less iron clusters. The increase of Fe 3+ magnitude resulted in higher catalytic oxidation ability, which gave rise to little change in the SCR activity compared with the Fe-BEA.
研究领域:
催化
·
环境科学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Chen Cai,Jiayin Chen,Wei Fu,Shuying Ning,Hao Zhou,Muhammad Kashif,Yaxin Su
The Ce-modified OMS-2 catalyst (Ce x -OMS-2) was synthesized by the hydrothermal synthesis method, after which its catalytic efficacy in the selective reduction of NO by CO was assessed. The experiments showed that Ce 0.08 -OMS-2 was capable of 100% NO conversion between 175 and 300 °C when 0.05%NO, 0.1%CO, 5%O 2 and N 2 were used as equilibrium gases, and the N 2 selectivity peaked at 93.2% at 175 °C. Additionally, Ce 0.08 -OMS-2 exhibits good sulfur resistance in the presence of 0.02% SO 2 and maintains more than 88% NO conversion at 175–275 °C. By using BET, XPS, H 2 -TPR, NH 3 -TPD, and In situ DRIFTS to characterize the catalysts, the effects of doping the active metal Ce on the physicochemical characteristics of OMS-2 catalysts were under investigation. In conclusion, the improvement of the low-temperature activity of the Ce x -OMS-2 catalyst is facilitated by lower agglomeration and crystallinity , larger specific surface area, smaller average pore size, enhanced surface oxygen vacancies, increased Mn 4+ concentration, and richer Brønsted acid. Reaction gas adsorbed species and intermediates on the catalyst surface were dynamically captured during In situ DRIFTS experiments. The CO-SCR reaction of the catalyst was found to follow the E-R mechanism below 200 ℃ and the L-H mechanism at 200–350 ℃.
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
Molecular Catalysis
·
2018
·
IF 0
Jun Huang,He Huang,Licheng Liu,Hongtao Jiang
MnO x based catalysts exhibit excellent low-temperature activity in the selective catalytic reduction (SCR) of NO x by NH 3 . The effect of Mn oxidation state (chemical valence) on the NH 3 -SCR activity is an interesting topic and important for designing an active catalyst. This study aimed to clarify the intrinsic effect of Mn valence in NO-SCR reaction. For this purpose, the pure MnO x (MnO, Mn 3 O 4 , Mn 2 O 3 , MnO 2 ) and physical mixed 30% MnO x /TiO 2 catalysts, as well as three Mn/TiO 2 catalysts prepared by impregnation, were investigated for the low temperature NO-SCR with NH 3 in the presence of excess O 2 . The catalysts were characterized by N 2 adsorption, X-ray diffraction (XRD), X-ray Absorption Fine Structure (XAFS), and temperature programmed reduction of H 2 (H 2 -TPR) to probe the physical and chemical properties of catalysts. The MnO x with different chemical valence exhibited distinct intrinsic activity. The Mn 3 O 4 and MnO/TiO 2 showed the highest intrinsic activity (TOR) for the unsupported and supported catalysts, respectively. The MnO x species with low chemical valence (MnO, Mn 3 O 4 ) exhibited overall high intrinsic SCR activity (larger than 0.012 NO h −1 nm −2 MnOx ). The MnO x with different valence normally changed to higher oxidation state after physically mixed with TiO 2 . The content of MnO x species with different valence depended on their loading and Mn precursor, showing a totally different constitution. This work provides new insights into the Mn valence effect on the intrinsic activity for low-temperature SCR.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
FUEL PROCESSING TECHNOLOGY
·
2016
·
IF 3.847
Wei Li,Rui-tang Guo,Shu-xian Wang,Wei-guo Pan,Qi-lin Chen,Ming-yuan Li,Peng Sun,Shu-ming Liu
Heavy metals (such as Zn and Pb) have a deactivation effect on the catalyst for selective catalytic reduction of NO with NH 3 . In this study, it was found that the modification of Mn/TiO 2 catalyst by Nb could greatly enhance its Zn resistance. From the characterization results of BET, XRD, H 2 -TPR, NH 3 -TPD, it may be concluded that the introduction of Nb into Mn/TiO 2 catalyst would lead to its lower crystallinity , more acid sites and higher concentrations of Mn 4 + and surface chemisorbed oxygen. The results of in situ DRIFT study reveal that the NH 3 -SCR reactions over Mn/TiO 2 and Mn-Nb/TiO 2 all obey both the Langmuir-Hinshelwood mechanism and the Eley–Rideal mechanism, and the doping of Nb on Mn/TiO 2 catalyst could promote the adsorption of NH 3 and NOx species on it. All these features make a contribution to the high SCR activity and good Zn resistance of Mn-Nb/TiO 2 catalyst.
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
Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Bo Wang,Qiaowen Yang
Large amounts of spent selective catalytic reduction (SCR) catalysts were produced in industry after losing their activity. This study developed a clean and effective route of leaching and recovery of vanadium (V) from spent SCR catalyst. First, ascorbic acid (C 6 H 8 O 6 ) as the adjuvant can enhance vanadium leaching in H 2 SO 4 solution. The effect parameters of acid concentration, leaching temperature, leaching time and liquid-solid (L/S) ratio on the leaching efficiency of vanadium were investigated. Then, the enrichment of vanadium in the leachate to obtain the black cake was carried out through adjusting pH value. The effects of vanadium concentration and pH on the precipitation efficiency of vanadium were studied. Finally, after alkaline dissolution and oxidation of the black cake, ammonium chloride (NH 4 Cl) was selected and used as the precipitant to obtain the ammonium poly-vanadate (APV). The final product vanadium pentoxide (V 2 O 5 ) was obtained through roasting APV at 550 ℃ for 1.0 h. The black cake, APV and V 2 O 5 were analyzed by the characterization of XRD or XRF . This study may introduce a new perspective for the effective usage of vanadium from spent SCR catalyst.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2022
·Vol. 9
·期 6
·1300-1312
·
IF 7.779
Nangui Lv,Chenhu Sun,Xueqin Wang,Chan Wang,Yuanyuan Yue,Xiaojun Bao
Synthesizing CHA-type zeolite via template-free interzeolite transformation has been considered as a green method, but the resultant zeolite exhibits low activity in the selective catalytic reduction of NOx by ammonia (NH3-SCR). Herein we report a highly active NH3-SCR catalyst (Cu-CHAUSY) derived from CHA-type zeolite (CHAUSY) that is synthesized via template-free interzeolite transformation from ultra-stable Y (USY). The ultra-high activity is attributed to the specific silicon and aluminum configurations in USY which are distinctly different from those in the conventionally used parent NaY, although they have similar SiO2/Al2O3 ratios. This characteristic endows CHAUSY with more single Al atoms in a six-membered ring, benefiting the self-reduction of [Cu(OH)]+ and the activation of O2 during the NH3-SCR reaction. Moreover, Cu-CHAUSY is demonstrated to outperform the two reference catalysts prepared from the aluminosilicate gel by conventional hydrothermal crystallization with the assistance of organic templates. Our work provides a new strategy for preparing highly active NH3-SCR catalysts.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
高影响因子
Molecular Catalysis
·
2022
·
IF 5.089
Yaping Yang,Xuesong Liu,Zhiming Sui,Yanghui Wang,Ping Fang,Peng Jiang,Xiaodong Wu
The purpose of this study is to investigate the interaction of Ce and W species with TiO 2 , Al 2 O 3 and SiO 2 supports, so as to illustrate the influence of supports and distribution of Ce, W species on SCR reaction. It is found that low-temperature activity followed the order of CeW > CeWTi > CeWAl > CeWSi. The reasons for the various activity of the catalyst were investigated by a series of characterization. The low-temperature NH 3 -SCR activity is associated with the surface concentrations of Ce 3+ , oxygen vacancies and active oxygen species, which are dominated by the dispersion and interactions of Ce/W species with the supports. Arising from interactions of Ti 4+ with high-density electron cloud, finely dispersed Ce and W species facilitate the W-Ce synergism and produce more active oxygen. All these contribute toTiO 2 can make Ce and W species in an ideal distribution, so the corresponding catalyst shows excellent NO x conversion of CeWTi catalyst at 200–350 °C. The reaction process observed by in situ DRIFT indicated that the NH 3 -SCR reaction on CeO 2 -WO 3 containing catalysts mainly follow Langmuir-Hinshelwood (L-H) mechanism at low temperature. Based on the analysis of the characterization and reaction process, it is concluded that the control step of NH 3 -SCR reaction at low temperature over CeO 2 -WO 3 containing catalysts is the adsorption and activation of NO x .
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
危险品化学品经营许可证（带存储）