RSC Advances
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2018
·Vol. 8
·期 5
·2586-2592
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IF 2.936
Boyang Xu,Youlin Liu,Yuesong Shen,Shemin Zhu
A facile method is to prepare novel CeMoxOy-clay hybrid catalysts with layered structures by using organic cation modified clay as support. During the preparation process, cerium cations and molybdate anions are easily adsorbed and impregnated into the interlamellar space of the organoclay, and after calcination they undergo transformation to highly dispersed CeMoxOy nanoparticles within the interlamellar space of the clay. As expected, the prepared CeMo0.15Ox-OC-T catalysts with layered structures had high selective catalytic reduction (SCR) activity such as high NOx conversion of >90% in the wide temperature range of 220–420 °C. Meanwhile, they also exhibit high stability and tolerance to water vapor (5 vol%) and SO2 (200 ppm), demonstrating that these novel catalysts could serve as a good alternative for NH3-SCR in practical application.
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
PubMed
高影响因子
Reaction Kinetics Mechanisms and Catalysis
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2019
·Vol. 128
·期 2
·1065-1077
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IF 1.428
Yu Qifan,Liu Xuesong,Chen Hongfeng,Liu Shuang,Jiang Peng
The regeneration mechanism of sulfated Cu/SAPO-34 catalysts in reducing atmospheres (5% H 2 /Ar and NH 3 /Ar at 600 °C) was investigated by using a series of characterization methods. Hydrogen regeneration improved the catalysts’ NH 3 -SCR activity from 150 to 550 °C remarkably, while ammonia regeneration exhibited relatively less obvious promotion effect. The TPR of hydrogen and EPR spectra data show that the regeneration process affects the amount and the coordination of the active isolated Cu 2+ species significantly. The desulfation increases the amount of isolated copper ions and improves the catalytic activity of SCR.
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
Journal of Materials Chemistry A
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2017
·Vol. 5
·期 19
·9076-9080
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IF 8.867
Xin Xiong,Dingzhong Yuan,Qinming Wu,Fang Chen,Xiangju Meng,Ruihua Lv,Daniel Dai,Stefan Maurer,Robert McGuire,Mathias Feyen,Ulrich Müller,Weiping Zhang,Toshiyuki Yokoi,Xinhe Bao,Hermann Gies,Bernd Marler,Dirk E. De Vos,Ute Kolb,Ahmad Moini,Feng-Shou Xiao
High silica CHA zeolite plays an important role in selective catalytic reduction of NOx with NH3 (NH3-SCR), but its synthesis is not highly efficient due to the use of a relatively high-cost structural directing agent (SDA) N,N,N-trimethyl-adamantammonium hydroxide (TMAdaOH) and relatively long crystallization time under hydrothermal conditions. Herein, we report an efficient and rapid synthesis of a high silica CHA zeolite possessing good crystallinity and uniform crystals (CHA-ST). The method includes interzeolite transformation of high silica FAU zeolite in the absence of water but the presence of zeolite seeds and a bromide form of the SDA. The absence of water in the synthesis significantly improves the zeolite yield by avoiding dissolution of aluminosilicate species in aqueous media, while the addition of zeolite seeds remarkably enhances the crystallization rate under solvent-free conditions. In addition, this route allows the use of a low-cost bromide form of the SDA. Catalytic tests in the NH3-SCR show that copper-exchanged CHA-ST (Cu-CHA-ST) exhibits comparable catalytic properties to those of Cu-SSZ-13 obtained from the conventional hydrothermal route.
研究领域:
材料科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
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2023
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IF 8.6
Xiangsen Xu,Fengye Lyu,Jiahao Chen,Yiqing Zeng,Zhaoxiang Zhong,Feng Zhang,Weihong Xing
In this work, TiO 2 nanocones grown on SiC membrane was used as the support of V 2 O 5 -WO 3 species to prepare V 2 O 5 -WO 3 /TiO 2 @SiC (VWTi(C-X)@SiC) catalytic membrane for dust filtration and NH 3 -SCR denitration. On account of the large specific surface area, abundant surface acid sites and prominent redox property, the optimized VWTi(C-550)@SiC catalytic membrane shows >90% NO removal efficiency at the temperature of 280–360 °C, which are much higher than VWTi(P-550)/SiC catalytic membrane (TiO 2 nanoparticles prepared by traditional vacuum coating titanium sol method was used as the support of V 2 O 5 -WO 3 species, NO conversion <80% at whole tested temperature). Additionally, VWTi(C-550)@SiC displays superior stability during the SO 2 + H 2 O resistance and 300 h long-term test at 300 °C, and exhibits an excellent dust filtration performance (2.5 μm SiO 2 particles interception rate exceeded 99.99%) under all test conditions. More importantly, the structure of nanocones decrease the influence of tensile stresses due to the different thermal expansion coefficients of TiO 2 and SiC membranes, which significantly suppress the fall of VWTi catalyst layer from the surface of SiC during pulse-jet cleaning. Among above results, it can be concluded that the optimized VWTi(C-550)@SiC catalytic membrane shows a prosperous application prospect for the simultaneously dust filtration and NH 3 -SCR denitration of medium–high temperature flue gas .
研究领域:
环境科学
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催化材料
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能源工程
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
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2022
·Vol. 12
·期 11
·1430
·
IF 4.501
Yang Gao,Li Cao,Xiaodong Wu,Xu Zhang,Ziran Ma,Rui Ran,Zhichun Si,Duan Weng,Baodong Wang
CeNbTi catalyst was poisoned in different sulfur poisoning atmospheres at 300 °C for 6 h and then was evaluated for selective catalytic reduction (SCR) of NOxwith NH3. The catalyst deactivation upon SO2exposure was effectively inhibited in the presence of NH3. Temperature-programmed decomposition (TPD) analyses were applied to identify deposit species on the poisoned catalysts by comparison with several groups of reference samples. Diffuses reflectance infrared Fourier transform spectroscopy (DRIFTS) over CeNbTi catalysts with different poisoning pretreatments and gas purging sequences were designed to investigate the roles of NH3in the removal of surface sulfites and sulfates. More ammonium sulfates including ammonium bisulfate and ammonium cerium sulfate were generated instead of inert cerium sulfate in these conditions. The mechanisms about the formation and transformation of surface deposits upon sulfur poisoning w/wo NH3were explored, which provided a basis for developing Ce-based mixed oxides as SCR catalysts for stationary sources.Keywords:ceria;SCR;sulfur;NH3;TPD;DRIFTS;deposit
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
SEPARATION AND PURIFICATION TECHNOLOGY
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2025
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IF 9
Yanping Yang,Shengchen Li,Shunli Shi,Jie Hu,Zexi Xuchen,Shunmin Ding,Dan zhao,Shengjun Deng,Weiming Xiao,Shuhua Wang,Chao Chen
Manganese oxide (MnO x ) catalysts are promising for low-temperature NH 3 -Selective Catalytic Reduction (NH 3 -SCR) with their superior catalytic performance. However, the presence of alkali metals in flue gases, particularly potassium (K), leads to catalyst deactivation and limits their industrial application. This study investigates the synergistic effects of Ce and Nb doping on the K resistance and low-temperature NH 3 -SCR activity of MnO x . The surface acidity and redox properties of MnO x were modulated by Ce and Nb modification. In addition, the phase structure, surface state and active sites of the catalysts were characterized before and after K poisoning. The results indicated that Nb 0.05 Ce 0.05 MnO x exhibited exceptional low-temperature performance, achieving over 90 % NO conversion at 125-250°C, along with significant resistance to K poisoning·NH 3 -TPD and in-situ experiments revealed that the loss of acid sites is the primary cause of K poisoning. The mechanism follows the L-H mechanism with L-acid sites as the main active sites on the catalyst surface and bridging nitrate as the key intermediate state. This research provides valuable insights into enhancing the industrial applicability of MnO x- based catalysts for low-temperature denitrification.
研究领域:
催化化学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
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2021
·Vol. 11
·期 3
·314
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IF 4.146
Lusha Zhou,Jinkun Guan,Chenglong Yu,Bichun Huang
The ethanol dispersion method was employed to synthesize a series of MnOx/SAPO-34 catalysts using SAPO-34 with the hierarchical pore structure as the zeolite carrier, which were prepared by facile acid treatment with citric acid. Physicochemical properties of catalysts were characterized by XRD, XPS, BET, TEM, NH3-TPD, SEM, FT-IR, Py-IR, H2-TRP and TG/DTG. NH3-SCR performances of the hierarchical MnOx/SAPO-34 catalysts were evaluated at low temperatures. Results show that citric acid etching solution at a concentration of 0.1 mol/L yielded a hierarchical MnOx/SAPO-34-0.1 catalyst withca.15 wt.% Mn loading, exhibiting optimal catalytic activity and SO2tolerance at low temperatures. Almost 100% NO conversion and over 90% N2selectivity at 120 °C under a gas hourly space velocity (GHSV) of 40,000 h−1could be obtained over this sample. Furthermore, the NO conversion was still higher than 65% when 100 ppm SO2was introduced to the reaction gas for 4 h. These could be primarily attributed to the large specific surface area, high surface acidity concentration and abundant chemisorbed oxygen species provided by the hierarchical pore structure, which could also increase the mass transfer of the reaction gas. This finding suggests that the NH3-SCR activity and SO2poisoning tolerance of hierarchical MnOx/SAPO-34 catalysts at low temperatures can be improved by controlling the morphology of the catalysts, which might supply a rational strategy for the design and synthesis of Mn-based SCR catalysts.
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
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2020
·Vol. 10
·期 23
·8086-8093
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IF 5.721
Haoxi Jiang,Debin Kong,Ying Niu,Sheng Wang
MnO2–CoOX catalysts with different Mn/Co ratios were prepared using polyvinyl pyrrolidone (PVP) as an assistant to control the morphology and exposed crystal faces of composite oxides. The physicochemical properties of the catalysts were systematically characterized and the catalytic activity of NH3-SCR and resistance to SO2/H2O were investigated. It was found that the NO conversion over Mn–Co-0.2-PVP was apparently higher compared with that over Mn–Co-X-PVP (X = 0.9, 0.8, 0.6, and 0.4). This can be interpreted in terms of exposed crystal surface (110) and enhanced adsorption of NH3/NO, and better redox performance resulting from higher Co3+/Co2+ ratio. Furthermore, different PVP and HAc additives have different H2O and SO2 resistance. Mn–Co-0.2-PVP showed good resistance to H2O and SO2 poisoning owing to having more low-temperature (∼200 °C) NO adsorption sites, which are beneficial to promote the de-NOX reaction and less affected by SO2.
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
CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Peng Lu,Lyumeng Ye,Xianhui Yan,Ping Fang,Xiongbo Chen,Dingsheng Chen,Chaoping Cen
Increasing attentions have been drawn towards the simultaneous removal of toluene in current existing NH 3 -SCR unit. The development of dual-functional catalysts and the understanding of impact induced by toluene addition are momentous but lacking. Herein, a well-reported MnO x -CeO 2 catalyst was chosen as active phase to assess the role of HZSM-5 in this simultaneous removal process. HZSM-5 was found to supply more acid sites especially Lewis acid on the MnO x -CeO 2 catalyst. A MnCe/HZSM-5 catalyst with a SiO 2 /Al 2 O 3 molar ratio of 25 delivered a broad active temperature window of 200–400 °C with NO conversion > 80% and possessed a stable N 2 selectivity > 96% in NH 3 -SCR reaction. Also, it was able to maintain above 60% of toluene conversion in the range of 200–400 °C. More Lewis acid sites, together with abundant Mn 4+ , Ce 3+ and active surface oxygen that formed via the interaction between Mn 4+ /Mn 3+ and Ce 4+ /Ce 3+ (Mn 3+ + Ce 4+ ↔ Mn 4+ + Ce 3+ ), contributed to the superior catalytic performance of MnCe/HZSM-5 with lower SiO 2 /Al 2 O 3 ratio. A reversible catalyst deactivation in NH 3 -SCR induced by toluene was found. Toluene was prone to reacting with NH 3 forming nitriles, which infringed the active sites and decreased the available coordinated NH 3 on Lewis acid sites. In addition, the suppression of NO oxidation to NO 2 that decreasing the percentage of “fast SCR” process, and the inhibition of NH 3 activation to NH 2 species also contributed to the lower SCR activity in the presence of toluene over MnCe/HZSM-5.
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
JOURNAL OF THE ENERGY INSTITUTE
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2022
·
IF 6.47
Pijun Gong,Feng He,Junlin Xie,Haitao Wu
Zn species that exist in the flue gas are dangerous toxicants for SCR catalysts, which will seriously damage its catalytic activity and service life. Hence, the multi-layered nanosheets γ-Al 2 O 3 with (110) facets were introduced into the CeTiOx catalyst to improve the Zn-poisoning resistance performance. Benefiting from the structural and compositional merits, as well as the superior reducibility, abundant acid sites, and chemisorbed oxygen, the 3%Zn–Ce 0.3 -Al 0.4 -Ti catalyst with multi-layered nanosheets structure exhibits excellent NH 3 -SCR activity, over 90% NO conversion between 240 °C and 340 °C. In addition, in situ DRIFTS results suggest the SCR reaction mainly follows L-H and E-R mechanisms on 3%-Ce 0.3 -Al 0.4 -Ti samples, result from the multi-layered nanosheets γ-Al 2 O structure improves the BET specific surface area and Ce 3+ , promotes the adsorption/activation of more NH 3 and NOx species. More interestingly, compared with CeO 2 and TiO 2 the Zn species prefer to absorbed on nanosheets γ-Al 2 O 3 with (110) facets, so it can effectively protect CeO 2 from poisoning as a sacrificial agent .
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
CHEMICAL ENGINEERING JOURNAL
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2022
·
IF 16.744
Wen Luo,Jing Rong,Wanxia Zhao,Keke Kang,Lulu Long,Xiaojiang Yao
CeO 2 –TiO 2 catalysts with four different morphologies were successfully synthesized by a hydrothermal method and tested for selective catalytic reduction of NO x with NH 3 (NH 3 –SCR). For the four catalysts, CeO 2 –TiO 2 nanocubes (CT–NC) and nanorods (CT–NR) preferentially exposed {1 0 0} and {1 1 0} facets, respectively; furthermore, nanosheets (CT–NS) and nanospheres (CT–NH) mainly exposed {1 1 1} facet. Interestingly, CT–NH catalyst showed the best NH 3 –SCR performance and the NO x conversion exceeded 97% at 325 °C. Through a series of characteristic methods manifested that the short–range ordered structure of Ce–O–Ti in CT–NH catalyst provided stronger surface acidic sites to promote the high–temperature activity. Moreover, the abundant Ce 3+ species and appropriate reduction ability on {1 1 1} facet of CT–NH catalyst also caused outstanding de NO x activity. Reaction mechanism study showed that the Langmuir–Hinshelwood (L–H) mechanism and Eley–Rideal (E–R) mechanism existed simultaneously on all catalysts in NH 3 –SCR reaction. Meaningfully, two types of E–R mechanism were present on CT–NH catalyst, while L–H mechanism was dominant.
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
Molecular Catalysis
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2018
·
IF 0
Sher Ali,Yushi Li,Tianrui Zhang,Syed ul Hasnain Bakhtiar,Xuesong Leng,Zhibin Li,Fulong Yuan,Xiaoyu Niu,Yujun Zhu
Citric acid method was employed to prepare a series of Nb-promoted Fe x -Nb 0 . 5- x -Ce 0.5 ( x = 0.45, 0.4, 0.35) oxides for selective catalytic reduction with NH 3 (NH 3 -SCR) of NO process. The structure, redox ability and reactivity of NH 3 and absorbed NO species on the catalysts were explored by using various characterization techniques such as X-ray diffraction (XRD), temperature program reduction with H 2 (H 2 -TPR), temperature program desorption of NH 3 (NH 3 -TPD), temperature program desorption of NO (NO-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). It was found that the Nb promoted Fe x -Nb 0 . 5- x -Ce 0.5 ( x = 0.45, 0.4, 0.35) oxides catalysts showed outstanding NH 3 -SCR of NO activity, excellent N 2 selectivity and remarkable SO 2 /H 2 O resistance, meanwhile, Fe 0.4 -Nb 0.1 -Ce 0.5 exhibited above 90% NO conversion in the range of 180–400 °C, together with near 100% N 2 selectivity. The characterization results point out that the excellent catalytic performance of Fe 0.4 -Nb 0.1 -Ce 0.5 can be ascribed to the strong interaction among Nb, Fe and Ce oxides. The strong interaction not only increases the BET surface area and redox ability of the catalyst, but also significantly improves the acid amount leading to the enhancement of the adsorption and activation of NH 3 , which is advantage of the reactivity of adsorbed nitrate together with the adsorbed NH 3 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
危险品化学品经营许可证（带存储）