scholarly journals Recent advances in heighten sulfur resistance of SCR catalysts: A review

2021 ◽  
Vol 27 (1) ◽  
pp. 200642-0
Author(s):  
Ling Zhao ◽  
Yu Zhang ◽  
Mengdi Kang
Keyword(s):  
Catalytic Reduction ◽  
Sulfur Poisoning ◽  
Environmental Catalysis ◽  
Nox Removal ◽  
Sulfur Resistance ◽  
Positive Role ◽  
Scr Catalysts ◽  
Denox Catalysts ◽  
Development Direction

NOx removal by selective catalytic reduction (SCR) technology is a research hotspot in the field of environmental catalysis, and this method is dominated by catalysts. However, denitrification catalyst is easy to be polluted by the presence of SO2, which seriously restricts its practical industrial application. This review focuses on the latest domestic and foreign research results and advancement in improving sulfur resistance of deNOx catalysts, reveals the sulfur poisoning mechanism and regeneration process, as well as introduces the positive role of quantum chemistry in the field of sulfur resistance. In view of the questions set forth in this review, the future development direction of deNOx catalysts is prospected, which provides valuable scientific guidance for the design and development of efficient and practical sulfur resistant deNOx catalysts.

Insights into sulfur poisoning and regeneration of Cu-SSZ-13 catalysts: In situ Cu and S K-edge XAS studies

2021 ◽  
Author(s):  
Vitaly Mesilov ◽  
Sandra Dahlin ◽  
Susanna Liljegren Bergman ◽  
Peter Sams Hammershøi ◽  
Shibo Xi ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Catalytic Reduction ◽  
Sulfur Poisoning ◽  
X Ray ◽  
Scr Catalysts ◽  
X Ray Absorption

In situ Cu and S K-edge X-ray absorption spectroscopy (XAS) was used for the investigation of sulfur-poisoned and regenerated Cu-SSZ-13 selective catalytic reduction (SCR) catalysts. Sulfur in the oxidation state...

scholarly journals Effects of Ce over TiO2 supported MnOx-based Catalyst for NOx Reduction by Ammonia

2020 ◽  
Vol 185 ◽  
pp. 04026
Author(s):  
Zhi Liu ◽  
Yunqi Liu
Keyword(s):  
Catalytic Reduction ◽  
Nox Reduction ◽  
Catalyst Design ◽  
No Oxidation ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Positive Role ◽  
Fast Scr ◽  
Insight Into

Ce modified MnOx-based catalysts have attracted much attention due to its high activity for selective catalytic reduction of NOx by NH3 (NH3-SCR) at low-temperatures. However, the most important role of Ce on the NH3-SCR performance of MnOx-based catalysts has not been confirmed. Herein, the typical Ce-Mn/TiO2 catalyst was synthesized through incipient-wetness impregnation method, the positive role of Ce on Ce-Mn/TiO2 catalyst in the NH3-SCR process was revealed by combining different activity tests (including NO oxidation and NH3 oxidation) and characterizations (including XRD, XPS and He-TPDMS experiments). It was found that the introduction of Ce can promote the dispersion of MnOx on TiO2 support. Meanwhile, the doping of Ce in MnOx can also increase the content of Mn4+ species. The Mn4+ species plays a crucial role in NO oxidation reaction, which can trigger the “Fast SCR” reaction and promote the conversion of NOx. This work provides insight into the catalyst design for NH3-SCR process at low-temperature.

scholarly journals The Role of Impregnated Sodium Ions in Cu/SSZ-13 NH3-SCR Catalysts

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 593 ◽  
Author(s):  
Chen Wang ◽  
Jun Wang ◽  
Jianqiang Wang ◽  
Zhixin Wang ◽  
Zexiang Chen ◽  
...  
Keyword(s):  
Catalytic Reduction ◽  
Acid Sites ◽  
Particulate Filter ◽  
Kinetic Temperature ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Hydrothermal Aging ◽  
Scr Catalysts ◽  
Na Ions

To reveal the role of impregnated sodium (Na) ions in Cu/SSZ-13 catalysts, Cu/SSZ-13 catalysts with four Na-loading contents were prepared using an incipient wetness impregnation method and hydrothermally treated at 600 °C for 16 h. The physicochemical property and selective catalytic reduction (SCR) activity of these catalysts were studied to probe the deactivation mechanism. The impregnated Na exists as Na+ on catalysts and results in the loss of both Brönsted acid sites and Cu2+ ions. Moreover, the high loading of Na ions destroy the framework structure of Cu/SSZ-13 and forms new phases (SiO2/NaSiO3 and amorphous species) when Na loading was higher than 1.0 mmol/g. The decreased Cu2+ ions finally transformed into CuxO, CuO, and CuAlOx species. The inferior SCR activity of Na impregnated catalysts was mainly due to the reduced contents of Cu2+ ions at kinetic temperature region. The reduction in the amount of acid sites and Cu2+ ions, as well as copper oxide species (CuxO and CuO) formation, led to low SCR performance at high temperature. Our study also revealed that the existing problem of the Na ions’ effect should be well-considered, especially at high hydrothermal aging when diesel particulate filter (DPF) is applied in upstream of the SCR applications.

scholarly journals The Role of SO3 Poisoning in CU/SSZ-13 NH3-SCR Catalysts

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 741 ◽  
Author(s):  
Wang ◽  
Hou ◽  
Yan ◽  
Zhang ◽  
Wang ◽  
...  
Keyword(s):  
Copper Sulfate ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Copper Ions ◽  
Acid Resistance ◽  
Temperature Program Reduction ◽  
Copper Species ◽  
Nh3 Scr ◽  
Scr Catalysts

To reveal the role of SO3 poisoning in Cu/SSZ-13 NH3-SCR catalysts, fresh and sulfated Cu/SSZ-13 catalysts were prepared in the presence or absence of SO3 flux. The deactivation mechanism is probed by the changes of structural, copper species, and selective catalytic reduction (SCR) activity. The variations concentrate on the changes of copper species as the Chabazite (CHA) framework of Cu/SSZ-13 catalysts could keep intact at high ratios of SO3/SOx. The thermal gravimetric analyzer (TGA) results reveal that the copper sulfate formed during sulfation and the amounts of sulfate species increased with an increase in the SO3/SOx ratio. In contrast to the changing trend of copper sulfate, temperature program reduction (H2-TPR), and electron paramagnetic resonance (EPR) results manifest that, since the number of active copper ions declines with an increase of the SO3/SOx ratio, the active sites transform to these inactive species during sulfation. Due to the combination of NH3-SCR activity and the kinetic tests, it is shown that the decreased number of active sites is responsible for the declined SCR activity at low temperature. As Cu/SSZ-13 catalysts show excellent acid-resistance ability, our study reveals that the Cu/SSZ-13 catalyst is a good candidate for NOx elimination, especially when SO3 exists.

scholarly journals Simple physical mixing of zeolite prevents sulfur deactivation of vanadia catalysts for NOx removal

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Inhak Song ◽  
Hwangho Lee ◽  
Se Won Jeon ◽  
Ismail A. M. Ibrahim ◽  
Joonwoo Kim ◽  
...  
Keyword(s):  
Active Sites ◽  
Catalytic Reduction ◽  
Dew Point ◽  
Environmental Catalysis ◽  
Y Zeolite ◽  
Sulfur Resistance ◽  
Industrial Facilities ◽  
Physical Mixing ◽  
Sulfur Deactivation ◽  
Huge Challenge

AbstractNOx abatement has been an indispensable part of environmental catalysis for decades. Selective catalytic reduction with ammonia using V2O5/TiO2 is an important technology for removing NOx emitted from industrial facilities. However, it has been a huge challenge for the catalyst to operate at low temperatures, because ammonium bisulfate (ABS) forms and causes deactivation by blocking the pores of the catalyst. Here, we report that physically mixed H-Y zeolite effectively protects vanadium active sites by trapping ABS in micropores. The mixed catalysts operate stably at a low temperature of 220 °C, which is below the dew point of ABS. The sulfur resistance of this system is fully maintained during repeated aging/regeneration cycles because the trapped ABS easily decomposes at 350 °C. Further investigations reveal that the pore structure and the amount of framework Al determined the trapping ability of various zeolites.

scholarly journals The Key Role of pH Value in the Synthesis of Titanate Nanotubes-Loaded Manganese Oxides as a Superior Catalyst for the Selective Catalytic Reduction of NO with NH3

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xiongbo Chen ◽  
Chaoping Cen ◽  
Zhixiong Tang ◽  
Wenhao Zeng ◽  
Dingsheng Chen ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Surface Area ◽  
Manganese Oxides ◽  
Ph Value ◽  
Catalytic Reduction ◽  
Catalyst Support ◽  
Titanate Nanotubes ◽  
Scr Of No ◽  
Scr Catalysts

Titanate nanotubes (TNTs) synthesized by hydrothermal method were increasingly used as the catalyst support for the selective catalytic reduction (SCR) of NO with ammonia. This paper reports the critical process of postwashing to prepare satisfactory TNTs for the uses of SCR catalysts. Herein, alkaline TNTs (TNTs-AL), acidic TNTs (TNTs-AC), and neutral TNTs (TNTs-NE) were synthesized by controlling washing pH value. When these TNTs were utilized as the catalyst supports for manganese oxides (Mn/TNTs-AL, Mn/TNTs-AC, and Mn/TNTs-NE), the key role of pH value was found. Titanate nanosheets, titanate nanorods and titanate nanotubes were dominated in Mn/TNTs-AL, Mn/TNTs-AC, and Mn/TNTs-NE, respectively. MnO2crystal was observed when using TNTs-AC or TNTs-NE as the support. By contrast, Mn3O4and NaNO3were observed when using TNTs-AL as the support. Mn/TNTs-NE showed the best SCR activity, in line with the largest surface area, the best dispersion, and the most active redox property of manganese oxides. Mn/TNTs-AL showed negligible SCR activity, resulting from the minimum surface area, the Mn3O4-dominating crystal structure, and the bad dispersion of manganese oxides.

Are Three Items Sufficient to Measure Sense of Coherence?

2018 ◽  
Vol 34 (4) ◽  
pp. 229-237 ◽  
Author(s):  
Francesca Chiesi ◽  
Andrea Bonacchi ◽  
Caterina Primi ◽  
Alessandro Toccafondi ◽  
Guido Miccinesi
Keyword(s):  
Sense Of Coherence ◽  
Convergent Validity ◽  
Clinical Sample ◽  
Clinical Samples ◽  
Depression Symptoms ◽  
Time Saving ◽  
Positive Role ◽  
Patients With Cancer ◽  
Measure Sense

Abstract. The present study aimed at evaluating if the three-item sense of coherence (SOC) scale developed by Lundberg and Nystrom Peck (1995) can be effectively used for research purpose in both nonclinical and clinical samples. To provide evidence that it represents adequately the measured construct we tested its validity in a nonclinical (N = 658) and clinical sample (N = 764 patients with cancer). Results obtained in the nonclinical sample attested a positive relation of SOC – as measured by the three-item SOC scale – with Antonovsky’s 13-item and 29-item SOC scales (convergent validity), and with dispositional optimism, sense of mastery, anxiety, and depression symptoms (concurrent validity). Results obtained in the clinical sample confirmed the criterion validity of the scale attesting the positive role of SOC – as measured by the three-item SOC scale – on the person’s capacity to respond to illness and treatment. The current study provides evidence that the three-item SOC scale is a valid, low-loading, and time-saving instrument for research purposes on large sample.

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