Suppression of N2O formation by H2O and SO2 in the selective catalytic reduction of NO with NH3 over a Mn/Ti–Si catalyst

2019 ◽  
Vol 9 (17) ◽  
pp. 4759-4770 ◽  
Author(s):  
Bolin Zhang ◽  
Michael Liebau ◽  
Wladimir Suprun ◽  
Bo Liu ◽  
Shengen Zhang ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Lewis Acid ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
N2o Formation ◽  
Brønsted Acid Sites ◽  
Reduction Of No ◽  
Suppression Effects

Proposed mechanism of NO reduction and N2O formation as well as H2O/SO2 suppression effects with participation of (a) Lewis acid sites and (b) Brønsted acid sites over a Mn/Ti–Si catalyst.

Mechanistic insight into the influence of O2 on N2O formation in the selective catalytic reduction of NO with NH3 over Pd/CeO2 catalyst

2021 ◽  
Author(s):  
Liping Sheng ◽  
Songda Li ◽  
Zhaoxia Ma ◽  
Fei Wang ◽  
Hu He ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Temperature Dependent ◽  
N2o Formation ◽  
Reduction Of No ◽  
Mechanistic Insight ◽  
Insight Into

O2 greatly affected the pathway for NO reduction over the Pd/CeO2 catalyst and resulted in a temperature-dependent NH3-SCR performance and formation of N2O.

scholarly journals Preparation of Mesoporous Mn–Ce–Ti–O Aerogels by a One-Pot Sol–Gel Method for Selective Catalytic Reduction of NO with NH3

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 475
Author(s):  
Yabin Wei ◽  
Shuangling Jin ◽  
Rui Zhang ◽  
Weifeng Li ◽  
Jiangcan Wang ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Lewis Acid ◽  
Catalytic Reduction ◽  
Sol Gel ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
One Pot ◽  
Gel Method ◽  
Nh3 Scr ◽  
Composite Aerogels

Novel Mn–Ce–Ti–O composite aerogels with large mesopore size were prepared via a one-pot sol–gel method by using propylene oxide as a network gel inducer and ethyl acetoacetate as a complexing agent. The effect of calcination temperature (400, 500, 600, and 700 °C) on the NH3–selective catalytic reduction (SCR) performance of the obtained Mn–Ce–Ti–O composite aerogels was investigated. The results show that the Mn–Ce–Ti–O catalyst calcined at 600 °C exhibits the highest NH3–SCR activity and lowest apparent activation energy due to its most abundant Lewis acid sites and best reducibility. The NO conversion of the MCTO-600 catalyst maintains 100% at 200 °C in the presence of 100 ppm SO2, showing the superior resistance to SO2 poisoning as compared with the MnOx–CeO2–TiO2 catalysts reported the literature. This should be mainly attributed to its large mesopore sizes with an average pore size of 32 nm and abundant Lewis acid sites. The former fact facilitates the decomposition of NH4HSO4, and the latter fact reduces vapor pressure of NH3. The NH3–SCR process on the MCTO-600 catalyst follows both the Eley–Rideal (E–R) mechanism and the Langmuir–Hinshelwood (L–H) mechanism.

scholarly journals Effect of the calcination temperature of cerium–zirconium mixed oxides on the structure and catalytic performance of WO3/CeZrO2 monolithic catalyst for selective catalytic reduction of NOx with NH3

RSC Advances ◽  
2017 ◽  
Vol 7 (39) ◽  
pp. 24177-24187 ◽  
Author(s):  
Haidi Xu ◽  
Mengmeng Sun ◽  
Shuang Liu ◽  
Yuanshan Li ◽  
Jianli Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Lewis Acid ◽  
Mixed Oxides ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Reduction Of Nox ◽  
Calcined Temperature

The calcined temperature of the carrier obviously affected SCR activity of catalysts, WO3/Ce0.68Zr0.32O2-500 showed the best low-temperature NH3-SCR activity due to its more Lewis acid sites and stronger redox property.

Efficiency of Phosphotungstic Acid Modified Mn-Based Catalysts to Promote Activity and N2 Formation for Selective Catalytic Reduction of NO with Ammonia

2019 ◽  
Vol 17 (7) ◽  
Author(s):  
Yongqiang Huang ◽  
Peixin Li ◽  
Runduo Zhang ◽  
Ying Wei
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
No Conversion ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Nitrate Species

Abstract In this work, the modified Mn-based NH3-SCR (NH3 low-temperature selective catalytic reduction) catalysts with excellent NO conversion and N2 selectivity be designed. N2 yield was hardly more than 75 % over MnOx/TiO2 for NH3-SCR reaction, whereas the NH3-SCR performance has been significantly improved by using 50 wt.% HPW (H3PW12O40)-MnOx/TiO2. 100 % NO conversion and more than 95 % N2 yield was obtained in wide operating temperature window (150–400°C), suggesting that the addition of HPW could effectively improve the NO reduction conversion. After that, the catalysts were further characterized by XRD, H2-TPR, XPS and in situ DRIFT. DRIFT analysis implied that the introduction of HPW significantly improve the capacity of NH4 + species adsorbed on Brønsted acid sites accompanied with inhibiting the formation and consumption of nitrite species. It proved that the non-selective catalytic reduction reaction over HPW-MnOx/TiO2 catalysts are restrained. HPW could accelerate the formation and consumption of NH4 + species adsorbed on Brønsted acid sites with deactivation of nitrate species. In addition, NH3(ad) could be hardly oxidized to NH species and then reacted with nitrate species (L-H mechanism) and gaseous NO (E-R mechanism). More importantly, the oxidation of NH3 was also suppressed, which plays a dominate role to form N2O above 300°C. Besides, the deactivation of potassium poisoning on the SCR activity significantly weakened for modified samples compared to parent catalyst.

scholarly journals Insights into the promotion role of phosphorus doping on carbon as a metal-free catalyst for low-temperature selective catalytic reduction of NO with NH3

RSC Advances ◽  
2020 ◽  
Vol 10 (22) ◽  
pp. 12908-12919
Author(s):  
Weifeng Li ◽  
Shuangling Jin ◽  
Rui Zhang ◽  
Yabin Wei ◽  
Jiangcan Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
No Reduction ◽  
Catalytic Reduction ◽  
Carbon Aerogels ◽  
Phosphorus Doping ◽  
Reduction Of No ◽  
Metal Free

P species can effectively enhance the catalytic activity of carbon aerogels for NO reduction at low temperature.

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