scholarly journals Non-thermal-plasma-activated de-NO x catalysis

2017 ◽  
Vol 376 (2110) ◽  
pp. 20170054 ◽  
Author(s):  
Rahman Gholami ◽  
Cristina E. Stere ◽  
Alexandre Goguet ◽  
Christopher Hardacre
Keyword(s):  
Adsorption Capacity ◽  
Selective Catalytic Reduction ◽  
Thermal Plasma ◽  
Catalytic Reduction ◽  
Lean Burn ◽  
Reduction Activity ◽  
Reduction Efficiency ◽  
Non Thermal Plasma ◽  
The Rich ◽  
Catalyst Systems

The combination of non-thermal plasma (NTP) with catalyst systems as an alternative technology to remove NO x emissions in the exhaust of lean-burn stationary and mobile sources is reviewed. Several factors, such as low exhaust gas temperatures (below 300°C), low selectivity to N 2 and the presence of impurities, make current thermally activated technologies inefficient. Various hybrid plasma–catalyst systems have been examined and shown to have a synergistic effect on de-NO x efficiency when compared with NTP or catalyst-alone systems. The NTP is believed to form oxygenated species, such as aldehydes and nitrogen-containing organic species, and to convert NO to NO 2 , which improves the reduction efficiency of N 2 during hydrocarbon-selective catalytic reduction reactions. The NTP has been used as a pretreatment to convert NO to its higher oxidation states such as NO 2 to improve NO x reduction efficiency in the subsequent processes, e.g. NH 3 -selective catalytic reduction. It has been applied to the lean phase of the NO x storage to improve the adsorption capacity of the catalyst by conversion of NO to NO 2 . Alternatively, a catalyst with high adsorption capacity is chosen and the NTP is applied to the rich phase to improve the reduction activity of the catalyst at low temperature. This article is part of a discussion meeting issue ‘Providing sustainable catalytic solutions for a rapidly changing world’.

scholarly journals Selective Catalytic Reduction of NO by NH3 Using a Combination of Non-Thermal Plasma and Mn-Cu/ZSM5 Catalyst

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1044
Author(s):  
Tao Zhu ◽  
Xing Zhang ◽  
Wenfeng Niu ◽  
Yatao Liu ◽  
Bo Yuan ◽  
...  
Keyword(s):  
Energy Density ◽  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Removal Efficiency ◽  
Thermal Plasma ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
High Energy ◽  
No Removal ◽  
Non Thermal Plasma

Dielectric barrier discharge (DBD) could generate non-thermal plasma (NTP) with the advantage of fast reactivity and high energy under atmosphere pressure and low-temperature. The presented work investigated the selective catalytic reduction (SCR) of nitric oxide (NO) using a combination of NTP and an Mn-Cu/ZSM5 catalyst with ammonia (NH3) as a reductant. The experimental results illustrate that the plasma-assisted SCR process enhances the low-temperature catalytic performance of the Mn-Cu/ZSM5 catalyst significantly, and it exhibits an obvious improvement in the NO removal efficiency. The reaction temperature is maintained at 200 °C in order to simulate the exhaust temperature of diesel engine, and the 10% Mn-8% Cu/ZSM5 catalyst shows the highest NO removal performance with about 93.89% at an energy density of 500 J L−1 and the selectivity to N2 is almost 99%. The voltage, frequency and energy density have a positive correlation to NO removal efficiency, which is positively correlated with the power of NTP system. In contrast, the O2 concentration has a negative correlation to the NO removal, and the NO removal efficiency cannot be improved when the NO removal process reaches reaction equilibrium in the NTP system.

Experimental and kinetic analysis of hydrothermal aging effects on ammonia adsorption capacity over a commercial Cu-zeolite selective catalytic reduction catalyst

2018 ◽  
Vol 233 (12) ◽  
pp. 3030-3042
Author(s):  
Tae Joong Wang ◽  
In Hyuk Im
Keyword(s):  
Adsorption Capacity ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Adsorption Site ◽  
Selective Catalytic Reduction Catalyst ◽  
Aging Effects ◽  
Hydrothermal Aging ◽  
Ammonia Adsorption ◽  
Fresh Catalyst ◽  
Reduction Catalysts

Ammonia/urea selective catalytic reduction is an efficient technology to control NOx emission from diesel engines. One of its critical challenges is the performance degradation of selective catalytic reduction catalysts due to the hydrothermal aging experienced in real-world operations during the lifetime. In this study, hydrothermal aging effects on the reduction of ammonia adsorption capacity over a commercial Cu-zeolite selective catalytic reduction catalyst were investigated under actual engine exhaust conditions. Ammonia adsorption site densities of the selective catalytic reduction catalysts aged at two different temperatures of 750°C and 850°C for 25 h with 10% H2O were experimentally measured and compared to that of fresh catalyst on a dynamometer test bench with a heavy-duty diesel engine. The test results revealed that hydrothermal aging significantly decreased the ammonia adsorption capacity of the current commercial Cu-zeolite selective catalytic reduction catalyst. Hydrothermal treatment at 750°C reduced the ammonia adsorption site to 62.5% level of that of fresh catalyst, while hydrothermal treatment at 850°C lowered the adsorption site to 37.0% level of that of fresh catalyst. Also, in this study, numerical simulation and kinetic analysis were carried out to quantify the impact of hydrothermal aging on the reduction of ammonia adsorption capacity by introducing an aging coefficient. The kinetic parameter calibrations based on actual diesel engine tests with a commercial monolith Cu-zeolite selective catalytic reduction catalyst provided a highly realistic kinetic parameter set of ammonia adsorption/desorption and enabled a mathematical description of hydrothermal aging effect.

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