scholarly journals Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

Sensors ◽  
2017 ◽  
Vol 17 (7) ◽  
pp. 1615 ◽  
Author(s):  
Markus Dietrich ◽  
Gunter Hagen ◽  
Willibald Reitmeier ◽  
Katharina Burger ◽  
Markus Hien ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Selective Catalytic Reduction ◽  
New Technologies ◽  
Catalytic Reduction ◽  
Special Focus ◽  
Temperature Range ◽  
Scr Catalysts ◽  
Rf Signals ◽  
High Space ◽  
First Time

The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

A Ce-Zr-Ti Oxide Catalyst for Selective Catalytic Reduction of NO with Ammonia

2014 ◽  
Vol 535 ◽  
pp. 709-712
Author(s):  
Ye Jiang ◽  
Yan Yan ◽  
Shan Bo Huang ◽  
Xiong Zhang ◽  
Xin Wei Wang ◽  
...  
Keyword(s):  
High Activity ◽  
Selective Catalytic Reduction ◽  
Oxide Catalyst ◽  
Catalytic Reduction ◽  
Space Velocity ◽  
Impregnation Method ◽  
Reduction Of No ◽  
No Conversion ◽  
Temperature Range ◽  
Ti Oxides

A Ce-Zr-Ti oxide catalyst was prepared by an impregnation method and tested for the selective catalytic reduction of NO with NH3. The Ce-Zr-Ti oxide catalyst exhibited high activity and more than 95% NO conversion was obtained within the temperature range 300-500 °C at the high gas hourly space velocity of 50,000 h-1. The addition of Zr improved the activity of Ce-Ti oxides especially at higher reaction temperatures and their resistance to SO2.

scholarly journals A review of Mn-containing oxide catalysts for low temperature selective catalytic reduction of NOx with NH3: reaction mechanism and catalyst deactivation

RSC Advances ◽  
2017 ◽  
Vol 7 (42) ◽  
pp. 26226-26242 ◽  
Author(s):  
Shengen Zhang ◽  
Bolin Zhang ◽  
Bo Liu ◽  
Shuailing Sun
Keyword(s):  
Reaction Mechanism ◽  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Catalyst Deactivation ◽  
Catalytic Reduction ◽  
Oxide Catalysts ◽  
Scr Catalysts ◽  
Reduction Of Nox

The reactions over Mn-containing selective catalytic reduction (SCR) 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...

Selective Catalytic Reduction of NO x with Ammonia over Copper Ion Exchanged SAPO-47 Zeolites in a Wide Temperature Range

ChemCatChem ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 2481-2487 ◽  
Author(s):  
Yani Zhang ◽  
Yue Peng ◽  
Chizhong Wang ◽  
Kezhi Li ◽  
Shuai Liu ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Wide Temperature Range ◽  
Catalytic Reduction ◽  
Copper Ion ◽  
Reduction Of No ◽  
Temperature Range

Iron-exchanged high-silica LTA zeolites as hydrothermally stable NH3-SCR catalysts

2019 ◽  
Vol 4 (6) ◽  
pp. 1050-1058 ◽  
Author(s):  
Taekyung Ryu ◽  
Yonjoo Kang ◽  
In-Sik Nam ◽  
Suk Bong Hong
Keyword(s):  
High Activity ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Hydrothermal Aging ◽  
Reduction Of No ◽  
Nh3 Scr ◽  
Scr Catalysts ◽  
High Silica

Iron-exchanged high-silica LTA zeolites exhibit high activity for selective catalytic reduction of NOx by NH3, even after hydrothermal aging at 900 °C.

scholarly journals Direct Simultaneous Measurement of Particulate Matter and Ammonia Storage on Combined Selective Catalytic Reduction Filter Systems Using Radio Frequency Sensors

2018 ◽  
Author(s):  
Paul A. Ragaller ◽  
Alexander Sappok ◽  
Jie Qiao ◽  
Xiaojin Liu ◽  
Jonathan Aguilar
Keyword(s):  
Particulate Matter ◽  
Radio Frequency ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Particulate Filter ◽  
Practical Implementation ◽  
Simultaneous Measurements ◽  
Soot Loading ◽  
Rf Spectrum

Tightening global emissions regulations are motivating interest in the development and implementation of Selective Catalytic Reduction + Filtration (SCRF) systems, which are designed to reduce the concentration of tailpipe particulate matter (PM) and NOx emissions. These systems allow designers to combine the NOx reduction capability of an SCR with the filtration capability of a particulate filter on a single unit. Practical implementation of these systems requires reliable measurement and diagnosis of their state — both with respect to trapped particulate matter as well as adsorbed ammonia. Currently, these systems rely on a variety of gas sensors, mounted upstream or downstream of the system, that only provide an indirect inference of the operation state. In this study, a single radio frequency (RF) sensor was used to perform simultaneous measurements of soot loading and ammonia inventory on an SCRF. Several SCRF core samples were tested at varying soot and ash loads in a catalyst reactor bench. Soot levels were measured by monitoring changes in the bulk dielectric properties within the catalyst using the sensor, while ammonia levels were determined by feeding selected regions of the RF spectrum into a pretrained generalized regression neural network model. Results show the RF sensor is able to directly measure the instantaneous ammonia inventory, while simultaneously providing soot loading measurements within 0.5 g/L. These results confirm that simultaneous measurements of both the PM and ammonia loading state of an SCRF are possible using a single RF sensor via analysis of specific features in the full RF spectrum. The results indicate significant potential to remove the control barriers typically associated with the implementation of advanced SCRF systems.

scholarly journals Performance of Mn-Fe-Ce/GO-x for Catalytic Oxidation of Hg0 and Selective Catalytic Reduction of NOx in the Same Temperature Range

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 399 ◽  
Author(s):  
Donghai An ◽  
Xiaoyang Zhang ◽  
Xingxing Cheng ◽  
Yong Dong
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Oxidation ◽  
Flue Gas ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Good Mechanical Property ◽  
Active Components ◽  
Thermal Methods ◽  
Temperature Range ◽  
Reduction Of Nox

A series of composites of Mn-Fe-Ce/GO-x have been synthesized by a hydrothermal method. Their performance in simultaneously performing the catalytic oxidation of Hg0 and the selective catalytic reduction of nitrogen oxides (NOx) in the same temperature range were investigated. In order to investigate the physicochemical properties and surface reaction, basic tests, including Brunauer-Emmett-Teller (BET), XRD, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) were selected. The results indicate that the active components deposited on graphene play an important role in the removal of mercury and NOx, with different valences. Especially, the catalyst of Mn-Fe-Ce/GO-20% possesses an excellent efficiency in the temperature range of 170 to 250 °C. Graphene has a huge specific surface area and good mechanical property; thus, the active components of the Mn-Fe-Ce catalyst can be highly dispersed on the surface of graphene oxide. In addition, the effects of O2, H2O, NO and SO2 on the removal efficiency of Hg0 were examined in flue gas. Furthermore, the regeneration experiments conducted by thermal methods proved to be promising methods.

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