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

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.

[1]  James E. Parks,et al.  Loading and Regeneration Analysis of a Diesel Particulate Filter with a Radio Frequency-Based Sensor , 2010 .

[2]  Ralf Moos,et al.  Microwave Cavity Perturbation Studies on H-form and Cu Ion-Exchanged SCR Catalyst Materials: Correlation of Ammonia Storage and Dielectric Properties , 2017, Topics in Catalysis.

[3]  William F Schneider,et al.  Isolation of the copper redox steps in the standard selective catalytic reduction on Cu-SSZ-13. , 2014, Angewandte Chemie.

[4]  J. Rumble.  CRC Handbook of Chemistry and Physics , 2019 .

[5]  Elisa Borfecchia,et al.  A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia , 2015 .

[6]  Ying Gao,et al.  Diesel Engine SCR Control: Current Development and Future Challenges , 2015, Emission Control Science and Technology.

[7]  Frank Willems,et al.  Ammonia sensor for closed-loop SCR control , 2008 .

[8]  Zhen Huang,et al.  Review of state of the art technologies of selective catalytic reduction of NOx from diesel engine exhaust , 2014 .

[9]  Christine Kay Lambert,et al.  Enhanced Durability of a Cu/Zeolite Based SCR Catalyst , 2008 .

[10]  Martin Votsmeier,et al.  Review on Radio Frequency Based Monitoring of SCR and Three Way Catalysts , 2016, Topics in Catalysis.

[11]  Harsha Nanjundaswamy,et al.  Advanced RF Particulate Filter Sensing and Controls for Efficient Aftertreatment Management and Reduced Fuel Consumption , 2015 .

[12]  Alexander Sappok,et al.  Radio Frequency Diesel Particulate Filter Soot and Ash Level Sensors: Enabling Adaptive Controls for Heavy-Duty Diesel Applications , 2014 .

[13]  T. Johnson.  Review of Vehicular Emissions Trends , 2015 .

[14]  Feng Gao,et al.  A comparative kinetics study between Cu/SSZ-13 and Fe/SSZ-13 SCR catalysts , 2015 .

[15]  Ralf Moos,et al.  Ammonia Loading Detection of Zeolite SCR Catalysts using a Radio Frequency based Method , 2015 .

[16]  Martin Votsmeier,et al.  Overview: Status of the Microwave-Based Automotive Catalyst State Diagnosis , 2013, Topics in Catalysis.

[17]  M. Elsener,et al.  Selective catalytic reduction of NO over commercial DeNOx-catalysts: experimental determination of kinetic and thermodynamic parameters , 1998 .

[18]  Martin Votsmeier,et al.  Effect of propene, propane, and methane on conversion and oxidation state of three-way catalysts: a microwave cavity perturbation study , 2015 .

[19]  Dieter Brüggemann,et al.  In-Operation Monitoring of the Soot Load of Diesel Particulate Filters: Initial Tests , 2013, Topics in Catalysis.

[20]  Ralf Moos,et al.  Determination of the NOx Loading of an Automotive Lean NOx Trap by Directly Monitoring the Electrical Properties of the Catalyst Material Itself , 2011, Sensors.

[21]  Pio Forzatti,et al.  Present status and perspectives in de-NOx SCR catalysis , 2001 .

[22]  Ralf Moos,et al.  The effect of Cu and Fe cations on NH3-supported proton transport in DeNOx-SCR zeolite catalysts , 2016 .

[23]  Anand Srinivasan,et al.  Development of a Kinetic Model to Evaluate Water Storage on Commercial Cu-Zeolite SCR Catalysts during Cold Start , 2017 .

[24]  Martin Votsmeier,et al.  Microwave Cavity Perturbation as a Tool for Laboratory In Situ Measurement of the Oxidation State of Three Way Catalysts , 2013, Topics in Catalysis.

[25]  Martin Elsener,et al.  NOx-Reduction in Diesel Exhaust Gas with Urea and Selective Catalytic Reduction , 1996 .

[26]  Frerich J. Keil,et al.  Theoretical Investigation of the Mechanism of the Selective Catalytic Reduction of Nitric Oxide with Ammonia on H-Form Zeolites , 2008 .

[27]  Ralf Moos,et al.  Microwave-Based Oxidation State and Soot Loading Determination on Gasoline Particulate Filters with Three-Way Catalyst Coating for Homogenously Operated Gasoline Engines , 2015, Sensors.

[28]  Ralf Moos,et al.  Correlating the Integral Sensing Properties of Zeolites with Molecular Processes by Combining Broadband Impedance and DRIFT Spectroscopy—A New Approach for Bridging the Scales , 2015, Sensors.

[29]  M. Elsener,et al.  Urea-SCR: a promising technique to reduce NOx emissions from automotive diesel engines , 2000 .

[30]  Ralf Moos,et al.  Detection of the ammonia loading of a Cu Chabazite SCR catalyst by a radio frequency-based method , 2014 .

[31]  Ralf Moos,et al.  Microwave-Based Catalyst State Diagnosis - State of the Art and Future Perspectives , 2015 .

[32]  Gunter Hagen,et al.  Monitoring the Ammonia Loading of Zeolite‐Based Ammonia SCR Catalysts by a Microwave Method , 2011 .

[33]  Yann Creff,et al.  About Cross-Sensitivities of NOx Sensors in SCR Operation , 2013 .

[34]  Gunter Hagen,et al.  Radio-Frequency-Based Urea Dosing Control for Diesel Engines with Ammonia SCR Catalysts , 2017 .

[35]  A. V. Soldatov,et al.  Revisiting the nature of Cu sites in the activated Cu-SSZ-13 catalyst for SCR reaction† †Electronic supplementary information (ESI) available: experimental section (sample description, in situ FTIR spectroscopy, synchrotron characterization, DFT-based analysis of XAS and XES data); XAS of hydrated C , 2014, Chemical science.

[36]  Andreas Müller,et al.  Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts , 2017, Sensors.

[37]  Daniel Heß,et al.  Simulationsgestützte Robustheitsanalyse von On-Board-Diagnosefunktionen , 2016 .

[38]  Ralf Moos,et al.  A microwave-based method to monitor the ammonia loading of a vanadia-based SCR catalyst , 2015 .

[39]  Ralf Moos,et al.  A Laboratory Test Setup for in Situ Measurements of the Dielectric Properties of Catalyst Powder Samples under Reaction Conditions by Microwave Cavity Perturbation: Set up and Initial Tests , 2014, Sensors.

[40]  Neal W. Currier,et al.  Effect of Transition Metal Ion Properties on the Catalytic Functions and Sulfation Behavior of Zeolite-Based SCR Catalysts , 2017 .

[41]  Fengjun Yan,et al.  Detection of Injected Urea Quantity and Correction for SCR Urea Dosing Control , 2015 .

[42]  Martin Votsmeier,et al.  In operando Detection of Three-Way Catalyst Aging by a Microwave-Based Method: Initial Studies , 2015 .

[43]  Ralf Moos,et al.  Automotive Catalyst State Diagnosis Using Microwaves , 2015 .

[44]  Ralf Moos,et al.  Ammonia storage studies on H-ZSM-5 zeolites by microwave cavity perturbation: correlation of dielectric properties with ammonia storage , 2015 .

[45]  Yisun Cheng,et al.  Laboratory Testing of Urea-SCR Formulations to Meet Tier 2 Bin 5 Emissions , 2007 .

[46]  Tan Feng,et al.  The characteristics of ammonia storage and the development of model-based control for diesel engine urea-SCR system , 2015 .