On the influence of the NO equilibrium reaction on mixed potential sensor signals: A comparison between FE modelling and experimental data

Abstract The detection of NOx in automotive exhaust gas is a challenge for electrochemical gas sensors. In most cases, measuring systems are unsuitable to distinguish between NO and NO2. Mixed potential sensors can theoretically determine with sufficient selectivity NO or NO2. One issue to be considered is that heterogeneous catalysis brings the NOx mixtures partly into the thermodynamic equilibrium. Therefore, the influence of this NOx conversion is investigated in this paper. For this purpose, an FE model for mixed potential sensors is used to verify whether the NOx equilibrium must be taken into account in order to simulate the sensor behavior in the measurements. It is explained how the necessary parameters for the model are quantified. It is shown that the sensor behavior can be reproduced without considering the equilibrium if NO or NO2 is dosed alone. In the NO/NO2 mixture, on the other hand, it is no longer possible for a model without NOx equilibrium to agree with the experimental data. Only when considering the heterogeneously catalyzed NOx conversion, it is possible to explain numerically the measured data with astonishing agreement. Furthermore, the resulting data set can be used for other electrode geometries without having to characterize them electrochemically again.

[1]  N. Shikazono,et al.  Evaluation of SOFC anode polarization simulation using three-dimensional microstructures reconstructed by FIB tomography , 2011 .

[2]  K. Zaghib,et al.  Quantifying tortuosity in porous Li-ion battery materials , 2009 .

[3]  L. Gauckler,et al.  Identification of the reaction mechanism of the Pt, O2(g)|yttria-stabilized zirconia system: Part II: Model implementation, parameter estimation, and validation , 1999 .

[4]  V. Balakotaiah,et al.  Experimental and kinetic study of NO oxidation on model Pt catalysts , 2009 .

[5]  G. Lu,et al.  Mixed-potential-type NO2 sensors based on stabilized zirconia and CeO2-B2O3 (B = Fe, Cr) binary nanocomposites sensing electrodes , 2018, Sensors and Actuators B: Chemical.

[6]  Jing Wang,et al.  Novel Zn–M–O (M = Sn, Co) sensing electrodes for selective mixed potential CO/C3H8 sensors , 2013 .

[7]  C. Wilke,et al.  Diffusion Coefficients in Multicomponent Gas Mixtures , 1950 .

[8]  G. Lu,et al.  Stabilized zirconia-based mixed potential type sensors utilizing MnNb2O6 sensing electrode for detection of low-concentration SO2 , 2017 .

[9]  Y. Tan.  Heterogeneous Electrode Processes and Localized Corrosion , 2012 .

[10]  R. J. Millington,et al.  Gas Diffusion in Porous Media , 1959, Science.

[11]  Sun-Ju Song,et al.  Influence of sintering temperature on the physical, electrochemical and sensing properties of α-Fe2O3-SnO2 nanocomposite sensing electrode for a mixed-potential type NOx sensor , 2019, Ceramics International.

[12]  Norio Miura,et al.  Mixed-potential-type NOx sensor based on YSZ and zinc oxide sensing electrode , 2004 .

[13]  C. Myung,et al.  Comparative investigation of NOx emission characteristics from a Euro 6-compliant diesel passenger car over the NEDC and WLTC at various ambient temperatures , 2017 .

[14]  Y. Shimizu,et al.  Effects of composition and structure of sensing electrode on NO2 sensing properties of mixed potential-type YSZ-based gas sensors , 2016 .

[15]  Gunter Hagen,et al.  Solid state mixed-potential sensors as direct conversion sensors for automotive catalysts , 2018 .

[16]  Johann Riegel,et al.  Exhaust gas sensors for automotive emission control , 2002 .

[17]  Ralf Moos,et al.  Pulsed Polarization-Based NOx Sensors of YSZ Films Produced by the Aerosol Deposition Method and by Screen-Printing , 2017, Sensors.

[18]  Chonghoon Lee,et al.  Sensing behavior and mechanism of mixed potential NOx sensors using NiO, NiO(+YSZ) and CuO oxide electrodes , 2009 .

[19]  B. R. Baliga,et al.  A NEW FINITE-ELEMENT FORMULATION FOR CONVECTION-DIFFUSION PROBLEMS , 1980 .

[20]  Zhangxin Chen,et al.  Critical review of the impact of tortuosity on diffusion , 2007 .

[21]  Maximilian Fleischer,et al.  Method for detection of NOx in exhaust gases by pulsed discharge measurements using standard zirconia-based lambda sensors , 2010 .

[22]  Keith B. Oldham,et al.  Electrochemical Science and Technology: Fundamentals and Applications , 2011 .

[23]  G. Lu,et al.  High performance mixed-potential type NO2 sensors based on three-dimensional TPB and Co3V2O8 sensing electrode , 2015 .

[24]  N. Padture,et al.  Thermal conductivity of dense and porous yttria-stabilized zirconia , 2001 .

[25]  C. H. Bamford,et al.  Electrode Kinetics: Principles and Methodology , 1986 .

[26]  Robert S. Brodkey,et al.  Transport Phenomena: A Unified Approach , 2003 .

[27]  N. Yamazoe,et al.  Mixed Potential Hydrogen Sensor Combining Oxide Ion Conductor with Oxide Electrode , 1996 .

[28]  Norio Miura,et al.  High-temperature sensors for NO and NO2 based onstabilized zirconiaand spinel-type oxide electrodes , 1997 .

[29]  R. Moos,et al.  Effect of the Heterogeneous Catalytic Activity of Electrodes for Mixed Potential Sensors , 2018 .

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

[31]  N. Miura,et al.  Sensing Characteristics of YSZ-Based Mixed-Potential-Type Planar NO x Sensors Using NiO Sensing Electrodes Sintered at Different Temperatures , 2005 .

[32]  M. Verbrugge,et al.  Mathematical model of a gas diffusion electrode bonded to a polymer electrolyte , 1991 .

[33]  R. Reid,et al.  The Properties of Gases and Liquids , 1977 .

[34]  Carsten Korte,et al.  Electrochemical blackening of yttria-stabilized zirconia – morphological instability of the moving reaction front , 1999 .

[35]  I. Mills,et al.  Quantities, Units and Symbols in Physical Chemistry , 1993 .

[36]  Franz Schubert,et al.  Self-heated HTCC-based ceramic disc for mixed potential sensors and for direct conversion sensors for automotive catalysts , 2017 .

[37]  J. A. A. Tillaart,et al.  Improved SCR Systems for Heavy Duty Applications , 2000 .

[38]  Gunter Hagen,et al.  A finite element model for mixed potential sensors , 2019, Sensors and Actuators B: Chemical.

[39]  Biao Wang,et al.  Highly sensitive mixed-potential-type NO2 sensor with YSZ processed using femtosecond laser direct writing technology , 2014 .

[40]  N. Miura,et al.  Construction of sensitive and selective zirconia-based CO sensors using ZnCr2O(4)-based sensing electrodes. , 2012, Langmuir : the ACS journal of surfaces and colloids.