Application of V2O5/WO3/TiO2 for Resistive-Type SO2 Sensors

Izu, Noriya; Hagen, Gunter; Schönauer, Daniela; Röder-Roith, Ulla; Moos, Ralf

doi:10.3390/s110302982

Cited by 55 publications

(28 citation statements)

References 24 publications

(33 reference statements)

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“…It was found that at higher concentration, the relation between SO 2 concentration to the first discriminant function was not linear anymore, but more exponential. This observation that the linear correlation changed into exponential at high SO 2 concentrations appeared to agree with some previous studies on other SO 2 sensors [25,26]. However, in some groups, it was observed that the increase was very sharp at higher concentrations.…”

Section: Performance Test In Desulphurization Pilot Plant Unitsupporting

confidence: 79%

Hierarchical methods to improve the performance of the SiC-FET as SO2 sensors in flue gas desulphurization systems

Darmastuti

Bur

Lindqvist

et al. 2015

Sensors and Actuators B: Chemical

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Experiments were performed both in the laboratory and a desulfurization pilot unit in order to improve the SiC-FET sensor performance using two-step data evaluation. In both cases, a porous Pt-gate enhancement type SiC-FET was utilized in a temperature cycled operation (TCO). Liner Discriminant Analysis (LDA) was chosen as the method for multivariate data analysis. Hierarchical methods with two-step LDA worked quite well in the laboratory tests with SO 2 concentrations varied from 25-200 ppm. The same data evaluation was also applied to tests in the desulfurization pilot unit, with higher gas flow and a larger SO 2 concentration range (up to 5000 ppm). The results from the SO 2 quantification showed a significantly improved fit to corresponding reference instrument (FTIR) values. 2 IntroductionSO 2 has a significant impact on human health and the environment due to its ability to cause acid rain and form acid particulates. The majority of the emission comes from the energy sector [1]. The European Environmental Agency (EEA) has reported that in the last decade the SO 2 emission has decreased by about 74% and the majority of the reduction has come from power generation and distribution (58%) [2]. The EEA also stated [2] that the reduction in SO 2 has been the result of use of fuels with lower sulfur content and the increase in efficiency of desulfurization systems. However, these measures are not sufficient. The goal for future SO 2 emission reduction has been outlined according to stricter regulation. One way to achieve this goal is to improve the efficiency of the sulfur removal unit even more.In thermal power plants, SO 2 is produced as an unwanted by-product from the combustion of sulfur containing fuel, and it needs to be removed before venting the flue gas to the atmosphere. SO 2 is removed in a desulfurization system. Lime (Ca(OH) 2 ) is mixed with ash and injected into the dry desulfurization system to react with SO 2 in the gas phase. The resulting products are separated from the flue gas by a fabric filter before venting the flue gas to the atmosphere [3]. In this process, sensors play an important role, not only in detecting the concentration of SO 2 at the outlet of the unit, but also in monitoring the concentration profile throughout the duct. The latter application is important for maintaining concentration uniformity of the flue gas, and thus, for improving the efficiency of the desulfurization unit.SiC based sensors are suitable candidates for the desulfurization application due to the inert behavior of SiC in high temperature, oxidizing environments [4][5][6]. Moreover, SiC-FET sensors have shown promising results in industrial environments for CO [7,8] and NH 3 [6,9].The sensors are based on commercial transistor devices with porous catalytic metal gate on top of the gate oxide [4]. The target gas is adsorbed, and then decomposed upon interaction with oxygen ions on the catalytic metal surface. The interaction between the target gases and the metal surface changes the balance of the surf...

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Section: Performance Test In Desulphurization Pilot Plant Unitsupporting

confidence: 79%

Hierarchical methods to improve the performance of the SiC-FET as SO2 sensors in flue gas desulphurization systems

Darmastuti

Bur

Lindqvist

et al. 2015

Sensors and Actuators B: Chemical

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“…Previous studies on Au-based sensors [3,27] have also demonstrated the potential of Au as sensing layer for SO 2 sensors. For all three catalytic metals, it was possible to determine the presence of SO 2 with normal static operation.…”

Section: Static Operationmentioning

confidence: 99%

“…Liquid electrochemical cells cannot operate in high humidity and high temperature conditions [1]. Metal oxide sensors usually are not the best choice in environments with low and changing concentration of oxygen [2,3]. Optical detection such as FTIR is relatively more expensive than chemical sensors [4].…”

Section: Introductionmentioning

confidence: 99%

SiC–FET based SO2 sensor for power plant emission applications

Darmastuti

Bur

Möller

et al. 2014

Sensors and Actuators B: Chemical

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Thermal power plants produce SO 2 during combustion of fuel containing sulfur. One way to decrease the SO 2 emission from power plants is to introduce a sensor as part of the control system of the desulphurization unit. In this study, SiC-FET sensors were studied as one alternative sensor to replace the expensive FTIR (Fourier Transform Infrared) instrument or the inconvenient wet chemical methods. The gas response for the SiC-FET sensors comes from the interaction between the test gas and the catalytic gate metal, which changes the electrical characteristics of the devices. The performance of the sensors depends on the ability of the test gas to be adsorbed, decomposed, and desorbed at the sensor surface. The feature of SO 2 , that it is difficult to desorb from the catalyst surface, makes it known as catalyst poison.It is difficult to quantify the SO 2 with static operation, even at the optimum operation temperature of the sensor due to low response levels and saturation already at low concentration of SO 2 . The challenge of SO 2 desorption can be reduced by introducing dynamic operation in a designed temperature cycle operation (TCO). The intermittent exposure to high temperature can help to desorb SO 2 . Simultaneously, additional features extracted from the sensor data can be used to reduce the influence of sensor drift. The TCO operation, together with pattern recognition, may also reduce the baseline and response variation due to changing concentration of background gases (4-10% O 2 and 0-70% RH), and thus it may improve the overall sensor performance. In addition to the laboratory experiment, testing in the desulphurization pilot unit was performed. Desulphurization pilot unit has less controlled environment compared to the laboratory conditions. Therefore, the risk of influence from the changing concentration of background gas is higher. In this study, Linear Discriminant Analysis (LDA) and Partial Least Square (PLS) were employed as pattern recognition methods. It was demonstrated that using LDA quantification of SO 2 into several groups of concentrations up to 2000 ppm was possible. Additionally, PLS analysis indicated a good agreement between the predicted value from the model and the SO 2 concentration from the reference instrument of the pilot plant. 3 IntroductionSO 2 is one of the major air pollutants because it is a precursor of acid rain, forms acid particulates, and is dangerous for human health. However, in a thermal power plant, SO 2 is generally produced when sulfur containing fuel is combusted. In flue gas cleaning processes, SO 2 is usually removed by absorption with lime (CaOH 2 .2H 2 O) or other compounds having high alkalinity. State-of-the-art desulphurization can remove more than 98% of the SO 2 from the flue gas. With increasing environmental concerns, the regulation of SO 2 emission from thermal power plants has become stricter. The installation of sensors in the flue gas duct has been proposed as one of the alternatives to improve the efficiency of the desulphurization un...

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“…6)9) To the best of our knowledge, there are only a few papers reporting on SO 2 19) In this study, we varied the vanadium oxide concentration between 1.5 and 3.0 wt % and the electrode materials between Pt and Au and measured the potential changes when exposed to SO 2 and/or other gases in detail. As a result, it was found out that for the SO 2 response the electrode materials play a more crucial role.…”

Section: Introductionmentioning

confidence: 99%

Planar potentiometric SO2 gas sensor for high temperatures using NASICON electrolyte combined with V2O5/WO3/TiO2 + Au or Pt electrode

Izu

Hagen

Schönauer

et al. 2011

J. Ceram. Soc. Japan

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For high temperature application, a planar SO 2 sensor using NASICON as an electrolyte and V 2 O 5 /WO 3 /TiO 2 + Au or Pt as a sensing electrode was fabricated and investigated. In the case of Pt electrodes, the sensor showed the strange response in temperature range from 300600°C. In the case of Au electrodes, the sensor showed a strange behavior at 300 and 400°C, while at 600°C the sensor showed good response to SO 2 . The highest sensitivity with 8083 mV/decade in the SO 2 range from 20 to 200 ppm was observed at 600°C, although offset shifting was observed in repeated measurements. The sensors showed the potential for good selectivity at 600°C in the case of Au electrodes. The fact that the electric potential difference of the sensor is strongly affected by the electrode materials may intend that the mechanism of the sensor is a mixed potential type.

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Application of V2O5/WO3/TiO2 for Resistive-Type SO2 Sensors

Cited by 55 publications

References 24 publications

Hierarchical methods to improve the performance of the SiC-FET as SO2 sensors in flue gas desulphurization systems

Hierarchical methods to improve the performance of the SiC-FET as SO2 sensors in flue gas desulphurization systems

SiC–FET based SO2 sensor for power plant emission applications

Planar potentiometric SO2 gas sensor for high temperatures using NASICON electrolyte combined with V2O5/WO3/TiO2 + Au or Pt electrode

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