liu.seSearch for publications in DiVA
Change search
Link to record
Permanent link

Direct link
BETA
Darmastuti, Zhafira
Publications (10 of 16) Show all publications
Darmastuti, Z., Bur, C., Lindqvist, N., Anderson, M., Schutza, A. & Lloyd Spetz, A. (2015). Hierarchical methods to improve the performance of the SiC - FET as SO2 sensors in flue gas desulphurization system. Sensors and actuators. B, Chemical, 206, 609-616
Open this publication in new window or tab >>Hierarchical methods to improve the performance of the SiC - FET as SO2 sensors in flue gas desulphurization system
Show others...
2015 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 206, p. 609-616Article in journal (Refereed) Published
Abstract [en]

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 SO2 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 SO2 concentration range (up to 5000 ppm). The results from the SO2 quantification showed a significantly improved fit to corresponding reference instrument (FTIR) values.

Place, publisher, year, edition, pages
Elsevier, 2015
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:liu:diva-106212 (URN)10.1016/j.snb.2014.09.113 (DOI)000345234200079 ()
Available from: 2014-04-29 Created: 2014-04-29 Last updated: 2017-12-05
Darmastuti, Z., Ojamäe, L., Andersson, M. & Lloyd Spetz, A. (2014). SiC-FET as SO2 Sensors - Detection Mechanism Studies. In: Proc IMCS 2014, Buenos Aires, Argentine, March 17-19, MPS-T3-4: . Paper presented at IMCS 2014, Buenos Aires, Argentine, March 17-19.
Open this publication in new window or tab >>SiC-FET as SO2 Sensors - Detection Mechanism Studies
2014 (English)In: Proc IMCS 2014, Buenos Aires, Argentine, March 17-19, MPS-T3-4, 2014Conference paper, Poster (with or without abstract) (Refereed)
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-113321 (URN)
Conference
IMCS 2014, Buenos Aires, Argentine, March 17-19
Available from: 2015-01-15 Created: 2015-01-15 Last updated: 2018-09-14
Darmastuti, Z., Bur, C., Möller, P., Rahlin, R., Lindqvist, N., Andersson, M., . . . Lloyd Spetz, A. (2014). SiC-FET based SO2 sensor for power plant emission applications. Sensors and actuators. B, Chemical, 194, 511-520
Open this publication in new window or tab >>SiC-FET based SO2 sensor for power plant emission applications
Show others...
2014 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 194, p. 511-520Article in journal (Refereed) Published
Abstract [en]

Thermal power plants produce SO2 during combustion of fuel containing sulfur. One way to decrease the SO2 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 SO2, that it is difficult to desorb from the catalyst surface, makes it known as catalyst poison. It is difficult to quantify the SO2 with static operation, even at the optimum operation temperature of the sensor due to low response levels and saturation already at low concentration of SO2. The challenge of SO2 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 SO2. 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 SO2 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 SO2 concentration from the reference instrument of the pilot plant.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
SO2 sensors; SiC-FET; Pt; Temperature cycled operation (TCO); Desulphurization; Power plant
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-105569 (URN)10.1016/j.snb.2013.11.089 (DOI)000331575400067 ()
Available from: 2014-03-31 Created: 2014-03-27 Last updated: 2017-12-05Bibliographically approved
Darmastuti, Z. (2014). SiC-FET Gas Sensors Developed for Control of the Flue Gas Desulfurization System in Power Plants Experimental and Modeling: Experimental and Modeling. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>SiC-FET Gas Sensors Developed for Control of the Flue Gas Desulfurization System in Power Plants Experimental and Modeling: Experimental and Modeling
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electricity and power generation is an essential part of our life. However, powergeneration activities also create by-products (such as sulphur oxides, nitrogen oxides,carbon monoxide, etc), which can be dangerous when released to the atmosphere.Sensors, as part of the control system, play very vital role for the fluegas cleaning processes in power plants. This thesis concerns the development ofSilicon Carbide Field Effect Transistor (SiC-FET) gas sensors as sensors for sulfurcontaining gases (SO2 and H2S) used as part of the environmental control systemin power plants. The works includes sensor deposition and assembly, sensinglayer characterization, operation mode development, performance testing of thesensors in a gas mixing rig in the laboratory and field test in a desulfurization pilotunit, and both experimental and theoretical studies on the detection mechanismof the sensors.

The sensor response to SO2 was very small and saturated quickly. SO2 is a verystable gas and therefore reaction with other species requires a large energy input.SO2 mostly reacts with the catalyst through physisorption, which results in lowresponse level. Another problem was that once it finally reacted with oxygen andadsorbed on the surface of the catalyst in form of a sulfate compound, it is desorbedwith difficulty. Therefore, the sensor signal saturated after a certain timeof exposure to SO2. Different gate materials were tested in static operation (Pt,Ir, Au), but the saturation phenomena occurred in all three cases. Dynamic sensoroperation using temperature cycling and multivariate data analysis could mitigatethis problem. Pt-gate sensors were operated at several different temperatures in acyclic fashion. One of the applied temperatures was chosen to be very high for ashort time to serve as cleaning step. This method was also termed the virtual multisensor method because the data generated could represent the data from multiplesensors in static operation at different temperatures. Then, several features of thesignal, such as mean value and slope, were extracted and processed with multivariatedata analysis. Linear Discrimination Analysis (LDA) was chosen since itiiiallows controlled data analysis. It was shown that it was possible to quantify SO2with a 2-step LDA. The background was identified in the first step and SO2 wasquantified in the second step. Pt sensors in dynamic operation and 2-step LDAevaluation has also demonstrated promising results for SO2 measurement in thelaboratory as well as in a desulfurization pilot unit. For a commercial sensor, algorithmhave to be developed to enable on-line measurement in real time.

It was observed that Ir-gate sensors at 350oC were very sensitive to H2S. The responseobtained by Ir sensors to H2S was almost five times larger than that of Ptsensors, which might be due to the higher oxygen coverage of Ir. Moreover, Irsensors were also more stable with less drift during the operation as a result ofhigher thermal stability. However, the recovery time for Ir sensors was very long,due to the high desorption energy. Overall, the Ir sensors performed well whentested for a leak detection application (presence of oxygen and dry environment).The geothermal application, where heat is extracted from the earth, requires thesensor to be operated in humid condition in the absence (or very low concentration)of oxygen, and this poses a problem. Temperature cycle operation and smartdata evaluation might also be an option for future development.

Along with the sensor performance testing, a study on the detection mechanismwas also performed for SO2 sensor, both experimentally and theoretically. The experimentincluded the study of the species formed on the surface of the catalystwith DRIFT (diffuse reflectance infrared frourier transform) spectroscopy and theanalysis of the residual gas with mass spectroscopy. Explanatory investigation ofthe surface reactions was performed using quantum-chemical calculations. Theoreticalcalculations of the infrared (IR) vibration spectra was employed to supportthe identification of peaks in the DRIFT measurement. Based on the study on theresidual gas analysis and quantum-chemical calculations, a reaction mechanismfor the SO2 molecule adsorption on the sensor surface was suggested.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. p. 44
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1587
Keywords
SiC-FET sensors, temperature cycle operation, detection mechanism studies, SO2, H2S
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-106224 (URN)10.3384/diss.diva-106224 (DOI)978-91-7519-366-3 (ISBN)
Public defence
2014-06-03, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Funder
Vinnova
Available from: 2014-05-13 Created: 2014-04-29 Last updated: 2015-03-09Bibliographically approved
Bounechada, D., Darmastuti, Z., Andersson, M., Ojamäe, L., Lloyd Spetz, A., Skoglundh, M. & Carlsson, P.-A. (2014). Vibrational Study of SOx Adsorption on Pt/SiO2. The Journal of Physical Chemistry C, 118(51), 29713-29723
Open this publication in new window or tab >>Vibrational Study of SOx Adsorption on Pt/SiO2
Show others...
2014 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 51, p. 29713-29723Article in journal (Refereed) Published
Abstract [en]

The formation of ad-SOx species on Pt/SiO2 upon exposure to SO2 in concentrations ranging from 10 to 50 ppm at between 200 and 400 degrees C has been studied by in situ diffuse reflectance infrared Fourier transformed spectroscopy. In parallel, first-principles calculations have been carried out to consolidate the experimental interpretations. It was found that sulfate species form on the silica surface with a concomitant removal/rearrangement of silanol groups. Formation of ad-SOx species occurs only after SO2 oxidation to SO3 on the platinum surface. Thus, SO2 oxidation to SO3 is the first step in the SOx adsorption process, followed by spillover of SO3 to the oxide, and finally, the formation of sulfate species on the hydroxyl positions on the oxide. The sulfate formation is influenced by both temperature and SO2 concentration. Furthermore, exposure to hydrogen is shown to be sufficiently efficient as to remove ad-SOx species from the silica surface.

Place, publisher, year, edition, pages
American Chemical Society, 2014
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-114017 (URN)10.1021/jp506644w (DOI)000347360200028 ()
Note

Funding Agencies|Chalmers University of Technology; Swedish Energy Agency; AB Volvo; ECAPS AB; Haldor Topsoe A/S; Scania CV AB; Volvo Car Corp. AB; Wartsila Finland Oy; Swedish Research Council (VR)

Available from: 2015-02-06 Created: 2015-02-05 Last updated: 2017-12-04
Lloyd Spetz, A., Darmastuti, Z., Bur, C., Huotari, J., Bjorklund, R., Lindqvist, N., . . . Andersson, M. (2013). Chemical sensor systems for environmental and emission control. In: Proc. SPIE Defence, Security + Sensors: . Paper presented at Micro- and Nanotechnology Sensors, Systems, and Applications V Conference; Baltimore, MD; United States.
Open this publication in new window or tab >>Chemical sensor systems for environmental and emission control
Show others...
2013 (English)In: Proc. SPIE Defence, Security + Sensors, 2013Conference paper, Published paper (Refereed)
Abstract [en]

Focusing on environment and health aspects, the importance of monitoring and controlling dangerous gases and particulate matter increases. For this purpose we present a new version of silicon carbide based gas sensors with improved properties and suitable for high temperature and harsh environments such as power plants or car exhausts. Development of sulfur dioxide sensors for a power plant application is described as well as sensors for detection of ammonia in connection with the SCR process where urea is converted to ammonia, which reduces nitric oxide components in the exhausts. We also describe progress on nanoparticle detection, especially related to detection of the content of adsorbed particles through heating and detection of emitted molecules by a sensor array. Some results are also presented from impedance spectroscopy for detection of the concentration of nanoparticles but with the potential to reveal more details about the particles such as shape and kind of particles. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:liu:diva-92406 (URN)10.1117/12.2016795 (DOI)000325263900015 ()
Conference
Micro- and Nanotechnology Sensors, Systems, and Applications V Conference; Baltimore, MD; United States
Note

Invited talk, Lloyd Spetz

Available from: 2013-05-11 Created: 2013-05-10 Last updated: 2017-11-07
Lloyd Spetz, A., Darmastuti, Z., Bjorklund, R., Andersson, M., Bur, C., Schütze, A., . . . Lindqvist, N. (2013). Improved chemical sensors track and control emissions. SPIE - International Society for Optical Engineering
Open this publication in new window or tab >>Improved chemical sensors track and control emissions
Show others...
2013 (English)Other (Other (popular science, discussion, etc.))
Abstract [en]

Sensitive, low-cost silicon carbide-based gas sensors can detect toxic emissions and hazardous nanoparticulate matter in previously untenable environments.

Place, publisher, year, pages
SPIE - International Society for Optical Engineering, 2013
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:liu:diva-92459 (URN)10.1117/2.1201304.004839 (DOI)
Note

SPIE Newsroom

Available from: 2013-05-11 Created: 2013-05-11 Last updated: 2014-01-09
Darmastuti, Z., Bhattacharyya, P., Andersson, M., Kanungo, J., Basu, S., Käll, P.-O., . . . Lloyd Spetz, A. (2013). SiC-FET methanol sensors for process control and leakage detection. Sensors and actuators. B, Chemical, 187(SI), 553-562
Open this publication in new window or tab >>SiC-FET methanol sensors for process control and leakage detection
Show others...
2013 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 187, no SI, p. 553-562Article in journal (Refereed) Published
Abstract [en]

Two types of SiC based field effect transistor sensors, with Pt or Ir gate, were tested to detect methanol in the concentration range of 0–1600 ppm for both process control and leak detection applications. The methanol response was investigated both with and without oxygen, since the process control might be considered as oxygen free application, while the sensor is operated in air during leak detection. Pt sensors offered very fast response with appreciably high response magnitude at 200 °C, while Ir sensors showed both higher response and response time up to 300 °C, but this decreased considerably at 350 °C. Cross sensitivity effect in presence of oxygen, hydrogen, propene and water vapor was also investigated. The presence of oxygen improved the response of both sensors, which is favorable for the leak detection application. Hydrogen had a large influence on the methanol response of both sensors, propene had a negligible influence, while water vapor changed direction of the methanol response for the Pt sensor. The detection mechanism and different sensing behavior of Pt and Ir gate sensors were discussed in the light of model reaction mechanisms derived from hybrid density-functional theory quantum-chemical calculations.

Keywords
SiC-FET sensor, methanol, quantum-chemical calculation, Pt, Ir, gas sensor
National Category
Engineering and Technology Natural Sciences
Identifiers
urn:nbn:se:liu:diva-85636 (URN)10.1016/j.snb.2013.04.019 (DOI)000324298300081 ()
Available from: 2012-11-26 Created: 2012-11-26 Last updated: 2018-09-14Bibliographically approved
Darmastuti, Z., Bhattacharyya, P., Basu, S., Käll, P.-O., Ojamäe, L. & Lloyd Spetz, A. (2012). SiC - FET Sensors for methanol leakage detection. In: Proceeding of the 14th International Meeting on Chemical Sensors (IMCS 2012): . Paper presented at 14th International Meeting on Chemical Sensors (IMCS 2012), 20-23 May 2012, Nürnberg, Germany (pp. 1579-1582).
Open this publication in new window or tab >>SiC - FET Sensors for methanol leakage detection
Show others...
2012 (English)In: Proceeding of the 14th International Meeting on Chemical Sensors (IMCS 2012), 2012, p. 1579-1582Conference paper, Published paper (Other academic)
Abstract [en]

Pt and Ir SiC based Field Effect Transistor sensors were tested to detect low concentration of methanol (<200 ppm) for both process control and leak detection applications. Pt sensors gave good and very fast response at 200°C, while Ir sensors gave larger but much slower response. The presence of oxygen improved the response of the sensor which was favorable for the leak detection application. The influence of hydrogen and propene to the sensor response was also studied. Beside the experimental work, the detection mechanism and different sensing behavior of Pt and Ir were studied by quantum chemical calculations.

National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:liu:diva-92403 (URN)10.5162/IMCS2012/P2.5.3 (DOI)978-3-9813484-2-2 (ISBN)
Conference
14th International Meeting on Chemical Sensors (IMCS 2012), 20-23 May 2012, Nürnberg, Germany
Available from: 2013-05-10 Created: 2013-05-10 Last updated: 2015-03-09Bibliographically approved
Darmastuti, Z. (2012). SiCFET gassensors: theory, developent, and applications to flue gas cleaning processes  in power plants. (Licentiate dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>SiCFET gassensors: theory, developent, and applications to flue gas cleaning processes  in power plants
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Environmental and health concerns lead to stricter regulations on power plant emission. Sensors play an important role, not only as part of the process control to ensure that the effluent stays under the regulated values, but also to increase the pollution removal efficiency and to decrease the reagent consumption.

Previous studies, on the use of SiC based Field Effect Transistors (FET) as NH3 sensors in Tekniska Verken power plants and as CO sensors for the control of the domestic boilers, have shown promising results. Moreover, these sensors can withstand high temperature operation and are considerably cheaper than most conventional sensors used in power plants. The price of the sensors enable the installation of multiple sensors in one flue gas duct section, which lead to better monitoring of the flue gas uniformity. Based on that argument, this study is performed to determine whether it is possible to expand the possible application of SiC-FET sensors for the detection of other pollutants emitted by power plants. This thesis reports the characterization and performance testing of SiC-FET sensors towards other selected air pollutants: H2S, methanol as a product of CO2 hydrogenation, and SO2.

The study is performed by I-V characterization of the sensors toward the test gas in different background gases and studies of the detection mechanism. Detection mechanism studies include DRIFT spectroscopy, mass spectroscopy, and theoretical study of the surface reaction with Density Functional Theory (DFT).

Ir-gate SiC-FET sensors at 350oC show a very high sensitivity to H2S. The large response reduces the possibility of cross-sensitivity from other gases. Pt-gate sensors offer very fast response with decent response magnitude at 200oC for methanol. The presence of oxygen improves the response to methanol, which is favorable for the leak detection application. Besides oxygen, the influence of hydrogen, propene, and water vapor is also observed in the experiment with methanol. The detection mechanism and different  sensing behavior of Pt and Ir gates are illustrated with model reaction mechanisms on the surface of the metals. Sensor characterization has been performed for SO2 with several catalytic metal gates: Pt, Ir, Cu, and Au. The results suggest that a single sensor with any of Pt, Ir, Cu, and Au gates is able to detect the presence of SO2 in the air or nitrogen background. However, they are unable to measure different SO2 concentration. Moreover, the response level to SO2 is so small, that it will probably disappear if there is any other gas present in the mixture.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2012. p. 32
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1554
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-85637 (URN)LIU-TEK-LIC-2012:39 (Local ID)978-91-7519-764-7 (ISBN)LIU-TEK-LIC-2012:39 (Archive number)LIU-TEK-LIC-2012:39 (OAI)
Presentation
2012-11-30, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2012-11-26 Created: 2012-11-26 Last updated: 2015-03-09Bibliographically approved
Organisations

Search in DiVA

Show all publications