Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
9 results
Search Results
Item Ceria-samarium binary metal oxides: A comparative approach towards structural properties and soot oxidation activity(Elsevier B.V., 2018) Anjana, A.P.; Geethu, J.; P, M.R.; Prasad Dasari, H.P.; Lee, J.-H.; Harshini, H.; Bhaskar Babu, G.U.Binary metal oxides of CeO2-Sm2O3 (CSx, x varies from 10 to 90 mol%) along with pure CeO2 and Sm2O3 were synthesised successfully by the EDTA-Citrate method. From XRD, Raman spectroscopy and UV–vis DRS results, the whole composition of metal oxides exist in three phases: (fluorite phase (F) (CS10-CS30), bi-phase (fluorite (F) + cubic (C)) (CS30-CS90) and cubic phase (C) (Sm2O3)). For CSx samples, the calculated band gap energy values obtained from the UV–vis DRS results were in between 3.0–5.1 eV and fluorite phase samples (CS10–CS30) displayed lower band gap energy values (3.04–3.07 eV) than compared to the samples in other phases. Similarly, from XPS analysis, fluorite phase samples (CS10–CS30) showed higher surface oxygen vacancy concentration than compared to samples in other phases. Catalytic activity for soot oxidation is carried out on CSx samples, and the T50 temperature is in between 480–540 °C. Fluorite phase samples (CS10 CS30) showed higher surface area, lower degree of agglomeration, lower band gap energy, higher oxygen vacancy concentration and better catalytic activity for soot oxidation. Among all the CSx samples, CS10 sample displayed highest surface area (38 m2/g), lowest degree of agglomeration (0.36), lowest band gap energy (3.04 eV), highest oxygen vacancy concentration (64%) and highest soot oxidation activity (T50 = 480 °C). The order of the soot oxidation activity of CSx samples followed the same trend of band gap energy values. © 2018 Elsevier B.V.Item Surface morphology and phase stability effect of Ceria-Hafnia (CHx) binary metal oxides on soot oxidation activity(Elsevier B.V., 2018) Anjana, A.P.; Prasad Dasari, H.P.; Harshini, H.; Babu, G.U.B.CeO2-HfO2 (CHx) binary metal oxides over whole composition range (0–100%) are synthesised using the EDTA-Citrate method and calcined at 600 °C/5 h. From XRD analysis, the sample series are classified as fluorite (F) phase for CH10-CH30, hybrid (F + M) phase for CH40-CH90 and monoclinic (M) phase for CH100 sample, respectively and the results were further confirmed using Raman spectroscopy. From SEM analysis, a clear surface morphology change is noticed for fluorite, hybrid and monoclinic phases of the CHx binary metal oxides. Further, Selected Area Electron Diffraction (SAED) analysis also confirmed the single and hybrid phases of CHx binary metal oxides. The soot oxidation for the CHx binary metal oxides displayed high catalytic activity for Fluorite phase (CH10 ? CH30) samples and a decrease in catalytic activity is noticed for the Hybrid phase (CH40 ? CH90) samples. The change in catalytic activity coincides with the change in the surface morphology and phase change for the CHx binary metal oxides. Among the Fluorite phase samples, CH10 sample displayed the highest catalytic activity (T50 = 430 °C) with higher surface area (29 m2/g), lower particle size (26 nm), lower degree of agglomeration (? = 2.8) higher surface oxygen concentration (44%). Isothermal-Time-on-stream (ITOS) analysis also showed that the CH10 sample can achieve T50 in a shorter time than compared to other CHx binary metal oxides. Surface morphology and phase stability can also play as key descriptors in screening CHx binary metal oxides for soot oxidation activity. © 2018 Elsevier B.V.Item Effect of morphology and oxidation state of nickel on diesel soot oxidation activity(Elsevier Ltd, 2022) Vijay, M.P.A.; Patil, S.S.; Madhura, D.R.; Anjana, A.P.; Gouramma, P.; Prasad Dasari, H.P.; Arya, S.B.; Harshini, H.NiO sample is synthesized using the EDTA citrate complex method and calcined at 600 °C/5 h. Ni sample was acquired by reducing NiO to Ni at 600 °C in 4% H2/N2 atmosphere. Its physicochemical properties were obtained by XRD and Raman spectroscopy analysis, where it confirmed the complete reduction of NiO to Ni. SEM and TEM micrographs revealed a drastic particle growth for the Ni, indicating NiO sintering during the reduction process and a considerable surface morphology change. Ozawa and KAS methods were used to calculate the mean activation energy (Ea) value. NiO displayed lower Ea than Ni. Hence, NiO showed better catalytic activity than Ni. © 2022Item Printex-U soot oxidation kinetic behaviour over Alumina and Quartz(Elsevier Ltd, 2022) Ganiger, S.; Patil, S.S.; Prasad Dasari, H.P.; Priyanka, R.; Kollimarla, S.Printex-U carbon (Pure Soot, S0) on alumina (SA) and quartz (SQ) powder were considered to understand the behaviour of oxidation reaction and kinetic analysis. A similar model of the single-step reaction was followed by the Soot (S0) and SA sample, while SQ followed a complex mechanism of multiple-step reactions. From the experimental and theoretical calculations, it was observed that there was a slight decrease in the T50 temperature for SA, which also had the lowest Ea, but there was an increase in T50 and Ea for SQ compared to the S0 sample. From the present study, it can be understood that the alumina enhanced the catalytic activity when compared to pure soot alone, whereas quartz inhibited the activity. The T50 temperature, Ea, and A calculated were obtained in SA < S0 < SQ. The soot properties and their kinetics will further help to design catalyzed diesel particulate filters. © 2021 Elsevier LtdItem A Negative Effect of Niobium-Doped Ceria on Soot Oxidation Activity‡(John Wiley and Sons Inc, 2022) Patil, S.S.; Naik, S.; Ramesh, M.D.; Harshini, H.; Prasad Dasari, H.P.Niobium-doped ceria catalysts were synthesized to study soot oxidation activity. X-Ray diffraction (XRD) and Raman analysis of the samples revealed the presence of a fluorite structure of CeO2 for all the doped samples. The T50 temperature of the pure CeO2 sample was more significant than that of bare soot. The high catalytic activity of the CeO2 catalyst can be attributed to the low crystallite size, high facet ratio, and the large Brunauer-Emmett-Teller (BET) surface area as compared to Nb-doped samples. The activation energy calculated by both Ozawa and KAS methods were found to be low for CeO2 when compared to Nb-doped samples. CeO2 resulted in better soot oxidation activity with low activation energy. © 2022 Wiley-VCH GmbHItem An investigation on copper-loaded ceria-praseodymium catalysts for soot oxidation activity and its kinetics(Springer Science and Business Media Deutschland GmbH, 2024) Patil, S.S.; Prasad Dasari, H.P.The Cu-loaded Ce-Pr catalyst series was successfully developed to study their performance on soot oxidation activity and its kinetic behavior. The doped samples showed a similar trend for cubic fluorite structure except for CuO, which possessed a monoclinic structure from the XRD analysis. Facet ratios [{100}/{111} and {110}/{111}] for the reactive planes were calculated from XRD spectra; the ratio was high for the 5 Cu-CP catalysts. The oxygen vacancy peaks were noticed from Raman spectra for the doped samples. 5 Cu-CP displayed the better catalytic activity of T50 = 402 °C, which may be attributed to high reactive planes and better reducibility. The addition of Cu showed a slight enhancement in catalytic activity compared to CP and pure Ce. The kinetic triplets were evaluated: the activation energy (Ea), pre-exponential factor (A), and the reaction model. Pure Ce displayed the lowest Ea and A values, whereas pure Cu showed high Ea and A values by all the methods. Graphical abstract: (Figure presented.) © The Author(s) under exclusive licence to Associação Brasileira de Engenharia Química 2023.Item Ceria-Terbium-based electrospun nanofiber catalysts for soot oxidation activity and its kinetics(Taiwan Institute of Chemical Engineers, 2024) Patil, S.S.; Kumar, R.; Prasad Dasari, H.P.Background: Ceria-based materials have an excellent potential to be catalysts for catalytic three-way converters in the automobile industry. Developing Ceria-based nanofiber catalysts can be a significant approach for further exploring the application of these materials in automobile industries. Methods: In this study, Ag, Cu, or Co doped Ceria–Terbium nanofibers were synthesized using the electrospinning technique. The obtained nanofiber catalysts were characterized using FE-SEM, XRD, FT-Raman Spectroscopy, and BET-BJH analysis and tested for soot oxidation activity and its kinetics. Significant findings: FE-SEM examination reveals that the obtained nanofibers have a diameter ranging from around 100 to 600 nm. CeTbCo nanofibers exhibited a reduced particle size and enhanced pore formation. The XRD investigation revealed that all the nanofibers displayed a face-centered fluorite structure of CeO2. In Raman spectroscopy analysis, CeTbCo nanofibes showed the emergence of a secondary Co3O4 phase. The CeTbCo nanofiber catalyst showed better SBET (specific surface area) (66 m2/g) and average pore size (12.08 nm) and total pore volume (0.223 cc/g)), better soot oxidation activity (T50 = 347 ℃) than other nanofiber catalysts. The CeTbCo nanofiber catalyst exhibited an activation energy of 132 kJ mol−1 and a pre-exponential factor (ln (A)) of 25.63 min−1. © 2024 Taiwan Institute of Chemical EngineersItem Soot oxidation activity and kinetics of Ce0.9M0.1O2-δ (M = Cs, Mg, Ca) catalysts: Impact of Cs doping in ceria and impact of nanorods on catalytic activity(Institution of Chemical Engineers, 2024) Nayak, A.S.; Patil, S.S.; Prasad Dasari, H.P.; Telaginatot, D.; Rynjah, M.; Cheruku, S.Solution combustion method is used to synthesize Ce0.9M0.1O2-δ (M = Cs, Mg, Ca) catalysts and calcined at 600 °C/5 h. XRD and Raman Spectroscopy Analyses the chemical structure, the phases observed, and the oxygen defects in the synthesized catalysts. A cubic fluorite structure of CeO2 has been noticed for all the catalysts from XRD and Raman Spectroscopy analyses. FE-SEM micrographs are used to analyze the morphology of the Ce0.9M0.1O2-δ (M = Cs, Mg, Ca) catalysts. Ce0.9Cs0.1O2-δ catalyst shows the presence of nanorods (diameter: 63 nm), which are not seen in the other catalysts. The redox and surface properties of the synthesized catalysts are tested by H2-Temperature Programmed Reduction (H2-TPR) and O2-Temperature Programmed Desorption (O2-TPD), respectively. The Ce0.9Cs0.1O2-δ catalyst shows the greatest degree of reducibility from TPR studies and for the Ce0.9Cs0.1O2-δ catalyst, the oxygen species evolved from the O2-TPD studies are also the highest. Thermogravimetric Analysis (TGA) has been used to carry the soot oxidation activity of the developed catalysts. Soot oxidation kinetic studies have been conducted at different heating rates (5, 10, and 15 °C/min) for the catalysts. The kinetic triplets for the developed catalysts have been obtained, and rate plots ([Formula presented] vs. temperature) and Arrhenius plots (ln(k) vs. [Formula presented]) have been developed for the catalysts. From the soot oxidation and kinetic studies for the developed catalysts, Ce0.9Cs0.1O2-δ shows better soot oxidation activity (T50 = 372 °C) than the other two catalysts, while Ce0.9Mg0.1O2-δ (T50 = 556 °C) shows the lowest soot oxidation activity. All the catalysts follow a non-integral exponential model for soot oxidation, and the Ce0.9Cs0.1O2-δ catalyst has the lowest activation energy. © 2024 Institution of Chemical EngineersItem Study of CO oxidation activity of NiO-PDC and NiO-YSZ catalysts coated on alumina wash-coated honeycomb cordierite monolith(Springer Science and Business Media Deutschland GmbH, 2025) Wagay, A.A.; Shourya, A.; Patil, S.S.; Shirasangi, R.; Prasad Dasari, H.P.In this study, the EDTA-Citrate method was employed to synthesize NiO-PDC (NPC) and NiO-YSZ (NYZ) powder catalysts in nanostructured form. Subsequently, the catalysts were slurry dip-coated onto monolith cordierite substrates with alumina, using a one-step coating approach, and their CO oxidation activity was tested. The coating was achieved by first mixing the catalyst with the alumina suspension to prepare a homogeneous slurry, which was then used for dip coating onto the monolith. The adherence test was performed on the coated monolith to evaluate the mechanical stability of the catalyst-alumina composite layer. The coating was visually confirmed through optical imaging. The remaining powders (after coating) were then subjected to BET surface area, XRD, Raman spectroscopy, H2 TPR and O2 TPD analysis for characterization. Raman spectra showed that NPC exhibited higher oxygen vacancies than NYZ. H2 TPR and O2 TPD provided better evidence of the reduction potential and O2 desorption of NPC respectively. NPC/cord demonstrated the highest catalytic activity (T50 = 165 °C) compared to NYZ/cord (T50 = 215 °C) and bare cordierite (T50 = 777 °C), which is attributed to its better redox properties and higher oxygen vacancies. The effect of flow rate and heating rate on CO oxidation was studied on NPC/cord and NYZ/cord. The long-term stability of the NPC/cord and NYZ/cord were tested through 5-h and 50-h isothermal studies. © The Author(s) under exclusive licence to Associação Brasileira de Engenharia Química 2025.