Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
Search Results
Item The catalytic effect of chromium-doped ceria-praseodymium on soot oxidation activity and its kinetics(Springer, 2024) Patil, S.S.; Prasad Dasari, H.P.Soot generated from the partial combustion of diesel significantly contributes to air pollution, and catalytic oxidation is currently an effective method for removing diesel soot particles. The chromium-doped ceria-praseodymium (Cr-CP) catalyst system is synthesized via solution combustion synthesis and evaluated for soot oxidation activity, with a subsequent kinetics study conducted. The XRD analysis of the catalysts indicated a decrease in crystallite size and increased lattice strain and reactive facet ratios for all Cr-doped CP samples. Raman analysis verified the existence of oxygen vacancy peaks in all chromium-doped CP catalysts. X-ray photoelectron spectroscopy (XPS) revealed the presence of adsorbed H2O or molecular water peaks in the O1s spectra for the 5 Cr-CP catalyst, which also exhibited a high concentration of surface Cr3+ ions. Thermogravimetric analysis (TGA) of soot oxidation indicated that 5 Cr-CP exhibited a superior T50 of 393 ± 2 °C, mostly attributed to the presence of reducible surface Cr3+ ion species. Kinetic analysis was performed on all Cr-doped CP catalysts to assess the kinetic triplets: activation energy, pre-exponential factor, and reaction model. The activation energy was low (87 kJ mol−1, Ozawa method) for 15 Cr-CP, while the pre-exponential factor was higher for 5 Cr-CP (7.39 × 1010 min−1). The Cr-CP catalyst system adhered to a power law, indicating a phase boundary-controlled reaction characterized by nucleation and growth mechanisms. The consistency between experimental and calculated curves confirmed that the developed catalysts adhered to the Avrami-Erofeev equation (Am) or the nucleation and growth model. Graphical Abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.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 Soot Oxidation Kinetics on Nickel Oxide: Effects of Various Synthesis Techniques(Pleiades Publishing, 2024) Patil, S.S.; Prasad Dasari, H.P.; Gouramma, P.; Harshini, H.Abstract: Nickel oxide (NiO) nanoparticles were synthesized using four different methods: microwave co-precipitation (MCP), solution combustion synthesis (SCS), direct nitrate calcination (DNC), and the sol-gel process (SGP), incorporating organic additives such as glucose and fructose. X-ray diffraction and Raman spectroscopy analyses revealed that the NiO nanoparticles formed a face-centered cubic phase characterized by Ni–O bond stretching. The SCS method produced NiO nanoparticles with higher lattice strain, smaller crystallite size, and an increased facet ratio ({110}) compared to the other methods. Transmission electron microscopy indicated that the order of nano-agglomeration size for the NiO nanoparticles was DNC > MCP > SGP > SCS. The NiO nanoparticles synthesized via SCS, SGP and MCP exhibited irregular hexagonal shapes. Among the synthesized nanoparticles, those produced by the SCS method demonstrated the highest catalytic activity (T50 = 478°C), followed by DNC (T50 = 492°C), MCP (T50 = 495°C), and SGP (T50 = 538°C). A kinetic study was conducted to evaluate key parameters, including activation energy, preexponential factor, and reaction model. The experimental curves of soot conversion were compared with theoretical curves derived from the evaluated kinetic parameters. The NiO nanoparticles synthesized via SCS exhibited the highest kinetic activity with the enhanced reaction rate at lower temperatures. © Pleiades Publishing, Ltd. 2024.