Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
6 results
Search Results
Item Studies on the Solid Oxide Cell Perovskite Electrode Materials for Soot Oxidation Activity(Springer, 2019) Shenoy, C.S.; Patil, S.S.; Govardhan, P.; Shourya, A.; Prasad Dasari, H.P.; Saidutta, M.B.; Harshini, H.Solid oxide cell (SOC) perovskite electrode materials (BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3-?), LSCF (La0.6Sr0.4Co0.2Fe0.8O3-?) and LSCM (La0.75Sr0.25Cr0.5Mn0.5O3-?)) were synthesised using microwave-assisted reverse-strike co-precipitation method and tested for soot oxidation activity. The calcined perovskite materials were characterized using FT-IR, XRD, SEM and BSE, BET and BJH and XPS analysis. The mean activation energy for soot oxidation was calculated from Ozawa plots at various heating rates (5, 10, 15 and 20 K/min) at different levels of soot conversions (T10 to T90) for BSCF, LSCM and LSCF perovskite materials and was around 133 ± 11.5, 138 ± 9.9 and 152 ± 7.2 kJ/mol, respectively. Irrespective of the heating rates, BSCF material showed the lowest T50 temperature than compared to other samples, and it is correlated to the presence of Fe3O4 as a secondary phase. © 2019, Springer Nature Switzerland AG.Item Effect of Ag loading on praseodymium doped ceria catalyst for soot oxidation activity(Springer, 2022) Govardhan, P.; Anjana, A.P.; Patil, S.S.; Prasad Dasari, H.P.; Harshini, H.; Shourya, A.Silver-loaded praseodymium doped ceria (XAg/PDC) was synthesized by microwave-assisted co-precipitation and wetness impregnation. XRD confirms the fluorite structure of ceria without secondary phase, and Raman spectroscopy represents the increased generation of oxygen vacancies with Ag loading. The TEM analysis shows lattice fringes corresponding to both CeO2 and Ag on the surface. The BET and BJH analysis of catalyst confirms the high porosity accompanied by high surface area and pore diameter of 5Ag/PDC and 15Ag/PDC, making it more active for the oxidation reaction. From the XPS analysis the amount of surface Ce3+ concentration and the surface chemisorbed oxygen species (O2 2) is high for 5Ag/PDC and 15Ag/PDC, in line with XRD and Raman results. The soot oxidation T50 temperature follows the trend: 5Ag/PDC∼15Ag/PDC<10Ag/PDC<20Ag/PDC<0Ag/PDC. The Ag loading increased the surface reducibility of cerium ions and thus 5 wt% was optimized. © 2021, The Korean Institute of Chemical Engineers.Item Manganese doped Ceria (Ce1−xMnxO2−δ (x = 0–0.3)) catalysts synthesized by EDTA–Citrate method for soot oxidation activity(Springer Science and Business Media Deutschland GmbH, 2022) Shourya, A.; Prasad Dasari, H.P.Ceria–Manganese oxide catalysts (Ce1−xMnxO2−δ where x = 0, 0.05, 0.1, 0.2, and 0.3, termed CM0, CM5, CM10, CM20, and CM30, respectively) were synthesized by EDTA–Citrate method, calcined at 600 °C/5 h, and checked for soot oxidation activity. The XRD spectra exhibited the cubic fluorite phase formation and complete solubility of Mn in Ceria lattice up to CM30. BET and BJH analysis showed that the surface area and pore volume had an appreciable influence on the soot oxidation activity, as seen in the case of CM5, which had superior BET surface area (50 m2/g) as well as pore volume (0.128 cc/g). The Raman spectra revealed secondary phase formation of Mn3O4 peak in CM20 and CM30. FESEM analysis was carried out for all the CMX samples. TEM images displayed the decrease in the particle size of CM5 with the inclusion of Manganese ions into the Ceria lattice. SAED analysis provided evidence for the polycrystalline nature of CM5 compared to CM0. Soot oxidation activity was carried out in tight contact conditions and an air atmosphere. CM5 with a T50 of 360 °C had the least among the CMX catalysts. Ozawa and KAS methods were used to determine the soot oxidation activation energy. CM5 had the least activation energy with 118 kJ/mol (Ozawa) and 114 kJ/mol (KAS). High specific surface area, pore-volume, relatively higher exposed (220) and (200) planes, the lower activation energy for soot oxidation activity, high synergy, and robust interactions between Ceria and Manganese oxides were pivotal in the decrease in soot combustion temperature of the CM5 catalyst. Graphical abstract: [Figure not available: see fulltext.] © 2022, Institute of Chemistry, Slovak Academy of Sciences.Item Formation of nano-rod structures in manganese-rich ceria–manganese mixed oxides and their soot oxidation activity(Elsevier B.V., 2023) Shourya, A.; Prasad Dasari, H.P.EDTA-citrate synthesized manganese-rich ceria–manganese oxide catalysts (Ce1−xMnxO2−δ; where x = 1 to 0.6, termed CM100, CM90, CM80, CM70, CM60, CM50 and CM40 respectively) were obtained after calcination at 600 °C/5 h, characterized and tested for soot oxidation activity. Mn3O4 and Mn2O3 phases were observed in the XRD spectra; with the increase in the ceria concentration, cubic fluorite phase formation was observed from CM80 to CM40. BET and BJH analyses revealed that the pore diameter and volume had a meaningful impact on the soot oxidation activity, as seen for CM80 which had a BET surface area of 31 m2/g, pore diameter of 21.119 nm, and a pore volume of 0.1637 cc/g. The formation of the Mn3O4 peak in all the synthesized catalysts and ceria's cubic fluorite F2g peak (452 cm −1) were observed from CM80 to CM40 from Raman spectral analysis. FESEM analysis of all the CMX samples revealed an intriguing aspect, the appearance of nano-rods. These nano-rods were observed in the HRTEM imaging as well. The high-resolution imaging and SAED analysis proved that the nano-rod structures were primarily due to the α-MnO 2 phase. The mixture of agglomerates and nano-rods profoundly affected the soot oxidation activity of the synthesized samples. CM70 had a minimum T50 of 389 °C among the CMX catalysts. The activation energy was reckoned with the Ozawa and KAS methods. CM50, with 131 kJ/mol for Ozawa and 127 kJ/mol for the KAS method, had the lowest values among the chosen catalysts. Synergistic interactions between ceria and the manganese oxides, considerable specific surface area, pore diameter, pore volume, substantially higher exposed (220) and (200) planes and the formation of the nano-rods helped to lower the activation energy for soot oxidation activity and consequently a reduction in the soot oxidation temperature of CM50 to CM70. The concentration of the nano-rods rendered a considerable role in reducing the T50 temperatures of the CMX catalysts. © 2023 Elsevier B.V.Item Dip coating of ceria–manganese mixed oxides on cordierite and its CO oxidation activity(Springer Science and Business Media Deutschland GmbH, 2024) Shourya, A.; Prasad Dasari, H.P.; Wagay, A.A.Dip coating method was utilized for wash-coating alumina onto cordierite honeycomb substrate, followed by catalyst coating by sol–gel dip coating of CMX(X = 0, 5, 70, and 100 corresponding to Ce1-xMnxO2-δ, where x = 0, 0.5, 0.7, and 1) to obtain CM0/Al2O3/Cord, CM5/Al2O3/Cord, CM70/Al2O3/Cord, and CM100/Al2O3/Cord. The sol–gel was obtained from the EDTA–citrate method. XRD, BET, and BJH analysis was conducted on samples Cord to CM100/Al2O3/Cord. An intense peak of ceria at 462.53 cm−1 and that of Mn3O4 was observed at 658 cm−1 in the Raman spectra analysis. The adherence test was conducted to test the mechanical stability of the wash-coat and catalyst layer. The visual evidence of coating was furnished by optical imaging and FESEM analysis. Ultrafine particles with high porosity were observed in sample Al2O3/Cord. Cracks were observed in the FESEM images of CM0/Al2O3/Cord to CM100/Al2O3/Cord samples. CO oxidation studies were performed on the samples Cord to CM100/Al2O3/Cord. CM70/Al2O3/Cord performed the best among all other samples with a T50 temperature of 157 °C. The activation energy of CO oxidation was calculated using the Ozawa method for samples CM0/Al2O3/Cord to CM100/Al2O3/Cord. 50 h long-term CO oxidation stability experiments were also conducted on samples CM0/Al2O3/Cord to CM100/Al2O3/Cord. The synergistic effects of ceria and manganese, combined with fine dispersion of the catalyst, pore characteristics, and cracks improving diffusivity, pitched CM70/Al2O3/Cord to have the best CO oxidation activity. © The Author(s), under exclusive licence to the Institute of Chemistry, Slovak Academy of Sciences 2024.Item 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.