Faculty Publications
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Item MoVW-mixed oxide as a partial oxidation catalyst for methanol to formaldehyde(Elsevier Inc., 2006) Badekai Ramachandra, B.R.; Jung, S.C.; Kim, K.-S.; Choo, K.-Y.; Sung, J.-S.; Kim, T.-H.Mixed oxide with composition Mo0.65V0.25W 0.10Ox was synthesized and its catalytic activity for the selective oxidation of methanol to formaldehyde was investigated. The characterization by scanning electron microscopy, X-ray diffraction, energy dispersive X-ray and Fourier transform infra-red spectroscopy reveals that the prepared catalyst is inhomogeneous nanocrystalline Mo5O 14-type oxide with minor amount of MoO3-type and MoO 2-type material. Thermal activation treatment of the catalyst at 813K resulted in better crystalline sample. The overall structural analysis suggests that the catalytic performance of the MoVW-mixed oxide catalyst in partial oxidation of methanol is related to the formation of the Mo5O 14-type material. © 2006 Elsevier B.V. All rights reserved.Item Methanol selective oxidation to formaldehyde over a modified Fe-Mo catalyst with two different stoichiometric (Mo/Fe atomic ratio = 1.5 and 3.0) was studied experimentally in a fixed bed reactor over a wide range of reaction conditions. The physicochemical characterization of the prepared catalysts provides evidence that Fe2(MoO4)3 is in fact the active phase of the catalyst. The experimental results of conversion of methanol and selectivity towards formaldehyde for various residence times were studied. The results showed that as the residence time increases the yield of formaldehyde decreases. Selectivity of formaldehyde decreases with increase in residence time. This result is attributable to subsequent oxidation of formaldehyde to carbon monoxide due to longer residence time.(Selective oxidation of methanol to formaldehyde using modified iron-molybdate catalysts) Kim, T.-H.; Badekai Ramachandra, B.; Choi, J.-S.; Saidutta, M.B.; Choo, K.-Y.; Song, S.-D.; Rhee, Y.-W.2004Item Molybdenum based mixed oxide containing Mo0.65V 0.25W0.10 was investigated for the partial oxidation of methanol. The structural property and catalytic activity of the mixed oxide catalyst was studied by surface area (BET), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD). The thermal activation of the catalyst resulted increase in the conversion of methanol and the selectivity to formaldehyde. The thermal activation of the MoVW mixed oxide in nitrogen atmospheres induces partial crystallization of a Mo5O14-type oxide at 813 K. The SEM images of the thermally activated catalyst show needle like particles. These particles were agglomerates of platelet-like crystallites of a few hundreds of nanometers in size. SEM and EDX techniques show that the mixed oxide is characterized by an inhomogeneous elemental distribution on the length scale of a few microns. XRD of the thermally activated catalyst showed a nanocrystalline material identified as a mixture of Mo5O 14, MoO3 and MoO2-type MoVW oxides. The catalytic activity of the MoVW mixed oxide show a good conversion of methanol and selectivity to formaldehyde. © 2005 Springer Science+Business Media, Inc.(Partial oxidation of methanol to formaldehyde on molybdenum based mixed oxide catalyst) Badekai Ramachandra, B.; Choi, J.-S.; Choo, K.-Y.; Sung, J.-S.; Song, S.-D.; Kim, T.-H.2005Item Synthesis and characterization of nanocrystalline Mo-V-W-Fe-O mixed oxide catalyst and its performance in selective methanol oxidation(2007) Badekai Ramachandra, B.; Choi, J.-S.; Kim, T.-H.A mixed oxide catalyst containing Mo, V, W and Fe with the composition of 63, 23, 09 and 06 wt% respectively for the selective oxidation of the methanol to formaldehyde is in reported in this paper for the first time. The characterization of the catalyst was done using BET surface analysis, X-ray diffraction (XRD), Infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Energy dispersive X-ray (EDX). The mixed oxide after calcination at 673 K in N2 which was subjected for the thermal activation in N 2flow at 813 K was used for the methanol selective oxidation. The thermal treatment shows enhanced catalytic performance. Thermal activation of the nanocrystalline Mo0.63V23W0.09Fe 0.06O x precursor oxide in nitrogen atmospheres induces partial crystallization of a Mo5O14-type oxide only in a narrow temperature range up to 813 K. XRD showed that the thermally activated mixed oxide consists of a mixture of a majority of crystalline Mo 5O14-type oxide and of small amounts of crystalline MoO3-type and MoO2-type oxides. The structural analysis suggests that the improvement of the catalytic performance of the MoVWFe oxide catalyst in the selective oxidation of methanol is related to the formation of the catalytic active site such as Mo5O14-type mixed oxide. © 2007 Springer Science+Business Media, LLC.Item Mechanical and acoustic properties of areca fiber reinforced phenol formaldehyde composites(2010) Mohan Kumar, G.C.M.In this paper, mechanical and acoustic properties of natural areca fiber reinforced phenol formaldehyde composite are studied. Areca fiber composites were prepared using phenol formaldehyde with randomly distributed fibers. Strength of the composite is determined and other tests like adhesion tensile test, moisture absorption test, and biodegradable were also carried out. Acoustic tests are carried out to measure the sound transmission loss (STL) of the cured composite and compared with wood based particle board. The results show that the fully developed material has higher STL for frequencies up to 3 kHz compared to wood-based particle boards.Item Room-temperature detection of ammonia and formaldehyde gases by La xBa1?xSnO3?? (x = 0 and 0.05) screen printed sensors: effect of ceria and ruthenate sensitization(Springer Science and Business Media Deutschland GmbH, 2021) Manjunath, G.; Vardhan, R.V.; Praveen, L.L.; Pothukanuri, P.; Mandal, S.In the present work, gas sensing properties of the screen printed ceria and ruthenate-sensitized BaSnO3 (BSO) with La doping heterostructure sensors towards the detection of ammonia and formaldehyde gases at room temperature were studied. Adhered, porous screen printed films with different morphologies were obtained by depositing the LaxBa1?xSnO3?? (x = 0 and 0.05) powder particles prepared by the polymerized complex method. Ceria and ruthenate sensitization for screen printed LaxBa1?xSnO3?? (x = 0.05) film was processed through dip-coating in the 0.03 M aqueous solution of CeCl3 and RuCl3, respectively. La-doped BaSnO3 (LBSO) sensor with smaller crystallites, needle-like morphology and high concentration of oxygen vacancies exhibited superior gas response of 65 and 29 towards 50 ppm of ammonia and formaldehyde gases, respectively. Superabundant sensitization of ceria and ruthenate reduced the oxygen vacancy and structural open porosity in the LBSO sensor; therefore, the ammonia gas response was decreased from 65 to 14 and 3, respectively, whereas the formaldehyde gas response was reduced to less than 1/6th times the LBSO sensor. Limit of detection of LBSO sensors was estimated to be ~ 1 and ~ 2 ppm against ammonia and formaldehyde, respectively. The presence of fluorite structured phase ceria with high oxygen atoms storage capacity facilitates the rapid oxidization of analyte gases and caused the expeditious response (75 s) and recovery (60 s) in CeOx-sensitized LBSO sensor. This study might give a new insight into the development of doped and sensitized BSO-based gas sensors operating at ambient conditions. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.Item Ultra-sensitive clogging free combustible molecular precursor-based screen-printed ZnO sensors: a detection of ammonia and formaldehyde breath markers(Springer, 2021) Manjunath, G.; Pothukanuri, P.; Mandal, S.It is beneficial to develop the cost-effective, ultra-sensitive ZnO-based sensor for the rapid detection and quantification of the ammonia and formaldehyde breath markers under ambient conditions. Here, one-step solution route was adopted to formulate the aqueous combustible molecular precursor-based clogging free screen-printing ink consisting of zinc nitrate as an oxidizer, glycine as fuel, and eco-friendly binder sodium carboxymethylcellulose. The formulated precursor was deposited on the glass substrates via a screen-printing technique followed by annealing at different temperatures for an hour. Screen printed ZnO sensors processed at 500 °C with high crystallinity, less lattice distortion, low optical bandgap, and high concentration of donor defects showed remarkably high NH3 gas response ~ 336 and a moderate HCHO response ~ 16.4 towards the 5 ppm and 10 ppm of the respective gases. In addition it's LOD values is drawn as 0.6 ppm and 2.9 ppm for NH3 and HCHO gases, respectively, and exhibits superior selectivity towards ammonia. Faster diffusion of oxygen vacancies (Vo) in the smaller crystallites resulted expeditious sensor kinetics in the screen-printed sensor processed at 400 °C. Response and recovery time were recorded to be 50 s and 50 s to the 5 ppm of NH3, respectively. The crystallinity-dominant domain overcomes the adverse effect of larger grains on the gas response of screen-printed ZnO sensor processed at 500 °C. Robust, scalable, and cost-effective screen-printed ZnO conductometric sensors demonstrated here has a potential application in clinical diagnosis, and also in monitoring the NH3 and HCHO gases at low ppm-level. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.Item Visible light irradiated photocatalytic reduction of CO2 to hydrocarbons using hybrid polyaniline/ CuO nanocomposite in aqueous system(Taylor and Francis Ltd., 2022) Matthew, D.; Shetty K, V.The ever-increasing energy demand has resulted in an increase in CO2 emissions and global warming. Photocatalytic reduction of CO2 to methanol, which is considered to be the next generation alternate fuel is gaining interest to combat global warming and to move towards a methanol economy. The present work focuses on photocatalytic reduction of CO2 using Polyaniline/CuO (PANI/CuO) nanocomposite to methanol, formic acid, and formaldehyde under visible light irradiation. CuO nanoparticles were synthesised using the aqueous extract of Tectona grandis (teak) leaves and further used in the synthesis of PANI/CuO nanocomposite with different CuO loading. PANI/CuO nanocomposite exhibited visible light activity in the reduction of CO2 to form methanol, formic acid, and formaldehyde. Photocatalytic reduction of CO2 with PANI/CuO nanocomposite containing 13.7% by weight of CuO resulted in a maximum yield of methanol. The band gap energy of the nanocomposite was found to be 2.28 eV, thus confirming its good visible light activity and the PANI-CuO heterojunction-based mechanism of photocatalysis is proposed. The synthesis of PANI-CuO photocatalyst uses CuO which is synthesised by an eco-friendly route with the utilisation of teak leaves, a timber industry waste and thus it can serve as a greener catalyst. © 2022 Indian Institute of Chemical Engineers.Item Visible Light Mediated Photocatalytic Reduction of CO2 to Non-fossil Fuel and Valuable Products by Polyaniline-TiO2 Nanocomposites(Springer Science and Business Media Deutschland GmbH, 2022) Prabhu Teja, K.; Shetty K, V.CO2, a major contributor for global warming may be considered as a free source of carbon and can be converted into hydrocarbons. Mimicking the photosynthesis process that utilizes light energy to convert CO2, is the favorable option, and solar energy may be harnessed. The present paper reports the visible light mediated photocatalytic reduction of CO2 to formic acid, formaldehyde and methanol using Polyaniline-TiO2 nanocomposites (PANI-TiO2) in aqueous media under ambient conditions. The optimum TiO2 content in the nanocomposite to maximize the yield of formaldehyde and formic acid is 18.2% by weight, and it has a band gap of 2.81 eV. The yield of formaldehyde, formic acid and methanol obtained were 80.57, 32.17 and 6.3 μmole/g catalyst, respectively, in eight hours with 0.3 g/L catalyst loading. The catalyst loading of 0.7 g/L is the optimum loading to maximize the yield of formaldehyde and formic acid. Maximum yield of methanol was obtained with PANI-TiO2 containing 35% TiO2. This approach can lead the energy sector toward a non-fossil fuel-based economy. © 2022, King Fahd University of Petroleum & Minerals.