Faculty Publications
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Item The hydrogen peroxide-mediated oxidation of biorenewable furfural to 2(5H)-furanone using heteropolyacids supported on ammonium y zeolite as the catalyst(Elsevier Ltd, 2020) Tiwari, R.; Bhat, N.S.; Mal, S.S.; Dutta, S.A series of heteropolyacid supported on ammonium Y zeolite (HPA-NH4YZ) catalysts were prepared and used for the catalytic oxidation of furfural to 2(5H)-furanone in aqueous hydrogen peroxide. The catalysts were characterized by PXRD, FTIR, TGA, and SEM analyses. The organic-solvent-free reaction was optimized on temperature, duration, loading of catalyst, and the equivalent of H2O2. The 20%PTA-NH4YZ catalyst showed the best catalytic activity giving 2(5H)-furanone in 40% isolated yield by solvent extraction under optimized conditions (20wt% cat., 100°C, 90min, 7.5eq. 30%H2O2). In addition, around 20% of succinic acid was recovered from the aqueous layer. © 2020 Elsevier Ltd. All rights reserved.Item A Liquid Derivative of Phosphotungstic Acid as Catalyst for Benzyl Alcohol Oxidation in Water: Facile Separation and Stability of Benzaldehyde at Room Temperature†(Wiley-Blackwell, 2017) Bhattacharjee, R.R.; Thangamani, S.; Mal, S.S.Polyetheramines belong to a class of green di-block copolymer with ethylene oxide and propylene oxide moieties along with terminal amine functionality. The polymers are biocompatible and show temperature dependant phase separation properties. Herein, we report the effect of a polyetheramine (Jeffamine®) on the catalytic properties of a well studied polyoxometalate catalysts, phosphotungstic acid (PTA). The catalytic reaction chosen for the test is the hydrogen peroxide-mediated oxidation of benzyl alcohol (BzOH). Modification of PTA with Jeffamine® (PTA-Jeffamine®) resulted in a solvent-less liquid-like material accessible to a wide range of solvents. The PTA-Jeffamine® catalyst was observed to enhance the conversion of BzOH compared to that of pristine PTA and facilitated easy separation of benzaldehyde (BzH) and catalyst from reaction mixture. Stability of synthesized BzH was studied with gas chromatography attached with mass spectrometry (GC-MS). Synthesis of the catalyst is cost-effective and scalable due to easy availability of the individual components and nature of the synthetic protocol. UV-visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM) were used to characterize the catalyst. Surface tension experiment, FE-SEM, ICP-MS and controlled experiments were performed to understand the effect of Jeffamine® in the catalytic process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimItem Novel strategies for glucose production from biomass using heteropoly acid catalyst(Elsevier Ltd, 2020) Nayak, A.; Pulidindi, I.N.; Sankar Rao, C.S.Bioethanol and direct glucose fuel cells pledged clean energy to the world. Cellulose depolymerization for glucose production has been a successful approach in bioethanol production. Heteropoly acids (HPAs) are strong Brønsted solid acid catalysts for biomass hydrolysis. Keggin type HPAs, namely, Silicotungstic acid (HSiW), Phosphotungstic acid (HPW), and Phosphomolybdic acid (HPMo), were used for the hydrolysis of lignocellulosic biomass to glucose. Five different biomass feedstocks, namely, miscanthus, sugarcane leaves, switchgrass, sunflower seeds, and bamboo leaves, were examined for the feasibility of total reducing sugar (TRS) yield through the composition analysis and catalytic biomass hydrolysis. Sunflower seeds contained the maximum holocellulose with 90.6%, and switchgrass contained the least i.e., 77.63%. Among the five biomass tested, switchgrass resulted in the highest TRS (5.77 wt/dry wt. %) with HPMo catalyst at a catalyst to biomass ratio of 30:100 (wt./wt. %), a reaction temperature of 120 °C for 3 h. The reaction parameters for depolymerization were optimized for all three HPAs, and the optimized conditions were 3 h and 120 °C. HPMo showed maximum TRS yield (5.77 wt/dry wt.%) among the three HPAs at 30:100 catalyst to biomass ratio. However, a catalyst to biomass ratio of 20:100 (wt./wt.%) was economical (5.25 wt/dry wt.%) for commercial application. © 2020 Elsevier LtdItem Selective dehydration of 1-butanol to butenes over silica supported heteropolyacid catalysts: Mechanistic aspect(Elsevier B.V., 2021) Kella, T.; Vennathan, A.A.; Dutta, S.; Mal, S.; Shee, D.Butenes are considered as important olefinic building block to produce fuels/fuel additives and commodity chemicals. In the present investigation, selective dehydration of 1-butanol to butenes was studied in a continuous-flow fixed-bed reactor using various silica-supported heteropolyacid (HPA) catalysts such as phosphotungstic acid (PTA), silicotungstic acid (STA), phosphomolybdic acid (PMA), and silicomolybdic acid (SMA) as the solid acid catalysts. The physicochemical properties of these HPA were determined by BET, powder XRD, FTIR, NH3-TPD, and Py-FTIR. The acid strength and Brønsted/Lewis (B/L) acid ratio were increased with higher loading of HPA on silica. The nature of HPA (addenda and hetero atom) and loading of HPA are important factors for the dehydration of 1-butanol and selectivity towards butenes. PTA and STA showed superior catalytic activity than PMA and SMA. The reaction temperature and WHSV also strongly affected the butanol conversion and selectivity of butenes. The selectivity of di-n?butyl ether decreases with the rising temperature from 523 K to 623 K. The isomerization of 1-butene leading to the formation of other butene isomers depends on the HPA loading, temperature, and WHSV. The presence of molybdenum addendum atom in PMA and SMA promotes dehydrogenation and hydrogenation, leading to the formation of various light hydrocarbons. The 20PTA/SiO2 catalyst afforded 99.8% selectivity towards butenes at quantitative conversion of 1-butanol, whereas the 20STA/SiO2 catalyst gave nearly 97.0% conversion of 1-butanol and 99.9% butenes selectivity at 673 K, 37.4 h?1 of WHSV. © 2021Item Synergistic Enhancement of Supercapacitor Performance: Vanadium-Substituted Phosphotungstic and Molybdic Acid Combined with Polypyrrole Using Pyridinium and Ammonium Ionic Containing Organic Cation Linkers with Improved Conductivity(John Wiley and Sons Inc, 2024) Puniyanikkottil, M.A.; Chandewar, P.R.; Shee, D.; Mal, S.S.High-performance energy-storage devices have emerged as a favored choice owing to their remarkable efficiency, sustainability, and environmental friendliness. Nowadays, polyoxometalate (POM)-based supercapacitor (SC) electrode materials have gained much attention. Herein, a few new POMs and ionic liquid (IL) composites incorporated into conducting polymer as electrode materials for SC applications are reported. The H6[PV3Mo9O40]⋅34H2O (PV3Mo9) and H6[PV3W9O40].34H2O (PV3W9) POMs are treated with tetrabutylammonium chloride and 1-butyl-4-methyl pyridinium chloride (BMP) and finally combined with polypyrrole (PPy) for the SC studies. An extensive array of analytical techniques is employed to delve into the interplay between the constituents within the composite materials, such as Fourier transform infrared spectroscopy, powder X-ray diffraction, thermogravimetric analysis, nuclear magnetic resonance (1H and 13C), Field-emission scanning electron microscopy, energy-dispersive X-ray stpectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area. The combined application of these techniques enables us to understand the interaction dynamics within composite materials comprehensively. POM–ILs combination improves the solubility issues of POMs, and doping of PPy enhances the electrochemical performances of the materials. The PV3W9–BMP–PPy symmetric SC cell shows a specific capacitance of 294.79 F g−1 and an energy density of 28.89 Wh kg−1 at 1 A g−1 current density in 0.25 M H2SO4 medium followed by an excellent cycle life of 78.6% after 10,000 galvanostatic charge–discharge cycles. The fabricated SC device is performed to light up the bulbs of red, yellow, and green light emitting diodes for 50, 30, and 28 s, respectively. © 2024 Wiley-VCH GmbH.Item Catalytic Synthesis of Xanthene and Unprecedented Evolution of Naphthopyrans Using Heteropoly Acid-Tantalum(V) Oxide Hybrid Composite as Promoter(John Wiley and Sons Inc, 2025) Mahapatra, J.; Dastidar, S.G.; Jagankar, D.; Roy, N.; Sharma, J.; Mukherjee, A.; Maity, C.; Panda, T.K.; Mal, S.S.Xanthene derivatives are prepared by using tantalum(V) oxide (Ta2O5)-supported heteropoly acid (HPA), Keggin 12-phosphotungstic acid (PTA)-based heterogeneous catalyst PTA@Ta2O5 under neat conditions. The composite is prepared by the wetness impregnation method and is characterized by various techniques. Under optimized conditions, xanthenes are synthesized with prominent yields in remarkably short reaction times. The green chemistry metrics are appraised for the xanthene reaction. Surprisingly, a few novel naphthopyran derivatives are isolated instead of the conventional xanthene derivatives when cinnamaldehyde analogous are introduced under the same reaction protocol. Unprecedented naphtho[2,1-b]pyran-type derivatives of 3m, 3n, and 3o are isolated, depending on the specific substituted cinnamaldehyde used, and interestingly, the nature of the substituent in cinnamaldehyde decides the different reaction pathways leading to the formation of respective pyrans. Diverse possible mechanisms are encountered with the PTA@Ta2O5 catalyst based on the respective transformations. The solid-state structures of xanthenes and naphthopyrans are thoroughly investigated. Furthermore, some derivatives are studied in vitro to assess their antimicrobial activity, and the findings are compared with those of reference standard antibiotics. © 2025 Wiley-VCH GmbH.