@article { ISI:000327052700035, title = {Oxidative dehydrogenation of ethyl benzene to styrene over hydrotalcite derived cerium containing mixed metal oxides}, journal = {Green Chemistry}, volume = {15}, number = {11}, year = {2013}, month = {SEP}, pages = {3259-3267}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Cerium containing mixed oxides derived from hydrotalcites was prepared and its catalytic activity was studied for oxidative dehydrogenation of ethyl benzene to styrene. Structural, spectroscopic and morphological features of the catalyst have been thoroughly examined with various physico-chemical characterization methods. Raman spectroscopy studies show evidence for oxygen vacancies in lower loadings of cerium which enhanced the oxygen migration. The transmission electron microscopy image showed good dispersion of ceria clusters on the mixed metal oxide. The catalytic activity results suggested that the conversion of ethyl benzene and styrene yield is stable for at least 12 hours without any significant catalyst deactivation. The styrene selectivity and ethyl benzene conversion were higher in a catalyst containing 0.03 mole percentage of cerium. Structural features of the spent catalysts have also been examined to demonstrate the stability of the catalyst during the reaction.

}, issn = {1463-9262}, doi = {10.1039/c3gc41321g}, author = {Venugopal, Ashok Kumar and Venugopalan, Aswathy Thareparambil and Kaliyappan, Periyasamy and Raja, Thirumalaiswamy} } @article { ISI:000344998100063, title = {Green chemistry approach to styrene from ethylbenzene and air on MnxTi1-xO2 catalyst}, journal = {RSC Advances}, volume = {4}, number = {100}, year = {2014}, month = {OCT}, pages = {57087-57097}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Styrene (ST) is an industrially important commodity chemical, and design of a suitable catalyst, which provides high ethyl benzene (EB) conversion and styrene selectivity at Lower temperature with sustainable activity, is one of the major challenges in the field of heterogeneous catalysis. Manganese incorporated in titania (MnxT1-xO2) anatase Lattice, prepared via the solution combustion method, was evaluated for oxidative dehydrogenation (ODH) of EB with O-2 or air. MnxTi1-xO2 catalysts were characterized by different physiochemical methods. Up to 15\% Mn could be introduced into the TiO2 Lattice. TEM and XRD indicate disordered mesoporosity, further confirmed by adsorption isotherm analysis. MnxTi1-xO2 catalysts were evaluated for ST synthesis from EB using air or oxygen as oxidant between 440 and 570 degrees C. Reaction conditions have been varied systematically, such as catalyst composition, and EB/air/O-2 flow. MnxTi1-xO2 shows sustainable 55\% styrene yield for 45 h without deactivation under optimum conditions. A thorough analysis of spent catalysts demonstrates the conversion of initial anatase phase MnxTi1-xO2 to Mn3O4 supported on the rutile (R) phase of TiO2. The above change occurs in the first few hours of reaction and the Mn3O4 on R-TiO2 phase is the active phase of the catalyst and responsible for sustainable activity for Longer duration.

}, issn = {2046-2069}, doi = {10.1039/c4ra11814f}, author = {Negi, Sanjay Singh and Venugopalan, Aswathy Thareparambil and Raja, Thirumalaiswamy and Singh, Anand Pal and Gopinath, Chinnakonda S.} } @article {42853, title = {Effective and selective oxidation of 2-butanol over Mn supported catalyst systems}, journal = {Applied Catalysis A-General}, volume = {525}, year = {2016}, month = {SEP}, pages = {237-246}, abstract = {

Oxidation of alcohols to their corresponding aldehydes/ketones is an important reaction in industries as well as in academic perspective. Selective oxidation (Selox) of alcohols like methanol, ethanol and propanol are well studied in literature; however, alcohols like butanol, pentanol, octanol is a challenging task. Selective oxidation of 2-butanol to methyl ethyl ketone (MEK) is an important reaction due to its wide range of applications. Herein, we demonstrated the selective oxidation of 2-butanol to MEK over Mn supported on different oxide supports. A series of MnxOy-Al2O3 (MA), MnxOy-CeO2 (MC), MnxOy-ZrO2 (MZ) and MnxOy-SiO2 (MS) catalysts were prepared by co-precipitation followed by hydrothermal method. As synthesised catalysts were characterised by various physico-chemical characterisation techniques. It was found that the presence of Mn3O4 species in MA and MZ catalysts is responsible for maximum catalytic activity towards 2-butanol oxidation. MA catalyst conferred a maximum 2-butanol conversion of 51\% and 88\% selectivity towards MEK. XPS analysis revealed that Mn in MA catalyst exists in +2 and +3 oxidation states and responsible for 2-butanol oxidation. Moreover it was found that the acidity of the catalyst also plays an important role in catalytic activity. (C) 2016 Published by Elsevier B.V.

}, doi = {10.1016/j.apcata.2016.08.005}, author = {Prabu, Kandasamy and Prabu, Marimuthu and Venugopal, Ashok Kumar and Venugopalan, Aswathy Thareparambil and Sandilya, W. V. Y. Sai and Gopinath, Chinnakonda S. and Raja, Thirumalaiswamy} } @article {47310, title = {Highly efficient and reusable Ru-NaY catalyst for the base free oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic acid}, journal = {Catalysis Today}, volume = {375}, year = {2021}, month = {SEP}, type = {Article}, abstract = {

Oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is an important reaction for the production of recyclable bio-based polymers. Herein, we report a series of Ru nanoparticles supported on NaY zeolites catalysts for the oxidation of HMF to FDCA. The catalysts were prepared by simple ion exchanged method. Among all the catalysts, the optimized 3 wt \% Ru-NaY catalyst showed superior catalytic activity under base free conditions with a shorter period of reaction time. The conversion of HMF was 100 \% with 94 \% FDCA yield. This catalyst was reused for fourth cycles, with an insignificant decrease in the yield of FDCA. H2-chemisorption and HRTEM studies confirmed that high metal dispersion and small size of Ru nanoparticles play vital roles for the HMF oxidation. In addition, the acidic hydroxyl groups of the supercage as well as higher amount of metallic Ru{\textdegree} are also responsible for the high yield and productivity of FDCA.

}, doi = {10.1016/j.cattod.2020.05.009}, author = {Kandasamy, Prabu and Gogoi, Pranjal and Venugopalan, Aswathy Thareparambil and Raja, Thirumalaiswamy} } @article {47094, title = {Promoted mesoporous Fe-alumina catalysts for the non-oxidative dehydrogenation of isobutane}, journal = {Catalysis Communications}, volume = {150}, year = {2021}, month = {FEB}, pages = {106263}, type = {Article}, abstract = {

Production of isobutene is commercially consequential and highly demanding from the end-use industries being a key platform molecule as well as an intermediate for a variety of value-added chemicals. Traditionally, isobutene is prepared via steam cracking and fluid catalytic cracking methods. However, the catalysts used in these conventional methods have disadvantages like coke formation, sintering, etc. In this study, the catalytic non-oxidative dehydrogenation of isobutane over acidic, alkaline, and noble metal promoted mesoporous iron-doped catalysts was investigated. Iron doping has a significant function in controlling isobutene selectivity. The synthesis method is crucial to achieve successful metal doping in the mesoporous alumina matrix. Promoted catalysts exhibited a notable difference in isobutane conversion with a marginal change in dehydrogenation selectivity. Silver promoted catalyst showed slightly higher isobutene yield due to the optimal catalytic properties. This catalyst was stable for a considerable duration, and coke deposition, as well as particle agglomeration, were observed to faintly inhibit the catalytic activity.

}, keywords = {iron, Isobutane, Isobutene, Mesoporous alumina, Non-oxidative dehydrogenation}, issn = {1566-7367}, doi = {10.1016/j.catcom.2020.106263}, author = {Venugopalan, Aswathy Thareparambil and Kandasamy, Prabu and Gupta, Nikitra Nihalchand and Thirumalaiswamy, Raja} } @article {49313, title = {New insights into the composition and catalytic performance of VOx-Ga/γ-Al2O3 for the oxidative dehydrogenation of propane to propene}, journal = {New Journal of Chemistry}, volume = {48}, year = {2024}, month = {AUG }, pages = {15077-15087}, type = {Article}, abstract = {

Oxidative dehydrogenation (ODH) of propane is a promising alternative route for propene production. In this work, we developed a series of vanadium and gallium oxides supported on gamma-Al2O3 catalysts by an incipient wetness impregnation method. Among the employed catalysts, the VGA-2 showed superior catalytic activity, and the catalyst was demonstrated for longevity in ODH of propane with a stable activity using a continuous flow fixed bed reactor at 400 degrees C. H-2-TPR and UV-visible spectra showed the presence of highly dispersed monomeric VOx species with tetrahedral coordination geometry, which influences product selectivity. The characterization results also conferred that the redox nature of vanadium (V5+ and V4+) oxide and higher V5+ content on the surface of the VGA-2 catalysts are more favourable for C-H activation. In addition, the pyridine-FTIR and Ga-71 solid-state NMR studies further substantiated the presence of Lewis acid sites and tetrahedrally coordinated Ga3+Ox species that are highly responsible for the ODHP activity, respectively. Furthermore, in situ-DRIFTS studies conferred that the propane adsorption at ambient temperature showed the formation of intermediate propoxide species with the evolution of sigma-bonds and with further increase in the temperature to 325 degrees C; the stretching vibrations of the =C-H and -C-H bonds in the propylene molecule were observed. The spent catalysts were also analyzed by thermogravimetric analysis, where the optimized catalyst (VGA-2) showed the least coke deposition.

}, issn = {1144-0546}, doi = {10.1039/d3nj05109a}, author = {Kandasamy, Prabu and Gawali, Sheetal and Venugopalan, Aswathy Thareparambil and Manikandan, Marimuthu and Mekala, Siva Prasad and Shelke, Ankita and Ajithkumar, Thalasseril G. and Bhatte, Kushal and Raja, Thirumalaiswamy} }