@article { ISI:000260978000009, title = {Heteropoly acid-based supported ionic liquid-phase catalyst for the selective oxidation of alcohols}, journal = {Journal of Catalysis}, volume = {259}, number = {2}, year = {2008}, month = {OCT}, pages = {232-239}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, type = {Article}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

A supported ionic liquid strategy has been applied for the immobilization of a heteropolyacid, molybdovanadophosphoric acid, onto ionic liquid-modified mesoporous silica SBA-15. The immobilized catalyst demonstrated high activity in the aerobic oxidation of primary and secondary alcohols to aldehydes and ketones, respectively. No overoxidation of the primary alcohols to carboxylic acids was observed. Secondary alcohols were chemoselectively oxidized to ketones in the presence of primary alcohol, hetero atom, and allyl groups. This catalyst could be recycled five times without obvious loss of activity. (C) 2008 Elsevier Inc. All rights reserved.

}, keywords = {Air as an oxidant, Mesoporous silica SBA-15, Molybdovanadophosphoric acid, Selective oxidation, Supported ionic liquid}, issn = {0021-9517}, doi = {10.1016/j.jcat.2008.08.010}, author = {Bordoloi, Ankur and Sahoo, Suman and Lefebvre, F. and Halligudi, Shivaraj B.} } @article { ISI:000252563300006, title = {Selective oxidation of ethane over Mo-V-Al-O oxide catalysts: insight to the factors affecting the selectivity of ethylene and acetic acid and structure-activity correlation studies}, journal = {Catalysis Letters}, volume = {121}, number = {1-2}, year = {2008}, month = {FEB}, pages = {39-51}, publisher = {SPRINGER}, address = {233 SPRING STREET, NEW YORK, NY 10013 USA}, abstract = {

Catalysts of general formula, MoVAlOx were prepared with the initial elemental composition of 1:0.34:0.167 (Mo:V:Al) at a pH value in the range of 1-4. The elemental analysis showed that the final composition of the catalysts is pH dependant. The performance of the catalysts was tested for selective oxidation of ethane to give ethylene and acetic acid. While all of them were active for ethane oxidation with a moderate conversion, the catalyst prepared at pH 2 showed a highest activity with 23\% ethane conversion and a combined selectivity of 80.6\% to ethylene and acetic acid. The catalyst prepared at pH 4 was least selective to ethylene and acetic acid. Various techniques like powder XRD, SEM, Raman, UV-Vis and EPR were used to characterize the catalysts and to identify the active phases responsible for the selective oxidation of ethane. The powder XRD data showed that the catalysts prepared at pH 1 and 2 contain mainly of MoO3 and MoV2O8 along with traces of Mo4O11. The amount of MoO3 was slightly higher in the catalyst prepared at pH 1. However, the catalyst prepared at pH 3 contains mainly of MoV2O8 with no trace of MoO3. The catalyst prepared at pH 4 showed V2O5 as the major phase along with MoVAlO4 phase. The Raman data corroborated the XRD results. EPR and UV-Vis studies indicated the presence of traces of V-4 in pH 1 and 2 catalysts and significant amount of Mo5+ in all the catalysts. Thus, the high activity and selectivity to ethylene and acetic acid are attributed to the presence of MoV2O8 phase and other reduced species like Mo4O11 phase supported on MoO3. The presence of V and Mo ions in a partially reduced form seems to play a crucial role in the selective oxidation of ethane.

}, keywords = {Acetic acid, ethane, Ethylene, mixed metal oxide, Selective oxidation}, issn = {1011-372X}, doi = {10.1007/s10562-007-9289-0}, author = {Sankaranarayanan, T. M. and Ingle, Rohit H. and Gaikwad, T. B. and Lokhande, S. K. and Raja, T. and Devi, R. N. and Ramaswamy, V. and Manikandan, Palanichamy} } @article { ISI:000264437500002, title = {Selective oxidations over zeolite- and mesoporous silica-based catalysts: selected examples}, journal = {Catalysis Today}, volume = {141}, number = {1-2}, year = {2009}, note = {18th National Symposium and Indo-US Seminar on Catalysis, Indian Inst Petroleum, Dehradun, INDIA, APR 16-18, 2007}, month = {MAR}, pages = {3-11}, publisher = {Catalysis Soc India; Petrotech Soc; Indo US Sci \& Technol Forum}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Selective oxidation of hydrocarbons/terpenes in the liquid phase are reported over three categories of zeolite- and mesoporous silica-based catalysts: (1) transition metal complexes (metal phthalocyanines, copper acetate dimers and Co/Mn acetate trimer) encapsulated in zeolite-Y, (2) transition metal complexes (Mn-Salen), grafted on SBA-15, and (3) transition metal ions in framework positions of zeolites and mesoporous molecular sieves like Ti-silicates. Upon heterogenization, the metal complexes exhibited enhanced catalytic acitivity/selectivity. The causes for the enhanced catalytic activity/product selectivity have been explored. Dimer formation (copper acetate) or geometric distortion in the zeolite cavities (metal phthalocyanines) and consequent changes in energy levels and redox potentials are shown to modify the catalytic activity (in the selective oxidation of hydrocarbons) of the encapsulated metal complexes. In the case of Mn-Salen grafted on SBA-15, increasing the acidity of the siliceous surface (by -SO(3)H groups, for example) leads to a more facile reduction of the Mn ions and, thereby, enhanced catalytic activity in the selective epoxidation of limonene. When Ti ions are introduced in framework positions, reactive metal-oxo species are formed on contact with H(2)O(2) or O(2), Which influence the mode of O-O cleavage (heterolytic/homolytic) and product selectivity. The structure-function relationships in these catalysts are reported. (c) 2008 Elsevier B.V. All rights reserved.

}, keywords = {Mn-Salen, Oxidation of hydrocarbons and limonene, Reactive oxo species, Selective oxidation, Titanosilicates, Zeolite-encapsulated metal complexes}, issn = {0920-5861}, doi = {10.1016/j.cattod.2008.03.009}, author = {Ratnasamy, Paul and Srinivas, Darbha} } @article { ISI:000287996100027, title = {Selective catalytic oxidation of geraniol to citral with molecular oxygen in supercritical carbon dioxide}, journal = {Applied Catalysis A-General}, volume = {394}, number = {1-2}, year = {2011}, month = {FEB}, pages = {209-214}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Selective catalytic oxidation of geraniol to citral with molecular oxygen in supercritical carbon dioxide (scCO(2)) has been investigated. The catalyst used was a chromium containing mesoporous molecular sieve catalyst viz. CrMCM-41. Comparison studies were performed with CoMCM-41. PtMCM-41 and PdMCM-41 catalysts. Among the various catalysts studied. CrMCM-41 showed a high conversion of geraniol and an excellent selectivity for citral. In contrast CoMCM-41, PtMCM-41 and PdMCM-41 catalysts exhibited low conversion of geraniol. However all three catalysts compared showed similar citral selectivity to CrMCM-41. The effect of CO(2) pressure and reaction temperature geraniol oxidation was studied with CrMCM-41. Supercritical CO(2) medium was found to enhance the conversion of geraniol and/or yield of citral. It was noticed that the catalyst can be recycled with negligible loss of conversion. (C) 2011 Elsevier B.V. All rights reserved.

}, keywords = {Citral, Geraniol, heterogeneous catalyst, Molecular oxygen, Selective oxidation, Supercritical carbon dioxide}, issn = {0926-860X}, doi = {10.1016/j.apcata.2011.01.001}, author = {Dapurkar, Sudhir E. and Kawanami, Hajime and Chatterjee, Maya and Rode, Chandrasekhar V. and Yokoyama, Toshirou and Ikushima, Yutaka} } @article { ISI:000311350000009, title = {Selective oxidation of cyclic olefins over framework Ti-substituted, three-dimensional, mesoporous Ti-SBA-12 and Ti-SBA-16 molecular sieves}, journal = {Catalysis Today}, volume = {198}, number = {1, SI}, year = {2012}, month = {DEC}, pages = {59-68}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Framework Ti-substituted, three-dimensional, mesoporous titanosilicates, Ti-SBA-12 and Ti-SBA-16, were prepared by direct hydrothermal synthesis method. These catalysts showed catalytic activity higher than the hitherto known titanosilicates for the oxidation of cyclic olefins (cyclohexene and cyclooctene) with tert.-butyl hydroperoxide. An epoxide selectivity of 100\% and olefin conversion greater than 92\% were obtained. Cubic Ti-SBA-16 with interconnected cage-like mesopore structure was more active than hexagonal Ti-SBA-12. X-ray diffraction and diffuse reflectance UV-vis, Fourier transform infrared, Raman and electron paramagnetic resonance spectroscopies provided evidence for the substitution of Ti4+ (for Si4+) in the framework locations. The catalytic activity correlated with the concentration of framework-substituted, tetrahedral Ti4+ ions. Easy accessibility of the active sites and the three-dimensional mesoporous structure are the possible causes for the superior activity of these titanosilicate catalysts. (C) 2012 Elsevier B. V. All rights reserved.

}, keywords = {Epoxidation of cyclic olefins, mesoporous materials, Molecular sieves, Selective oxidation, Ti-SBA-12, Ti-SBA-16, Titanosilicates}, issn = {0920-5861}, doi = {10.1016/j.cattod.2012.01.035}, author = {Kumar, Anuj and Srinivas, Darbha} } @article {48768, title = {Selective oxidation of 5-HMF to DFF over alkali promoted Mn nanocomposite}, journal = {Applied Catalysis A-General}, volume = {659}, year = {2023}, month = {JUN}, pages = {119180}, type = {Article}, abstract = {

Various compositions of Cs promoted Mn catalysts were synthesized and investigated for selective oxidation of 5HMF to DFF, among which Mn-Cs(80:20) was found to be most efficient giving 91 \% conversion of 5-HMF and 99 \% selectivity to DFF. Detail characterization like N2-sorption, BET surface area, TG-DTA, XRD, XPS, FE-SEM-EDX, TEM, HR-TEM, CO2-TPD, H2-TPR, O2-TPO, FTIR, Raman spectra and CH3OH-IR were done to establish structureactivity correlation. Enhanced surface area, porosity, thermal stability, dual morphologies were observed due to inclusion of Cs in Mn lattice domain which further enhanced the crystallinity, and oxygen diffusion on the surface. Mixed morphologies comprising nanoparticles (4-5 nm) and nanocubes (50-60 nm) were observed with enhanced redox potential and reduced work function due to weakening of Mn-O bonds. Significant increase in the basicity of catalyst, interfacial redox properties and lattice oxygen led to highly efficient oxidation of 5-HMF to DFF via Mars-van Krevelen mechanism at relatively milder conditions i.e. T = 90 degrees C and PO2= 200 psig. The catalyst was easily recyclable up to 7 times with minor loss in activity which was regenerated heat treatment protocol.

}, keywords = {5-HMF, Biomass, heterogeneous catalyst, polyurethane, Selective oxidation}, issn = {0926-860X}, doi = {10.1016/j.apcata.2023.119180}, author = {Solanki, Bhanupratap Singh and Roh, Hyun-Seog and V. Rode, Chandrashekhar} }