@article { ISI:000232815700010, title = {Formation of nanosized zirconia-supported 12-tungstophosphoric acid in mesoporous silica SBA-15: a stable and versatile solid acid catalyst for benzylation of phenol}, journal = {Journal of Catalysis}, volume = {235}, number = {2}, year = {2005}, month = {OCT}, pages = {341-352}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, type = {Article}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

A nanosized zirconia-supported 12-tungstophosphoric acid (TPA) in SBA-15 composite was prepared by wet impregnation of TPA/ZrO2 nanoparticles inside the mesoporous channels of SBA-15. The resulting composite material was calcined at 1123 K and characterized by elemental analysis, powder X-ray diffraction, nitrogen adsorption isotherms, transmission electron microscopy (TEM), scanning electron microscopy (SEM), solid-state P-31 CP-MAS NMR, Si-29 MAS NMR, UV-vis diffuse reflectance spectra, FTIR, TPD of ammonia, FTIR pyridine adsorption, and thermogravimetric analysis (TG-DTG). The synthesized TPA/ZrO2/SBA-15 showed a well-ordered hexagonal inesoporous structure and mesoporous support SBA-15 stabilized ZrO2-t (tetragonal) phase with crystal size in the range of 3-4 nm. SBA-15 was a better support than MCM-41 and MCM-48 because it retained its mesostructure even after high TPA loading and high calcination temperatures. Mesoporous silica support plays an important role in stabilizing the catalytically active tetragonal phase of zirconia, which gave the most active catalysts. The catalysts were examined for their catalytic activities in the liquid phase benzylation of phenol with benzyl alcohol and the catalyst 15 wt\% TPA/ 22.4 wt\% ZrO2/SBA-15 calcined at 1123 K was found to have high acidity and to be 10 times more active than neat TPA/ZrO2 Under the reaction conditions studied in benzylation of phenol. (c) 2005 Elsevier Inc. All rights reserved.

}, keywords = {nanosized, phenol benzylation reaction, terragonal phase, TPA/ZrO2}, issn = {0021-9517}, doi = {10.1016/j.jcat.2005.08.010}, author = {Sawant, D. P. and Vinu, A. and Jacob, Nalini E. and Lefebvre, F. and Halligudi, Shivappa B.} } @article { ISI:000226532100001, title = {Synthesis, characterization and photo catalytic degradation of aqueous eosin over Cr containing Ti/MCM-41 and SiO2-TiO2 catalysts using visible light}, journal = {Journal of Molecular Catalysis A - Chemical}, volume = {226}, number = {2}, year = {2005}, month = {FEB}, pages = {149-154}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Two series of samples were prepared namely Cr-Ti/MCM-41 and Cr/SiO2-TiO2 keeping Si/Ti mole ratio same, with different Cr loading. The physico-chemical properties of the samples were characterized by different analytical techniques such as XRD, FTIR, TEM, low temperature N-2 sorption, and UV-vis diffused reflectance spectroscopy. The impregnated TiO2 was in anatase form. The crystallite size was determined from Scherrer equation as well as by TEM. There is a difference between the shapes of nitrogen adsorption isotherms with and without Cr-loaded Ti/MCM-41 samples. The rate of nitrogen adsorption was found to increase with decrease in Cr content at lower P/P-0 for Cr-Ti/MCM-41 samples due to the blocking of the pores with Cr. All MCM-41 samples exhibited pore sizes from 24 nm to 32 nm. UV-vis diffused reflectance spectra of all Cr-loaded samples showed red shift of their absorption edges. Photo degradation of eosin dye was studied using visible light. (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {Cr-Ti/MCM-41, Cr/SiO2-TiO2, eosin, photo degradation, visible light}, issn = {1381-1169}, doi = {10.1016/j.molcata.2004.09.055}, author = {Awate, S. V. and Jacob, Nalini E. and Deshpande, Suvarna S. and Gaydhankar, T. R. and Belhekar, Anagha A.} } @article { ISI:000230123500009, title = {Thermal degradation kinetics of polyesters containing mesogenic aromatic diols}, journal = {Journal Applied Polymer Science}, volume = {97}, number = {3}, year = {2005}, month = {AUG}, pages = {784-792}, publisher = {JOHN WILEY \& SONS INC}, type = {Article}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

A series of polyesters were synthesized by reacting structurally differing aromatic diols with either saturated (flexible) or unsaturated (rigid) dicarboxylic acid halide by a stirred interfacial polycondensation technique. Thermal degradation kinetics of these polyesters were investigated by applying Coats-Redfern and Horowitz-Metzger nonisothermal procedures. The dynamic thermogravimetry experiments were conducted in nitrogen to obtain differential thermogravimetric plots. Thermal stability of these polyesters was discussed on the basis of semiquantitative methods such as differential procedural decomposition temperature, integral procedural decomposition temperature, and fraction decomposition temperature (e.g., 10 \% DT). Degradation proceeded in multiple stages. The thermal degradation patterns and activation energies in these stages were discussed in relation to central bridging moieties of aromatic diol. The activation energies of these polyesters were found to be in the range of 100 to 200 kJ/mol. The effect of spacer type on activation energy was also reported. (c) 2005 Wiley Periodicals, Inc.

}, keywords = {Activation energy, Degradation, kinetics (polym.), Polycondensation, polyesters}, issn = {0021-8995}, doi = {10.1002/app.21587}, author = {Mule, Smita Atmaram and Ghadage, R. S. and Jacob, Nalini E. and Rajan, C. R. and Ponrathnam, Surendra} } @article { ISI:000240521800008, title = {Adsorption of methanol on Si(100)/SiO(2)and mesoporous SBA-15}, journal = {Colloids and Surfaces A-Physicochemical and Engineering Aspects}, volume = {287}, number = {1-3}, year = {2006}, month = {SEP}, pages = {51-58}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Adsorption of methanol on SiO(100)/SiO2 substrate and mesoporous SBA-15 has been studied by using Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). Contact angle technique is employed to study the adsorption kinetics of methanol on SiO(100)/SiO2 and thermal stability of adlayer. Thermogravimetric (TGA) technique is used to understand the thermal behavior of methanol layer on SBA-15. Adsorption kinetics fit fairly well with Langmuir isotherms giving adsorption rate constant, k(a) = 0.0021 W s(-1). FTIR results show formation of methoxy silicon (SiOCHA silicon polyhydride (SiH2), carboxylate, molecular water and hydroxyl groups on Si(100)/SiO2 surface and only methoxy silicon on SBA-15. XPS results confirm methanol adsorption and support FTIR results. The methanol adlayers are found to be thermally stable up to a temperature of similar to 262 degrees C on both Si(100)/SiO2 and SBA-15 and decompose between 262 and 450 degrees C. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Adsorption, desorption, kinetics, Methanol, SBA-15, Si(100)/SiO2, thermal stability}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2006.03.021}, author = {Mirji, S. A. and Halligudi, Shivaraj B. and Mathew, Nevin T. and Ravi, V. and Jacob, Nalini E. and Patil, K. R.} } @article { ISI:000237835100010, title = {Adsorption of octadecyltrichlorosilane on mesoporous SBA-15}, journal = {Applied Surface Science}, volume = {252}, number = {12}, year = {2006}, month = {APR}, pages = {4097-4103}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Adsorption of octadecyltrichlorosilane (OTS) on mesoporous SBA-15 has been studied by using Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermo-gravimetric analysis (TGA) techniques. BET surface area analysis shows decrease of surface area from 930 to 416 m(2)/g after OTS adsorption. SEM pictures show close attachment of SBA-15 particles. EDAX measurements show increase of carbon weight percentage and decrease of oxygen and silicon weight percentage. XPS results closely support EDAX analysis. FTIR spectra shows presence of methyl (-CH3) and methylene (-CH2) bands and oriented OTS monolayer on SBA-15. Thermo-gravimetric analysis shows that the OTS adsorbed on SBA-15 are stable up to a temperature of 230 degrees C and that the OTS monolayers decompose between 230 and 400 degrees C. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Adsorption, OTS, SBA-15, Self-assembly, thermal stability}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2005.06.009}, author = {Mirji, S. A. and Halligudi, Shivaraj B. and Sawant, Dhanashri P. and Jacob, Nalini E. and Patil, K. R. and Gaikwad, A. B. and Pradhan, S. D.} } @article { ISI:000241306300002, title = {Claisen rearrangement of allyl phenyl ether over zeolites beta, mordenite and Y}, journal = {Microporous and Mesoporous Materials}, volume = {95}, number = {1-3}, year = {2006}, month = {OCT}, pages = {8-16}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The Claisen rearrangement of allyl phenyl ether (APE) to o-allylphenol was investigated over zeolites beta (BEA), mordenite (MOR) and Y (FAU) with different Si/Al ratios. Over the zeolite catalysts, the allylphenol cyclized to produce 2,3-dihydro-2-methyl benzofuran. Larger catalyst loading, higher reaction temperatures and longer run duration favored the formation of the ring compound. Conversion was small over MOR and FAU although they possessed higher acidity (as measured by the temperature programmed desorption of ammonia) compared to BEA. Studies using BEA revealed that the nature of the solvent influenced the reaction rate. The order of reactivity in the solvents was, benzene \> EDC (1,2-dichloroethane) \> toluene \> TCE (1, 1,2,2-tetrachloroethane) \>\> ACN (acetonitrile). The intermediate allylphenol reacted with the aromatic solvents to produce byproducts when benzene and toluene were used as solvents. A kinetic analysis assuming first order series and parallel reactions is presented. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {allyl phenyl ether, allylphenol, Benzofuran, Claisen rearrangement, zeolites}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2006.05.001}, author = {Wagholikar, S. G. and Mayadevi, S. and Jacob, Nalini E. and Sivasanker, S.} } @article { ISI:000236922600002, title = {Room temperature synthesis of mesoporous aggregates of anatase TiO2 nanoparticles}, journal = {Materials Chemistry and Physics}, volume = {97}, number = {2-3}, year = {2006}, month = {JUN}, pages = {207-212}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The controlled hydrolysis reaction of titanium tetrabutoxide in presence of acetic acid in isopropanol, i.e. in non-aqueous media was adopted in the present work for the synthesis of nanocrystalline titania followed by aging at ambient conditions for longer duration. The powder XRD shows that the as-dried precursor (without any aging) is non-crystalline in nature. However, room temperature aging for longer duration \> 120 days not only helped to develop crystallinity in TiO2 nanoparticles but also led to the formation of their self-assembly towards mesoporous aggregates creating sponge like TiO2 nano-structure having high surface area similar to 250m (2) g(-1)and narrow pore size distribution of 4-5 nm. TEM observations revealed the generation of spherical TiO2 nanoparticles (4-5 nm) assembled to form stable spongy scaffold having porous network structure with pore size 5-6 nm. Also, presence of a pronounced hysteresis loop in BET isotherm is indicative of a 3D-intersection network of the pores of size 4-5 nm. Further heat-treatment to the aged precursor at 400 degrees C/2 h in air modify pore network structure due to sintering of TiO2 particles as is observed in TEM studies and lowering thereby the surface area to 125 m(2) g(-1) (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Microstructure, porous materials, sol-gel processing, titania}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2005.02.014}, author = {Deshpande, S. B. and Potdar, H. S. and Khollam, Y. B. and Patil, K. R. and Pasricha, R. and Jacob, Nalini E.} } @article { ISI:000242511300022, title = {Adsorption of methanol on mesoporous SBA-15}, journal = {Materials Letter}, volume = {61}, number = {1}, year = {2007}, month = {JAN}, pages = {88-92}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The adsorption of methanol onmesoporous SBA-15 has been studiedbyrising Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoclectrom spectroscopy (XPS) and tbennogravimettic analysis (TGA). The BET surface area analysis shows decreases of the surface area from 387 to 383 m(2)/g, pore volume from 0.88 to 0.81 cm(3)/g and pore diameter from 9.07 to 8.4 mm after methanol adsorption. The appearance of strong IR bands at 2862 and 2964cm(-1) due to methyl (-CH3) symmetric and asymmetric stretching demonstrate the presence of methanol and evidence of successful methanol adsorption. XPS results show increase of carbon and oxygen content on the surface of SBA-15. Thermogravirriettic analysis shows that the methanol adsorbed on SBA-15 is stable up to a temperature of 265 degrees C and that the methanol adlayers decompose between 265 and 588 degrees C. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Adsorption, Electron microscopy, Methanol, SBA-15, Surfaces, thermal stability}, issn = {0167-577X}, doi = {10.1016/j.matlet.2006.04.012}, author = {Mirji, S. A. and Halligudi, Shivaraj B. and Mathew, Nevin T. and Jacob, Nalini E. and Patil, K. R. and Gaikwad, A. B.} }