@article { ISI:000260774300012, title = {Sol-gel synthesis of MoO(3)/SiO(2) composite for catalytic application in condensation of anisole with paraformaldehyde}, journal = {Catalysis Letters}, volume = {126}, number = {3-4}, year = {2008}, month = {DEC}, pages = {286-292}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

MoO(3)/SiO(2) composite with varying amounts of MoO(3) loading (1-20 wt.\%) were prepared by sol-gel method and calcined at 500 C. These catalysts were employed for the liquid phase condensation of anisole with paraformaldehyde. All the catalysts were characterized by N(2) sorption, XRD, and NH(3)-TPD. The activities of synthesized MoO(3)/SiO(2) catalysts were compared with p-toluene sulfonic acid (p-TSA), the most frequently used catalyst for the condensation reactions, and with a supported metal oxide (WO (x) /ZrO(2)). Under the similar reaction conditions, synthesized 10 wt.\% MoO(3)/SiO(2) catalyst calcined at 500 C was found to be the most active in the condensation of anisole with paraformaldehyde.

}, keywords = {4, 4{\textquoteright}-Dimethoxydiphenylmethane, Condensation of anisole, MoO(3)/SiO(2) composites, Paraformaldehyde, Sol-gel synthesis}, issn = {1011-372X}, doi = {10.1007/s10562-008-9611-5}, author = {Amrute, Amol P. and Bordoloi, Ankur and Lucas, Nishita and Palraj, K. and Halligudi, Shivaraj B.} } @article { ISI:000271542900148, title = {On the structural, magnetic and electrical properties of sol-gel derived nanosized cobalt ferrite}, journal = {Journal of Alloys and Compounds}, volume = {485}, number = {1-2}, year = {2009}, month = {OCT}, pages = {711-717}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

Nanoparticles of cobalt ferrite were synthesized by sol gel method. These particles were structurally characterized by using X-Ray Diffraction and Transmission Electron Microscopy, High Resolution Transmission Electron Microscopy, Energy Dispersive Spectrum and Inductively Coupled Plasma Analysis and the results confirmed the formation of spherically shaped nanoparticles of cobalt ferrite having a size lying in the range of 13-14 nm. The as prepared sample was sintered at 800 degrees C and the structural, magnetic and dielectric properties were measured. The dielectric properties were studied and analyzed as a function of temperature and frequency. The ac and dc conductivity studies were carried out to delve into the conduction mechanism. The existing models based on quantum mechanical tunneling were effectively employed to explain the frequency dependent conductivity. (C) 2009 Elsevier B.V. All rights reserved.

}, keywords = {Electronic Transport, Magnetic measurements, Magnetically ordered materials, Nanostructures, Scanning and transmission electron microscopy, Sol-gel synthesis, X-ray diffraction}, issn = {0925-8388}, doi = {10.1016/j.jallcom.2009.06.033}, author = {Gopalan, E. Veena and Joy, Pattayil Alias and Al-Omari, I. A. and Kumar, D. Sakthi and Yoshida, Yasuhiko and Anantharaman, Maliemadom R.} } @article { ISI:000278305600001, title = {Magnetic, dielectric and complex impedance spectroscopic studies of nanocrystalline Cr substituted Li-ferrite}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {322}, number = {18}, year = {2010}, month = {SEP}, pages = {2629-2633}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Nanocrystalline Li0.5Fe2.5-xCrxO4 (2.5 \<= x \>= 0) ferrites were prepared by a sol-gel autocombustion route. X-ray diffraction was employed to confirm the cubic spinel phase formation of the ferrites. The lattice parameter decreases with increase in Cr content. The saturation magnetization, coercivity and remanance were studied as a function of Cr content. The dielectric constant and dielectric loss were measured as a function of frequency in the frequency range 20 Hz-1 MHz. Frequency dependence of dielectric constant shows dielectric dispersion due to the Maxwell-Wagner type of interfacial polarization. In order to understand the conduction mechanism, complex impedance measurements were carried out. The substitution of chromium plays an important role in changing the dielectric and magnetic properties of lithium ferrites. (C) 2010 Published by Elsevier B.V.

}, keywords = {Complex impedance, dielectric response, Ferrites, Magnetic hysteresis, Sol-gel synthesis, X-ray diffraction}, issn = {0304-8853}, doi = {10.1016/j.jmmm.2010.03.005}, author = {Hankare, P. P. and Patil, R. P. and Sankpal, U. B. and Garadkar, K. M. and Sasikala, R. and Tripathi, A. K. and Mulla, Imtiaz S.} } @article { ISI:000319027400029, title = {Functional and disordered meso-macroporous gamma-Al2-xMxO3 +/- y (M = Cu and/or Ce)}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {13}, number = {4, SI}, year = {2013}, month = {APR}, pages = {2682-2688}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {Disordered meso-macro porous Cu-Ce-Al2O3 nanocomposite (gamma-Al2-xMxO3 +/- y, M = Cu and or Ce) with different compositions has been synthesized. In situ templated sol-gel method has been adopted with simple EDTA ethylenediamine tetra aceticacid and ethylenediamine molecules to prepare gamma-Al2-xMxO3 +/- y, (M = Cu and or Ce). Above meso-macro porous materials were characterized by structural, spectroscopy, microscopy and textural techniques. Detailed characterization indicates that Cu2+ ions are introduced into the ceria and alumina lattice positions. Nano composite nature of the gamma-Al2-xMxO3 +/- y has been confirmed by detailed microscopy investigations. Catalytic activity of the above nanocomposite materials have been screened for environmentally important CO oxidation reaction. 30\% Ce-60\% Al and 10\% Cu containing material shows the best activity among other meso-nnacroporous material with (50\%) 100\% CO oxidation at (107 degrees C) 145 degrees C.}, keywords = {Alumina, CO oxidation, heterogeneous catalysis, Meso-Macroporous Material, Nanocomposite, Sol-gel synthesis}, issn = {1533-4880}, doi = {10.1166/jnn.2013.7384}, author = {Gnanakumar, Edwin S. and John, Jino C. and Raja, Thirumalaiswamy and Gopinath, Chinnakonda S.} } @article { ISI:000365050700016, title = {Sol-gel synthesised WO3 nanoparticles supported on mesoporous silica for liquid phase nitration of aromatics}, journal = {Applied Catalysis B-Environmental}, volume = {182}, year = {2016}, month = {MAR}, pages = {142-152}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A series of WO3/SiO2 catalysts have been prepared by sol-gel method using ammonium metatungstate and ethyl silicate-40 (ES-40) as WO3 and SiO2 precursors respectively. The sol-gel method has led to the formation of WO3 nano-particles of 2-5 nm well dispersed on mesoporous silica along with some WO3{\textquoteright} agglomerates. Formation of monoclinic WO3 was seen on the catalysts above 5 wt\% WO3 loading by XRD analysis. Silica has shown very high surface area of 606 m(2)/g which decreased gradually upto 368 m(2)/g with 20 wt\% WO3 loading. 20 wt\% WO3/SiO2 catalyst has shown maximum acidity (0.56 mmol NH3/g) with presence of both Lewis and Bronsted acidity. UV-vis DRS analysis showed formation of polytungstate species along with WO3 on silica surface. The prepared catalysts were used for liquid phase nitration of aromatics using 70\% nitric acid as nitrating agent without using any sulfuric acid. Very high conversion (99\%) was obtained for p-cresol nitration with very high selectivity (99\%) for 2-nitro p-cresol. The water formed during the reaction was removed azeotropically using ethylene dichloride as solvent. In case of o-xylene 74\% conversion was obtained with 54\% selectivity for 4-nitro o-xylene. The effect of different WO3 precursors on nitration efficiency was studied using sodium tungstate and tungstic acid as precursors. However,ammonium metatungstate showed the highest acidity. Sodium tungstate showed formation of dimer of sodium tungstate which did not show any acidity and hence no activity for nitration. The mechanism for nitration using WO3/SiO2 has been proposed based on polarisation of water on tungsten centre generating Bronsted acidity which can further generate nitronium ion giving subsequently nitration of the aromatic ring. (C) 2015 Elsevier B.V. All rights reserved.

}, keywords = {Aromatic nitration, heterogeneous catalysis, Regioselective, Sol-gel synthesis, Water polarization}, issn = {0926-3373}, doi = {10.1016/j.apcatb.2015.09.020}, author = {Kulal, A. B. and Dongare, Mohan K. and Shubhangi B. Umbarkar} } @article {46160, title = {Hydrophobic WO3/SiO2 catalyst for the nitration of aromatics in liquid phase}, journal = {Applied Catalysis A-General}, volume = {574}, year = {2019}, month = {MAR}, pages = {105-113}, type = {Article}, abstract = {

WO3/SiO2 solid acid catalyst synthesized using sol gel method has shown promising activity (up to 65\% conversion) for aromatic nitration in liquid phase using commercial nitric acid (70\%) as nitrating agent without using any sulfuric acid. The water formed during the reaction as well as water from dilute nitric acid (70\%) was removed azeotropically, however due to the hydrophilic nature of the catalyst, some water gets strongly adsorbed on catalyst surface forming a barrier layer between catalyst and organics. This prevents effective adsorption of substrate on catalyst surface for its subsequent reaction. To improve the activity further, the hydrophilic/hydrophobic nature of the catalyst was altered by post modification by grafting with commercial short chain organosilane (Dynasylan 9896). The modified 20\% WO3/SiO2 catalyst when used for o-xylene nitration in liquid phase, showed significant increase in the conversion from 65\% to 80\% under identical reaction conditions. Catalyst characterization revealed decrease in the surface area of 20\% WO3/SiO2 from 356 m(2)/g to 302 m(2)/g after grafting with Dynasylan 9896. The fine dispersion of WO3 particles (2-5 run) on silica support was not affected due to modification. NMR and FTIR study revealed the decrease in surface hydroxyl groups imparting hydrophobicity to the catalyst. Interestingly the total acidic sites of the catalyst remained almost unaltered (0.54 mmol NH3/g) even after modification. Even though, the acidity and other characteristics of the catalyst did not change appreciably, there was a considerable increase in the o-xylene conversion which can be ascribed to the hydrophobic nature of the catalyst.

}, keywords = {Aromatic nitration, grafting, heterogeneous catalysis, Hydrophobic, Sol-gel synthesis}, issn = {0926-860X}, doi = {10.1016/j.apcata.2019.02.002}, author = {Kulal, A. B. and Kasabe, M. M. and Jadhav, P. V. and Dongare, M. K. and Umbarkar, S. B.} }