Papers by Raksh Vir Jasra
Industrial & Engineering Chemistry Research, 2008
Industrial & Engineering Chemistry Research, 2006
This study investigated the role of the band gap, surface area, and phase composition on the phot... more This study investigated the role of the band gap, surface area, and phase composition on the photocatalytic activity of nanocrystalline TiO 2 . Nanocrystalline TiO 2 (8-29 nm) was synthesized by hydrolysis of titanium tetraisopropoxide. The crystalline structure, band gap, and morphology of the nanocrystalline TiO 2 were determined by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and N 2 adsorption (BET) at 77 K, respectively. It is observed that the band gap of the nanocrystalline TiO 2 decreases from 3.29 to 3.01 eV with increasing calcination temperature. The crystallite size of the TiO 2 samples prepared also shows an increase with increasing calcination temperature. The photocatalytic degradation of an aqueous solution of nitrobenzene (50 ppm) was studied using nanocrystalline TiO 2 samples with varying band-gap values, as well as a P-25 Degussa TiO 2 sample for comparison. The initial rate of degradation of nitrobenzene was calculated in each case to evaluate the photocatalytic activity of the catalysts. The enhanced photocatalytic degradation of nitrobenzene was observed by purging air through the solution during photocatalysis.
Microporous Materials, 1997
Sorption isotherms for n-pentane, 2-methylbutane and cyclopentane in the aluminophosphate molecul... more Sorption isotherms for n-pentane, 2-methylbutane and cyclopentane in the aluminophosphate molecular sieve AlPO 4 -5 are reported at 303, 313, 323 and 333 K. The sorption data were fitted into Langmuir, Sips and Dubinin-Radushkevich isotherms. The heats of sorption at zero coverage determined from the data in the Henry region are in the order 2-methylbutane>cyclopentane>n-pentane. Free energy and entropy changes and heats of sorption for these sorbates at various sorption coverages were also determined from the sorption data. The heat of sorption for n-pentane varies only marginally with sorption coverage. However, the heats of sorption for 2-methylbutane and cyclopentane increase significantly with the coverage indicating an increase in sorbate-sorbate interactions. The dependence of thermodynamic properties like the free energy of sorption (DG) and the entropy change (DS) for 2-methylbutane and cyclopentane on coverage show a sharp decrease and increase at sorption coverages 0.1-0.2 mmol g−1 suggesting the rearrangement of molecular packing in the sorbed phase. These observations have been explained in terms of molecular interactions between the AlPO 4 -5 channels and sorbate molecules. © 1997 Elsevier Science B.V.
Coordination Chemistry Reviews, 2008
Chiral cyanohydrins are versatile building blocks for pharmaceuticals, agrochemicals and specialt... more Chiral cyanohydrins are versatile building blocks for pharmaceuticals, agrochemicals and specialty materials. A number of efficient and successful synthetic methods have been developed however, the chiral catalytic method is one of the most attractive strategies ...
Journal of Chemical Sciences, 2014
ABSTRACT Elastomer business plays a significant role in the transportation industry. In fact, ela... more ABSTRACT Elastomer business plays a significant role in the transportation industry. In fact, elastomers make the world move. Due to limited availability of natural rubber, synthetic elastomers bridge the gap between demand and supply in today’s growing tyre and automobile industry. With more than ∼ 10000 KTA total world productions, the impact of synthetic elastomer business cannot be overlooked. The need of synthetic elastomers for tyre and automobile industries is stringently specific. Catalysis plays an inevitable role in achieving the growing demand of specific synthetic elastomers. The present study will describe how catalysis plays a significant role in the sustainable development of elastomers with special reference to polybutadiene rubber. ᅟ Development fromTitanium- to latest Neodymium-based Z–N commercial catalyst is a strong evidence of promising future of catalysis in synthetic elastomer business. The research is mainly focused on development of novel single-site metallocene and allyl-derivatives based catalysts to obtain high molecular weight polymers with precise control upon chemo- and stereo-selectivity.
a b s t r a c t Ni, Rh and Pd incorporated mesoporous MCM-41, MCM-48, HMS and SBA-15 samples were... more a b s t r a c t Ni, Rh and Pd incorporated mesoporous MCM-41, MCM-48, HMS and SBA-15 samples were synthesized and were characterized using XRD, ICP/EDX and N 2 adsorption-desorption at 77.4 K. The hydrogen adsorption studies in the synthesized materials were performed at 77.4 K (up to 112 kPa) and 303 K (up to 4000 kPa). The hydrogen adsorption isotherms of pristine and transition metals incorporated mesoporous materials at 77.4 K were completely reversible reflecting physisorption of hydrogen in these materials. The hydrogen adsorption isotherms at 303 K were not reversible showing the chemisorption of hydrogen in these materials at 303 K. Hydrogen sorption studies showed that transition metal modification improved the hydrogen storage capacity of mesoporous materials at 303 K. The desorption of the adsorbed hydrogen by heating up to 500 K from the mesoporous materials were also carried out for studying the recovery of adsorbed hydrogen from transition metal incorporated mesoporous materials. (R.V. Jasra).
A ruthenium-based complex, ethylenediaminetetraacetato ruthenate [Ru-EDTA(H 2 O)] À 1 was found t... more A ruthenium-based complex, ethylenediaminetetraacetato ruthenate [Ru-EDTA(H 2 O)] À 1 was found to be an efficient homogeneous catalyst to activate carbon monoxide as well as water molecule in hydration of CO. It was investigated at moderate pressures (5-20 atm) and at 10-40 8C for direct conversion of CO to formic acid (FA). In typical catalytic experiments conducted in a pressure reactor of 300 ml capacity, 75 Â 10 À3 M of FA was found to be formed at 10 atm CO pressure and 40 8C. The kinetics of the (i) complexation of CO with 1 and (ii) hydration of CO to formic acid reactions were investigated in detail by studying the rate of formation of intermediate Ru-EDTA-CO complex 2 and the rate of formation of FA, respectively as a function of the concentration of the catalyst 1, CO pressure, reaction temperature, ionic strength and pH. The rate of formation of FAwas found to be first order with respect to the concentration of 1 and CO pressure, independent of pH and ionic strength, and dependent on temperature, in agreement with the Arrhenius equation. Similar kinetic profile and temperature dependence were observed for formation of complex 2 also. Activation parameters evaluated from temperature dependence were found to be favorable for the formation of 2 and the CO hydration product FA. Based on kinetic and experimental results, a mechanism for the hydration of CO to formic acid is suggested. #
Specific activity of a-amylase immobilized in ordered mesoporous silicas (26-335 Å pore diameter)... more Specific activity of a-amylase immobilized in ordered mesoporous silicas (26-335 Å pore diameter) for hydrolysis of starch has been studied. In mesoporous silica like MCM-41 and SBA-15, enzyme is immobilized only on the external surface and thus the observed specific activity is low. For meso-cellular foams (MCF), MCF-153 and MCF-335 having higher pore diameter, enzyme seems to be immobilized inside the pores and high specific activity increase was observed. In fact, MCF-335 shows specific activity equal to 80% of the specific activity of free enzyme. It was further observed that, thermal and pH stability of the immobilized enzyme is higher compared to free a-amylase. Immobilization of a-amylase in these silicas was carried out using three-step process through alkylamine and glutaraldehyde. Alkylamine was covalently bonded to silanol groups present on the surface of mesoporous silica followed by reaction of aldehyde with alkylamine. Enzyme molecules were immobilized on thus modified silica through reaction of free -CHO with -NH 2 of enzyme.
SWNT Hydrogen sorption a b s t r a c t MetaleOrganic Frameworks (MOFs) have emerged as potential ... more SWNT Hydrogen sorption a b s t r a c t MetaleOrganic Frameworks (MOFs) have emerged as potential hydrogen storage media due to their high surface area, pore volume and adjustable pore sizes. The large void space generated by cages in MOFs is not completely utilized for hydrogen storage application owing to weak interactions between the walls of MOFs and H 2 molecules. These unutilized volumes in MOFs can be effectively utilized by incorporation of other microporous materials such as single walled carbon nanotubes into the pores of MOFs which could effectively tune the pore size and pore volume of the material towards hydrogen sorption. Single walled carbon nanotubes (SWNT) incorporated MIL-101 composite MOF material (SWNT@MIL-101) was synthesized by adding purified single walled carbon nanotube (SWNT) in situ during the synthesis of MIL-101.
a b s t r a c t Ni, Rh and Pd incorporated mesoporous MCM-41, MCM-48, HMS and SBA-15 samples were... more a b s t r a c t Ni, Rh and Pd incorporated mesoporous MCM-41, MCM-48, HMS and SBA-15 samples were synthesized and were characterized using XRD, ICP/EDX and N 2 adsorption-desorption at 77.4 K. The hydrogen adsorption studies in the synthesized materials were performed at 77.4 K (up to 112 kPa) and 303 K (up to 4000 kPa). The hydrogen adsorption isotherms of pristine and transition metals incorporated mesoporous materials at 77.4 K were completely reversible reflecting physisorption of hydrogen in these materials. The hydrogen adsorption isotherms at 303 K were not reversible showing the chemisorption of hydrogen in these materials at 303 K. Hydrogen sorption studies showed that transition metal modification improved the hydrogen storage capacity of mesoporous materials at 303 K. The desorption of the adsorbed hydrogen by heating up to 500 K from the mesoporous materials were also carried out for studying the recovery of adsorbed hydrogen from transition metal incorporated mesoporous materials. (R.V. Jasra).
Adsorption Science and Technology - Proceedings of the Third Pacific Basin Conference, 2003
Tetrahedron, 2000
AbstractÐA series of a-diazo carbonyl compounds having cyclopentanone, cyclohexanone and substitu... more AbstractÐA series of a-diazo carbonyl compounds having cyclopentanone, cyclohexanone and substituted cyclohexanone units with different tether lengths have been synthesized using diazomethane solution or methanesulphonyl azide. The above synthesized a-diazo carbonyl compounds with rhodium(II) acetate dimer furnish cyclic ®ve-or six-ring carbonyl ylide dipoles, which undergo facile 1,3-dipolar cycloaddition with different dipolarophiles to furnish the substituted and functionalized oxatricyclic systems having various ring sizes. Two X-ray crystallographic analyses of compounds 8b and 15a are reported to ®rmly establish the stereochemistry of the cycloadducts. q
ChemInform, 2002
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Journal of the Chemical Society, Chemical Communications, 1994
A rapid method is reported for the hydrothermal synthesis of AIP04-5 by which the 100% pure cryst... more A rapid method is reported for the hydrothermal synthesis of AIP04-5 by which the 100% pure crystalline phase is obtained in 90 min at 150°C using aluminium triisopropoxide, phosphoric acid and tripropylamine in the system free of Fions.
Studies in Surface Science and Catalysis, 2008
... Microwave synthesized mesoporous Tin MFI as efficient catalyst for Baeyer-Villiger Oxidation ... more ... Microwave synthesized mesoporous Tin MFI as efficient catalyst for Baeyer-Villiger Oxidation of cyclic ketones Krishna Mohan Jinka,a,b Seung-Cheol Lee,a Sang-Eon Park,a,* and Raksh Vir Jasra b,* a Laboratory of Nano-Green ... (1994) 1933 [12] A. Corma, LT Nemeth, M. Renz ...
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Papers by Raksh Vir Jasra