Anup Talukdar | Gauhati University (original) (raw)

Papers by Anup Talukdar

Asian Journal of Chemistry, 2021

Four samples of MFI zeolites with silica to alumina ratio of 100 and using different silica to ca... more Four samples of MFI zeolites with silica to alumina ratio of 100 and using different silica to carbon mass ratios (1:1, 1:4, 1:8 and 1:12) were synthesized by using carbon black particles. Silica-alumina molar ratio imposes the framework structure to the synthesized zeolites. In general with an increase in the silica-alumina molar gel ratio, the thermal stability, acid resistance and hydrophobicity of the product increases and ion-exchange capacity decreases. A higher molar ratio (as high as 100) of silica to alumina is considered. ZSM-5 zeolites being mainly microporous, their use as catalyst is restricted only to small molecules. So, by introducing mesopores in zeolite framework, we basically tried to overcome the limited use of ZSM-5 in reactions involving large molecules. Pore structure of ZSM-5 can be modified by using carbon black particles during synthesis. Such type of synthesis can be used to introduce the mesopore and to decrease the crystal size of ZSM-5 zeolite. Differen...

New Journal of Chemistry, 2021

Hydrothermal synthesis of ZSM-5/MCM-41 composite has been carried out from pre-synthesized ZSM-5 ... more Hydrothermal synthesis of ZSM-5/MCM-41 composite has been carried out from pre-synthesized ZSM-5 zeolite as silica source and CTAB as template. The ZSM-5/MCM-41 composite materials were further loaded with varying wt%...

Advances in Nanoparticles, 2021

Fluoride above 1.5 mg·L −1 is injurious to health. Removal of fluoride from water using mesoporou... more Fluoride above 1.5 mg·L −1 is injurious to health. Removal of fluoride from water using mesoporous MCM-41 as a strong adsorbent material has been attempted. Characterization using transmission electron microscopic study of calcined MCM-41 showed the regular hexagonal array of mesoporous channels with an average size of 20 nm and the surface area (BET study) of 1306.96 m 2 ·g −1. The average pore size of the particles was found to be 14.21 nm. A study on the effect of contact time on the removal of fluoride revealed that more than 85% uptake of fluoride onto MCM-41 was achieved at a contact time of 120 min. From the Langmuir adsorption study, the maximum sorption capacity of fluoride was found to be 63.05 mg/g at 301 K. From the thermodynamic study, the +ΔH˚ value of 2.29 kJ·mol −1 indicated the endothermic nature of the removal process. Application of Response Surface Model suggested that 77.88% of fluoride removal can be achieved at fluoride concentration of 10 mg·L −1 , pH (6.3), and contact time of 120 min.

ChemistrySelect, 2017

High-surface area Nb 2 O 5 nanoparticles were synthesised by a novel supercritical-CO 2-assisted ... more High-surface area Nb 2 O 5 nanoparticles were synthesised by a novel supercritical-CO 2-assisted method (Nb 2 O 5-scCO 2) and were applied for the first time as a heterogeneous catalyst in the oxidative coupling of aniline to azoxybenzene using the environmentally friendly H 2 O 2 as the oxidant. The application of scCO 2 in the synthesis of Nb 2 O 5-scCO 2 catalyst resulted in a significantly enhanced catalytic activity compared to a reference catalyst prepared without scCO 2 (Nb 2 O 5-Ref) or to commercial Nb 2 O 5. Importantly, the Nb 2 O 5-scCO 2 catalyst achieved an aniline conversion of 86% (stoichiometric maximum of 93% with the employed aniline-to-H 2 O 2 ratio of 1 : 1.4) with an azoxybenzene selectivity of 92% and with 95% efficiency in H 2 O 2 utilisation in 45 min without requiring external heating (the reaction is exothermic) and with an extremely low catalyst loading (weight ratio between the catalyst and substrate, R c/s = 0.005). This performance largely surpasses that of any other heterogeneous catalyst previously reported for this reaction. Additionally, the Nb 2 O 5 catalyst displayed high activity also for substituted anilines (e.g. methyl or ethyl-anilines and para-anisidine) and was reused in consecutive runs without any loss of activity. Characterisation by means of N 2-physisorption, XRD, FTIR and TEM allowed the correlation of the remarkable catalytic performance of Nb 2 O 5-scCO 2 to its higher surface area and discrete nanoparticle morphology compared to the aggregated larger particles constituting the material prepared without scCO 2. A catalytic test in the presence of a radical scavenger proved that the reaction follows a radical pathway. † Electronic supplementary information (ESI) available: Image of the highthroughput scCO 2 reactor. Kinetic study of 20 mmol aniline conversion over the Nb 2 O 5-scCO 2 catalyst. Pictures of 50 mmol aniline conversion over Nb 2 O 5-scCO 2 and Nb 2 O 5-Ref catalysts as a function of time. XRD pattern of Nb 2 O 5-800°C. TEM pictures of Nb 2 O 5-scCO 2. SEM images of Nb 2 O 5-scCO 2 and Nb 2 O 5-Ref catalysts. Pictures of conversion of aniline with different concentrations of H 2 O 2 after 25 min. Plots of aniline conversion and products yields in different solvents. Reusability test of the Nb 2 O 5-scCO 2 catalyst. Comparison with the previously reported heterogeneous catalysts. List of chemicals and their purity used in this work. Reaction pathway from the oxidative coupling of aniline with H 2 O 2 to azoxybenzene over the Nb 2 O 5-scCO 2 catalyst. See

Russian Journal of Physical Chemistry A, 2018

The present work deals with the adsorption of Cu2+ and Pb2+ on zeolites (ZSM-5, mordenite) and me... more The present work deals with the adsorption of Cu2+ and Pb2+ on zeolites (ZSM-5, mordenite) and mesoporous materials (MCM-48, MCM-41). The characterization of the synthesized samples was performed by means of XRD, SEM, and thermogravimetric analysis. The batch method was employed to study the influence of adsorbent nature, contact time, initial metal ion concentration, and adsorbent load. The adsorption on MCM-48 follows a pseudo-second-order kinetic model. This material was found to be more effective for the removal of lead in a batch process as compared to the other adsorbents and the removal efficiency of the materials for Pb(II) followed the order MCM-48 > mordenite > ZSM-5 > MCM-41 and that for Cu(II) followed the order ZSM-5 > mordenite > MCM-41 > MCM-48.

Materials Research Bulletin, 2018

Abstract A series of Ti containing MCM-41 materials were synthesized with different Si/Ti molar r... more Abstract A series of Ti containing MCM-41 materials were synthesized with different Si/Ti molar ratios and tested for cyclohexene epoxidation reaction. TiMCM-41 with Si/Ti ratio 40 which gave maximum conversion and selectivity to epoxide was methylated with methyltriethoxysilane (MTES) in this reaction. Accordingly, four different methyl loading (5, 10, 15 and 20 mol % of MTES w.r.t. TEOS) TiMCM-41(Si/Ti 40) samples were prepared. The materials were characterized by different physical techniques such as PXRD, FT-IR spectroscopy, UV–vis DRS spectroscopy, N2 adsorption-desorption isotherm, SEM-EDX, TEM, TGA and ICP-OES. The catalysts were then tested for cyclohexene epoxidation reaction in the presence of H2O2 avoiding TBHP. The conversion and selectivity for cyclohexene obtained with 10MeTiM-1 (Si/Ti 40) were found to be the best not only among the catalysts investigated in the present work, but also among all the catalysts studied so far for the reaction.

Journal of Porous Materials, 2019

Journal of Environmental Chemical Engineering, 2017

Abstract Adsorptive removal of Cr(VI) by N -3-trimethoxysilylpropylethylenediamine (AEAPTMS) func... more Abstract Adsorptive removal of Cr(VI) by N -3-trimethoxysilylpropylethylenediamine (AEAPTMS) functionalised MCM-48 prepared via grafting method was investigated with respect to contact time, adsorbent dose, initial metal ion concentration, pH, amine loading and temperature. The synthesized samples were characterized by X-ray diffraction (XRD), fourier transform infrared (FTIR) spectrocopy, scanning electron microscopy (SEM), N 2 adsorption-desorption isotherm and thermogravimetric analysis (TGA). 1.5 mmol AEAPTMS functionalised MCM-48 sample showed highest adsorption among the modified samples under similar conditions. Adsorption kinetics was successfully fitted by pseudo second-order kinetic model. The experimental data fitted well to the Langmuir adsorption isotherm model with a calculated maximum adsorption capacity of 166.67 mg/g. The overall adsorption was a spontaneous and endothermic process as signified by the thermodynamic parameters. Another aspect of the work was the high catalytic efficiency of chromium containing spent adsorbent obtained by adsorption of Cr(VI) from the aqueous solution. The catalytic activity of the obtained catalyst was found to depend on the amount of adsorbed chromium. The spent adsorbents behaved as efficient catalysts for oxidation of cyclohexene (81.0% conversion) and ethylbenzene (94.6% conversion) with 96.7% and 100% selectivity towards desired product when 70% tert-Butyl hydroperoxide (TBHP) was used as oxidant.

Current Science, 2009

Pot culture experiments were conducted to investigate the effect of lime sludge waste on the grow... more Pot culture experiments were conducted to investigate the effect of lime sludge waste on the growth and production of some agricultural crops like mustard (cv. CVM 27), pea (cv. Rashna 30) and rice (cv. Aijong) as well as the physicochemical properties of the ...

2014 Ieee 79th Vehicular Technology Conference, May 1, 2014

Applied Catalysis a General, Mar 1, 1993

The vapour-phase hydrogenation of phenol over platinum and palladium supported on alumina and xeo... more The vapour-phase hydrogenation of phenol over platinum and palladium supported on alumina and xeolite LTL was studied in a vertical fixed-bed high-pressure reactor. The major products of the hydrogenation reaction were cyclohexanone and cyclohexanol with cyclohexane, cyclohexene and benzene as the minor products. The selectivity for the major products was upto 99%, the conversion being influenced by temperature, feed rate and the partial pressure of hydrogen. Platinum catalysts were found to be better for the production of cyclohexanol while palladium catalysts favoured cyclohexanone production. The platinum catalysts also showed twice as much overall conversion as the palladium catalysts.

Journal of Porous Materials, 2016

Arabian Journal of Chemistry, 2016

Catalysis Science & Technology, 2012