@article { ISI:000309370500003, title = {Carbon dioxide capture using amine functionalized silica gel}, journal = {Indian Journal of Chemistry Section A-Inorganic Bio-Inorganic Physical Theoretical \& Analytical Chemistry}, volume = {51}, number = {9-10, SI}, year = {2012}, month = {SEP}, pages = {1214-1222}, publisher = {NATL INST SCIENCE COMMUNICATION-NISCAIR}, address = {DR K S KRISHNAN MARG, PUSA CAMPUS, NEW DELHI 110 012, INDIA}, abstract = {

Commercially available silica gel is chemically modified for carbon dioxide capture. Calcinated silica gel of certain particle size functionalized with amine using two different methods, wet impregnation and grafting via silane chemistry has been employed as a porous media. The prepared material is characterized by Fourier transform infrared, scanning electron microscopy, energy dispersive analysis of X-rays, thermogravimetry and N-2 physisorption techniques. Gas uptake measurements have been carried out to ascertain the CO2 capture capacity of the amine functionalized material. The experiments have been carried out at moderate pressure and temperature range to ascertain its potential for easy scale up.

}, keywords = {Amine functionalized silica gel, Carbon dioxide capture, grafting, Poly(ethyleneimine), Silane chemistry, Wet impregnation}, issn = {0376-4710}, author = {Sakpal, Tushar and Kumar, Asheesh and Kamble, Sanjay and Kumar, Rajnish} } @article { ISI:000355645000021, title = {Carbon dioxide sequestration: influence of porous media on hydrate formation kinetics}, journal = {ACS Sustainable Chemistry \& Engineering}, volume = {3}, number = {6}, year = {2015}, month = {JUN}, pages = {1205-1214}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

In the present study, CO, sequestration by hydrate formation in porous sediments has been discussed. Two siliceous materials with high porosities, pumice and fire hardened red clay (FHRC), have been used as packing materials in a fixed bed setup to study hydrate formation kinetics. The results obtained using the aforementioned materials were compared with those obtained using silica sand and quartz. Carbon dioxide hydrate formation kinetics was studied at 3.0 MPa pressure and 274 K temperature. Two different types of experiments were conducted: (a) using a constant volume of water and (b) maintaining a constant bed height. These experiments were conducted using the different porous media individually as packing materials. It was observed that pumice as the porous medium showed better hydrate formation kinetics resulting in 46 mol \% water to hydrate conversion in 5 h. Moreover, kinetics was enhanced with decrease in the bed height of pumice; this suggests that at field scale adaptation of CO, sequestration in geological formations, mass transfer limitations would be significant. The effects of particle size on hydrate formation kinetics were also investigated. It was observed that hydrate formation kinetics was enhanced with decrease in the particle size fraction.

}, keywords = {Bed height, Gas hydrate, gas uptake, Geological sequestration, Particle size}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.5b00171}, author = {Bhattacharjee, Gaurav and Kumar, Asheesh and Sakpal, Tushar and Kumar, Rajnish} } @article { ISI:000377466600023, title = {Crystallization kinetics for carbon dioxide gas hydrate in fixed bed and stirred tank reactor}, journal = {Korean Journal of Chemical Engineering}, volume = {33}, number = {6}, year = {2016}, month = {JUN}, pages = {1922-1930}, publisher = {KOREAN INSTITUTE CHEMICAL ENGINEERS}, address = {F.5, 119, ANAM-RO, SEONGBUK-GU, SEOUL 136-075, SOUTH KOREA}, abstract = {

The phase change from germ nuclei to growth nuclei and subsequent volume transformation in a crystallization process was modeled by Avrami equations. The phase change during the hydrate formation was fitted with the classical Avrami model by utilizing gas uptake data. The idea is to understand the difference in growth behavior of hydrate crystals when in small pores compared to a stirred tank reactor which does not pose any physical restrictions to hydrate growth. The parameters n and k of the Avrami equation were determined explicitly for CO2 hydrate formation.

}, keywords = {Avrami Equation, CO2 Capture \& Sequestration, Fixed Bed, Gas hydrates, kinetics}, issn = {0256-1115}, doi = {10.1007/s11814-016-0040-7}, author = {Kumar, Asheesh and Khatri, Dishant and Lee, Ju Dong and Kumar, Rajnish} } @article {45521, title = {Comparison of different water models for melting point calculation of methane hydrate using molecular dynamics simulations}, journal = {Chemical Physics}, volume = {516}, year = {2019}, month = {JAN }, pages = {6-14}, type = {Article}, abstract = {

Molecular dynamics simulation is a powerful tool to understand the gas hydrate nucleation, growth, and dissociation at molecular level. Prerequisite of super-cooling during gas hydrate formation and a certain degree of super-healing during melting shows significant hysteresis in the transition between solid and liquid state due to large nucleation barrier. Different water models quantitatively differ in their prediction of thermodynamic and kinetic properties of bulk water, including phase behaviour. The present work carries out a systematic investigation of the effect of the chosen water model on the phase behaviour, in particular, the decomposition of methane hydrate. Void-induced melting has been used to predict the melting point of methane hydrate using TIP4P/Ice, TIP4P/2005, TIP4P, and SPC/E water models. This method avoids the need for a predetermined interface for melting point calculations and thus may have its importance in identifying dissociation kinetics of bulk hydrate.

}, keywords = {decomposition, Gas hydrates, Void-induced melting, Water models}, issn = {0301-0104}, doi = {10.1016/j.chemphys.2018.08.036}, author = {Choudhary, Nilesh and Chakrabarty, Suman and Roy, Sudip and Kumar, Rajnish} }