02290nas a2200253 4500008004100000022001400041245014900055210006900204260010600273300001200379490000700391520130600398653002701704653002201731653002201753653001701775653002701792653001401819100002301833700001801856700001901874700001901893856012401912 2014 eng d a0360-544200aEnhanced kinetics for the clathrate process in a fixed bed reactor in the presence of liquid promoters for pre-combustion carbon dioxide capture0 aEnhanced kinetics for the clathrate process in a fixed bed react aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcJUN a664-6730 v703 a

In this work, we present enhanced kinetics of hydrate formation for the clathrate process in the presence of two liquid promoters namely THF (tetrahydrofuran) and TBAB (tetra-n-butyl ammonium bromide) in a FBR (fixed bed reactor) for pre-combustion capture of CO2. Silica sand was used as a medium to capture CO2 from CO2/H-2 gas mixture by hydrate crystallisation. Experiments were performed at different temperatures (274.2 K and 279.2 K) and 6.0 MPa to determine the total gas uptake, induction time and rate of hydrate formation. The observed trends indicated that higher driving force resulted in higher gas consumption and significantly reduced induction time. For the same driving force, higher gas consumption and shorter induction time was achieved by THF as compared to TBAB. 5.53 mol% THF attained higher gas consumption than 1.0 mol% THF whereas 3.0 mol% TBAB attained lower gas consumption than 0.3 mol% TBAB. A highest gas uptake of 51.95 (+/- 5.183) mmol of gas/mol of water and a highest rate of 51.21(+/- 8.91) mol.min(-1).m(-3) were obtained for 5.53 mol% THF at 6.0 MPa and 279.2 K. Overall, this study indicated better hydrate formation kinetics with the use of THF in an FBR configuration for CO2 capture from a fuel gas mixture. (C) 2014 Elsevier Ltd. All rights reserved.

10aCarbon dioxide capture10aClathrate process10aFixed bed reactor10aGas hydrates10aPre-combustion capture10aPromoters1 aBabu, Ponnivalavan1 aHo, Chie, Yin1 aKumar, Rajnish1 aLinga, Praveen uhttp://library.ncl.res.in/content/enhanced-kinetics-clathrate-process-fixed-bed-reactor-presence-liquid-promoters-pre-000608nas a2200157 4500008004100000245010700041210006900148260000800217300001000225490000800235100001900243700001900262700001900281700001900300856013100319 2015 eng d00aEnhanced carbon dioxide hydrate formation kinetics in a fixed bed reactor filled with metallic packing0 aEnhanced carbon dioxide hydrate formation kinetics in a fixed be cJAN a78-850 v1221 aKumar, Asheesh1 aSakpal, Tushar1 aLinga, Praveen1 aKumar, Rajnish uhttp://library.ncl.res.in/content/enhanced-carbon-dioxide-hydrate-formation-kinetics-fixed-bed-reactor-filled-metallic-packing01807nas a2200181 4500008004100000245014400041210006900185260000800254300001400262490000700276520110100283100001901384700002701403700002601430700001901456700001901475856013101494 2016 eng d00aEffect of additives on formation and decomposition kinetics of methane clathrate hydrates: application in energy storage and transportation0 aEffect of additives on formation and decomposition kinetics of m cNOV a2160-21670 v943 aMethane gas storage and transportation via clathrate hydrates is proposed to be a potential solution for large-scale energy storage. In this work, we study the formation and decomposition kinetics of methane hydrates (MH) in a laboratory-scale unstirred crystallizer. The present investigation demonstrates comparative studies of hydrate formation and dissociation kinetics in the presence of tetrahydrofuran (55.6 and 27.8mmol/mol, 5.56 and 2.78mol% THF) and sodium dodecyl sulphate (1mg/g, 0.1wt% SDS). Moreover, the storage capacity and hydrate formation kinetics in both the systems are discussed. In a recent work, enhanced methane hydrate growth in the presence of THF at close to atmospheric conditions was demonstrated. The emphasis of the current work is to study the stability of hydrates to understand dissociation kinetics by measuring the rate of hydrate decomposition at different temperatures. Hydrate stability measurements were performed at -8, -3, 2, 10, and 20 degrees C to study the decomposition rates of MH and self-preservation in presence of the two additives THF and SDS.1 aKumar, Asheesh1 aKushwaha, Omkar, Singh1 aRangsunvigit, Pramoch1 aLinga, Praveen1 aKumar, Rajnish uhttp://library.ncl.res.in/content/effect-additives-formation-and-decomposition-kinetics-methane-clathrate-hydrates-application00639nas a2200157 4500008004100000245014500041210006900186260000800255300001200263490000800275100002200283700001800305700001500323700001900338856012400357 2016 eng d00aEffect of polyvinylpyrrolidone at methane hydrate-liquid water interface. application in flow assurance and natural gas hydrate exploitation0 aEffect of polyvinylpyrrolidone at methane hydrateliquid water in cDEC a613-6220 v1861 aChoudhary, Nilesh1 aDas, Subhadip1 aRoy, Sudip1 aKumar, Rajnish uhttp://library.ncl.res.in/content/effect-polyvinylpyrrolidone-methane-hydrate-liquid-water-interface-application-flow-102098nas a2200253 4500008004100000022001400041245007600055210006900131260000800200300001400208490000700222520131000229653001501539653001901554653001601573653001301589653003301602100002601635700002201661700001901683700002301702700001901725856010001744 2016 eng d a1875-510000aEffect of the amino acid L-histidine on methane hydrate growth kinetics0 aEffect of the amino acid Lhistidine on methane hydrate growth ki cSEP a1453-14620 v353 a

In the present study, the effect of a polar amino acid, L-histidine on methane hydrate growth kinetics has been investigated. Methane hydrate formation experiments were carried out in a stirred tank reactor setup at pressure and temperature conditions of 274.15 K and 5.0 MPa respectively. Two different concentrations (0.1 and 1 wt %) of L-histidine were studied. Hydrate growth through molecular dynamic (MD) simulation was also studied; pressure and temperature conditions for the simulations were set at 10.0 MPa and 270.0 K, while the concentration of L-histidine was kept fixed at 0.94 wt %. Hydrate formation runs using MD simulation were carried out with optimal concentration of methane in water. The presence of L-histidine in the system was found to significantly enhance methane hydrate growth kinetics as compared to pure water for both experimental and MD simulation runs. Final gas consumption with 1 wt % L-histidine was found to be comparable to that with 1 wt % SDS, the most commonly used additive for hydrate promotion studies. L-histidine is a benign additive which offers considerable enhancement in methane hydrate formation kinetics and can be utilized for various hydrate based technologies such as methane storage and transport. (C) 2016 Elsevier B.V. All rights reserved.

10aAmino acid10aCrystal growth10aGas hydrate10akinetics10aMolecular dynamic simulation1 aBhattacharjee, Gaurav1 aChoudhary, Nilesh1 aKumar, Asheesh1 aChakrabarty, Suman1 aKumar, Rajnish uhttp://library.ncl.res.in/content/effect-amino-acid-l-histidine-methane-hydrate-growth-kinetics02921nas a2200265 4500008004100000022001400041245013800055210006900193260009900262300001200361490000800373520191900381653002102300653002402321653001902345653001502364653002002379653002202399100002902421700001802450700001902468700002602487700001902513856012302532 2016 eng d a0016-236100aEnhanced clathrate hydrate formation kinetics at near ambient temperatures and moderate pressures: Application to natural gas storage0 aEnhanced clathrate hydrate formation kinetics at near ambient te aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcOCT a907-9190 v1823 a

SNG (solidified natural gas) technology via clathrate hydrates is a potential method for large scale stationary storage of natural gas. Clathrate hydrate formation kinetics in presence of methane and 5.6 mol% tetrahydrofuran (THF) was investigated in an unstirred reactor configuration at moderate pressure and temperature conditions. It is well known that the presence of THF generally improves the thermodynamic stability of the resulting hydrate. In order to study the scale-up potential of this approach, kinetics of hydrate growth at temperatures close to ambient conditions and moderate pressures is required. Hydrate formation experiments were performed at three different temperatures - 283.2 K, 288.2 K and 293.2 K and at experimental pressures of 7.2 MPa, 5.0 and 3.0 MPa. Further, we report a synergistic effect of kinetic promotion of mixed methane hydrate formation by coupling THF and sodium dodecyl sulfate (SDS) at 293.2 K. For the first time, we observe rapid mixed methane/THF hydrate formation kinetics at 293.2 K in presence of just 100 ppm sodium dodecyl sulfate surfactant with methane gas uptake of 3.45 (+/- 0.17) kmol/m(3) of water in 1 h. This is also the first study to demonstrate such rapid hydrate formation kinetics with significant methane storage capacity at temperature of 293.2 K (closer to the ambient temperature). Further, substantial methane gas uptake of 3.52 (+/- 0.13) kmol/m(3) of water is possible even at reduced experimental pressure of 3.0 MPa and 283.2 K in 2 h. Minimal energy requirement in an unstirred reactor for mixed methane/THF hydrate formation storage can propel the SNG technology for large scale commercial deployment. Further improvement in the process can be achieved by optimizing the cooling requirement through innovative reactor design and operating the process in a semi-batch or continuous mode. (C) 2016 Elsevier Ltd. All rights reserved.

10aMethane hydrates10aNatural gas storage10aRapid kinetics10asurfactant10aTetrahydrofuran10aUnstirred reactor1 aVeluswamy, Hari, Prakash1 aKumar, Sharad1 aKumar, Rajnish1 aRangsunvigit, Pramoch1 aLinga, Praveen uhttp://library.ncl.res.in/content/enhanced-clathrate-hydrate-formation-kinetics-near-ambient-temperatures-and-moderate01691nas a2200169 4500008004100000245014600041210006900187260000800256300001600264490000800280520102800288100001901316700002001335700001901355700001901374856012801393 2016 eng d00aExperimental investigation to elucidate why tetrahydrofuran rapidly promotes methane hydrate formation kinetics: applicable to energy storage0 aExperimental investigation to elucidate why tetrahydrofuran rapi cDEC a29062-290680 v1203 aMethane storage as SNG (solidified natural gas) in the form of clathrate hydrates is an emerging, economically feasible and environmentally benign technology for large scale storage. Mixed tetrahydrofuran (THF)-methane (CH4) hydrates offer a paradigm shift to milder storage conditions and faster hydrate formation kinetics, providing a promising scenario to scale up the SNG technology. In this work, we synthesize mixed THF-CH4 hydrates in a high pressure microdifferential scanning calorimeter (HP mu-DSC) to elucidate the two-step hydrate formation mechanism of mixed THF-CH4 hydrate identifying the synergism between THF and CH4. Heat flow change during hydrate formation and dissociation of mixed THF-CH4 hydrates formed in the presence of 5.56 mol % THF (stoichiometric composition) were monitored. The two step-mechanism of mixed THF-CH4 hydrate formation was further confirmed by the pressure-temperature profile and visual observations with a sample volume scale -up of about 350 times that of mu-DSC experiments.1 aKumar, Asheesh1 aDaraboina, Nagu1 aKumar, Rajnish1 aLinga, Praveen uhttp://library.ncl.res.in/content/experimental-investigation-elucidate-why-tetrahydrofuran-rapidly-promotes-methane-hydrate01312nas a2200169 4500008004100000245008400041210006900125260000800194300001000202490000800212520073000220100003300950700002500983700001901008700001501027856010001042 2017 eng d00aEffect of shape of protrusions and roughness on the hydrophilicity of a surface0 aEffect of shape of protrusions and roughness on the hydrophilici cOCT a34-390 v6583 aWe have investigated wetting of model rough surfaces made up of hydrophilic triangular and hexagonal pillars (protrusions). The surface roughnesses are altered by varying the area of the rough surface, the height of the pillars, and the surface interactions to the water. We have established a correlation between structure i.e., the shape of a pillar, which actually depends on the number of edges (due to shape), and the wetting phenomena. We have found that surface with higher number of edges repels water at lower roughness value. We explain the correlation by analyzing the variation of interactions energy components and density profiles of water on the structured surfaces. (C) 2017 Elsevier B.V. All rights reserved.1 aChowdhury, Sheelan, Sengupta1 aPandey, Prithvi, Raj1 aKumar, Rajnish1 aRoy, Sudip uhttp://library.ncl.res.in/content/effect-shape-protrusions-and-roughness-hydrophilicity-surface01711nas a2200193 4500008004100000245006700041210006700108260000800175300001400183490000700197520108000204100002601284700002701310700001901337700002601356700002401382700001901406856009201425 2017 eng d00aEffects of micellization on growth kinetics of methane hydrate0 aEffects of micellization on growth kinetics of methane hydrate cAPR a3687-36980 v563 aSurfactants are Specific functional materials, that form various types of self-assemblies and affect local water ordering alongside solution properties. Such surface active agents are used extensively in gas hydrate based applications as kinetic hydrate promoters. To understand the effect of surfactant micelles on hydrate formation kinetics, a novel surfactant system capable of producing micelles at hydrate forming temperature was developed. The presence of surfactant micelles in this new system (a combination of anionic surfactant SDS and zwitterionic surfactant CAPB) was determined through DLS measurements. Pure methane and a coal bed methane mixture were individually used to assess the efficacy of the surfactant mixture for hydrate formation. This study conclusively proves for the first time that the presence of surfactant micelles enhances hydrate formation kinetics. The findings reported here can contribute significantly toward improving the utility of surfactants in gas hydrate based technological applications such as gas separation and methane storage.1 aBhattacharjee, Gaurav1 aKushwaha, Omkar, Singh1 aKumar, Asheesh1 aKhan, Muzammil, Yusuf1 aPatel, Jay, Narayan1 aKumar, Rajnish uhttp://library.ncl.res.in/content/effects-micellization-growth-kinetics-methane-hydrate01513nas a2200193 4500008004100000022001400041245010500055210006900160260000800229300001400237490000800251520082700259100002201086700002401108700001501132700002301147700001901170856013001189 2018 eng d a1520-610600aEffect of sodium dodecyl sulfate surfactant on methane hydrate formation: a molecular dynamics study0 aEffect of sodium dodecyl sulfate surfactant on methane hydrate f cJUN a6536-65420 v1223 a

In experimental studies, it has been observed that the presence of sodium dodecyl sulfate (SDS) significantly increases the kinetics of hydrate formation and the final water-to-hydrate conversion ratio. In this study, we intend to understand the molecular mechanism behind the effect of SDS on the formation of methane hydrate through molecular dynamics simulation. Hydrate formation conditions similar to that of laboratory experiments were chosen to study hydrate growth kinetics in 1 wt % SDS solution. We also investigate the effect of interactions with isolated SDS molecules on methane hydrate growth. It was observed that the hydrophobic tail part of the SDS molecule favorably interacts with the growing hydrate surface and may occupy the partial hydrate cages while the head groups remain exposed to water.

1 aChoudhary, Nilesh1 aHande, Vrushali, R.1 aRoy, Sudip1 aChakrabarty, Suman1 aKumar, Rajnish uhttp://library.ncl.res.in/content/effect-sodium-dodecyl-sulfate-surfactant-methane-hydrate-formation-molecular-dynamics-study