The widespread use of methane (CH4) as a bridging fuel to transition into a carbon-constrained world necessitates the need to develop safe, reliable and efficient technology for large-scale CH4 storage. Solidified natural gas (SNG) technology via clathrate hydrates can store large volumes of CH4 at mild storage conditions (atmospheric pressure and moderate temperatures) compared to compressed natural gas (CNG) or adsorbed natural gas (ANG). Slow hydrate growth kinetics and stability of hydrates at moderate temperatures are two challenges that need to be mitigated in order to commercialize SNG technology. In this work, we characterize the mixed (methane-tetrahydrofuran) hydrate formation by analyzing solid hydrate phase highlighting temporal changes of the cage occupancy using in-situ Raman spectroscopy complemented by measuring the CH4 uptake along with visual observations. Powder X-ray diffraction (PXRD) characterization of synthesized hydrates confirms the presence of only sII structure. We also demonstrate the stability of the sII mixed (CH4-THF) hydrates at near atmospheric pressure for a time period of two months. © 2018 Elsevier Ltd

Rajnish Kumar

Department Of Chemical Engineering

Atmospheric pressure

COMPRESSED NATURAL GAS

Energy Storage

Fuel storage

Gases

Growth kinetics

Hydration

Methane

Organic solvents

Raman spectroscopy

stability

ADSORBED NATURAL GAS

COMPRESSED NATURAL GASSES (CNG)

Efficient technology

HYDRATE STABILITIES

IN-SITU RAMAN SPECTROSCOPY

METHANE STORAGE

POWDER X-RAY DIFFRACTION (PXRD)

TETRAHYDROFURAN HYDRATE

Gas hydrates

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IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

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IIT Madras

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Methane storage in mixed hydrates is advantageous due to faster kinetics and added stability. However, capacity needs to be improved. Here we study mixed hydrates of methane (CH4) and tetrahydrofuran (THF), in the presence of sodium dodecyl sulfate (SDS) as a kinetic promoter for hydrate formation. We report the co-existence of pure methane (sI) and mixed CH4-THF hydrates (sII) in the presence of SDS; however, in the absence of SDS, co-existence of pure THF (sII) and mixed CH4-THF hydrates (sII) was observed. Thus the presence of SDS preferentially promotes the enclathration of methane over that of THF. Furthermore, through in situ Raman spectrometry, complemented by high-pressure differential scanning calorimeter, we present temperature-dependent methane occupancy in small and large cages of sI and sII hydrates. Our findings offer new insights for enhancing the methane storage capacity in more stable sII hydrate configuration for large-scale methane storage via solidified natural gas technology. Chemistry; Chemical Engineering; Separation Science © 2019 The Author(s)

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Sodium Dodecyl Sulfate Preferentially Promotes Enclathration of Methane in Mixed Methane-Tetrahydrofuran Hydrates

Kinetic studies concerning the combination of thermodynamic promoters (tetra-n-butyl ammonium bromide, TBAB and tetrahydrofuran, THF) and kinetic promoters (sodium dodecyl sulphate, SDS) have not yet been investigated in detail for methane hydrate system suitable for natural gas storage and transportation. In this work, experiments were conducted at an initial pressure conditions of 7.5&nbsp;MPa and 276.15&nbsp;K for pure water, SDS, TBAB, (TBAB&nbsp;+&nbsp;SDS), THF, (THF&nbsp;+&nbsp;SDS) and (THF&nbsp;+&nbsp;TBAB) aqueous systems for various concentrations. Similarly, at 5.5&nbsp;MPa and 276.15&nbsp;K, experiments were conducted for pure water, TBAB, (TBAB&nbsp;+&nbsp;SDS), THF and (THF&nbsp;+&nbsp;SDS) aqueous systems for various concentrations. In addition, at 3.0&nbsp;MPa and 276.15&nbsp;K, 0.05 and 0.1 mass fraction of TBAB, 0.005 and 0.01 mass fraction of THF and (0.01&nbsp;+ 0.1) mass fraction of (THF&nbsp;+ TBAB) aqueous systems have been considered for the experiments. It has been observed that the methane hydrate formed from pure water with SDS shows higher moles of gas consumption per mole of water as compared to other aqueous systems at higher pressure. Also, the use of SDS with THF shows drastic increase in methane consumption as against semiclathrate hydrate/hydrate formed using TBAB aqueous system and pure water. At lower pressure, of about 3&nbsp;MPa, gas consumption per mole of water in hydrate has found to enhance for a mixed promoter system containing (THF&nbsp;+ TBAB) as compared with the other aqueous systems. Theoretical and actual gas storage capacity calculations has also been performed for various concentrations of THF and TBAB aqueous systems. This study essentially helps to understand the behaviour of TBAB and THF aqueous solution with and without SDS and mixed promoter system of (THF&nbsp;+&nbsp;TBAB) for methane hydrate formation desirable for applications like gas storage, transportation and gas recovery using hydrate-based gas separation method. © 2016 Elsevier B.V.

Journal of Natural Gas Science and Engineering

Kinetics of methane hydrate formation in an aqueous solution of thermodynamic promoters (THF and TBAB) with and without kinetic promoter (SDS)

Applied Energy

A review of solidified natural gas (SNG) technology for gas storage via clathrate hydrates

The Journal of Physical Chemistry C

Experimental Investigation To Elucidate Why Tetrahydrofuran Rapidly Promotes Methane Hydrate Formation Kinetics: Applicable to Energy Storage

The Canadian Journal of Chemical Engineering

Effect of additives on formation and decomposition kinetics of methane clathrate hydrates: Application in energy storage and transportation

Enhanced clathrate hydrate formation kinetics at near ambient temperatures and moderate pressures: Application to natural gas storage

Molecular level investigations and stability analysis of mixed methane-tetrahydrofuran hydrates: Implications to energy storage

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Publisher	Data powered by TypesetElsevier Ltd
ISSN	00162361
Open Access	No