Assessment of Hydrate Formation, Storage Capacity, and Transport Properties of Methane and Carbon Dioxide through Functionalized Carbon Nanotube Membranes

Abstract

The present work investigates the gas hydrates, storage, and transport properties of methane (CH4) and carbon dioxide (CO2) across carbon nanotubes (CNTs) designed by CONH2 (aquaporin, AQP selective filter), H2O2, and COOH functional groups via molecular dynamics (MD) simulations. Two separate systems of water–CH4 and water–CO2 at different mole fractions have been considered. The main goal is to discuss, for the first time, the gas hydrate formation mechanism in the membrane technology framework as a promising approach to mitigate the drawbacks in traditional hydrate technologies. Our model membranes offer very high CH4 storage capacity concerning available experiments. The hydrate cages decrease since the mole fraction increases (or water loading decreases), suggesting a significant contribution of water hydrogen-bonded in the hydrate formation process. The CNT-CONH2 and CNT-H2O2 model membranes provide higher hydrate cage numbers compared to CNT-COOH, suggesting a better performance for CNT-CONH2. The CNT-CONH2 shows a higher hydrate cage in the presence of CO2, particularly at the small mole fraction, while CNT-COOH and CNT-H2O2 are good at the large mole fraction. Regardless of the gas type (CH4 or CO2), both CNT-CONH2 and CNT-H2O2 model membranes suggest better performance in gas hydrate formation. Moreover, our simulated model membranes indicate better efficiency in the formation of gas hydrates concerning available experiments. An enhancement in hydrate formation in the presence of CH4 was also found in the CNT-CONH2 and CNT-H2O2 model membranes concerning the bulk system, suggesting a better performance for CNT-CONH2. This finding could reflect the potential of the membrane-based hydrate formation over the bulk system. The transport properties of water/CH4/CO2 across the model membranes have also been discussed.

Comprehensive Review and Perspectives of CO2 Hydrate Storage in Subseafloor Saline Sediments: Formation, Stability, and Optimization Strategies

“…CO 2 hydrate structural analyses, including examining F4 order parameters, mean square displacement (MSD), and hydrate cages, provide detailed insights into the system’s molecular structure and dynamics changes in electrical heating systems. , The F4 order parameter represents alterations in the structural characteristics among water molecules during hydrate formation, offering insights into the proximity of the hydrogen bonding network to the crystal structure. , This parameter can be determined analytically by computing the dihedral angle formed by two neighboring water molecules within the system, as specified in eq . The mean F4 order parameter values for water molecules in hydrate, liquid water, and ice are recorded as 0.7, – 0.04, and −0.4, respectively. , The positive value for hydrate indicates a stronger correlation between water molecules than liquid water, while the negative values for liquid water and ice suggest weaker correlations. , These values align with the expected behavior of water molecules in different phases.…”

Investigation of small inhibitor effects on methane hydrate formation in a carbon nanotube using molecular dynamics simulation

“…Understanding the transport of gases and their physiochemical interactions in nano-connements is very important because this knowledge enables us to prepare more efficient strategies for gas storage processes at the nano-scale environments. 15 The mechanism of multi-scale shale gas formation and the gas transmissibility in the process of shale gas recovery are some of the most relevant examples that need further investigations. 15,16 Among different nanopores, carbon nanotubes (CNTs) have received much attention in scientic research in recent years because of their unique physical properties and important potential applications.…”

“…15 The mechanism of multi-scale shale gas formation and the gas transmissibility in the process of shale gas recovery are some of the most relevant examples that need further investigations. 15,16 Among different nanopores, carbon nanotubes (CNTs) have received much attention in scientic research in recent years because of their unique physical properties and important potential applications. Many of these applications are associated with gas absorption and high-rate owing gases through the nanopores.…”

“…Many of these applications are associated with gas absorption and high-rate owing gases through the nanopores. 15,17,18 Moreover, an important and urgent subject that is given less attention is the potential of CNT channel membranes for gas hydrate formation. 15 Recently, Zhao et al 1 studied the formation of H 2 hydrates in carbon nanotubes.…”

“…15,17,18 Moreover, an important and urgent subject that is given less attention is the potential of CNT channel membranes for gas hydrate formation. 15 Recently, Zhao et al 1 studied the formation of H 2 hydrates in carbon nanotubes. They found that the hydrogen molecules in the gas hydrate structures are contained in a one-dimensional nanochannel, in which the guest hydrogen molecules create a molecular wire.…”