Experimental Measurement of Phase Equilibrium of Hydrate in Water + Ionic Liquid + CH₄ System

Abstract

With the goal of discovering a more effective type of thermodynamic hydrate inhibitors (THIs), the phase equilibrium conditions of CH 4 hydrates were examined in the presence of morpholinium and piperidinium ionic liquids (ILs) at a mass fraction of 0.1. It was observed that the addition of ILs shifted the hydrate equilibrium conditions toward higher pressure and lower temperature compared with those of hydrates formed from pure water. Both cationic and anionic species influenced the equilibrium conditions of the CH 4 hydrate. The piperidinium ILs showed better inhibition effect than did the morpholinium ILs at the same species of counteranions. The result may be due to the more hydrophobic nature of piperidinium ILs, which have a higher affinity for CH 4 molecules. It was also seen that the inhibition effect of BF 4 − ions was stronger than that of Br − ions for both piperidinium and morpholinium ILs. Thus, the inhibition effect became stronger in the order:). The best among these ILs had inhibition effectiveness comparable with ethylene glycol and triethylene glycol, which are used commercially as THIs.

Effect of EMIM-BF4 Ionic Liquid on Dissociation Temperature of Methane Hydrate in the Presence of PVCap: Experimental and Modeling Studies

“…They have low melting points of about 100 °C, which means that they are liquid below that temperature . The most common ILs consist of a big heterocyclic nitrogen containing cation and both organic anions (e.g., nitrate or methanesulfonate) and inorganic anions (such as halide, dicyanamide, BF 4 – , PF 6 – ). , Lately, some research works ,− have shown that some kinds of ILs have dual functionality in gas hydrate inhibition. ILs can act as THIs and KHIs simultaneously owing to their electrostatic charges and the possibility of forming hydrogen bonds through their cations and/or anions with water. , …”

Phase Equilibria of the Synthesized Ternary CH4/CO2/N2 Mixed-Gas Hydrates in Tetrabutylammonium Bromide Aqueous Solutions at Different Concentrations

“…Meanwhile, the graphical method used was to keep the internal volume ( V ) constant while changing the other two parameters ( P and T ) to form/decompose hydrate. Pressure and temperature variations were then recorded during the entire experiment. − First, the reactor cell was vacuumed and different concentrations of TBAB solution were added to the reactor. Then, the reactor cell was vacuumed again.…”

Kinetic Effects of Ionic Liquids on Methane Hydrate

“…Most of them are nontoxic, nonflammable, thermally stable, and environmentally friendly. , Due to their tunable properties, they have gained great attention in various application areas. − As ILs are a type of salt, their thermodynamic inhibition performance is quite promising. A great amount of related research work has been done recently. ,− However, as a kind of THIs, limited research could be found.…”