Effects of thermodynamic inhibitors on the dissociation of methane hydrate: a molecular dynamics study.

نویسندگان

  • Takuma Yagasaki
  • Masakazu Matsumoto
  • Hideki Tanaka
چکیده

We investigate the effects of methanol and NaCl, which are known as thermodynamic hydrate inhibitors, on the dissociation kinetics of methane hydrate in aqueous solutions by using molecular dynamics simulations. It is shown that the dissociation rate is not constant but changes with time. The dissociation rate in the initial stage is increased by methanol whereas it is decreased by NaCl. This difference arises from the opposite effects of the two thermodynamic inhibitors on the hydration free energy of methane. The dissociation rate of methane hydrate is increased by the formation of methane bubbles in the aqueous phase because the bubbles absorb surrounding methane molecules. It is found that both methanol and NaCl facilitate the bubble formation. However, their mechanisms are completely different from each other. The presence of ions enhances the hydrophobic interactions between methane molecules. In addition, the ions in the solution cause a highly non-uniform distribution of dissolved methane molecules. These two effects result in the easy formation of bubbles in the NaCl solution. In contrast, methanol assists the bubble formation because of its amphiphilic character.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

A Fugacity Approach for Prediction of Phase Equilibria of Methane Clathrate Hydrate in Structure H

In this communication, a thermodynamic model is presented to predict the dissociation conditions of structure H (sH) clathrate hydrates with methane as help gas. This approach is an extension of the Klauda and Sandler fugacity model (2000) for prediction of phase boundaries of sI and sII clathrate hydrates. The phase behavior of the water and hydrocarbon system is modeled using the Peng-Robinso...

متن کامل

Investigation of isomorph-invariance in liquid methane by molecular dynamics simulation

In this paper, isomorph invariance of liquid methane is investigated by means of constant-NVT molecular dynamics simulations. According to the data extracted from simulations, equilibrium fluctuations show strong correlation between potential energy U and virial W. We also generated isomorph state points and investigated invariance of certain thermodynamic, structural, and dynamical properties....

متن کامل

Origin of Self-preservation Effect for Hydrate Decomposition: Coupling of Mass and Heat Transfer Resistances

Gas hydrates could show an unexpected high stability at conditions out of thermodynamic equilibrium, which is called the self-preservation effect. The mechanism of the effect for methane hydrates is here investigated via molecular dynamics simulations, in which an NVT/E method is introduced to represent different levels of heat transfer resistance. Our simulations suggest a coupling between the...

متن کامل

Mechanical instability of monocrystalline and polycrystalline methane hydrates

Despite observations of massive methane release and geohazards associated with gas hydrate instability in nature, as well as ductile flow accompanying hydrate dissociation in artificial polycrystalline methane hydrates in the laboratory, the destabilising mechanisms of gas hydrates under deformation and their grain-boundary structures have not yet been elucidated at the molecular level. Here we...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Physical chemistry chemical physics : PCCP

دوره 17 48  شماره 

صفحات  -

تاریخ انتشار 2015