Phase Equilibrium Data for the Hydrates of Synthesized Ternary CH₄/CO₂/N₂ Biogas Mixtures

Abstract

To enhance the energy efficiency of biogas and reduce environmental pollution, impurities such as CO2 and N2 must be removed. In this context, hydrate-based gas separation (HBGS) is a novel technology that has been utilized in gas purification. As such, the hydrate phase equilibrium data of the CH4/CO2/N2 gas mixture are crucial for application of the HBGS process in biogas separation. This study presents our investigation into the phase equilibrium conditions for the hydrates of synthesized ternary CH4/CO2/N2 biogas mixtures. All experiments were conducted at 276.2–286.3 K and 2.59–8.84 MPa using an isochoric method with different ternary CH4/CO2/N2 gas concentrations. The results obtained herein indicated that the hydrate phase equilibrium conditions shifted to lower pressures and higher temperatures with increasing CO2 contents. In addition, with a N2 content of about 10%, the hydrate phase equilibrium data of the ternary gas mixtures approached that of pure CH4.

Shift in the Raman symmetric stretching band of N2, CO2, and CH4 as a function of temperature, pressure, and density

“…They have also been identified in the atmosphere and at the surface of some celestial bodies such as Titan, an icy moon of Saturn . Furthermore, gas mixtures with similar compositions are commonly part of industrial processes, as well as in agricultural and municipal waste management, for example, in the production of biofuels that are increasingly used for generating heat and electricity . Thus, methods to analyze the physical and chemical properties of these gases and gas mixtures are needed for a variety of applications.…”

“…municipal waste management, for example, in the production of biofuels that are increasingly used for generating heat and electricity. [12,13] Thus, methods to analyze the physical and chemical properties of these gases and gas mixtures are needed for a variety of applications.…”

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

“…To date, many studies have focused on the hydrate phase equilibrium of the single-component gases (CH 4 , CO 2 , and N 2 ) in different concentrations of TBAB aqueous solutions, − in addition to studies on binary gas hydrates, including CH 4 /CO 2 and CO 2 /N 2 . ,− It was found that TBAB can significantly shift the hydrate phase equilibrium conditions to higher temperatures and lower temperatures with different gas components. However, studies focusing on hydrate phase equilibrium conditions using ternary mixture gases are still relatively scarce; few have been published to date …”

Phase Equilibria for Gas Hydrates Formed with Methane or Ethane + Tetra-n-Butylphosphonium Bromide + Water

“…9 In contrast, gas hydrates have found new potential applications nowadays, such as gas storage, especially those of natural gas 7,14,15 and hydrogen, 16 greenhouse gas capture, 17,18 ground or ocean sequestration of CO 2 , 10 seawater desalination, 2 cool energy storage for air conditioning, 19,20 development of heat pump/refrigeration systems, 20 and hydrate-based gas separations. 21,22 For these reasons, research is also now focused on the study of additives that promote the formation of gas hydrates. These are denominated thermodynamic promoters or hydrate formers and generally are water-soluble chemicals.…”

“…In contrast, gas hydrates have found new potential applications nowadays, such as gas storage, especially those of natural gas ,, and hydrogen, greenhouse gas capture, , ground or ocean sequestration of CO 2 , seawater desalination, cool energy storage for air conditioning, , development of heat pump/refrigeration systems, and hydrate-based gas separations. , …”