Effect of Hydrogen Bonding Energy and Freezing Point Depression of Quaternary Ammonium Salts on the Thermodynamic Gas Hydrate Inhibition

Theeffects of the hydrogen bonding energy interactionand freezingpoint depression on five quaternary ammonium salts (QAS) of gas hydratesystems are discussed in this study. Tetramethylammonium bromide,tetraethylammonium bromide, tetramethylammonium acetate, tetraethylammoniumacetate tetrahydrate, and tetramethylammonium iodide were among theQAS studied. Methane (CH4) and carbon dioxide (CO2), frequently encountered in flow assurance pipelines, are includedin the considered hydrate system. The experimental temperature rangeis 274-285 K, with 3.40-8.30 and 2.0-4.0 as thecorresponding pipeline pressures for CH4 and CO2. For different mass concentrations (1, 5, and 10 wt.%), the thermodynamicinfluence, i.e., average suppression temperature (& UDelta; T ), of the studied system was reported, and itsrelationship with the hydrogen bonding energy (E (HB)) interaction and freezing point temperature (T (f)) of QAS was investigated. The structural impact of QAS(in the form of alkyl chain variation) and anions on thermodynamichydrate inhibition (THI) behavior via hydrogen bonding energy interactionsand freezing point is also covered in the research. According to thefindings, the increase in the alkyl chain length of QAS reduced thedecrease in E (HB) bonding ability. On theother hand, the presence of an anion had a significant impact on QAS.The E (HB) and QAS freezing T (f) are concentration-dependent phenomena; higher QAS concentrationin the system resulted in lower T (f) temperaturesand higher E (HB) energies, which influencedhydrate mitigation positively. The work is novel as it establishesthe relationship between E (HB) and averagesuppression temperature and also between depression in freezing pointwith average suppression temperature. Since QAS are considered amongpotential THI inhibitors, further development is required for a generalizedcorrelation based on the E (HB) interactionand T (f).

Automated summary

This study discusses the effects of hydrogen bonding energy interaction and freezing point depression on five quaternary ammonium salts (QAS) in gas hydrate systems. Methane and carbon dioxide, commonly encountered in flow assurance pipelines, are included in the studied hydrate system. The study reports the thermodynamic influence, average suppression temperature, of the studied system for different mass concentrations and investigates its relationship with the hydrogen bonding energy interaction and freezing point temperature of QAS. The work establishes the relationship between hydrogen bonding energy and average suppression temperature, as well as depression in freezing point with average suppression temperature.