Agradecimentos: The authors are grateful to the São Paulo Research Foundation (FAPESP grant #2020/06315-7, grant #18/19198-9, and grant #2022/05244-4), Coordination for the Improvement of Higher Education Personnel - Brasil (CAPES) – Finance Code 001, the National Council for Scientific and Technological Development (CNPq – 306666/2020-0), and the Fund for the Support of Education, Research and Extension (FAEPEX/ UNICAMP) for the financial support. The authors are also grateful for the financial support of the Human Resources Program of the National Agency of Petroleum, Natural Gas and Biofuels - PRH-ANP, supported with funds from the investment of oil companies qualified in the PDI Clause of ANP Resolution 50/2015 (PRH 29.1 - Refer to PUBLIC NOTICE No. 1/2018 / PRH-ANP; Agreement FINEP / FUNCAMP / FEQ Ref. 5485) Ver menos

Abstract: Gas hydrates are solid solutions which cause flow assurance problems and risks to line integrity in the petroleum industry. Thermodynamic inhibitors are usually injected during production to avoid hydrate formation. In recent years, many authors have reported Ionic Liquids (ILs) as inhibitors. However, there are not many studies on thermodynamic modeling in the literature involving ILs as hydrate inhibitors, especially when it comes to the applicability of the Cubic Plus Association (CPA) and Soave-Redlich Kwong (SRK) Equation of State. In light of this, the aim of this work was to evaluate methane hydrate equilibrium in the presence of ILs as inhibitors using van der Waals-Platteeuw solid solution theory along with these Equations of State to describe liquid and gas phases. The commercial software Multiflash and its interface with excel were employed to calculate hydrate equilibrium pressures. Data from the literature on 12 imidazolium-based ILs were taken into account by varying carbon chain length and anion basicity. Both Equations of State resulted in accurate equilibrium predictions with similar deviations between calculated and experimental data (overall ARD 4.64% for CPA, and 4.49% for SRK) considering p and T conditions in the range of 2.5–35 Mpa and 272–295 K respectively. 2B association was considered for ILs, while 4C association was used for water. In general, longer cation carbon chain lengths and higher anion basicity resulted in lower accuracy Ver menos