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Gas separation is a critical application of gas hydrates, and accurately predicting separation performance is crucial. In this study, we used thermodynamic calculations to predict the equilibrium phase of gas hydrates for various mole fractions of CO2 + CH4 gas mixtures. We also determined the mole fraction of each gas component trapped within the hydrate clathrate. To predict the equilibrium points, we used the Soave–Redlich–Kwong（(SRK) equation of state for the gas phase, the nonrandom two-liquid (NRTL)model for the liquid phase, and the Chen–Guo model for the hydrate phase. We modified the hydrate fugacity formula and introduced a new function to improve the accuracy of the Chen–Guo model. By incorporating experimental equilibrium results from our study and another study, we developed a correlation based on gas mixture composition and temperature, resulting in highly accurate predictions. The use of this new correlation for hydrate fugacity calculation significantly improved precision, as evidenced by an average absolute deviation percent of calculated pressures (AADP) of 1.34% for pure CO2 and 1.25% for CH4. When considering the 27 data points of different CO2 + CH4 mixtures, the AADP% was 1.98%.To implement the model to predict equilibrium phases, we used the Chen–Guo framework to determine the mole fraction of each gas component in the hydrate mixture. Interestingly, we discovered a linear correlation between the CO2 mole fraction in the hydrate and equilibrium pressure, with a slope of approximately 0.001 and a y-intercept of less than one, for all gas compositions. Therefore, we can conclude that low thermodynamic conditions (temperature and pressure) result in a high CO2 mole fraction in the hydrate phase and great separation efficiency.

One important technique of producing ultra‐clean fuel or value‐added chemicals is through Fischer‐Tropsch synthesis. The solubility of synthesis gases (H2 and CO) in the liquid phase is a significant aspect, which paves the way for evaluation of the product's distribution during the process. In this work, a complete equation has been developed that can predict the solubility of syngas in line with experimental data. The majority of average absolute deviation (AAD) of results was lower than 2.5 %. In addition, the effect of thermodynamic parameters, i.e., pressure and temperature, and the H2/CO ratio is considered in this equation by four different factors. The impact of pressure on syngas is divided into two adjustment components, denoted as n1 for CO and n2 for H2. The subsequent factor is n3, which illustrates how temperature affects the solubility of syngas. Further, the n represents the H2‐to‐CO feed ratio impacts on syngas solubility. Considering these factors and their mutual interactions allows for evaluating syngas solubility and chain growth accurately. [ABSTRACT FROM AUTHOR]

• Experiment design was used as a new approach to hydrate phase equilibrium determination. • An response equation for hydrate equilibrium pressure at a given temperature was obtained. • The equation is based on two variables of CO 2 /CH 4 gas composition and TBAB concentration. • Using a natural log transformation of the response yielded better results for pressure calculation. • The equation was validated by comparing the model to actual hydrate phase equilibrium points. In this study, we introduce experimental design as a novel approach to derive an equation that predicts the hydrate phase equilibrium temperature in a L W –H–V (liquid water, hydrate, vapor) system, based on pressure, gas composition, and the concentration of tetra- n -butylammonium bromide (TBAB). Our phase equilibria model is informed by experiments under nine different conditions, varying in gas compositions (CH 4 , CO 2 , and a 50/50 mole % CH 4 /CO 2 mixture) and TBAB concentrations (15 and 30 wt.%). From these, we calculated temperature responses for 13 experiments, leading to the formulation of two models: a model without pressure transformation, which lacked predictive accuracy, and a more accurate model incorporating a natural logarithm pressure transformation (NLPT). The NLPT model demonstrated exceptional predictive power, with R 2, adjusted R 2, and predicted R 2 values of 0.9975, 0.9958, and 0.9914, respectively. Additionally, it achieved an F -value of 565.90 in the analysis of variance (ANOVA). Validation diagrams, comparing predicted results to experimental data, confirmed the ability of the NLPT model to accurately predict hydrate phase equilibria, underscoring the efficacy of our experimental design approach. [Display omitted] [ABSTRACT FROM AUTHOR]