Adsorption Mechanism of Fluorinated Hydrocarbon Gas Tracers (R134a) on Metal–Organic Frameworks (M‐MOF‐74, M = Mg, Ni, Co) as Novel Adsorbents

ABSTRACT In the process of oil and gas field development, gas tracer technology can obtain various information about oil and gas reservoirs, thereby providing a basis for the formulation and adjustment of development plans. However, the low storage efficiency and high transportation risks of gas tracers significantly impact the detection efficiency. Metal–organic frameworks (MOFs), as a class of porous materials with excellent adsorption properties, offer a potential solution to the issues associated with the storage and transportation of gas tracers. In this study, a new series of M‐MOF‐74 (M = Mg, Ni, Co) materials, exhibiting high R134a adsorption performance, were synthesized via an improved solvothermal method. The interactions between M‐MOF‐74 (M = Mg, Ni, Co) and R134a were investigated through a combination of inverse gas chromatography (IGC) and density functional theory (DFT) calculations. To assess the surface properties, a range of polar and nonpolar probes were employed to determine the surface‐dispersive free energy and Lewis acid–base constants of M‐MOF‐74 over a temperature range of 343.15–383.15 K. The results revealed that the surface dispersion free energy of M‐MOF‐74 (M = Mg, Ni, Co) decreases with increasing temperature, with the materials exhibiting amphoteric characteristics, trending toward acidity. The adsorption mechanism of M‐MOF‐74 toward R134a was further elucidated using DFT calculations. Analysis of frontier orbital distributions (HOMO–LUMO), electrostatic potential (ESP), and reduced density gradient (RDG) showed that the surface acidity and basicity of M‐MOF‐74 arise from the inhomogeneous distribution of surface charges. These findings suggest that R134a preferentially adsorbs onto the atoms surrounding the unsaturated metal sites of MOF‐74, with Ni‐MOF‐74 demonstrating a significantly stronger adsorption capacity for R134a. This work provides valuable insights into the mechanisms of R134a adsorption in MOFs.