preparation of nickel oxide supported zeolite catalyst (nio/na-zsm-5) for asphaltene adsorption: a kinetic and thermodynamic study

one of the critical issues in the oil industry is related to asphaltene precipitation during different stages, and using nanoparticles is known as a standard method for solving this problem. although nickel oxide and zeolite have been addressed in previous research to solve the asphaltene precipitation problem, using nio/na-zsm-5 (the primary goal of this study) has not been developed to solve relevant asphaltene precipitation problems. the crystalline structure and morphology of the synthesized nanoparticles were analyzed with the help of x-ray diffraction spectrometry (xrd), scanning electron microscopy (sem), fourier transform infrared spectroscopy (ftir), and energy-dispersive x-ray spectroscopy (edxs). the results show that the nanoparticles were well synthesized and preserved their crystalline structure with a diameter of 13.6 nm after synthesis. the edxs analyses also proved that the sorbent adsorbed an amount of asphaltene. in the next step, asphaltene adsorption experiments were carried out at various concentrations of asphaltene and temperatures, and the effect of different variables, including the initial concentration of asphaltene, temperature, and the ratio of heptane to toluene, on the asphaltene adsorption rate was evaluated. the results indicate that with an increase in the initial asphaltene concentration from 25 to 2000 ppm, the asphaltene adsorption rate in zeolite increases. at concentrations less than 500 ppm, a rise in the temperature reduces the asphaltene adsorption, while at concentrations higher than 500 ppm, raising the temperature from 25 to 55 °c increases asphaltene adsorption capacity on zeolite. further, more significant adsorption is observed at a heptane-to-toluene ratio of 0.4 with q = 25.17 mg/g. evaluating the effects of kinetic adsorption molecules of asphaltene on these nanoparticles shows that the adsorption process reaches equilibrium in less than 2 h. the experimental data were adapted according to lagrangian pseudo-first-order and pseudo-second-order models to determine the kinetic mechanism of this process. the langmuir and freundlich adsorption isotherms were evaluated, and the isotherms resulting from the langmuir isotherm model were of good conformity, indicating that adsorption at the homogenous level occurred with a single-layered coating. in the final step, after evaluating the thermodynamic conditions, the spontaneity of the asphaltene adsorption process was proved.