Preparation of Nickel Oxide Supported Zeolite catalyst (NiO/Na-ZSm-5) for Asphaltene Adsorption: A Kinetic and Thermodynamic Study

Abstract

One of the important issues in oil industry is related to asphaltene precipitation during different stages, and using nanoparticles is known as a common method for solving this problems. Although nickel oxide and zeolite have been addressed in previous researches for solving asphaltene precipitation problem, Using NiO/Na-ZSm-5 (the main goal of this study) has not been developed for solving relevant asphaltene precipitation problem. The crystalline structure and morphology of the synthesized nanoparticles have been analyzed with the help of XRD, SEM, FTIR and EDX. Results show that the nanoparticles were well synthesized and after synthesis with a diameter of 13.6 nm. The EDX analyses also approved that an amount of asphaltene was adsorbed by the sorbent. Asphaltene adsorption experiments were carried out at various asphaltene concentrations and different temperatures and the effect of different variables of initial asphaltene concentrations, temperature and ratio of heptane to toluene were evaluated on asphaltene adsorption rate. The results indicate that with an increase in the initial asphaltene concentration from 25 to 2000 ppm, the asphaltene adsorption rate in zeolite increases. In concentrations less than 500 ppm, a rise in temperature results in reduced asphaltene adsorption, while at concentrations higher than 500 ppm, with a rise in temperature from 25°C to 55°C, asphaltene adsorption capacity on zeolite increases. Also greater adsorption has been observed for Heptane/Toluene=0.4 with q=25.17 mg/g. For determining the kinetic mechanism of this process, the experimental data were adapted according to Lagrangian pseudo-first and second-order models. The Langmuir and Freundlich adsorption isotherms were evaluated, in which the isotherms resulting from the Langmuir isotherm model were of adequate conformity. This indicates that adsorption at the homogenous level occurred with single-layered coating. In the final step, after evaluating the thermodynamic conditions, the spontaneity of the asphaltene adsorption process was proven.