Abstract:

For separating normal paraffins in naphtha through the adsorption process using 5A molecular sieves, the ideal adsorption solution model for the mixed gas adsorption process has been improved based on the experimental data.The constant-capacity ideal adsorption solution(CIAS) model for the normal paraffins-5A molecular sieves system was established.The model could predict the equilibrium of n-C⁰₄—n-C⁰₁₀ mixed gas in 5A molecular sieves at various temperatures and pressures.The individual equilibrium adsorption capacities of n-C⁰₄—n-C⁰₁₀ and the effects of the pressure on the capacities could be calculated.So the interactions between the normal paraffins with different carbon numbers were discovered in view of thermodynamics, and the competing adsorption behavior of n-C⁰₄—n-C⁰₁₀ could be explained.The total equilibrium adsorption quantity of n-C⁰₄—n-C⁰₁₀ in naphtha predicted by CIAS model was 4%—8% greater than the experimental equilibrium adsorption quantity.The CIAS model also can be used for the mixed gas adsorption process, in which the individual equilibrium adsorption capacities of the adsorbates are approximately the same.