An Approach for Determining the Absolute Adsorption Capacity of n-Paraffin on 5A Molecular Sieve From Liquid Phase

ISSN： 1091-6466

Source： Petroleum Science and Technology, Vol.29, Iss.18, 2011-07, pp. : 1912-1921

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Abstract

5A molecular sieves are widely used as adsorbents for separating n-paraffins from their isomers. An inert-component method is designed for determining the absolute adsorption capacity of 5A molecular sieves accurately. The total adsorption capacity of n-paraffin in binary solution on 5A molecular sieves includes two parts: the wetting capacity and absolute adsorption capacity. An inert component is used to calculate the wetting capacity, and the absolute capacity is then the gap of the total capacity and the wetting capacity. The absolute adsorption capacities of n-hexane, n-heptane, and n-octane on 5A molecular sieves are therefore determined by this method at 298 K, which are 0.108, 0.107, and 0.111 g/g, respectively. The measured results show better accuracy compared to the adsorption capacities reported. Based on the inert-component method for the absolute adsorption capacity, the liquid-phase adsorption isotherms of n-hexane, n-heptane, and n-octane on 5A zeolite at 298 K are obtained and fitted with the Langmuir model.