Feasibility Study of Benzene Dehydration through an Adsorption Process: Isotherm Determination, Kinetics, and Fixed-Bed Column Studies

Abstract

The benzene dehydration process is of vital significance in the industrial scale especially in linear alkyl benzene production plants. In the present work, different zeolites were utilized for elimination of water from benzene, and their water removal efficiencies were compared. The type of adsorption isotherm for the selected adsorbent (4A zeolite) was examined, and the experimental data were well-fitted with the Langmuir isotherm. The obtained results in kinetics studies suggested that the external and overall mass transfer coefficients are improved when the stirring rate was increased up to 100 rpm and remained constant with further increase in the agitation speed. Furthermore, a continuous setup was designed for investigating the effect of operational parameters on the breakthrough curve characteristics. The highest break time (612 min) was achieved when benzene’s superficial velocity and adsorption bed’s length were set at 0.002 m/s and 30 cm, respectively. The practicability of the 4A zeolite for commercial benzene dehydration applications was verified by its acceptable performance in the reusability study with slight efficiency reduction after four adsorption/desorption cycles. According to the obtained results from breakthrough curves, the internal and external mass transfer coefficients were estimated to be of the same order of magnitude, suggesting that both mass transfer mechanisms are important. Two well-known theoretical breakthrough models including Thomas and Adams–Bohart models were employed to describe the normalized concentration profiles and the predictions of the Thomas model fitted appropriately with the experimental results. © 2021 American Chemical Society