Stability Determination of the Modified Activated Carbon to Adsorb Thiophenic Compounds from Model Diesel Fuel

The main objective of this research is stability determination of activated carbon adsorbent at fixed bed adsorption column for desulfurization of diesel fuel by mathematical modeling. This model is based on mass balances. Equations that are the outcome of mass balances are known as the second degree of partial differential equations, and they must be solved together simultaneously to generate appropriate breakthrough curves at the end of the bed. On the other hand, running momentum balance by using some assumptions, lead to the Ergun equation which clearly represents pressure drop through adsorption bed. The mentioned equations have been solved simultaneously in MATLAB software and the solution method was the finite difference. After ensuring the validity of the model, scaling up is done to determine adsorbent stability and quantify its performance in an industrial dimension bed. Then the effective parameters on the bed operation and adsorbent stability were identified. Also, the batch adsorption isotherm experiments were carried out at room temperature to determine the maximum capacity of adsorbent in sulfur compound adsorption. Using capped bottles containing 10 mL solutions which contain dibenzothiphen (DBT) dissolved in n-decane and 0.1 g of activated carbon that were equilibrated for 5 hours. Concentrations of Thiophenic Compound (TC) solutions were 330,462,660,990, and 1,320 mg/L of TC. The experiment method was according to some author’s studies. The fluid velocity and mass transfer resistance for diffusion in adsorbent’s pores are the most important parameters in adsorption bed’s behavior and generating of breakthrough curves. The lowest the fluid velocity, the more time the fluid stays in bed and the bed's efficiency raises in terms of pollutant removal accordingly, as well as bed saturated in a longer time.