Batch and Continuous Adsorptive Desulfurization of Model Diesel Fuels Using Graphene Nanoplatelets

An experimental investigation on adsorptive desulfurization for model diesel fuels (MDFs) is described using graphene nanoplatelets (GNPs) as an adsorbent. Batch experiments for a single component as well as a multicomponent system were conducted. The single-component adsorption isothermal experimental results for the batch process were well represented by the Freundlich isotherm (thiophene (T), 2-methylthiophene (2-MT)) and the Langmuir isotherm (dibenzothiophene (DBT)) models. The adsorption process kinetics fits with the pseudosecond-order model for T, 2-MT, and DBT on GNPs. Both surface and pore diffusions controlled the sorption process. A process design of a single-stage batch-adsorber for the adsorption of T, 2-MT, and DBT onto GNPs was also studied using the calculated adsorption isotherm parameters. In addition, a fixed-bed adsorber was used for studying the continuous system at ambient conditions for multicomponent MDFs. The main objective of continuous studies was to investigate the process variables' effect on the desulfurization. The effect of flow rate, bed height, and initial sulfur concentration on the adsorptive capacity of the adsorbent for T, 2-MT, and DBT were evaluated. The breakthrough time and adsorptive capacity increased with increasing the bed height and decreasing the flow rate and initial sulfur concentration. For continuous studies, more than 90% of the bed was saturated for all thio-compounds within 100 min for the feed flow rate of 3 mL/min and adsorbent weight of 3 g. The Adam-Bohart model was used to check the performance of the adsorption breakthrough curves. The Adam-Bohart model rate constant and adsorption capacity were found to be 0.006 (mg/kg)(-1) h(-1) and 117.21 mg S/kg, respectively.