Adsorption-based removal of mercaptans from gas condensates using Al-MCM-41: synthesis, characterization, kinetics, and mechanistic insights

Abstract This study reports the synthesis, characterization, and performance evaluation of an aluminum-incorporated MCM-41 (Al-MCM-41) adsorbent for the removal of mercaptans from natural gas condensate. To the best of our knowledge, this study represents the first evaluation of Al-MCM-41 for mercaptan removal from real gas condensate, using South Pars gas condensate as a realistic hydrocarbon feed under near-industrial laboratory conditions. The adsorbent was prepared via a direct hydrothermal method and characterized by nitrogen sorption measurements Brunauer–Emmett–Teller (BET surface area 731 m2/g), XRD, FTIR, and SEM–EDS. Batch adsorption experiments were conducted under optimal conditions (65 °C, atmospheric pressure, 0.1 g adsorbent in 10 mL condensate) using a real sample from the South Pars gas field containing 3000 ppm total sulfur (2000 ppm mercaptans).The adsorbent achieved a maximum adsorption capacity of 120 mg g⁻1, corresponding to approximately 60% mercaptan removal, with adsorption equilibrium reached within 3 h . The Freundlich isotherm (R2 > 0.999) indicated multilayer adsorption on a heterogeneous surface, while pseudo-first-order kinetics (R2 > 0.99) and the Boyd model confirmed external film diffusion as the rate-limiting step. The activation energy (47.76 kJ mol⁻1), together with the observed increase in adsorption capacity with increasing temperature, indicates that the adsorption process is thermally favored under the investigated conditions . The adsorbent showed stable performance over a wide concentration range and retained 85% of its initial capacity after five regeneration cycles. These findings demonstrate the applicability of Al-MCM-41 for mercaptan removal from real South Pars gas condensate and provide mechanistic insights into the adsorption process in complex hydrocarbon matrices, thereby supporting the development of mesoporous silica adsorbents for practical gas-condensate desulfurization.