An investigation into the process intensification of gasoline etherification by coupling with membrane separation

The etherification of gasoline is an efficient approach to diminish the olefin content as well as improve the stability and octane number of the fuel. Nevertheless, the olefin conversion rate during the gasoline etherification process is restricted by thermodynamic equilibrium. In this study, a novel method of coupling membrane separation technology with etherification process of gasoline is utilized to overcome this equilibrium limitation by separating the reactants and products of the etherification reaction. Specifically, a polydimethylsiloxane (PDMS) tubular membrane is employed to treat actual etherified gasoline with pressure-driven and cross-flow mode. The inherent hydrophobicity of PDMS membrane results in a preference of reactant active olefins with stronger hydrophobicity in the etherified gasoline for permeating the membrane. In contrast, the PDMS membrane preferentially retains product ether compounds in the etherified gasoline due to their lower hydrophobicity and higher molecular weights. This indicates that the primary separation mechanism for the components in etherified gasoline is their affinity differences to the PDMS membrane. In addition, transmembrane pressure and cross-flow rate are demonstrated both have the greatly effect on the PDMS membrane performance. Compared with the gasoline etherification reaction process in a fix-bed reactor, the introduction of membrane separation technology increases the C5 active olefin conversion rate in gasoline by 11.8%. This study presents a robust approach to enhance the gasoline etherification process by selectively separating reactants and products. This method holds significant implications for the advancement of the gasoline etherification technology.