Recent advancements in micro-flow technologies and a drive toward more efficient, greener and safer processes have led to a renaissance in flow-chemistry for pharmaceutical production.

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A poly­(phenylene sulfide) (PPS) catalytic membrane (PPSCM) was prepared through a heterogeneous sulfonation of PPS nonwoven fabrics with sulfur trioxide (SO3) as a sulfonation agent under mild conditions to catalyze the reaction of oleic acid with methanol in a flow-through mode. The results of X-ray photoelectron spectrometer (XPS) proved that each repeated unit of PPS on the fiber surface was attached to one sulfonic acid group. The hydrogen ion-exchange capacity (IEC) of the PPSCM increased with SO3 concentration and hardly changed with reaction time. As the IEC increased, the specific surface area of the PPSCM became 2 orders of magnitude higher than that of the fabrics before sulfonation and the pore size and mechanical properties of the PPSCM were decreased. The PPSCM was used in the continuous esterification reaction of oleic acid with methanol in a flow-through mode. The conversion reached a maximum of 98.0% under the conditions of the reaction temperature of 65 °C, the residence time of 2104 s, and the methanol/oleic acid mass ratio of 3:1. Moreover, the PPSCM showed good catalytic stability with a conversion of above 95% for 50 h in a flow-through mode. The results indicated that the PPSCM was a promising solid-acid catalyst for biodiesel production.