A stable mesoporous super-acid nanocatalyst for eco-friendly synthesis of biodiesel

•A stable mesoporous super-acid catalyst is prepared by using double-chain quaternary ammonium.•3-Fold ionic sulfates absorbed on the surface promote the stability of active sites.•Brönsted acid sites in the catalyst are active phases.•The position of H+ lies on the configuration of sulfate species.•Oil conversion is still 86.5% after five (trans)esterification runs at 140 °C.