Response surface methodology for the optimum production of biodiesel over Cr/Ca/γ-Al2O3 catalyst: Catalytic performance and physicochemical studies

EDX mapping image profile of Cr/Ca (10:90)/Al2O3 catalyst calcined at 700 °C for 5 h [(a: alumina compound), (b: oxygen compound), (c: calcium species), (d: chromium species)].442