K- and Cu-doped CaTiO3-based nanostructured hollow spheres as alternative catalysts to produce fatty acid ethyl esters as potential biodiesel

LANFREDI, S., MATOS, J., DA SILVA, S.R., DJURADO, E., SADOUKI, A.S., CHOUAIH, A., POON, P.S., GONZÁLEZ, E.R.P., NOBRE, M.A.L.:
Applied Catalysis B: Environmental, Volume 272, 2020, 118986.

DOI: 10.1016/j.apcatb.2020.118986

Abstract

New functional polycation oxide-type catalysts were synthesized by the ultrasonic spray-pyrolysis method. The catalytic activity in the production of fatty acid ethyl esters (FAEE’s) using soybean oil was studied. Catalysts are conformed by nanostructured hollow spheres of low density with a stoichiometric formula Ca_1-xK_xTiCu_x/2O₃. The influence of the substitutional ratio (x) upon the catalytic activity was verified. The Ca_1-xK_xTiCu_x/2O₃ sample with x = 0.3 showed the highest activity with a yield up to 89 % to produce fatty acid ethyl esters (FAEE’s) after 24 h reaction using 15 wt.% catalysts, 120 °C and 40 bars. The enhancement in the activity was ascribed to the substitution of the Ca⁺²sites by K⁺ and Ti⁺⁴ by Cu⁺² and to the hollow morphology favoring a more effective interaction between the soybean oil and the active basic sites of the catalysts.