Towards triglycerides-based biorefineries: Hydrolysis-reforming-hydrogenation in one-pot over Ni/γ-Al2O3 based catalysts

The main objective of this study is to assess the efficiency of Ni/gamma-Al2O3 calcined at different temperatures and Ni-Sn/gamma-Al2O3 with different Ni:Sn atomic ratios catalysts for hydrolysis-reforming-hydrogenation reactions in a one-pot of the soybean oil. Ni/gamma-Al2O3 catalysts were prepared by incipient wetness impregnation, further dried at 110 degrees C and calcined. Ni-Sn/gamma-Al2O3 catalysts were prepared by using the same steps of the monometallic ones and calcined at 300 degrees C. The catalysts were characterized by N-2-isotherms, XRF, XRD, TPR, DRS-UV-vis, and H-2-TPD. Before the reaction, the catalysts were reduced under H-2 at 550 degrees C. gamma-Al2O3 was the best catalyst for the hydrolysis reaction that enabled the complete conversion of triglycerides to glycerol and the respective formation of soybean oil fatty acids. Ni/gamma-Al2O3 calcined at 300 degrees C, which had the highest metallic surface area after reduction, was the best monometallic catalyst for stearic acid production. The addition of tin has improved the hydrolysis reaction and the glycerol aqueous-phase reforming, enhancing in-situ H-2 production and, consequently, the selectivity towards saturated fatty acids. The beneficial effect afforded by Sn may be due to the presence of Sn at defective Ni sites or by the formation of a Ni-Sn (Ni3Sn) alloy. The results indicate that a triglyceride-based biorefinery approach, in which glycerides, glycerol, hydrogen, saturated and unsaturated fatty acids c be tuned in by catalysts and reaction conditions.

Automated summary

The study assessed the efficiency of Ni/gamma-Al2O3 and Ni-Sn/gamma-Al2O3 catalysts for hydrolysis-reforming-hydrogenation reactions in soybean oil, showing that gamma-Al2O3 was the best catalyst for hydrolysis and Ni/gamma-Al2O3 calcined at 300 degrees C was the best monometallic catalyst for stearic acid production. The addition of tin improved the reactions by enhancing H-2 production and selectivity towards saturated fatty acids.