Effect of Acid Properties of Fluorinated Beta and ZSM-5 Zeolites Used as Supports of Ni Catalysts for the Catalytic Hydrodeoxygenation of Guaiacol

Identifier:  imarina:9386603

Handle: https://hdl.handle.net/20.500.11797/imarina9386603

Authors:  Quintero-Arroyo, Gabriela; Rueda, Angie C; Granados-Reyes, Judith; Fals, Jayson; Cesteros, Yolanda

Abstract:
Commercial NH4-Beta and Na-ZSM-5 zeolites were fluorinated with different amounts of NH4F and using different procedures (room temperature, conventional refluxing, microwave refluxing). Samples were characterized by XRD, N2 physisorption, FTIR, 1H NMR, SEM-EDS, and TGA of adsorbed cyclohexylamine. An increase in the concentration of NH4F led to fluorinated zeolites with higher surface areas and slightly lower amounts of Br & oslash;nsted acid sites due to some dealumination. Fluorination by conventional or microwave refluxing at shorter times did not dealuminate ZSM-5, resulting in the formation of higher particle sizes. Ni/fluorinated beta catalysts were more active than Ni/fluorinated ZSM-5 catalysts for the hydrodeoxygenation of guaiacol at 180 degrees C and 15 bar of H2 for 1 h due to their higher amount of acid sites. The appropriate proportion of metallic and Br & oslash;nsted acid centers allowed for the selective obtention of cyclohexane (58%) for the Ni supported on beta fluorinated with NH4F 0.1 M catalyst. The combination of this fluorinated beta to a Ni/ordered mesoporous carbon catalyst significantly boosted its selectivity to cyclohexane from 0 to 65%. Fluorinated ZSM-5 samples, although having stronger Br & oslash;nsted acid sites, as observed by 1H NMR, they had lower amounts, leading to higher selectivity to cyclohexanol when used as catalytic supports.