Abstract :
[en] Nickel supported gamma alumina catalysts have been developed for the use in glycerol reforming applications. The catalysts were developed using the sol-gel method and characterized using TPR, BET, XRD, TEM, and ICP techniques. The catalysts were prepared with different precursors; two nickel precursors: nickel acetate (Ni(CH COO) .2H O) and nickel nitrate (Ni(NO ) .6H O), two different alumina precursors: aluminum tri-sec-butoxide (C H AlO ) and aluminum isopropoxide Al(O-iC H ) , two funtionalized silicon precursors: EDAS ((CH O) Si(CH ) NHCH CH NH ) and AMS (H N(CH ) Si(OCH ) ), and two different solvents: 2-methoxyethanol (CH OCH CH OH) and 2 ethoxyethanol (C H OCH CH OH) in order to determine the texture, morphology and crystallographic properties of each catalysis and select the best preparation route. Only the formation of γ-Al O is aimed in order to use these alumina materials catalytic supports because of it present high specific surface area and pore volume values. So it was developed a synthesis sol-gel procedure for the cogelation between the funtionalized silicon precursors and alumina precursors. For this purpose, a certain weight percent of Ni salt was added to a solvent and a silicon precursor with continuous stirring. Then, a certain amount of alumina precursor and additionally another solution of solvent and water were added. The sample was dried at 80 °C and atmospheric pressure for 3 days, after that, using a controlled ramp, the pressure decreased to 10 mbar for 3 days and the temperature was increased to 150 °C. The samples were calcined at two different temperatures (550°C and 900°C) for 8 h. Finally, the catalysts were reduced at reduction temperature of 350°C for approximately 2-3 h. Hydrogen was utilized as a reducing gas at a flow rate of 60 mL/min. From the results obtained, it was observed that the catalysts prepared with nickel acetate, 2-methoxyethanol and EDAS present a great stability in their structure, the presence of γ-Al2O3 was confirmed by XRD analysis, Ni metal particles doped in gamma alumina were noted using TEM analysis. The calculation of the crystal size using the Scherrer equation determined average particle sizes between 8-40 nm depending on the Ni concentration of the catalyst. According to the BET analysis, it was determined that samples present TYPE I & II isotherms, and microporous & mesoporous solids depending on the Ni concentration. The catalysts presented a BET surface area between 250-515 m /g and average pore size between 2 to 7 nm.
