Preparation and characterization of 5%Ni/γ-Al2o3 catalysts by complexation with NH3 derivatives active in methane steam reforming

Abstract 5 wt%NiO/γ-Al 2 O 3 supported nickel catalysts were prepared by incipient wetness impregnation (IWI) method. Ammonia (NH 3 ) derivatives aliphatic amines based on: ethylamine (EA), diethylamine (DEA) and triethylamine (TEA) were used as ligands to complex Ni(NO 3 ) 2, 6H 2 O nickel nitrates salts. Various techniques including: Thermogravimetric (TGA)- Differential thermal analysis DTA, XRF, SEM, XRD, RTP and BET were used to characterize the physic-chemical properties of the mentioned catalysts. The catalytic performances were evaluated in steam methane reforming reaction at different temperatures ranging from 500 to 800 °C. According to the results, Ni 2+ ions form strongly different complexes with NH 3 , EA, DEA and TEA amines. Based on DRX and TPR measurements, the relative stronger encumbrance due to the bigger aliphatic amines volume of the corresponding intermediate complexes avoids the growing of NiAl 2 O 4 spinel phase and leads to a sensitive decrease of the average NiO crystallites size from 15 to 9 nm appearing in high dispersion state and strongly interacting with the support with Strong Metal Support Interaction (SMSI). High catalytic performances are achieved with Ni-Diethylamine and Ni-Triethylamine catalysts at 700 °C in steam reforming reaction (CH 4 conversion = 99%, H 2 yield = 82%) under GHSV 24 × 10 3  mL g cat −1 .h −1 and H 2 O/CH 4  = 3.