Various characteristics of Ni and Pt–Al 2O 3 nanocatalysts prepared by microwave method to be applied in some petrochemical processes

摘要

Alumina-supported metal nanocatalysts were prepared via the microwave method, by loading nano Ni particles (at 1, 3 and 5wt%) or nano Pt particles (at 0.3, 0.6 and 0.9wt%). Structural and adsorption features of the nano catalysts were revealed through XRD, DSC-DTA, TEM, H2-chemisorption and N2-physisorption. N2-adsorption–desorption isotherms of type IV were related typically to mesoporous materials with H2class of hysteresis loops characterizing ink bottle type of pores. The well dispersed nano-sized metal particles were evidenced in the studied catalytic systems, exhibiting marked thermal stability up to 800°C. The catalytic performances of different catalyst samples were assessed during cyclohexane, normal hexane and ethanol conversions, using the micro-catalytic pulse technique at different operating conditions. The 5% Ni–γ–Al2O3sample was found to be the most active in dehydration of ethanol to produce ethylene, as well as inn-hexane cracking. However, the 1% Ni–Al2O3sample showed the highest dehydrogenation activity for selective production of benzene from cyclohexane. On the other hand, the 0.9% Pt–γ–Al2O3sample exhibited the highest activity in the dehydration of ethanol and in the dehydrogenation of cyclohexane. The 0.3% Pt–γ–Al2O3sample was the most active in the dehydrocyclization of normal hexane, as compared to the other catalyst samples under study.