Carbon dioxide reforming of methane over 5 wt% nickel calcium aluminate catalysts - effect of preparation method

The effect of the preparation method on the catalytic properties and performance of 5 wt.% Ni on calcium aluminate (molar CaO/Al2O3=1/2) in the reaction of CO2 reforming of CH4 was investigated. The techniques employed for the preparation were the incipient wetness and total blending. The catalyst sample prepared by the deposition of Ni on already formed calcium aluminate proved to be more active with lower coke deposition for the reaction of reforming than the samples prepared by the total blending technique where the nickel compound was premixed with Ca and Al compounds. The differences in activity were attributed to different amounts of active NiO on the surface of the prepared samples as it was proved from XPS spectra and H-2-TPD profiles. Specific desorption peaks, which appeared in TPD profiles of catalysts prepared by total blending technique and calcined at 700 degrees C and 900 degrees C, were associated with hydrogen spillover to the support. Furthermore, long term testing of the catalyst prepared by the incipient wetness technique showed no loss of activity with low coke deposition. TPO experiments conducted using (CH4)-C-13/CO2/He mixture demonstrated that the adsorbed carbon species are formed via the CH? and CO2 molecular routes. (C) 1998 Elsevier Science B.V. All rights reserved.