A. Tahri et al., THERMODESORPTIONS AND THERMOREACTIONS WIT H HYDROGEN OF CARBON-MONOXIDE AFTER ITS CHEMISORPTION ON A NICKEL-CATALYST .1. MECHANISM OF THE METHANATION, Journal de chimie physique et de physico-chimie biologique, 92(1), 1995, pp. 173-187
After chemisorption of CO at room temperature on silica-supported Ni,
the spectrum of TPSR (Temperature Programmed Surface Reaction) with H-
2 is very similar to that obtained after chemisorption of CO2. In part
icular the CH4 and H2O peaks are obtained simultaneously. The same sur
face heterogeneity as already evidenced by the TPD (Temperature Progra
mmed Desorption) spectra of CO2 is also evidenced by the TPD spectra o
f CO. However the latter show that supplementary CO adspecies, less ti
ghtly bonded, are formed during CO adsorption as compared to the CO2 c
ase. Only a part of the CO is reversibly chemisorbed, most of it being
subjected during heating to disproportionation or dissociation with r
e-association and desorption at T > 400 degrees C. It is the irreversi
bly chemisorbed CO which is involved in the methanation reaction. The
latter proceeds quickly after H-assisted breaking of the C-O bond.