Catalytic Features of Mg Modified Ni/SiO2/Silica Cloth Systems in the Decomposition of Methane for Making “CO x -Free” H2.

The influence of the Mg addition on the catalytic performance of a 20% Ni based SiO₂/silica cloth system in the decomposition of methane for making “CO _x -free” H₂ in the T_R range 773–873 K has been evaluated. As the Mg_at/Ni_at ratio increases from 0.10 to 2.20 the incipient Ni–Mg-O interaction becomes stronger until the formation of Ni _x Mg_{(1− x)}O solid solution. The presence of Mg²⁺ ions allows a higher carbon capacity (C/Ni, number of CH₄ molecules converted per Ni atom until complete catalyst deactivation) and consequently a higher H₂ productivity of the Ni based systems which results in a smoothing effect of the unavoidable declining activity trend even if it does not affect the tip growth coking mechanism. [ABSTRACT FROM AUTHOR]