Effects of steam addition on the spontaneous activation in Ni3Al foil catalysts during methanol decomposition

Methanol decomposition was carried out under steam addition (steam-to-carbon ratio (S/C) = 0–2.0) over cold-rolled Ni3Al foils at temperatures ranging from 513 to 793 K. The spontaneous activation was clearly observed at S/C = 0.1 and below, while suppressed at S/C = 0.5 and above. Surface characterization of the spent foils revealed that fine Ni particles were formed at S/C = 0.1 and below due to the selective oxidation/hydroxylation of Al, while further steam addition suppressed it due to the oxidation/hydroxylation of both Al and Ni. The results confirm the spontaneous activation mechanism due to the formation of fine Ni particles which is induced by the selective oxidation/hydroxylation of Al. Reaction analysis revealed that methanol decomposition mainly occurred even under steam addition. It also revealed the effect of steam addition on the minor side reactions, methanation, water-gas shift reaction and carbon deposition.

Steam addition was found to suppress the spontaneous activation which was characteristically observed in methanol decomposition over our newly discovered Ni3Al foil catalysts. The results were related to the important role of selective oxidation/hydroxylation of Al in the spontaneous activation.Figure optionsDownload as PowerPoint slide