The methanation of carbon monoxide with Pt/ZnO catalysts activated at three different temperatures (220, 250, 300°C) is reported. An increase in specific activity that is paralleled by a drop in the CO chemisorption ability is found when the activation temperature is increased. Characterization of the samples with IR and TEM indicates extensive formation of a PtZn alloy already at 220°C. As the activation temperature increases, the spectroscopic data indicate an increased back-donation in the CO antibonding orbitals which seems to be related to a significant ligand effect of Zn in the alloy. It is suggested that other cooperating effects like the stabilization of the intermediate products and a larger hydrogen supply from the alloy during the reaction may play a significant role in the CO methanation. © 1990.
Pt/ZnO catalysts: Spectroscopic and catalytic evidences of a ligand effect as a consequence of PtZn alloying
PINNA, Francesco;STRUKUL, Giorgio;
1990-01-01
Abstract
The methanation of carbon monoxide with Pt/ZnO catalysts activated at three different temperatures (220, 250, 300°C) is reported. An increase in specific activity that is paralleled by a drop in the CO chemisorption ability is found when the activation temperature is increased. Characterization of the samples with IR and TEM indicates extensive formation of a PtZn alloy already at 220°C. As the activation temperature increases, the spectroscopic data indicate an increased back-donation in the CO antibonding orbitals which seems to be related to a significant ligand effect of Zn in the alloy. It is suggested that other cooperating effects like the stabilization of the intermediate products and a larger hydrogen supply from the alloy during the reaction may play a significant role in the CO methanation. © 1990.
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