Adsorption of hydrocarbons on nickel catalysts as studied by magnetic methods, and application to the study of hydrogenolysis and D2 ‐ hydrocarbon exchange reactions

The decrease of saturation magnetization of nickel upon hydrocarbon adsorption gives information on the nature of chemisorbed species. It is shown that a low coverages and moderate temperature (300K), hydrocarbon molecules undergo a substantial dehydrogenation; for higher temperature (400K) molecules are completely dehydrogenated and cracked according to magnified image The adsorbed species involve a large number of Ni atoms. Hydrocarbon adsorptions are inhibited by addition of Cu atoms (alloying) or by preadsorbed hydrogen, and this is interpreted in both cases in terms of dilution effect of the active phase (Ni) by Cu or H atoms. Consequences on hydrogenolysis and exchange reactions are examined, and comparison between predicted characteristics and experimental data are presented in the case of ethane, propane, butane hydrogenolysis over Ni and Ni ‐ Cu catalysts, and deuterium‐methane and ethane exchange over Ni catalysts.