Catalytic hydrogenation of cyclohexene 4. The effect of sulfur on supported platinum
1981; Elsevier BV; Volume: 71; Issue: 1 Linguagem: Inglês
10.1016/0021-9517(81)90208-6
ISSN1090-2694
Autores Tópico(s)Catalysis for Biomass Conversion
ResumoThe rate of turnover rt for the gas-phase hydrogenation of cyclohexene on platinum catalysts in the absence or the presence of sulfur was measured at 273 K and pressures of H2 and C6H10 equal to 9.31 and 2.66 kPa. If the number of platinum sites is measured by means of hydrogen chemisorption, rt is found to be the same for all catalysts and equal to 0.65 s−1 if it is assumed that one site corresponds to one hydrogen adatom. By contrast, if the number of platinum sites is measured by means of oxygen chemisorption or dihydrogen titration of prechemisorbed oxygen, rt is constant only for the catalysts which are not contaminated by sulfur. For the others, values of rt scatter depending on the amount of sulfur on platinum. It appears that adsorbed sulfur takes up oxygen, thus leading to excess values of the number of platinum sites. The constancy of rt measured by hydrogen chemisorption on platinum with or without sulfur confirms the structure insensitivity of cyclohexene hydrogenation on that metal and the adequacy of hydrogen chemisorption as a method of counting platinum sites.
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