Characterization and catalytic activity of Ni-W/SiO_2-Al_2O_3 hydrocracking catalysts

摘要

Characterization of Ni-W SiO_2-AlO_2 catalysts was carried out by microcalorimetry, TPR and oxygen chemisorption. The effect of incorporation of individual metals and their sequence of addition to the support on the properties and catalytic activity for cyclohexene hydrogenation and cumene cracking was investigated. While the addition of nickel to SiO_2-Al_2O_3 has little effect on the acidity, tungsten has generated some new strong acid sites, which do not seem to have beneficial effect for cumene cracking. Low temperature TPR peak in the bimetallic catalysts falls around 760 K due to Ni-W species while the high temperature peak around 1115-1223K corresponds to W species. W/SiO_2-Al_2O_3 has a lower oxygen chemisorption than its nickel counterpart but has a higher hydrogenation rate. Tungsten is the activty metal for hydrogenation. W/Ni/SiO_2-Al_2O_3 catalyst has better hydrogenation and cracking activity.