Search

Abstract: The deoxygenation of rapeseed oil has been studied over sulfided NiMo-alumina catalysts (NiMoS-alumina). The main focus has been on the preparation of catalyst precursors (oxide form of sulfided NiMo-alumina catalysts – NiMoO-alumina) with a different distribution of Ni species in order to contribute to the understanding of the effect of catalyst preparation on the activity/selectivity of NiMoS-alumina catalysts in the deoxygenation of rapeseed oil. To analyze the state of Ni species the NiMoO-alumina catalysts have been characterized by UV–vis diffuse reflectance spectrometry (DRS), X-ray diffraction (XRD) and XPS. It has been found out that the NiMoO-alumina catalysts with higher population of octahedral nickel species resulted in more active NiMoS-alumina catalysts than those containing higher population of tetrahedral nickel species. [Copyright &y& Elsevier]

Abstract: A series of supported Ni/γ-Al2O3 samples were prepared and then used to identify the surface Ni species. The samples were characterized by ICP-AES, XRD, TPR, and XPS. The results indicated that two types of Ni species occurred on the samples with Ni loading<9.1wt%, while four types of Ni species occurred on the samples with Ni loading>9.1wt%. The reduction temperatures around 350, 500–520, 620–650, and 750–800°C corresponding to Ni species were related to amorphous NiO, crystal NiO, NiAl2O4, and NiAl x O y (x >2), respectively. A correlation was made between the catalytic activities and the surface Ni species. For the catalysts that were difficult to reduce (Ni loading<9.1wt%), the activities were very poor at low reduction temperatures; for the easily reducible catalysts (Ni loading>9.1wt%), the activities were excellent in a wider reduction temperature range from 400 to 800°C. [Copyright &y& Elsevier]