Anisole hydrodeoxygenation over Ni-Cu bimetallic catalysts: The effect of Ni/Cu ratio on selectivity

The activity and selectivity of model NiCu-SiO2 catalysts with the high metal loading (90%) and various Ni content was studied in anisole hydrotreatment at 280 degrees C and a hydrogen pressure of 6 MPa in a batch reactor. To obtain the alloys with the homogeneous phase composition, the catalysts were prepared by simultaneous decomposition of metal salts with the subsequent stabilization with 10 wt% SiO2. The composition of the NiyCu1-y alloy surface was estimated from the combination of XPS and XRD data. On the basis of obtained kinetic data, a reaction scheme of anisole conversion was proposed. The scheme includes two parallel routes, one of which leads to C-ar-O bond cleavage with the formation of benzene, which is then converted to cyclohexane (HDO route), while the second route leads to hydrogenation of the aromatic ring of anisole with the formation of methoxycyclohexane and cyclohexanol (HYD route). The experimental dependence of anisole conversion was described by the first-order kinetics with respect to the reagents. The effect of the surface composition of the active phase NiyCu1-y on the specific catalytic activity was examined. According to the proposed reaction scheme, the dependence of the first-order rate constants for both routes on the nickel content in the active component of the catalysts was determined. The selectivities of both reaction routes of anisole conversion (HDO and HYD) were found to be independent of the Ni content except for the nickel-rich and copper-rich sides. The specific catalytic activity in the HDO route rises with an increase in the nickel content in the whole range of Ni loading. (C) 2013 Elsevier B.V. All rights reserved.