Influence of calcination on metallic dispersion and support interactions for NiRu/TiO2 catalyst in the hydrodeoxygenation of phenol

Abstract

Bio-oil upgrading by hydrotreatment has been considered as a renewable route for fuels production and potential substitutes for fossil oil distillates. Traditional hydrodesulfurization catalysts (sulfided CoMo and NiMo) used in petroleum refining have been evaluated in hydrodeoxygenation reactions with high selectivity to aromatics. However, significant deactivation has been commonly observed, due to the low sulfur content in bio-oil. Thus, the development of different active and stable catalytic materials is needed. In this regard, we have previously reported a synergetic effect between Ni and Ru bimetallic materials supported on Al2O3, TiO2 and ZrO2 in phenol HDO with promising activity and selectivity results. In particular, materials supported TiO2 on displayed the highest activities. Therefore, the aim of this work was to evaluate the effect of calcination on dispersion and metal-support interactions and their impact on activity and selectivity for NiRu/TiO2 catalysts in HDO of phenol as a model compound for bio oil. Catalysts were characterized by hydrogen chemisorption, Temperature- programmed reduction, X-ray photoelectron spectroscopy, High resolution electron microscopy. Additionally, hydrogenation of benzene was used as a structure unsensitive reaction in order to obtain more information about metallic dispersion. A highly active NiRu catalyst was obtained when calcination was avoided prior to reduction. The calcination procedure induced the formation of metallic oxides and it provoked less dispersed NiRu species as compared with catalysts without this previous treatment. On the contrary, the formation of metallic species from direct reduction of precursor salts contributed to produce highly dispersed species.