Catalysts based on Ru/mesoporous phosphate heterostructures (PPH) for hydrotreating of aromatic hydrocarbons

Mesoporous phosphate heterostructure (PPH) materials have been used as supports of ruthenium catalysts with a 5 wt.% metal content. A pristine support (SiPPH) was used, consisting of expanded zirconium phosphate with silica galleries and a potassium exchanged material (denoted as KSiPPH) which was prepared by the cationic exchange of the pristine support to reduce its original acidity by 20%. Ruthenium supported on both SiPPH and KSiPPH was obtained by incipient wetness impregnation using an aqueous solution of ruthenium(III) chloride and reduction at 400 °C without previous calcination. These catalysts were assayed in the hydrogenation and hydrogenolysis/hydrocracking of tetralin at different temperatures. They show a similar catalytic performance although the 5Ru-SiPPH catalyst displays better activity at 350 °C, giving 95% conversion in the steady-state and a very good balance between yields of hydrogenation (55%) and hydrogenolyis/hydrocracking products (28%). This better performance could be due to its better metallic properties and greater acidity. In addition, the performance of the best catalyst was studied for thiotolerance with a feed containing dibenzothiophene (DBT), a sulphur containing molecule, at concentrations of 300 and 600 ppm. This catalyst shows an excellent performance with 300 ppm of DBT after 6 h on-stream. The catalysts were characterized by several instrumental techniques such as X-ray diffraction (XRD), adsorption–desorption of nitrogen, temperature-programmed desorption (TPD) of NH3, X-ray photoelectron spectroscopy (XPS), TEM and H2 and O2-chemisorption.

Graphical abstractThe use of acid mesoporous phosphate heterostructure (PPH) materials as supports of ruthenium catalysts prepared by the incipient wetness impregnation, with a metal content of 5 wt.%, provides active and stable catalysts for the hydrogenation and hydrogenolysis/hydrocracking of tetralin under high hydrogen pressures. Figure optionsDownload full-size imageDownload as PowerPoint slide