Conversion of guaiacol over supported ReOx catalysts: Support and metal loading effect

Abstract In the present work, the catalytic activity and selectivity for the conversion of 2-methoxyphenol over ReOx catalysts supported on SiO 2 , Al 2 O 3 and SiO 2 -Al 2 O 3 in a batch reactor at 300 °C and 5 MPa of hydrogen pressure were studied. Additionally, several SiO 2 -supported ReOx catalysts were synthesized with different metal loadings. These catalysts were characterized by N 2 adsorption, X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (TPR), temperature-programmed desorption of ammonia (TPD-NH 3 ), Raman spectroscopy and ultraviolet visible (UV–vis-DR) spectroscopy. ReOx catalyst supported over SiO 2 revealed the highest catalytic activity and selectivity towards deoxygenated products. This was attributed to a higher formation of oxygen vacancies (active sites) on SiO 2 , due to a weaker metal-support interaction. The increase of Re content on SiO 2 resulted in an increase of guaiacol conversion, reaching a maximum at about 1.8 atoms of Re per nm 2 of support. The decrease of activity over 1.8 atoms of Re per nm 2 of support was correlated to loss of active site due to the formation of aggregates of ReOx.