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 SiO2, Al2O3 and SiO2-Al2O3 in a batch reactor at 300 °C and 5 MPa of hydrogen pressure were studied. Additionally, several SiO2-supported ReOx catalysts were synthesized with different metal loadings. These catalysts were characterized by N2 adsorption, X-ray photoelectron spectroscopy (XPS), temperature programmed reduction (TPR), temperature-programmed desorption of ammonia (TPD-NH3), Raman spectroscopy and ultraviolet visible (UV–vis-DR) spectroscopy. ReOx catalyst supported over SiO2 revealed the highest catalytic activity and selectivity towards deoxygenated products. This was attributed to a higher formation of oxygen vacancies (active sites) on SiO2, due to a weaker metal-support interaction. The increase of Re content on SiO2 resulted in an increase of guaiacol conversion, reaching a maximum at about 1.8 atoms of Re per nm2 of support. The decrease of activity over 1.8 atoms of Re per nm2of support was correlated to loss of active site due to the formation of aggregates of ReOx.