Thioresistant PdPt/Al/SBA-15 for Naphthalene Hydrogenation
José Escobar, J.A. Colín-Luna, María C. Barrera
Abstract
Al-modified (chemical grafting) SBA-15 (SiO 2 /Al 2 O 3 = 5 mass ratio) materials were used as noble metal (NM, monometallic Pt or Pd and bimetallic Pd/Pt = 4, 0.5 wt % loading) carriers. The materials were studied by XRF, N 2 physisorption, XRD, TPR, pyridine thermodesorption FTIR, and STEM (HAADF). Hydrogenating properties were tested in naphthalene ( N ) conversion; meanwhile, dibenzothiophene (80 ppm) was added in some experiments to evaluate the thioresistance of prepared catalysts. Al-incorporation provided enhanced Lewis and Brønsted acidity to pristine SBA-15 due to alumina-like domains that contributed to Pt dispersion reflected in augmented hydrogenation. The Pt-based catalyst was the most active in N saturation ( T = 290 °C, P = 6.97 MPa), whereas the Pd/Pt (4/1) formulation had enhanced thioresistance probably due to NM alloying (electron transfer in Pt-Pd core–shell particles) in conjunction with weak Brønsted acidity (Si–O–Al bonds, electron transfer from NM) that provided additional sites for aromatic adsorption. Enhanced thioresistance is crucial for aromatic saturation of NM catalysts aimed at second-stage polishing of ultralow S diesel.