Mesoporous silica–alumina modified by acid leaching as support of Pt catalysts in HDS of model compounds

The potential of mesoporous silica–alumina (MSA) modified by acid leaching as alternative support for Pt catalysts was studied in hydrodesulfurization (HDS) of thiophene and benzothiophene. The supports were characterized by N2 adsorption, XRD, 27AL MAS NMR, electron microscopy (SEM, HRTEM) and by activities in cyclohexene isomerization and cumene cracking. The composition of the catalysts and Pt dispersion were determined by ICP and H2 or CO sorption, respectively. Progressive leaching of the parent MSA from 50% Al2O3 to 11% Al2O3 content led to increase of the BET surface area and exposition of strong acidity. This positively affected the activities of the reduced Pt catalysts in thiophene HDS. Deposition of 1.5 wt.% Pt on MSA (11% Al2O3) by using Pt(NH3)4(OH)2 as precursor gave the best catalyst, several times more active in thiophene HDS than the weight equivalents of sulfided CoMo/Al2O3 or reduced Pt/HY zeolite. In benzothiophene reaction, its activity was slightly above that of CoMo/Al2O3 and about twofold compared to Pt/HY.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Leaching of non-acidic Al2O3 from mesoporous silica–alumina carrier (50% Al2O3) by HNO3 increased the BET area, proportion of AlTET and exposed strong acidity. ▶ This improved the HDS activity of Pt catalysts prepared from such modified carriers. ▶ The best catalyst with 1.5% Pt was much more active in HDS of thiophene and benzothiophene than Pt/HY and industrial CoMo/Al2O3.