Catalytic hydrotreating of heavy vacuum gas oil on Al- and Ti-pillared clays prepared by conventional and microwave irradiation methods

Alternate microwave irradiation methods were used for preparing Al- and Ti-pillared clays from the natural swelling montmorillonite of Durango (Mexico) and precursor salts (AlCl3 and TiCl4). Their properties were compared with Al- and Ti-PILCS (pillared interlayered clays) prepared by conventional methods. The solids treated with microwave radiation have a stacking order with d(0 0 1) of 18.8 Angstrom for Al-PILCS and a distribution of do() I values between 14 and 22 A for Ti-PILCS. In contrast, the conventional materials show similar interplanar spacings (d(0 0 1)) for Al-PILCS but a delaminated structure is always obtained for Ti-PILCS after calcining in air at 400 degreesC. The surface areas (BET) of the pillared clays varied between 200 and 360 m(2)/g, The pyridine-FTIR spectra of both series indicated mostly the presence of Lewis acid sites, up to 400 mumol Py/g. Atomic absorption spectroscopy indicated a significant variation of the Si/Al ratio for Ti-PILCS, caused by partial dealumination. Co-Mo/PILCS catalysts prepared by microwave methods were compared against CoMo/gamma-Al2O3 (industrial catalysts) in the HDS of heavy vacuum gas oil derived from Maya crude (sulfur content: 2.21 wt.%). The Co-Mo/Al-PILCS from microwave radiation methods had the highest surface area (BET), i.e. 358 m(2)/g, and was more active with respect to the reference catalysts under the specific conditions used (32.6% versus 29.8% HDS/g(cat)). (C) 2002 Published by Elsevier Science Inc.