Enrique Rodríguez-Castellón

Effects of preparation method and sulfur poisoning on the hydrogenation and ring opening of tetralin on NiW/zirconium-doped mesoporous silica catalysts

Nickel-tungsten supported on zirconium-doped mesoporous silica catalysts was prepared by using different methodologies and successfully tested at the hydrogenation and ring opening of tetralin. The preparation method has an important influence on surface properties such as dispersion, location, and reducibility of NiW species as deduced from H2-TPR, H2 chemisorption, FTIR spectra of CO adsorbed, and XPS studies. Thus, when nickel, in the form of nickel citrate, is first incorporated followed by tungsten, a catalyst is obtained with the highest acidity and the best catalytic performance, yielding a full conversion of tetralin (100%) as well as high yields of hydrogenation (42.7%) and ring-opening (56.1%) products under mild conditions (6.0 MPa of H2 and 375 ◦ C). This catalyst exhibits a good thiotolerance in the presence of 300 ppm of dibenzothiophene in the feed, maintaining a high catalytic activity in the hydrogenation and ring-opening reactions after 6 h

Influence of the metallic precursor in the hydrogenation of tetralin over Pd–Pt supported zirconium doped mesoporous silica

Palladium–platinum supported on zirconium doped mesoporous silica catalysts have been prepared by incipient wetness impregnation with two different precursors: (i) a dinuclear precursor [PdPtCl2(μ-dppm)2] where dppm = Ph2PCH2PPh2; and (ii) PdCl2 and H2PtCl6·6H2O. The catalysts obtained with the bimetallic precursor show a much smaller metallic particle size than those prepared using monometallic precursors. The influence of the precursor in the hydrogenation of tetralin at high hydrogen pressure was studied. Both types of catalysts exhibit a good hydrogenation activity with a poor hydrogenolysis/ring opening activity. The type of precursor has a marked influence in the observed trans- to cis-decalin ratio being higher for catalysts prepared with monometallic precursors. Both types of catalysts show a good thiotolerance against dibenzothiophene, but the observed poisoning is more reversible in the case of catalysts prepared using monometallic precursors. A positive effect of the hydrogen pressure over the catalyst thiotolerance was observed, and using a P(H2) of 6 MPa, the catalyst with a 2 wt% PdPt prepared from monometallic salts was found to be very resistant to sulfur poisoning, with a tetralin conversion higher than 95% in the presence of 1375 ppm of DBT in the feed, at 588 K.