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The role of transition metal sulfides in hydrotreatment. III. Acidity, XPS and catalytic activity

1987; Elsevier BV; Volume: 31; Issue: 1 Linguagem: Inglês

10.1016/s0166-9834(00)80662-4

1873-3867

M.M. Ramı́rez de Agudelo, Leonardo González–Reyes, N. Do Campo,

Metal Extraction and Bioleaching

Although, recently, most of the research on catalysis has been devoted to hydrotreatment, attention has been paid to hydrodesulfurization (HDS) but very little has been done on hydrodemetallization (HDM). This article is part of a systematic study directed towards defining the role of transition metal sulfides in hydrotreatment reactions [1,2]. We have considered catalysts supported on silica or alumina. Acidity has been evaluated using pyridine as probe molecule. This property can be attributed to the sulfide phase of the catalysts. The alumina supported catalysts were more acid than the silica supported catalysts. Since the acidity might exclusively be of Lewis type, the pattern observed through the first row transition metal sulfides reflects the trend of the electron-aceptor character of these sulfides. The XPS results indicate that catalysts are partially sulfided (at 400°C). At the same time, the results corroborate a better Me-support interaction on alumina than on silica. The HDM and HDS intrinsic activities, using a desalphalted (DAO) Morichal as feed were evaluated normalizing conversion in terms of the surface metal sites per surface area. The intrinsic activity patterns obtained for the first row transition metal sulfides, were very similar to those mentioned of acidity, reaffirming the importance of the electronic structure of the sulfide phase on its catalytic activity.