Characterisation of thermal properties of oxide, reduced and sulphided forms of alumina supported Co(Ni)-Mo(W) catalysts prepared by co-precipitation

This study deals with alumina supported Co(Ni)-Mo(W) catalysts prepared in one step by the co-precipitation method. Results of temperature-programmed reduction (TPR) of oxide forms of the catalysts, and differential thermal a nalysis (DTA) and thermal gravimetry (TG) of the oxide, reduced and simulta neously reduced and sulphided forms of the catalysts are presented. Reducti on of the catalysts has been found to begin already at about 150 degreesC. It has been established that at 400 degreesC the CoMo catalyst practically does not reveal any mass loss after 30 min reduction with hydrogen, while t he NiMo catalyst shows a large mass loss after 60 min reduction, continuing with time. The catalyst NiW also shows a significant mass loss already aft er 10 min reduction with hydrogen, and this mass loss continues to occur as the time of reduction increases. (C) 2001 Elsevier Science BN. All rights reserved.