Isomerization of n-hexane over silica-supported heteropoly acids promoted by the reduced Ce-Ni oxides

The structure and catalytic properties of silica-supported heteropoly acids promoted by the reduced Ce-Ni oxides are first studied by using chemical analysis XRD, FT Raman, XPS, EPR, TG, surface area measurements, and microreactor test. It is found that silica-supported heteropoly acids have isomerization activity, but are very easy to deactivate by coke deposition. With the promotion of the reduced Ce-Ni oxides, however, the better activity and the higher selectivity to isomers could be obtained, suggesting that the reduced Ce-Ni oxides really have hydrogenating/dehydrogenating functions. Moreover, it is found that the presence of the reduced Ce-Ni oxides is not only beneficial for eliminating the coke deposition, but also effective for maintaining the structure of silica-supported heteropoly acids during reaction. The effect of the composition of the mechanical mixtures of silica-supported heteropoly acids and the Ce-Ni oxides on the catalytic properties has been explored. (C) 2002 Elsevier Science (USA)