Inclusion of Molybdenum into microporous and mesoporous materials

Transition metal supported catalysts have important value in industry and their developments continue to attract interest in research. Considering the importance of metal and metal oxide supported catalysts, this study focused on the development of molybdenum and molybdenum oxide supported catalysts, using porous supports. The supports were zeolite Y types, large microporous cloverite, and mesoporous MCM-41. The large pore supports were used to produce catalysts that can accommodate catalysis reactions involving large molecules. The objective of this work is to study the preparation and characterisation of the molybdenum supported catalysts. Zeolite Y was used in the forms of NaY, CoY, CuY and GaY, with the latter three obtained through ion exchange of NaY. The syntheses of cloverite and MCM-41 were parts of the study. The main preparation method used to introduce molybdenum was metal organic chemical vapour deposition (MOCVD) of Mo(CO)6, and was applied to all supports. Incorporation of molybdenum into MCM-41 was also conducted through an inclusion into the synthesis mixture, impregnation, grafting, and solid state ion exchange. Catalyst characterisation was performed by various techniques, including XRD, gravimetry, FTIR, Raman and XAS. Results show that MOCVD of Mo(CO)6 works best in Y zeolites in term of the amount of molybdenum retained after decomposition. The effect of different cations present on Y zeolite was not significant to the amount adsorbed and to the interaction between precursor and the supports, except for gallium that caused a lower adsorption. Cloverite synthesis pointed out that using piperidine as template produced cloverite that can retain more molybdenum compared to quinuclidine templated cloverite. The overall amount retained was lower than the amount retained in Y zeolites, although the cloverite pore size is larger than Y zeolite's, indicating a poorer interaction between cloverite and the molybdenum precursor Mo(CO)6. The inclusion of molybdenum into MCM-41 either by MOCVD of Mo(CO)6, by incorporation into the MCM-41 synthesis or by grafting of MoCl5 resulted in a low intake. The higher inclusion was obtained through impregnation and solid state ion exchange methods. At higher concentration, molybdenum oxide tended to cluster. In general, all silica MCM-41 behaves like amorphous silica