THE APPLICATION OF METAL-OXIDE VAPOR SYNTHESIS TO THE PREPARATION OF MOLYBDENA CATALYSTS - THE ISOMERIZATION OF 1-HEXENE

A novel molybdena catalyst has been prepared by metal oxide vapour syn thesis (MOVS) and used to promote the vapour phase isomerization of 1- hexene to the two stereoisomeric forms of 2-hexene. Reproducible diffu sion-free isomerization rates are reported and compared to those achie ved using a commercial sample. Activity and product composition are pl otted as a function of time-on-stream and reaction temperature. The de gree of isomerization drops markedly over the first one to two hours a nd this is attributed to an occlusion of the active sites by carbonace ous deposits. The reaction is zero order with respect to 1-hexene conc entration and identical rates are achieved using a helium or nitrogen carrier gas. The MOVS system delivers appreciably higher reaction rate s compared with the commercial catalyst and apparent activation energy values of 40 and 30 kJ mol(-1) are recorded for the commercial and la boratory prepared catalysts, respectively. The observed isomeric yield s result from the direct conversion of 1-hexene where a surface promot ed interconversion of isomers can be discounted and the ultimate stere ospecificities are ascribed to steric effects.