Reaction of 2,2-dimethylpropane with dihydrogen over silica-supported Pdsingle bondFe catalysts Original Research Article

The reaction of 2,2-dimethylpropane with dihydrogen has been studied over a series of well-characterized Pdsingle bondFe/SiO2 catalysts. The overall activity of Pdsingle bondFe/SiO2 strongly decreases with increasing iron content. At the same time, the selectivity towards isomerization passes through a maximum, resembling the catalytic behaviour of Pdsingle bondCo/SiO2. The effect of time-on-stream on the catalytic activity was also investigated. The samples rich in iron, i.e. with the Fe content > 50 at.-%, become gradually more active whereas the samples rich in palladium deactivate with increasing time-on-stream. All these results demonstrate the presence of dispersed Pdsingle bondFe alloys in samples reduced at 450°C. In the case of iron-rich Pdsingle bondFe/SiO2 catalysts, oxidation prior to reduction causes a pronounced decrease in isomerization selectivity. It seems that the oxidation leads to a considerable separation of two metal components and a subsequent reduction does not fully restore the extent of alloying of Pd with Fe in samples reduced at 450°C.