Effect of Re on product yields and deactivation patterns of naphtha reforming catalyst

The effect of rhenium concentration on the activity and stability of Pt–Re/Al2O3 catalysts used in naphtha reforming were studied by varying the rhenium concentration. The samples were prepared by the co-impregnation method on chloride alumina. The platinum content was 0.3 wt.%, and the rhenium loading was varied to obtain Re/Pt weight ratios of 1.0, 1.5, 2.0, 2.5 and 3. Re loading greatly influenced the catalytic properties and product yields in naphtha reforming. TPR profiles indicated the increase in hydrogen uptake, but decrease in reducibility of rhenium with increase of rhenium loading. At low rhenium loadings, the catalyst exhibited the presence of two groups of rhenium reduced at two different temperatures, while the peaks are merged in to a single sharp peak at higher rhenium loadings. Increase in aromatic yields and decrease in cracking yields was observed up to 0.6 wt.% rhenium loading (Re/Pt weight ratio = 2.0). Further increase of Re caused decrease in xylene and C9+ with simultaneous increase of benzene, toluene, methane and ethane yields. The catalyst with 0.6 wt.% rhenium exhibited best aromatic yields and highest hours-on-oil performance.

Rhenium loading up to 0.6 wt.% (Re/Pt = 2) facilitated the improvement in hydrogen uptake and hours-on-oil stability of the Pt–Re/Al2O3 naphtha reforming catalyst, while above the 0.6 wt.% loading, the hydrogen uptake as well as catalyst stability is decreased.Figure optionsDownload as PowerPoint slide