Effects of Pt site distributions on the catalytic performance of Pt/SAPO-11 for n-dodecane hydroisomerization

A series Pt/SAPO-11 were prepared by using incipient wetness impregnation (IWI) and colloidal impregnation (CI) methods. TEM, STEM, CO-FTIR and H-2 chemisorption were employed to study the effects of preparation method on the distributions of Pt sites. The catalytic performance of Pt/SAPO-11 was evaluated by using n-dodecane as the model reactant in a fixed-bed reactor. The characterization results suggested that the Pt sites on IWI catalyst could be mainly distributed near the micropore mouth of SAPO-11, while the Pt sites on CI catalyst could be mainly distributed on the external surface. In n-dodecane hydroisomerization, IWI catalyst showed higher activity and isomerization selectivity than CI catalyst. Possible relationships between the distributions of Pt sites and the catalytic performance of Pt/SAPO-11 were discussed.