Study on the physicochemical and isomerization property of Pt/SAPO-11 catalysts promoted by metallic additive

Monometallic catalyst Pt/SAPO-11 was prepared by impregnation method. Bimetallic catalysts including LaPt/SAPO-11, CePt/SAPO-11 and SnPt/SAPO-11 were prepared by sequential impregnation method. X-ray diffraction (XRD), nitrogen adsorption, temperatureprogrammed desorption of ammonia (NH₃-TPD), chemisorption of hydrogen and Fourier transform infrared spectroscopy (FT-IR) techniques were employed to characterize the catalyst. The results showed that BET surface areas, microporous volume, the amount of Bronsted acid and the total acidity of catalysts decreased slightly with the addition of metal additive La, Ce or Sn. However, the addition could lead to an increase in the amount of Lewis acid. Meanwhile, the introduction of the additive was feasible to promote the dispersity of Pt. In addition, the catalytic performances of catalysts for the hydroisomerization of n-heptane were studied. At 360℃, addition of La and Ce to Pt/SAPO-11 catalyst could increase its conversion of n-heptane from 65.14% to 77.40% and 78.12% respectively, and yield of i-C₇ from 61.67% to 69.72% and 68.48%, respectively. While the conversion of n-heptane and yield of i-C₇ over SnPt/SAPO-11 catalyst was 63.22% and 59.09% respectively.