Saturation of aromatics and aromatization of C3 and C4 hydrocarbons over metal loaded pillared clay catalysts

Saturation of aromatics (benzene, xylene or mesitylene) over Pt (or Pd)/PLC catalysts and commercial Pt (or Pd)/gamma-Al2O3 was studied. The results show that the benzene hydrogenation activity of Pt (or Pd)/PLC is similar to that of Pt (or Pd)/gamma-Al2O3. Pt (or Pd)/PLC shows the shape-selectivity in the hydrogenation of xylene and mesitylene because of its regular larger pore structure. The bimetallic Pt-Pd/Al-PLC catalyst has a higher activity for hydrogen saturation and a stronger stability to sulfur poisoning. The study of C-3 and C-4 hydrocarbon aromatization over Zn/Al-PLC and Zn/HZSM-5 shows that the Zn/HZSM-5 has a much higher activity than the Zn/Al-PLC catalyst due to their characteristic difference in acidity. In addition, it is found that C-3 is mainly converted to benzene and C-4 to xylene over Zn/PLC, while both C-3 and C-4 are mostly converted to toluene over Zn/HZSM-5, Among the pillared clays, the Ga-PLC is most effective for aromatization. In order to improve the C-3 and C-4 aromatization property over Zn/Al-CLM, bimetallic catalysts were studied. Combining Ga3+ and Pt4+ improves the selectivity of aromatics as well as the total conversion. (C) 1999 Elsevier Science B.V. All rights reserved.