T. Fukunaga et V. Ponec, ON THE ROLE OF ADDITIVES TO PLATINUM CATALYSTS FOR REFORMING REACTIONS, Applied catalysis. A, General, 154(1-2), 1997, pp. 207-219
The effect of various additives to platinum catalysts has been compare
d under standard reaction conditions at which aromatization of n-hexan
e occurs. With the same catalysts, (Pt/SiO2, Pt-K+/SiO2, Pt-Mg2+/SiO2,
Pt-KL zeolite, Pt-Mg2+-KL-zeolite, Pt/Al2O3, Pt-K+/Al2O3) dehydrogena
tion of cyclohexane to benzene has also been monitored. It has been es
tablished that the presence of K+- or Mg2+- additives can enhance the
aromatization activity, but the condition is that the additive-free ca
talyst is monofunctional. A discussion of the data presented together
with the relevant pieces of information from the literature leads to a
conclusion that the effect of K+ or Mg2+ is of electrostatic nature,
influencing the ring-closure.