Beeinflussung der katalytischen Eigenschaften von Al2O3?SiO2-Katalysatoren durch Alkalivergiftung

Effect of Alkali Contamination on the Catalytic Properties of Al₂O₃? Si₂ Catalytic properties of amorphous Al₂O₃? SiO₂ catalysts containing different amounts of Al₂O₃ in dehydration of isopropanol and cracking of cumene were examined after a defined contamination of the acid centers by sodium ethylate from alcoholic solution. In both reactions, the catalytic activity is decreased by treatment with sodium ethylate, the cracking of cumene being suppressed at a lower alkali concentration than the dehydration of isopropanol. In dehydration of isopropanol, the dependence of the catalytic activity on the alkali content is influenced strongly by the Al₂O₃ content of the catalysts. In the cracking of cumene, strongly acid Brönsted centers are active, whereas the dehydration of isopropanol proceeds by joint action of acid Lewis or Brönsted centers, respectively, with basic centers at the surface of the catalyst (hydroxide groups or oxygen anions).