固体超强酸在催化正己烷异构化反应中失活的研究

研究了固体超强酸催化剂SO4^2-／ZrO2及负载型SO4^2-／ZrO2-SiO2催化剂在催化正己烷异构化反应中的失活与再生问题。结果表明，在催化正己烷异构化反应过程中，催化剂SO4^2-／ZrO2和SO4^2-／ZrO2-SiO2均存在明显的失活现象。失活的主要原因是积炭覆盖了催化剂表面的超强酸中心，但可通过烧炭的方法除去表面的积炭而使催化剂再生。再生后的催化剂的活性并没有明显降低。催化剂SO4^2-／ZrO2-SiO2的催化活性明显低于SO4^2-／ZrO2，催化剂制备过程中焙烧温度有显著的影响。通过对催化剂积炭过程的动力学分析，提出了失活过程的模型，并依此计算了固体超强酸催化烷烃异构化反应的积炭反应的表观活化能。

STUDY ON DEACTIVATION OF SOLID SUPERACID IN CATALYTIC REACTION OF n-HEXANE

The deactivation and regeneration of solid superacid catalyst SO_4~~(2-)/ZrO_2 and supported catalyst SO_4~(2-)/ZrO_2-SiO_2 in n-hexane isomerization reaction were studied.Obvious deactivation of SO__4~~(2-)/ZrO_2 and SO__4~~(2-)/ZrO_2-SiO_2 was observed in n-hexane isomerization reaction.The the coke deposited on superacid sites during isomerization reaction was responsible for the loss of catalytic activity.Regeneration was carried out by burning off the coke on catalyst surface.No marked difference of catalytic activity was seen between fresh and regenerated catalysts.The catalytic activity of SO__4~~(2-)/ZrO_2-SiO_2 was lower than that of SO_4~~(2-)/ZrO_2,in accordance with the strength and amount of the superacidic sites on SO__4~~(2-)/ZrO_2-SiO_2.Calcination temperature during the preparation of SO_4~~(2-)/ZrO_2-SiO_2 obviously affected its catalysis activity.The model describing the deactivation process was obtained by using kinetic analysis of coking process during catalytic reaction.With this model the apparent activation energy of coking reaction was calculated out.For SO__4~~(2-)/ZrO_2 catalyst,the apparent activation energy of coking reaction was 13.2 kJ/mol, and for SO__4~~(2-)/ZrO_2-SiO_2 it was 17.3?kJ/mol.