焦炭
沸石
成核
催化作用
化学工程
化学
微晶
冷凝
氢
无机化学
材料科学
有机化学
结晶学
热力学
物理
工程类
作者
M. Guisnet,P. Magnoux,Kjell Moljord
出处
期刊:Acs Symposium Series
日期:1996-06-06
卷期号:: 77-90
被引量:4
标识
DOI:10.1021/bk-1996-0634.ch005
摘要
The formation of coke during hydrocarbon conversion on zeolite catalysts can be considered as a nucleation-growth process. Nucleation is due to the retention in the zeolite micropores of coke precursors (heavy secondary reaction products). At high temperature the retention is due to trapping in the cavities or at channel intersections ; condensation and hydrogen transfer reactions are involved both in the formation of coke precursors and in their growth. As with other catalysts, deactivation of zeolite catalysts occurs either through site coverage or through pore blockage. Pore blockage is the only mode of deactivation of monodimensional zeolites and of zeolites with trap cavities (large cavities with small apertures), both types deactivating very rapidly. With the other types of zeolites at low coke contents deactivation is due to site coverage, while at high coke contents it is due to a blockage of the pores by coke deposits on the outer surface of the crystallites.
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