“Coking”的意思、由来-开放百科全书

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Coking

释义

References

{{related|Coke (fuel), a carbon-rich solid obtained by coal pyrolysis}}Coking is the deposition of carbon-rich solids. In heterogeneous catalysis, the process is undesirable because the clinker blocks the catalytic sites. Coking is characteristic of high temperature reactions involving hydrocarbons feedstocks. Typically coking is reversed by combustion, provided that the catalyst will tolerate such.^[1]

A simplified equation for coking is shown in the case of ethylene:

3 C₂H₄ → 2 C ("coke") + 2 C₂H₆

A more realistic but complex view involves the alkylation of an aromatic ring of a coke nucleus. Acidic catalysts are thus especially prone to coking because they are effective at generating carbocations (i.e., alkylating agents).

Coking is one of several mechanisms for the deactivation of a heterogeneous catalyst. Other mechanisms include sintering, poisoning, and solid-state transformation of the catalyst.^[2]^[3]

References

1. ^{{cite journal|title=“Coking” of zeolites during methanol conversion: Basic reactions of the MTO-, MTP- and MTG processes|journal=Catalysis Today|volume=154|pages=183-194|doi=10.1016/j.cattod.2010.05.012|author=H. Schultz}}
2. ^{{cite journal|title=Catalyst Deactivation|authors=Forzatti, P.; Lietti, L.|journal=Catalysis Today|year=1999|volume=52|pages=165-181|doi=10.1016/S0920-5861(99)00074-7}}
3. ^{{cite journal|last1=Bartholomew|first1=Calvin H|title=Mechanisms of Catalyst Deactivation|journal=Applied Catalysis A: General|volume=212|issue=1–2|pages=17–60|doi=10.1016/S0926-860X(00)00843-7|year=2001}}

2 : Coking works|Catalysis

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