Q: What is the mechanism of catalyst coking?

Q: What is the mechanism of catalyst coking?

Answer:The mechanism of coke formation is extremely complex, with numerous steps and complex reaction seriesCatalyst-The reaction objects are vastly different.

Generally, it includes dehydrogenation, isomerization, polymerization condensation, hydrogen transfer, cyclization, and aromatization reactions. In some early research works, reaction schemes were proposed for the generation of coke through polycyclic model compounds. The presence of olefins is considered the determining factor for accelerating coking formation in hydrogen transfer reactions. It is believed that olefins are receptors for hydrogen transfer reactions, and hydrogen plays an important role in inhibiting coke deposition. The amount and rate of coke production decrease in the following order: alkenes>polycyclic and polycyclic aromatic hydrocarbons>alkanes and cycloalkanes. It has been proven that there is an excellent correlation between the amount of coke generated and the logarithm of aromatic alkalinity. This indicates that the generation of coke is related to the acid-base properties of the reactant catalyst system.