A question about the hydrocracking reaction mechanism?
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Regarding the mechanism of hydrocracking reactions, some sources state that: \"For a given type of reactant, macromolecules react much faster than small molecules; this is why the components of the feed that fall within the product fraction range do not actually undergo conversion after passing through the cracker.\" Can this be understood as meaning that, \"for example, if naphtha is mixed into the feedstock and fed in a second time, then the naphtha will not undergo any conversion reactions\"? Or is the previous sentence simply wrong? Please ask an expert to explain it, thank you.
The first sentence is contradictory. It was said earlier that \"macromolecules react much faster than small molecules,\" but this does not mean that small molecules do not react at all. In actual work, it is acceptable to feed the material again if the results after hydrogenation are not satisfactory.
The carbon-carbon bonds in macromolecules have low bond energy and are prone to cracking.
The reaction rate depends not only on the size of the molecules but also on their structure, as well as on the catalyst used. It’s a very complex issue; however, it’s definitely incorrect to say that secondary feeding of naphtha will result in no reaction.