Aiming at the generation mechanism and influencing factors of methane in catalytic cracking process,C8 alkanes were used as model compounds to study the effects of reaction temperature,octane isomers and three kinds of catalytic materials including ZSM-5,MPZ and pseudo-boehmite on methane selectivity in the catalytic cracking process.The results reveal that the occurrence probability of paths for forming methane in the protonation cracking process of alkane molecules grows with the increase of reaction temperature;the molecular structure of raw materials is an essential factor for determining the methane selectivity during catalytic cracking;the methane selectivity increases with the increase of the number of alkyl side chains in raw material molecules;the isomerization reaction,in which the carbonium ions are decreased,can inhibit the excessive methane formation.The structural characteristics and acidity of catalytic materials are key influencing factors of methane selectivity;the larger bore diameter and specific surface area provide more active sites while promoting in-diffusion,which can effectively increase the conversion rate of reactant molecules,and its influence on methane selectivity is not significant,whereas Lewis acid plays an important catalytic role in the formation of methane.
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