Initiation of chain reaction in catalytic pyrolysis of n-heptane over zeolite catalysts

Experiments of n-heptane catalytic pyrolysis over zeolite catalysts were conducted on a laboratory fixed fluidized bed reactor. The effects of reaction temperature, the number of active site and zeolite type of the catalyst on product slate were investigated, as well as the initiation of chain reaction was analyzed. Results showed that during n-heptane catalytic pyrolysis over ZRP zeolite catalyst, the positions and progress of C-C bond attacked by a proton in the initiation reaction was varied with reaction temperature obviously. With the increase of reaction temperature, the protonized position shifted from the C-C bond adjacent to center to that located at C-terminal, leading to various product slates. With the increase of activity (acidity) sites in catalyst, the initiation of chain reaction could be speeded up and the attacked positions tended to the center of carbon chain. Compared with Y and Beta zeolite catalysts, ZRP zeolite catalyst had more strong Brönsted acid sites, which was in favor of initiating chain reaction occurring at the center of carbon chain.