The cracking performance of light hydrocarbon model compounds such as n-paraffins

i-paraffins

naphthalenes

aromatics and n-olefins on a mesoporous catalyst based on ZSM-5 molecular sieve was investigated in a small scale fixed bed reactor. The experimental results showed that the cracking performance in the order from good to poor was:n-olefins

n-paraffins

naphthalenes

i-paraffins

and aromatics. For n-paraffins

i-paraffins and naphthalenes

the yields of total light olefins were largely different whereas the selectivities of total light olefins were all around 56.57%. The main liquid components were pentene

benzene

toluene and xylene besides unreacted feed. In case of straight-run naphtha

the yield of ethylene plus propylene and the yield of total light olefins increased with the increase in reaction temperature and the decrease in weight hourly space velocity. At a condition of reaction temperature of 680℃

a weight hourly space velocity of 4.32 h-1 and a steam-to-oil weight ratio of 0.35

naphtha catalytic pyrolysis yielded 41.94% (mass) of total light olefins and 35.87% (mass) of ethylene plus propylene

which the ratio of propylene to ethylene at above 1.2 was much higher than that of naphtha steam cracking. A large amount of olefins and paraffins in the liquid sample of naphtha catalytic pyrolysis indicated that the liquid sample still had good cracking performance. A new characterization parameter (KF)

a function of H/C atomic ratio

relative density and molecular weight of feeds

was proposed to be more suitable than KCP for characterizing catalytic pyrolysis of light hydrocarbons.