Secondary catalytic reactions of primary volatiles from oil shale pyrolysis were characterized by using a two-stage reactor to study the effects of different catalytic materials

reaction atmospheres and residence time on oil/gas yield and quality.The results showed that comparison with FCC catalyst as bed materials in the 2nd stage

the shale ash possessed relatively moderate activity for adjusting the secondary reaction of pyrolysis volatiles in the applied range of residence time.Using steam as the reaction atmosphere could further enhance the liquid yield by 5% and suppress the C2-C3 hydrocarbons in the cracked gas.The heavy oil fractions

such as vacuum gas oil (VGO

>350℃)

could be converted into light oil fractions by the catalytic effects of shale ash

and correspondingly the boiling range of pyrolysis oil tended to be lighter with higher residence time.Oil components analyzed with GC-MS demonstrated that steam could effectively inhibit the over-cracking of aliphatic hydrocarbons at shorter residence time (<3 s)

and thus increase the gasoline and diesel fractions by over 20% compared with the N2 atmosphere.However

at higher residence time (3-5 s) the VGO fractions were prone to be condensed as coke

and as a result profoundly decreased the pyrolysis oil yield.