Bio-oil production from sequential two-step catalytic fast microwave-assisted biomass pyrolysis

•Sequential two-step catalytic fast microwave-assisted pyrolysis of corn stover was studied.•The pyrolysis and catalytic cracking and upgrading processes can be flexibly and independently controlled.•High selectivity of aromatic hydrocarbons was obtained by small catalyst loading.•HZSM-5 catalyst has good stability in the catalytic upgrading process.

A sequential two-step fast microwave-assisted pyrolysis (fMAP) for high quality bio-oil production was investigated. In the process, fMAP was followed by catalytic cracking and upgrading using a packed bed catalyst reactor with HZSM-5 as the catalyst. Effects of pyrolysis temperature, catalyst loading, and catalyst bed temperature on the product distribution were investigated. Results showed that maximum bio-oil and aromatic hydrocarbons yields were obtained when pyrolysis temperature reached 550 °C With the increase in the catalyst loading, the bio-oil yield decreased linearly while the aromatic hydrocarbons yield increased. The catalyst bed temperature also has a significant effect on the product chemical profiles. The aromatic hydrocarbons proportion of the bio-oil was found to increase with increasing catalyst bed temperature and reached its maximum of 26.20% at 425 °C. In addition, coke yield increased with increasing catalyst to biomass ratio and decreasing catalyst bed temperature.