A new insight into high quality syngas production from co-pyrolysis of light bio-oil leached bamboo and heavy bio-oil using response surface methodology

•Syngas is produced by co-pyrolysis of heavy bio-oil and light bio-oil leached bamboo.•The yield and properties of syngas are studied using response surface methodology.•Co-pyrolysis improves the yield and H2 + CO content of syngas.•Regression equations between syngas properties and variable values are obtained.•The optimal yield of syngas is up to 42.92 wt% with a HHV of 19.26 MJ/Nm3. Syngas, bio-oil, and biochar are three-phase products yielded from biomass pyrolysis. As a clean fuel, syngas has great potential value within the background of carbon neutrality. However, little attention has been paid to syngas compared with other pyrolysis products. In this study, a novel method for high yield production of syngas with high calorific value production has been proposed, in the context of light bio-oil (LB) leached bamboo and heavy bio-oil (HB) co-pyrolysis. The effects of three experimental variables (mass ratio, pyrolysis temperature, and residence time) on the yield and properties of syngas were investigated using response surface methodology. Results showed that under the typical experimental conditions (mass ratio 1:1, 550 °C, and residence time of 17.5 min), the experimental gas yield (23.14 wt%) and H2 + CO content (41.18 vol%) of HB and raw bamboo co-pyrolysis were 4.87 wt% and 2.24 vol% higher than the theoretical value, respectively. Notably, LB leaching pretreatment effectively removed biomass ash and changed the pyrolysis pathway. A more significant synergistic effect was observed during the co-pyrolysis of HB and LB leached bamboo, leading to a higher gas yield and a higher combustible gases content. High-quality syngas enriched in H2 and CO was obtained. Under the optimal conditions (mass ratio 1:3.09, 700 °C, and residence time of 19 min), the yield of syngas was up to 42.92 wt% with a high HHV of 19.26 MJ/Nm3, and the H2 + CO content was 63.74 vol%. Eventually, the regression equations between syngas properties and variable values were obtained. The method proposed in this study could herein provide a basis for the utilization of different fractions of bio-oil, as well as the co-pyrolysis for high quality syngas production.