Enhancement of hydrocarbons production through co-pyrolysis of acid-treated biomass and waste tire in a fixed bed reactor

[Display omitted] •86% K, 58% Ca, 48% Mg, 58% Na and 35% Fe were removed by acid treatment.•Synergistic effect was more significant for treated cotton stalk than its raw form.•Co-pyrolysis of treated cotton stalk yielded 18% more HCs in oil.•Quantity of oxygenates in oil significantly decreased with acid treatment. The elution of metallic content from cotton stalk (CS) and its co-pyrolysis with waste tires (WT) was investigated in fixed bed reactor. Hydrochloric acid (HCl) was used for leaching and successful removal of metals from cotton stalk was observed. Removal efficiencies of 86%, 58%, 48%, 58% and 35% for potassium, calcium, magnesium, sodium, and iron metals were achieved, respectively. Pyrolysis and co-pyrolysis using various mixing ratios of raw (R-CS) and acid washed cotton stalk (W-CS) with waste tire were carried out at 550 °C. Co-pyrolyzing W-CS with WT not only resulted in increased liquid yield with reduced char and gas yields, but also improved the quality of pyrolytic oil evincing the occurrence of strong positive synergistic effect. The addition of WT reduced oxygenates, density and water content of oil whilst pH and calorific value are increased compared to both, R-CS and W-CS pyrolytic oils. Relative percentage area of hydrocarbons increased to 65% in co-pyrolysis of WT with W-CS as compared to 47% for that of R-CS at optimum blend ratio (CS:WT 1:3). Likewise, 19% higher reduction in oxygenated compounds was observed in W-CS and WT co-pyrolytic oil. Co-pyrolyzing WT with R-CS and W-CS resulted in improved quality of oil. However, the synergistic effect was less significant for R-CS suggesting that the presence of intrinsic metals in R-CS hampered the occurrence of synergistic effects.