The effect of reaction condition on catalytic cracking of wheat straw pyrolysis volatiles over char-based Fe–Ni–Ca catalyst

In this study, the catalytic reforming of wheat straw pyrolysis volatiles over char-based Fe–Ni–Ca catalyst in a fixed bed reactor to investigate the influence of heating rate, pyrolysis temperature and catalyst calcination temperature on the yield of bio-oil, char and pyrolysis gas was presented. Char-based Fe–Ni–Ca catalysts had good activity for the removal of heavy oil, the heavy oil yield is 0.43% with 500 °C pyrolysis temperature and 5 °C/min heating rate. The maximum yield of hydrogen (288.41 mL/g) and combustible gas (hydrogen, methane and carbon monoxide; 403.45 mL/g) were obtained at a pyrolysis temperature of 800 °C and 10 °C/min heating rate. XPS, H 2 -TPR, XRD, TEM, SEM-EDS and BET were employed to analyze char-based Fe–Ni–Ca catalyst. Characterization results reveal that heating rate, pyrolysis temperature and catalyst calcination temperature had a significant effect on the distribution of active phase. Comparing to 800 °C, the diffraction peaks of Fe, Fe 0.64 Ni 0.36 , and Fe 2 O 3 become weak as 500 °C, the particle size changed from 23.17 nm to 24.34 nm. At 500 °C, the power of the diffraction peak decreases successively from Fe 2 O 3 , Fe, and Fe 0.64 Ni 0.36 . At 800 °C, the highest intensity of the diffraction peak is Fe, followed by Fe 2 O 3 . The high activity of char-based Fe–Ni–Ca catalyst is also attributed to the robust adsorption of CO 2 forming CaCO 3 species facilitated on the oxide ion vacancy site of CaO acting as oxygen exchange site. Also, the char-based Fe–Ni–Ca catalyst can be utilized as an appropriate candidate to crack the bio-oil. The pyrolysis temperature of 800 °C and the heating rate of 10 °C/min can be used as the best reaction conditions for industrial hydrogen production. • CaO was found not only a promoter, but also played a role in fixing CO 2 . • Char-based Fe–Ca–Ni catalyst had good activity for volatiles reforming of tar due to synergistic effect of Fe 2 O 3 , Fe and Fe 0.64 Ni 0.36 alloy. • The formation of CaO promoted dispersion of active sites (Fe, and Fe 0.64 Ni 0.36 ).