Catalytic Fast Pyrolysis of Wheat Stalk with Transition Metal Nitrides to Upgrade the Pyrolytic Products

Analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique was employed to explore lignocellulosic biomass catalytic pyrolysis with transition metal nitride catalysts (TiN, ZrN, and W2N). Various factors like suitability of catalysts, catalyst to biomass (C/B) ratio and pyrolysis temperature on pyrolytic product distribution were investigated for their roles in improvement of fuel properties of pyrolysis oil. The results indicated that TiN significantly facilitated the cleavage of lignin to produce phenolic compounds. It also devolatilized holocellulose to produce organic volatile compounds by reducing linear aldehydes while increasing furans and cyclopentanones. The maximum volatile product yield was recorded when the pyrolysis temperature was 500 °C and C/B ratio was 1. It was further noted that maximum contents of phenolics, cyclopentanones and furans produced from the catalytic process were 1.53, 1.37 and 1.80 times higher than those in the noncatalytic process, respectively. In addition, the content of linear aldehydes was reduced expressively to 3.32 times compared to non-catalytic process. The maximal content of stable phenolics obtained from the catalytic process was 2.31 times greater than non-catalytic process. Comparing overall effect, TiN was most capable to upgrade bio-oil by lowering oxygen content and increasing phenolics, cyclopentanones and furans. It expressed promising catalytic properties towards high grade pyrolysis oil.