Comparative experiments on the catalytic pyrolysis of herb residue by K₂CO₃ and K₂FeO₄

The effects of K₂CO₃ (PC) and K₂FeO₄ (PF) on the catalytic pyrolysis of herb residue were investigated by using a thermogravimetric analyser, online mass spectrometry and a fixed-bed reactor, using herb residue as the raw material and loaded with PF and PC catalysts respectively by impregnation. The results showed that both PC and PF lowered the pyrolysis reaction temperature of the herb, enhanced the water vapour reforming reaction and significantly increased the pyrolysis gas yield and H₂ content. At 500 ℃, the catalyst promoted the production of H₂ and increased the H₂/CO ratio of the pyrolysis gas from 0 to 1.29 and 1.92, respectively; at 700 ℃, PC and PF can significantly reduce the liquid-phase yield and increase the H₂/CO of the gas product, with PF being more effective, reducing the liquid-phase yield by 30.9% and increasing the H₂/CO increased by 38.5%. However, PF will decompose and release oxygen during the pyrolysis process, which makes NO emissions increase.