Co-pyrolysis of Chinese herb residue and polypropylene over Ni, Fe, Co and Cu/AC: Co-production and formation mechanism of carbon nanomaterials, liquid oil and pyrolysis gas

Abstract

The preparation of high-value fuels and carbon nanomaterials (CNMs) by co-pyrolysis of Chinese herb residue (CHR) and polypropylene (PP) is conducive to the improvement of environment and energy problems. The effect of monometallic (Ni, Fe, Co, Cu) and bimetallic (Ni/Fe, Ni/Co, Ni/Cu) loaded on activated carbon (AC) catalysts on the pyrolysis products was investigated in a two-stage fixed bed. The results showed that the synergistic effect of bimetals improved the quality of pyrolysis products. In particular, NiCo/AC significantly promoted the removal of F and improved the quality of liquid oil. Moreover, the content of over C20 in the Ni/Co group was the lowest, indicating that the secondary cracking of macromolecules was promoted. NiCo/AC also improved the yield and quality of pyrolysis gas. The content of H2 in Ni/Co group increased to 27.82%. In addition, Ni/Co group had the highest yield (more than 4 times that of blank group) and quality (ID/IG = 1.019) of CNMs. The pyrolysis gas obtained from different front-end catalytic has a great influence on the formation of back-end CNMs. The high CH4 promoted the formation of CNMs. A unique 3D graphitic carbon (GC) network was finally formed in high temperature.