Catalytic co-pyrolysis of herb residue and polypropylene for pyrolysis products upgrading and diversification using nickel-X/biochar and ZSM-5 (X = iron, cobalt, copper)

It is very important to find cheap and efficient catalysts for catalytic co-pyrolysis. Catalytic co-pyrolysis of herb residue (HR) and reused polypropylene (PP) using Ni-X/biochar and ZSM-5 (X = Fe, Co, Cu) was performed to produce pyrolysis oil, pyrolysis gas and carbon nanotubes (CNTs) in a two-stage fixed bed reactor. Bimetallic biochar catalysts exhibited higher catalytic activity due to their higher specific surface area (SBET) and more strong acid sites. NiCu/biochar significantly increased the yield of pyrolysis oil by enhancing Fischer-Tropsch synthesis. In addition, the stronger secondary cracking capacity of NiCu/biochar resulted in the highest content of hydrocarbons (80.47%) and C6-C11(61.10%), while the availability of higher content of carbon source gas also facilitated the formation of CNTs and H2 at back-end. The cheap and efficient NiCu/biochar catalyst has great potential in the application of catalytic pyrolysis, which is conducive to the large-scale promotion of biomass pyrolysis technology.