Catalytic pyrolysis of polypropylene plastics and product properties with Fe-loaded sludge biochar

Aiming at the problems of complex plastic components, unstable components and difficult quality control of pyrolysis oil production, this study used municipal sludge as raw material to prepare Fe-loaded sludge-based biochar catalyst, and conducted research on the experimental route of promoting tar cracking and syngas production by catalytic pyrolysis of polypropylene plastic (PP). The tar removal effect in PP pyrolysis products, the key components of H2-rich syngas, and the effect of catalytic pyrolysis process on the surface characteristics of sludge-based biochar were analyzed. The results showed that the sludge-based biochar with FeCl3 impregnation ratio of 5% (mass fraction, calculated as Fe) could significantly promote the catalytic pyrolysis of PP to produce hydrogen. The hydrogen yield reached 17.39mmol/gplastic, which was higher than the biochar without Fe-loaded catalysis control group of 268.43% and the pure PP pyrolysis control group of 2046.91%, respectively. The catalytic pyrolysis process strengthened the tar cracking, and the tar cracking rate reached 29.65%. The relative proportion of alcohols in the tar component decreased, and the relative proportion of olefins and halogenated esters increased. At the same time, a special thin-layered pore structure appeared on the surface of the sludge-based biochar after catalytic pyrolysis, and the specific surface area increased to 225.90m2/g. XPS analysis found that the relative proportion of carbon-oxygen functional groups on the surface of sludge-based biochar bound to carbon, lattice oxygen and carboxyl oxygen increased, which proved that more active sites appeared at this Fe impregnation ratio. © 2023 Chemical Industry Press. All rights reserved.