(579a) Enhancing Hydrocarbon Production through Synergistic Effect Between Biomass and Plastics during Catalytic Co-Pyrolysis

Enhancing Hydrocarbon Production through
Synergistic Effect between Biomass and Plastics during Catalytic Co-pyrolysis

Yuan Xue^a, Xianglan Bai^a

                                                 
^a Department
of Mechanical Engineering, Iowa State University

Producing
hydrocarbon fuels from biomass could help to relieve energy crisis and global
warming caused by burning fossil fuels. While catalytic pyrolysis is a cost
effective conversion technology, the yields of hydrocarbons obtained from biomass
are usually low due to high oxygen content and hydrogen deficient nature of
biomass. Waste plastics, on the other hand, represent abandoned energy source
and are often rich in hydrogen and low in oxygen content. Thus co-processing biomass
and waste plastics is not only good for sustainable energy and environmental
protection, but also improves feedstock quality. In this study, catalytic
co-pyrolysis of biomass and plastics was conducted using a tandem
micropyrolyzer equipped with an ex-situ catalytic bed. Catalysts include
HZSM-5, MoO₃ and the mixture of HZSM-5 and MoO₃,
respectively. Mass balance was reported and pyrolysis vapors, light gases, catalytic
coke and pyrolysis char were analyzed in detail to determine synergistic effects
between biomass and plastics. It was found that co-converting biomass and
plastics significantly improves both aromatic and aliphatic hydrocarbon yields by
synergistic effects. Combination of MoO₃ and HZSM-5 resulted in the strongest
synergistic effect during ex-situ catalytic pyrolysis. The synergistic effect
was contributed by multiple factors, such as Diels-Alder reaction among biomass
and plastic derivatives, contribution of plastic-derivatives to hydrocarbon
pool, enhanced free radical depolymerization, as well as hydrogen transfer from
plastics to biomass during thermal depolymerization.