Pyrolysis/Non-thermal Plasma/Catalysis Processing of Refuse-Derived Fuel for Upgraded Oil and Gas Production

Refuse-derived fuel (RDF) produced from the processing of municipal solid waste (MSW) has a high content of biomass and plastics. Pyrolysis of RDF produces a bio-oil which is highly oxygenated, viscous, acidic with a high moisture content and unsuitable for direct use in conventional combustion systems and consequently requires upgrading. A novel process of pyrolysis with non-thermal plasma/catalysis has been developed to produce de-oxygenated bio-oils and gases from RDF. The volatiles from the pyrolysis stage are passed directly to a non-thermal plasma/catalytic reactor where upgrading of the pyrolysis volatiles takes place. Detailed analysis of the product oils and gases is presented in relation to process conditions and in the presence of different catalysts (TiO₂, MCM-41, ZSM-5, and Al₂O₃). Even in the absence of a catalyst, the presence of the non-thermal plasma resulted in high yields of CO and CO₂ gases and reduced bio-oil oxygen content, confirming deoxygenation of the RDF pyrolysis volatiles. The addition of catalysts MCM-41 and ZSM-5 generated the highest yields of CO, CO₂, and H₂ due to the synergy between catalyst and plasma. The catalysts ranked in terms of total oxygenated oil yield are as follows: MCM-41 < ZSM-5 < TiO₂ < Al₂O₃. Pyrolysis of RDF produces an oil containing oxygenated species from biomass and hydrocarbon species from plastics. The non-thermal plasma generates high energy electrons which generate radicals and intermediates from the pyrolysis volatiles which synergistically interact with the catalysts to enable deoxygenation of the oxygenated hydrocarbons through decarboxylation and decarbonylation reactions.