Pyrolysis of municipal solid waste: A kinetic study through multi-step reaction models

Area of Science:

• Chemical Engineering
• Environmental Science
• Materials Science

Background:

• Municipal Solid Waste (MSW) pyrolysis is a promising waste-to-energy technology.
• Understanding the complex degradation kinetics of MSW is crucial for process optimization.
• Previous studies often simplify the multi-component nature of MSW pyrolysis.

Purpose of the Study:

• To conduct a comprehensive kinetic analysis of MSW residue pyrolysis.
• To compare various kinetic modeling approaches for multi-step degradation.
• To identify and quantify products from distinct pyrolysis stages.

Main Methods:

• Utilized five isoconversional methods (Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall, Starink, Friedman, Vyazovkin).
• Applied Mathematical Deconvolution Analysis and Independent Parallel Reaction Model.
• Performed analytical pyrolysis to identify and semi-quantify pyrolysis products.

Main Results:

• Identified two active pyrolysis steps: biomass (150-400°C) and plastics (400-520°C).
• Obtained activation energies of ~240 kJ/mol for biomass and ~250 kJ/mol for plastics.
• Biomass degradation followed a third-order kinetic model, while plastics followed a first-order model.
• Pyrolysis yielded 64% hydrocarbons (24% aromatic) and 20% oxygenated compounds (ketones, furans, acids).

Conclusions:

• The multi-step kinetic analysis provides a detailed understanding of MSW pyrolysis.
• Kinetic parameters differ significantly between biomass and plastic fractions.
• MSW pyrolysis is an effective route for producing valuable hydrocarbons and oxygenated compounds.