Isothermal gasification kinetics of char from municipal solid waste ingredients using the thermo-gravimetric analysis

Abstract

The study focused on exploring the kinetic parameters of wastes in gasification experiments with CO2. The feedstock of mixtures was pyrolyzed using the thermo-gravimetric analyzer at different temperatures under an inert environment. The proximate analysis of the sawdust and Polyethylene revealed that biomass contains carbon and oxygen in almost equal amounts, therefore highlighting the problem of high oxygen content in its bio-oil. Polyethylene evidently has no oxygen content, making it an ideal co-feedstock for pyrolysis by TGA. On the other hand, Polyethylene contains all its organic matter in volatile form and does not contribute to forming char. The pyrolysis behavior was assessed by estimating the kinetic parameters, using the isothermal models of Zero-order (R2 = 0.978), Contracting area (R2 = 0.962), and Avrami-Erofeev (R2 = 0.960), Power Law (R2 = 0.960), indicating the most suitable models for CO2 gasification-pyrolysis. In conclusion, the low activation energy of wastes degradation using the model-free method (8.079 × 107 J kmol−1) in the low range of the wood waste activation energy, indicating the suitability of both materials for co-pyrolysis because of the synergistic effects between biomass and plastics, uniformity between materials, and also the high surface area of the mixture (101 m2 g−1). Finally, the TGA model is used to assess the kinetic parameters of these chars by gasification method.

Keywords

• TGA
• Sawdust
• Polyethylene
• Approximate analysis
• Kinetic models
• Isotherm