High-efficiency and low-pollutant waste polystyrene and waste polystyrene foam gasification: Comprehensive comparison analysis, multi-objective optimization and multi-criteria decision analysis

Gasification of carbonaceous materials leads to an efficient hydrogen-rich syngas and this promising technology has been widely studied for biomass and municipal solid waste. However, polymeric foam waste gasification has not been addressed well and needs to be developed. A comparative analysis between waste plastic and waste polymeric foam gasification is the main objective and novelty of this study. Air gasification of waste polystyrene and waste polystyrene foam was modeled and investigated with respect to gasification temperature, equivalence ratio and moisture content. Response surface methodology was employed for multi-objective optimization of gasification processes. The results showed that waste polystyrene foam gasification had better performance compared with waste polystyrene gasification from hydrogen production (1.588 g versus 1.509 g from one mole of feedstock) and energy efficiency (87.89 % versus 84.00 %) viewpoints. On the other hand, waste polystyrene gasification resulted in lower carbon dioxide emission and higher carbon monoxide. Decision analysis based on multi-criteria concepts indicated better performance of waste polystyrene foam gasification.