Pyrolysis and in-line chemical looping cracking-gasification of face mask waste into hydrogen-rich syngas

Abstract

The thermochemical recycling of face mask (FM) waste into syngas shows great potential for the harmless treating, rapid quantity reducing and resource utilization. In this study, a novel pyrolysis and chemical looping cracking-gasification method was developed to achieve the highly efficient conversion of two disposable surgical masks (White FM and Blue FM) and N95 mask into syngas. The redox catalysts of Fe/Co/Ni oxide supported with Al₂O₃ were synthesized by the co-precipitation method with the molar ratio of 2:1 for the conversion of FMs. Results showed that the pyrolysis and in-line chemical looping cracking-gasification method could efficiently convert White FM into syngas with the H₂ productivity of 93.84 mmol/g with Fe2Al. Moreover, the quality of the produced syngas was very high with the concentration of 92.37 % and the H₂/CO ratio of 2.03, which was the ideal feedstock for the Fischer-Tropsch synthesis into chemical compounds. Fe2Al was found to perform the best syngas properties compared with Co2Al and Ni2Al due to its higher reduction degree at chemical looping cracking step, and this would produce more H₂ via steam-iron reaction during chemical looping gasification. The hydrocarbon vapors react with the redox catalyst, initially depositing carbon via chemical looping cracking, followed by syngas production and catalyst regeneration through steam-char gasification and steam-iron reoxidation reactions. It provided a promising technology for the recycling of FM with high carbon conversion efficiency and syngas concentration to produce syngas with H₂/CO ratio of about 2.