Strategic disposal of flood debris via CO₂-assisted catalytic pyrolysis

Recent abnormal climate changes resulted in the dramatic alternation of rainfall and flood patterns in many countries. The massive generation of flood debris, a mixture of soil (sediment), biomass, plastic, metal, and various hazardous materials, poses various environmental and public health problems. This study suggests a sustainable technical platform to convert the hazardous materials into value-added products. CO₂-assisted pyrolysis was used to thermally convert flood debris into syngas (H₂ and CO). CO₂ enhanced the syngas production due to gas phase homogeneous reactions (HRs) between CO₂ and volatile hydrocarbons evolved from pyrolysis of flood debris. For improvement of HRs in line with enhancement of syngas production, additional thermal energy and earth abundant catalyst were used. In particular, Ni/SiO₂ catalyst increased more than one order of magnitude higher syngas production, comparing to non-catalytic pyrolysis. Synergistic effect of CO₂ and Ni catalyst showed nearly 50% more production of syngas in reference to catalytic pyrolysis under N₂. During flood debris pyrolysis, compositional matrix of flood debris was also determined by detecting index chemicals of waste materials that cannot be identified by naked eyes. Thus, this study confirmed that CO₂-assisted pyrolysis is a useful tool for conversion of flood debris into value-added chemicals.