Offering a new option to valorize hen manure by CO2-assisted catalytic pyrolysis over biochar and metal catalysts

The huge generation of animal manures from livestock industries has resulted in detrimental environmental effects such as soil and stream contaminations in line with emissions of greenhouse gases (i.e., CH4 and CO2). To alleviate the environmental problems from the animal manure waste, this study proposed a new option for disposal of hen manure waste and its valorization as energy and catalyst. To make this platform more environmentally sound, CO2 was used as a feedstock to control the pyrogenic products (biochar, syngas, and biocrude) from HM. CO2 contributed to more thermal cracking of volatile matters (VMs) evolved from HM pyrolysis into syngas in reference to pyrolysis in N2. In detail, enhanced CO production from gas phase homogeneous reactions (HRs) between CO2 with VMs was observed. To improve the reaction kinetics for syngas formations, HM biochar was used as a catalyst. HM biochar substantially expedited the syngas formation due to presence of alkaline species. The catalytic capability of HM biochar was nearly the half of Ni catalyst, though the price of HM is a few orders of magnitude lower. This offers that CO2-assisted pyrolysis with HM biochar could be considered an environmentally and economically viable way for syngas formation from biomass waste.