Catalytic pyrolysis of cow manure over a Ni/SiO₂ catalyst using CO₂ as a reaction medium

The massive production of manures in the livestock industry gives rise to detrimental effects on rural environment due to the contamination of soil and streams from the disposed manure. This study directly utilizes an animal manure as a source for syngas production so that it can be used as energy or fuel instead of being discarded. Cow manure (CM) was employed as the feedstock for syngas generation via thermo-chemical process in the CO₂ environment. In addition, the mechanistic roles of CO₂ in CM pyrolysis were examined. It was found that H₂ and CO gases were formed via dehydrogenation and deoxygenation at ≤ 500 °C in both CO₂ and N₂ conditions, while CO₂ expedited the substantial generation of CO at ≥ 600 °C via the homogeneous reaction of volatile organic compounds (VOCs). CO₂ was less likely to affect the homogeneous reaction with VOCs at ≤ 500 °C, but it was effective synergistically with a Ni/SiO₂ catalyst in the temperature range. CO₂-cofeeding catalytic pyrolysis of CM showed 25% more gas formation than CM catalytic pyrolysis in the N₂ condition. Therefore, this sustainable approach suggests the feasibility of the establishment of a CM-to-energy platform for syngas generation in the presence of greenhouse gas.