CO2-assisted catalytic municipal sludge for carbonaceous biofuel via sub- and supercritical water gasification

Yaping Hu, Junhao Lin, Qinxiong Liao, Shichang Sun, Rui Ma, Lin Fang and Xiangli Liu

Energy, 2021, vol. 233, issue C

Abstract: This study uses CO2 as a reaction gas (99.999%) during the sub- (360 °C) and supercritical water gasification (380 °C–440 °C) of municipal sludge to realize the synergistic regeneration of CO2 and sludge into biofuels. The results showed that the reaction efficiency of sludge under CO2 atmosphere could be enhanced by adjusting the reaction parameters to increase the yield of biogas and bio-oil. Temperature was the primary driving force to promote the gasification reaction between CO2 and sludge. With increasing temperature, CO2 catalyzed the decomposition of fatty acids to form the biogas. An increase in the gasification temperature enhanced the reformation reaction between CO2 and the biogas, thus facilitating the generation of carbonaceous gases (CO, CH4, and C2–C4). Besides, CO2-assisted catalysis primarily facilitated the decomposition of organic matter by increasing the H+ concentration of reaction system. According to the elements distribution, more carbon was transferred to the biogas, and the oxygen content in the bio-oil was reduced in the presence of CO2. Correspondingly, the lower heating value of biogas and bio-oil increased to 30.18 MJ/kg and 6.32 MJ/Nm3. Using CO2 as a reaction gas has the potential to optimize the quality of sludge-derived biofuels and convert CO2 into carbonaceous fuels.

Keywords: CO2 reaction gas; Municipal sludge; Reaction parameters; Carbon element migration; Biofuels (search for similar items in EconPapers)
Date: 2021
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:233:y:2021:i:c:s0360544221014328

DOI: 10.1016/j.energy.2021.121184

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