Hydrogen-rich bio-gas generation and optimization in relation to heavy metals immobilization during Pd-catalyzed supercritical water gasification of sludge

Junhao Lin, Shichang Sun, Chongwei Cui, Rui Ma, Lin Fang, Peixin Zhang, Zonggang Quan, Xin Song, Jianglong Yan and Juan Luo

Energy, 2019, vol. 189, issue C

Abstract: This study aimed to investigate the relationship between the immobilization efficiency of heavy metals (HMs) and the generation of bio-gas under different catalyzing conditions during the supercritical water gasification of sludge. Results showed that catalysts could promote the decomposition of organic matters to improve the yield of bio-gas and the order of the catalysts in terms of H2 selectivity was Pd > CaO > AlCl3. Pd catalyst not only promoted the generation of hydrogen-rich bio-gas but also enhanced the immobilization efficiency of HMs. This was because the Pd catalyst facilitate the steam reforming reaction of the high-molecular-weight organic matters while promoting the combination of HMs with mineral components to form stable crystalline compounds. When the addition amount of Pd catalyst was 10 wt %, the yield of hydrogen-rich bio-gas increased from 35.74 wt% to 46.88 wt%, and the leaching concentration of Zn, Cu, and Cr decreased significantly to 1.22 mg/L, 0.55 mg/L and 0.38 mg/L, respectively. In addition, rational adjustment of addition amount of catalyst could optimize the specific surface area of the bio-char to enhance the physical adsorption of HMs via affecting the process of bio-gas generation.

Keywords: Supercritical water gasification; Sludge; Hydrogen-rich bio-gas; Heavy metals; Immobilization efficiency (search for similar items in EconPapers)
Date: 2019
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Citations: View citations in EconPapers (1)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:189:y:2019:i:c:s0360544219319917

DOI: 10.1016/j.energy.2019.116296

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