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Catalytic liquefaction of municipal sewage sludge over transition metal catalysts in ethanol-water co-solvent

Wang, Wenjia, Yu, Qi, Meng, Han, Han, Wei, Li, Jie, Zhang, Jinglai
Bioresource technology 2018 v.249 pp. 361-367
catalysts, copper sulfate, esters, gas chromatography-mass spectrometry, liquefaction, nitrogen content, sewage sludge, sulfur, temperature, thermogravimetry
Catalytic liquefaction of (Municipal sewage sludge) MSS over transition metal catalysts in ethanol-water co-solvent (EWCS) was investigated. The effect of operating parameters like temperature, holding time, and ethanol-water ratio was discussed. CuSO₄ was selected as the most efficient catalyst. The highest biocrude yield (47.45%) and liquefaction conversion (97.74%) was both obtained at the same conditions following: a reaction temperature of 270°C, a holding time of 30min, an ethanol-water ratio of 1:1, and with CuSO₄ as the catalyst. Optimized operating conditions reduced Sulfur and Nitrogen content in biocrude by 55.0% and 14.6%, respectively. The obtained biocrude samples were analyzed and characterized by thermogravimetric analysis (TGA) and gas chromatography-mass spectroscopy (GC-MS), which suggested that adding CuSO₄ increased the light-oil like content in biocrude and more than 60% of compounds in biocrude were esters. This process demonstrates the effectiveness of catalytic liquefaction of MSS in EWCS over CuSO₄ catalyst.