Catalytic hydrothermal liquefaction of sewage sludge over alumina-based and attapulgite-based heterogeneous catalysts. (1st September 2022)

• Record Type: Journal Article
• Authors: Wang, Gang; Zhang, Jiaqi; Yu, Jie; Zhu, Zhe; Guo, Xiangyu; Chen, Guanyi; Pedersen, Thomas; Rosendahl, Lasse; Yu, Xiaofeng; Wang, Huan
• Is Part Of: Fuel. Volume 323(2022)
• Publication Date: 2022-09-01
• Subjects: Sewage sludge -- Hydrothermal liquefaction -- Co-Mo/ATP -- Bio-oil -- Mechanism; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.124329
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Metal catalysts (Co, Mo) supported on γ-Al2 O3 or attapulgite (ATP) were prepared. Strong promoter effects of catalysts on liquefaction of sludge were observed. The maximum bio-oil yield (31.36%) was obtained with 10% Co-Mo/ATP catalyst. Selectively higher amount of hydrocarbons (16.64%) was achieved with Co-Mo/ATP. The probable mechanism of catalytic liquefaction of sludge was proposed. Abstract: In this study, Co/γ-Al2 O3, Co-Mo/γ-Al2 O3, Co/attapulgite (ATP) and Co-Mo/ATP catalysts were prepared and applied for hydrothermal liquefaction (HTL) of sewage sludge (SS) to produce bio-oil. The properties of the catalysts were characterized by various techniques (N2 physisorption, ICP, XRD and XPS). The mesoporous nature of synthesized catalysts was conformed. Beside, Co 2+ and Mo 6+ particles were responsible as the major active species for catalytic HTL reactions. The effect of carrier and metal type, loading of catalyst on product yields and composition of bio-oil was studied. The highest bio-oil yield of 31.36 wt% was achieved in the presence of 10 wt% catalyst loading. The main components of bio-oil were phenols, N-containing compounds and hydrocarbons, and the increased selectivity to hydrocarbons with Co-Mo/ATP was observed. Meanwhile, TGA results showed that Co-Mo/ATP increased the low boiling point fraction (<410 °C) of bio-oil to 81.19 wt%. Additionally, catalytic HTL of SS resulted in higher carbon recovery, increasing from 55.61 to 92.24 wt%. Finally, the potential reaction mechanism of the catalysts on HTL of SS was proposed. Overall, this study provides valuable information for bio-oil production from sewage plant and further HTL implementation with ATP based catalyst, improving energy efficiency and alleviating the energy shortage.