Cracking Characteristics of Simulated Dust-Containing Coal Pyrolysis Volatiles over Regenerated Nickel-Based Catalysts

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• 作者：Peng Liang ; Yaqing Zhang ; Aifang Wei ; Xiaohang Wang ; Tao Liu
• 刊名：Energy & Fuels
• 出版年：2015
• 出版时间：January 15, 2015
• 年：2015
• 卷：29
• 期：1
• 页码：70-77
• 全文大小：552K
• ISSN：1520-5029

文摘

Two catalysts, 2%NiO/1%CeO₂鈥揂l₂O₃ and 2%NiO/1%CeO₂/2%ZrO₂鈥揂l₂O₃, were employed in the conversion of tar in coal pyrolysis volatiles to investigate the interrelationship between dust collection and tar cracking as well as the effect of Ce/Zr doping on catalyst performance. In a fixed-bed catalytic reactor, a tar model mixture (57 wt % toluene, 14 wt % methylnaphthalene, 14 wt % cyclohexane, and 15 wt % dodecane) and simulated dusts (various metal oxides) were introduced to mimic real coal pyrolysis volatiles. The catalytic cracking activity of the latter catalyst increased with increasing temperature, space velocity, and water/model tar ratio, whereas the former catalyst exhibited the opposite trends, except with respect to temperature. Because of the formation of a Ce鈥揨rO₂ solid solution, the latter catalyst showed higher stability. During cycling tests, the deactivation of 2%NiO/1%CeO₂鈥揂l₂O₃ was observed in the seventh reaction-regeneration cycle. Nickel aggregation, observed on the surface of the catalyst by XRD analysis, may account for the deactivation. Dust deposition on the catalyst surface had a significant influence on tar modification, and the interaction mechanism between dust deposition and coke formation was clarified. The electron probe microanalysis results showed that SiO₂ tends to promote carbon deposition, whereas MgO and Fe₂O₃ components have a negative influence on carbon deposition. This study can serve as a reliable reference for the practical development and modification of purification processes for coal pyrolysis volatiles.