Co-carbonization of ethylene tar and fluid catalytic cracking decant oil: Development of high-quality needle coke feedstock. (15th August 2022)

• Record Type: Journal Article
• Authors: Yu, Yangyang; Wang, Feng; Wiafe Biney, Bernard; Li, Keqi; Jiao, Shouhui; Chen, Kun; Liu, He; Guo, Aijun
• Is Part Of: Fuel. Volume 322(2022)
• Publication Date: 2022-08-15
• Subjects: Ethylene tar -- Fluid catalytic cracking decant oil -- Co-carbonization -- Synergistic effect -- Needle coke; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.124170
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights : Needle coke was prepared by co-carbonization of ETR and DO. Incompatibility and compatibility in the co-carbonization of blended feedstocks were revealed and analyzed. Synergistic effects of co-carbonization feedstocks were explored in terms of feedstocks composition and carbonization behavior. New blend feedstocks for high-quality needle coke with higher production than that from DO carbonization alone were developed from low cost heavy oils. Abstract: In this study, ethylene tar (ET) and refined ethylene tar (ETR) were co-carbonized with fluid catalytic cracking decant oil (DO) to prepare needle coke. The compositions and functional group changes of the blended feedstocks were revealed by Fourier transform infrared spectroscopy and 1 H nuclear magnetic resonance. Besides, the carbonization behavior of feedstocks was determined in terms of coke optical observation, carbonized gas composition, and escape rates. The morphology and performance of needle coke were evaluated by scanning electron microscopy and coefficient of thermal expansion. The results showed that the blending of DO to the feedstocks increases the H/C ratio and the content of alkyl and naphthenic structures, which improves the growth and development of the mesophase. However, the coke derived from co-carbonization of ET and DO exhibits a clear separation interface between different optical textures. Further investigation revealed that a large amount of asphaltenes in ET polymerized rapidly into mosaic texture, which hardens prematurely and cannot coalesce with the domain texture subsequently generated by DO. The compatibility of blending ETR and DO for co-carbonization improves significantly after ET is refined to remove asphaltenes. In addition, sufficient gas flow derived from DO promotes the optical microstructure of the resultant cokes by a transition from domain texture into acicular flow type. The synergistic effects between ETR and DO result in the actual CTE and yield of needle coke being lower than the theoretical ones. The CTE of NC-ETRDO50 is lowered to 1.62 × 10 -6 /°C, being almost the same as that of NC-DO, and the production growth of NC-ETRDO50 is even higher by 7.32% compared with that of NC-DO. Therefore, high-quality needle coke with high production was prepared from low-cost heavy oils.