Effect of quinoline extraction temperature on mechanical properties of self-sintering carbon blocks prepared from green petroleum coke

• The low molecular weight compounds that cause pores and microcracks defects are effectively removed by quinoline. • The flexural strength of carbon block obtained from quinoline-modified GPC at 90 ℃ is 1.71 times that of GPC counterparts. • The effect of quinoline treatment temperature on the properties and structure of carbon blocks is systematically studied. Binderless self-sintering technology using green petroleum coke (GPC) as raw material is a convenient, efficient and cost-effective approach for preparing carbon graphite materials. However, it becomes difficult to get high-performance and high-yield carbon blocks as GPC contains a large number of small molecule compounds, which will volatilize from green body during the self-sintering process, resulting in pores and microcracks defects. Herein, we propose quinoline extraction at different temperatures to remove low molecular weight compounds , i.e., quinoline soluble fraction, from GPC. The quinoline-modified GPC demonstrates enhanced thermal stability and molecular uniformity, facilitating better carbonization, even though the quinoline soluble fractions at different temperatures mainly exhibit differences in solubility. The obtained carbon blocks C-GPQ-90 demonstrates highest flexural strength (1.71 times) and compressive strength (1.73 times) than pristine GPC counterparts due to the lower porosity, the more compact microstructure, and the smaller graphite crystallite. The current approach offers an important platform to improve the mechanical properties and microstructure of the GPC products.