Study on the co-carbonization behavior of high-temperature coal tar pitch and raffinate oil of low-temperature coal tar

•Raffinate oil provided abundant alkyl radicals and for thermal polycondensation.•High aromatic feedstock with less alkyl side chains tended to form mosaic texture.•The addition of saturated components facilitated to generate planar aromatic sheets. In needle coke industry, the raffinate oil from raw material refining could be used for co-carbonization to improve the structural evolution of aromatic feedstock with high aromaticity and low alkyl side chain content. High-temperature coal tar pitch (HCTP) and raffinate oil obtained from low-temperature coal tar (LCT) were used to prepare needle coke by liquid phase carbonization, and the characteristics of carbonization behavior as well as the structural evolution of blended materials were also investigated. The raffinate oil possessed abundant saturated compositions and the aromatic component distribution mainly concentrated in 1–3 cyclic aromatic hydrocarbons which resulted in a low yield of derived products and the carbonaceous sheets with poor planarity. Raffinate oil provided sufficient small molecular volatiles of alkyl radicals and generated abundant active sites for the polycondensation of HCTP with high aromaticity and low alkyl side chain content during co-carbonization. The addition of raffinate oil in HCTP facilitated the elimination of steric hindrance and healed the structural defects within the planar aromatic lamellae. This paper improved the utilization of raw material refining treatment and optimized the industrial structure of the needle coke preparation process.