Effect of CS2 extraction on the physical properties and gasification activity of liquid-phase carbonization cokes

Two kinds of liquid-phase carbonization cokes (LPCCs) were prepared using vacuum residue (VR) and coal tar pitch (CTP) at 350–500 °C, at which the carbonaceous mesophase appears typically. And the effect of CS2 extraction on the physical properties (carbon crystalline structures, surface morphologies, surface areas and pore structures) and gasification activity of LPCCs were mainly investigated. The increasing carbonization temperature (CT) was favorable for LPCCs to form more ordered carbon crystallite structures, but their graphitization was far from natural graphite. The surface or inner pores of unextracted LPCCs conglutinated a large quantity of CS2-soluble fractions, which severely blocked the pore structure of LPCCs. Although the carbon crystalline structures of LPCCs after extraction were significantly unchanged, the BET surface areas and total pore volumes of extracted LPCCs increased significantly, which resulted in a greatly increasing gasification activity of LPCCs. And a higher extraction yield led to a higher increasing extent of gasification activity of LPCCs after extraction, regardless of precursors (VR and CTP). The soluble fractions conglutinated on the surface or inner pores of LPCCs were the most important factor of affecting on the gasification activity of LPCCs.

► A large quantity of CS2-soluble fractions conglutinated on the surface or inner pores of LPCCs. ► The carbon crystalline structures of LPCCs were almost unchanged after CS2 extraction. ► While the surface areas and pore volumes of LPCCs increased significantly. ► Consequently, the gasification activity of LPCCs enhanced greatly after extraction. ► The soluble fractions have significant effects on the gasification activity of LPCCs.