Enhanced self-sintering mechanical strength of carbon blocks via removal of light molecular-weight compound in green petroleum coke

•An obviously enhanced mechanical strength was achieved in carbon blocks after removing the light molecular-weight compound in GPC.•Different fractions in GPC have significant effects on the self-sintering properties and microstructure of carbon blocks.•Dibutyl phthalate can promote the self-sintering of carbon blocks.•The pore formation caused by volatilization in carbon block is closely related to alkyl side chain of light molecular-weight compound.